jj -• - • , '/W/// / 9 e^ O THE GALLERY OF NATURE Ba,Tios , Peru. t* & 9*9 iA.SUmi w i ' TOlilli TR-ROilCW CIBEATI10W THOMA "WI1L3L.IAM & E.OJBKE.T (DMAMBEM.S LOSDOT & THE GALLERY OF NATURE f uiorial &nfo gwrijiib* TOUR THROUGH CREATION ILLUSTRATIVE OF THE WONDERS OF ASTRONOMY.. PHYSICAL GEOGRAPHY, AND GEOLOGY BY THE REV. THOMAS MttNER, M.A., F.R.G.S. 4. I8*a. AUTHOR OF 'ASTRONOMY AXD SCRIPTURE,' ETC. ETC. CAREFULLY REVISED AND CORRECTED BY THE AUTHOR LONDON W. AND R. CHAMBERS, 47 PATERNOSTER ROW AND HIGH STREET EDINBURGH MDCOCLX £{ Edinburgh : Printed by Vf. and R. Chambers. Bancroft Ub&& TO THE FIRST EDITION. HE present Volume is intended to furnish a very general view of the leading appearances of Physical Nature — the economy of the heavens and the earth — with incidental notices of the progress of discovery, and pictorial representations of remarkable phenomena and interesting localities. Kegarding it as one of the happy tendencies of the age, to be more in favour of intellectual occupations than of the vulgar animal recreations that were formerly courted, the writer has endeavoured to supply a digest of the knowledge obtained respecting the " wondrous whole," of which we form a part, which the enterprise of the proprietors of the work has profusely illustrated. In submitting the accomplishment of this design to the judgment of the public, the writer may be allowed to observe, that he was called to the task at a very short notice ; that disadvantageous circumstances, which could neither be foreseen nor avoided, have much interfered with its execution ; but that he has honestly endeavoured, amid professional engagements, and oft-recurring physical debility, to carry out the design of the projectors. THE AUTHOR. The extensive sale experienced by Milner's GALLERY OF NATURE since its first publication, a few years ago, is the best proof of the happy adaptation of the book to its object ; which was to convey to the popular mind — to the young in particular — a general idea of the external Wonders of the Heavens and the Earth. Written in an easy and agreeable style, and profusely illustrated, it may fairly be said to have gained a position above all the similar works of its day. To sustain its place as a favourite Gift-book and useful member of the Village Library, it seems only necessary that it should be kept, in all particulars, in harmony with the present state of Science. The Work has now accordingly been carefully and thoroughly revised by the Author, with the advantage of all recent additions and corrections supplied by modern investigators, and with the further benefit of a considerable number of new illustrations. W. & R C. TABLE OF CONTENTS. HISTORY OF ASTRONOMICAL DISCOYERY. CHAP. I. PAGE ERA OF THE GREEK AND ALEXANDRIAN SCHOOLS, 1 CHAP. II. ERA OP COPERNICUS, TYCHO BRAHE, EEPPLER, AND GALILEO, .... 17 CHAP. III. ERA OF NEWTON, HALLEY, AND HERSCHEL, . 33 SCENERY OP THE HEAVENS. . 49 . 63 . 76 CHAP. I. THE SUN AND SOLAR PHENOMENA, CHAP. H. MERCURY, VENUS, THE EARTH, . CHAP. III. THE MOON AND LUNAR PHENOMENA, CHAP. IV. MARS, PLANETOIDS, JUPITER, SATURN, URANUS, NEPTUNB, . . . . .89 CHAP. V. COMETS, . .108 CHAP. VI. AEROLITES, . CHAP. VII. A GLANCE AT THE STARS, . . 130 143 CHAP. VIII. NUMBER, DISTANCE, AND MAGNITUDE OF STARS, 158 CHAP. IX. NEW, VARIABLE, AND COMPOUND STARS, CHAP. X. STAB-SYSTEMS — NEBUL.fi, PAGE 166 180 APPENDIX. ELEMENTS OS1 THE SOLAR SYSTEM, . . 189 OBSERVATORIES, . . . 192 PHYSICAL GEOGRAPHY. CHAP. I. GREAT NATURAL DIVISIONS OF THE EARTH, . 193 CHAP. II. HIGH LANDS OF THE EARTH, . . 200 CHAP. III. VALLEYS AND GREAT LEVELS OF THE EARTH, 217 CHAP. IV. CAVERNS AND SUBTERRANEAN PASSAGES, CHAP. V. SPRINGS, LAKES, THE OCEAN, 238 259 CHAP. VI. CHAP. VII. CHAP. VIII. 278 308 325 VI CONTENTS. CHAP. IX. TIDES AND OCEANIC HIGHWAYS, . CHAP. X. CHANGES IN OCEANIC REGIONS, CHAP. XI. ALTERATIONS OP COAST-LINE, CHAP. XII. INTERIOR LAND CHANGES, . CHAP. XIII. THB ATMOSPHERE AND ITS CURRENTS, CHAP. XIV. AQUEOUS ATMOSPHERIC PHENOMENA, CHAP. XV. PHTSICAL CLIMATE, . . . CHAP. XVI. OPTICAL PHENOMENA, CHAP. XVII. GEOGRAPHICAL DISTRIBUTION OP PLANTS, CHAP. XVIII. DISTRIBUTION OP ANIMALS, CHAP. XIX. DISTRIBUTION OP THE HUMAN RACE, GEOLOGY. INTRODUCTORY CHAPTER, CHAP. I. THB STRUCTURE AND CLASSIFICATION OF ROCKS, 349 370 386 407 435 461 484 51C 546 571 595 fill 622 CHAP. II. PLUTONIC OR IGNEOUS HOCKS, PAOK 613 CHAP. III. GNEISS, MICA SCHIST, AND CLAY SLATE SYSTEMS, 657 CHAP. IV. THE SILURIAN SYSTEM, 6C7 CHAP. V. THE OLD RED SANDSTONE SYSTEM, . . 6S1 CHAP. VI. THE CARBONIFEROUS SYSTEM, . . 690 CHAP. VII. THE PERMIAN AND TRIASSIC SYSTEMS — LOWER AND UPPER NEW RED SANDSTONE, . 707 CHAP. VIII. THE OOLITIC SYSTEM, . . . 717 CHAP. IX. THE CRETACEOUS SYSTEM, . . .731 CHAP. X. THE TERTIARY SYSTEM, . . . 737 CHAP. XL DRIFT AND ERRATIC BLOCKS, . . 751 CHAP. XII. ALLUVIUM — RECENT FORMATIONS, . 7C6 CHAP. XIII. GENERAL INDICATIONS, 7S4 Vs — " ENGRAVINGS ON STEEL. ERRATUM. ON page 490 reference is made to a Meteorological Map. This map existed in former editions, but was for various reasons omitted in the present one. The reference has, by an awkward overlook, been allowed to stand. ENGRAVINGS ON WOOD. Page BirsNimrood, ..... 1 Portrait of Thalcs, ..... 6 Portrait of Pythagoras, .... 8 Aristarchus's Plan of Earth's distance from the Sun, 9 Eratosthenes's Plan of Earth's magnitude, . . 9 Portrait of Ptolemy, . . . . 11 System of Ptolemy, . . . . .12 Mars and Jupiter's Circuits, ... 12 System of Hipparchus, . . . . .13 Ptolemy's Theory of Epicycles, ... 13 Obelisk at Heliopolis, ..... 15 Tail-piece, ...... 16 Portraits of Copernicus, Keppler, and Galileo, . 17 Initial Letter, 17 Motions of the Planet?, . . . . .21 Portrait of Tycho BraM, .... 22 System of Tycho, Earth's motion on its axis, , Tycho Brahe's Observatory, Refraction of the Atmosphere, Uraniberg, or Castle of the Heavens, . Unequal velocity of the Planets, Portraits of Halley, Newton, and Herschel, Initial Letter, . Velocity of Light, Greenwich Observatory, Newton's Birthplace, Newton's Theory of Attractions, Newton's Theory of Centrifugal Force, Room in which Newton was born, . Bailey's Tomb, .... Aberration of the Stars, . . P-ge . 22 23 . 24 25 . 23 27 . 33 33 . 35 3<5 . 33 39 . 39 40 . 41 42,43 VI CHAP. IX. TIDES AND OCEANIC HIGHWAYS, . CHAP. X. CHANGK3 IS OCBAKIC REGIONS, CHAP. XI. ALTERATIONS OF COAST-LINK, CHAP. XII. INTERIOR LAND CHANGES, . CHAP. XIII. THK ATMOSPHERE AND ITS CURRENTS, CHAP. XIV. AQUEOUS ATMOSPHERIC PHENOMENA, CHAP. XV. PHYSICAL CLIMATE, CONTENTS. 349 370 886 407 435 461 484 CHAP. II. PLUTONIC OR IGNEOUS SOCKS, PAO* 613 CHAP. III. GNEISS, 1IICA SCHIST, AND CLAY SLATE SYSTEMS, G57 CHAP. IV. THE SILURIAN SYSTEM, . CHAP. V. THE OLD RED SANDSTONE SYSTEM, CHAP. VI. THE CARBONIFEROUS SYSTEM, 6C7 CS1 G90 CHAP. VII. THE PERMIAN AND TRIASSIC SYSTEMS — LOWER AND UPPER NEW RED SANDSTONE, . 707 A/- ENGEAVINGS ON STEEL. THE BANGS PASS, I'ERU, ...... UPPER GLACIER OF THE GRINDELWALD, ..... MAPS OP THE SIDEREAL HEAVENS — JANUARY TO APRIL, ...... APRIL TO JULY, ....... AUGUST TO OCTOBER, ...... NOVEMBER TO JANUARY, ..... ANNUAL REVOLUTION OP THE EARTH ROUND THE SUN, PHASES AND MOVEMENTS OP THE MOON ROUND THE EARTH, . MAP OP THE MOON, REDUCED FROM THE LARGE MAP OP MM. BAER AND MADLER, CRATER OF KILAUEA, ....... LA VINDA PASS, PERU, ....... PETRIFIED CASCADE NEAR PAJIBOUKKALI3E (THE ANCIENT JIIERAPOLIS), MAP OP THE ORINOCO, ....... ESTROZA PASS, MADEIRA, CHARACTER OF CLOUDS, ...... CEDARS OF SOLOMON, MOUNT LEBANON, ..... PAGE Frontispiece. Vignette. xii ib. ib. ib. 72 80 8B . 210 230 . 277 299 . 415 464 559 ENGRAVINGS ON WOOD. Page Birs Nimrood, ..... 1 Portrait of Thalcs, ..... 6 Portrait of Pythagoras, .... 8 Aristarchus's Plan of Earth's distance from the Sun, 9 Eratosthenes' s Plan of Earth's magnitude, . . 9 Portrait of Ptolemy, .... 11 System of Ptolemy, . . . . .12 Mars and Jupiter's Circuits, ... 12 System of Hipparchus, . . . . .13 Ptolemy's Theory of Epicycles, ... 13 Obelisk at Heliopolis, . . . . .15 Tail-piece, ...... 16 Portraits of Copernicus, Keppler, and Galileo, . 17 Initial Letter, ..... 17 Motions of the Planets, . . . . .21 Portrait of Tycho Brah£, .... 22 System of Tycho, Earth's motion on its axis, , Tycho Brahe's Observatory, Eefraction of the Atmosphere, Uraniberg, or Castle of the Heavens, . Unequal velocity of the Planets, Portraits of Halley, Newton, and Herschel, Initial Letter, . Velocity of Light, Greenwich Observatory, Newton's Birthplace, Newton's Theory of Attractions, Newton's Theory of Centrifugal Force, Room in which Newton was born, . Bailey's Tomb, .... Aberration of the Stars. Vlll ILLUSTRATIONS. F«g« Tail-piece— Bailey's Cornet, .... 48 Illustrated Title— Astronomy, ... 49 Sun at Midnight at the North Cape, ... 51 Vertical and Horizontal Kays of the Sun, Spots in the Sun, .... Eclipses of the Sun, . • 68,59 Annular Eclipse, . . . • .69 Corona encircling the Moon in a Solar Eclipse, . 62 Zodiacal Light, 62 Orbits of the Planets, .... 64 Transit of Mercury, ..... 65 Orbit of Venus, ..... 67 Physical constitution of Venus, . . .69 Vessels at Sea, shewing the Rotundity of the Earth, 70 Sycne, near Alexandria, .... 71 Translation of the Earth in space, . 73 Orbit of the Earth, ..... 73 Precession of the Equinoxes, . . . .74 Atmosphere of the Earth, .... 75 Tail-piece— Sunset, ..... 75 Initial Letter — Moonlight, .... 76 Phases of the Moon, ..... 77 Eclipse of the Moon, .... 79 Uneven Surface of the Moon, .... 83 Tail-piece— Moonlight at Sea, ... 88 Initial Letter, ...... 89 Aspect of Mars, ..... 91 Aspect of the Earth viewed from Mars, . . 91 Aspect of Jupiter, ..... 95 Jupiter and his Satellites, . . . .90 The Thames by Moonlight, ... 87 Saturn and his Rings, ..... 98 Orbit of Saturn, ..... 100 Phases of Saturn, ..... 100 Rings of Saturn, ..... 101 Comparative size of the Sun as seen from the Planets, 105 Relative bulk of the Planets, . . . .106 Initial Letter, ..... 108 Path of the Comet of 1C80, . . . .110 Tail of a Comet, Ill Comet of 1456, as seen at Constantinople, . . 115 Comet of 1835, ..... 116 Fancied Forms of Comets, copied from a Celestial Atlas of 1680, 116 Comet of 1744, ..... 118 Schroeter and Bessel's Drawings of the Comet of 1807, 119 Comet of 1811, as seen at Winchester, . . 120 Comet of 1811, 121 Telescopic view of Encke's Comet, . . . 122 Orbit of the Comet of 1832, ... 123 Comet of 1843, as seen on the Essequibo, . . 126 Various appearances of 118116/8 Comet in 1833, . 127 Initial Letter, 130 Meteoric Shower in Greenland, . . . 138 Meteoric Shower at the Falls of Niagara, . . 139 Meteoric Shower on Lake Niagara, . . 140 Radiation of Meteors, . . . . .141 Orbit of Meteoric Shower of Nov. 13, 1833, . 142 Initial Letter, 143 Mouth of the Dardanelles, .... 145 Banks of the Euphrates, .... 145 Constellations — Aries, ...... 149 Tanrus, Gemini, Cancer, . . . .150 Leo, Virgo, Libra, Scorpio, Sagittarius, . 151 Capricornus, Aquarius, Pisces, . . . 152 The Pointers in Ursa Major, ... 153 Ursa Major moving round the Pole, . . 153 Orion, 154 Southern Cross, 155 P»ge 158 . 160 161 . 162 166 . 167 1C9 . 170 173, 174 . 174 175 . 179 180 . 181 182 . 184 184 . 187 187 . 188 192 . 193 194 . 195 193 . 190 200 . 201 202 . 211 213 . 215 215 . 216 217 . 218 220 . 222 224 . 225 226 . 227 223 . 231 237 238 . 239 241 Peveril of the Peak's Castle, with the Mouth of the Cave, 243 The Cupola Cavern, Organ, Blue John Cavern, Kirkdale Cave, Kent's Cave, near Torquay, . . . .253 Gailenreuth, ..... Section of Gailenreuth Cave, . Grotto del Cane, Caverns of Dudley Castle, . . • 257 Entrance to Odin's Mine, . Initial Letter — Fountain of Arethusa, . . 259 Castalian Spring on Mount Parnassus, . . 260 St Winifred's Well, . . . 264 Intermittent Spring, Artesian Well, Pool of Siloam, The Great Geyser, Iceland, Ebullient Spring, ..... Dripping Well, Knaresborongh, Initial Letter— Falls of Tivoli, The Susquehanna, ..... 2S1 Initial Letter, Herschel's Telescope, .... Parallax, ...... Earth's distance from the Stars, Initial Letter, ..... New Star observed in 1572, Supposed Orbit of a temporary Star, Variable Star observed in 1596, Binary Stars, ..... Theory of Double Stars, Positions of Double Stars in different years, Tail-piece— The Earth, .... Initial Letter, ..... Architecture of the Stellar Universe, . Nebula in Hercules, .... Nebula in Andromeda, . . Planetary and Double Nebulae, Crab Nebula, . Dumb-bell Nebula, .... Spiral Nebulae, ..... Tail-piece— Nebulae, Illustrated Title— Physical Geography, Port of Sidon from the Sea, Chart of the World, .... Leuctra and Cape Matapan, . Mouth of the Bosphorus, Initial Letter, . Mount Egmont in New Zealand, Peter Botte Mountain, .... Cotopaxi, Mount Etna, from Syracuse, Bolivian Plateau, .... Mexican Plateau, . Plateau of Central Asia, Initial Letter, . Defile of the Darial, . Glacier of the Rhone, .... Dovedale, Great Plain of the Caucasus, Mount Kasibeck, and Steppes of the Caucasus, Lake of Mandia, .... Sand-storm in the Desert, Ruins of Palmyra, from the Desert, Llanos of Badajoz, The Pyrenees from the Great Plain of LangueJoc, Initial Letter— Kirkdale Cave, Jorullo, Mexico, Cave of Fingal, ILLUSTRATIONS. IX Page The Rhine at Oberweise), .... 282 Kaaterskill Falls, 284 Falls of Trolhetta, 286 Falls of Terni, .... .286 Natural Bridge, Virginia, .... 291 Valley of the Concon, Chili, . . . .293 The Nile at the Pyramids, .... 296 Source of the Angitas, . . . . .300 Natural Bridge of Ain el Leban, ... 301 Delta of the Ganges, 302 Initial Letter— Derwentwater, ... 308 Loch Katrine, 309 The Kandal Steig, Switzerland, ... 310 Cascade in Mount Taurus, .... 313 The Dead Sea, ..... 314 Lake Saratoga, 321 Lake of Joannina, ..... 323 Caderldris, ...... 324 Initial Letter — Source of the Jordan, . . 325 St Helena, ...... 326 Fiord of Norway, ..... 332 Gale in the Pacific, ..... 335 Temperature of the Ocean, .... 335 Icefields, 337 Icebergs, ...... 333 The .Egean Sea from -Egina, . . . .346 The Mouth of the Bosphorus, ... 347 Cape Horn, ...... 348 Initial Letter, ..... 349 Tidal influence of the Moon, . . . .353 Tidal influence of the Sun, .... 354 Lancaster Sands, ..... 355 Diagram of Atlantic Tides, . . . 355 Tide-waves around Great Britain, . . . 366 Port of JEgina, ..... 357 Solway Sands, ...... 359 Cronburg Castle, and Entrance to the Sound, . 363 Sinope, on the Black Sea, .... 3C5 Straits of Gibraltar, .... 366 Initial Letter— Bass Rock, .... 370 The Valley of Chamouni after a Flood, . . 372 Barren Island, ...... 375 Hotham Island, ..... 377 Island of St Eustatia, West Indies, . . .379 Blocks of Coral, ..... 380 Aurora Island, ...... 3S1 Dean's Island, ..... 381 Banks of the Euphrates, .... 335 Initial Letter— Whitby Abbey, ... 886 Undercliff, Isle of Wight, . . . .391 Hob-Hole, Whitby, .... 393 The Needles, Isle of Wight, . . . .394 Bay of Alexandria, ..... 397 Coast of Asia Minor, from the Isle of Samoa, . 398 Gulf of Trieste, ..... 399 Map of Coast of Baia, ..... 403 Coast of Pozzuoli, . . . . 404 Plains of Kosova, ..... 40G Initial Letter, ..... 407 The Righi Pass, . . . . .409 Valley of the Adige, .... 413 Rhymer's Hill, ...... 417 White Mountain, in the Alleghanies, . . 419 Plains of Thebes, . . . . .422 Extinct Volcano, Catecucaumene, . . . 430 Fissures at Polistena, ..... 432 Circular Hollows at Polistena, ... 433 Volcano of Orizaba, ..... 434 Initial Letter— Balloon, .... 435 A Calm at Sea, ..... 438 Commencement of the Monsoon, . Vesuvius from St Elmo, Hurricane in the Tropics, . Waterspout in the Mediterranean, Tail-piece — Man overboard, Initial Letter — Ignis Fatuus, . Loch Achray, . . . Durrenstein on the Danube, . Thunder-storm, Various forms of Snow Crystals, Dogs of St Bernard, Snow-storm, . . . Castle of the Seven Towers, Initial Letter, . Plains of Beloochistan, Page 443 445 451 457 460 4G1 465 466 469 475 477 478 433 484 485 Line of Perpetual Snow, .... 486 Mount Ararat, ..... 488 Gorge of the Tyrolese Alps, .... 490 Alleghany Mountains, .... 494 The Andes, ...... 498 Cape of Good Hope, .... 503 Theodomer marching his Army across the Danube, 509 Fair on the River Thames, 1716, . . .612 Boiling Mud of Iceland, .... 615 Initial Letter — Mirage, .... 616 Tower of St Mark's, Venice, . . . 621 Aurora Borealis, Loch Leven, . . . 624 Aurora Borealis, Hudson's Bay, . . . 526 Halo, ....... 631 Parhelia, ...... 531 Rainbow, Rosamond's Bower, . . . 533 Lunar Rainbow, ..... 634 Mirage of the Desert, ..... 536 Atmospheric Illusion, .... 637 Fata Morgana at Reggio, .... 538 Spectre of the Brocken, . . . • . 641 Refraction in the Polar Sea, .... 643 Ignis Fatuus, ..... 544 Initial Letter, 646 The Ortler Spitz, 647 Pine Forest . 653 Banyan Tree, 654 Palm Forests, ...... 556 Cedars of Lebanon, ..... 659 Initial Letter, ...... 571 Shell of the Sea-urchin, .... 672 Group of Fish, ...... 577 Boa Constrictor and Rattlesnake, . . . 679 Group of Birds, . . . . .681 Group of Animals, ..... 6S5 Tail-piece, ...... 694 Initial Letter, ..... 595 Esquimaux Hut, ..... 697 Classical Heads, ..... C02 Groups of Physiognomical Portraits, . . 603, 604, C06 South-Sea Islanders, .... 610 Illustrated Title— Geology : Restoration of Ante diluvian Animals, ..... 611 Limestone Rocks in the Gulf of Corinth, . 612 Land-slip, ...... 613 Castalian Spring, ..... 614 Limestone Mountains on the Coast of Arcadia, . 616 Granite Rocks of Meteora in Albania, . . 621 Cave of Jupiter, ^gina, .... C22 Lamination of Rocks, .... 625 Unstratified Rocks, . . . 625 626 Basalt Columns, Basalt Rocks on the Volant, Titan's Piazza, Stratified Rocks, 626 . 626 626 627—630 ILLUSTRATIONS. Page Crich-hilL Derbyshire, . .628 Section of the Jura Mountains, . . .630 Association of Stratified and Unstratified Rocks, 631—633 Interior of a Silver Mine, . .634 Classification of Rocks, ... 638 Catenipora cscharoides, . • 640 Sphsenopteris Hseninghausi, . 640 Encriuites moniliformis, .... 640 Ammonite Catena, . . . 640 Turrilites costatus, and Mocesamus concentricus, . 641 Skeleton of the Anoplotherium, . . . 641 Skeleton of the Megatherium, .... €41 Lurly on the Rhine, .... 613 Granite, ...... 644 Ben Lomond, from the Lake, ... 646 Aiguille de Dru, 647 Disintegrated Granite, .... 648 Granite Veins, .... 649—650 Serpentine, ..... 661 Positions of Trap, ..... 652 Basalts 653—654 Grotte des Fromages, ..... 653 Porphyry, ...... 655 Needle Rocks, Isle of Wight, . . . 656 Initial Letter, ..... 657 Gneiss System, ...... 658 Mica-schist System, .... 659 Mount Taygetus, from the Plains of Sparta, . 660 Skiddaw Mountains, .... 6G3 Fossils from Snowdon, .... 665 Nereites Cambrensis, .... 666 Initial Letter— The Bone Well, Ludlow, . . 667 Hills near Brecon, ..... 667 Silurian System of Rocks, . . . .669 Vale of the Towy, ..... 671 Trilobites, ...... 671 Eye of the Trilobite, .... 672 The Stiper Stones, . . . • . .673 Terebratulse, ..... 674 Old Lincoln Quarry, near Iron Bridge, . . 675 Euomphala, ..... 675 Wenlock Limestone, ..... 676 Ludlow Corals, ..... 678 Wenlock Corals, . . . . .678 Remains of Fishes, ..... 679 Palmer's Cairns, Ludlow, .... 680 Initial Letter— Trap Dyke, BrockhilL Worcester, 681 Old Red Sandstone, near Bristol Channel, . . 632 Vegetable Remains in Old Red Sandstone, . 684 Scales of Fossil Fishes, . . .685 Tails of the Shark, Trout, and Wrasse, . . 686 Scales on head of Cephalaspis, . . . 687 Coccosteus cuspidatus, .... 687 Pterichthys, .... 688 Initial Letter— Carboniferous System, . . 690 Mountain Limestone, ..... G91 Section of the Crich-hill, .... 692 Encrinal Limestone, ..... C93 Orthoceras lateralis, and Bellerophon costatus, . C93 Teeth of the Hybodants and Megalichthys, . . <".)4 Projection of Millstone Grit, ... 695 Section of the Bristol Coal-field, . . .698 Fault in Coal-field, ..... C98 Imaginary section before disturbance, . . 699 Section after disturbance, .... 699 Seam dipping, .... 700 Turnpike Stair in Coal-mine, ... 700 Tropical Fern, . . . . . .703 Annularia brevifolia, and Sphenophylluni dentatum, 703 Sigillariae, . . . . . .704 Section of a Coal-mine near Etienne, . . 704 Fossil Trees on the Bolton and Manchester Railway, 705 Stigmaria and Lepidodendron, . . . 705 Calamites, . 706 Tree in Craigleith Quarry, .... Initial Letter— Caverns under Nottingham Castle, . Conifera and Cycarlea, . . Nottingham Castle, . . . . Labrinthodon pachygnatus, Foot-print and Rain-drops, .... Tracks of the Chirotherium, Slab of New Red Sandstone, with Foot-prints, Dipterus, ...... Initial Letter— Limestone Ridges at Leuctra, Shells of the Lias group, .... Ammonites, . . . Belemnite, ...... Cidaris coronata, and Spatangus, Restoration of Saurians and other Animals of the Lias, ...... Jaw of the Phascolotherium, .... Astarte elegans, ..... Iguana cornuta, ..... Initial Letter, . . . Trigonia, ...... Spherulites and Hippurites, Terebratula, ...... Spatangus, ...... 706 707 709 710 713 714 714 715 716 717 719 719 720 721 724 726 728 729 731 732 733 733 735 Tail-piece, ...... 736 Mount Parnassus, ..... 737 Marls with Magnesite, ..... 738 London Basin, ..... 741 Alum Bay, Isle of Wight, . . . .742 Cerithium giganteum, .... 744 Animals of the Paris Basin, .... 745 Extinct Volcanoes of Auvergne, . . . 746 Cama foliacea, Palmacites Lamanonis, Lyuinca longiscala, and Balanus crassus, . . . 748 Restoration and Lower Jaw of the Dinothcrium, . 748 Murex alveolatus, ..... 750 Initial Letter— Erratic Blocks in Massachusetts, . 751 Monument Mountain, ..... 752 Tooth of the Mastodon, .... 754 Remains of a Salamander, .... 759 Drift near Cape Cod, .... 761 Rocking-stone, Fall River, .... 7C1 Block in Cornwall, ..... 762 Broken Ledges of Slate, .... 763 Strata smoothed and striated by Drift, . . 7C4 Diluvial Formations seen from the Acropolis at Athens, 7C5 Cyclopean Remains, Mycene, .... Plains of Mantinea, in Arcadia, Corals, ....... Coast of Northern Greece, from the Gulf of Corinth, Temple of Jupiter Serapis, Section of a Terraced Valley, .... Chart and View of the Isle of Palma, Crater of Vesuvius in 1829, Volcano of Jorullo, . Descent of the Curral, Madeira, Initial Letter — American Aloe, Barren Island, Gulf of Bengal, 766 7C6 768 773 774 . 777 779, 780 . 781 782 . 783 784 . 7S8 Various Tail-pieces, Vignettes, &c. DESCRIPTION AND USE OF THE SIDEKEAL MAPS, THESE Maps have been constructed to show the sidereal hemisphere visible on the parallel of Greenwich, and being also adapted to the meridian of Greenwich, they are drawn on the plane of that horizon. To insure the greatest amount of accuracy, the stereographic projection has been made use of, because of all projections that occasions the least possible disarrangement of the relative position of the stars and of the angles they form one with another. There is a difficulty in reducing a concave surface to a plane without distortion taking place somewhere, and in the projection here adopted a little compression will be found, gradually increasing from the horizon to the centre of the map. The constellations when at or near the zenith, will be found to be somewhat smaller than when at the extremities of the projection or near the horizon. Three, four, or five stars may appear in the heavens so as to form a group, and present to the observer the appearance of a triangle, a rhomboid, trapezium, or parallelogram, which figures are more correctly preserved by this projection than by any other which might have been made use of. The difference between celestial and terrestrial maps should not be lost sight of. When a comparative observation is made between one of these maps and the heavens at any of the times given on the next page, the map should be held up in a vertical position, placing that part of the map downwards towards which the observer is directing his attention. For instance, if the stars in the south are to be examined, the person's face must be turned that way, with the south or bottom of the map downwards ; if for the north, the map must be reversed, with the north or top of the map downwards, when a complete view of the heavens in either of those directions will be obtained. If for the east and west, the sides of the map are to be similarly held, corresponding with the aspect required. The centre of each map represents the zenith, that part of the heavens which is exactly over the obser ver's head, and will answer equally well for any other place upon the same parallel of latitude, making the allowance of four minutes for each degree, east or west, sooner or later ; which shows that all persons living on the same parallel of latitude have in succession the same view of the starry concave. Another appearance would be presented if the observer were at either of the poles. Supposing there were inhabitants at the North Pole, to them one half of the firmament would never set, and the other half would never rise. The polar star would be their zenith, and appear quite stationary, with all the other stars in view revolving round it in circles. To such inhabitants the equator would be the horizon, and at whatever elevation a star was first seen in their winter, there it would remain, and appear to complete a circle at that elevation once in every twenty-four hours. If there were inhabitants at the South Pole, they would be similarly situated with regard to stars in the southern hemisphere ; they would never see the stars on the north side of the equator or northern hemi sphere, nor would those in the southern hemisphere ever set to them. To the inhabitants of the equator, the whole of the stars from pole to pole, rise and set perpendicularly to their horizon once in every twenty-four hours. As the equator has no parallel of latitude, so has its zenith no declination, because the celestial equator passes immediately over it in a line from east to west. If an observer moves towards either pole from the equator; for every degree of his progress his zenith will have just so many degrees of declination, and as many degrees can he see beyond the pole towards which he is advancing, and he will lose sight of the pole from which he is receding in the same proportion. For example, as the inhabitants of London are situated 5U° from the equator northwards, their zenith is 51^° elevated above the celestial equator. As 51 i° is the distance from the zenith to the equator, it follows that 38^° must be seen by an inhabitant of London below the equator to make up the complement of the quadrant, or 90°. Between the zenith and the pole will be found 38^°, requiring 51^° beyond the pole to complete the other quadrant of 90°, thus together completing the hemisphere of 180°. With these preliminary explanations a few words will explain the use of the maps. Each map may be supposed to represent the heavens at the hours named. The dotted circle crossing Xll DESCRIPTION AND USE OP THE SIDEREAL MAPS. the graduated meridian line at 41°, is the circle of perpetual apparition, the stars within that circle being visible at all times from the meridian of Greenwich. The maps may, by a little calculation, be made to represent the aspect of the heavens at other times than is named ; for instance, reckoning backwards, and allowing a difference of about twenty minutes for every five days or four minutes for every twenty-four hours, we find that on the 21st of January at 40 minutes past 1 o'clock in the morning, the stars will appear as they are represented in the map for March, and so on for every other month, following the same reckoning for every day in the year. TABLE SHOWING THE HOUR AND DAY WHEN THE STARS OCCUPY THE POSITION INDICATED IN THE MAP. January 21 26 February 1 6 11 16 April May 22 27 2 7 12 17 22 26 31 5 10 15 20 25 November 3 8 13 18 23 28 July August lir. 1 1 1 12 12 12 br. 2 1 1 1 12 12 12 hr. 1 1 1 12 12 12 11 hr. 1 I 12 12 12 11 Map for March. •10 •JO o 40 90 o 90 O 40 BO 0 February 21 March May June 26 3 8 13 18 hr. - 11 - 11 - 11 - 10 - 10 - 10 Map for June. 27 1 6 11 16 21 hr. - 11 - 11 vll - 10 - 10 - 10 August 30 September 4 9 14 19 24 29 Map for September. hr. - 11 - 11 - 1O - 10 - 10 - 9 - 9 Map for December. December 3 8 13 18 « 23 28 hr. - 11 - 11 - 10 - 10 - 1(1 - 9 •10 •JO o •10 90 0 90 O •10 m o -10 March April June July October January 23 28 7 12 17 €6 1 G 11 16 21 4 9 14 19 24 29 3 8 13 18 23 28 hr. 9 9 9 7 7 7 hr. 9 9 9 hr. 9 8 8 8 7 7 hr. 9 9 8 8 8 7 49 20 O 40 20 O 40 20 O 40 20 0 O 20 20 O 40 20 20 O 40 20 O 40 • - Temple of the Winds, Athens. Ubrary (Off T This Map represents the Stars as they rruiy be observ, during the qre.ah'r part of January, February, and March, at the hours Circle which crosses the graduated. Me ridian, at 41? is the Circle, of perpe.t luil apparition thi> Stars that Circle, heing vistl/ls, a all, thncs trom. the. Meri dian of Irreenwi ch. In niiruj the Map, place it over the Head the top point ing tow arils tJie North, and- if the Night he suffi ciently (Lark and brirjht^tlie Stars may be trotted occupying the position in/If ca.- ted in the Map at any of the times JEty reckoning nil/ 20, inimitf.s for every £>, days, the Map may lie ~nt.aJle to apply to any other dny or hour during which the Stars are. visible. 03 BIPAIEfi VIEW THIS MONTH THKIR MAGNITUDEvS. . Library ML- This .Vv///.c tiit- >'/nl. Mu\, iin,d, th,- d, an of Ijrevnw/ ch 1 vA/r April - -' OIL , 3SA1T a In using the May, pla.cc it over the If caul, the. top pointing towards the North, and if the. Night /><• ruffieLm&y dark and Tjri,qltt, the Stars ma\ he traced, occupying the position indi,caJzd in the Map at any of. the tim&s named. v^ By reckoning hack aHo\\ >•> \ mqW, minutes for e\'ery X V ' ^V ^ 5, days, the. Map may be -made to apply to any other day or hour during which the Stars are visible. IN VJKW THIS MONTH AND THEIR MAONITI'DES o MAP ©F THE HEATOMS EM This Map, represent* t)u- >'/,//-.»• !w.- y*. u IP ** u 0 13*= 10 40 Iff*- IQ SD is?. iff . 0 20* j> 4O Jtm». llff .9 2t> g*' 9 0 13$ 9 40 off' a a» *r* <» M* .7 40 KO HBMBXR, In, iLsing th& Map place it over bhii Head., the top point i rig towards the North, and it' the Night be suffici 'titly dark and bright, the. Stars may be. traj;ed occupying the. position- indLca, ted in. t}ui Nap at any of the times e.d. By re.d&mijiy bad*, allow - Lg 20, minutes for every 5, days, the. Map may be made to apply to any other day or hour during M.-fof the Stars are vi.sible. BlRS KlMROOD. HISTORY OF ASTRONOMICAL DISCOVERY. CHAPTER I. ERA OF THE GREEK AND ALEXANDRIAN SCHOOLS. ASTRONOMY, now the most perfect of all the sciences, is also the most sublime and an cient. It separates man in thought from the spot upon which his foot is planted ; makes him acquainted with forms and spaces, in comparison with which terrestrial magnitude and distance shrink into insignificance ; and unfolds the constitution of the universe, as a scheme involving the intimate connection of the mighty and remote masses that are open to observation, — their incessant activity, unfailing order, and mutual dependence. The idea of extension — a feature of the sublime — is created by the scenes with which we are in immediate contiguity, and enlarged by the knowledge we possess of the superficies of the globe ; but it is wonderfully expanded by the science which deals with the objects that are exterior to its surface. 33y measuring the distances and volume, and weighing the masses, of the planets — by calculating the orbits of the comets, which accomplish their aphelia in the regions of invisibility, and only discover themselves to us during a scanty portion of their course — by contemplating the stellar firmament, which, in the case of its nearest members, has required the highest modern intelli gence, aided by the finest instruments, to detect even the slightest amount of parallax — by such investigations as these, we gather some faint conception, improving to our nature, yet humbling to our faculties, of the immensity in which the Creator centres, with whom the vast scheme originated, and to whom alone it is reserved to estimate 2 HISTORY OF ASTROXOillCAX DISCOVERY. its length and breadth, its depth and height. Man has learnt to distrust and disbelieve the evidence of the most perfect of his senses. He has been taught that the apparently quiescent earth is in perpetual movement ; that the real motions of the celestial bodies are, in most cases, in direct antagonism to those which he daily perceives ; and that his own world, instead of being the " greatest in the kingdom of heaven," having subordinates under it in the sun, moon, and stars — the long and fondly cherished dream of antiquity — is, in reality, one of the smallest provinces in the great empire of Nature. Astronomical inquiry goes back to a remote era, and had its origin in the East. The splendour of the celestial phenomena ; the fact of periodical changes and of accompanying powerful effects being produced upon the surface of the earth — such as alterations in the temperature of the air, the processes of vegetation, and the habits of animals, — these are circumstances too obvious and striking to have escaped attention, or not to have awakened curiosity. Accordingly, it is only reasonable to consider their thoughtful observation as coeval with the primitive age of man. We may undoubtedly regard the great levels of South-western Asia — the country between the Nile and the Euphrates — the cradle of mankind — as the birth-place of the science, and the scene of its first culture. Though no original memorials have been preserved of the facts noted, nor of the progress made by the earliest inhabitants of that region, yet the references made by subsequent historians show ing their devotion to the study of the heavens, and the reputation assigned to them for such pursuits by the unanimous voice of antiquity, long after the downfal of the Chaldean monarchy, may be accepted as sufficient proof of an inquisitive eye having been cast from that quarter upon the objects and movements of the firmament. The district possesses many natural advantages for observation ; a climate not subject to sudden variations, a serene sky, an open horizon, and a remarkably transparent atmosphere. Upon a winter night in our northern latitude, the spectacle is brilliant that is unfolded over the head of the traveller by the unclouded heavens, as he emerges from the smoke of the city into the clearer air of the country ; but the mild beauty of the moon, the vivid sparkling of the stars, and the intense darkness of unoccupied space, present a far more glorious exhibition, as seen through the purer medium of an eastern clime ; and nothing more forcibly arrests the attention of the European than the magnificent canopy which the eventide unveils to him, on first visiting the oriental deserts. Besides the striking garniture of the sky, the occupations of man in the more primitive times — the warfare of the huntsman by night and by day — the custody of flocks and herds, wandering in solitary places, and requiring the shepherd's vigilance to protect them from the beasts of prey, — together with the influence of the revolving seasons, coincident with celestial changes, upon the flowers of the field, the trees of the forest, and the productions of the vineyard — would com bine to stimulate interrogation respecting the vault of heaven, the meaning of its visual glories, and the laws of their movement. From the book of Job — in all probability the record of some pastoral chief migrating at an early period on the plains near the Euphrates — we gather indications of the heavenly bodies having attracted the watchful observance of mankind. Though it may be doubtful whether our version rightly renders the asterisms named by Arcturus, Orion, and the Pleiades, it is obvious, from the tenor of the passages in which they are intro duced, that principal constellations or single stars are intended. The temple of Bolus at Babylon, coeval with the foundation of the city, whose ruins are identified with those now extant of Birs Nimrood, is supposed to have been devoted to an astronomical as well as an idolatrous purpose. Its reported construction would seem to intimate this, being of a pyramidal form, with its four faces opposed to the four cardinal points of the horizon. Upon the summit, according to the Greek historian, the Chaldean priests contemplated and exactly noted the risings and settings of the stars. ERA OF THE GREEK AND ALEXANDRIAN SCHOOLS. 3 At the time of the capture of the city by Alexander, his tutor, the philosopher Aris totle, is said by one of his commentators to have received from Callisthenes a catalogue of eclipses observed there during a previous period of 1903 years. Though there may be con siderable exaggeration here, yet there is, no doubt, substantial truth in the statement, since Ptolemy gives six Chaldean eclipses, which seem to have been taken from the catalogue, the earliest of which, however, goes no farther back than the year 720 B. c., answering to about the time of the first captivity of the Jews. A comparison of these ancient with modern observations led Halley to the discovery of the doctrine of the moon's accelera tion — that is, that she now moves round the earth with greater velocity than formerly, the cause of which Laplace has satisfactorily explained. Ptolemy distinctly refers to Chaldea as furnishing the best and most numerous astronomical observations ; and Cleo- medes, speaking of a peculiar eclipse of the moon, states that " no astronomer, whether Chaldean or Egyptian, has ever recorded one of this kind." It is remarkably illustrative of the habit of diligent observation, that the Chaldeans were acquainted with the cycle of 6585^- days, during which the moon makes about 223 synodical revolutions, and experi ences the same number of eclipses, alike too in order and magnitude, comparing cycle with cycle. To them is attributed the invention of the zodiac and the duodecimal division of the day. Superstition was the mainspring of that observance of celestial phenomena which pre vailed at an early period in the regions bordering on the Euphrates. The heavenly bodies were the objects of religious veneration. We can easily understand how, as the light of the primitive revelation respecting the Supreme Ruler faded from the mind, men fell into the error of regarding the glorious realities of the firmament as the governing intelligences of the world. Their uses in the economy of the universe ; their resplendence and incom prehensible character, to the untutored observer ; their elevation and far removal from man ; their regular disappearance and return ; their stability and undiminished lustre ; — these are circumstances upon which popular ignorance would be likely to fasten, convert into intimations of intelligent existence, and establish thereby the worship of the stellar orbs. Such, in subsequent ages, has been the effect of the impressive appeal, made by the great lights of heaven to the physical eye, in the absence of information. Even in our day many a savage falls prostrate before the rising sun, or honours with religious ceremony the different phases of the moon. The supposed possibility of divining future events by the appearance of the heavens, was another inducement by which the ancient mind was powerfully actuated to observe the face of the sky — a hollow but imposing superstition, springing out of the witnessed regularity of the effects produced upon the face of nature by the heavenly bodies. The apparent varying altitude of the sun, at different times of the year, affecting the earth with different degrees of heat as his rays are more or less oblique, producing thereby the pheno mena of the seasons, was one of the physical facts open to the notice of the early observers. They saw not only the day and night of the world, but the summer and winter of the world's year, through which vegetation quickens, flourishes, and dies, determined by the move ments of a mighty luminary in the firmament ; and the supposition was not unnatural, in a connection so close and marvellous, that the sun was an intelligent body appearing in certain positions to prognosticate certain events. The office supposed to be performed by one of the heavenly bodies was also assigned to the rest, and the connection observed between them with the changes upon the surface of the earth was likewise extended to every class of circumstances, even the physical and moral qualities of men ; and thus, in the observation of effects regularly occurring, their true causes overlooked, but being plainly dependent upon celestial appearances, the art of judicial astrology had its origin. The Chaldean priests marked the position of the stars in their courses, and of the moon 4 HISTORY OF ASTRONOMICAL DISCOVERT. walking in her beauty, for astrological purposes ; and hence inspired prophecy, when denouncing the divine judgments against Babylon, challenges the "astrologers, the star- gazers, and the monthly prognosticates," to try their power to avert them. The pre dominance of this delusion during the middle ages in Europe, transported hither from the East, is well known. The fate of empires, the destiny of monarchs, the consequences of battle, the private fortunes of individuals might, it was supposed, be gathered from the position of the stars at the time of the nativity of the persons on whose behalf they were consulted, compared with their position at the time of the consultation ; and with out applying to the seer, who was imagined to read in the heavens the character of every event, whether it would prove favourable or adverse, scarcely any public measure or private enterprise was undertaken. The honour of priority in observing the celestial sphere has, however, been claimed for the ancient Hindus, the Chinese, and the Egyptians ; and to the two former especially, a cultivated knowledge of its mechanism at a far distant era has been assigned. It would involve a tedious and unsatisfactory detail to consider this question at length. It may suffice to remark, that the preponderance of evidence is in favour of the plains of Chaldea being the primal seat of application to observative astronomy — that from thence, as from a general centre, it radiated, at some unknown but remote period, towards the banks of the Nile on the one side, and to India and China on the other — and that, in the in fancy of national existence in those countries, the rising and setting of the stars, lunar and solar eclipses, and conjunctions of the planets, were objects of attention, with an entire reference either to astrology, religion, or policy of state. The Hindu tables claim an epoch of 3102 years before Christ, and fix a general conjunction of the sun, moon, and planets, at that era, the beginning of the Caliyug, or iron age of their mythology ; but modern calculation proves the impossibility of such a conjunction then occurring — that Venus, in particular, could not have been near it at the time specified. The tables there fore are not established on observation, but have been calculated backwards, either from data supplied by native application in a comparatively recent age, or derived from the Greeks and Arabs. In opposition to this last conjecture, the proud scorn of foreign nations en tertained by the Brahmins has been quoted, which seems to have been special in relation to the Greeks or Yavans, from their proverb that no base creature can be lower than a Yavan ; but the following curious passage from one of their earliest astronomers upholds the former opinion: — " The Yavans," says he, "are barbarians, but this science is well established among them, and they are revered like holy sages." With reference to the ancient Chinese, we have little in their annals beyond records of solar eclipses, which were regarded as prognostics of importance to the empire. Those which may be depended upon, as having been actually observed, commence with the year 776 before Christ, and terminate with the year 1433 of our era. But nothing is more dubious than the credit of their native histories ; and nothing more certain than the ignorance of the professedly scien tific class, even of the simplest operations of practical astronomy, when intercourse was first opened with the people of the West. In Egypt, no doubt, attention to celestial phenomena commenced with the era of its early inhabitants. The exactness with which some of the pyramids have been made to face the four cardinal points has engendered the suspicion that they were designed for an astronomical use ; and authorities may be cited, who state, that they terminated at the top in a platform which the priests occupied as an observatory of the heavens. But if the Greek philosopher taught them how to find the height of the pyramids by the shadow, one of the most simple examples of practical geometry, we can form no high idea of the accomplishments of the Egyptians. In fact, Ptolemy, who lived in the country, and may be presumed to have been acquainted with its records, derived none of his materials from that source, but only quotes the observations of the Chaldeans. EKA OF THE GREEK AND ALEXANDRIAN SCHOOLS. 5 The sculptured planisphere of the temple of Denderah, discovered by the scientific men of the French expedition, and supposed to represent the appearance of the heavens at midnight on the summer solstice, about seven centuries prior to the Christian era, is now well known to be a work as recent as the time of the Roman empire. Upon the whole, we have reason to suppose that the astronomy of the ancient oriental nations made no ad vances beyond that tolerably exact knowledge of the mean motions of the sun and moon which the purposes of agriculture required, — that it chiefly dealt with the simple observ ation of eclipses, occupations, and the rising and setting of principal stars, which was the work of a priesthood who made it subservient to the consolidation of their superstition, — and that the idea of a cultivated science existing in times of venerable antiquity, the hypothesis of some philosophers half a century ago, — is without foundation. The present divisions of the sun's apparent path in the heavens, upon each of which imagination has stamped an earthly figure ; with the arrangement of the extra-zodiacal signs ; date their origin from a remote period, but both era and authors are lost in the mists of ancient time. However inconvenient their use, and undesirable, on other grounds, their retention in the present day, there was a moral grandeur in the idea of registering in the skies the wild legends of mythology, and writing upon the imperishable vault of heaven the customs and events of earth — all so surely liable to change and to oblivion. The grouping of the stars into constellations, to which definite names and figures are attached, had an oriental commencement, though subsequently the Greeks and Romans largely altered and amplified the work of their predecessors. It is not an improbable surmise, that the figures of the zodiac have some relation to the rural occupations of the ancients, or to the phenomena presented by the sun. Thus, the figure of a ram is supposed to have been assigned to the assemblage of stars forming the first constellation, because of the sun being in that part of the heavens at the season when the flocks were taken from the stables to the fields. Thus, also, the lion was chosen to represent the fierceness of the solar heat in summer ; the scorpion, to indicate the unhealthiness of autumn ; and the balance, to express the equilibrium, or equal length of the days and nights, at the same period. While the Greeks and Romans retained the zodiacal constellations, derived from remoter antiquity, they constituted, as extra-zodiacal, images having a special reference to their own history — the figures of heroes, and the emblems of their deeds, over whose existence hang the clouds of fable, or upon whose reported character rest the blots of shame. It must, however, be acknowledged that the moderns are scarcely in circum stances to blame this proceeding, having contributed themselves to make confusion worse confounded by adding to the motley assemblage of celestial signs. A place in the heavens has been given to the shield of Sobieski, the sceptre of Brandenburg, the crown of Frederick, the heart of Charles the First, and one was proposed for Napoleon in the height of his guilty greatness. The age of astronomy in Greece commenced in the seventh century previous to our era ; but in the writings of the older poets, Hesiod and Homer, some centuries earlier, allu sions occur which show that the appearance of particular stars and groups had been care fully noted. The former mentions the Pleiades remaining invisible for forty days, which has been found to be as accurate as possible for his epoch and latitude. In precepts con cerning rural affairs, he advises the sickle to be applied to the ripened corn at the heliacal rising of the cluster, and the ground to be ploughed at its heliacal setting. Now, sup posing that he lived about nine centuries before Christ, the era usually given, it is ascer tained, by astronomical formula?, that the heliacal rising of the Pleiades took place at a time of the year corresponding to about our seventh of May, so that the harvest in Greece is now a month later than it was then. It is also found that their heliacal setting would be at a period answering to our twenty-ninth of March. The interval between the two 6 HISTORY OF ASTRONOMICAL DISCOVERT. periods, about forty days, during which time the cluster would be invisible owing to its proximity to the sun, corresponds with the preceding statement. Hesiod likewise ob serves, that when the Pleiades rise from the dark seas, sailing is dangerous, and that, on account of violent winds and rain, it is necessary to have large vessels, well provided with ballast, and to work much at the pumps. Here, he evidently alludes to what is called the acronical rising of the stars, which takes place at the setting of the sun. This would happen in his day soon after the autumnal equinox, in the case of the group named ; and at that season, we know that storms are common in the Grecian seas. The names of several of the constellations occur in Homer. In the fifth book of the Odyssey, he makes Ulysses, upon leaving the island-goddess for his bark, speak of the " Pleiades and Bootes, the Hyades, and bold Orion, the Bear, which is called the "Wain, the un wearied sun, and the full moon, and all the stars, by which, like a crown, the heavens are surrounded." He mentions Sirius also, and Hesiod in addition introduces Arcturus ; but neither of these writers take any notice of the planets. The reference, in the fine passage descriptive of Tydides in the Iliad, is doubtful : — " High on his helm celestial lightnings play, His beamy shield emits a living ray ; The unwearied blaze incessant streams supplies, Like the red star that fires the autumnal skies, When fresh he rears his radiant orb to sight, And bath'd in ocean shoots a keener light." Some conjecture Venus to have been intended, others Sirius ; and it may here be men tioned, as a singular physical fact, that Sirius, now so brilliantly white, was known as a red star to the ancients — a change of aspect which is not a solitary instance of the phenomenon. By THALES — the founder of the Ionic school — the basis was laid, of whatever profi ciency the Greeks attained in astronomical sci ence, for they were never distinguished as a people by the study of physical nature. Of him, the familiar story is related, that when a boy at Miletus, his native city, he fell into a ditch while contemplating the stars, upon which Thressa, his conductress, exclaimed, " Why, O Thales, do you seek to comprehend the things which are in the heavens when you are not able to see those before your eyes ? " The truth of this anecdote has been doubted, but the remark harmonises with what we know to have been the general tone of the Grecian mind. The great men of the country were chiefly poets, warriors, statesmen, orators, and moral rather than natural philosophers. It was not the spirit of scientific enquiry, but a love of speculative and tasteful sentiment, that ele vated the soul of Plato into communion with the skies, and inspired the thought, that because the flight of birds, and the movement of every body through space, produced a vibrative sound, that therefore the motion of the celestial objects must occasion a ravishing harmony, fitly called the music of the spheres — an idea to which Shakspeare gives expression in the address of Lorenzo in the grove to Jessica : — ERA OF THE GREEK AND ALEXANDRIAN SCHOOLS. 7 " How sweet the moonlight sleeps upon this bank I Here will we sit, and let the sounds of music Creep in our ears ; — soft stillness and the night Become the touches of sweet harmony. Sit, Jessica ; look how the floor of heaven Is thick inlaid with patterns of bright gold : There's not the smallest orb, which thou behold'st, But, in his motion, like an angel sings, Still quiring to the young-eyed cherubim. Such harmony is in immortal souls." It was the tendency in general of the Attic mind to study with ardour, morals, poli tics, and religion, but to play with physical phenomena : regarding only the graceful and poetic sentiments they suggested. Thales, an Ionian, and his successors, were exceptions to this rule of their countrymen, and arrived at conceptions respecting the constitution of the universe which strongly sympathise with the hypotheses that are now admitted. The most prominent circumstances concerning him are, that while the Greeks were contented with the rough approximation to the north afforded by the Great Bear, he introduced the knowledge of the Little Bear, by which the Phoenician mariners had long been accustomed to steer ; that he made a near approach to the diameter of the sun, taken at a mean ; taught the sphericity of the earth ; and predicted a great solar eclipse, which occurred at the time announced. We may regard this last-mentioned particular as the greatest astronomical achievement, resting upon good authority, that had hitherto transpired. Herodotus, whose relation may be substantially confirmed by other testimonies, observes, that in the midst of an action between the Medes and Lydians, the day was suddenly changed into night. He adds, that Thales the Milesian had predicted the year in which the eclipse would happen, and that the hostile armies, when they saw the darkness, desisted from the battle. According to the calculations of Bailly, the centre of the moon's shadow passed in a right line over the north-eastern part of Asia Minor, the scene of the war, through Armenia into Persia, on the morning of September 30th, B. c. 610. Want of minuteness in the historian probably led to the statement that the prediction referred only to the year in which the eclipse would take place, for, as it was total, or nearly so, Thales must have been able to come much nearer to the time. It follows, also, that such a prediction could only have been made with certainty by one in possession of a long series of observations derived from some foreign source, as the Greeks themselves had not originated any : in all likelihood from Chaldea, where the requisite materials might be found. The opinions held by the successors of Thales are in several respects remarkably accordant with modern ideas. Anaximander maintained the tenet of the earth's move ment about its axis, and of the moon's light being reflected from the sun. Anaxagoras, who transferred the Ionic school from Miletus to Athens, in addition, offered a conjecture that, like the earth, the moon had habitations, hills, and valleys. These doctrines were taught upon a more extended scale by PYTHAGORAS, who appears to have reached the sublime conception of the earth's motion round the sun, which Philolaus, his successor in the Crotonian school, is generally believed to have taught openly. According to the Pythagoreans, not only the planets, but the comets themselves, are in motion round the sun, and not floating meteors formed in the atmosphere. But these were the conjectures merely of sagacious minds, not possessed of the evidence requisite to give prevalence and stability to opinions, while they were directly opposed to the testimony of the senses. Hence, instead of obtaining the suffrages of antiquity, they met with little acceptance ; and for eighteen centuries, the apparent motions of the heavenly bodies were regarded as unfold ing the true constitution of the universe. A blind submission was yielded for ages to the dogmas of the Aristotelians, who held the earth to be the quiescent centre of the universe, the a HISTORY OP ASTRONOMICAL DISCOVERY. celestial bodies its servants, moving in circular orbits, and with uniform velocities, and comets simply meteors gene rated in the terrestrial atmo sphere. The "divine" Plato in deed, the master of Aristotle, is said to have renounced his opinion upon one of these points in his old age, and to have admitted that the centre ought to be appropriated to some more noble object than the earth, or, rather, than ter restrial substance. It is a plausible conjecture, that the elements of his own system were first suggested to the mind of Copernicus by notices of the opinions of the disciples of Thales and Pythagoras. They won few converts, how ever, among the Greeks, and in some instances exposed their professors to persecution. The Athenians condemned Anaxagoras to death for his philosophical views, a fate from which he was saved by the interest of Pericles, but he was sentenced to perpetual banishment, and died in an obscure town on the Hellespont. Philolaus also suffered persecution on account of his doctrine of the earth's annual revolution, which so shocked the prejudices of men as to subject him who maintained it to the suspicion of impiety. Egypt became the chief seat of astronomical science in the ancient world soon after the age of Aristotle. Alexandria had risen by the delta of the Isile at the command of the conqueror from whom its name is derived, and under the superintendence of the architect who proposed cutting mount Athos into the figure of a man. Upon the death of Alexander it became the capital of one of the kingdoms formed out of the ruins of his empire. The first of the Ptolemies laid the foundation of its celebrated library — perhaps the most extensive collection of books ever brought together before the invention of printing. His successor established in connection with it a college for the cultivation of the pure sciences, invited the most accomplished of the Greeks to repair to it, supplied them with whatever instruments could be furnished necessary to their pursuits, and thus arose the Alexandrian school, which received the flattering epithet of Divine, on account of the acquirements of its professors, and the philosophical character of its investigations. It originated a connected series of observations relative to the constitution of the universe. The positions of the fixed stars were determined, the paths of the planets carefully traced, and the solar and lunar inequalities more accurately ascertained. Angular distances were calculated with instruments suitable to the purpose by trigonometrical methods, and, ultimately, the school of Alexandria presented to the world the first system of theoretical astronomy that had ever comprehended an entire plan of the celestial motions. The system we know to be false, and inferior to the Pythagorean notions ; but it had the merit of being founded upon a long and patient observation of phenomena, a principle which finally brought about its own destruction, while the previous theories were the results of pure hypothesis. ERA OF THE GREEK AND ALEXANDRIAN SCHOOLS. The most interesting circumstances connected with the early history of the Alexandrian school are the attempts made to determine the distance of the earth from the sun, and the magnitude of the terrestrial globe. Aristarchus of Samos is the author of an ingenious plan to ascertain the former. Suppose the centre of the circle s to represent the centre of the sun, M that of the moon, E being the position of an observer on the surface of the earth. It is easy to perceive that, when the moon has half her disc illuminated by the sun, a line drawn from E to M will be perpendicular to another line drawn from s to M, making with each other a right angle. The plan of Aristarchus was, that the angular distance s E M should at that time be taken, which is possible, because both the sun and moon may then be seen at once above the horizon, from whence the ratio of E s to E M may be determined. He obtained the general result, that the distance of the sun from the earth is about nineteen times as great as that of the moon from the earth. We now know that the distance is much greater; but notwithstanding the inaccuracy of the result, the method employed is undoubtedly just, and reflects the highest honour upon the genius of its proposer. He failed in practice, owing to the difficulty of ascertaining the exact time of the bisection of the moon's disc, and the imperfect instruments then in use for the mea surement of angular distances. The determination of the sun's distance from the earth, with any thing like precision, is only of recent date, and has been effected by means of which the ancients could have had no conception. Aristarchus held the Pythagorean doctrine of the motion of the earth in space, and gave the right answer to the formidable objection long afterwards made to it, that of the non-existence of an annual parallax. The answer recognised the earth's orbit as being an insensible point in comparison with the vast distance of the fixed stars. The boundaries of the universe were thus extended to his mind far beyond any limits conceived by his predecessors. There is great obscurity resting upon his life. The era of his birth and death is unknown ; but he was alive B. c. 280, as an observation of the solstices made by him at that date has been preserved. The Greek text of his only surviving work, " On the Magnitudes and Distances of the Sun arid Moon," was edited in this country by Dr. Wallis in 1688. He estimated the apparent diameter of the sun at 30', — about 2' too little. The attempt to determine the magnitude of the earth was made by Eratosthenes, and we have reason to believe this was the first attempt ever made to solve the problem, as certainly it was to do it upon a true principle. Syene, in Upper Egypt, then a flourishing city, now Assouan, has acquired an interest from its connection with this experiment. It was supposed to lie exactly under the tropic of Cancer, as it had been observed that, on the day of the summer solstice, at noon, a well there was enlightened to the bottom, while vertical bodies threw no shadow for the space of about three hundred stadia around it. At Alexandria, therefore, which was conceived to lie under the same meridian, on the same day at noon, when the sun was believed to be vertical at Syene, Eratosthenes measured his zenith distance, or the value of an arc of the meridian between the two cities. Let E be the centre of the earth, A Alex andria, s the sun, and s' Syene. The celestial arc contained between the zeniths of the two places, Alexandria and Syene, was found to be equal to -^th of the circumference of a circle, that is, to 7° 12'. Now, admitting the earth to be of a spherical form, Eratosthenes would obtain the measure of its circumference, by multiplying fifty times the distance between the cities. This distance was ascertained by order of the government to be 5000 stadia, and consequently the result obtained for the length of the 10 HISTORY OP ASTRONOMICAL DISCOVERT. whole terrestrial circumference was 250,000 stadia. The great uncertainty that exists, as to the value of the stadium in question, prohibits any appreciation of the measurement : but several important errors were committed in the practical application of a right principle. No allowance was made for the solar parallax, and instead of Syene being under the tropic of Cancer and on the meridian of Alexandria, it is about 50' north of the former, and nearly 3° east of the latter. The principle of the method employed is, however, pre cisely the same as that which has been acted upon in modern times ; and our more accu rate results in determining the magnitude of the earth are owing to greater nicety in observation, attention to all the elements which the solution of the problem requires, and more perfect instruments for the measurement of linear and angular distances. The inventor of the method was born at Cyrene, in the year 276 B. c. The third Ptolemy invited him to his capital, giving him the charge of its library; but becoming weary of life at the advanced age of eighty, he died by voluntary starvation, and was succeeded in his office of librarian by the author of the Argonautics. We now come to the greatest astronomical name in antiquity — that of Hipparchus — who may be properly regarded, on account of the plans he pursued and the results he ob tained, as the father and founder of real astronomy. The invention of spherical trigonometry is supposed to be due to him, and undoubtedly the first application of it is, by which the places of the celestial bodies may be fixed, and the variations of their movements exhi bited with precision. He approximated also closely to the true length of the tropical year, which had been previously held to be 365^ days. This he discovered to be an error in excess, by comparing one of his own observations of the summer solstice, with another made by Aristarchus of Samos, 145 years before. His own determination of 365 days, 5 hours, 55 minutes, 12 seconds, exhibits a value greater than the truth by 6' 13" only, as according to Laplace, the length of the ti*opical year at that time must have been about 4"*2 shorter than in the present age. The error can occasion no surprise. It must be remembered, in behalf of the ancients generally — to use the words of Delambre, that their astrolabes were nothing but armillary spheres, of no great diameter, and with very small subdivisions of a degree ; and that they had neither telescope, vernier, nor micrometer. " What should we do," he goes on to remark, " even now if deprived of these helps, and if we knew neither the refraction nor the true altitude of the pole, on which point, even at Alexandria, and with armillae of every sort, an error of a quarter of a degree was com mitted ?" At this day we dispute about a fraction of a second ; they could not then answer for any fraction of a degree, and might be wrong by a whole diameter of the sun and moon. The appearance of a new star in the time of Hipparchus is said to have induced him to make a catalogue of the fixed stars, in order that posterity might be able to recog nise any changes that might take place in the appearance of the heavens. He was well aware of the importance of such a catalogue, especially for observations of the moon and planets ; and in executing the task he rendered essential service to astronomy, and made his most remarkable discovery. Comparing the place of the star Spica Virginis, as de termined by himself, with that assigned to it about 170 years previously by two distin guished Alexandrians, he found that this star was six degrees distant from the autumnal equinox, whereas the before-mentioned astronomers had found it eight degrees from the equinox. He saw that there must have been either a movement of the star in longitude during the interval, or a contrary movement of the equinoctial point in the heavens. The same phenomenon was observed in relation to other stars ; that while their latitudes had been retained unaltered, they had advanced in longitude ; and hence the retrogradation of the equinoctial points along the ecliptic was inferred, the cause of which remained a secret till the age of Newton. The catalogue formed by Hipparchus contained 1080 stars. The labour it involved, ERA OF THE GREEK AND ALEXANDRIAN SCHOOLS. 11 and its use, called forth the strong language of Pliny, who describes it as a thing even hard for a god to perform — " Ausus rem etiam Deo iniprobam." Perhaps, had we an accurate catalogue of the stars, dating back four thousand years, some remarkable varia tions of position would be discovered, transpiring by slow and imperceptible degrees, which would open views of the universe, which will now require the observations and comparisons of future centuries to develope and confirm. After determining the places of the stars, Hipparchus made a representation of the heavens on the surface of an artificial globe, which appears to have been deposited at Alexandria ; and with him also the happy idea originated of marking the positions of towns in the same manner, by circles drawn through the poles perpendicularly to the equator, or by latitudes and longitudes. When his brilliant career commenced and terminated, is unknown ; but he was born at Nice, in Bithynia, made many of his observations at Rhodes, and was alive in the interval between 160 and 125 B. c. He amply merited the epithet applied to him by Ptolemy, " the lover of labour and truth," ^iXoTi-ovoc K-CH tXa\7/9/7e ; and is properly classed in scientific opinion with the Brad- leys and Flamsteads of modern times. After him, there is little to invite attention in the history of as tronomy for nearly three centuries, when we come to Ptolemy, the first who formally broached a system of the universe which has been handed down to us. Apart from his theory, Ptolemy i has great merits. He was the best scholar of his age — a practical astronomer, mathematician, and geographer — the author of the im portant discovery of the evection or libration of the moon. Born in Egypt, and flourishing at Alexan dria through the reigns of the em perors Adrian and Antoninus, he there became acquainted with the writings and observations of Hip parchus. The former, with one exception, unfortunately perished at the destruction of the Alexandrian library; but the chief of the latter have been preserved by Ptolemy in his own works, and they have largely contributed to his fame. In a celebrated production which ruled the mind of Europe for fifteen centuries, the Great Collection, or Almagest, as it was called by the Arabic translator, he re corded the advances of past ages in astronomy, the state of the science in his own time, and developed a plan of the celestial movements. It recognised the earth to be a spherical body for reasons similar to those that are now alleged in proof of its convexity — to be the immovable centre of the universe — the sun, moon, planets, and fixed stars, prosecuting a daily revolution around it, in perfect circles, and with uniform velocities. This is in accordance with the appearance presented by the first blush of the universe to the physical eye. The sun is seen daily pursuing a course through the heavens in the segment of a circle from cast to west. The same path is ap- 12 11I3TO1U' O? ASTRONOMICAL DISCOVKKT. parently described by the moon and stars ; and on a calm autumnal or winter night, when the winds are lulled, and scarce a twig stirs, or a ripple is seen upon the waters, but the " river wanders at its own sweet will," how perfect the illusion in which the scene involves the senses — the quiescence of our terrestrial globe, and the ceaseless revo lution of the firmament round it as a central point ! These were dogmas firmly held by the Platonists and Aristotelians, who stoutly clung also to the idea of circular orbits and uniform velocities in relation to the celestial luminaries ; because the circle was deemed the most perfect of all geometrical figures, and on that account alone proper to represent their motions ; and be cause of the fancy, that in such divine and eternal bodies no irregu larity can exist. We have seen, however, that the Greeks had a cultivated acquaint ance with other movements besides the apparent diurnal revolution of the sphere, movements in an opposite direction to it. They had carefully traced the sun's path in the eclip tic, that of the moon in her orbit, and they had marked likewise the striking peculiarities of planetary motion. To an observer on the earth, the planets appear to pursue a course of the most irregular and unsystematic kind, which was a perfect puzzle to the ancient theorists. Sometimes they seem to go along with the sphere, but with greater celerity; then, to remain stationary; then, to retrograde, or make an angular movement, or describe a circuit like a loop in a knot of ribbons. The paths of Mars and Jupiter, as observed from the earth, described the courses roughly represented in the diagram, at the intervals stated. It seems surprising therefore, in the face of these appearances, that the centrical station of the earth, and all the orbs of heaven moving round it in perfect circles, should have become so much the grand leading idea of the ancient mind. Hipparchus, indeed, was too well aware of the imperfection of observation, and of the importance of supplying data upon which to found a theory, to be given to theorising himself. But when he did systematise, he departed from one of the cardinal maxims of his compeers and succes sors, by supposing the sun to revolve round the earth in a circle, the earth not being at the centre. He had found the in terval between the vernal equinox and the summer solstice 94^ days, and that from the summer solstice to the autumnal equinox only 92£- days, thus making the length of the summer half year 187 days, and that of the winter half year 178 days. To account for this unequal division of the year, and to reconcile it with the idea of the sun's orbit being a circle and his velocity uniform, Hipparchus dismissed the hypothesis of the centrical position of the earth. He supposed an eccentric circle, according to which, A B c D may represent the solar orbit, E the place of the earth, not coincident with F the centre of the orbit. E F will be the eccentricity, G H the line of the apsides, i the position of C The Moon. 5 Mercury. $ Venus. © Sun. J Mars. } Jupiter. I? Saturn. * Fixed Slurs. ERA OF THE GREEK AND ALEXANDRIAN SCHOOLS. 13 BL the sun at the summer, and j at the winter solstice, K his place at the vernal and L at the autumnal equinox. This theory provides for the circular orbit and uniform velocity of the sun ; for the unequal division of the year, and an apparently unequal rate of motion to a spectator at the earth ; for the two arcs formed between K and L are unequal, and I j it is perfectly obvious that if perceptible to a terrestrial observer the sun would appear to travel fastest at the nearest point of the apsis, H, and slowest at the farthest, G. This scheme is chiefly remarkable for its removal of the earth from the post of honour in relation to the solar orb, which the general voice of antiquity assigned to it with reference to the whole uni verse, that of being the centre of all the celestial revolutions. The idea of his great predecessor was not admitted by Ptolemy, who contended for the immobility and centrical situation of the earth, and attempted to reconcile with these po sitions, and with the dogmas of perfect , circles and uniform velocities, the diverse and complex movements in the heavens. In explaining the irregularities of the planetary courses, he adopted largely the hypothesis of epicycles ; a scheme based upon the general principle, that irregularities of movement may be resolved into a combined series of regular movements — a sagacious idea, not however his own, but proposed by some of the earlier Greeks, yet one which he was the first laboriously to apply to the phenomena ob served. It is demonstrable that two motions, each uniform in itself, may, in combination, appear vexed and tortuous. In illustration, Dr. Nicliol says, suppose that a ship were sailing evenly and uniformly along a coast ; it is manifest that a passenger standing on deck would appear to a spectator on shore to move past him also in a regulated and uni form manner, with the same velocity as the ship ; but if, instead of standing, the passenger should walk to and fro on the vessel's deck, likewise with a constant pace, his actual motion along the coast would clearly seem of the most irregular kind. While walking from stern to prow his motion would appear faster than the ship's; and when walking from prow to stern, it would, on the contrary, appear slower ; nay, if in this latter case the passenger walked faster than the ship sailed, he would appear for a certain time to go along the coast the other way ; so that if the vessel were invisible, and the observer fixed his attention solely on the passenger, he would see very irregular motions ; sometimes accelerated, sometimes retarded, sometimes even retrograde — all, however, flowing from the mere combination of two uniform motions, the sailing of the vessel and the walking of the passenger. Now, Ptolemy's theory )c of epicycles combines two movements in the heavens, that of a centre and a circumference. Thus let E be the earth, and M an imaginary centre in the heavens : the planet is supposed to be moving around it in the circumference abed all the while the imaginary centre is accomplishing the orbit A B C D. A little attention will soon discover that upon this hypothesis the planet's motion will appear at times direct, stationary, and retrograde to an observer on the earth. But though the assumption satisfies some of the conditions required by the problem of the planetary movements, it goes a very little way towards answering them all, and Ptolemy was obliged to crowd cycle upon cycle, and combine them with eccentrics, in a manner that would be difficult to make intelligible, and useless if attempted. It was a blind adhesion to the physics of Aristotle — an unquestioning adoption of the false principle respecting circular motion being the law of nature and the earth the centre of the universe — that led to this complicated scheme to harmonise its apparent movements. These fundamental errors being admitted, it necessarily followed that the mind must go forth in quest of some plan, to bring into coherence with the maxims 14 HISTORY OF ASTRONOMICAL DISCOVER!. adopted the observed facts of planetary motion. The acute intellect of the ancients is illustrated by the theories proposed ; but the lesson is strikingly furnished by their labo rious and abortive efforts, that it is folly to take for granted that which has not been proved. The later Ptolemaists occupied themselves for centuries in amplifying and mend ing his system, supplying an epicycle here where it was wanted, and an eccentric there when required, and even converting his imaginary spheres into solid transparent wheels, re volving the one within the other, and each carrying a planet attached to it. The profound of space was crammed with a succession of huge globular forms, in which the planets were placed, all of the finest crystal, else the light of the stars had been intercepted ; beyond these was the vast sphere of the fixed stars, crystalline likewise ; beyond that was the primum mobile, incessantly rolling and giving motion by its friction to the spheres in its concave ; while still farther out was the empyrean heaven, or paradise of blessed souls. The illustrious Alexandrian is not, however, to be identified with those who bore his name in the middle ages. He would have repudiated at once their vain inventions. They were schoolmen chiefly, more. familiar with the dreamy philosophy of the Academy and Stoa than with the experimental science of Hipparchus — more skilled in logic than in the examination of physical nature. The Ptolemy of the early Christian era was a practical astronomer, and his merits as such give him a title to fame, which his theory, now exploded and obsolete, ought not to obscure. He was the first to point out the effect of the atmosphere in changing the direction of the rays of light ; and, though unable to appreciate the amount of its refractive power, he clearly perceived its influence on the altitudes of the stars, was aware of its increase with the distance from the zenith, and assigned this as the cause of the greater apparent magnitudes of the solar and lunar discs at the horizon — an explanation now generally held. A scheme nearer to the truth than the Ptolemaic, commonly called the Egyptian, was in vogue when the former was broached, though there is no reason to suppose, with some, that it prevailed at an early period in that country. It regarded the inferior planets as revolving round the sun, and moving, in conjunction with the sun, round the earth. It is obscurely hinted at by Pliny ; but explicitly announced by Vitruvius, who lived a short time prior to Ptolemy. Mercury and Venus, the architect remarks, are the planets nearest to the rays of the sun, and move round the latter as a centre, appearing sometimes progressive, sometimes retrograde, and occasionally stationary among the signs. But this system, the prototype of the Tychonic, never became popular. A valid objection to it was probably found in the fact that the inferior planets were never seen in phase, an appearance which would be exhibited if alternately beyond the sun and between it and the earth ; a position strictly true, and had the eye at that period been aided by the telescope, Venus would have been seen in phase as at present. The superior planets were invariably arranged by the ancients in the same order — that which now obtains. They had obviously no guide as to their respective distances from the earth, but the indications discernible in their different brightness and velocity. Those which had the slowest apparent movement were concluded to be the most remote. Hence Saturn, a dull and sluggish traveller in space, was placed on the exterior ; then Jupiter and Mars followed in succession towards the earth : the sun, moon, and inferior planets were placed within the orbit of Mars, and the moon was considered the nearest celestial object to our globe. Next to eclipses of the sun and moon, occultations of the stars and planets by the moon, or the approach of the moon or of a planet to any star, with the appearance of comets, attracted attentive observation. An occultation of Mars by the moon is men tioned by Aristotle, and one of Saturn is recorded by Ptolemy as having taken place in the year 228 B. c. In fact, we may find some notice, more or less distinct, taken by the ancients, of all the celestial phenomena which the unaided vision has observed in modern ERA OF THE GREEK AND ALEXANDRIAN SCHOOLS. 15 times, with one exception, that of an annular eclipse of the sun, with reference to which the voice of antiquity is silent. The instruments of observation known to the ancient world were of a simple and imperfect kind. The earliest of which we read is a vertical pillar employed to determine the sun's altitude by means of its shadow. It was in general use for this purpose among the Oriental nations. The lofty pyramidal stone which Diodorus Siculus describes as hewn out of the mountains of Armenia by order of Semiramis, and set up in a conspicuous part of the city of Babylon, is conjectured to have been erected with this design. A Chinese record of uncertain date, but undoubted antiquity, refers to an observation on the length of the meridional shadows cast at the times of the summer and winter solstices by means of a vertical pillar. It is scarcely to be doubted that such a simple and obvious way of approximating to the length of the year must have suggested itself at a very remote period. The greatest elongation of the shadow cast by the pillar at noon at mid winter, its gradual decrease towards the vernal equinox, its greatest declension at mid summer, and its gradual advance to its maximum elongation again, are points to which we may believe attention was early directed ; and a series of observations, taken with precaution, would lead to some results valuable in a rude state of society, and to an agricultural people. The same in strument was also employed to divide the day into equal parts, by means of lines traced on the pavement, which in dicated the hour as the shadow of the column fell upon them. There is strong reason to believe that these instruments originated the obelisks of a subsequent age, erected in open squares in the Asian cities, and near the entrances of the Egyptian temples, and that these were intended primarily to answer one or all of the purposes named. It has been ob jected to this idea that the form of the summit of the obelisk will not allow of the extremity of the shadow being accu rately denned ; but there is some founda tion for the surmise that a ball crowned the summit, by which the end desired might be gained. Augustus removed two grand obelisks from Egypt to Rome expressly to be used as gnomons, which conveys the impression that they had previously served that office ; and Manlius placed a ball upon the obelisk erected by him in the Campus Martius, with a view to facilitate the accurate delineation of its shadow. The great importance in astronomy of precisely ascer taining the hour of any phenomenon occurring, or observation being made, led to various forms of the sundial, and to the construction of instruments for measuring time by night and by day when the sun was obscured. The one in general use was the clepsydra, or water- clock, as its name imports, an hour-glass, water being used prior to sand. The orations of the Greeks and Romans were regulated by this contrivance as to their time of speaking, which was called pleading by the clepsydra. The Tower of the "Winds at Athens, other wise styled the Tower of the Clock, an edifice of the age of Alexander, seems to have Obelisk at Ileliopolis. 16 HISTORY OF ASTRONOMICAL DISCOVERT. been erected to contain a sundial with eight faces, meeting the four cardinal and four intermediate points of the horizon, and a clepsydra; and, by an ingenious contrivance, it would appear that the latter was sometimes made to divide the day into twelve equal parts, the aperture through which the water flowed contracting or enlarging according as the length of the natural day increased or diminished. A great variety of instruments were constructed by the Alexandrians. Astrolabes, or annillary spheres, were used in the observance of solar and sidereal phenomena. These, in the hands of the Arabs, at a subsequent period were largely improved, and made upon a gigantic scale. Whether any knowledge was possessed of the means by which the natural sight is now assisted in the contemplation of distant objects, is a controverted topic. From some obscure intimations found in the ancient writers of bodies circulating in the universe invisible to the naked eye, it has been conceived that the satellites of Jupiter and Saturn arc meant, having been discovered by the aid of instruments analogous to the telescope. Sir W. Drummond assigns a knowledge of that instrument to the Greeks, Chaldeans, and Hindus ; but though some strong facts may be quoted in favour of the former, the evidence is not sufficient to warrant the inference. In enabling the eye to bear the brilliancy of the solar light, when directed towards that luminary, various methods were adopted. Aristotle speaks of mirrors being used in his time, probably meaning thin metallic plates finely polished. Ptolemy mentions vessels of oil being employed in viewing eclipses, and Seneca i-efers to the medium now common, that of smoked glass. We now take leave of the ancient world, bewildered by the apparently involved and disorderly movements of the heavens, having hold of no clue by which to arrive at the discovery of their harmony, "puzzled with mazes and perplexed with errors." The economy of the universe was a sealed book to the eye of antiquity — the theory of its best scholar a dream, at utter variance with the truth. The book had been shut for thousands of years previous, and it remained closed for more than a thousand years afterwards. Yet there were not wanting some lofty minds who clearly perceived the discordance between the interpretation given and the facts observed, after all that ingenuity and application had done towards a reconcilement, and who seem to have indulged the anti cipation of the appearance of a person able to open the volume and read the perfect coherence of its contents. Such was Seneca the philosopher. " How many things," he remarks, " are beyond the reach of human intelligence ! and how small is the part of the universe accessible to our knowledge ! even the Deity himself is no better known to us." But, as if inspired with the spirit of prophecy, he observes : — " The time will come when posterity will be surprised that we could be ignorant of things, the knowledge of which might have been so easily acquired, and some one will at length arise who shall teach men the paths of the comets, their magnitude and number, and why they deviate so far from the routes of the planets." How has the anticipation been realised — the prophecy been fulfilled ! It is somewhat remarkable that he who in his Natural Questions thus expressed himself, should, in a similarly happy vein, have treated another topic in the tragedy of Medea as follows: — "Eras shall come in late years, in which ocean may loosen the bonds of things, and a spreading continent expand, and Tethys reveal new regions, nor Thule be the boundary to the lands." If the former passage strongly reminds us of Copernicus and Halley, the latter does so equally of Columbus and Vasco de Gama. ERA OF COPERNICUS, TYCIIO BRAKE, KEPPLER, AND GALILEO. O rule the nations with imperial sway, to impose terms of peace, to spare the humbled, and to crush the proud, resigning it to others to describe the courses of the heavens, and explain the rising stars ; this, to use the words of the poet of the JEneid in the apostrophe of Anchises to Fabius in the Shades, was regarded as the proper province of a Roman. The genius of the people was even more adverse to the cultivation of the physical sciences than that of the European Greeks ; and we have seen that the latter left experi mental philosophy chiefly in the hands of the Asian and African colonists. The elegant literature and metaphysical speculations of Athens, her epics, dramas, histories, and orations, had a numerous host of admirers in Italy, but a feeling of indifference was displayed to the practical science of Alexandria. This repugnance of the Roman mind at home to ma thematics and physics, together with the prevalence of its military despotism abroad, which extended from the Atlantic to the Indian Ocean, from Northern Britain to the cataracts of the Nile, annihilated in a measure the pure sciences in the conquered districts where they had been pursued, and prohibited attention to them in the mother country. Long, indeed, after the age of Ptolemy, the school in connexion with which he flourished, re mained in existence ; but, receiving no countenance from the imperial representatives, and the iron yoke of arbitrary power prostrating the energies of the people, it gradually waned, and was finally extinguished by the disorders that broke up the Roman empire. The interval between the overthrow of ancient civilisation by the rude and warlike tribes that took possession of its seat, and the revival of learning, exhibits an entire neglect of the liberal arts, with the exception of the Arabs during the era of their power on the banks of the Tigris in the East, and the Guadalquiver in the West. The brilliant career of these Children of the Desert, soon after their emergence from it, was marked by an act, committed in the fever of fanaticism — the destruction of the Alex andrian library, which betokened little the literary and scientific ardour of their descend ants. The event strikingly contrasts with that which occurred in the reign of Almamon, 18 HISTORY OF ASTRONOMICAL DISCOVERT. when a long train of camels entered the gates of Bagdad laden with volumes of imported learning, the fruit of a treaty made with the emperor of the East which imposed upon him the condition of furnishing copies of all the Greek authors. The medicine of Galen, the metaphysics of Aristotle, and the astronomy of Ptolemy, thus came into the hands of the caliph, and speedily appeared in the language of the caliphate. Arabian cultivation commenced with the dynasty of the Abassides, or the middle of the eighth century. Three princes in succession, Almansor, Alraschid, and Almamon, used every means in their power to promote the growth of learning among their people, and the advantages sup plied by their fine climate were not lost upon the followers of the Prophet, when a taste for astronomical science had been created ; for upon the same sites where the old Chaldeans, two thousand years previously, had gazed with wonder upon the heavens, they entered upon a course of observation, with all the ardour common to their impulsive character, guided by the light of the Greek results. The work of Ptolemy was their text -book ; his system, theirs : but instruments were constructed upon a larger scale ; his determinations were subjected to a rigid examination ; and in many instances a more accurate conclusion was obtained. The length of the tropical year was found within a few seconds of the truth. A degree of the terrestrial meridian was measured in the Desert near Palmyra, to verify the value obtained by Eratosthenes. The obliquity of the ecliptic was determined. The great inequalities also of Jupiter and Saturn are marked in the tables of planetary motions constructed by the Arab astronomers. Their observations, in general, of the celestial bodies have a greater degree of accuracy than those of the Greeks, on account of the necessary correction being made for the phenomena of refraction, which was observed with reference to bodies near the horizon. Bagdad, however, was only the centre of a move ment in favour of science. The impulse extended as wide as the language and profession of Islam, to Egypt, Morocco, and Spain ; and it long survived after the political power of the Eastern caliphs, which had gleamed like a meteor, had as suddenly vanished. An observatory was erected in the northern part of Persia, by a descendant of Gengis-Khan ; and Ulugh Beg, a prince of the house of Timour, erected one at Samarcancl, where he compiled his now extant catalogue of the stars. The preface to this work states that eight stars marked in the catalogue of Ptolemy could not then be found in the heavens. This may have arisen simply from a mistaken entry in the first instance ; but, if a case of real disappearance, it is far from being the only one, though a profound mystery. Arabian cultivation attained its meridian splendour in Spain at a period when the rest of Europe was plunged in darkness. Through intercourse with the Moors of that country, some gleams of light gradually radiated through the Continent ; and undoubtedly they are to be regarded as having transmitted the torch of civilisation from antiquity to modern ages. Among the first fruits of their influence, the construction of the Alphonsine tables may be placed, a work of the king of Castile of that name, chiefly confined to a more accurate determination of the motions of the sun and planets, and the length of the year, the materials for which were derived from his Mahommedan neighbours to the south. There is little to detain us of any interest or importance in relation to astronomy, at this era, in countries where it has now arrived at such marvellous perfection. Observers abounded in the middle ages ; but their midnight watchings of the great canopy of heaven had very generally only an astrological purpose in view. Spcculatists were numerous respecting the mechanism of the universe ; but blindly adhering to the doctrines of the earth's immobility, and of the uniform and circular motions of the celestial lights, they laboured hard, but in vain, to adjust observed phenomena with preconceived theory. The Aristotelian notion of the spheres was revived in all its grossness, and huge materialities were conceived to constitute the eternal paths of the bodies composing the solar system, necessary to the end of keeping them in place. To account for all the celestial move- ERA OF COPERNICUS, TTCHO BRAHE, KEPPLER, AND GALILEO. 19 ments, several of these solid spheres were required to be in attendance upon the same body, and to be of various structure ; and they were multiplied and shaped, until a system was imagined which it fairly baffled the inventors to comprehend. The remark of the Castilian monarch respecting this intricate and cumbrous architecture was not without some justification, though breathing an irreverent spirit : " Had the Deity," said he, " consulted me at the creation of the universe, I could have given him some good advice." The presumptive evidence against the truth of the Ptolemaic theory is admirably, though not professedly, expressed by Milton, in the representation of Adam reasoning, How Nature, wise and frugal, could commit Such disproportions, as the supposition of the revolution of the firmament round the earth involves. It must then travel, as he argues, "spaces incomprehensible," the " swift return diurnal" implying a swift ness not to be described or imagined ; and when the phenomena of the celestial appearances are accounted for, and day and night produced, by the simple rotation of the earth upon its axis, and its translation in space, the presumption is strong, that " Nature, wise and frugal," would never " commit such disproportions," as the theory of terrestrial repose and firma- mental movement supposes. But it is difficult for the mind to disengage itself from the force of a universal opinion, especially when it is sanctioned by a venerable antiquity ; and hence, it was not until some time after the era of Copernicus, and not until after many a battle in behalf of the faith of past ages, that his system, beautiful for its simplicity, and now demonstratively proved to be correct in its leading features, received the credence of mankind. It was reserved for this great man, born on the banks of the Vistula, to deviate from the path of his predecessors, to renounce allegiance to the speculative physics of Aristotle, and to point the way, though with a cautious footstep, to the true system of the universe ; a labour which occupied upwards of thirty years of his life, one of the most glorious achievements that has marked the page of human history. He it was who revolutionised for ever the face of astronomical science, and in the magnificent language of one of his immediate followers, " commanded the sun to stand still, moved the earth from its foundations, stopped the revolution of the firmament, and subverted the whole ancient order of the universe." NICHOLAS COPERNICUS, or ZEPERNTC, was born at Thorn, near the place where the Vistula crosses the Polish frontier, some time in the years 1472 or 1473. He was educated with an eye to his father's profession, that of medicine, but was happily diverted from it by accidentally hearing a course of lectures, which inspired him with a passion for astro nomy. He was at Bologna in Italy in 1497, studying the science under Dominic Maria, and settled for a time at Rome as a teacher of mathematics, where he established a considerable reputation. His uncle, who was a dignified ecclesiastic, bishop of Ermeland, upon a vacancy occurring in the canonry of his cathedral church of Frauenburg, appointed Copernicus to the place in the chapter, who had previously taken orders probably in Italy. Here he passed the remainder of his days, dividing his time between his ecclesiastical duties, the gratuitous practice of medicine among the poor, and astronomical researches. He went but little into company, seldom conversed except on serious and scientific topics, was mild and gentle in his manners, and steadfast in his friendships. Frauenburg is a email town on the coast, not far from the junction of the Vistula with the sea. There, in a house situated on the brow of a mountain, overlooking the waters of the Gulf of Dantzic, he pursued his enquiries into the economy of the universe in peaceful seclusion, confident that he was doing a great work for posterity to appreciate. His mind was profoundly impressed with the idea that simplicity characterises the arrangements of 20 HISTORY OF ASTRONOMICAL DISCOVERY. nature; and, struck with the want of this in received hypotheses, he seems to have come to the conclusion that such scenes of complexity could not be true representations of the heavens. It does not appear when his own views became settled; but in the year 1530, the manuscript of his work " On the Revolutions of the Heavenly Bodies" was finished. In this production he disclosed his system : the Earth, a planet revolving round the Sun in an orbit between Venus and Mars ; its rotation upon its axis producing the apparent diurnal procession of the heavens ; the complicated movements of the planets being the consequence of their own motions in space, combined with that of the Earth. It is diffi cult to appreciate fully the freedom of spirit and independence of thought displayed in thus rising superior to the prejudices of centuries, now that the truth of the system has been long settled ; neither is it easy to conceive the delight and awe which must have filled the mind of its author, when, after years of patient and intense application, he was permitted to gaze upon the mechanism of the heavens unveiled, in its simplicity and grandeur, from his mountain home at Frauenburg. The prudence of the great discoverer in propounding his views is no less admirable than his sagacity in seizing hold of them. Aware of the obstinacy with which human nature clings to its early imbibed opinions, he was careful not to rouse hostility by an abrupt dogmatic attack upon the ancient theory. He communicated privately with his friends ; Reinhold and Rheticus, astronomers ; Schomberg, a cardinal ; and Gysc, a bishop. With these parties his views found acceptance. They were discussed in their respective circles, and obtained a number of converts ; not, however, without opposition, for Copernicus was satirised upon the stage at Elburg. His work, completed in 1530, was still in manuscript in 1540, notwithstanding repeated efforts to induce him to publish it. An arrangement at length was made, during the latter year, for Rheticus to furnish an account of the manu script volume; and, that being favourably received, Copernicus consented to the appearance of his own production. It was committed into the hands of Rheticus ; Andrew Osiander of Nuremberg superintended the printing, and Cardinal Schomberg bore the expense. But the illustrious author did not live to read his work in print. A copy was handed to him as he lay, a paralytic, upon his bed. He saw it, he touched it, and in a few hours afterwards expired, May 23. 1543. The cathedral of Frauenburg received his ashes without pomp or epitaph, except that upon his tombstone some spheres were cut in relief. The great square of Warsaw has a statue in honour of his memory ; and the civilised world holds his name in reverence, as one whose genius dissipated the illusions of the senses, and discovered the true astronomy. Copernicus is described as a man of ruddy complexion and light hair. A portrait, painted by himself, a half-length, came into the hands of Tycho Brahe, who made it the subject of an epigram to the effect that the whole earth would not contain the whole of the man who whirled the earth itself in ether. The scheme of Copernicus was presented to the world in the form of hypothesis. It could not be broached in any other manner, for not until the discovery of the aberra tion of the stars by Bradley, and the determination of the diminution of gravity at the equator by Richter, was demonstration given to the doctrine of the earth's rotation and translation in space. " Astronomers," he remarks, in the dedication of his work to Paul III., " being permitted to imagine circles to explain the motions of the stars, I thought myself equally entitled to examine if the supposition of the motion of the earth would render the theory of these appearances more exact and simple." But, though the resolving the apparent diurnal revolution of the sphere into the actual diurnal motion of the globe in an opposite direction was a pure hypothesis, yet we have so many examples of a real movement on our part producing an apparent antagonistic motion in other bodies, as when we sail along a river or travel on a railway, while there is something so manifestly absurd in supposing the daily revolution of the firmament, that, even if no demonstration EBA OF COPERNICUS, TYCIIO BRAHE, KEPPLER, AND GALILEO. 21 could now be offered in pi-oof of the Copernican doctrine, there is an air of truth about it sufficient to command the assent of a thoughtful mind. Proceeding upon the assumption, which was universally admitted, that the earth is a mere point when compared with the distance of the fixed stars, he very naturally remarked upon the improbability of such a vast circumference revolving in twenty-four hours, instead of the infinitesimal point by which the whole phenomena would be equally as well explained. It had been urged in support of the earth's immobility, that, if it revolved on its axis, objects on its surface would be scattered and dispersed in space by the extreme rapidity of the motion over coming the force of gravity. He did not see the true reply to this, that such effects would not take place unless the velocity of rotation was greater than the force of gravity, which was an arbitrary assumption, but still he reasonably turned the argument against the objector by observing that the diurnal revolution of the sphere of the universe would be far more likely to derange the situations of the heavenly bodies, and produce their displacement. "Why, then," he exclaims, "do we hesitate to give to the earth the mobility suitable to its form, rather than that the universe, whose bounds we do not and cannot know, should revolve ? Why should we not confess that the diurnal revolution is apparent only in the heavens, and real in the earth ? Thus JEneas, in Virgil, exclaims, ' Provehimur portu, terra?que, urbcsque recedunt.' Since, while the ship glides tranquilly along, all external objects appear to the sailors to move in proportion as their vessel moves, and they alone, and what is with them, seem to be at rest." The other conditions of the problem of the celestial motions, the sun's path in the ecliptic, are as exactly answered by the supposition of the earth's orbital motion. The annual revolution of the earth round the sun causes the apparent annual revolution of the sun round the earth ; and when we consider the vast magnitude of the solar orb, and the enormous waste of force implied in moving the greater body around the less, when precisely the same effects are produceable by moving the less about the greater, our common sense is at once enlisted in favour of the latter hypothesis as Nature's " wise and frugal" plan. The apparent eccentricities of the planets likewise, their direct and retro- gi-ade movements, that mysterious puzzle which called the epicycles of the Ptolemaists into existence, are explained upon their own principle of two combined motions : an observer on the earth in ceaseless translation sees them performing a similar orbital course, and apparent irregularity and involution are the consequences of the combined prosecution of direct and regular paths. Suppose s the sun, A u c D part of the earth's orbit in the direction of the arrow, a deb part of the orbit of a superior planet, and M N an arc of the celestial sphere, the earth is at A, and the planet at «, a terrestrial spectator will see it projected to a place in the heavens at E. The angular motion of a superior planet being less rapid than that of an inferior, when the earth is at B the planet may be supposed to be at d, and its place will be pi-ojected in the heavens at F, thus apparently retrograd ing in the sphere from E to F, while accomplishing the direct movement from a to d. The next movement of the earth. B c, and of the planet, d c, will produce a further retrogradation of the latter in the heavens from F to G ; but, when the earth has arrived at D, and the planet at b, the retrocession of the planet will appear to have ceased, and the direct movement, G ir, to have taken place. As both the earth and the planet proceed in their orbits, the planet will appear stationary among the fixed stars, then to HISTORY OP ASTRONOMICAL DISCOVERY. pursue a direct course, and afterwards to retrograde again. As an hypothesis, therefore, the Copernican theory had strong presumptive evidence in its favour, accounting for the celestial movements, and being in beautiful congruity with Nature's frugal and simple plan of general operation. Still presumptive evidence is not positive proof, nor could the truth of the theory at that time be demonstrated. It detracts not from the glory of its author, that to others the merit belongs of establishing his leading views as a real expression of the phenomena of the universe. He had not the instruments by which alone this could be done. He seems to have entertained a noble confidence that he had con ceived the true system, and that future discoveries would remove the mechanical difficulties then in its way, and a more enlarged observation of physical facts place it upon the basis of incontrovertible evidence, — a confidence which has been amply justified. The sixteenth century, rendered me morable at its commencement by the foundation being laid of true views re specting the constitution of the uni verse, was distinguished at its close by the labours of TYCIIO BKAHK, a Dane, born at Knudsthorp, near the Baltic, three years after Copernicus terminated his career. His attention was called to astronomy by a great eclipse of the sun, August 21. 1560, when quite a child. Upon being sent to the university for his education, he was accustomed to watch the constel lations while his tutor slept. Of noble extraction, and strongly influenced himself by prevailing aristocratic prejudices, he at length conquered the pride of his order, devoted himself to public usefulness in the particular department to which his natural genius was inclined, became a student, an author, an astronomical lecturer, and finally completed his offences against the pride of life by marrying a plebeian. This last step, probably, rendered exile desirable, in order to escape from the slights of his relatives. He found a welcome reception at the court of the Landgrave William of Hesse-Cassel, a prince who was himself an ardent student of astronomy, of whom it is related that, while observing the brilliant new star of 1572, his servants ran to tell him that the house was on fire : but he quietly pursued his task to its completion. The fame of Tycho has been obscured by his rejection of the Copernican doctrine, and the construction of a system of his own, combin ing the elements of the Ptolemaic and Copernican theories. He maintained the earth to be the immoveable centre of the universe, but supposed the planets to revolve round the sun, and to be carried with their centre in revolution round the earth. The adoption of this hypothesis has been usually deemed discreditable to Tycho ; but it will be only fair to recollect that the Copernican theory was, in his day, quite incapable of proof. He argued, against the diurnal motion of the earth, that, upon that assumption, a stone dropped from the summit of a high tower would not fall at the base, as we see it does, because the velocity of rotation would carry the tower several hundred feet during the descent of the stone, ERA OF COPERNICUS, TYCHO BRAHE, KEPPLER, AND GALILEO. 23 which would, therefore, fall at that distance behind it. This argument was employed by Ptolemy, who stated that, if the earth revolved with great rapidity from west to east, it would leave behind it the clouds, birds flying in the air, and, generally, all objects sus pended in the atmosphere. The answer to this is, that a falling body will partake of a rectilinear and circular motion ; the former tending to the centre of gravity, the latter proceeding in the direction of the circumference described by the point from which it falls. Gassendi tried experiments in the harbour of Marseilles, and proved, what every one now knows, that a stone dropped from the mast of a vessel in full sail will partake of the advance of the mast, and fall at its foot, as though the vessel were at rest. It may also be proved, that a stone falling from a considerable elevation, so far from being left behind during its descent, will fall in advance of the base of the perpen dicular, upon the theory of the earth's rotation. Let the circle E be the equatorial circumference of the earth, the line T a tower perpendicular to c the centre, and the circle M will then be the circumference described by the summit of the tower s, in the course of one rotation of the earth upon its axis. If we suppose the base of the tower, b, to pass to c, the summit, s, will, in the same time, pass to a, and, this being the lai-ger arc, it follows that the sum mit must travel faster than the base. Assuming, then, the earth's rotation eastward, a stone dropped from the summit will leave it with M| its momentum, and will move faster eastward, through the whole of its descent, than the base. The result will be, that it will deviate from the plumb-line, and reach the ground a little to the east of c, the foot of the perpendicular. Experiment has confirmed the accuracy of this reason ing, though obviously a very difficult matter to test, owing to the comparatively small height of buildings suitable to the purpose. Newton first threw out the idea, and cal culated that a ball would deviate about half an inch from the plumb-line, to the east, from the height of three hundred feet. Thirty balls descended from the height of two hundred and thirty-five feet, in St. Michael's tower, Hamburg, and deviated from the perpendicu lar four lines eastward, swerving also one line and a half southward, owing probably to a current of air in the tower. The experiment was, therefore, repeated in a coal-pit, in the county of Mark, two hundred and sixty feet deep. There the balls fell five lines eastward of the perpendicular, but neither northward nor southward, so that the theory of the earth's motion on its axis may now be said to have received a complete and sensible confirmation. The reason which led Tycho to reject the doctrine of the earth's orbital motion was of great force in his time. Supposing the earth to revolve round the sun, two points of the orbit will be distant from each other by the whole diameter of the orbit ; yet lines drawn from those points to the nearest fixed star discovered no appreciable angle, or annual parallax. It is sufficient to reply now, that the distance of the stars is so great as to render insensible the diameter of the earth's orbit ; but, previously to the invention of the telescope, this answer could not be deemed so satisfactory. To the naked eye the stars of the first magnitude present a diameter equal to two minutes of space. The telescope has shown this to be an optical delusion, that no star has an apparent diameter of a second. "But Tycho, knowing that if the earth moved, its change of place from one extremity of the diameter of its orbit to another produced no sensible alteration in the place of the stars, so that they must be at an enormous distance, and yet seeing them present a dia meter to the eye varying from a quarter to as much as two minutes, had little option but to assign a magnitude utterly inconceivable to the nearest fixed star, or reject the theory of the earth's motion in space. He chose the latter alternative ; and, though undoubtedly it would have been a wiser course to have paused before coming to such a conclusion, 24 HISTORY OF ASTRONOMICAL DISCOVERY. which the Copernican system as then developed might well have justified when viewed as a whole, we are not warranted in interpreting his rejection of it much to his disparage ment. The career of Tycho is far more satisfactory as a practical astronomer than as a theorist ; indeed, few men have done so much for the advance of the science, or are more worthy of praise for the amount of toil they have undergone, and the success of their labours. In the year 1572, the re markable event of a stellar apparition at tracted the attention of Europe, and excited universal astonishment and speculation. It was early in November, when Tycho, who then resided at his paternal home, observed a star of great splendour in the constella tion Cassiopeia, which he had never seen before, as he was walking across the fields about ten o'clock in the evening. It beamed with a lustre quite unwonted in that part of the heavens. It could not have escaped his observation had it previously been there. He suspected at first an optical illusion oc casioned by some defect of his own vision, but found a group of peasants gazing upon it with as much astonishment as himself. Its place he at once fixed by his instruments, and noted the fact with all its circumstances in his journal. Soon afterwards, when at Copenhagen, he found that the scientific men of the university had not observed the stranger, and excited some derision at a convivial party by mentioning the phenomenon, which, however, he soon turned into surprise by pointing out the star. One of his works is devoted to this object. The same star was observed by Cornelius Gemma, who had par ticularly examined that part of the heavens two nights previous, and was confident of its not being present then. It continued visible for the space of sixteen months, gradually diminishing in lustre, until it finally vanished in March 1574. The brilliance of this star was so great as at first to cause Tycho's staff to deflect a shadow. Its light changed from white when the brightest to a yellowish hue, and afterwards had a fiery tinge like Mars, becoming livid like Saturn before its disappearance. During the whole time of its visibility, its place in the heavens remained unaltered ; it had no annual parallax, conse quently its locality was far beyond the bounds of our system, at a remote distance in the region of the fixed stars. The appearance of a, new star had been observed in Europe about three centuries previous, and such occurrences are mentioned by the ancients ; but this taking place in a comparatively enlightened age naturally excited serious observation and inquiry. The idea of the Danish astronomer, never happy in his philosophical spe culations, was not very fortunate. He supposed that it was produced by a condensation of the matter collected in the Via Lactea, in which it was situated. The appearance of a comet in 1577 was industriously watched by Tycho, and he was led to some important conclusions. Unable to detect any sensible parallax, it became obvious that these bodies move at a remote distance from the earth, and were not, accord ing to the common opinion of the times, sublunary objects ; and observing the spheres of ERA OF COPERNICUS, TYCHO BRAKE, KEPPLER, AND GALILEO. 25 the planets cut by them in every direction, the inference was clear that the planetary spheres had no material existence. It may seem idle now to notice so absurd a notion as that of the planets moving in solid transparent spheres, but it was not so then ; and even Newton deemed it necessary to argue against the monstrous doctrine in the Principia. The labours of Tycho were also directed towards forming a catalogue of the stars, and he determined the relative and absolute positions of 777, a work inferior as to numbers to preceding catalogues, but vastly superior on account of its scrupulous exact ness. He amassed, likewise, a regular series of observations on the planets, which after wards, in the hands of Keppler, materially contributed to the framing of his famous laws. To him, also, we owe the discovery of that inequality of the moon called the variation, that of the inequalities of the motion of the nodes, and of the inclination of the lunar orbit ; and by a comparison of his own observations with previous ones, he was the first to announce the slow diminution of the obliquity of the ecliptic, which the theory of uni versal gravitation now teaches, while he commenced the systematic application to the observed altitudes of the sun, moon, and stars, of the correction required for the refraction of light. In practical astronomy the refraction of the atmosphere is an important ele ment, for, owing to it, all the heavenly bodies appear to us considerably higher than they really are. Let a b, a b, a b, a b, be strata, or layers of the atmosphere, increasing in density towards m n, the surface of the earth. A ray of light from the star s, impinging on the atmosphere, will be refracted, or bent, so as to move in the curve r r r A ; and as an object is seen in the direc tion of the ray that meets the eye, the star which is actually at s, will seem, to a spectator at A, to be in the direction c. This refraction, which always acts in a vertical direction, ••"elevates objects above their real place, and hence a body at D, below the horizon H o, will be raised and seen as if at o. Ptolemy, as has been already noticed, was acquainted with the refraction of the atmosphere, and mentions it in a trea tise on optics, but as it is not alluded to in his astronomical work, it is presumed that he had not then discovered it, and made no practical use of it in observation. The Arab astronomers, likewise, were aware of the fact through him, but to Tycho Brahe the honour belongs of calculating its effects, correcting altitudes by them in a systematic manner, and forming the first table of refractions. He estimated its amount at 34' with reference to bodies in the horizon, which is nearly correct, but erroneously supposed that it did not exist at elevations greater than forty-five degrees. This was owing to the effects of refraction above that altitude being insensible to his instruments. The urgent recommendation of Tycho to his own sovereign by the Landgrave "William, induced the King of Denmark to offer him an asylum in his own country, and an annual provision for the prosecution of his scientific pursuits. Embracing the offer, he received a grant of the small island of Hoe'ne in the Baltic, opposite Landscrona, and an annual allow ance of two thousand dollars, with the proceeds of a fief in Norway, and a canonry in the church. Here he laid the foundation of a house for himself and an observatory, which ultimately grew into a fantastic castle, resembling rather the abode of an eastern magician than the home of a sober astronomer. Uraniberg, or the castle of the heavens, expressed the large views, feudal spirit, and undisciplined mind of its architect and tenant. He was an admirable observer, had high thoughts of the dignity of his possession, never forgot his own nobility, was abundantly superstitious likewise, and unskilful at system- atising. These are characteristics plainly stamped upon the edifice which he constructed. Its front elevation, shown in the vignette, extended sixty feet in length, and seventy -five in height. It was surrounded by a wall twenty-two feet high, in the form of a square, each 26 HISTORY OF ASTRONOMICAL DISCOVK1IY. side of which was three hundred feet, and had in the middle stately gateways, with resi dences for servants. The instruments of the observatory were upon a corresponding scale. A celestial globe, upon which Tycho fixed the positions of the stars he catalogued, stood upon a pedestal five feet high, the diameter of the ball being no less than six. His whole apparatus is supposed to have cost upwards of two hundred thousand crowns. Here, in his castle, in the severe climate of the Baltic, for twenty-one years, he resided, observed and wassailed, a favourite poodle being the constant companion of his studies. Abroad, his fame extended far and wide. Kings visited his sanctuary. Our James I. spent eight days beneath his roof upon going to Denmark to attend his bride. Misfor tune, however, came soon after the death of his royal patron, and outward glory departed from Tycho. The envy of the nobles fomented dislike to the celebrated astronomer in the mind of the successor to the throne, and a personal squabble with the minister, who struck his poodle, led to his being deprived of his appointments, and removal from the island. He finally quitted his country, but Uraniberg had obtained a firm hold upon his affections, and separation from it took away the charm from life. After various wander ings, he settled at Prague under the patronage of the emperor Rudolph. There he died in the first year of the seventeenth century, leaving a name second to none in point of pure observation. Hoene was ceded to the Swedes fifty-seven years after Tycho's death — the castle of the heavens was totally demolished — its site became a green field, and even that has been blotted from remembrance. However bitter and disastrous to himself the exile of Tycho from his northern home, it was fortunate for science that it took place, as it threw into his way the enthusiastic and indefatigable Keppler, the very man in his maturity to seize hold of his materials, and draw a philosophical deduction from them. The Danish astronomer, who had previously seen one of his works, invited him to become his assistant at Prague. He appreciated his genius, hospitably supplied the wants of his poverty, taught him the habit of rigid inves- ERA. OF COPERNICUS, TYCHO BRAHE, KEPPLER, AND GALILEO. 27 tigntion, and left him the legacy of his own observations at his decease. JOHN KEPPLER, born at Wiel, in the duchy of Wirtemberg, in 1571, was educated for the church, and entered upon an ecclesiastical office, but withdrew from the science of theology to that of mathematics and astronomy, and occupied the chair of the latter at Gratz in 1 594. His native lively imagination and fiery impetuosity led him to plunge headlong, at first, into the regions of speculation ; but Tycho's advice, " to lay a solid foundation for his views by actual observation, and then, by ascending from these, to strive to reach the causes of things," — advice expressing the principle of inductive philosophy, — drew him away from pursuing the vain phantoms of fancy to conform his mind to the results of calculation and experience. His first reward was the discovery of the elliptical orbits of the planets. The Copernican system had respected the ancient reverence for the circle as the only path proper for celestial bodies to describe. An opposition of Mars, whose path is one of the most eccentric in the planetary system, led Keppler to study his motions, and among the papers of Tycho, then deceased, he found a large number of observations upon this and the other planets. He began his researches with his mind fully possessed with the idea of circular motion, but he found it utterly impossible, by any conceivable arrange ment of cycle and epicycle, to represent the known motions of Mars. The discovery came at length that the planet's path was an ellipse, the sun occupying one of the foci, the two points around which the oval is formed, instead of being in the centre. Circum stances forbid us estimating aright the labour involved in this discovery, the difficulties that arose in its progress, and the mental conflict they occasioned ; bnt Keppler describes his battles, defeats, and conquests in the following racy manner: — " While in this way I triumph over the motions of Mars, and form for him, as one completely conquered, the prison of tables, and the chains of the equations of the eccentric, intelligence is brought me from different places that the victory is all vain, and the war as fierce as ever ; for the captive enemy has broken through all the bonds of the equations, and the dungeons of the tables . . . And the fugitive would have effected his junction with the rebels, and driven me to despair, had I not suddenly brought up a new reserve of physical consider ations, the first having been beaten and scattered." Well might he think, as he tells us, of Galatea in the eclogue of Virgil, who, after inviting approach, the nearer she was approached was the more petulant in her sportive attempts to escape. The demonstration, however, of the orbit of Mars being an ellipse was finally complete, and Keppler ultimately established the fact, that all the planets describe ellipses — the FIRST of his great Laws. His next discovery was no less remarkable. While the scheme of Copernicus retained the ancient idea of the heavenly bodies describing circles, it held also the notion of their velocities being uniform. But the mass of facts accumulated by Tycho proved that the motions of Mars were not uniform — that the planets move with different velocities in different parts of their orbits ; and the inquiring mind of Keppler directed itself to ascer tain the rule which regulated their rate of motion — a bold attempt, but crowned with complete success. Let the ellipse represent the orbit of a planet, and s the sun in one of the foci. A straight line drawn from the planet at a to the focus, called the radius vector, and another line drawn from the planet at b, bound a certain extent of area, and the planet periodically passes from a to b in a certain amount of time proportioned to the area. For the sake of illustration, the time may be rated at a month. If we now draw straight lines I* from the planet at c, d, e,f, and g, other areas will be bounded, which we may suppose equal to the former, and to each other. The planet will then pass from a to b, from b to c, from c to d, and so on, in equal times or in a month. But, obviously, while the areas described by the radius vector are equal, the actual orbital path of the planet is unequal, and it must 28 HISTORY OP ASTRONOMICAL DISCOVERY. travel with greater velocity from a to b, than through the other parts of its course. This is the SECOND of Keppler's laws, technically expressed by saying that equal areas are described in equal times, to accomplish which the velocity of the planet cannot be uniform. Previous observation discovered the want of uniformity ; but Keppler found the rule which governed the phenomena, and thus did his master mind bring into conformity to law a case of apparent deviation from it. The THIRD of his laws refers to the distances of the planets from the sun. His mathematical mind caught the idea that these bodies must bear some mysterious relation to each other, and after a long and harassing pilgrimage in search of a clue to their affinity — after roaming in the wilds of conjecture, and setting the planets to music in imitation of a Pythagorean phantasy — he groped his way to the perception of a physical fact, which unfolded before him the unity of the solar system. This was the discovery, that the squares of the periodic times of any two planets are to one another as the cubes of their distances from the sun. His joy was unbounded at this discovery, as it transpired in an unexpected manner. He could hardly persuade himself that he had not been dreaming ; and it may be ranked among the most important and glorious physical truths ever reached by the intelligence of mankind. Popularly expressed, the fact arrived at is, that the distances of two planets from the sun being known, and the period or year of one of them, the period of the other may be ascertained by the above simple proportion ; and clearly does this fact involve the idea of the bodies to which it applies not being thrown at random into their places — not being independent — but members of one great system. As an example, Mars is about four times the distance of Mercury from the sun ; his period of revolution is about eight times that of the latter ; and the cube of four, or sixty four, is equal to the square of eight. Such are the laws of Keppler. They obviously confirm while they correct Copernicus ; and their author became a zealous Copernican. They served afterwards as a founda tion already prepared for the splendid superstructure of the Newtonian philosophy. They were framed out of materials gathered by Tycho. Hoene, in the Baltic, has thus played a conspicuous part in the world's history, looking to the causes of things. The castle of the heavens was not built in vain ! The phenomenon of a new star was again presented to the gaze of mankind in the year 1604, thirty-two years after the former appearance. It suddenly shone forth from the constellation of Serpentarius, continued visible upwards of a year, and gradually waned in its lustre before its final disappearance. When at the brightest it surpassed the fixed stars of the first magnitude and rivalled Venus, changed in colour from a yellow to a purple and fiery hue, and presented no sensible parallax. Keppler was one of its observers, and adopted the hypothesis that it proceeded from some vast combustion. But what these stellar apparitions portend is one of the mysteries of the universe. We may conjecture — we may theorise — but we cannot know. If they are bodies beyond tele scopic range, that start into temporary visibility under the action of fervent heat, their diminishing lustre and ultimate disappearance being the decline and termination of mighty conflagrations, " it is impossible," says Mrs. Somerville, " to imagine anything more tremendous than a conflagration that could be visible at such a distance." In 1607 the comet, afterwards known as Halley's, engaged the attention of Keppler, and again in 1618 he had the opportunity of observing a similar object. It is somewhat remarkable that he did not grasp the analogy between the orbits of these bodies and those of the planets. He attempted to determine the path of Halley's on the supposition of its motion being rectilinear, conceiving comets to be evanescent bodies, appearing and vanishing for ever. But he fulfilled a ministry in the great temple of nature sufficiently glorious as it is, and required not the anticipation of the triumphs of others to give him a hold upon the admiration of posterity. It is melancholy to reflect, that he lived in misery, owing ERA OF COPERNICUS, TYCHO BRAHE, KEPPLEU, AND GALILEO. 29 to the difficulty of obtaining his pension as mathematician to the emperor, through the rapacity of the subordinate officers of government, while the professional astrologers of the court, who flattered the vanity of the great, were magnificently recompensed. Sir Henry Wotton, the English ambassador, finding him in difficulties, invited him to this country ; but Keppler was too strongly attached to his native land to accept the proposal. He thus refers to it in one of his letters : — " The fires of civil war are raging in Ger many — they who are opposed to the honour of the empire are getting the upper hand. Shall I then cross the sea, whither Wotton invites me? I, a German — a lover of firm land — who dread the confinement of an island — who presage its dangers, and must drag along with me my little wife and flock of children?" At last the fatigue and vex ation of a fruitless journey to procure payment of his arrears terminated his life at Ratisbon, in the year 1630. The spot where he was buried — in the churchyard of St. Peter's — cannot now be identified; but a marble monument, consisting of his bust and the ellipse of Mars, the work of prince Charles of Alberg, has since been erected to his memory. The age of Keppler was the era of GALILEO, born at Pisa in 1564, whose discoveries made a profounder impression upon the public mind, and effected more for the system of Co pernicus, than those of his great compeer, because more open to popular comprehension, though not the fruits of so high an order of intellect. The early part of the seventeenth century was distinguished by the construction of an instrument which rendered objects accessible to human vision in the remoter depths of space, and which speedily added im portant accessions to the knoAvledge previously acquired of the visible heavens. A journey to Venice on the part of Galileo in the year 1609, the same year in which Keppler published his commentary on Mars — the accidental mention of a fact in a conversation there — led to the construction of the telescope, to the accurate survey of the heavens by it, and to the confirmation of those views of the universe which the retired ecclesiastic of Frauenberg had the sagacity to conceive and the boldness to adopt. Having heard that a Dutchman had contrived an instrument that magnified distant objects, the circumstance took possession of the mind of Galileo, and its important application in astronomy was imme diately perceived. He directed his inventive powers to the construction of such an instru ment for himself, and ultimately succeeded in perfecting a telescope which, in his own words, could " shoAV things almost a thousand times larger, and above thirty times nearer, to the naked eye." On examining the moon, he at once discovered its analogy with the earth, and detected the fallacy of the Aristotelian physics, which regarded all the celestial bodies as perfectly round, self-luminous, and without any terrestrial tarnish. The lunar surface exhibited plains and mountain ranges, highlands and glens, with the diversity of dark shadows and vivid illumination, which the face of our own globe displays as seen from some towering peak, or from the car of the aeronaut. But a richer harvest awaited him on turning his attention to the planets. Gazing at Jupiter on the night of January 7. 1610 — a memorable night — he saw three small bright stars eastward of the planet, and close to its disk. Subsequent observations revealed a fourth, and ultimately disclosed the fact that Jupiter was before him with a retinue of four satellites, which he named the Medicean stars, from his patrons the Medici. This was a death-blow to that dream of pride which the followers of Aristotle had been indulging for ages ; and one of the chief objections advanced by them to the Copernican doctrine was now demolished. The earth, as their vain philosophy had taught, could no longer be regarded as the most dignified body in the universe, having an attendant moon, and, on that ground, entitled to be the centre ; and, equally, she must resign her right to be at rest, for here was a more dignified body in motion. This revelation of the telescope was as gall and wormwood to the disciples of the ancient creed. They denied, for a time, the existence of the Medicean 30 HISTORY OF ASTRONOMICAL DISCOVERT. stars, but would not take the instrument in hand to look for themselves. " Oh, my beloved Keppler," wrote Galileo, "how I wish that we could have one long laugh together ! " In anagrams, the letters of which, when transposed, make the following sentences, he conveyed the result of the telescopic observation of Saturn and Venus : — Altissimum Planetam tergeminum obscrvari. The most distant planet I have observed to be threefold. Cynthiae figuras aemulatur mater amorum. Venus rivals the moon's phases. The practice was not then obsolete of publishing discoveries in philosophy in an ana gram, which could only be deciphered by the author, or by the party to whom he had conveyed the key. This was a relic, now happily extinct, of that pride of science prevalent in remote antiquity which disdained the communication of knowledge to the mass. The peculiar structure of Saturn, the subject of the first anagram, was only imperfectly discernible by the telescope of Galileo. The discovery of the phases of Venus, the subject of the second, was an important observation. It had been argued that, if the planet revolved round the sun, she ought to exhibit phases like the moon, whereas she always appears to the naked eye in full-orbed brightness. The argument was just and formidable ; and Copernicus could only reply to it, as tradition reports, that some time or other this resemblance to the moon would be found out. The prediction was verified seventy years after his death ; and, by the telescope discovering Venus exhibit ing the various phases of the waxing and the waning moon, the apparent objection to his system was converted into a confirmation of it by it being established beyond a doubt that the planet revolved round the sun. Another fact which the application of the telescope brought to light, illustrating the truth of the Copernican system, was the solar spots, their incessant motion, and the consequent rotation of the great luminary. The metaphysics of the schoolmen had taught the quiescence of the earth on account of its ponderous mass, but the position was destroyed at once by the sun, a far mightier body, being discovered to have a revolution upon his axis. Galileo was equally as successful in overthrowing the mechanical objections advanced against the doctrine of the earth's rotation, which supposed that the ground would pass away from beneath stones in the air and birds upon the wing. He showed that the atmosphere of the globe, and all bodies in it, will participate in the common motion of rotation, and illustrated his argument by referring to the clear case of a stone falling from the mast of a vessel participating in the motion of the ship. Galileo undoubtedly contributed more than any man of his age to weaken the hold which the natural philosophy of Aristotle had long had of the human mind, and establish a conviction in favour of the physical constitution of the universe as now demonstrated, though in early life he regarded the Copernican theory as a " solemn folly." But just in proportion to his success he became an object of malevolence to those whose pride would not submit to abandon opinions once embraced, however false, or whose ignorance could not appreciate the evidence of their falsity. The career of the Tuscan artist, as Milton calls him, turning to the moon his optic glass, At evening from the top of Fesole, Or in Valdarno, to descry new lands, Rivers, or mountains, in her spotty globe, was a splendid one, but its close was overcast with clouds and shadows. The authorities of the papal church were roused to treat his scientific demonstrations as heretical — to visit the illustrious observer with an ecclesiastical process on account of his opinions — and he had the mental and moral weakness to abjure what he knew to be true. Who ERA OF COPERNICUS, TYCHO BRAHE, KEPPLER, AND GALILEO. 31 can think of his mock recantation of the doctrines of the earth's axical and orbital motion without feelings of deep shame and regret ? — an old man, at the age of seventy, on his knees, with his right hand resting on the Gospels, renouncing opinions of the truth of which he had not the slightest doubt, and ecclesiastical authority exacting the sacrifice with the temporal sword. But in judging of the actions of men we should always take into account the circumstances of temptation in which they have been placed, the general current of opinion in their day, and a due sense of human infirmity. Such was the state of public feeling in Italy, that it is more than probable that Galileo regarded the service imposed upon him as a church ceremony, through which, as a son of the church, he was bound to go, without being responsible for its demerits. The sorrows that accompanied his descent to the grave, the indomitable energy which he displayed under them, together with his achievements, may be accepted as a reason for moderating censure upon his one failure in the time of trial. He lost his favourite daughter, Maria, in his old age — the charm and comfort of his life. The sight he had so well employed failed him, and he became totally blind. In sickness, his petition to repair to Florence for medical assistance was denied. He afterwards lost his hearing ; but his intellectual powers remained strong and active until his death in 1642, wanting a year to the birth of Newton, and to the lapse of a century from the death of Copernicus. Galileo was lax in his morals, like the rest of his countrymen, fond of society, of cheerful spirit, and highly popular manners. He was strongly attached to a country life, attended to agri culture, and spent much of his leisure among his vines. But for years he Avas a martyr to acute bodily pain. His house is still standing at Arcetri, about a mile from Florence, near St. Matthew's convent. His last surviving pupil, Viviani, became a fellow of our Royal Society, and lived to enter the eighteenth century. The remains of Galileo were interred in unconsecrated ground in the front of the noble church of Santa Croce in Florence. They have since been removed into the interior of the building, and laid in the centre aisle. His monument stands opposite the tombs of Dante, Alfieri, and Michael Angelo, and consists of a bust, said to be a portrait. A finger stolen from the coffin when the body was removed is now in the Laurentian Library, enclosed in a glass case, and placed in considerable state upon a pedestal. Galileo is thus apostrophised by the late American Minister in this country (Mr. Everett), in some lines written after visiting Santa Croce : — " And them, illustrious sage ! thine eye is clos'd, To which their secret paths new stars expos'd. Haply thy spirit in some higher sphere Soars with the motions which it measur'd here. Dost thou, whose keen perception pierc'd the cause Which gives the pendulum its mystic laws, Now trace each orb with telescopic eyes, And solve the eternal clock-work of the skies ? While thy worn frame enjoys its long repose, And Santa Croce heals Arcetri's woes." There is no reason to doubt the perfect sincerity of the theologians of the church of Rome in their proceedings against Galileo, and strong mitigating circumstances might be cited on their behalf. They believed his scientific conclusions to be contrary to the sense of Scripture, and hence acted under an honest conviction that they could not be true. Nor were they alone in this opinion, having the authority of all the early fathers on their side, and that of many Protestant interpreters. But as a book designed for popular use, the Bible is adapted for popular comprehension ; and hence its representations are framed in wise and benign accommodation to the understanding in ordinary life. The appear ance presented by physical nature to the eye of the observer is expressed, and not the 32 HISTORY OF ASTRONOMICAL DISCOVERY. philosophical fact — a style still in vogue, which shows its propriety, for we never speak of the globe rotating in common speech, but of the sun rising and setting ; and we are guilty of no false philosophy in popularly assigning fixidity to the earth, and speaking of its repose. Yet, overlooking the plain design and popular style of Scripture — rigidly con struing the latter — the theologians of the fifteenth and sixteenth centm-ies, in great numbers, regarded the sacred record as teaching the sun's daily apparent procession through the heavens, and the earth's stability, as physical facts, and hence denounced the Copernicans as heretics in religion, and deluded in philosophy. The controversy that ensued deserves attention, because, in a precisely similar way in our own times, the Scrip tures have been arrayed against geology. The termination of the former contest should have been a monitory example to some modern exponents of holy writ, not to assume their expositions to be right and the geologists wrong, but to admit the possibility of being fallible interpreters themselves. Before the death of Galileo the telescope had been adapted to instruments for mea suring angular distances. A countryman of our own, of the name of Gascoyne, who became a soldier in the civil war, and was slain while yet a youth in the battle of Marston Moor, is the first person recorded as having applied the telescope to the quadrant. This improvement in the art of observing perished with him, and was not known again in practice until a quarter of a century afterwards, when it appeared in France as a new invention. The same ingenious and unfortunate individual was the first constructor of the micrometer, by which the diameters of celestial objects are taken ; and this likewise remained unknown, to be re-discovered at the commencement of the eigh teenth century. Practical astronomy also received one of its most beautiful and important acquisitions soon after the telescope, in the application of the pendulum to clocks, afford ing a more exact method of measuring time. This was followed by the invention of the transit instrument, used in determining declination and right ascension, or the distances of the stars and any celestial phenomenon from certain fixed points in the heavens — a problem analogous to that of terrestrial latitude and longitude. The former was the work of Huygens, a Hollander, the latter of Roemer, a Dane — two invaluable contributions to the furniture of the observatory. But the " optic glass" of the " Tuscan artist " is the chief glory of the seventeenth century among mechanical constructions — as the germ of those mighty tubes which, at Greenwich, Dorpat, and Washington, now search the profun dities of space — utterly insignificant, indeed, when compared with them, as much so as the seedling to the tree which a thousand years has braved the breeze, yet still the germ ! A cylinder of lead, a few inches long, with two spectacle-glasses at its extremities, one convex, and the other concave — the plaything of a child — was the original tele scope ; yet, even in the day of its feebleness, it was sufficiently strong to break down the barrier which had arrested the knowledge of all antiquity, and manifest to the gaze of man what had successfully defied his glance for ages — the lunar steppes, highlands, and n.vines — Venus in phase — Jupiter surrounded with his servitors — and Saturn's strange and then inexplicable structure. ERA OF NEWTON, H ALLEY, AND HERSCHEL. is no great operation of which we are cognizant, by which Nature at a single bound perfects her marvellous productions. It is only by a combination of instruments operating generally through a series of years. The ultimate result is reached by a progressive advance, to which a number of artificers contribute. The cedar, on whose boughs the snow rests and the fowls nestle, is the work of centuries ; and the soil that laps its roots, the air that stirs its branches, the light that plays upon its crest, and the rain that drops upon its foliage, minister to the final development of the original cone. In like manner, the social and political changes that have improved the tone of society, elevated the condition of nations, and endowed them with an enduring liberty, have not been accomplished in the twinkling of an eye, or by individual intelligence and will. Popular history may embalm the name of some distinguished patriot or philanthropist, as having been the agent in rescuing a country from the yoke of arbitrary power, or breaking the bonds of personal slavery, and it may record a crisis of revolution confined within the limits of a year or a day ; but a comprehensive view of such occurrences will embrace a time of preparation, and crown with honour a variety of labourers, though to one may be due the glory of the sun, and to another the glory of the stars. The signa ture of the edict that dethroned the heathenism of the ancient civilised world occupied the imperial hand a moment's space, but the work of apostles, martyrs, and confessors, with the toils and sufferings of ages, are prominent in the picture. So the great demonstra tions and achievements of science have transpired by slow degrees, and yield a distinction to be divided among a fellowship of kindred spirits, rather than assigned exclusively to a solitary example of mental prowess. If Keppler discovered the general laws of the uni verse, the basis of the discovery was laid by Tycho ; and the marvellous Napier contri buted essentially to the issue obtained, by the invention of the logarithms, an admirable artifice, as it has been justly called, which, by reducing to a few days the labour of many months, doubles the life of the astronomer, and saves him the errors and disgust con- 34 HISTORY OF ASTRONOMICAL DISCOVERT. nccted with long calculations. If Newton developed the cause of those laws, he started to his grand result from a point expressly prepared by Keppler, and left the solution of the problem imperfect for Laplace to finish. It is obviously in wise accordance with the happiness of mankind, that no nation possesses a monopoly of talent and fame, that many of the most remarkable efforts of human genius owe a debt of obligation to the accom* plishments of genius at another era, and in a different clime. The fact proclaims the affinity of the species, between whom the mighty deep may roll, or the mountain rampart rise. It evinces too their mutual dependence, and will be hailed as a motive by the con siderate mind, to the maintenance of universal amity. We have seen four of the European nations represented in the advance of astronomical science — Poland by Copernicus, Denmark by Tycho, Germany by Keppler, and Italy by Galileo. The procession had been joined by Holland, France, and England, before the middle of the seventeenth century ; but it will be impracticable to record the labours, or even mention the names, of those who were then employed in the investigation of celestial phenomena. The selection of a few of the most distinguished is imperative. To Hevelius, one of the- merchant princes of Dantzic, an example of the close alliance of commerce with the fine arts and science which runs through the page of history, we owe the first accurate delineation of the lunar surface ; the discovery of a libration in longitude ; by his observation of the comet of 1664, he further corroborated the view pi'eviously taken, that such bodies are not sublunary, and approximated to the nature of their orbits. His contemporary Huygens, after effecting various improvements in the telescope, discovered one of the satellites of Saturn, the largest and best known, or Titan ; and obtained an insight into the singular structure of the planet, an inexplicable appearance to all pre ceding observers. An anagram, in the year 1656, announced to the world the following sentence by a transposition of letters, annulo cingitur, tenui, piano, nusquam coharente, ad eclipticam inclinato — the planet is surrounded with a ring, thin, plane, nowhere adhering, and inclined to the ecliptic. He justly observes, in a letter to his brother : " If any one shall gravely tell me that I have spent my time idly in a vain and fruitless inquiry, after what I can never become sure of; the answer is, that at this rate, he would put down all natural philosophy, as far as it concerns itself in searching into the nature of things. In such noble and sublime studies as these, it is a glory to arrive at proba bility, and the search itself rewards the pains. But besides the nobleness and pleasure of the studies, may we not be so bold as to say, they are no small help to the advancement of wisdom and morality 1" The discovery of the great nebula in Orion was accidentally made by Huygens in the year 1656. Cassini, nurtured in France, soon afterwards added four more satellites to the system of Saturn, those now called Tethys, Dione, Rhea, and Japetus, and he detected the black list, or dark elliptical line bisecting the surface of the ring, and dividing it into two. Astronomy is under immense obligations to a measure adopted by the courts of France and England at nearly the same period, for the patronage of scien tific associations, and the founding of national observatories. The Royal Society of London was incorporated by charter in the year 1662, and numbered among its early members Boyle, Hooke, WaUis, Ward, Newton, and Flamstead. The Royal Academy of Sciences at Paris was founded in the year 1666, and enrolled among its first members Auzout, Picard, Roberval, and Richer. Upon the invitation of Louis XIV. Huygens left Holland to become a royal academician, but being a Protestant, the revocation of the edict of Nantes ultimately compelled him to return to his native soil. The edict did not affect Cassini, a Catholic foreigner similarly invited ; and to him, with his son and grandson, the French academy owes much of its early distinction. Besides his before-named discoveries, he determined the periods of rotation of the principal planets, and observed the elliptical form of Jupiter's disc owing to compression at the poles. ERA OF NEWTON, IIALLEY, AND HERSCHEL. 35 Roemer, the inventor of the transit instrument with which he made observations from the window of his house, rendered no unimportant service by showing that the instru ments need not be fixed on high towers : he also discovered, in the year 1675, the interesting and hitherto unsuspected fact, of the progressive transmission of light through space, and the appreciable velocity with which it travels. This was attained by a series of careful observations of the eclipses of Jupiter's satellites. It was found, by comparing the times of immersion of the satellites in the planet's shadow and emersion from it, with the times calculated from the laws of their movements, that there was an acceleration or retardation of the phenomena by a few minutes, plainly dependent upon the variations of the earth's distance from Jupiter ; for the retardation was observed to be the greatest when the earth was in that part of its orbit most remote from him. The diameter of the orbit of the earth being a hundred and ninety millions of miles, we are more remote from Jupiter, by the whole of that distance, at one time than at another ; as, when the earth is in its orbit at a, its distance is greater from j than when at b by the interval between the two points. But notwithstanding this immense addition of space, or any conceivable increase, an eclipse would be observed to occur no later at the one than at the other, if light were propagated instantaneously. Eoemer found, however, a differ ence of eleven minutes to exist, which he afterwards estimated at fourteen, but which the precision of modern astronomy has fixed at sixteen minutes and a quarter. This deter mines the progressive motion of light, and the rate of its velocity. It requires time for its transmission ; and flying over the diameter of the earth's orbit in sixteen and a quarter minutes gives it a velocity of twelve millions of miles a minute, or upwards of a hundred and ninety thousand miles a second. Thus, in the eighth part of a second, it accom plishes the passage of a space equal to the equatorial circumference of our globe : yet so vast is the system to which we belong, that this swift-winged messenger, which requires no more than two hours to travel from the central sun to the farthest planet, could not dart through the intervening solitudes between us and the nearest of the stars under a period of five years. Notwithstanding the velocity of the rays of light, which travel more than fifteen hundred thousand times faster than a cannon ball, experi ment has not yet been able to detect that they have any impulsive power. The surmise has, however, been thrown out — and it is not improbable — that the attri tion of the solar beams with the terrestrial surface may have some connexion with the phenomena of heat. The national observatory of England — the noblest institution in the world for the extent and exactitude of its astronomical tables, and their practical value in the art of navigation — was originated by the spread of foreign commerce. The growth of our colo nies across the Atlantic, together with the establishment of our relations with India, ren dered it of the first importance to have an easy and accurate method of finding the longi tude at sea. A plan was proposed, founded upon the principle now in use, of observing the lunar motions and distances during a voyage, and comparing them with a previous home calculation, thus ascertaining the difference between home time and time at sea, from whence the difference of longitude is readily deduced. A reward being sought by the proposer from the government of Charles II., it was referred to a commission to report upon the merits of the scheme. Flamstead, one of the commissioners, at once decided against its practical utility, on the ground of the inaccuracy both of the lunar tables and of the positions of the stars in existing catalogues, which only a lengthened course of observation could rectify. The king, declaring that his pilots and sailors 36 HISTORY OF ASTRONOMICAL DISCOVERY. should not want such assistance, immediately instituted the office of astronomer royal, and determined upon founding an observatory. The site — selected by Wren — was a commanding eminence in Greenwich Park, in former times the seat of Duke Hum phrey's tower, within view of all vessels passing along the Thames ; a spot which Piazzi was accustomed to call the "paradise" for an observer; being free from a fluctuating atmo spheric refraction which annoyed him in the climate of Sicily. The foundation-stone was laid August 10th, 1675. An original inscription, still existing, states the design of the buildin"1 — the benefit of astronomy and navigation. The observatory has been succes sively under the superintendence of Flamstead, Halley, Bradley, Bliss, Maskelyne, Pond, and Airy, its present head, with assistants for its proper management. It is not a spot devoted to star-gazing, and the general observance of celestial phenomena, but essentially a place of business, carrying on by day and by night, when the weather permits, those ob servations of the sun, moon, planets, and principal stars, passing the meridian, from which the Nautical Almanac derives its information. This has been done with admirable regularity for a long series of years, nor has Europe any data comparable with the Greenwich tables. During the interval in which the office of astronomer royal is necessarily vacant, the business of the observatory proceeds; and that interval is now less than formerly. Thirty-three days elapsed between Bradley's last observation and Bliss's first; fifty-three between Bliss's last and Maskelyne's first; four between Mas- kelyne's last and Pond's first ; and two between Pond's last and Airy's first. It has been asserted by Baron Zach, that, if the other observatories had never ex isted, our astronomical tables would be equally perfect; and Delambre, when delivering an cloge on Maskelyne be fore the Institute of France, remarked, that if by some grand revolution in the moral or physical world, the whole of the monuments of existing science should be swept away, leaving only the Green wich observations and some methods of computation, it would be possible to re construct from these materials the entire edifice of modern astronomy. A few years ago it was resolved by the Lords of the Admiralty, that the time should be shown at Greenwich once in every day of the year. This is done by means of a large black ball which surmounts the north-western turret of the ob servatory. The ball, seen down in the vignette, is elevated by machinery to the index, showing the four cardinal points ; and, the instant it begins to descend, marks the mean solar time to be noon. Being plainly observable from the Thames, the arrangement affords a convenient opportunity for seamen to regulate their chronometers and clocks. The fame of FLAMSTEAD, the first astronomer royal, does not rest upon any brilliant discovery, but upon an enlightened view of the importance of accurate observation, and the unwearied zeal and industry with which he pursued it. A better representation of ERA OF NEWTON, HALLEY, AND HERSCHEL. 37 him cannot be given than by supposing Tycho Brahe in possession of a telescope, and the adaptation of it to other instruments. Laplace calls him " one of the greatest observers that has ever appeared," and Delambre remarks, " his name will be eternally cited like those of Hipparchus and Tycho, both of whom, as an observer, he surpassed." Born in the neighbourhood of Derby, and brought up in limited circumstances in that town, he wrought his way to a station at the head of practical astronomy, and established a con tinental reputation by dint of strong natural genius and unremitting application, in the face of great discouragements. Bad health was a frequent attendant upon him all his days. The patronage of the Crown did not screen him from the want of adequate resources, while from several of his scientific contemporaries he encountered dishonourable treat ment. The salary attached to his office, then a hundred a year, was often in arrears. Instruments were promised him by the government, but he had to find his own, com mencing his duties in 1676 with an iron sextant of seven feet radius, two clocks, and a quadrant of three feet radius, with two telescopes, which he brought with him from Derby. With these instruments he could only measure the relative positions of the stars, and it was not until 1689 that he succeeded in constructing at his own expense a mural arc to determine their absolute places. From this period, through an interval of thirty years, his time was spent in valuable labours, the fruit of which appears in the formation of a catalogue of three thousand stars, and a vast collection of lunar and planetary observations, from which Newton derived material assistance in forming his lunar theory. Yet, as if some annoyance must follow him to the grave, upon his death in 1719, the government of the day attempted to claim his instruments as public property, because found in the national observatory. The name of Flamstead, lost in a great measure to public recollection, or only dimly recognised as one of those who, with " lamp at midnight hour in some high lonely tower, may oft outwatch the Bear, With thrice great Hermes" — was revived a few years ago, and acquired notoriety at the expense of Newton and Halley's fame. It fell to the lot of Mr. Baily to discover a large number of his letters in private hands, with others, and a manuscript autobiography, upon the shelves of the library in the observatory ; and upon their publication, in 1835, by order of the Lords Commissioners of the Admiralty, some painful and unexpected disclosures were made. It may be admitted that Flamstead exaggerates his own case, that his temper was irascible, that he did not appreciate the value of Newton's theory, and over-estimated the importance of his own labours ; yet, after having allowed these elements of correction full force, the conclusion is sufficiently plain, that he was most injuriously treated, and that much of the moral distinction with which posterity has crowned the head of Newton is altogether misplaced. His deep obligations to Flamstead's lunar observations are acknowledged in the first edition of the Principia, but carefully suppressed in the second, apparently when irritated feeling had begun to operate ; and, in fact, nothing is more remarkable than the opinion universally entertained of the meek and placable disposition of the great philosopher, and the want of temper and honour displayed in his dealings with Flamstead. The truth appears to be, that as when we view a country beneath a brilliant sky and a balmy atmosphere, we are apt to frame our impressions of the people in harmony with the beauty of the scene ; so, to the early admirers of Newton, his intellectual greatness invested with fictitious lustre his private character, and the infirmities of the man were lost sight of in the glory of the sage. But however much we may take from the moral greatness usually attributed to Newton, and a considerable abatement is unquestionably necessary, his reputation for wonderful sagacity and grasp of mind is incapable of impeachment. The course of events has only 38 HISTORY OF ASTRONOMICAL DISCOVERY. served to render more conspicuous that sublime intelligence by which he unravelled the mechanism of the heavens ; and establish more indisputably his claim to be regarded as the architect of physical astronomy. To determine the motions of the heavenly bodies was the work of Keppler : to explain and demonstrate the causes of those motions was the achievement of Newton. So far however from gaining universal assent when first pro posed, his theory was ill understood, slightly appreciated, or altogether rejected by numbers of scientific men ; and, especially on the continent, it very slowly won its way to notice and confidence. Newton survived the publication of the Principia forty years, and at the time of his death, according to Voltaire, it had not twenty readers out of the country of its production. It was not until the mutual perturbations of the planets began to occupy the attention of the continental philosophers, that his theory was fully admitted abroad, and the work in which it was developed took the rank it has since occupied, pre-eminent, in the words of Laplace, above all the productions of the human mind. It is a common but vulgar error, to suppose the merit of our countryman to lie in conceiving the idea of the attraction of gravitation. That idea had been suggested to many minds long before his time, and the impression had been created that such a power in nature was the cause of the planetary motions. Thus Keppler surmised an attractive force to reside in the sun, producing these movements, and he even threw out the conjecture, that this force diminishes in proportion to the square of the distance of the body on which it was exerted. Borelli and Hooke also distinctly developed the influence of gravity, and both referred the orbits of the planets to the doctrine of attraction combining with their own proper motions to produce curvilinear movements. What really distinguished Newton, was not the idea of gravity as the principle of attachment between the different members of the solar system, but proving it to be so. He succeeded vague surmise upon the point with mathematical demonstration ; explained and applied the laws of the force ; an accomplishment which crowns him with honour above all his rivals, inasmuch as he who works a mine, and distributes its wealth through society, is incomparably in advance of him who has merely apprehended its existence, but failed in gaining access to its treasures. The manor-house of Woolsthorpe, a few miles from Grantham, seated in a little valley near the source of the Witham, was the scene of Newton's birth. Popular tradition reports, that the fall of an apple from a tree in the orchard belonging to this house was the mustard-seed out of which ultimately grew the grand theory of universal gravitation, and the story is not without a leaven of truth. It is certain that, to avoid the plague which ravaged England in 1666, Newton retired from Cambridge; and, when sitting alone in Newton's Birth-place. ^ garden at Woolsthorpe, his thoughts were directed to that remarkable power which causes all bodies to descend towards the centre of the earth. The supposition presented itself, that as this power extends to the highest altitudes of the earth's surface, it probably extends much farther into space ; so that even the moon may gravitate towards the earth, and be balanced in her orbit by the combined force of attraction and the centrifugal force implied in her motion. If this ERA OF NEWTON, HALLEY, AND HERSCHEL. 39 were true, the planets might be supposed to gravitate towards the sun, and to be restrained thereby from flying off under the action of the centrifugal force. Sixteen years rolled away before this beautiful hypothesis was verified, and difficulties arose in testing it which seemed to disprove it altogether. It was necessary to calculate the force of gravity at the surface of the earth ; to estimate its diminished energy at an increased distance ; and, after having found the law of the diminution, to ascertain whether the phenomena of the lunar motions corresponded proportionably with those of falling bodies at the terrestrial surface. Assuming the force of gravity to vary inversely as the square of the distance, it followed that, at the distance of the moon, it would be about 3600 times less than at the surface of the earth. The problem, therefore, to be solved was, whether the versed sine of an arc described by the moon, which measures the space through which in the same time she would fall to the earth, if abandoned to the action of gravity, would be 3600 times less than the space through which in the same time a heavy body falls, at the earth's surface, A B being the arc of the moon's orbit, c d the sine of the arc, and ef the versed sine. After a careful study of the lunar observations supplied by Flamstead, and a series of cal culations displaying unexampled originality and industry, New ton fully demonstrated that the versed sine of an arc described by the moon in one minute was equal to the space traversed in de scent by a heavy body at the surface of the earth in one second — the exact proportion that ought to exist, according to the mo dification to which the intensity of gravity is subject by variation of distance. The first certain gleam of this grand conclusion obtained by Newton, is said so to have overpowered him, that he Avas obliged to suspend his calculations, and call in the aid of a friend to finish the last few arithmetical computations. He saw the important relations of the demonstration — the planets wheeling round the sun — the satellites round the planets — the far-wandering comets returning to the source of light in obedience to the law of gravitation: — a result sufficient to throw the successful discoverer into nervous excitement. It is clear that, if a body be projected into space, it will proceed in the direction of the original impulse and with a uniform velocity for ever, supposing no obstacle to impede its course. But the combination of two antagonistic forces will produce a resulting motion in a diagonal direction. Suppose the straight lines A B to represent the direction in which the earth would travel under the influence of the projectile force which launched it into universal space : the straight lines A s are those it would describe at any point of its orbit if surrendered to the influence of the sun's attraction. The primitive impulse is, however, checked by the solar attraction, and the latter by the former ; so that while the earth, if abandoned to either, would describe A B or A s, the effect of their joint influence incessantly acting is to deflect it from both, and pro duce a curved path. The cause perpetually operating, the effect is constant ; and hence the formation of the terrestrial orbit, and the cause extending to the other bodies in the system, the planetary orbs are deflected from their natural rectilinear paths, and pursue a circuit round the common centre. The force of attraction is, however, proportional to the quantity of matter, and the proximity of the attracting body. Like light, the power of gravitation is weakened by diffusion, and diminishes as the square of the distance increases. This square is the product of a number multiplied by itself. A planet, therefore, twice our distance from the sun, will gravitate four times less than we do, the product of two multiplied by itself being four. Such is the great LAW OF 40 HISTORY OF ASTRONOMICAL DISCOVERT. GRAVITY, subject to the two conditions, that its force is directly as the mass of the bodies, and inversely as the square of the distance. It extends to the confines of the system, and acts as a mighty invisible chain to keep the primary bodies in brotherly relationship to each other, and in mutual subjection to the central luminary. And who can trace its operation without recognising a Supreme Potentate, who appointed to the sun his place, launched the planets in the depths, obedient to a law which has preserved the family compact originally established unbroken through the long series of ages ? It must, however, be borne in mind that the attraction between bodies is mutual, pro portioned to their masses and distances. While the sun attracts the planets towards himself, they also attract the sun, though their effect is comparatively small, owing to the vastuessof the solar mass. The planets likewise act upon each other ; and as their relative distances are perpetually varying, certain perturbations are caused in the system, which, though minute in each particular case, become considerable by accumulation, and yet are ultimately corrected and repaired by the same cause that produces them. Newton left to posterity the task of thoroughly investigating these inequalities, of showing them to be a result of the law of gravitation, and establishing the permanence of the system, notwith standing the accumulating influence of its internal disturbances. lie himself had no gleam of the latter truth, but seems to have entertained an opinion that the irregularities occasioned by the mutual action of the planets and comets would probably go on increasing till the system either wrought out its own destruction or received reparation from the direct intervention of its Creator. But Euler, Clairaut, D'Alembert, Lagrange, and Laplace have demonstrated the problem that the perturbations of the planets are periodic in their nature, that accurate compensation for them is laid up in store, so that the system is not arranged upon a principle of self-destruction. The elements of disorder and decay are removed from it. The very conditions of its existence guarantee its stability till the will of the great Ruler shall be expressed to the contrary. When an end shall come to its present constitution, that will not be the effect of its own faulty architecture, but of the fiat of OMNIPOTENCE. The house of Newton at Woolsthorpe, now the homestead of a farmer, has been in the ownership of persons anxious to protect it, and preserve every relic of its former oc cupant. Stukcley thus described it in 1727 : — "Tis built of stone, as is the way of the country hereabouts, and a reasonable good one. They led me up-stairs, and showed me Sir Isaac's study, where 1 suppose he studied when in the country in his younger days, or perhaps when he visited his mother from the university. I ob served the shelves were of his own making, being pieces of deal boxes which probably he sent his books and Room in which Newton was bora EUA OF NEWTON, IIALLEY, AND HERSCTJEL. 41 clothes down in on those occasions." Two sun-dials remain which he made when a boy ; but the styles of both are wanting, and one has been recently taken from the wall to be presented to the Royal Society. The room in which he was born has the following inscription upon a tablet of white marble : — " Sir Isaac Newton, son of John Newton, Lord of the Manor of Woolsthorpe, was born in this room on the 25th of December 1642." The apple-tree, the fall of one of the apples of which, according to tradition, drew his attention to the subject of gravity, was blown down by a gale some years ago, and a chair was constructed out of its timber. The Royal Society of London possesses his telescope ; the Royal Society of Edinburgh the door of his book-case ; and Trinity College, Cambridge, has a lock of his silver white hair. While the foundations of physical astronomy were laid by Newton, his confidant and friend, the brilliant and active Halley, pursued a remarkably successful career in the practical departments of the science. Born in mercantile life, yet independent of it through the wealth amassed by his father, he early embarked his means and energies in the advancement of observation. Leav ing Hevclius and Flamstead to keep guard over the northern hemisphere, he sailed to St. Helena to inspect the southern ; and in honour of the reigning monarch who patronised the expedition, the oak which had screened him from his pursuers after the battle of Worcester, was raised to a place in the skies, forming the constellation Robur Carolinum. The object of the voyage was to determine the absolute and relative positions of the stars invisible to the European eye ; but owing to the un- propitious climate of the island, only a ca talogue of 360 was made after more than a year's residence. Upon this voyage the oscillations of the pendulum were observed to decrease in number as the instrument approached the equator ; a fact noticed a few years previous by Richer, and ex plained by Newton to result from the greater intensity of centrifugal force there, proportionably diminishing the force of gravity. The life of Halley was v\^ '"$£$??%%' MSS^*. '"'"'(*%£ ^"' remarkable for locomotion, devoted to iiaiiey-s Tomb^ various scientific objects. He was twice at St. Helena, twice in the Adriatic, once in the West Indies, now with Newton in his study at Cambridge, anon with Hevelius in his observatory at Dantzic, and then with Cassini watching a comet at Paris. Upon the death of Flamstead, he succeeded to the office of astronomer royal, and though then in the sixty-fourth year of his age, he com menced the observation of the moon through a complete revolution of her nodes, involving a period of nineteen years, and lived to finish it, registering upwards of two thousand observed lunar places. It was while journeying in France towards the close of 1680, that he observed the great comet of that year, on its return from proximity to the sun ; 42 HISTORY OF ASTRONOMICAL DISCOVERY. and being aware of the conclusion of Newton, that such bodies describe very eccentric ellipses, his active mind began to study intently their phenomena, which resulted in a prophecy that has immortalised his name. After cataloguing and comparing a consider able number of comets, that of 1682 fortunately appeared. This he was led to regard as identical with those of 1456, 1531, and 1607, between which there is nearly the same interval. Hence he anticipated its return after the lapse of a similar period. " I dare venture," said he, "to foretell that it will return again in 1758 ;" and, sanguine as to the result, he called upon posterity to notice that it was an Englishman who had hazarded the statement. This was a prediction announced in 1705, the accomplishment of which ranks with the greatest achievements of modern astronomy, and will perpetuate the fame of Halley to the remotest generations. He had been gathered to his grave in Lee church yard seventeen years, when the celestial traveller re-appeared, at the time announced, to verify his words, illustrate his sagacity, and invest him with undying honour. Bradley, the English Hipparchus, the model of observers, as he is styled by Laplace, became the third astronomer royal upon the death of Halley. He had previously effected one of his two great discoveries, the aberration of the stars, an optical illusion, arising from the combined movement of the earth in space, and the progressive transmission of light ; a discovery of the highest importance, requiring the greatest precision of observation to detect. Ever since the doctrine of the earth's translation in space had been received, astronomers had been anxious to find some parallax of the fixed stars, as a sensible confirmation of the fact. Although the whole diameter of the earth's orbit is relatively insignificant, it is yet absolutely vast. Hence it was deemed no unreasonable expectation that some small apparent change of place in the heavens would be discerned in the case of the fixed stars, when viewed from the two extre mities of the earth's annual orbit, — separated from each other by the mighty chasm of a hundred and ninety millions of miles. To ascertain this, if possible, Bradley commenced observing a particular star, y Draconis, in connection with his friend the Hon. Mr. Molyneux, in the house of the latter on Kew Green, which was afterwards the residence of George III. The star in question was selected from its passing very near the zenith of their observatory. After a series of laborious observations, which began towards the close of the year 1 725, this star was found to have a southerly motion, a result which excited pro found surprise, as it was in a direction opposite to what would have been produced by an annual parallax. For instance, when the earth is in its orbit at A, the place projected in the heavens by the star B will be at c ; but when the earth is in its orbit at D, provided that there be any sensible parallax, the star will be seen in the direction E. Instead of this being the case, the observed appearance was that of the star appearing from D in the direction F. The observed change of place, then, could not be explained by means of parallax, or the earth's motion simply, because the change was in a direction opposite to what would have been caused by the parallactic motion. Suspecting some error, instruments were examined and observation renewed ; but the fact was verified, and the star was found to move southerly from December to April, then to move northerly again, returning to its original place in the December following, after having described a small apparent orbit in the heavens. The diagram represents the apparent course annually described by y Draconis, and other stars similarly situated. Imagine the line a bent overhead, z being a ERA OF NEWTON, 1IALLEY, AND HEKSCHEL. 43 the zenith, and p the pole. The ellipse represents the apparent movement of the star, the transverse diameter of which is about forty seconds ; and s its mean place. Aberration, or wandering, is the name given to this phenomenon. The term is not strictly accurate, as the apparent movements thus denominated are not irregular, but uniform. To discover the physical cause became an object of intense interest to Bradley, but it long baffled his researches and reasonings, and was at length developed by an acci dental circumstance. He was accompanying a pleasure-party in a sail on the river Thames. The boat in which they were was provided with a mast which had a vane on the top of it ; it blew a moderate wind, and the party sailed up and down the river for a con siderable time. Bradley remarked, that every time the boat put about, the vane at the top of the mast shifted a little, as if there had been a slight change in the direction of the wind. He observed this three or four times without speaking ; at last he mentioned it to the sailors, and expressed his surpi-ise that the wind should shift so regularly every time they put about. The sailors told him that the wind had not shifted, but that the apparent change was owing to the change in the direction of the boat, and assured him that the same thing invariably happened in all cases. From that moment he conjectured that all the phenomena of aberration he had observed, arose from the progressive motion of light com bined with the earth's motion in its orbit. This sagacious conjecture satisfactorily explains the apparent movement of the stars. Suppose a body to pass from A to B in the same time that a ray of light passes from c to B. Owing to the two motions, the impression of the ray of light meeting the eye of a spectator at B will be exactly similar to what it would have been if the eye had been at rest at B, and the molecule of light had come to it in the direction D, B. The star, therefore, whose real place is at c, will appear at D to the spectator at B. This effect is precisely analagous to what takes place when a person moves or travels rapidly through a shower of rain or snow in a perfectly calm state of the atmosphere. Without locomo tion the rain-drops or snow-flakes will fall upon his hat, or upon the head of the carriage that conveys him, and not beat in his face, or against the front windows of the carriage. But if he is passing along swiftly, in any direction, east, west, north, or south, the rain or snow will come in contact with his face, or enter the front windows of the carriage if they are open, as though the drops or flakes fell obliquely, and not from the zenith. Now as an object appears to us in the direction in which the rays of light strike the eye, it is easy to understand that a star in the zenith will appear at a little distance from it, to a spectator carried along with the earth in its orbit. This discovery established the fame of Bradley, who was exonerated from all future payments to the Royal Society on account of it ; and it is of great importance, as the only sensible evidence we have of the earth's annual motion. Soon after his appointment to the Greenwich observatory, he effected his second great discovery, that of the nutation of the earth's axis, a slight oscillation of the pole of the equator about its mean place, describing an ellipse in the period of eighteen years. He determined likewise its cause, which theory had previously inferred to be the action of the moon upon the equatorial regions of the earth. Some idea of his in dustry may be formed from the fact, that in conjunction with his nephew, he made no less than eighteen thousand observations in a single year while astronomer royal ; and the number from the year 1750 to 1762 amounted to upwards of sixty thousand. The death of Bradley was interpreted as a Divine judgment by the populace. He had taken an active part with the Earl of Macclesfield and others, in urging on and assimilating the British calendar to that of other nations. This rendered it necessary to throw eleven days out of the current year in the month of September 1752 — a measure which the ignorance of great numbers of the people led them to regard as an impious intermeddling with the 44 HISTORY OF ASTRONOMICAL DISCOVERY. Divine prerogative. Lord JMacclesfield's eldest son, at a contested election for Oxfordshire, was greeted with the cry from the mob, " Give us back the eleven days we have been robbed of ! " and Bradley's mortal sickness, some years later, was viewed as a punitive dispensation for having participated in the sacrilegious theft. The latter half of the eighteenth century furnishes a large catalogue of distinguished names, men of high scientific ability, and, for the most part, of the finest mathematical minds, by whose labours practical astronomy made vast advances, and the physical theory of the universe, as previously developed, was amply illustrated and confirmed. During this era lunar tables were constructed of sufficient accuracy to be employed to solve the great problem of the longitude at sea. This was the work of Mayer, for which his widow received the sum of 3000/. from our government ; and since that period, the pub lication of such tables, showing the places of the sun and moon, with the distance of the latter from certain fixed stars, for every three hours, three years in advance, has been a national object, contributing to the safety of navigators upon the trackless deep. The same period is also celebrated for the determination of the figure and magnitude of the earth, and for the great improvements made in instruments of observation. If the century opened with lustre derived from the physical demonstrations of Newton, it closed mag nificently with the telescopic discoveries of Herschcl, the wonderful resident by the stately battlements of Windsor, by whose mechanical skill and matchless industry new regions were added to our solar system, and views unfolded of the infinity of the firma ment, and the character of its architecture, which eye had not seen or the mind conceived. A work specially devoted to the life and labours of Herschel is a desideratum. It is not to the credit of the country, that the men who have headed its physical force upon the field of battle have enjoyed a larger measure of public admiration and gratitude, and found a more speedy chronicle, than those who have enlarged the field of thought, ministered to the intellectual gratification and elevated the mental character of the community. Bradley had lain in his grave 70 years, Newton 104, and Flamstead 116, before their memory received its meed of justice from the hands of Rigaud, Brcwster, and Baily ; a slackness to be attributed to the want of a due national estimate of the value of science, rather than to the reluctance of those who were competent to do ample honour to their merits. Herschel still remains without a record of this kind, though the materials for it are abundant, and his claims undoubted. Born at Hanover, the son of a musician in comparatively humble life, but early a resident in England, he appeared first as a professor and teacher of music, but rapidly rose by his own unaided efforts to eminence as an optician and astronomer. Anxious to inspect for himself the sublime revelations of the heavens, but destitute of means to purchase a telescope of sufficient power for his purpose, he resolved to employ some previous knowledge of optics and mechanics in the construction of an instrument. The earliest, a five-foot reflector, was completed in 1774 : but altogether he accomplished the construction of upwards of five hundred specula of various sizes, selecting the best of them for his telescopes. After having established his fame by the discovery of a new planet, and fixed his residence at Slough, under the munificent patronage of George the Third, he completed the giant in strument that attracted travellers from all parts to the spot, and rendered it one of the most remarkable sites of the civilised world. The tube was forty feet long, the speculum four feet in diameter, three inches and a half thick in every part, and weighing nearly two tons. Its space-penetrating power was estimated at 192, that is, it could search into the depths of the firmament 192 times further than the naked eye. We can form no adequate con ception of this extent, but only feebly approximate to it. Sirius, the brightest of the stars, is separated by a scarcely measurable gulf from us. But stars of a far inferior order of brightness are visible to the naked eye. These we may conclude to be bodies ERA OF NEWTON, IIALLEY, AND HERSCHEL. 45 far more remote, and reasonably suppose the star which presents the faintest pencil of light to the eye to be at least twice or thrice the distance of Sirius. Yet onwards, 192 times further, the space-penetrating power of the telescope at Slough swept the heavens. It was completed in the year 1789, but the frame of the instrument be coming decayed through exposure to the weather, it was taken down by Sir John Herschel in 1823. It will be convenient here to notice a reflecting telescope of far greater magnitude and power, recently constructed by the Earl of Rosse, and now in use at the seat of that nobleman, Birr Castle, in Ireland. The mechanical difficulties involved in this work — the patience, perseverance, and talent required to overcome them — and the great expen diture necessarily incurred — render the successful completion of this instrument one of the most extraordinary accomplishments of modern times ; and entitle its owner and projector, from first to last, to the admiration of his countrymen. When the mechanical skill and profound mathematical knowledge essential to produce such a work are duly considered, together with the years devoted to previous experimenting, and an outlay of upwards of twelve thousand pounds, this telescope must be regarded as one of the most remarkable and splendid offerings ever laid upon the altar of science. The speculum has a diameter of six feet, and therefore an area of reflecting surface nearly four times greater than that of the Herschelian, and its weight approaches to four tons. The casting — a work of no ordinary interest and difficulty — took place on the 13th of April, 1842, at nine in the evening ; and as the crucibles poured forth their glowing contents — a burning mass of fluid matter, hissing, heaving, and pitching — for the moment almost every one was anxious and fearful of accident or failure but Lord llosse, who was observed direct ing his men as collectedly as on one of the ordinary occurrences of life. The speculum has been formed into a telescope of fifty feet focal length, and is established between two walls of castellated architecture, against one of which the tube bears when in the meridian. It is no slight triumph of ingenuity, that this enormous instrument may be moved about and regulated by one man's arm with perfect ease and certainty. What will result from its application to the heavens remains to be ascertained, but an advancement of sidereal astronomy has already transpired. To return to Herschel. No addition had been made of any new body to the universe since Cassini discovered a fifth satellite in the train of Saturn. Nearly a century had elapsed without any farther progress of that kind. The solar system, including the planets, satel lites, and Ilalley's comet, consisted of eighteen bodies when Herschel turned his attention to astronomy •, but, before his career of observation terminated, he increased the number to twenty-seven, thus making the system half as large again as he found it, as to the number of its constituents — a brilliant recompense, but not an over-payment, considering the immense expenditure of time, and toil, and care. A primary planet with six moons, and two more satellites about Saturn, composed the reward. It was on the 13th of March, 1781, that, turning a telescope of high magnifying power — though not his gigantic instrument — to the constellation Gemini, he perceived a cluster of stars at the foot of Castor, and one in particular, which sensibly increased in diameter while the rest of the stars remained unaltered. Two nights afterwards its place was changed, which originated the idea of its being a cometary body ; an opinion embraced upon the continent when attention was called to it, but soon dispelled by clear evidence of its plane tary nature. The new planet was named after the reigning monarch by the discoverer, but received his own name from astronomers, which was finally exchanged for the Uranus of heathen mythology, the oldest of the gods, the fabled father of Saturn and the grandsire of Jupiter — referring to the position of the planet beyond the orbits of the bodies named after the latter. By this discovery the extent of the system was at once doubled ; for the 46 HISTORY OF ASTRONOMICAL DISCOVERY. path of the stranger lies as far beyond what had been deemed its extreme confine, as that limit is removed from the sun. The first moment of his " attack" upon Saturn, upon completing the forty-feet reflector, he saw a sixth satellite, and a seventh a month later, now called Mimas and Enceladus. But Herschel realised his most surprising results from the observation of the sidereal heavens. The resolution of nebula) and the Milky Way into an infinite number of stars — the discovery of new nebulas of various forms, from the light luminous cloud to the nebulous star — of double and multiple stars — of the smaller revolving round the greater in the binary systems ; — these were some of his reve lations to the world, as night after night, from dewy eve till break of dawn, he gauged the firmament. Caroline Herschel was the constant partner of her brother in his labo rious undertakings — submitting to the fatigues of night attendance — braving with him the inclemency of the weather — noting down his observations as they issued from his lips — and taking, as the best of all authorities reports, the rough manuscript to the cottage at the dawn of day, and producing a fair copy of the night's work on the ensuing morning. He died in 1822 ; but she survived to 1848, witnessing the heir of his name recognised as the heir also of his talents and fame. It was one of the conceptions of this remarkable man — as bold an idea as ever entered the human mind — that the whole solar system has a motion in space, and is advancing towards a point in the heavens near the star X Herculis. General opinion is now in favour of the idea, that not only the solar but the entire stellar universe revolves around some mighty centre. The nineteenth century commenced with a fresh ingathering of members into the planetary family. It had been deemed a matter of surprise that the immense interval of about 350 millions of miles between Mars and Jupiter should be void, when only spaces varying from 25 to 50 millions divide Mars, the Earth, and the inferior planets. Keppler had therefore started the conjecture that a planet would be discovered in the vast region between the two former bodies ; and thus bring it into something like proportion with the spaces between the latter. This idea was confirmed by a curious relation discovered by Professor Bode between the mean distances of the planets from the sun. It is to the effect, that proceeding outwardly from the sun, the interval between the orbits of any two planets is about twice as great as the inferior interval, and only half the superior one, except in the instance of Mars and Jupiter. Uranus had not been discovered when Bode arrived at tlu's remarkable analogy, but the distance of that planet being found to correspond with the law, furnished a striking confirmation of its truth. Write the Series, 0 3 G 12 21 48 96 192 Add to each term, 4444444 4 The sums are, ~4 7 10 16 28 52 100 196 If the third term 10 be taken to represent the distance of the earth, the third planet, in order from the sun, the remaining terms will represent very nearly the respective distances of the other planets. Thus, Mercury. Venus. Earth. Mars. — Jupiter. Saturn. Uranus. 4 7 10 16 28 52 100 196 The fifth term in the series is unrepresented, except by the exaggerated leap from Mars and Jupiter. It will be perceived, that while there is a striking approach to duple pro gression in the succession of distances, the condition is not exactly fulfilled ; and as it fails utterly in the case of Neptune, the last discovered planet, Bode's law, as it is called, is purely empirical The void in the series between Mars and Jupiter, so convinced the German astro nomers of the existence of a planet to occupy it, that a search for the concealed body was commenced. The anticipation was soon substantially realised by the discovery of ERA OP NEWTON, HALLEY, AND HERSCHEL 47 four planets — Ceres, Pallas, Juno, and Vesta, revolving round the sun at a mean distance of one hundred millions of miles from Mars, so small as only to be telescopic objects. This discovery we owe to Piazzi, Olbers, and Harding. Some singular features, without parallel in the planetary system, such as then: close contiguity, the intersection of their orbits, with their diminutive size, — Vesta not being much larger than the Spanish peninsula, — led to the surmise that these bodies are fragments of a planet which once revolved in their mean path with a magnitude proportionate to that of its neighbours. The possibility of such a disruption cannot be denied — the revolution of the fragments round the sun would follow in obedience to the mechanical laws by which the system is governed — but the point is obviously one of those questions which must remain entirely hypothetical. The career of planetary discovery which began with the century, was resumed in the year 1845 ; and has since been continued with most surprising results. Another miniature orb, Astreea, discovered by M. Hencke, was then added to the family of minute worlds rolling between Mars and Jupiter; and in one year alone, 1852, no less than eight such bodies were found. The known number at the time of writing these lines (1st of September 1857) is forty-five. Besides this, in the present age, the members of the solar universe have been increased by the detection of the primary planet Neptune, attended with a satellite ; and of an eighth satellite of Saturn, called Hyperion, remarkable for its simultaneous discovery by independent observers, in 1848, Mr Lassel of Liverpool, and Mr Bond of Cambridge, in the United States. The addition of a primary planet to our system demands a brief notice. Observations upon Uranus had shown the motions of that planet to present great irregularities, which could not be explained by the action of Jupiter and Saturn ; and after carefully examining the analytical theory of Uranus, Leverrier, a young academician of France, in the summer of 1846, published the elements of an undiscovered planet, the cause of the perturbations. He boldly predicted its existence, calculated its mass, and referred to its place in the heavens ; and scarcely a month afterwards, on the 23rd of September, the hitherto concealed object was found by M. Gallc of Berlin. But it has only been by accidental circumstances that France has the honour of this remarkable achievement. Upon retiring from the chair of the British Association, a fortnight before the observation of M. Galle, Sir John Herschel, in remarkable words, referred to the astronomical events of the past year, observing that it had given a new planet (Astrea) to our list, and adding, " it has done more, it has given us the probable prospect of the discovery of another. We see it as Columbus saw America from the shores of Spain. Its movements have been felt trembling along the far-reaching line of our analysis, with a certainty hardly inferior to that of ocular demonstration." This striking paragraph, as subsequently explained, had a twofold reference to the calculations of Leverrier, and to a similar investigation previously completed by Mr. Adams of Cambridge, the in dependence of the investigations, and their very nearly coincident results, justifying the confidence so strongly expressed by the speaker. Mr. Adams commenced his theoretical researches in January, 1843, recommenced them upon larger data in February, 1844, and obtained results for the heliocentric longitude, eccentricity of orbit, longitude of perihelion and mass of an assumed exterior planet, deduced entirely from unaccounted-for perturba tions of Uranus. These results were communicated to Mr. Challis, the Professor of Astronomy at Cambridge, in September, 1845. In October they were in the hands of Mr. Airy, the Astronomer Royal, whereas Leverrier's labours were not made public till the June of the year following. They were not then so complete as those of Mr. Adams, indicating merely the probable position of the hypothetical planet, while the latter had given values respecting its mass and the form of its orbit. The correspondence between two independent inquiries as to position inspired confidence, and Mr. Airy recommended 48 HISTORY OF ASTRONOMICAL DISCOVERT. a systematic search for the object, which Mr. Challis commenced on July 29. It now appears that, on August 4th and 12th, he actually seized the planet, and recorded two positions of it, but did not recognise it, through not comparing his observations, which a pressure of occupation, and an impression that the discovery required a much more ex tensive search, prevented. But for this, and the non-publication of the Cambridge mathe matician's results at the time they were forwarded to Mr. Airy, the honourable position of M. Leverrier would have been occupied by Mr. Adams, and that of M. Galle by Mr. Challis. The progress of astronomical discovery which has now been briefly traced, reminds us of the obligations we owe to those who have gone before us. How incumbent the duty upon us, then, as we have largely benefited by our predecessors, that, as faithful stewards of their gifts, we should hand them down to posterity with an increase of value ! How grand, and yet how simple, those views of the universe, upon the evidence of which we are now invited to gaze ! The Sun, a central orb, attended by a stately cortege of planets, forming a system under the empire of law, — a system not unique, but a general type of others as countless as the members of the stellar host, whose front ranks alone come within the range of tek'scopic vision ; — systems, probably, not physically insulated, but bound together by fine relationships, the nature of which; judging from the progress of the past, it is not arrogant to presume, will yet be revealed to the understanding of man ! These are not ingenious theories — splendid conjectures— hut established facts, and sober anticipations based upon them. To live and learn is the high vocation of humanity, one of the appointed ends which the great Artificer of existence contemplates in its continued scries; the generations that are to come improving upon the acquirements of that which now is. Nor can we fix any limit to the growth of knowledge in relation to the physical universe, clear and insurmountable in the present state as are its bounds with respect to the spiritual world. Who can descry a resting point in the wilderness of space ? — discern a barrier to the range of the creation ? Vast as are the regions that have been entered, there are vaster amplitudes unapproached beyond them, towards which the mind may advance in endless progression ; often indeed faltering in the pilgrimage beneath the burden of those conceptions of space and magnitude which immensity suggests, but still going onwards. THE SCENERY OE THE HEAVENS. CHAPTER I. THE SUN AXD SOLAU PHENOMENA. THE Sun — the central luminary of the sys tem — the source of light and heat — appears to prosecute daily a stately procession through the heavens, owing to the rotation of the I earth upon its axis, ascending like an in- I tensely brilliant ball from the eastern I horizon, and declining towards the west- | ern. Excepting the regions bordering on the poles, every part of our globe, within the interval of twenty-four hours, is brought beneath the action of the solar rays, and withdrawn from them — its " mountains and all hills, its fruit ful trees and all cedars." The unfail ing continuity and nice precision with which this has transpired, age after age, strikingly illustrate the stability of the natural laws. The navigator on a dangerous coast, watching for the morning, knows that the vision is for an appointed time, and !W>r™&G$&m&. 50 SCENERY OP THE HEAVENS. will infallibly keep the appointment. In countries favoured with a more transparent atmo sphere than our own, the day-spring, the commencement of terrestrial nature's diurnal audience with the solar presence, is a scene of great combined beauty and magni ficence. Faint rosy-coloured streamers are early indications of the point of sunrise; these rapidly become more distinct, and are followed by resplendent saffron hues, from that of burnished gold at the horizon, to the lighter shades gradually fading upwards into the pure cerulean of the illuminated sky. A recent pilgrim from the Western world to the sacred sites of the East, during his stay at Athens, went to witness the sunrise from the Acropolis, amid the solemn grandeur of its desolations. Seated within the ruins of the Parthenon, commanding a view of the horizon through the co lumns of the eastern portico, he awaited from the grey dawn the appearance of the orb of day. Gradually the sky became so resplendent in the direction of the advancing luminary, as to render it impossible to determine the precise point where his presence would be revealed. The tops of the northern mountains caught his beams, and some light fleecy clouds seemed changed into liquid gold, as, hovering over mount Ilymettus, they met the rays of the sun. At length, the eye encountered the solar glory, lighting up the columns and marbles of the Parthenon with a silvery splendour. It was one of those moments in the life of man, says Robinson, the traveller in question, that can never be forgotten. In our own latitude, the sunrise is a spectacle of surpassing interest and beauty, as viewed from the summit of Snowdon, or from some eminence overlooking the sea, in a propitious state of the atmosphere. The progressive illumination — the varie gated colours deepening and brightening that are pencilled on the sky — the growing distinctness of the superficies, whether field or flood — the retreat of mists and vapours glittering in the sunbeams while vanishing before their action; — combine to form a scene of visual beauty which has few parallels in the realms of nature. Light is sensibly transmitted to us while the sun is below the horizon. This is occa sioned by the refi-active and reflective properties of the atmosphere. By the former, the place of the luminary in the heavens is optically raised ; and morning and evening, when the lower limb appears to rest upon the horizon, the entire body is actually below it, and would be invisible but for the refraction of the rays. This effect is only produced while the depression is \vithin 33', which is rather more than the sun's greatest apparent diameter. At a further distance from the horizon, the rays pass over our heads into the upper regions of the atmosphere, and their direct transmission to the eye ceases. But they continue to reach us for an interval by reflection from the illuminated atmosphere, and produce the morning and evening twilight, the gradual transition from darkness to light, and from light to darkness. It is owing to the particles of air possessing the property of successively reflecting and re-reflecting the solar light, scattering it in every variety of direction, that all those objects are visible to us in the daytime, which are indirectly situated with reference to the luminary. Without it, the cloudless sky at noon, now so blue and brilliant, would present the blackness of darkness, with the exception of the places occupied by the sun and the stars. The latter would be as visible by day as at midnight, while no object would be perceptible, not receiving the direct sunbeams. It is not impossible but that at midnight, in the hour of the deepest gloom, some of the solar influence may be transmitted to us by an infinite number of reflections, so reduced, however, in its amount and power as to be imperceptible. The period of the sensible reflection of light from the sun, or the twilight, is generally supposed to be confined to his depression eighteen degrees below the horizon. The limit of depression, however, at which the greatest observed darkness commences, varies in different climates. In the torrid zone it has been found to be between sixteen and seventeen degrees ; and in France between seventeen and twenty-one. The duration of the twilight is different at every different latitude on the earth, and it varies in the same THE SUN AND SOLAR PHENOMENA. 51 latitude at different seasons of the year ; but much depends upon the atmosphere being free from clouds and fogs, or surcharged with them, as to its perceptible length in all places and at all times. Astronomically speaking, in the latitude of Greenwich, there is no night from the 22d of May to the 21st of July, but twilight from sunset to sunrise. It reaches its minimum three weeks after the autumnal equinox, and three weeks before the vernal equinox, having a duration of one hour and fifty minutes. At midwinter it is longer by rather more than a quarter of an hour than at the former periods, though this is not often perceptible, but rather the contrary, owing to the greater prevalence of clouds and mists at the winter solstice, intercepting, absorbing, and reflecting away from the earth the rays of light that otherwise would visit it. The duration is least at the equator and greatest at the poles ; but at the former there are two twilights every twenty-four hours, and at the latter only two in the year. At the north pole the sun is below the horizon for six months. But from the autumnal equinox to the 12th of November, and from the 29th of January to the vernal equinox, the solar depression is within eighteen degrees. Consequently through the whole of these intervals there is twilight, which reduces the extent of the absolute night to about two months and a half. If this region is thus for a long interval deprived of the solar presence, it is compensated by a lengthened possession of it at an opposite season of the year, for from the 20th of March to the 23d of September, the sun is constantly above the horizon. The annexed view exhibits the sun as seen at midnight at the North Cape of Europe, which is within Sun at Midnight at the North Cape. eighteen degrees of the pole — an appearance novel in the extreme to the dwellers in more southern latitudes. In the locality upon the earth's surface in which we are 52 SCENERY OF THE HEAVENS. situated, the frequent interchange of day and night, with the gradual advance and recession of both, is a benign and beautiful arrangement, the gentle, silent, yet emphatic signal of nature, for man to go forth to his work and to his labour until the evening, when the " ploughman homeward plods his weary way," to give sleep to his eyes and slumber to his eyelids. Owing to the refractive property of the atmosphere, the disk of the sun when near the horizon loses its circular form, and assumes an oval appearance. This is particularly observable when sunrise or sunset is viewed from the summit of a mountain, or from an eminence by the sea. The refringent power of the atmosphere being the greatest when nearest to the horizon, it follows that the rays of light proceeding from the lower limb of the sun are raised more than those which proceed from the upper point. This diminishes the apparent vertical diameter, while the apparent horizontal diameter is scarcely at all affected, as refraction acts only in a vertical direction. Measured by the micrometer, the vertical height of the solar surface, in the circumstances named, is sometimes found to be four, five, or even six minutes of a degree less than the horizontal width, and hence the term given to the appearance, that of the " horizontal sun." No such effect is perceived in other situations of the solar body, because refraction operates more feebly away from the horizon, and the difference between the refraction of the rays of light issuing from the upper and lower extremities of the vertical diameter is too small to be observed. "\Y~e are accustomed to speak of the meridian glory of the sun ; and independent of the greater purity of the atmosphere at noon, through the dissipation of mists and vapours, a greater quantity of rays reach the eye from the sun when high in heaven than when near the horizon. The air is an absorbent as well as a refractive and reflective medium : and however transparent the medium may be, the quantity of light absorbed will increase or diminish according to the extent of atmospheric space it has to traverse. This extent is much smaller with reference to an object in the zenith than one near the horizon. By a reference to the diagram, it will at once be seen that a ray of light passing from z the zenith will embrace a much less portion of the atmosphere included between the two arcs than one from n the horizon ; conse quently a less quantity will be absorbed ; and hence a ce lestial object will appear the brighter as its distance from the horizon increases. The comparatively dim and hazy appearance of objects seen in the direction of the horizon, is not only occasioned by the rays of light having to tra verse a larger space of the atmosphere, but of its lower strata, where it is the most dense and most absorbent. It is estimated that the solar light is diminished thirteen hundred times in passing through it, and we are thereby enabled to gaze upon the sun when setting without being dazzled by his beams. The apparent diameter of the grand orb varies slightly at different seasons of the year. This is owing to an actual variation of distance, for the ellipticity of the earth's orbit alternately increases and diminishes our proximity to the luminary. The solar diameter appears the least about the summer solstice, because the sun is then in apogee, or most remote from the earth. It is the greatest about the winter solstice, when the sun is in perigee, or at the nearest point to us. It' seems extraordinary at first sight, that at mid-winter, when the streams are ice-bound, the snow lies upon the fields, and the traveller shivers in the blast, we should be nearer to the sun than when, at an opposite season of the year, the greensward is burnt up, the cattle pant in the shade of the trees, and men seek a covert from the solar heat. But the effect of the sun's rays is increased or modified by two circumstances, more than sufficient to counterbalance that of the varying distance ; — the length of time during which they act continuously, and THE SUN AND SOLAR PHENOMENA. 53 their direction being more or less oblique. When he is farthest from us, as in summer, he is daily above the horizon twice as long as when he is nearest, at the winter solstice. This continued action causes a powerful accumulation of heat ; and the nights being short, but little of it is radiated, or given off, during his absence. But temperature is affected by the direction of the sun's rays, whether vertical or oblique, their greatest force being experienced when they are perpendicular to the surface ; while in proportion as they are oblique, they glance off, and having to pass through a larger portion of the atmosphere, a larger number are absorbed and dispersed by it. Out of ten thousand rays falling upon the earth's atmosphere, 8123 arrive at a given point if they come perpendicularly, 7024 if the angle of direction is fifty degrees, 2831 if it is seven degrees, and only 5 if the direction is horizontal. Now, in summer, the sun, being north of the equator, rises to a greater elevation in the heavens ; the rays reach us in a more vertical direction ; and the days being longer than the nights, more heat is absorbed than what is radiated. But in winter he traverses those signs of the zodiac that are south of the equator ; and, ascending to a less elevation in the heavens, the rays reach us more obliquely, and the days being short, the solar action is less continuous. Hence in summer we have the greatest heat though the earth is then farthest from the sun ; and in winter the greatest cold when it is at the nearest point. The mean distance of the sun from the earth, as determined by observation of the transits of Venus, is ninety-five millions of miles. This may be confidently regarded as within T^th of the true distance, so that no error is involved either way greater than about three hundred thousand miles. The immense magnitude of the solar body appears from the fact, that it occupies so much space in the heavens, and presents such a stately aspect, with so vast an interval between us. If a locomotive had been started five centuries and a half ago, at the termination of the Crusades, and had been travelling incessantly at the rate of twenty miles an hour, it would only now just have accomplished a space equal to that which lies between the terrestrial and the solar surface. Though light comes to the former from the latter in about eight minutes, a cannon ball would not perform the same feat, retaining its full force, under some twelve years. That an object therefore should be so splendidly visible as the sun, so far removed, and should so powerfully influence us with light and heat, argues grand dimensions and wonderful energy. The direct light is supposed to be equal to that of 5570 wax candles placed at the distance of one foot from an object ; and so great is the power of the rays, that some of the men employed in constructing the Plymouth Breakwater had their caps burnt in a diving-bell thirty feet under water, owing to their sitting under the focal point of the convex glasses in the upper part of the machine. The sun's diameter of 882,000 miles is equal to 111^ times that of the earth; and his circumference of 2,764,600 miles describes a bulk nearly a million and a quarter times larger than our own globe, and above five hundred times greater than the united volume of all the planetary bodies that revolve around him. If his mass occupied the place of the earth, it would fill up the entire orbit of the moon, and extend into space as far again as the path of that satellite. The density of the solar substance is, however, far less than that of the matter of our globe. If the two bodies could be weighed in a balance, the weight of the sun would not preponderate in the same proportion as the bulk, but be only 354,936 times heavier. This proportion is about a fourth less than that of the magnitude ; so that the same extent of solar substance would be found four times lighter than the same extent of terrestrial substance. To the naked eye the disk of the sun ordinarily presents a surface incomparably brilliant and uniformly luminous. There is no spot, or wrinkle, or blemish. The perfect purity of its aspect was an article of faith universally received by the ancient world. It 54 SCENERY OF THE HEAVENS. was not till telescopic views had been obtained, that the apparently smooth, unchequered, uniformly luminous face of the sun was found to be an illusion. The discovery of the vast and mysterious peculiarities, called the solar spots, is due to Galileo, though it has been claimed by and for other observers. They were first discerned by him in April, 1611. In a letter published in the following year, he announced their irregular and variable figures, the unequal term of their continuance, their motions across the disk in parallel lines, and their confinement to a narrow zone north and south of the sun's equator. Scheiner, a German Jesuit ; and Fabricius, the friend of Keppler, observed them about the same period, but not with the accuracy of Galileo. Being unacquainted with any method of intercepting a portion of the solar rays to save the eye, Fabricius could only observe the sun at the horizon, when his brilliancy was impaired by the density of the atmosphere, and even then he suffered much from the impression of the solar light. Our own countryman also, Harriot, the companion of Raleigh in his voyage to the New World, must be ranked among the first observers of these phenomena, the discovery and study of which have contributed to correct former opinions respecting the physical constitution of the great orb of day. Though ordinarily to the unassisted sight the sun exhibits a face of uniform and dazzling splendour, yet instances are recorded of his tarnished surface being perceptible to the naked eye. Herschel, who intently studied solar phenomena, and lost one of his eyes through the intense glare, mentions a spot appearing in the year 1779 large enough to be thus discerned. This may explain and justify some statements which have been regarded with incredulity. Thus, we have it upon the authority of Plutarch, that, in the first year of the reign of Augustus, the sun's light was so greatly diminished, that the unprotected eye might steadily contemplate his orb. Abulferagius also relates, that, in the ninth year of Justinian, the sun suffered a diminution of his light, which lasted above a year and two months ; and that, in the seventeenth year of the emperor Heraclius, half of his body was obscured, which continued from the first Tisrin till Haziran ; that is, from October to June. Keppler likewise states, that once in his time the solar aspect was strangely altered, as though a thick haze enveloped his body ; and the stars shone out at mid-day. Hakluyt gives the following entry from the log of a ship on the coast of Africa in December, 1590: — " The 7th, at sunset, we saw a great black spot on the sun ; and on the 8th, both at rising and setting, we saw the like, the spot appearing about the size of a shilling." The spots are all evanescent, but some arc sufficiently permanent to be recognised as the same after the lapse of a considerable period. They appear upon the eastern edge of the sun, and move towards the western, vanishing when its edge has been gained, reappearing at the eastern extremity in about thirteen days and a half, to pursue the same route. When first seen upon the eastern limb they scarcely seem in motion, afterwards they appear to travel slowly, their velocity increasing till the central regions have been passed, when they apparently relax, and gradually disappear at the western extremity. This is obviously an optical illusion occasioned by the oblique direction in which we view the marginal parts of the sun's body. The fact sensibly demonsti'ates the solar rotation ; but the period included between the appearance of a spot at the eastern edge and its return thither, is greater than the real time of one rotation, owing to the earth advancing all the while in its orbit. The apparent interval of revolution is rather more than twenty- seven days ; the true time of rotation is somewhat less than twenty-five days and a half, a much longer period than that taken by our own globe, harmonising with the mightier dimensions of the solar machine. The discovery of the chequered physiognomy and rotation of the sun was so repugnant to ancient ideas respecting the glorious orb, that upon Scheiner reporting the evidence of his senses to his provincial superior, the latter treated it as an illusion. " I have read," said he, " Aristotle's writings from end to end many THE SUN AND SOLAK PHENOMENA. 55 times, and I can assure you that I have nowhere found anything in them similar to what you mention. Go, my son, and tranquillise yourself ; be assured that what you take for spots in the sun are the faults of your glasses, or of your eyes." Scheiner was not allowed to publish his opinions under his own name ; and they appeared anonymously. Some general results of observation may now be succinctly stated. The spots are not uniformly obscure. They consist of a central portion, characterised by intense blackness, termed the nucleus, surrounded by a very distinct belt of a lighter shade, called the penumbra. The two portions do not gradually blend, but are separated by a well-defined boundary ; and this is true of the exterior part of the penumbra, which is in general sharply distinguished from the luminous region around it. By photometrical experiments, Herschel determined that representing the wholly luminous part of the solar surface by 1000, the relative brightness of the penumbra will be represented by 469, and that of the nucleus by 7. On some occasions, though rarely, a large nucleus has appeared without any penumbra ; and on the other hand, a penumbra without a nucleus has been seen. The spots are of very irregular shape, and varying magnitude. Sometimes they are numerous, but small, while individual spots appear of enormous dimensions. The latter are usually formed by simultaneous enlargement on all sides of the nucleus and penumbra from a comparatively minute speck. On the last day of June 1830, a spot of vast extent was observed. Its diameter was estimated at 23,000 miles ; and being nearly circular, its area included about 443,000,000 of square miles. But Mayer, in 1754, perceived a spot equal to ^th of the sun's apparent diameter, which gives it an absolute diameter of more than 45,000 miles. Still greater magnitudes are reported. Both in form and dimensions, the spots are subject to great changes, which transpire with astonishing rapidity. Two or more, situated very close together, will frequently expand towards each other, and form one large spot. On the contrary, one of great extent has been seen suddenly to crumble into" several smaller. Dr Wollaston observed a spot which seemed to burst in pieces, like a lump of ice thrown upon a hard surface. Herschel states, that on the 19th of February 1800, he fixed his attention on several spots ; but on looking off, even for a moment, they could not be found again. Sir John Lubbock also remarks, that he has observed spots visible to the naked eye, of which, on the following day, not a trace could be distinguished, even with the aid of a good telescope. These rapid and extraordinary changes indicate that the material subject to them cannot be solid, or liquid, but gaseous. It is a remarkable circumstance connected with the solar spots, that they invariably appear near the equator, but apart from it. By Galileo they were seen as far as 29° of latitude, north and south. But Scheiner found them extending to 30°, and called the intermediate region, on this account, the "royal zone." They have, however, been occasionally observed at a greater distance on both sides of the sun's equator, but never at 50 SCENERY OF THE HEAVENS. the circle itself, or within several degrees of it. They are thus confined to two belts of the solar surface, parallel to its equator, corresponding in some degree to the two temperate zones of the earth. Intervals of some length have occurred, during which the disk of the sun has been comparatively pure. This was the case from the year 1650 to 1670; and in 1724 the surface appeared unblemished. But from 1611 to 1629, according to Scheiner, it was never free from tarnish, except for a few days in December 1624. At a more recent date, scarcely a year has passed without spots being seen, many of which have been of great magnitude. It is supposed by Schwabe, whose observations have been continued without intermission for more than thirty years, that the extent of the solar surface obscured by spots increases and decreases periodically, the length of the period being eleven years and forty days. This remarkable conclusion has attracted great attention ; and upon the suggestion of Sir John Herschel, a photo-heliographic apparatus has lately been established at Kew, for the purpose of depicting the actual state of the solar disk from time to time. It has been thought, that spots of vast extent, or unusually numerous, may have the effect of depressing the terrestrial temperature, and thus affect the fertility of the seasons. But so far from such an inference being in harmony with observed facts, some of our warmest seasons have coincided with an accumulation of spots on the sun. Besides the dark spots, or maculce, as they are called, the telescope has disclosed other interesting appearances on the sun's disk. There are parts brighter than the rest of the surface — luminous aggregations — to which the term faculce (little torches) has been applied. They occasionally exhibit a round form, but have generally an extended, ridge-like shape. Though commonly seen in the immediate neighbourhood of spots, they sometimes appear alone, in which case they are almost always the precursors of spots, which become visible on the following day. Messier was frequently enabled by these brilliant indications to predict the appearance of spots twenty-four hours before they actually presented themselves on the disk. While the faculse are confined to the " royal zone," or region of the spots, the remainder of the solar surface is diversified with minute luminous specks and streaks, of varying brightness. These are bordered by more obscure parts, in which a multitude of small pores are observed, as black as the nuclei of the spots. The resulting mottled and corrugated aspect of the sun, Herschel compared to the roughness of an orange. Conjecture has been busy respecting the nature of these appearances, their cause, and probable indications respecting the physical constitution of the body to which they belong. The early observers, indulging the vagaries of imagination, supposed the spots to be the fuel of the solar furnace, or ashes floating on the surface of an abyss of combustion, or the smoke of volcanic explosions. But the views first broached by Dr Wilson of Glasgow, founded upon a minute examination of their peculiarities, substantially adopted and amplified by Herschel, now generally obtain with 'astronomers. It seems scarcely to admit of doubt, that the sun is a solid body, surrounded by two envelopes, suspended in a transparent atmosphere ; the upper one luminous, forming the visible surface ; the lower obscure, a layer of dense clouds, highly reflective, throwing back the light of the upper regions. In these strata, temporary openings or rents are supposed to be made by currents operating from below, analogous to the hurricanes and tornadoes of our tropical districts. The altered appearance of the spots, as they are carried round by the solar rotation, strikingly confirm the fact that they are excavations ; for after passing the centre of the disk, the penumbra is impaired on the side nearest to it, and gradually disappears ; then the nucleus is nipped on the same side, till it vanishes ; and then, finally, the penumbra on the opposite side begins to contract, narrows to a line, and is carried out of sight. These variations are exactly those which depressions will present in the course of rotation. Adopting this view, the nucleus of a spot is the exposed dense body or solid substance of THE SUN AND SOLAR PHENOMENA. 57 the sun ; the penumbra is the cloudy interior surrounding stratum ; and the faculae, or bright ridges, are accumulations of the exterior luminous matter, heaped up by the violent local agitations. In its interior physical constitution, therefore, that magnificent phantom, or globe of fire, which the ancients conceived the sun to be, is, in all probability, an opaque substance, like the ground we tread upon ; and, correspondingly, the atmosphere of our own globe is in a state of constant mutation. It is sometimes charged with clouds, which will completely hide the surface from view at no considerable distance from it. These are often rapidly rent asunder, gathered into distinct masses, and driven again into conjunction, affording transient glimpses of the earth to the adventurous aeronaut ; circumstances which are apparently analogous to the superficial solar changes, though comparatively upon a most puny scale. If this view of the constitution of the central globe be correct, there are strong resemblances between the sun and the bodies circulating in the system. They exhibit a family -likeness, being opaque masses, having a motion of rotation, and rotating in the same direction. In fact, according to Herschel, the sun appears to be nothing else than a veiy eminent, large, and lucid planet, evidently the first, or rather the only primary one of our system ; and because of this analogy, in regard to solidity, atmosphere, and diversified surface, he was led to infer that it is most probably inhabited by beings whose organs arc adapted to the peculiar circumstances of that vast globe. We feel it difficult to embrace this conclusion, from the fact of the solar rays producing, at the distance of so many millions of miles, a heat so considerable, that it must be intense and insufferable on the sun's surface, inferred to be far greater than that of the strongest blast furnace. But heat is only produced by the solar influence when it comes into contact with a substance that combines with it. Various experiments and familiar circumstances prove this to be the case. If the solar radiation collected in the focus of a powerful lens is thrown into the air, and continued there for a considerable time, no sensible heat will afterwards be perceived at the place, though had the most incombustible object been exposed there, such as gold or platina, it would have been fused. The eternal snow rests upon the summits of high mountains, which receive the direct influence of the sun's rays, while in sheltered parts of valleys below, receiving only their indirect influence, there is overpowering heat. The higher in the regions of the atmosphere an aeronaut ascends, the more intense is the cold, though there is nothing to interrupt the solar influence. Heat, therefore, is only generated by the sun's rays, when they unite with caloric, or heat in a latent state. We may conceive, then, the temperature of the sun's luminous atmosphere to be greater than that of any artificial heat which chemistry or galvanism can produce ; yet the great globe itself may be constituted incapable of any chemical combination with the rays of the brilliant atmosphere without, beyond a certain extent, and if so, a temperature consistent with animal and vegetable life may there exist. It is not, however, unlikely that the penumbra of the spots, — the stratum of dense clouds below the vividly resplendent visible surface of the sun, — may officiate to moderate the effect of the exterior atmosphere. Sir John Herschel, referring to that inner curtain of the mighty orb, remarks, " That the penumbral clouds are highly reflective, the fact of their visibility in such a situation can leave no doubt." They may thus serve the purpose of effectually defending the si-lar body from the insufferable light and heat of the outer most surface, furnishing the solid nucleus of the luminary with a moderate temperature by their friendly interposition. In the class of solar phenomena, Eclipses of the sun are always interesting, and sometimes imposing events. Few occurrences have given rise to more anxious feelings in the human breast, or have been watched with more unfailing curiosity. We are so familiar with their physical causes, and can predict with such nicety the time of their appearance, 58 SCENERY OF THE HEAVENS. that it is impossible for us to estimate the impression they would make upon the ignorant mind, transpiring under circumstances favourable to their full effect. To behold the sun, after shining in all its glory, apparently lose a part of the disk, become more indented, and then entirely invisible, while perhaps not a cloud has appeared upon the sky to account for the change of aspect ; to witness nature in the clear day suddenly invested with an unaccountable gloom, the larger stars becoming distinct, and the brute creation exhibiting symptoms of restlessness and alarm ; to feel a chilling cold supplanting the fervent heat of noontide, — these are peculiarities calculated to excite the consternation of uncivilised tribes, as well as of nations unacquainted with their true natural explanation. They have accordingly arrested the tide of battle, and perplexed monarchs with fear of change. In the first year of the Peloponnesian war, on a summer afternoon, there was an eclipse of the sun that was nearly total. Thucydides states, that the sun looked for a time like the crescent of the moon, and some stars appeared, but the full orb shone out afterwards in all its lustre. Pericles, according to Plutarch, was then on board his galley, about to proceed on a warlike expedition ; and it required some address on his part to quiet the apprehensions of his troops, who looked upon the darkness as an unfavourable omen. Not many years afterwards, when the Athenians were in desperate circumstances in the harbour of Syracuse, and had resolved on retiring, an eclipse of the moon happening at the hour appointed for the retreat, excited their alarms, caused a delay, and led to the destruction of both fleet and army. Columbus once rescued himself from circumstances of great difficulty, when in want of provisions which the Jamaicans refused to supply, by means of a lunar eclipse. Knowing that it was nigh at hand, he announced it to them as a token of the anger of the Great Spirit on account of their inhospitality, which had the desired effect when the beautiful orb began to be impaired. Chronology has derived much valuable assistance from the connection which superstitious fear has recorded between particular events and these phenomena, for eclipses may be calculated thousands of years backwards with the same precision as forwards. Thus the coincidence between a total eclipse of the sun, a rare occurrence in the same region, and the battle between the Lydians and Persians, establishes the date of the latter ; and the very day on which the great battle of Arbela was fought is likewise known from its taking place eleven days after an eclipse. A solar eclipse is occasioned by the dark body of the moon interposing between the sun and the earth, and deflecting a shadow upon the latter. The shadow cast by an object is merely an interception of the light of some illuminating body, and has its shape and extent determined by the form and relative magnitudes of the two. If the moon were as large as the sun, her shadow would be cylindrical, like the first figure, and of an unli mited length. If she were of greater magnitude it would resemble a truncated cone, the diameter and length in creasing to an indefinite extent, as in the second figure ; but being immensely inferior to the sun, she projects a shadow which converges to a point, like that in the third figure. This shadow, at the distance of the earth from the moon, can never be more than about a hundred and seventy miles broad ; and consequently the sun can never be totally eclipsed at the same instant over a greater extent of terrestrial space. But as the earth is continually moving, the shadow is a passing traveller, and sweeps over it ; no total obscuration of the sun lasting longer at one spot than about eight minutes. Although the limits within which an eclipse is total are very circumscribed, it will be more or less par tial over an area having a diameter of five thousand miles. In the diagram, lines o THE SUN AND SOLAR PHENOMENA. 59 drawn to the earth from the upper and lower limbs of the sun and moon define the conical shadow projected by the latter, or the umbra, which, wherever it falls, occasions a total ob scuration of the solar orb. Similar lines drawn to the earth along opposite edges of the two bodies define the limits of a fainter shadow, or the penumbra, caused by the moon only hiding parts of the sun's disk; and, within the space it includes, the eclipse is more or less partial, according to the situation of an observer. As a general rule, it may be stated that an eclipse will diminish in magnitude about one digit for every two hundred and fifty miles from the centre where it is total — a digit being the twelfth part of the solar or lunar surface. The lunar shadow may, however, terminate, when the earth is in a direct line with it, without reaching its surface. When the sun is at the least distance from us, and the moon at the greatest, the shadow will fall short of our globe by about twenty thousand miles, though when these elements are reversed it is sufficiently long to extend nearly the same distance beyond us. In the former case the sun has his greatest apparent diameter, and the moon her least. She is unable, therefore, to cover his entire face, and appears projected upon his disk, with a slender ring of dazzling light around her dark body. This is termed an annular eclipse, from the Latin, annulus, a ring. Annular Eclipse, An annular eclipse is a rare occurrence. The last, on the morning of October the 9th, 1847, was very imperfectly observed owing to cloudy weather. There may be five solar eclipses iu a year, and the least number which can take place is two. As the moon passes through that part of her orbit which lies between the sun and the earth once a month, we should obviously have an eclipse every month, every new moon, if she moved in the plane of the earth's orbit. This is, however, not the case — the lunar path is inclined to that of the earth. She is above it during one half of her course, and below it during the other, crossing it twice a month at two opposite points, called her nodes. It is only when the moon is between the sun and the earth, at or very near her node, that is, when her path cuts the plane of the earth's orbit, that she intercepts to us the solar light, and eclipses occur ; at other times, she passes either above or below the CO SCENERY OF THE HEAVENS. sun as seen from the earth, and the earth passes above or below her shadow. Owing to the irregularity of the moon's motions, she does not cross the plane of the earth's orbit at the same point in every revolution, but these points shift through a certain interval, after which the same change is repeated, and the same cycle of eclipses occurs. This interval is eighteen years and about eleven days, a period early discovered by the Chaldean astronomers, and used for the purpose of foretelling eclipses. Thus, on the sixth of May 1845, there was a solar eclipse ; and if we add to this era the ecliptic period just named, we are carried on to the seventeenth of May 1863, which will be the epoch of another. The complete period is 6585 days, 7 hours, 42^ minutes nearly. But though the eclipses of each cycle correspond, and may be regarded as identical wjth respect to the earth in general, they vary in then- appearances, and as to the localities in which they are visible. There was an eclipse of the sun visible at the north pole in the month of June 1295, but ever since, it has been proceeding more southerly. It made its first appearance in the north of Europe in August 1367. It was central in London in 1601, which was its nineteenth return; and nearly so again on the 15th of May 1836, its thirty-second appearance. At its thirty-ninth return, in August 1880, the lunar shadow will fall south of the equator, and continue receding from it, until its seventy-eighth appearance will be at the south pole, on the 30th September 2665. Though solar eclipses are of common occurrence, yet a total one depends upon a con junction of so many circumstances, that the spectacle happens only on very rare occasions, even anywhere on the surface of the earth. Especially at the same place, or within convenient distance of it are the opportunities for observing the phenomenon few and far between, so that entire astronomical lives have passed away without being gratified with the sight. Halley, in a paper on the total eclipse of the sun which happened at London on the 3d of May 1715 — the reign of George I. — remarked, that there had not previously occurred a similar event, visible in that city, since the 20th of March 1140 — the reign of Stephen — an interval of five hundred and seventy-five years. " I forbear," he observed, addressing the Royal Society, "to mention the chill and damp which attended the darkness of this eclipse, of which most spectators were sensible and equally judges. Nor shall I trouble you with the concern that appeared in all sorts of animals, birds, beasts, and fishes, upon the extinction of the sun, since ourselves could not behold it without some sense of horror." One of his correspondents who was stationed on an eminence on Salisbury Plain, wrote to him as follows : " It was the most awful sight that I had ever beheld in my life. We looked in vain for the town of Amesburg, situated below us ; scarcely could we see the ground under our feet. So deep an impression has this spectacle made on my mind, that I shall long be able to recount all the circumstances of it with as much precision as now." The total obscuration lasted 3 minutes, 22 seconds. The planets, Jupiter, Mercury, and Venus, with the stars, Aldebaran and Capella, were visible to the naked eye. A partial solar eclipse, however considerable, gives not the faintest idea of what a total one is, as to the obscuration, the chill, and the altered physiognomy of heaven and earth. The " Saxon Chronicle" records of the eclipse in the reign of Stephen : — " In the Lent the sun and the day darkened about the noontide of the day, when men were eating ; and they lighted candles to eat by. Men were very much struck with wonder." Of the same event, William of Malmsbury states, that " while persons were sitting at their meals, the darkness became so great, that they feared the ancient chaos was about to return, and upon going out immediately, they perceived several stars about the sun." An eclipse visible in Scotland in 1433, was long remembered by the people of that country as the Black Hour; another in 1598 was similarly commemorated by the inhabitants of the border counties as the Black Saturday; and a third in 1652 gave rise to the expression THE SUN AND SOLAR PHENOMENA. 61 of Mirk Monday. The darkness which attends full solar eclipses appears to vary, owing chiefly to a difference in the condition of the atmosphere, and the time of the day. Though strongly marked on all occasions, it is more peculiar than profound ; and altogether confined to the brief period of totality. So long as the smallest portion of the lustrous orb is visible, there is considerable light. Nature simply looks sobered and saddened till the moment of entire obscuration arrives. Then, besides the sensible diminution of light, a strange, spectre-like aspect is stamped upon the appearance of every object — sky, clouds, trees, buildings, mountains, streams, animals, and man — producing an effect which is unexpected, sublime, and even appalling. Equally startling and remarkable is the change upon the first re-appearance of the solar ray. It rushes out suddenly, and with brilliant effect from the limb of the overshadowed orb, and in an instant the day is restored to nature. An interesting anecdote appeared in the journal of the Lower Alps respecting the eclipse of July 8, 1842. "A poor child of the commune of Sieyes was watching her flock when it commenced. Entirely ignorant of the event which was approaching, she saw with anxiety the sun darken by degrees, for there was no cloud or vapour visible which might account for the phenomenon. When the light disappeared at once, she began to weep ; and in the height of her terror, called out for help. Her tears were still flowing when the sun sent forth his first ray. Reassured by the aspect, the child crossed her hands, exclaiming, in the patois of the province, "0 beou soideou!" "0 beautiful sun!" The eclipse just referred to excited extraordinary interest, as the lunar shadow travelled over a part of Europe studded with crowded cities, the north of Italy, and the southern provinces of France, Germany, and Russia. It was well observed at various stations by the leading astronomers of the age. M. Arago awaited its occurrence at Perpignan ; M. Valz at Marseilles ; M. Petit at Montpelier ; M. Carlini at Milan ; MM. Santini and Conti at Padua ; MM. Schumacher and Littrow at Vienna ; MM. Otto Struve and Schidlowsky at Lipesk ; while of our own countrymen, Mr Baily was posted at Pavia, and Mr Airy at the Superga near Turin. The sun was totally hidden 2 m. and 11 s. at Perpignan ; and 3 m. 5 s. at Lipesk. The planet Mare, with Aldebaran, Capella, two stars of the constellation Gemini, and others, shone out. At Venice, the citizens remarked, with reference to a steamer on the Lagunes, that the column of smoke from the funnel ceased to be visible, while the sparks of fire which accompanied it were very distinct and striking. The obscurity had a wan and livid hue — a shade of grayish olive — which seemed to throw over nature an air of appalling sickliness, and imparted to the human countenance an aspect painful to contemplate. The heavens appeared of a grayish violet ; horses and other animals employed in the fields halted at once, and obstinately refused to move ; but, on the other hand, the fact was well ascertained, that horses in the diligences jogged on without seeming to be at all affected by the phenomenon. At Montpelier, the bats, thinking that night was come, left their retreats ; an owl was seen to leave the church tower of St Peter, and fly over part of the town ; the swallows disappeared ; the fowls went to roost ; a herd of cattle, feeding in a field, formed themselves into a circle, with their heads directed outwards, as if to resist an attack ; and several plants, which usually shut up their leaves at night, were observed to close. A heavy dew fell at Perpignan, Turin, and Vienna, during the total obscuration ; and the red stars Aldebaran and a Orionis appeared quite ivhite. The fidelity with which this eclipse answered to previous calcula tions respecting the time of its occurrence, made a powerful impression upon the popular mind, with reference to the advanced state of science, and the regularity which marks the great clock-work of the universe. At Milan and Pavia the populace gave vent to their feelings in a general Huzza.li! vivent les astronomes f When totally obscured by the body of the moon, the place of the sun is made apparent by the brightness of that part of the heavens in which it is situated. This brightness appears 62 SCENERY OF THE HEAVENS. in the form of a corona, or luminous ring, encircling the moon and exhibiting a radiating .aspect. The most probable con clusion, founded upon its round shape, nebulous structure, and gradually diminishing density out wards, is, that the ring is due to the presence of an extensive atmo sphere which encompasses the solar orb. Other striking features of total eclipses are ruddy sj)ots, or pro tuberances, varying in colour from I light pink to deep crimson, which appear upon the margin of the dark lunar disk. They have been com pared by different observers to beautiful sheaves of flame, and to the snowy peaks of the Alps, rose- I coloured by the morning or evening sun. These appearances are supposed to arise from clouds suspended in the atmosphere of the sun, which absorb nearly all the rays of the spectrum, except the red, as in the case of the terrestrial clouds when illuminated after sunset. It has been often remarked, that when the margin of the moon comes into contact with that of the sun, the appearance pre sented is that of a broken glimmer of light, which the late Mr Baily compared to a link of bright beads. The curious spectacle of " Baily's beads," as they are called, seems to be caused by the rough mountainous edges of the moon, which touch the margin of the sun, while transiently the sunlight gleams through the chinks or valleys between them. A delicately luminous cone is sometimes seen accompanying the sun, extending from the horizon obliquely upwards in the direction of the zodiac, and, therefore, called the Zodiacal Light. It appears before sunrise and after sunset, but is never seen by us so well denned as in the equatorial regions, though it may frequently be discerned after the evening twilight in March and April, and before the morning twilight in September and October. The light resembles in appearance the tail of a comet. The faintest stars shine through it. Its colour varies according to the state of the atmosphere, but it is generally of a pure rose tint. The bright ness also varies, and some years it has never been seen at alL Keppler appears to have been the first who noticed this phenome non. Afterwards Cassini observed it, and when Humboldt was tra velling in South America, he had several distinct views of it at Ca- raccas. Its extent from the sun, Zodiacal Ught. situated at its base to the vertex, varies from 45' to 50', and its breadth at the base from 20' to 30'. It has been conjectured that MEECI7EY — VENTTS — THE EARTH. 63 it derives its form, — that of a long and narrow ellipsis, only the half of which we see, — from its rapid revolution with the sun on its axis; but the nature of the pheno menon itself is one of those points respecting which we are compelled to confess our ignorance. The decline of the sun to the horizon is as imposing a spectacle as his advance to it, when the atmosphere favours the exhibition of the descent. The most gorgeous sunsets are those of the West Indies, during the rainy season. The sky is then sublimely mantled with gigantic masses of clouds, which arc tinged with the glare of the descending luminary, and which seem to be impatiently waiting for his departure in order to discharge their pent-up wrath on the bosom of the night. In the South Atlantic the sunset has a milder and more sober aspect. In the Eastern tropics it has generally an overpowering fierceness, as though the last expression of the solar heat should be the greatest. But during the summer, in temperate latitudes, there is often a serenely beautiful horizon, a mellowness of light, together with a rich and varied colouring of the sky, which combine to render the European sunsets far more attractive than those which are intertropical. The milder radiance of the " great light" in parting from us presents a picture to the eye of the sentiment of the All-Merciful, " Again, a little while and ye shall see me." And how open to observation are wise Contrivance and bountiful Design in the unvarying position of the sun in the centre of the system, and the axical rotation of his tributaries, which not only guarantee the regular return of their surfaces to his presence, but the undiminished power and splendour of his beams ! If, instead of an instant creation, we suppose the masses of the sun and of the planets to have been gradually formed, under control of the law of attraction, the question still arises, how it came to pass, that the self-luminous matter was collected into one mass at the centre, and not gathered into many masses like the matter of the planets. So striking did this circumstance appear to Newton, that he remarked in his first letter to Bentley : " I do not think it explicable by mere natural causes, but am forced to ascribe it to the counsel and contrivance of a Voluntary Agent." CHAPTER II. MERCURY — VENUS — THE EARTH. To a superficial observer of the heavens at night when the moon is absent, only one class of objects will be apparent — the stars. But a little attentive observation will discover other bodies, which, besides taking part in the apparent revolution of the celestial concave, will be found to have independent movements. They seem stationary at intervals, then in motion from west to cast, and going back again from east to west, their positions con stantly changing in regard to the earth, to each other, and to the host of stars. These peculiarities were marked in very early times, and in allusion to them the Greeks applied to such bodies the term planet, which signifies to wander. Their course, capricious and uncertain to the ancient eye, is now discerned to be a direct and regular highway ; and hence, if as yet they had received no general title, we should find one for them, expressing the prosecution of orderly rather than erratic travel. The planets are divided into primary and secondary. The former revolve round the common centre of gravity in the system ; the latter officiate as satellites to the primaries in their great pilgrimage, and combine with it a revolution round them. The planets are also divided into inferior and superior, referring to their positions being within or without the path of the earth. The expressions are somewhat unfortunate, for the immediate idea conveyed by them refers to 64 SCENERY OF THE HEAVENS. magnitude rather than to situation, and in that sense is erroneous. Venus, an inferior planet, is far larger than Mars, one of the superior, and more resplendent than any of the rest. The words interior and exterior will exactly express what is intended, prevent confusion, and had better be adopted. The planets are denoted in astronomical writings by then: respective symbols, as § Mercury, $ Venus, (B the Earth, $ Mars, 2£ Jupiter, \l Saturn, ^ Uranus, and ¥ Neptune. The paths of the planets are elliptical, as previously described ; but the ellipses vary to some extent in their eccentricity, or as to the distance of the sun at s, from the centre of the oval, which here represents a planetary orbit. This distance in the case of Mercury is about seven millions of miles ; in that of Venus it is less than half a million ; in that of the Earth it is somewhat more than a million and a half; in that of Mars it is upwards of thirteen millions ; while in that of Juno and Pallas it is sixty-four millions and a half. The orbits of the planets are more or less inclined to each other, instead of lying in the same plane. It may be desirable here to explain the meaning of this oft-recurring phrase. Referring to the earth, an imaginary smooth and thin surface, cutting through the centre of the sun, and reaching out to the fixed stars, is the plane in which the earth moves in revolution round * * » * *. **_«v***__^ 7»,v.-»* * " .** •*.*.* the sun. This is represented by the shaded part of the diagram. The stars to which it extends form the constellations of the zodiac, the circle A, B, C, D, being the ecliptic, which shows the sun's place in the heavens as seen from the earth, or the earth's as seen from the sun. The orbits of the other planets are in different degrees inclined to this plane, one half being below and the other half above it. If we suppose the shaded part of the diagram to be the surface of a basin of water, a ring held inclined so as to dip into it half way, will describe the relation between the plane of the earth's orbit and that of another planet. The mean velocity of the planets in their orbits exhibits great diversity, those which are nearer to the sun being far more rapid than those which are remote. Saturn prosecutes his circuit at the sober pace of little more than twenty thousand miles an hour, while Mercury rushes on at a rate which is more than five times that speed. The extraordinary swiftness of the interior planets is obviously necessary to counterbalance the powerful attraction of the solar mass, which acts with diminished force upon the bodies that are more distant from him. MKRCURT, the nearest planet to the sun, is the smallest primary in the system, with the exception of the asteroids. It is the fastest traveller also, having a velocity in space which is nearly twice the rate of the earth's orbital motion. It is the densest celestial body with which we are acquainted, supposed to be fourteen times that of water. A globe of lead therefore of the same volume, if weighed in the balances against its mass, would be found wanting. Yet notwithstanding this remarkable density, if loosened from the centrifugal force, it would require more than a fortnight for the planet to accomplish its dash headlong to the sun. The days and nights are about the same length as our own ; but a whole cycle of seasons has been four times gone through, before the earth's MERCURY VENUS — THE EARTH. 65 spring, summer, autumn, and winter have once revolved. Owing to comparatively near neighbourhood, the sun will occupy seven times more space in the Mercurian heavens than in ours, and afford a light and heat which would be intolerable to our organs without some modifying circumstances. We may, however, dismiss the idea of water always boiling at the surface, and an ever-burning heat seven times greater than the fiercest experienced at our equator, distinguishing its material. The sensible heat at the different planets may depend chiefly upon their substance being more or less adapted to combine with the solar influence ; there is nothing improbable, therefore, in the supposition that the nearest may be as cool, and the remotest as warm, as the temperate zones of the earth. Besides, it is a proud presumption to imagine the organism of the terrestrials to be the standard and model of finite beings. We are bound to admit that the great Author of existence can as duly attemper to every dwelling-place the physical constitution of its inhabitants, as obtains with reference to our globe and its population. Mercury is at the mean distance of thirty-seven millions of miles from the sun, and performs an orbital revolution in about 88 days, travelling at the rate of more than a hundred thousand miles an hour. This speed originated the name — that of the swift- winged messenger of the gods. The planet rotates upon its axis in rather more than twenty-four hours, and has a diameter of 2950 miles. Its volume must therefore be increased upwards of twenty millions of times in order to equal the sun in magnitude ; but the mass, if increased only two millions of times with matter of the same density, would be equal in weight. Mercury is an evening star when eastward of the sun, and a morning star when westward of him, but is quite invisible to the naked eye, owing to the vicinity of the solar splendour, except at or near the time of the greatest elongations. The telescope discovers phases like the moon, and atmospheric indications. Some have even professed to discern irregularities of outline, supposed to express superficial elevations ; but of this we have no certainty. Not the least departure from the circular form in the shape of the planet was detected till the transit of November 1848, when micrometrical measurements, executed by the Eev. Mr Dawes, showed it to be slightly spheroidal. Astronomers have been sorely plagued in their observation of Mercury — a giddy planet — imperceptible generally, through a close attendance upon the sun — never at such a distance from him as to appear in a dark part of the heavens — and going at a rate through space, which is a perfect gallop when compared with the sober jog-trot of the earth. These circumstances, together with the smallness of the planet's mass, and a peculiar quick scintillation, render it a very difficult object to examine. Copernicus is said never to have seen Mercury through his whole life, and Delambre was only able to discern him twice with the naked eye. The description of one of the old writers — a "squirting lacquey of the sun, who seldom shows his head in these parts, as if he were in debt" — however odd, is yet characteristic. The planet may be caught for a short time before sunrise in autumn, and after sunset in spring ; and appears to shine with a brilliant white light, being alternately a crescent, a semicircle, and gibbous. When between us and the sun, and at the same time in the plane of the earth's orbit, Mercury transits the solar disk, and is seen as a small black speck 66 BCENEKY OF THE HEAVENS. upon the surface, an evident proof of the borrowed radiance of the orb. The first transit ever observed was predicted by Keppler, and witnessed by Gassendi, at Paris, on the 7th of November 1631. The second observed transit, on the 3d November 1651, was watched at Surat in India, by Shakerley, a young Englishman, who, having found by calculation that it would be visible only in Asia, proceeded thither to witness the occurrence. The third recorded transit, on the 3d of May 1661, was observed by Hevelius at Dantzic, and bv Huyghens, Street, and Mercator at London, who are said to have made their observa tions at Long Acre, with a telescope of excellent workmanship. Halley enjoyed the sight of another 7th November 1677, at St. Helena; and was the first who witnessed both the ingress and egress of the planet. Lalande, in his old age, remarked of the transit of 8th November 1802 : — "The passage of Mercury over the sun's disk was observed this morning for the nineteenth time. Astronomers enjoyed in the cornpletest manner the sight of this curious phenomenon. I was the more anxious to have a view of it, as I shall never see it more." The recent transits of Mercury have been chiefly interesting on account of the accuracy with which they have been predicted. Formerly, owing to difficulties of observation, the tables of the planet's motions were so imperfect, that there was no certainty respecting the exact time of the phenomenon. Gassendi was on the watch three days for the transit he witnessed. Hevelius and his assistants were kept waiting at their telescopes four days. Both Halley's and Lalande's calculations were wrong by three quarters of an hour with reference to the transit of 1786. At a later date, the errors amounted to minutes. At length in 1844, Leverrier took the planet in hand, instituted a profound examination into the theory of it's motions, and constructed tables which represent them with wonderful precision. Mr. Mitchel, of the newly-established observatory of Cincinnati, in the United States, remarks of the transit of 8th May 1845 :— " Five minutes before the computed time of the 'contact (Leverrier's), I took my place at the instrument ; the beautiful machinery that carries the telescope with the sun was set in motion ; and the instrument directed to that part of the sun's disk at which it was anticipated the contact would take place. It seemed as if time had folded his wings, so slowly did the moments crawl on. I watched until I was told that but one minute remained; and within sixteen seconds of the time, I had tho almost bewildering gratification of seeing the planet break the contact, and slowly move on till it buried itself, round, and deep, and sharp, in the sun." VENUS. The nearest planet to the earth, and the second in point of distance from tho sun, Venus is the most beautiful of his satellites, and brilliant of the stars. Like Mercury, she 'never adorns the midnight sky, nor has she ever been seen rising in the east while the sun was setting in the west, or on the meridian at either sunrise or sunset. This shows her path to be comparatively near the throne of the great luminary, from whom she never departs more than 48°, rather more than half the space from the horizon to tho zenith; and to be interior to that of the earth, while exterior to that of Mercury, whose greatest elongation, or distance from the sun, is little more than 28°. In addition to this, she has been observed to eclipse Mercury, a clear proof of her position in space being external to him, an instance of which occurred on the 17th of May 1737. Venus is alternately a morning and evening star, visible for about three hours after sunset, and as long before sunrise. As a morning star she was called Phosphorus and Lucifer by the ancients, and as an evening star Hesperus and Vesper. This bright herald of the sun's advance to the eastern horizon, and his faithful follower to the western, were once sup posed to be distinct bodies. Pythagoras is said to have been the first who proclaimed their identity. Obvious as this conclusion now is, it required experience and reflection to arrive at it. The Greek Phosphorus, or the UgJit-bringer, alludes to the office of the planet, when rising before the sun, she ushers in the day. The Romans adopted the expression : hence, the invocation in Martial, Phosphore, redde diem, " 0 Phosphorus, MEKCUBY — VENUS — THE EARTH. 67 restore the day." As an image of the anticipated dawn of full mental illumination, the sacred writers introduce the day-star ; and it occurs as an emblem of mere human glory in the ode on the overthrow of the King of Babylon : — " How art thou fallen from heaven, O Lucifer, son of the morning!" Homer compares the son of Hector to the star that gilds the morn, and the point of the spear of Achilles to the keen light of radiant Hesper. Men of all ages, climes, and ranks, from the shepherd boy to the grave philosopher, have turned with interest and delight to this planet ; and whether examined as a telescopic object, or contemplated with the unassisted sight, it is an inexpressibly lovely orb, and one that will always excite admiration. Venus is situated in the system at a mean distance of sixty-eight millions of miles from the sun, through which she would fall in thirty -nine days and a half, if surrendered solely to the attraction of his mass. Her periodical revolution is accomplished in 224f days, involving a velocity of 80,000 miles an hour. The planet is rather smaller than our own globe, having a diameter of 7700 miles. She rotates upon her axis in about 23^- hours. Venus exhibits alternately a fine thin crescent and a semicircle like the moon, but she can scarcely be seen quite full, because when the whole of her enlightened hemisphere is turned towards us, she is either behind the sun or so near him as to be hid by the splendour of his light. The diagram represents the various appearances of the planet as she moves in her orbit, in the order of the letters. Superior conjunction. East elongation, f} W S^W (U West elongation. — t " a 6 Inferior conjunction. We first behold Venus as a morning star for a short time before sunrise, soon after passing between the earth and the sun at her inferior conjunction, when she appears crescent-shaped as seen through a telescope. She continues gradually to gain upon the sun, rising earlier and earlier, until her greatest angular distance westward has been attained, when she exhibits a semicircle, and shines with great splendour. Then the planet begins to return towards the luminary, making the same daily progress as in separating from him, rising later and later, diminishing also in brilliance, owing to the overpowering solar glory, in which she is lost at the time of her superior conjunction, being then behind the sun in relation to us. A few days afterwards Venus becomes an evening star, and is seen a short time east of the sun after his setting. She soon seems to have fallen considerably behind him, and continues to depart farther and farther, setting later every night, until her greatest elongation eastward has been reached, when she again exhibits a bright semicircle. The course towards the sun is then resumed, until she comes between him and the earth, sets with him, and is invisible, owing to the whole of her enlightened side being turned away from us. In a few days the phenomena of the morning star are repeated. Venus is seen to keep on the same side of the sun for a period of about two hundred and* ninety days together. This seems at first sight a singular anomaly, as it is a greater interval than that occupied by an entire circuit round him It is however at once accounted for by considering that the earth is proceeding at 68 SCENERY OP THE HEAVENS. the same time in the same direction, though at a slower pace. The planet accomplishes an angular motion of 1° 36' per day, while the earth follows at the rate of 59', and is thus gained upon by only 37' daily. But the two planets will obviously appear to keep on the same side of the sun, until Venus has gained half her orbit in advance, or 180°. This it will require about two hundred and ninety days to effect, as the difference of their daily rate, 37' x 290= 10730'= 180° nearly. It will be seen from the diagram, that at the time of the inferior conjunction, the unenlightened half of the orb is turned towards us. Did she present in that position her illuminated side, we should see the planet as a small brilliant moon, shining with twenty times her ordinary lustre, as she is then a hundred and sixty millions of miles nearer the earth than when at the opposite point. As it is, however, she is our best friend among the stars, the most radiant of the host, and has been observed to cast a clearly defined shadow. This planet, like Mercury, transits the sun's disk, and then appears shorn of her beauty, under the form of a dull dark spot. The first instance of the phenomenon being seen by any human being occurred on the 24th of November 1639, under remarkable circumstances. It was observed by two youthful friends ; Jeremiah Horrocks, at Hoole, near Liverpool, and William Crabtree, at Broughton, near Manchester. The great credit in the observation is due to the former of these individuals, who anticipated the event, and predicted the time. Upon Keppler completing his tables in 1627, he predicted that Venus would pass over the sun's disk on the 6th of December 1631. He died before the time arrived. The transit was looked for, especially by Gassendi, but it was not seen ; and Keppler had distinctly announced that it might not be visible in Europe, as the planet would not be in contact with the sun till towards sunset. It is now well known to have taken place during the night between the 6th and 7th. But Keppler had stated, that after this period Venus would not be seen again upon the solar disk till the year 1761. This was an error. Horrocks suspected it on going over the tables, and comparing them with others. Having repeated his calculations, he found that Venus might be expected to enter upon the solar disk a little before sunset, November 24, 1639. It appears that the time of the transit was nigh at hand when the discovery was made, so that there was no possibility of giving general publicity to the expected event, in an age when communication was very slowly main tained. Though not doubting his own calculations, Horrocks did not deem it prudent to trust implicitly to them. Accordingly, the day before the event was really expected, he watched the sun at intervals ; but only ordinary appearances were noticed. The next day, a Sunday, he attentively observed the solar image from sunrise till the hour appointed for going to church — " higher duties," as he remarks, " which might not be neglected for these pastimes." Upon becoming at leisure, he resumed his observations ; and at a quarter past three o'clock in the afternoon, his sagacity and industry were rewarded. " At this time," he states, " an opening in the clouds, which rendered the sun distinctly visible, seemed as if Divine Providence encouraged my aspirations, when, oh ! most gratifying spectacle, the object of so many wishes, I perceived a new spot of unusual magnitude, and of a perfectly round form, that had just wholly entered upon the left limb of the sun, so that the margins of the sun and of the spot coincided with each other, forming the angle of contact." Owing to the near approach of sunset, his time of observation was limited to about half an hour. Meanwhile, in the neighbourhood of Manchester, the day opened inauspiciously, and continued gloomy to a late hour in the afternoon. Crabtree had abandoned all hope of being able to test the prediction of his friend, till just before going down below the horizon the sun broke through the clouds. Repairing to the room where he had made his preparations, he saw the round black spot with unspeakable delight ; and, according to Horrocks, he was so struck with admiration at the spectacle, as to continue gazing upon MERCURY VENUS — THE EARTH. it, without attempting to take measurements, till it became impossible to do so, owing to the clouds returning. Both observers received the sun's image through a telescope in a dark room upon a piece of white paper. The transits of Venus are of special interest from their rarity and great physical importance. They occur at intervals of eight years, a small section of individual life ; but alternating with intervals of more than a century, during which whole generations pass away, thrones crumble, and dynasties change. They are of importance as the very best means of ascertaining the distance and volume of the sun, which supply data for determining the distances and magnitudes of the planets, and serve as a universal standard of astronomical measurement. The second recorded transit, in 1761, was well seen; but the discordance of the results obtained at different stations shook faith in the accuracy of the observations. For the third and last, in 1769, many of the European governments sent costly expeditions to various parts of the globe ; and among others, Captain Cook was despatched to witness the phenomenon at Tahiti. The next transit will occur December 9, 1874; and though not visible in this country, it will be watched elsewhere with an intensity of scientific solicitude which no natural incident has ever yet excited, and with much better instruments than have before been used. Another will follow after an interval of eight years, December 6, 1882, which will be seen in England, but only partially, commencing near sunset. Venus will not again be seen upon the sun's disk through the whole of the next century, or till June the 8th, 200-i. But little is known of the physical constitution of Venus, owing to the intense splendour with which she shines. The existence of a considerable atmosphere is inferred from the appearance of a penuinbral light round the planet during her transits, as well as from a faint radiance observed to stretch beyond her directly illuminated hemisphere. The line in the annexed uppermost figure marks the boundary of the direct influence of the sun's rays ; and the upper and lower projections beyond it show the twilight, which is referred to atmospheric reflection. Variable and fleeting spots have also been repeatedly noticed, as in the second figure, which naturally leads to the supposition of an atmosphere charged with clouds and vapours, with water upon the surface, from which they are formed. The conclusion that she has mountains and valleys rests upon the fact that the edge of her enlightened part appears shaded, that her corners are sometimes obtuse, and present a luminous point apparently de tached from the planet. Schroeter regarded this as the summit of a high mountain, illuminated by the sun after he had ceased to be visible to the rest of that hemisphere. If these conclu sions may be depended upon, and they are warranted by strong evidence, Venus presents striking points of analogy to the con stitution of the earth. An atmosphere reflecting light, the medium of sound, and a highway for " fire and hail, snow and vapour," — a superficies exhibiting the diversities of land and water, hill and vale — these are some of her probable attributes, features expressing a family likeness to our globe, and indicating the action upon her surface of that mighty upheaving agency, which, in bygone ages, piled the Alps, and reared the ramparts of the Himalaya. 70 SCENERY OF THE HEAVENS. THE EARTH. We now come to the abode of Man — the cradle, the home, and the grave of our race for a period of six thousand years — the third planetary body in point of distance from the central sun, and the first in the system of which we have certain knowledge of its being dignified with the presence of an attendant orb. The introduction of our globe to a place among celestial objects involves an apparent contradiction ; yet such is its real character in the constitution of the universe, and such is its obvious aspect as viewed away from its surface. To rustic ignorance it will seem a statement palpably absurd, that any affinity exists between the earth and the stars in the firmament. They are mere points of light in the sky, and have no perceptible dimensions, whereas our world appears of immeasurable extent, and exhibits no luminosity like theirs to the eye of sense. It seems, too, a perfectly inert mass. There is no movement discernible inde pendent of that of the rivers flowing in their channels, the seas tossing in their bed, and the forests bending to the gale, while the celestial bodies appear in constant procession from place to place in the concave of the heavens. There is nothing, however, more susceptible of demonstration than that the obvious state of our globe is not its actual condition — that the apparently quiescent habitation of mankind is an unceasing traveller in space — that its opaque mass exhibits the same luminous aspect to the nearer planets which they present to us — and that in structure and economy the earth is in fraternal relationship to the celestial host, and may be denominated, with perfect propriety, a star. Physical eciencej in the three departments of astronomy, geography, and geology, deals with the mass of our globe. The former is chiefly concerned with its figure and magni tude, its atmosphere and motions. To the eye the earth appears an immense plain stretching out in all directions to an indefinite extent. This was the current opinion of mankind respecting its form in early times. But a feW simple facts prove the suggestion of the senses here to be erroneous. The limit of vision to the traveller upon an extensive level, or to the mariner at sea, is a well-defined circle of which the observer is the centre ; and it may be geometrically , that this circular horizon is a certain indication of the circular figure of the body to which it relates. Ih any direction in which a ship leaves shore, or approaches the coast, the vessel is observed as if gradually sinking in the ocean, or rising from it — MERCURY — VENUS — THE EARTH. 71 evidence of the convexity of the water between the eye and the object. "VYe also find, that during a lunar eclipse the shadow projected by the earth upon the disk of the moon is always of a circular shape. The common occurrence now of a voyage round the world, proceeding in the same general direction, east or west, and arriving at the same point again, demonstrates the figure of the earth to be either that of a sphere or a cylinder ; and the latter is disproved, and the convexity of the surface shown, north and south, by the gradual declination or rise of the north and south circumpolar stars, as the equator is approached or receded from. Our terrestrial mansion, therefore, is a vast mass of matter of a spherical form like the planets whose round disks are the objects of telescopic observation. The spherical figure of the planetary bodies — a result of the law of gravi tation — is, on many accounts, the best shape they could have assumed. The same phe nomena could not have been offered to their surfaces, with the same machinery, supposing any other form. Had the earth been a rotating cylinder, the solar beams could not have reached its two extremities together, or its general superficies with either extremity. But it is only an approximation to the truth of its actual shape, to speak of our world as having a spherical form. It is not a globe whose circumference is everywhere at an equal distance from the centre, a property essential to a sphere. A process of reasoning led Newton to the conclusion, that the circle of the earth's daily rotation upon its axis being the greatest at the equator, the consequent greater action there of the centrifugal force would produce a bulging out of the surface in the equatorial regions of a yielding mass, and a flattening at the poles ; and this deduction from the laws of forces has been proved to be correct by the actual measurement of the lengths of degrees of the meridian, made with care and precision by the commissioners of various nations. The certain con clusion obtained is, that our globe is an oblate spheroid, an orange-shaped ball, compressed at the poles, and elevated at the equator, having the following dimensions : — Diameter at the equator 7925-648 miles Diameter at the poles 7899-140 — The length of the axis of the poles is thus about twenty-six miles and a half less than the diameter of the equator. It is highly improbable that any error of importance exists in this measurement, founded upon the principle first employed by Eratosthenes, when he attempted to determine the value of an arc of the meridian between Alexandria and Syene. Sycne. 72 SCENERY OF TUB HEAVENS. Sir John Hcrschel considers it unlikely that an error to the extent of five miles can subsist in the diameters ; and the equatorial diameter gives an extent of nearly twenty- five thousand miles, accurately 24,899, as the value of the equatorial circumference. The earth has two principal motions, a rotation upon its own axis, and a translation in space. We can obviously have no ocular evidence of the diurnal rotation like that which we obtain in the case of the sun and some of the other planets, by observing the move ment of spots upon their surface. But we have ample proof of the fact. There is absurdity upon the face of the ancient doctrine, that the daily apparent procession of the heavenly bodies round the earth is a real progress — that a point utterly insignificant when compared with the general aggregate of stars is a centre around which they circulate ; and when we think of the inconceivable velocity with which they must travel, in order to compass the immeasurable circles which in that case they describe, the absurdity heightens. The rotation of our globe is not, however, a doctrine based on probabilities. The experiment of falling bodies descending in advance of the plumb line is direct and positive demonstration of the fact, corroborated by the diminution of the force of gravity at the equator. According to Laplace, the chances are eight thousand to one that the earth so revolves. The rate of the earth's rotation at the equator, where the circle of the circumference is the greatest, is about sixteen miles a minute. Its velocity, at thirty degrees of latitude, which is below the most southerly point of Europe, is computed at fourteen miles in the same time ; and at forty-five degrees, or about the centre of France, it is eleven miles. Laplace has discussed the point with great care, whether the rate of the diurnal rotation is liable to be perturbed, and the time of revolution affected by the influence of volcanoes, earthquakes, winds, and currents in the ocean, and has demonstrated their effects to be altogether insensible. He has also examined the question, whether a variation of the mean temperature of the globe may not have influenced the velocity of rotation, and altered the length of the day. The temperature at the bottom of deep mines indicates a central heat. Geological appearances also intimate a large portion of the crust of the globe to have once been in a state of fusion, and it is a well-known property of heat to cause the expansion of the substances into which it enters. Allowing therefore a former very high temperature, the contraction of the terrestrial spheroid would be a consequence of its cooling down, the diminution of its volume without altering its mass, through the molecules approximating to the centre, causing thereby some change of velocity in the superficial rotation. We have no reason, however, to suppose, that any diminution of temperature has occurred, since man has existed upon the soil, sufficient to produce a sensible alteration in the length of his day and night. All history proclaims its uniform duration, age after age ; and Laplace, who first started this speculation, came to the conclusion, that since the time of Hipparchus, the length of the day has not been affected by the two-hundredth part of a centesimal second. How beautiful the arrangement of the diurnal revolution of cur terrene mansion! How benign the results ! The alternation of light and darkness — the gorgeous sunrise — the resplendent noon — the calm glory of the eventide — the absorption and radiation of heat — and the trade winds, upon whose uniform direction and constant action the navigator reckons on the breast of the ocean. The other principal motion of our globe is its translation in space. This appeals not to our senses like the orbital movements of the surrounding planets, but it is supported by irrefragable evidence. It accounts for the phenomenon of the apparent annual revolution of the sun, as an actual transit in a vessel on the water accounts for the apparent move ment of the banks of a river, or the shore of the sea. It satisfactorily explains the seeming anomalies of the planetary paths. It has received direct confirmation from the aberration of the stars, and may be regarded as established on the firm basis of demonstra- fanftr Thf Ictttrt- Ftaure represents thfAnraial Idi-i '/// tti'ii 1 1 r ' the Earth round thtSun . //i. fii its Oi-lxt whi,h is an Ellipse., the f.rcfittriiit\ ' t'f 'which is about .•?. leagues, and on thr first < • i The Graduated tifje whirhatasmtiD ilistniice surrvunds theyorthPolein fai-h tiuiiii-ofthcEtii-th .shews the l'iinilli-1 »1 'tiniit Kii tain, thif Garde is divided, into ?4 htna-s . The tiqure to the rightmarkt thehour of Sun-rise, that to the left, the hour ot'SwL-set. The point » indicates tlie position, of Great Britain with referaux to tfie. Sunatthe varioue hours oftheltoj,- andNight - for EjcampU. it if 2 O ' Clock ji-M.on the first of June, and the horary Circle shews us thatat this time thehour ot Sun -rife if 4 * 3 mand.that of Sun-set 7 ^52 T thelfiyht therefore will conti- • nue 2* 3"? longer. Ayainonthe first \^j of December the Sunrrises at 7 and Sets of the horary Circle indicates at 4^ 4™ the time supposed being !.• the da)' wiR continue 2 '"• 24 ™ longer Atthis period of the Tear the Earth approaches the IVvitfr Solstice when.itsyorthPoleis en veloped in darkness tor twoMonthf will Am-c reached the middle of its long Night . Suppose, a movinq bodylR* sub jetted to the int oftfo forces One in tlie direction JU, S . the other in the dirrflii'ti HI. -I' the intrnsit\- being mdicatftl by the riaht lines IR, P. anil HLV the moving body can neither i/n towardf S nor JC but must take: an intermediate Course IR. O. with a Velocity represented by lIL,-*-» It if thus rlrar that the mo\'ing body HL. will take the same dirrftian and have the same Velocity of Ons force represe/iteJ in Mnanihule by 111. •*-» at id in direction by IIL O M 'o idd hat e imparted to it . The name Residtant or equivalent force if on ni tf the litr\-eV\t^.Thisat:r^eiiitinit tint-e is supposed to ojt only at the beiiiniiinuufeiii-h moment white the Motion, isitnit'urm tlir I'rrtor Radius ll)i S. then will trust u small truing leU^S A . If this tinre ,-eaxed to art the followi/uf moments the. VeetorEaduu would trate a fresh ftiangle rt^nnl tn thr tirst Hut nt the beginning of the next, momattthe ac force 11^ k combines with'S^'R and cauftf the moving body to ejchibit the eJfects oftherrsijtant force A HI, the sides ofwhirh A/> AB represent thf.fr forces . Apparent position* of the Simat different hours of the day at the, time of the ffmaeett . Fig;. 3. For some time after Sun-set, the rays roll illumine the Atmosphere diffw sinq tharutth'es thrnutjh space and, Niyhtrome.on almost uuttnfibly. this* u callftl twilight anil the dawn is a similar Phenomenon which prectf •des Sun-rife. The So lor ray S-0. whichenifrfthfAlnvisplirreat O. instead of coming out at ^i will be turnedafide, rejrwtrdorbKnt more and more, as itpeneiratcs the vari ous Strata of Air. and will at last reach the Earth iliwribinii the Curve O.G. The Observer •atGnvuldthus seethe Sun much lonperaiE thanhe The effect, o fthe dawn is the. reverse j fthis -let the Earth be reprufcnted hj-AB.C-D.and.lr.whenetJieSu/i.-rieei: the horizonat H.GRm» »•«»• tight from all parts ofthe.Hea\ -ens either directly trb\- reflection. the point A at which, the limhtif not actually n ftii, has above, its horizon the lenticular portion oftheAfc •mosphere K.LR. indirectly ilhurunated, the dawn if most brilliant at K . the tint bewming more feeble until it reaches R. '.<• utmost limit aboi-e thehorujonatSi. it ... ~.,...,andtit D where the Sun isRifiny thewholeofihf horizon if illuminated while at C. the. lenticular portions of theHeM'ens T.3TX. r v,ily-receivelight.T^e^rffntof&i^$itissht*vn, onthrtiaiirebyaZoneofUghtershadethanthatwhuh' , .marks Nipht . Supposed fkeNeridianof London. . 29 in an opposite direction toherorhiciiliir [motion . Let the Moon. L.&g.G.beata point of her orbit L-n.befow the ecliptic. advancing towards MTOMMMM node the Suns attraction will be in the direction J..S. tKe intensift' of this force being represented bv the line L.a.it may he decomposed into two forces one.L.T towards the centre of the Earth, the other. LJD. towards the plane of the ecliptic . the action of these two forces would give the Moon an intermediate direction . L.x.o. and cause her to cross soot er the plane 01 the ecliptic . The arc described above theh raon oy the Moon in su/nmer appears much smaller the,, that described by her in winter: it is thus ejcplainfd on the night of the waiter solstice 21? or 22'tliecember the Earth ' T fir 2 sees the Sun, understand the phenomena e.rhibiJed bv the Jloa/i. the most on the Jfwris phases, that, a spot i-lenrlv distinguishable bt the naketi eye upon hersw face, when at the ridl. » /// be with diftiadh' disnmed iien b\ the alas.* towards the last quarter . Thf iippftimnccs obsen-iil on the Moons surface are t-ansed. either l>\ difference of let'cl.or PV differ encr of the intensity of the liaht . The lif/ht ret lected mm the sun'ace of the Moon is plainly fi-n tr> be of different shades: although the tiaht •fr parts are generally the niountains.it the dark •er ones the low plains . still.airtrid obscn-aaon.' have shown that this ijt not iilwqvs the case. but that, the streaks or 'light. whicii at the full surpass in bri/liann • all the adjacent parts, some -times e.rist entirely independent of mountains. and extend alike over heights and valleys with out beina affettetl bv them . Besides differmce in intensiti- or' the light, colours specirit-aUy differ •ait may be observed. particularly gnvn .sometimes ii colour of a redilish tint. at others a yellowish brown. The derations ofthelfoon are in fieneral or' a much more />recif>itoiis nature than those of the eajfh.ln the plate, the edges of the steeper craters, more especially those or'small e.i-tent.aretjeneralh' shown b\' a plain iint- the narrow dais orrwines bv paralel lines without a cross tint . The middle edge or' thf Noon. i.e. the great circle which in the mean lilavtion seperates the hemisphere which is visible rrorn that whicii is invisible is iiivesmirilv delineated in ruiaile. Chains of miHintains. or mountainous regions of any importain-i: namfti after the inoiaitams of the mrth.and the various spots after d/stiniiitishfil men. on unne.n'd . To avoid confusina the objects in the plate bv a profusion of figures . the Moon's surface is divided into ft parts, the numbering of tlie spvt.t in eacJi (vmmeniina with unit . S < A L K 2.'' Htiutat 49 LeMoimui- 26 PivnLAuanun 50 M.Hadla- T, PicanT 28 Janfat 2!< Plvdus :'.« .(/aniliu* 31 Alluaai 52U£nuUe* 53 HaJm 54 BerosiLt 55 Trailer 56 Bwidiardt 34 "Mafrobius 58 Bernouilli 35 fio-uriuf 5$ Posidonius 36 .Waraldi 60 Autoh'cus 37 Littrov 61 AristUlus 38 Pnxn,frdtmtsia62 Gauss 39 raj/uet 63 Messala J2 Alliaza 33 Produs tijpiiui Kratn 27 MJbgraau ?."> ftiatau 30 Lambert Aristardi 33 Berodot . 34 Timodians 35 L,iiiire 36 Diopkantas 37 Brioas WHdiam 10 Carlini 41 Ddisle 42 VoUaston 43 Lit-Jitetdteri.1 44 ITlttAjh Betiih 45 La\-oisiei" 46 Puv 41 ProiiiJ,ui>lii< 48 BeniaSk* 85 Strabo 86Thale* 87 Gartner SSDanoait 89Archvtns 90 Arnold 91 Meton 92 Barrow 93 Eiutemon 94 Sforesbi 95 Gioja 49 Matron 50 Sharp 51 Lom-ille 52 Sordino 53 Gerard* 54 Plato 55 IfauperOus 56 Condamine 51 BianduM Ml 34 Piitet 35 Trdio 37 ilivntius 38 Sassaides 39 Hrvwiuf 40 Eainn-l 41 flrebbei 42 LeJmiunii 43 Bouvard 44 LejxU 59 Rarpabis 60 Oenopiaes 61 Kef sold 62 Fonttnelle 63 Horrehou 64 Trinuiu- 66 Xmopharu-s 67 Anajamander 68 Pyttuiuorns 69 Epiaaies 70 anajaufenir 7J PhilobMis 72 Ann.rimt!ti,-x 6t> Byraatt 67 'fliebit 68 Arzajchcl 10 Bnffialj" 72 liuxsniili 73 Jfersenius 74 Alpetmijiii; 75 Alplwii* 76 BOlv : Fontana 45 (lauriiut- 11 Fontana 16 Wurzdbuuer 78 Sirsalu 47 Culms 13 (ruaer 43 tapiuuuis 80 Pfoletnau.'; 49 Ptazzi 81 Davy 50 Liujranae 82 Mienkr 51 Walter ' 83 Fa* . 52 &nionwntanus 84 Bi'ripland 85 f.iiaides 86 Letrvnne 81 Hunsteeii 89 r.nl,intl,- 90 Fra Mawv 59 lii'ppelmater 91 Plamsteni f>O Fouriei- ' 92 Damotfeau 61 Pitta 93 tirinuiltli 62 Purb,idi 94 JfMa'rw 63 Eies 95 Lundjfbtf-tj 64 Hiiniulus 96 Lohrniuifn 65 lai-indifh 97 ffiwoli 57 Palitisdi 58 SneHius 59 Petai-iu.1 60 Borda 61 Pucolomini 62 Pontanus 63 H'ernir 64 Apianus 65 Eekatauf 66 Biof 6t Santbccn 68 Frafastor 69 Pob-6ius 10 Ftrnhit 11 S 3 .ibatfzni 74 Plavraif 75 LaCaille 76 Behaim 11 78 Cook ~/l Sfuaafmau 79 Colombo 52 Poisson 80 Bi •hiutibfrpa- 53 .///<•<•«.« 54 Humboldi 55 Li-urndrr 56 Ha.tr 81 Beaumont 82 Catharina 83 Taritus 8-t Almanon 85 Abulfeda 86 G,-ber 87 Airy »*># Auatnu 8ft Ltipn-rousr 90 Jfagtitiafns 91 (\riUiis 92 Theophiln.-! 93 Eant (>4 Desmrtes 95 Dotlond 96 Parrot Hi Albatfaniuj 9ft Uaeiaitrin 99 La/iorenitJi tt>i> Messier li'l Goileniiis 102 I'liitti-mbrro 103 Capi-lla ' 1 Venus T7ff, Mars 1|, Jupiter 5]-, Saturn 9£, Uranus 19, Neptune 30. This diversity of position must produce diverse physical effects ; but even to the farthest planet the Sun is still a SUN, and will afford an illumination several hundred times surpassing our largest supply of lunar light. The apparent diameter of the sun, as seen from the earth, is 32'. As seen from the other planets, it will be, Mercury 80' Venus 46' Mars 21' Jupiter 6' Saturn Uranus Neptune 60" The comparative size of the solar orb from these several stations may be thus pictorially expressed : Mercury. Earth. Mars. Jupiter. Saturn. Uranus. Neptune. While a motion of translation in an orbit and one of axical rotation belong to all the planets, as far as observation has gone, constituting to each respectively its year, and its day and night, the length of these periods widely differs, as the annexed table shows : — Length of Day and Night. 24h 6m 23 23 24 9 10 21 56 30 56 30 Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune The planets are spheroids more or less oblate, but their magnitudes vary prodigiously. Taking the earth as 1, the comparative volume of Mercury will be ^5-, Venus f, Mars £, Jupiter 1330, Saturn 857, Uranus 88, Neptune 107. Their apparent diameters, as seen from the sun, will be, Mercury Venus Earth Moon Mars Jupiter Saturn Unmus Neptano 16" 30" 17" "2 unknown unknown O - 0 1 1 - 11 - 29 - 84 - 164 Length of Year. Years. Months. Days. 2 7 0 10 10 O 0 0 28 15 O 21 17 0 0 0 4" -6 10" 37" 16" Their relative bulk may be brought before the eye as they are represented on the next page. To express the proportionate volume of the sun, a circle with nearly a diameter of one foot would be required. The following illustration of the relations of the sun and his attendants is taken from Sir John Herschel and Dr. Nichol. If we conceive the sun to be a globe two feet- in diameter, then a grain of mustard seed, at eighty -two feet distance, 106 SCENERY OF THE HEAVENS. will represent the size and place of Mercury. A pea, at the distance of one hundred and forty-two feet, will be the similitude of Venus ; and another, slightly larger, at two hundred and fifteen feet, will be the appropriate representative of the earth. A good pin's head, removed three hundred and twenty-seven feet from the central globe, will stand for Mars ; and a few of the smallest grains of sand, placed at the dis tance of five hundred feet, will denote the Asteroids. An orange of moderate size, distant a quarter of a mile, will indicate Jupiter. Saturn may be shown by a lesser one, at two-fifths of a mile ; and Uranus by a cherry, at three Jupiter, quarters of a mile. There are renwkable differences as to the material of the solar and planetary orbs. Their weight, compared with that of the earth taken as 1, is, • Mercury. O Venus. © Earth. o Mara. Venus Mars Jupiter 338 Saturn 101 Uranus 14 Neptune 19 Saturn. Uranus. Sun Mercury 355,000 535 Their weight, compared with that of a globe of water of the same size, is estimated to be Sun Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune What striking diversities ! While our planet, weighed in the balance against an equal volume of water, is five times heavier, the matter of Mercury is three times heavier still, while that of Saturn has only half the density of the fluid. If cast therefore upon an ocean capacious enough to receive them, Mercury would sink with as great a momentum as a globe of lead, while Saturn would be buoyant as a vessel of cork upon the deep. Upon the magnitude and density of the planetary spheroids, the force of gravity or the weight of bodies at their surface depends. Hence, though the solar substance is so much less dense than that of the earth, yet, owing to its vast bulk, a man weighing 140 pounds at the terrestrial equator would weigh more than 3500 at the surface of the sun. Jupiter is still less dense, but on ac count of his superior magnitude the force of gravity at his surface is eight times as great as at the earth's, so that a terrestrial inhabitant transported thither would be burdened with eight times his present weight, would move with eight times the difficulty, and would fall with eight times the force. But upon the diminutive telescopic planets, owing to their feeble gravity, a race of terrestrials might play such high fantastic tricks as would realise the dreams of fairy legends, bounding across a chasm of no trifling span, with the same muscular effort as here will only enable us to compass a step, and alighting with no greater shock than is felt in one of the paltry leaps of childhood. We may however infer a nice adjustment between the planetary worlds and their respective occupants, from the beautiful adaptation, which meets us here, of the constitution of man, animals, and plants, to the circumstances of their dwelling-place. Supposing that constitution to remain the same, and the earth's volume to be increased to the size of Jupiter ; the intensity of the force of gravity would suspend the functions of animal and vegetable existence. The tiger would cease to spring upon his prey from the sheer impossibility of doing it ; the swift gazelle would become a laggard upon the plain ; the soaring flight of the eagle would terminate ; the sap would fall in the trees to rise MAES — PLANETOIDS — JUPITER — S ATUKN — U It ANUS — NEPTUNE, 107 no more ; plants and flowers would be unable to circulate their juices ; and man himself would sink down to the level of a slow-moving quadruped like the sloth. There is thus with us an express adaptation of the varieties of living existence to the magnitude and circumstances of our globe ; and it is philosophical to accept this fact as a guarantee that a similar adjustment obtains throughout the system with which we are connected. And whence this adjustment ? Whence this marvellous proportioning of the power of the humble crocus peeping above the snow, and the magnificent rein-deer bounding across it, to the earth's volume and mass, so that the force of gravity is not too strong in the one case for the development of the flower, nor muscular energy too great in the other for the purposes of the animal ? Epicurus, upon reading the well-known lines of Hesiod in his youth — " Eldest of beings, Chaos first arose, Thence Earth wide-stretch'd, the steadfast seat of all The Immortals, — is said to have proposed the natural question to his preceptor, " And Chaos whence ? " The philosopher originated a theory in his riper years which assigned the creation to a fortuitous concourse of atoms ; but how natural the inquiry, overlooked by the theory, " And atoms whence ? " A sober understanding will not stop short of recognising a presiding Providence in adapting the economy of terrestrial life to terrestrial conditions ; and even so are we warranted, from the evidence of what is near, to look upon the remote, as the scene of similar adaptations, the operation of the same First Cause. In regarding the planetary worlds as the abodes of sentient life and of forms of existence kindred to those which occupy the earth, we are in advance of what is written, or what observation detects, but not beyond what the sobrieties of reason will justify. It may be hard to imagine how life can be sustained under the apparent heat of Mercury, or amid the seeming cold, the tremendous storms, and rapid atmospheric changes of Jupiter. But, ignorant of facts, a parallel difficulty would be a stumbling-block to us, in relation to our own planet, when we consider the high temperature of its equatorial regions and the intense cold of its polar circles. Yet we have great families of men and animals in each extreme. "We meet with human life upon the sultry plains of Delhi, and on the ice-bound shores of Greenland ; and where the citron, the myrtle, and the palm will not flourish, the pines, the mosses, and the lichens grow. It is impossible to naturalise the elk in England, owing to its warmth ; and turn the giraffe adrift, and how long would it survive the chill of the climate ? Yet each animal, in circumstances to which it is adapted, is stately and vigor ous. All the planets are plainly of one family as to their physical character, their general configuration, their motions of revolution and rotation, and the alternation of day and night ; and these are resemblances which may reasonably lead us to suspect other analogies. The fact is also clear, of Mercury, Venus, Mars, Jupiter, and Saturn being surrounded with atmospheres ; — a constitution which strongly indicates their occu pancy with some varieties of organised being. We know, in the case of our own globe, the important uses of its atmosphere in maintaining animal life, transmitting sound and light, and in advancing the arts which tend to civilise society. Without such a gaseous envelope, bound inseparably around the earth, its partner in all its motions, — yet no ema nation from it, but a separate element, — the ear would have no office to perform, the tongue would be speechless, and the service of the eye be greatly abridged. The song of birds, the hymns of religion, the eloquence of senates, and the utterance of relative kind ness would perish. The fiercest waves would dash in sullen silence upon the strand ; and mankind would have no medium of inter-communication beyond that of sign and gesture. We may well believe, therefore, that our world has been furnished with this elastic and essential apparatus, in order to adapt it for the reception of animal existence 108 SCENERY OF THE HEAVENS. and intelligent inhabitants ; and the inference is just, that a similar arrangement distin guishing other planets, points to the same destination. It is a possible conception, — but we should smile at the credulity of the man who believed it real, — that a fleet of ships navigating the ocean, with sails unfurled and pennons flying, did so without a cargo in the hold, a crew on board, or an object in view. CHAPTER V. COMETS. F all the celestial objects which have arrested the attention of mankind, none have excited such general and lively apprehen sion as those upon the consideration of which we now enter. Undoubtedly their sudden appearance, rapid movements, and occasionally extraordinary aspect, were calculated to awaken terror in ages of ignorance and superstition, and to originate the wild conjectures that are on record respecting their cha racter and office. The Romans regarded a comet which was seen in the year 44 before our era as a celestial chariot conveying the soul of Caesar, who had been assassinated a short time before its advent, to the skies. Cometary bodies have been deemed the vehicles in which departed spirits are shipped by their guardian angels for the realms of Paradise ; and on the other hand, they have been viewed as the active agents of natural and moral evil upon the surface of the earth, and been formally consigned to ecclesiastics for excommu nication and cursing. A volume of no inconsiderable dimensions might be compiled, and not without interest, from the accounts of old chronicles respecting their appear ances, registering the quaintly expressed opinions of the chroniclers concerning them, the terrestrial events they have tacked to them as effects to a cause, and the deportment to which men have been moved by the apparition of " the blazing star Thrcat'ning the world with famine, plague, and \var : To princes, death ; to kingdoms, many crosses ; To all estates, inevitable losses ; To herdsmen, rot ; to ploughmen, hapless seasons ; To sailors, storms; to cities, civil treasons." We have the word comet from the Greek xo/xn, or hair, a title which had its origin in the hairy appearance often exhibited, a nebulosity, haze, or kind of luminous vapour, being one of the characteristics of these bodies. Their general features are a definite point or nucleus — a nebulous light surrounding the nucleus, the hair, called by the French cheve- lure — and a luminous train preceding or following the nucleus. Milton refers to one of these attributes in a passage which countenances the popular superstition : — " Satan stood Unterrified, and like a comet burned, That fires the length of Ophiucus huge, In th' arctic sky, and from its horrid hair, Shakes pestilence and war." Anciently, when the train preceded the nucleus, as is the case when a comet has passed its perihelion, and recedes from the sun, it was called the beard, being only termed the tail COMETS. 109 when seen following the nucleus as the sun is approached. This distinction has clisap- peai'ed from all modern astronomical works, and the latter name is given to the append age, whatever its apparent position. Neither this luminous attendant, the tail, nor the nucleus, are now considered essential cometary elements, but all bodies are classed as comets which have a motion of their own, and describe orbits of an extremely elongated form. There are several plain points of difference between comets and planets. The planets move in the same direction from west to east, which is astronomically called direct motion ; but the movements of comets are often from east to west, or retrograde. The orbits of all the planets are confined to a zone of no great breadth on either side of the ecliptic ; but the paths of comets cut the ecliptic in every direction, some being even perpendicular to it, traversing the heavens in all parts. The contrast is striking likewise between the forms of their respective orbits. A hoop will with no great inaccuracy represent the courses of the planets, but cometary paths are of every possible eccentricity, both elongated ellipses and open curves, as parabolas or hyperbolas. Only one end of the ellipse lies within the limits of the system, in the case of the great majority of comets with shut orbits. They only visit our gaze therefore during one part of their course, and that a very small part, travelling during the rest of their journey far beyond the range of the most distant planet, into spaces inaccessible to our sight. Those which describe parabolas and hyperbolas are casual vistors only ; and depart to return no more. Planetary con figuration is also uniformly globular, but the external appearances of comets exhibit great diversities of form, from that of an irregular wisp of cloud to a simple spherical luminosity, or a strongly- defined scimitar-shaped aspect. Most of the ancients, following Aristotle, regarded comets simply as meteors born and perishing in the atmosphere of the earth. Seneca, however, clearly classed them with the enduring realities of nature, having a definite path, and not wandering uncertainly through a transient existence : " I cannot believe," he observes, " that a comet is a fire suddenly kindled, but that it ought to be ranked among the eternal works of nature ; it has its proper place, and is not easily moved from thence ; it goes its course, and is not extinguished, but runs off from us ; " and in a passage already quoted, he anticipates the arrival of a Newton or Halley to determine then: orbits, and the laws of their motions. Tycho Brahe took the initial step in the path of true discovery by assigning them a place out of the terrestrial atmosphere. By careful observation of the comet of 1577 he proved its extra- lunar position in space. It yielded no sensible diurnal parallax, and was therefore beyond the region of the moon. Hevelius next ascertained the concavity of the orbits of comets, which Keppler had supposed to be straight lines. Newton succeeded in demonstrating that comets are guided in their movements by the same principle as that which controls the planets in their orbits, as the law of gravitation admits of revolving bodies describing any one of the conic sections, or the four curves, the circle, ellipse, parabola, and hyperbola. Halley finally, after a laborious comparison of elements, arrived at a measurable ellipse as the orbit of one of these bodies ; and predicted the periodic return of the object, which has twice appeared at the time appointed to verify his conclusion. The diagram represents a part of the path of one of the long period comets, that of 1680, obviously but a very small part, as it was described in little better than two months, and the periodic time is supposed to be not less than five hundred years. The direction of the luminous train or tail is shown, the frequent attendant of cometary bodies. This is nearly always away from the sun, frequently assuming a curved form. It increases in length with its proximity to the solar body, but does not acquire its greatest extent until after the perihelion or the point nearest to the sun is passed. If we regard the train as vaporisation produced by the intense heat to which the body of the comet is exposed upon approaching the sun, this accounts for its increasing length and greatest extent after the perihelion, just as it is after 110 SCEXEKY OP THE HEAVENS. the summer solstice that the earth attains its highest temperature, although its daily supply of solar influence is then actually diminishing. The comet appears in the diagram at its perihelion passage merely for the sake of illustration, as in that part of its course it was completely lost in the solar blaze. In the other positions it was observed at the times stated by Cassini, Newton, Halley, and Flamstead. Cometary statisticians have compiled a record of between six and seven hundred appearances since the commencement of the Christian era. But little dependence can be placed upon this enumeration, as simple me teors and such phenomena as new stars were confounded in former times with true comets, and instances of the re-appearance of the same body are no doubt included in the return. In about 200 instances, the orbits have been ascertained with more or less certainty. Of this number, forty appear to have described ellipses ; seven hyperbolas ; and a hundred and fifty parabolas. The ellipse is an oval which admits of every possible degree of eccentricity, or deviation from the circle ; the hyperbola is an open curve, the branches of which may be considered straight lines indefinitely divergent ; the parabola is an open curve, the branches of which extend in a nearly parallel direction, never converging. Consequently the elliptic comets are regular members of the solar system, with periodic times, some of them never wandering beyond the planetary orbits, while the hyperbolic and parabolic comets appear within its limits, depart, and return no more, unless thrown by some disturbing force into a new path. The three features of nebulosity, nucleus, and tail, are usually assigned to cometary bodies, but many are destitute of the latter appendage, and also without any clearly defined nucleus. They appear as simple nebulosities, globular masses of vapour, having no central condensation, through which the feeblest of the stars readily shine. Herschel perceived a star of the sixth magnitude through the centre of the comet without nucleus of the year 1795 ; and a star of the eleventh magnitude was perfectly distinguished by Stmve through the middle of one of the short-period comets. Others present a nucleus strongly defined, with surrounding nebulosity, the "horrid hair" of poetry. The vapoury envelope is dim towards the central point, but suddenly becomes luminous at some distance from it, so as to resemble a ring resting in equilibrium around a star, like the ring of Saturn. The cometary nuclei often shine with a light as vivacious as that of the planets, and exceed them in splendour upon nearing the sun. They vary considerably in their diameters, but are in general very small The measurement of the diameters of five given by Arago range between thirty-three miles and three thousand two hundred. The external appearance of other comets exhibits the three features combined, and these are remarkable objects, occasionally presenting a terrific aspect. Immense spaces are sometimes covered by the luminous trains, or tails, as much as ninety or a hundred degrees ; so that while the nucleus has been below the horizon, the train has reached the zenith, stretching through an extent of nearly a hundred and fifty millions of COMETS. ] 1 1 miles. The tails appear to stream from that part of the nucleus which is farthest from the sun, but seldom in the direction of a straight line joining the two bodies. They generally exhibit a sensible curvature, bending towards that region of the heavens last quitted by the comet, and cases have been observed in which they have formed a right angle with the nucleus. The figure represents their common form, the arrow showing the direction of the comet's motion, and the dotted line the direction of the sun. There is great enlargement in the breadth of the tail, as its distance from the nucleus increases ; and an obscure stripe appears passing down the middle, which has suggested the hypothesis of a hollow luminous cone. It is • obvious that whether comets shine by inherent light, or reflect the solar rays, if the train be a hollow cone, a much greater number of nebulous particles will be in the direction of the eye at the sides than at the centre, which will account for the interior dim stripe, and the exterior brightness. Comets, however, are by no means confined to one train each, but as many as six have been observed appended to the same nucleus. While these variations of form may be due in a measure to different velocities, it is clearly ascertained that the aspect of the same cometary body undergoes great changes in its period of revolution. In recognising two apparitions as appearances of the same body, after having accomplished its periodic time, astronomers do not depend upon the circumstances of shape, size, or brilliancy being similar, but upon the elements of the path being accordant. Towards the close of the year 1680, a comet, illustrious on account of its observers, and apparently formidable from its aspect, appeared within the visible limits of our system, and approximated nearer to its centre than any other, except the remarkable comet of 1843. It finally vanished from terrestrial gaze in the month of March 1681, and has not since been seen. The mind of Europe was profoundly impressed with the vast size, velocity, and form of this object, which engaged the accurate observation of Flamstead and Cassini, and the mathematical science of Bernouilli, Newton, and Halley. After its perihelion passage, its appearance, as seen from Paris and particularly from Constantinople, was most imposing. The train reached to the zenith when the nucleus had set below the horizon, coruscations attending the whole length of the luminosity, giving to the phe nomenon the aspect of a wrathful messenger, and not that of a tranquil body pursuing a harmless course. The greatest length of the tail was computed to be 123 millions of miles, and in two days an extent of 60 millions of miles was emitted from the nucleus. Its average velocity was upwards of 800 thousand miles an hour. A traveller through our heavens, covering such a space, and rushing with such speed through the firmament, might well excite the astonishment of mankind. It must not be imagined that this rate of motion is its average orbital velocity. In obedience to the Keplerian law its pace slackens in receding from the sun. According to the computation of Newton, this body approached the sun within the 163rd part of the semidiameter of the earth's orbit, being rather more than half a million of miles from his centre, and not more than 144,000 apart from his surface. If the projectile force had been stopped, in three minutes it would have closed with his mass. In such a situation it must have been exposed to a temperature which in an instant would dissipate any substance with which we are ac quainted. Newton calculated the body of the comet to have been heated to a degree two thousand times greater than that of red-hot iron. This comet is supposed to be identical with the one that appeared about the time of Caesar's death, with that which was seen in the reign of Justinian in the year 531, and with another in the year 1106 in the reign of Henry II. Comparing these dates, we find, from before Christ 44 to 531 leaves a 112 SCENERY OF THE HEAVENS. period of 575 years. Again, from 531 to 1106, leaves a second period of 575 years ; and from 1106 to 1680, a period of 574 years, which Newton supposed to be about its periodic time. If this conjecture be correct, the comet is now winging its flight from the sun far beyond the orbit of Neptune, and will not return from its long pilgrimage to revisit the fountain of light till the year 2255. How vast the circuit ! How opposite the circumstances of the two extreme points of the route — the perihelion, in the immediate neighbourhood of the solar glory — the aphelion, at the probable distance of 13 thousand millions of miles from him! At the far extremity, the sun, if observed by a spectator, would appear simply as a point of light, and at the other extremity the solar orb would be seen nearly filling the whole hemisphere. At thejirst recorded appearance of this comet, it was seen as a long-haired star in the skies of Rome during the games which the youthful Augustus exhibited in honour of Venus and his uncle, the assassinated Cassar ; and while the inhabitants of the capital hailed the object as the Julium Sidus, conveying aloft the soul of the dictator, his ambitious successor secretly regarded it as a presage of his own glory, while apparently falling in with the popular notion. Pliny has preserved to us his published memorial respecting it, which ran as follows : — " In those days during the solemnity of my games there was seen a blazing star for seven days together, in that region of the sky which is under the north star Septentriones : it arose about the eleventh hour of the day, bright and clear, and was evidently seen in all lands : by that star it was signified that the soul of Ca?sar was received among the divine powers of the immortal gods." At its second exhibition, in the fifth year of Justinian, in the month of September, the comet was seen during twenty days in the western heavens with a tail inclining towards the north. The Byzantine writers applied to it the name of Lampadias, because of its resemblance to a burning lamp. Its third visit is mentioned by the chroniclers, who describe it as like the blaze of the sun, having an immense train. At its fourth return, there was a cultivated science able to grapple with its phenomena, and divest them of a super natural character. Upon itsjifth appearance, after more than three centuries and a half from the present have elapsed, if the estimate of the periodic time be correct, Gibbon has speculated upon its course and phase engaging the astronomers of some future capital in the Siberian or American wilderness. Calculating backwards the periodic time, Whiston brought a return of this comet into coincidence with the era of the Deluge, of which he conceived it to have been the agent. He broached likewise the presumptuous fancy of lost spirits being incarcerated in this body, and hurried by it to the extremes of perishing cold and devouring fire, as a part of their punishment. Such chimeras deserve no serious notice. The first comet whose return was predicted and determined made its appearance in our heavens in the year 1682, the year following that in which the preceding had va nished. Though far inferior in magnitude and splendour to its predecessor, it was a considerable object, and has now become in consequence of its associations one of the most interesting bodies of the system. It presented a tail extending through thirty degrees of the hemisphere ; and while science watched its movements, the eye of the populace rested upon its form without alarm, as the former had signally failed in causing any direful catastrophe. The views of Newton who had spoken of the older bodies as planets without tails, and of comets as a species of planets revolving about the sun in very eccentric orbits, had arrested the attention of Halley ; and probably his remarkable achievement was suggested by the following passage in the third book of the " Principia," — "I leave the transverse diameters and times of revolution to be determined by the comparison of comets which return after long periods of time in the same orbits." Upon this hint Halley commenced calculating the orbits of all the comets upon which definite COMETS. 113 observations had been made, twenty-four in number, for the purpose of comparing their elements — a work of immense labour and difficulty, of which the present Astronomer Royal has remarked, that in all probability he was the only person then in existence who could have performed it. He found the elements of two comets to coincide with tolerable exactness with those of the comet of 1682, as follows : — a b c d e / 9 h 1531 1607 1G82 49° 25' 50 21 51 16 17° 56' 17 2 17 56 301° 39' 302 16 302 52 56,700 58,680 58,328 Aug. 24 Oct. 16 Sept. 4 107° 46' 108 5 108 23 Retrograde a. Year of the comet, b. Longitude of ascending node. c. Inclination of the orbit, d. Longitude of the perihelion, c. Perihelion distance from the sun, that of the earth being 100,000. / Time of the comet arriving at its perihelion distance, g. Distance from perihelion to ascending node. h. Direction of the comet's motion. The general elements here are pretty closely analogous. With reference to the periodic time, there is, from Aug. 24. 1531, to Oct. 16. 1607, - - 76 years 53 days, Oct. 16. 1607, to Sept. 4. 1682, - - 75 years wanting 42 days, a difference of about fifteen months. This Halley conjectured might arise from the dis turbing action of the planets, a correct idea, and one of great sagacity, as the theory of planetary disturbance was but then in its infancy. Upon these data, therefore, he ven tured the conclusion that the three appearances were returns of the same comet, which would reappear after the lapse of a similar interval. His words are : — " Nothing seems to contradict this my opinion, besides the inequality of the periodic revolutions, which inequality is not so great neither, as that it may not be owing to physical causes ; for the motion of Saturn is so disturbed by the rest of the planets, especially Jupiter, that the periodic time of that planet is uncertain for some whole days together. How much more, therefore, will a comet be subject to such like errors, which rises almost four times higher than Saturn, and whose velocity, though increased but a very little, would be sufficient to change its orbit from an elliptical to a parabolical one ? This, moreover, confirms me in my opinion of its being the same comet, that in the year 1456, in the summer time, was seen passing retrograde, between the earth and the sun, much after the same manner ; which, though nobody made observations upon it, yet, from its period and the manner of its transit, I cannot think different from those I have just now mentioned. Hence I dare venture to foretell that it will return again in the year 1758." Subse quently his tone grew more decided. Historical i-ecords supplied some further links to the chain of cometary appearances after nearly the same interval. Thus : — Years of comets - - 1155 1230 1305 1380 1456 1531 1607 1682 Intervals .... 75 75 75 75 75 75 75 The astronomer was confirmed by this evidence in the accuracy of his prediction, and called upon all posterity to remember that an Englishman had announced it. The pro phecy was no random guess. It was not founded merely upon the coincidence of the dates, but a result obtained, in the case of the last three comets, from the close agreement of the elements of their orbits. Great curiosity was excited as the year 1758 approached, to ascertain whether the prediction would be verified. No doubt existed upon the subject in the scientific world, but some apprehension was felt lest circumstances should be unfavourable to a perception of the phenomenon. " "We cannot doubt," observed Lalande, in 1757, " that it will return ; and even if astronomers should not see it, they will not be the less persuaded of SCENERY OP THE HEAVENS. its return. They know that the faintness of its light, and its great distance, perhaps even bad weather, may keep it from our view ; but the public will find it difficult to believe us ; they will put this discovery, which has done so much honour to modern philosophy, among the number of predictions made at hazard. We shall see dissertations spring up again in the colleges, contempt among the ignorant, terror among the people, and seventy-six years will elapse before there will be another opportunity of removing all doubt." Lalande engaged with Clairaut and Madame Lepaute in calculating the attractive influence of Jupiter and Saturn upon the comet, which might change to some extent its time of perihelion. " During six months," he remarks, " we calculated from morning till night, sometimes even at meals ; the consequence of which was, that I contracted an illness which changed my constitution for the remainder of my life. The assistance rendered by Madame Lepaute was such, that without it we never could have dared to undertake this enormous labour, where it was necessary to calculate for every degree, and for 150 years, the distance and force of each of the two planets with respect to the comet." They finally announced in November 1758, just as astronomers began to look out for its return, that the comet would employ 618 days more to return to the perihelion than on the preceding revolution; namely, 100 days from the effect of Saturn, and 518 days from the action of Jupiter. The perihelion was placed therefore about the middle of April 1759, but Clairaut distinctly forewarned the world, that being pressed for time, he had neglected small values, which collectively might amount to, more or less, about a month in the seventy-six years. The event realised the anticipation of Halley, and answered as nearly as possible to the calculations of the French philosophers. The comet was first seen from the neighbourhood of Dresden by George Palitzch, a respectable landowner, but a self-educated astronomer. This was on Christmas-day 1758, with an eight-feet telescope. It was afterwards seen at Paris, Leipsic, Lisbon, and Cadiz. It passed its perihelion on the 12th of March 1759, exactly a month before the time announced, but within the assigned limit of divergence from that date. The elements of its orbit proclaimed it to be the comet of the former periods by their similarity. The following is Lalande's deduction, the letters indicating the particulars connected with the table already given : — a b c d e f h 1759 53° 46' 17° 407 303° 8' 58490 March 12 Retrograde. Another period of revolution has transpired since the time to which we are referring. Dating seventy-six years forward, we are brought to the year 1835. After estimating the action of the planets, Damoiseau, of the French Board of Longitude, fixed the perihelion passage on Nov. 4th of that year, and Pontecoulant on Nov. 13th, a difference of nine days. Both agreed that the first appearance of the comet would be in the early part of August, and the perihelion certainly about the middle of November. The comet was seen at Rome Aug. 5th, and passed its perihelion Nov. 16th. The fictitiousness of the representation, " A pathless comet, and a curse, The menace of the universe ; Still rolling on with innate force, Without a sphere, without a course," has thus been demonstrated, and these bodies proved to be constituent members of our system, obedient to the law of gravitation, which keeps them within prescribed limits and in definite orbits, as with bit and bridle. We may now glance at some of the appearances of this comet at its successive returns, as far as historical records supply information. The comet of 1006 is conceived on good grounds to have been identical with that of COMETS. 1 15 1682. Its first recorded appearance was thus immediately prior to the Danish invasion of England, and during the declining days of the empire of the caliphs. Hali-ben-Rodoan mentions the immense curved tail in the form of a scythe. The head appeared four times as large as Venus. The second visit, which must have been about 1082, in the reign of the Conqueror, is unrecorded : and the third and fourth, in 1155 and 1230, are merely mentioned by the annalists, without any detail. Its fifth return was in the year 1305, when the papal chair was removed to Avignon, the Swiss cantons were effecting their independence, and Edward I. tyrannising over Scotland. At the season of Easter, this " great and fearful star," as it was called, was perceived, but so far from raising the temperature, a supposed cometary effect in later times, a general cold prevailed over Europe, and a severe frost in England at Midsummer destroyed the corn and fruits. History gives no particulars of its next visit in 1380, but in 1456 its appearance filled all Christendom with consternation. It passed very near to the earth, and swept the heavens with a tail extending over sixty degrees, in the form of a sword or sabre. The Turks had just become masters of Constantinople, and threatened an advance into the heart of Europe. The comet variously excited hope or fear, according as it was deemed the friend of the crescent or the cross. At Constantinople, the occurrence of a coincident lunar eclipse increased the portent- •^ ousness of the event. Phranza, ^ grand-chamberlain and principal secretary to the last head of the Greek Roman empire, reports : -^^ — "Each night, soon after sun- j set, a comet was seen like a | straight sabre, approaching the L moon. The night of the full ^^^•fl | moon having arrived, and then | by chance an eclipse having | taken place, according to the re- Hi gular process and circular orbits of the celestial lights, as is cus tomary — some persons seeing the darkness of the eclipse, and regarding the comet in form of a long sword which arose from the west, and travelled towards the east, approaching the moon, thought that the comet in shape of a long sword thus designated, with regard to the darkness of the moon, that the Christians, inhabitants of the "West, had agreed to march against the Turks, and would gain the victory ; but the Turks, also considering these things, became not a little fearful, and had great discussions." The pope, however, Calixtus III., regarded the comet as in league with the Moslems, and ordered the Ave Maria to be repeated by the faithful three times a day instead of two. He directed the church bells to toll at noon, a custom which still prevails in Catholic countries. To the Ave Maria the prayer was added, "Lord save us from the Devil, the Turk, and the Comet ; " and once each day these three obnoxious personages were regularly excom municated. There was perhaps as much worldly policy as superstition in sounding this note of alarm, for fees accumulated to the priesthood from the increase of confessions. The comet at length, after patiently enduring some months of daily excommunication and cursing, showed signs of retreat, and Europe breathed freely when it vanished from the skies. ^ At the eighth return in 1531, the New World had been discovered, and by the invention of printing the foundation had been laid for the intellectual and religious 116 SCENERY OF THE HEAVENS. reform of the Old. The comet as then seen in Cancer was of a bright gold colour. In 1607, the ninth visit, the Copernican system had been broached, and Galileo and Keppler were labouring to establish it. The course of the comet was observed through Ursa Major, Bootes, Serpentis, and Ophiuchus. Its light was pale and watery. The tail is described as long and thick, like a flaming lance or sword. The apparent magnitude of the head was greater than that of any of the fixed stars, or Jupiter ; and, say the chronicles of the age, of its direful effects "the Duke of Lorraine died" — "a great war between the Swedes and the Danes." " The comet does me much honour," was the remark of Cardinal Mazarine on his death-bed, when informed by his servile attendants that one had made its appearance. It is happily said in Shakspeare, in allusion to this sycophancy, " When beggars die there are no comets seen." The tenth return brings us to the time of Newton and Halley. Cassini calls it then as clear and round as Jupiter, referring to the nucleus. At the eleventh revolution in 1759, it was a pale and feeble object. Messier was obliged to use a powerful reflecting telescope. Palitzch, indeed, caught it with the naked eye once, but no one else appears to have done so. In 1835, the ticelfth advent, it was much more distinct, and was frequently seen without a telescope presenting the annexed appearance. Its thirteenth return will occur in 1911, when the present generation shall have passed away, and the few remaining infants of to-morrow be anticipating the infirmities of age. The later apparitions of Halley's comet have thus been far less brilliant and conspicuous than its earlier exhibitions. At its four last periodic returns, it bore no resemblance to the comeeta horrendce rnagnitudinis of the year 1305. Arago conjectures that the comets, in describing their immense orbits, disseminate in space at each revolution all the matter which when near the perihelion is detached from the nucleus and forms the tail. It is clearly possible, therefore, that some of them may in process of time completely waste away, unless by travelling through similar detached trains, they recover a quantity of matter sufficient to compensate for their own losses. We may believe, also, that dissi pation occurring, the same body that now presents an insignificant appearance, exhibited a bolder front in days of yore, though the early annalists and artists have undoubtedly borrowed largely from imagination in describing these bodies. In a celestial atlas published about the year 1680, several drawings of comets occur, from which the annexed are selected. COMETS. 117 It is evident that these artistic efforts are not true to nature, however true to such wild and distorted descriptions as the following, from the " Exempla Cometarum" of Rossen- burg, a contemporary of Newton: — "In the year 1527, about four in the morning, not only in the Palatine of the Rhine, but nearly over all Europe, appeared for an hour and a quarter a most horrible comet, in this sort. In its length it was of a bloody colour, inclining to saffron. From the top of its train appeared a bended arm, in the hand whereof was a huge sword in the instant posture of striking. At the point of the sword was a star. From the star proceeded dusky rays, like javelins or lesser swords, as if imbrued in blood, between which appeared human faces of the colour of blackish clouds, with rough hair and beards. All these moved with such terrible sparkling and brightness, that many spectators swooned with fear !" Before we finally take leave of the comet of Halley, some notice may be bestowed upon his claim to the distinction of being the first to foretell the precise periodical return of one of these bodies. This has been disputed, and assigned to Newton, on evidence recently detailed in one of the leading journals, but which certainly cannot be admitted to invalidate his pretensions. It is affirmed that previously to the appearance of the comet of 1736, Colonel Guise told "Whiston that Sir Isaac Newton had said in his presence, that " though he would not say he was sure of it, nor would publish it, he had some reason to believe that a comet would return about the latter end of 1736." Another witness also, Mr. Howard, is cited, as having heard him make a similar remark ; and upon being questioned concerning it, it is stated that " he seemed to draw back, as sorry that he had said so much, but still could not deny that he had such an expectation." Whiston therefore says : — "As far as we yet know, Sir Isaac is the very first man, and this the very first instance, where the coming of a comet has been predicted beforehand, and has actually come according to that prediction, from the beginning of the creation to this day." Thomson seems to fall in with this idea in panegyrising the great philosopher: — " He, first of men, with awful wing pursued The comet, through the long elliptic curve, As 'long innumerous worlds he wound his way, Till to the forehead of our evening sky Ileturn'd, the bla/ing wonder glares anew, And o'er the trembling nations shakes dismay." This is all the evidence that can be arrayed in favour of Newton ; and obviously its hearsay source, with the dubious tone of the testimony reported, cannot weigh a feather in the scale against the claims of Halley, whose prediction was the result of careful comparison, and as such boldly published to the world. The next most remarkable comet of modern times appeared about the middle of December, 1743, and continued visible during the spring of the year following. On the 1st of February, according to Chizeaux, it was more brilliant than Sirius, the brightest star in the heavens. On the 8th it equalled Jupiter, and was visible in the presence of the sun at the beginning of the next month. By selecting a convenient situation many persons saw it at mid-day without glasses. Several instances of similar brilliancy are on record. Justin mentions a comet which appeared at the birth of Mithridates, and overcame the brightness of the sun by its splendour ; and, however this may be an exaggeration, there are many well-attested cases of these bodies being seen by broad daylight. The Caesarian comet, two others in 1402, with one in 1532, were thus visible. The fine comet of 1577 was seen with the naked eye by Tycho Brahe before sunset. On account of its brightness and peculiar form the comet of 1744 excited great attention and interest. It exhibited no train until within the distance of 118 SCENERY OF THE HEAVENS. the orbit of Mars from the sun ; but, early in March, it appeared with a tail divided into six branches, all diverging, but curved in the same direction. Each of these tails was about 4° in width, and from 30° to 44° in length. The edges were bright and decided, the middle faint, and the intervening spaces as sombre as the rest of the firmament, the stars shining in them. This comet was repeatedly seen in Switzerland, with the nucleus below the horizon, and the six tails extending from twenty to thirty degrees above it. The scene presented by this remarkable body in the situation referred to was striking in the extreme when circumstances favoured the display. In the year 1770 a comet appeared which has acquired considerable notoriety from the alterations which its orbit has undergone. It was first observed by Messier, a man who united great simplicity of character with high scientific attainments. Louis XV. called him lefuret des cometes, from his zeal in hunting after them. He had discovered twelve, every one of which, says Delambre, gained him admission to some foreign academy. While attending to his wife during her last moments, Montagne discovered another. This was a cutting stroke to Messier, and he exclaimed, " Alas, I had discovered twelve, and this Montagne has taken away my thirteenth ! " Then remembering that it was his wife he should mourn for, he began to say, " ah ! la pauvre femme ! " and went on deploring his comet. The elements of the comet of 1770 were calculated by Lexel, who found for its orbit round the sun an ellipse of which the transverse diameter was only equal to three times the diameter of the earth's orbit, which corresponded with a period of revolu tion of five years and a half. It was deemed a singular circumstance that an object having so short a periodic time, whose greatest distance from the sun was not far beyond the orbit of Jupiter, and which shone with a vivid light, should not have been observed before ; and the wits of the day made themselves merry, when, at the expiration of the appointed term, the comet was not observed to return. It has not been seen since ; and was popularly called Lexel's lost comet. But this sport was premature. The previous COMETS. 119 invisibility and subsequent disappearance of this body, after once presenting itself, have been sufficiently explained ; and a confirmation of the laws of universal attraction has been drawn from circumstances apparently adverse to them. Its previous invisibility is accounted for by its orbit being altogether different prior to the year 1770, its nearest point to the sun being as distant as the path of Jupiter, corresponding, not to five, but to fifty years of revolution. Its appearance that year arose out of the fact that in 1767 it was in such close contact with the planet, moving in the same direction and in nearly the same plane, that the attraction of the sun upon it was not ^y$ that of Jupiter. This entirely altered the form of the orbit, and caused the comet to wheel its path towards that of the earth, coming within our view, and executing the ellipse described by Lexel in the periodic time of five and a half years. But why has not the comet since been seen ? Its passage to the point of perihelion in 1776 took place by day ; and in 1779, before another return, it again encountered the vast body of Jupiter, and suffered a fresh orbital derangement, the attraction of the planet deflecting it into more distant regions. The comet therefore, though " lost " to us, is in existence, and in each instance of its change of route has faithfully obeyed the laws of gravitation. Those laws in 1770 introduced it as a bright and beau tiful stranger to the notice of the human race, and again in 1779 stopped the fellowship, removing the comet into a remoter path, where it is hid from the gaze of man, and will be so unless some new perturbation directs its course towards the terrestrial orbit. Another comet, exhibiting some remarkable features, presented itself in the year 1807. It was assiduously observed by Herschel in this country, and by the continental astrono mers, Schroeter, Bessel, and Olbers. The drawings of the two former are here given, taken on two succeeding evenings, which show a divided tail, the separate branches having varied their aspects. Coruscations, flickering and vanishing like the northern lights, appeared to shoot out in an instant from the train to an immense extent. In the autumn of 1811, within the memory of many of the present generation, by far the finest comet suddenly appeared to adorn our heavens, that had been seen since the age of Newton. It was first beheld in this country in the beginning of September, and was visible for more than three months in succession to the naked eye, shining with great splendour, the observed of all observers. This was a comet of the first class in point of magnitude and luminosity. Its brilliant tail, at its greatest elongation, had an extent of 123 millions of miles, by a breadth of 15 millions ; and thus, supposing the nucleus of the comet to have been placed on the sun, and the tail in the plane of the orbits of the planets, it would have reached over those of Mercury, Venus, the Earth, 120 SCENEKY OF THE I1EAVEXS. and have bordered on that of Mars. At its nearest approach to us, the comet was yet distant 141 millions of miles, so that even had the tail pointed to the earth, its extremity Comet of 1811 as seen at Winchester. would have been 18 millions of miles away from its surface, calculations respecting its period of revolution : — Years. 3056 - 3383 - Authority. - Callendrclli - Bessel Years. 3757 4237 The following are the Authority. - Ferrer - Lemaur The mind is astounded at a journey requiring the least of these cycles for its accomplish ment — a period equal to that extending from the fabulous age of Grecian story to the present ; nor is the thought less wonderful, of the chain of solar influence following the traveller through the whole of its course, and preventing its elopement into the regions of immensity. The laws of the system, indeed, impose upon the long-period comets vast differences of velocity. The same body that rushes round the sun at the nearest point of contact with prodigious speed, will move but sluggishly through the remoter parts of its orbit. In computing the periodic time of the comet of 1811, Lemaur assigned 775 years to the half of the ellipse nearest the sun, and 3462 to the more distant half. But the space must be immense that has to be traversed by an object whose return is not expected, taking the lowest estimate given, till the year 4867. The appearance of this comet was strikingly ornamental to the evening sky. Many a reaper late in the harvest field stayed his hand, and many a peasant homeward-bound stopped in the way, to gaze upon the celestial novelty as it grew into distinctness with the declining day. The Ettrick shepherd has left a memorial of his impressions in the well-known lines : — " Stranger of heaven, I bid thee hail ! Shred from the pall of glory riven, That flashest in celestial gale — Broad pennon of the King of Heaven ! " Whate'er portends thy front of fire, And streaming locks so lovely pale : Or peace to man, or jiulgments dire, Stranger of heaven, I bid thee hail ! " Those who were alive in 1811 will recollect the high temperature of that year — its bountiful harvest — its abundant vintage. Popular opinion assigned these blessings to the resplendent comet ; and the wine of the comet was sold afterwards at high prices. No doubt, however, but that precisely different circumstances would have been connected, COMETS. 121 by the public mind, with the same cause ; and this has literally been the case, for " a cold winter," and " meteors in Germany," are referred to the comet of 1680, by a writer in 1829. The following table, given by Arago, is valuable upon this point : — Years. Mean Temperature. Number of Comets. Years. Mean Temperature. Number of Comets. Reaumur. Fahrenheit. Reaumur. Fahrenheit. 1803 10-6° 56° 0 1818 11-4° 58° o 1804 II -1 57 1 1819 11-1 57 3 1805 9-7 54 2 1820 98 54 0 1806 121 59 1 1821 11-1 57 1 1807 10-8 56 1 1822 12-1 59 3 1808 10-4 55 4 1823 10-4 55 1 1809 10-6 56 0 1824 11-2 57 2 1810 1O-6 56 1 1825 11-7 58 4 1811 12-0 59 2 1826 11 4 58 5 1812 9-9 56 1 1827 10-8 56 3 1813 10^ 55 2 1828 11-5 58 0 1814 9-8 54 0 1829 9-1 53 1 181.5 10-5 56 1 1830 10-1 55 2 . 181G 9-4 53 0 1831 11-7 53 0 1817 10-4 55 O From this table, it is clear that no conclusion can be drawn, to the effect that cometary appearances have any influence in raising the temperature. In 1828 and in 1831 no comets presented themselves, and the temperature was nearly at its maximum. In 1808 there were four, and it was nearly at its minimum. There was no inconsiderable amount of superstitious fear blended upon this occasion with the natural feelings of wonder and admiration that were excited. As the great comet of 1680 had been deemed a manifest presage of the revocation of the edict of Nantes, the persecution of the French protestants, and the long wars that ensued, so was the beautiful and transient visitor of 1811 abused in a similar manner. It was widely regarded as the herald of some awful terrestrial occurrence, and the particular event intended was not 122 SCENERY OF THE HEAVENS. doubtful to many minds when Napoleon led his legions from the West to perish amid the snows of Russia, and Moscow was in flames ! Science has been more recently occupied with comets of short periods, insignificant in their external aspect, but deeply interesting on account of the discovery that their orbital course is included within the bounds of our system, and their predicted returns fulfilled with unfailing punctuality. The first is known as the comet of Encke. It was observed in the year 1786, by Messier, traversing the constellation Aquarius ; afterwards seen by Miss Herschel, in 1795, in Cyg- nus; and byM.Pons, in 1805, in Ursa Major ; but no idea was entertained that these were appearances of the same body, till Encke, in 1819, established their identity, in consequence of which the comet has received his name. It passes at its perihelion within the orbit of Mer cury, and has its aphelion midway be tween the paths of the telescopic planets and Jupiter, its greatest distance from the sun being twelve times its least dis tance, and its period of revolution 1203 days or 3^0- years. This object has now frequently answered to the announce ments made respecting its course, incontestably establishing its character as n regular member of our system, moving in obedience to its laws. The comet appears as a small globular patch of vapour, without any starlike nucleus or tail, scarcely perceptible, and its dimness seems to be increasing. But this insignificant and shadowy thing exhibits a deeply interesting and important phenomenon, that of the gradual diminution of its periodic time, owing to a decrease in the size of its orbit, the supposed effect of a resisting medium in space, which is urging it nearer the sun, and may ultimately terminate its career as a separate body. The same conclusion is entertained with reference to the planets, founded upon this peculiarity of the comet of Encke. If the spaces in which they move is occupied by a resisting medium, that, it is conceived, will, in the long run of ages, diminish their actual velocity, decrease the centrifugal force, give more power to the solar attraction, draw them towards the centre, and thus end the system. Such a speculation is, to say the least, premature. We may admit the existence of an etherial medium which shall perceptibly affect the movements of a small vapoury globule, yet offer no appreciable opposition to the solid and weighty planetary masses. The proper course is to wait until such a medium is placed beyond all doubt, for it cannot be said yet to be de monstrated ; and until we have some evidence of its action in the case of the planets, before we reason upon it as a fact. Besides the comet of Encke there is another whose periodicity has been ascertained, a discovery due to M. Biela, in 1826. This object is also without tail or nucleus, and scarcely visible to the naked eye. Its aphelion place is a little beyond the orbit of Jupiter, its perihelion within that of Venus, its time of revolution 2461 days, or 6| years. This was the comet which excited a large amount of apprehension for the safety of our terrestrial mansion, prior to its return in 1832. It was calculated that a little before midnight, on the 29th of October, it would cross the plane in which the earth revolves, near the point where our globe itself would be on the morning of the 30th of November following ; and, undoubtedly, had the comet been delayed a month by any disturbance, a collision with its nebulosity would have taken place. The alarm was COMETS. 123 principally confined to the Parisians, who seem to be somewhat addicted to such fears. In the year 1773, in consequence of some rumour getting afloat concerning an expected comet, the public tranquillity was completely disturbed, and Lalande was requested by the civil authorities to interfere to assuage the popular terrors. To prevent their renewal in 1832 the authority of the Academy of Sciences was invoked in relation to the anticipated visitor, and Arago wrote a celebrated treatise to show the groundlessness of all alarm. Accordingly, the earth's progress in its orbit being at the mean rate of two millions of miles daily, and a month intervening between the passage of the comet across it and the arrival of the earth at the same point, the two bodies were never nearer than sixty millions of miles. The accompanying dia gram represents its course as compared with that of the earth. On the ellipse are marked its places for the beginning of each year, from 1833 to 1840. There are 13 elliptic comets now known revolving within the orbit of Saturn ; 7 whose mean distances are nearly equal to that of Uranus; and 21 of long period which pass beyond the limits of the solar system. In the spring of 1843 the world was sud denly startled by the apparition of an object in the western heavens, soon after sunset, like a streak of aurora, streaming from the region of the sun below the constellation Orion. Its outline was so distinct, and its light so conspicuous, as immediately to arrest the attention of persons abroad upon the roads, and in vessels at sea. By many observers it was mistaken at first for the zodiacal light ; but its aspect and movements proved it to be a comet of the very largest class. The nucleus was not seen here, but it was visible in more southern latitudes, where the whole appearance of the comet was far more definite than with us. The phenomenon was observed on board the Tay on her homeward voyage from the West Indies, upon the 6th of March ; at Nice on the 12th, by our countryman, Mr. Cooper; at Oporto on the 14th; and at Paris on the 17th. On Sunday evening, soon after seven o'clock, Mr. Cooper had his attention called by his servant to a white line of light near the western horizon. It was like a narrow thin cloud (cirro-stratus), one end being apparently merged in the remaining solar light, and the other in or near the constellation Lepus. On the 13th, at the same hour, the light re-appeared in a direction parallel to the line joining rj Leporis with y Eridani. On the 14th, having prepared his comet-seeker, he found the nucleus by sweeping down the line of light, which appeared stellar about the sixth magnitude. The proportion of the tail actually visible here on the nights of the 17th and 18th was fully 30° in length according to Sir John Herschel, and after ward 45° were measurable by Sir James South. Instead of being luminous at the edges, and more obscure in the middle, a general characteristic of cometary tails, which has induced the belief that they are cones internally empty, the light of the tail, in the present instance, was visibly more intense in the centre than on the sides. 124 SCENERY OF THE HEAVENS. This was one of the largest comets ever observed, and would have appeared an extra ordinary object if circumstances had been favourable to its exhibition to us. Its train must have extended through celestial space to the enormous length of a hundred and sixty millions of miles. It was travelling with prodigious velocity away from the sun, having doubled the solar orb upon first becoming visible, and soon vanished from terrestrial gaze in the immensities of the universe. In South Africa its appear ance was very distinct. Mr Maclear, at the observatory in the neighbourhood of Cape Town, states : — " Of the casual observatory phenomena, the grand comet of March takes precedence ; and few of its kind have been so splendid and imposing. I remember that of 1811 : it was not half so brilliant as the late one. Immersed in the ravines of the Cedar-berg, with high and precipitous ranges on each side of me, I made stre nuous efforts to reach the Snew-berg station, to command a view of the sudden visitor. Those unacquainted with the character of the Cedar-berg cannot form a conception of the difficulties I had to encounter. For seventeen days we toiled on, tantalised every evening by seeing a portion of the tail over the mountain tops, and sometimes a sight of its bright head, as openings in the mountains permitted." This comet, as observed at Washington, is thus described by Lieutenant Maury, in a communication from the Hydrographical Office in that city: — "On Monday morning, March 6, our attention was called to a paragraph in the newspapers, stating that a comet was visible near the sun at mid-day with the naked eye. The sky was clear ; but, not being able to discover any thing with the unassisted eye, recourse was had to a telescope, without any better success. About sunset in the evening the examination was renewed with great diligence, but to no purpose. The last faint streak of day gilded the west, beautiful and delicate fleeces of cloud curtained the bed of the sun, the upper sky was studded with stars, and all hopes of seeing the comet that evening had vanished. Soon after we had retired, the officer of the watch announced the appearance of the comet in the west. The phenomenon was sublime and beautiful. The needle was greatly agitated ; and a strongly marked pencil of light was streaming up from the path of the sun in an oblique direction to the southward and eastward ; its edges were parallel. It was 1° 30' broad, and 30° long. Stars could be seen twinkling through it, and no doubt was at first entertained but that this was the tail of the comet. The officer of the watch was directed to search the eastern sky with the telescope in the morning, from early dawn and before, till sunrise. Nothing strange or uncommon was noted by him. Tuesday was a beautiful day. The sun was clear, gilding, as it sunk below the hills, a narrow streak of cloud, seen through the tree-tops beyond the Potomac. The tail had appeared of great length for the first time the evening before ; therefore we expected to find its length this evening greatly increased. It was a moment of intense interest when the first stars began to appear. The last rays of the sun still lingered on the horizon, and at this moment a well defined pencil of hairy light was seen pointing towards the sun. At 5 h. 41 m. sidereal time, the first measurement of length of the tail was taken ; it measured 41° to the horizon. At 6h. 19 m. it had become most distinct. It was then 1° 45' broad, and 55° long, not including the part below the horizon, which, supposing its terminus to be near the sun, could not, owing to the oblique angle which it made with the horizon, be less than 10° or 15° more. It now commenced gradually to fade away, and in a short time had entirely disappeared. The morning observations were diligently renewed, but nothing could be seen worthy of note." A letter dated March 22d from Constantinople records the advent of the visitor in that region, and the various speculations of its mongrel population concerning it : — " The attention of the public has been called from terrestrial to celestial matters within the last week, by the appearance of a luminous body in the southern hemisphere, by some declared to be a comet of extraordinary magnitude, by others a COMETS. 125 meteoric or nebulous coruscation. It becomes visible about seven o'clock, p. M., and remains in sight for about two hours. Its position is nearly S.S.W., and its magnitude, measured by the sextant, is 1° in breadth and 21° in length, with a dip of 45°. The appearance of this phenomenon has excited general interest among the natives. The mounejimbashy (chief astrologer) declares that it prognosticates great disasters to people residing southwards ; it forebodes, in the first place, divers calamities to Greece ; and. secondly, a termination of French Razias in Algiers. On the other hand, the Greek priests, with no other instruments than their spectacles, announce that they read in its luminous tail the restoration of the profligate Greek empire, and the downfal of modern rule in Europe. Then, again, the Persian muchats at the Valide Khan all stroke their beards, and swear by the twelve Imans that the meteor represents the flaming death-bladed sword of Ali uplifted to wreak vengeance upon the heretic followers of Omer, for the outrages recently committed upon the sainted tombs of Kerbebah. In the meanwhile, as there are neither astronomers nor instruments at this place, nothing is left for us but to await accounts from Europe, in order to determine the real nature of this extraordinary and splendid phenomenon." A European, travelling in the wilds of America, the only representative of the civilised world present upon the occasion, has graphically narrated his own impressions, and those of his Indian companions : — "We were ascending the Essequibo, that noble river which, though a small rill among the mountains of the equator, disembogues its accumulated waters through three channels nearly twenty miles wide. The weather was unfavourable ; torrents of rain had descended, and the sky had been covered with clouds for weeks. We were approaching the cataract Ouropocari in 4° 11' north latitude, and had encamped, on the 8th of March, three miles below it, when, for the first time since our departure from the coast, the sky, hitherto a uniform mass of greyish clouds, cleared in the evening, and exposed, towards the south-west, the deep tropical blue, spangled with stars. We hailed with pleasure the prediction of better weather ; but what was our amazement when we observed, in the W.S.AV., a broad, white, nebulous band, inclining towards the horizon, and stretching to an altitude of 45° ! The zenith was covered with those beautiful clouds which the meteorologist calls cirro-cumulus ; the sky was, however, perfectly clear on both sides of the band which, 64' (in arc) broad, and of a pure white, almost transparent, formed a strong contrast Ifrith the deep azure of the tropical sky. I could not observe whether the band rested apparently on the horizon, as the wall-like forest, near the edge of which we were encamped, prevented me from seeing that portion of the sky. From the point where the band became visible it appeared of a uniform breadth, becoming more transparent, and slightly diverging, near the summit. What can it be ? was the first question. My Indian friends stood around, looking now with wonder at the phenomenon, now askance at me. Our doubts were solved next evening, March 9 : it was a comet ! Our camp was so favourably situated that the south-western horizon was exposed to our view. The sky was partially clouded until seven o'clock, when the clouds to the west cleared away, and there stood the comet in all its grandeur, the nucleus being about 12° above the horizon, and the tail extending to the star v Eridani, then about 45° high. The nucleus appeared, to the naked eye, like a star of the second magnitude ; its tail, near the base like a narrow band, spread in its broadest part 1° 10', and lost itself in the constellation Eridanus. The whitish light and transparent vapour of its tail, resembling more those clouds compared to ' The beauteous semblance of a flock at rest,' diverged about 20° below the foot of Orion, in nebulous stripes. We stood amazed. A bright moon somewhat lessened the effect which this most wonderful of all natural phenomena would have produced had all else been hidden in darkness ; but the extent of 126 SCENERY OF THE HEAVENS. the tail rendered it remarkable ; indeed, it was the largest which we, who stood assembled, had ever witnessed in our lifetime. I still recollect the beautiful comet of 1811, with its diverging beams of fiery hue, but its tail was much less in length than the one now looked upon. It was a scene which has fixed itself firmly upon my memory. There we stood, upon a small island in the middle of the Essequibo, surrounded by foaming waters which, opposed in their course by dykes of granite, went thundering away over the black stony masses, — I the only European among a number of naked savages, the coppery tint of whose bodies shone in strong contrast when the burning embers of the camp fires threw a ray upon their figures ; some standing upright, with their arms across their breast, others squatting on the ground, but their fearful eyes all directed towards the strange star with its luminous train. No word was spoken. The rush of the foaming waters was the only interruption of the silence. Tamanua, a young Wapisiana, of more intelligence than is generally met with among his tribe, at last broke silence : ' This is the Spirit of the stars, the dreadful Capishi — famine and pestilence await us ;' and, as if they had only wanted the utterance of a syllable to give vent to their feelings, the assembled Indians burst into a torrent of declamation, lamenting the appearance of the dreaded Capishi, as the precursor of pestilence and famine, and raising, with violent gesticulations, their arms towards the comet. I was surprised to find among my Indian followers the same superstitious dread of a comet which, in all ages, rendered their celestial appearance the terror of the uninstructed and vulgar. The Indians around me consisted of Arecuna ; "Wapisianas, and Macusis. The first called the comet Wataima, signifying, like Capishi, the Spirit of the stars. The Macusi Indians named it Ca-poeseima, ' a fiery cloud,' or Woe-inopsa, ' a sun casting its light behind.' Must we not acknowledge that these simple children of Nature have given to this magnificent phenomenon a more expressive name than we civilised nations ? " This comet is remarkable on various accounts. It advanced nearer to the solar surface than any other on record. That of 1680 approached the sun within one-third of his diameter; but that of 1843 came within one-seventh, and was consequently more than COMETS. 127 twice as near, exposed to a heat of proportionate greater intensity. Sir John Herschel computed that the heat received by its surface during the passage of the perihelion was equal to that which would be received by an equal portion of the earth's surface, if it were exposed to the influence of 47,000 suns, placed at the common distance of the actual sun. It is difficult to conceive how a flimsy body could have resisted such a temperature so as not to have been entirely dissipated. This comet is also remarkable as one of the few on record which have been visible in broad daylight. Comets have been observed to undergo remarkable transformations on their approach to the perihelion, breaking up into two or more separate parts, evidently owing to the action of the sun. Seneca reports an instance of dissolution of this kind ; Hevelius witnessed another ; and Biela's comet exhibited the strange phenomenon on the occasion of its third re-appearance, in the year 1846. It then separated into two distinct comets, which moved side by side, in distinct and independent orbits, as long as visible. One of these objects was a little fainter than the other, but both had tails, and exhibited the distinctive features of a comet. The change of constitution seems to have taken place very suddenly. It was first observed in Europe on the 15th of January, by Mr Challis of Cambridge, and M. Wickmann of Konigsberg ; but it was afterwards found to have been seen on the 1 2th by Lieutenant Maury, at the Observatory of Washington, in the United States. The separation has probably been permanent, and become more decided. In 1852, on the occasion of the fourth re-appearance, Biela's comet was preceded by another, a fainter object, which may have been the companion separated from it, removed to a greater distance. The annexed cut represents some of the various appearances presented by Hallcy's comet in 1835 in different parts of its orbit — a, b, c, in approaching the sun ; d, e, in retreating. It is probable that a great comet, revolving round the sun in the long period of nearly three centuries, was observed in the years 975, 1264, and 1556. This is the opinion of Gauss of Gottingen, Mr Hind, and other astronomers. Assuming the comets of those years to be three apparitions of the same body, its return to the sun may be anticipated after the lapse of a corresponding interval. The wanderer is now overdue, as full three centuries have elapsed since the last period ; but as its time of revolution may be lengthened by planetary perturbations, it will be looked for till the year 1860. In 1264, the comet was visible many months, and very conspicuous. All Europe regarded it as intimating the death of Pope Urban IV. "Its apparition," says Thierri, "boded his illness, and its disappearance his death, as events have proved." Historians relate that it was last seen on the night of the pontiffs decease. In 1556, the comet was also a striking object, and similarly interpreted as signifying terrestrial changes. It was noticed that " the tail was always at first turned towards Spain." The emperor Charles V. was greatly alarmed at its appearance ; and looked upon it as a sign of his approaching death. He is said to have been induced by the impression to cede the imperial crown to his son. The leading features of the chief cometary appearances of modern times have now been sketched. There are various inquiries which naturally suggest themselves with reference to these bodies. What is their physical constitution ] What their origin and office in 128 SCENERY OF THE HEAVENS. the system ? Are they inherently luminous, or dependent upon the solar glory, shining like the planets by virtue of his light ? Have they any terrestrial influence ? Is there a chance of our globe coming into actual collision with them; and supposing collision, what would be its probable effects ? Upon most of these points we have no certain knowledge. Herschel and Schroeter thought the comet of 1811 a self-luminous body, but in opposition to this opinion Cassini is quoted as having descried the comet of 174-i showing a phase. On the very day, says Arago, that any comet shall appear with a distinct phase, all doubts will have ceased. At present however no satisfactory evidence is possessed of such an appearance being observed. Upon the question of physical constitution, it is pretty certain that the great majority of these bodies, and most probably all of them, are entirely gaseous — simple aggregations of vapour. The evidence to this effect is various. The comet of 1770 passed twice through the system of Jupiter; and calculation shows, that had it been -^ of one of the satellites in mass, it would have sensibly affected that system. Yet there was not the slightest derangement of the planes of motion, or of the periods of revolution, by its intrusion among the satellites. The same body also passed at that time at no very great distance from the earth. In fact it approached us nearer than any other that has visited our terrestrial sky. Had it possessed a quantity of solid matter equal to that of the earth, it would then have shortened the length of our year by one ninth of a day ; or had it been ^Vo" of the earth in mass, it would have appreciably altered its length to a degree that must long ago have been observed. But not the least perturbation was caused by its close proximity. These are sufficient proofs of the smallness of its mass, even allowing it to have had any solid matter at all, which may be reasonably suspected. Through the very centre of Biela's comet in 1832 a group of stars of the sixteenth magnitude was very distinctly seen by Sir John Herschel. While admitting that many comets are mere agglomerations of vapour, some hold to the opinion that where there is a nucleus remarkable for its vivacity of light, there is a solid and opaque body. But several facts declare against this supposition. Instances have occurred of stars being visible through a strongly defined nucleus. In 1618, the nucleus of the comet of that year is described as having dissolved into several detached parts ; that of 1661 observed by Hevelius, changed also from a globular figure, and entirely disappeared; and the most extraordinary transformations are suddenly effected in the constitution of these objects. It is most probable that a comet is altogether a gaseous body, and has no solid matter whatever. Sir John Herschel remarks, that " whenever powerful telescopes have been turned on them, they have not failed to dispel the illusion which attributes solidity to that more condensed part of the head, which appears to the naked eye as a nucleus ; though it is true that in some a very minute stellar point has been seen, indicating the existence of a solid body." Mr. Airy also states, that " on the physical constitution of comets we have learnt nothing, except that they appear to be wholly gaseous." These views of the constitution of cometary bodies show the fallacy of apprehending those consequences from a shock with them, of which terrific pictures have been drawn, and the impossibility of those events being produced by collision, which have been assigned to it, such as the deluge of Noah, the depression of the Caspian Sea and its neighbourhood, with the formation of the small telescopic planets out of a comet-stricken orb. " It is easy to represent," says Laplace, " the effect of such a shock upon the earth ; the axis and motion of rotation changed ; the waters abandoning their ancient position to precipitate themselves towards the new equator ; the greater part of men and animals drowned in a universal deluge, or destroyed by the violence of the shock given to the terrestrial globe ; whole species annihilated ; all the monuments of human industry reversed ; such are the disasters which a shock of a comet would produce. "We see then," he observes, referring COMETS. 129 to this cause some singular facts in geology, explained, " why the ocean has abandoned the highest mountains, on which it has left incontestable marks of its former abode. "We see why the animals and plants of the south may have existed in the climates of the north, where their relics and impressions are still to be found. Lastly, it explains the short period of the existence of the moral world, whose earliest monuments do not go much further back than three thousand years. The human race, reduced to a small number of individuals, in the most deplorable state, occupied only with the immediate care for their subsistence, must necessarily have lost the remembrance of all sciences and of every art ; and when the progress of civilisation has again created new wants, everything was to be done again, as if mankind had been just placed upon the earth." When this was the language of a philosopher of such high repute, the cockneys and belles of Paris might well tremble at the announcement of a comet. " Popular terrors," said a professor there upon a recent occasion, " are productive of serious consequences. Several members of the Academy may still remember the accidents and disorders which followed a similar threat, impru dently communicated to the Academy by M. Delande in May 1773. Persons of weak minds died of fright, and women miscarried. There were not wanting people, who knew too well the art of turning to their advantage the alarm inspired by the apprehended comet, and places in Paradise were sold at very high prices. The announcement of the comet of 1832 may produce similar effects, unless the authority of the Academy apply a prompt remedy ; and this salutary intervention is at this moment implored by many benevolent persons." The possibility of collision with one of these vagrant cruisers in space may indeed be soberly entertained, as they move in all imaginable directions, penetrate within the interior of the planetary orbits, and often pass between Mercury and the sun. But a calculation of probabilities shows, that of 281,000,000 of chances, there are 280,999,999 that are favourable to one unfavourable. The probability, therefore, of such an event happening in the experience of any individual of the human race is no greater than it would be with reference to his drawing one black ball, supposing it in an urn with 280,999,999 white balls. As to the near approach of a comet producing any great terrestrial change, such as deflecting our globe from its orbit by attraction, and scampering off with it as a satellite, we have plain warrant to treat the assumption as romance. The case of Lexel's lost comet intruding in the system of Jupiter without disturbing it, but being itself twisted into a new path, may lead us to allow of some approach to fellowship with perfect safety. That comet advanced to within six times the distance of the moon from us, yet it neither raised our tides a jot, nor added a single second to our year, though the diameter of its head was estimated to be thirteen times that of our satellite. We, indeed, were not quite so passive upon that occasion, for the action of the earth upon the comet increased the time of its revolution by two days. Even should an instance of actual contact occur, there seems no more reason to infer physical convulsion from the attack of a gaseous body, than in the case of a squadron of clouds assailing the sides and summit of a mountain. In all probability the only effect would be a change of temperature, with some peculiar atmospheric phenomena, yet compatible with a full security to human life and happiness. That the orbital course and rotation of our planet would be affected ; that the pole and the equator would exchange places ; that the ocean would leave its present bed, and the dry land be submerged ; that any consequence would follow beyond a temporary alteration of climate, we have not only no authority to suppose, but strong grounds to deny. The surmise has been entertained that, in the year 1837, our globe experienced some cometary entanglement ; and nothing more likely than that repeatedly, since the Creation, the terrestrial surface has received a brush. No trifling service has been rendered to mankind by science, that now these bodies are divested of those attributes of 130 SCENERY OP THE HEAVENS. terror with which they were identified in ages past, when regarded as the heralds of political misfortune, or portending fatal physical events. "When tidings came across the seas, brought by merchant and monk, that William the Norman was preparing to contest the possession of his territories with Harold, a comet, flaring in the heavens, raised misgivings in the Saxon mind as to the issue of the event, and unnerved him for the struggle when all his vigour was most required. An after chronicle relates how a star with three long tails appeared in the sky, how the learned declared that such stars appeared only when a kingdom wanted a new king, and how the said star was called a " comette." So, in 1618, a similar object was believed, in France, to foreshow another Bartholomew massacre ; in Holland, to predict the death of Barneveldt ; at Vienna its fiery aspect was viewed as symbolic of destruction to the Bohemian heretics ; while, in England, it was connected with coming wars, and the death of James's queen. It is no slight advantage to the moderns, that they can gaze upon such objects without antici pating disaster, and regard them as controlled by those laws to which their own world is obedient. CHAPTER VI. AEROLITES. ROM every region of the globe, and in all ages of time within the range of history, exhibitions of apparent instability in the heavens have been observed, when the curtains of the evening have been drawn. Suddenly, a line of light arrests the eye, darting like an arrow through a vaiying extent of space, and in a moment the firmament is as sombre as before. The appearance is exactly that of a star falling from its sphere, and hence the popular title of shooting star applied to it. The apparent magnitudes of these meteorites are widely different, and also their brilliancy. Occasionally, they are far more resplendent than the brightest of the planets, and throw a very perceptible illumination upon the path of the observer. A second or two commonly sufiices for the individual display, but in some instances it has lasted several minutes. In every climate it is witnessed, and at all times of the year, but most frequently in the autumnal months. As far back as records go, we meet with allusions to these swift and evanescent luminous travellers. Minerva's hasty flight from the peaks of Olympus to break the truce between the Greeks and Trojans, is compared by Homer to the emission of a brilliant star. Virgil, in the first book of the Georgics, mentions the shooting stars as prognosticating weather changes : — " And oft, before tempestuous winds arise, The seeming stars fall headlong from the skies, And, shooting through the darkness, gild the night With sweeping glories and long trains of light." Various hypotheses have been framed to explain the nature and origin of these remark able appearances. When electricity began to be understood, this was thought to afford a satisfactory explanation, and the shooting stars were regarded by Beccaria and Vassali as merely electrical sparks. When the inflammable nature of the gases became known, Lavoisier and Volta supposed an accumulation of hydrogen in the higher regions of the atmosphere, because of its inferior density, giving rise by ignition to the meteoric AEROLITES. 131 exhibitions. While these theories of the older philosophers have been shown to be untenable, there is still great obscurity resting upon the question, though we have reason to refer the phenomena to a cause exterior to the bounds of our atmosphere. Upon this ground, the subject assumes a strictly astronomical aspect, and claims a place in a treatise on the economy of the solar system. The first attempt accurately to investigate these elegant meteors was made by two university students, afterwards Professors Brandes of Leipsic, and Benzenberg of Dussel- dorf, in the year 1798. They selected a base line of 46,200 feet, somewhat less than nine English miles, and placed themselves at its extremities on appointed nights, for the pur pose of ascertaining their average altitude and velocity. Out of twenty-two appearances identified as the same, they found 7 under 45 miles 9 between 45 and 90 miles 5 above 90 miles 1 above 140 — The greatest observed velocity gave twenty-five miles in a second. A more extensive plan was organised by Brandes in the year 1823, and carried into effect in the neighbour hood of Breslau. Out of ninety-eight appearances, the computed heights were, 4 under 1 5 miles 15 from 15 to 30 miles 22 — 30 to 45 — 33 — 45 to 70 — 13 from 70 to 90 miles 6 above 90 miles 5 from 140 to 460 miles. The velocities were between eighteen and thirty-six miles in a second, an average velo city far greater than that of the earth in its orbit. - The rush of luminous bodies through the sky of a more extraordinary kind, though a rare occurrence, has repeatedly been observed. They are usually discriminated from shooting stars, and known by the vulgar as fire-balls ; but probably both proceed from the same cause, and are identical phenomena. They have sometimes been seen of large volume, giving an intense light, a hissing noise accompanying their progress, and a loud explosion attending their termination. In the year 1676, a meteor passed over Italy about two hours after sunset, upon which Montanari wrote a treatise. It came over the Adriatic Sea as if from Dalmatia, crossed the country in the direction of Rimini and Leghorn, a loud report being heard at the latter place, and disappeared upon the sea to wards Corsica. A similar visitor was witnessed all over England in 1718, and forms the sub- jectof oneof Halley's papers to the Royal Society. Sir Hans Sloane was one of its spectators. Being abroad at the time of its appearance, at a quarter past eight at night, in the streets of London, his path was suddenly and intensely illuminated. This, he apprehended at first, might arise from a discharge of rockets ; but found a fiery object in the heavens, moving after the manner of a falling star, in a direct line from the Pleiades to below the girdle of Orion. Its brightness was so vivid, that several times he was obliged to turn away his eyes from it. The stars disappeared, and the moon, then nine days old, and high near the meridian, the sky being very clear, was so effaced by the lustre of the meteor as to be scarcely seen. It was computed to have passed over three hundred geo graphical miles in a minute, at the distance of sixty miles above the surface, and was observed at different extremities of the kingdom. The sound of an explosion was heard through Devon and Cornwall, and along the opposite coast of Bretagne. Halley con jectured this and similar displays to proceed from combustible vapours aggregated on the outskirts of the atmosphere, and suddenly set on fire by some unknown cause. But since his time, the fact has been established, of the actual fall of heavy bodies to the earth from surrounding space, which requires another hypothesis. To these bodies the term aerolites is applied, signifying atmospheric stones, from a?)p, the atmosphere, and X/0oe, a stone. 132 SCENERY OF THE HEAVENS. While many meteoric appearances may simply arise from electricity, or from the inflam mable gases, it is now certain, from the proved descent of aerolites, that such bodies are of extra-terrestrial origin. Antiquity refers us to several objects as having descended from the skies, the gifts of the immortal gods. Such was the Palladium of Troy, the image of the goddess of Ephesus, and the sacred shield of Numa. The folly of the ancients in believing such narrations has often been the subject of remark ; but, however fabulous the particular cases referred to, the moderns have been compelled to renounce their scepticism respecting the fact itself, of the actual transition of substances from celestial space to terrestrial regions ; and no doubt the ancient faith upon this subject was founded on observed events. The following table, taken from the work of M. Izarn, Des Picrres tombees du Ciel, ex hibits a collection of instances of the fall of aerolites, together with the eras of their descent, and the persons on whose evidence the facts rest ; but the list might be largely extended. Substance. Place. Period. Authority. Shower of stones At Rome Under Tullus Hostilius Livy. Shower of stones At Rome Consuls C. Martius and M. Tor. J. Obsequens. qualus Shower of iron In Lucania Year before the defeat of Crassus Pliny. Shower of mercury In Italy .... Dion. Large stone Near the river Negos, Thrace Second year of the 78th Olym Pliny. piad Three large stones In Thrace Year before J. C. 452 Ch. of Count Marcellin. Shower of fire At Quesnoy January 4. 1717 Geoffroy le Cadet. Stone of 72 Ibs. Near Larissa, Macedonia January, 1706 Paul Lucas. About 1 200 stones— one of 120 Ibs. ) Another of 60 Ibs. 3 Near Padua, in Italy In 1510 Carden, Varcit. Another of 59 Ibs. On Mount Vasier, Provence November 27. 1627 Gassendi. Shower of sand for 15 hours In the Atlantic Aprils. 1719. PSre la Fuillee. Shower of sulphur Sodom and Gomorra * . Moses. Sulphurous rain The same In the Duchy of Mansfield Copenhagen In 1658 In 1646 Spangenbiirgh. Olaus Worm i us. Shower of sulphur Brunswick October, 1721 Siegesbser. Shower of unknown matter Ireland In 1695 Muschcnbroeck. Two large stones, weighing 20 Ibs. Liponas, in Bresso September, 1753 Lalande. A stony mass Niort, Normandy In 1750 Lalande. A stone of 7J Ibs. A stone At Luce, in Le Maine At Aire, in Artois September 13. 1768 | Bachelay. In 1768 Gursoime de Boyaval. A stone In Le Cotentin In 1768 Morand. Extensive shower of stones Environs of Agen July 24. 1790 St. Amand, Baudin, &c. About twelve stones Sienna, Tuscany July, 1794 Karl of Bristol. A large stone of 56 Ibs. Wold Cottage, Yorkshire December 13. 1795 Captain Topham. A stone of about 20 Ibs. Sale, Department of the Rhone March 17, 1798 Lelievre and De Dree. A stone of 10 Ibs. In Portugal February 19. 1796 Southey. Shower of stones Benares, East Indies December 19. 1798 J. Lloyd Williams, Esq. Shower of stones At Plaun, near Tabor, Bohemia July 3. 1753 IJ. de Born. Mass of iron, 70 cubic feet America April 5. 1800 Philosophical Mag. Mass of iron, 14 quintals Abakauk, Siberia Very old Pallas, Chladni, &c. Shower of stones Barboutan, near Roquefort July, 1789 Darcet.Jun., Lomet,&c. Large stone of 260 Ibs. Two stones, 200 and 300 Ibs. Ensisheim, Upper Rhine Near Verona November 7. 1492 In 1762 Butenschoen. Acad. de Bourd. A stone of 20 Ibs. Sules, near Ville Tranche March 12. 1798 De Dree. Several stones from 10 to 17 Ibs. Near L'Aigle, Normandy April 26. 1803 Fourcroy. Some of the instances in the table are of sufficient interest to deserve a notice. A singular relation respecting the stone of Ensisheim on the Rhine, at which philosophy once smiled incredulously, regarding it as one of the romances of the middle ages, may now be admitted to sober attention as a piece of authentic history. A homely narrative of its fall was drawn up at the time by order of the emperor Maximilian, and deposited with the stone in the church. It may thus be rendered : — "In the year of the Lord 1492, on Wednesday, which was Martinmas eve, the 7th of November, a singular miracle oc curred ; for, between eleven o'clock and noon, there was a loud clap of thunder, and a prolonged confused noise, which was heard at a great distance ; and a stone fell from the air, in the jurisdiction of Ensisheim, which weighed two hundred and sixty pounds, and the confused noise was, besides, much louder than here. Then a child saw it strike on a field in the upper jurisdiction, towards the Rhine and Inn, near the district of Giscano, AEROLITES. 133 which was sown with wheat, and it did it no harm, except that it made a hole there : and then they conveyed it from that spot ; and many pieces were broken from it ; which the landvogt forbade. They, therefore, caused it to be placed in the church, with the inten tion of suspending it as a miracle : and there came here many people to see this stone. So there were remarkable conversations about this stone : but the learned said that they knew not what it was ; for it was beyond the ordinary course of nature that such a large stone should smite the earth from the height of the air ; but that it was really a miracle of God ; for, before that time, never anything was heard like it, nor seen, nor described. When they found that stone, it had entered into the earth to the depth of a man's stature, which everybody explained to be the will of God that it should be found ; and the noise of it was heard at Lucerne, at Vitting, and in many other places, so loud that it was believed that houses had been overturned : and as the King Maximilian was here the Monday after St. Catharine's day of the same year, his royal Excellency ordered the stone which had fallen to be brought to the Castle, and, after having conversed a long time about it with the noblemen, he said that the people of Ensisheim should take it, and order it to be hung up in the church, and not to allow anybody to take anything from it. His Excellency, however, took two pieces of it ; of which he kept one, and sent the other to the Duke Sigismund of Austria : and they spoke a great deal about this stone, which they suspended in the choir, where it still is ; and a great many people came to see it." Con temporary writers confirm the substance of this narration, and the evidence of the fact exists ; the aerolite is precisely identical in its chemical composition with that of other meteoric stones. It remained for three centuries suspended in the church, was carried off to Colmar during the French revolution ; but has since been restored to its former site, and Ensisheim rejoices in the possession of the relic. A piece broken from it is in the museum of the Jardin des Plantes at Paris, and another in the British Museum. The celebrated Gassendi was an eye-witness of a similar event. In the year 1627, on the 27th of November, the sky being quite clear, he saw a burning stone fall in the neighbourhood of Nice, and examined the mass. While in the air it appeared to be about four feet in diameter, was surrounded by a luminous circle of colours like a rainbow, and its fall was accompanied by a noise like the discharge of artillery. Upon inspecting the substance, he found it weighed 591bs., was extremely hard, of a dull metallic colour, and of a specific gravity considerably greater than that of common marble. Having only this solitary instance of such an occurrence, Gassendi concluded that the mass came from some of the mountains of Provence, which had been in a transient state of volcanic activity. Instances of the same phenomenon occurred in the years 1672, 1756, and 1768; but the facts were generally doubted by naturalists, and considered as electrical appear ances magnified by popular ignorance and timidity. A remarkable example took place in France in the year 1790. Between nine and ten o'clock at night, on the 24th of July, a luminous ball was seen traversing the atmosphere with great rapidity, and leaving behind it a train of light ; a loud explosion was then heard, accompanied with sparks which flew off in all directions ; this was followed by a shower of stones over a considerable extent of ground, at various distances from each other, and of different sizes. A proces verbal was drawn up, attesting the circumstance, signed by the magistrates of the municipality, and by several hundreds of persons inhabiting the district. This curious document is literally as follows : — "In the year one thousand seven hundred and ninety, and the thirtieth day of the month of August, we, the Lieut. Jean Duby, mayor, aud Louis Massillon, procu rator of the commune of the municipality of La Grange-de-Juillac, and Jean Darmite, resident in the parish of La Grange-de-Juillac, certify in truth and verity, that on Saturday, the 24th of July last, between nine and ten o'clock, there passed a great fire, and after it we heard in the air a very loud and extraordinary noise ; and about two 134 SCENERY OF THE HEAVENS. minutes after, there fell stones from heaven ; but fortunately there fell only a very few, and they fell about ten paces from one another in some places, and in others nearer, and finally, in some other places farther ; and falling, most of them, of the weight of about half a quarter of a pound each, some others of about half a pound, like that found in our parish of La Grange ; and on the borders of the parish of Creon, they were found of a pound weight ; and in falling, they seemed not to be inflamed, but very hard and black without, and within of the colour of steel : and, thank God, they occasioned no harm to the people, nor to the trees, but only to some tiles which were broken on the houses ; and most of them fell gently, and others fell quickly with a hissing noise ; and some were found which had entered into the earth, but very few. In witness whereof, we have written and signed these presents. Duby, mayor. Darmite." Though such a document as this, coming from the unlearned of the district where the phenomenon occurred, was not cal culated to win acceptance with the savans of the French capital ; yet it was corroborated by a host of intelligent witnesses at Bayonne, Thoulouse, and Bordeaux, and by trans mitted specimens containing the substances usually found in atmospheric stones, and in nearly the same proportions. A few years afterwards, an undoubted instance of the full of an aerolite occurred in our own country, which largely excited public curiosity. This was in the neighbourhood of "Wold Cottage, the house of Captain Topham, in Yorkshire. Several persons heard the report of an explosion in the air, followed by a hissing sound ; and afterwards felt a shock, as if a heavy body had fallen to the ground at a little distance from them. One of these, a ploughman, saw a huge stone falling towards the earth, eight or nine yards from the place where he stood. It threw up the mould on eveiy side, and after penetrating through the soil, lodged some inches deep in solid chalk rock. Upon being raised, the stone was found to weigh fifty-six pounds. It fell in the afternoon of a mild but hazy day, during which there was no thunder or lightning ; and the noise of the explosion was heard through a considerable district. It deserves remark, that in most recorded cases of the descent of projectiles, the weather has been settled and the sky clear ; a fact which plainly places them apart from the causes which operate to produce the tempest, and shows the popular term thunderbolt to be an entire misnomer. While this train of circumstances was preparing the philosophic mind of Europe to admit as a truth what had hitherto been deemed a vulgar error, and acknowledge the ap pearance of masses of ignited matter in the atmosphere occasionally descending to the earth, an account of a phenomenon of this kind was received from India, vouched by an authority calculated to secure it general respect. It came from Mr. Williams, F.R.S., a resident in Bengal. It stated that on December 19th, 1798, at eight o'clock in the evening, a large luminous meteor was seen at Benares and other parts of the country. It was attended with a loud rumbling noise, like an ill-discharged platoon of musketry ; and about the same time, the inhabitants of Krakhut, fourteen miles from Benares, saw the light, heard an explosion, and immediately after the noise of heavy bodies falling in the neighbourhood. The sky had previously been serene, and not the smallest vestige of a cloud had appeared for many days. Next morning, the mould in the fields was found to have been turned up in many spots ; and unusual stones of various sizes, but of the same substance, were picked out from the moist soil, generally from a depth of six inches. As the occurrence took place in the night, after the people had retired to rest, the explosion and the actual fall of the stones were not observed : but the watchman of an English gentleman, near Krakhut, brought him a stone the next morning which had fallen through the top of his hut, and buried itself in the earthen floor. This event in India was fol lowed in the year 1803 by a convincing demonstration in France, which compelled the eminent men of the capital to believe, though much against their will. On Tuesday, April 26th, about one in the afternoon, the weather being serene, there was observed, in AEROLITES. 135 a part of Normandy, including Caen, Falaise, Alencon, and a large number of villages, a fiery globe of great brilliancy moving in the atmosphere with great rapidity. Some moments after, there was heard at L'Aigle and in the environs to the extent of more than thirty leagues in every direction, a violent explosion, which lasted five or six minutes. At first there were three or four reports like those of a cannon, followed by a kind of dis charge which resembled the firing of musketry ; after which there was heard a rumbling like the beating of a drum. The air was calm and the sky serene, except a few clouds, such as are frequently observed. The noise proceeded from a small cloud which had a rectangular form, and appeared motionless all the time that the phenomenon lasted. The vapour of which it was composed was projected in all directions at the successive explosions. The cloud seemed about half a league to the north-east of the town of L'Aigle, and must have been at a great elevation in the atmosphere, for the inhabitants of two hamlets, a league distant from each other, saw it at the same time above their heads. In the whole canton over which it hovered a hissing noise like that of a stone discharged from a sling was heard : and a multitude of mineral masses were seen to fall to the ground. The largest that fell weighed 17^ pounds ; and the gross number amounted to nearly three thousand. By the direction of the Academy of Sciences, all the circum stances of this event were minutely examined by a commission of inquiry with the celebrated M. Biot at its head. They were found in harmony with the preceding relation, and reported to the French minister of the interior. Upon analysing the stones they were found identical with those of Benares. The following are the principal facts with reference to the aerolites, upon which general dependence may be placed. If examined immediately after their descent, they have always a temperature more or less elevated. They are almost invariably invested with a peculiar thin crust, consisting chiefly of oxide of iron, often of pitchy lustre, very distinctly defined from the interior mass. What is most remarkable, in the great majority of cases, their chemical analysis develops the same substances combined in nearly the same proportions, though one may have reached the earth in India, another in England, and a third in the United States. Not more than twenty primary ingredients at the utmost have been noticed in them. But some of the best known consist almost entirely of one ingredient, iron, with a small proportion of nickel. Others contain cobalt, manganese, chromium, copper, tin, arsenic, associated with a small per-centage of oxygen, sulphur, and chlorine. Others consist principally of silica and metallic oxides. It should be distinctly noted, that the iron and nickel are almost always in the metallic form — a state in which they are not found naturally on the surface of the earth. It is also to be observed, that though a chemical examination of their composition has disclosed no substance with which we were not previously acquainted, yet not only are the majority of terrestrial elements wanting, but while non-metallic ingredients occur in the largest quantities in terrestrial nature, they occur in aerolites in much smaller quantities than the metals. Their ingredients are earthly in their kind ; but while many important terrene elements are absent, those that are present are not mingled in earthly proportions. Neither products of our volcanoes, whether active or extinct, nor the stratified or unstratified rocks, exhibit any example of chemical combination similar to that of the meteoric masses. Thus they differ immensely from things terrestrial, as to the number and relative proportion of their constituents. One non-metallic substance alone, oxygen, is computed to form a third of the weight of the crust of the earth ; and oxygen appears feebly in these remarkable objects. During the era that science has admitted the fall of bodies from celestial space scarcely a year has elapsed without a known instance of descent occurring. To Izarn's list, previously given, a great number of examples might be added, which have transpired during the last fifty years. A report relating, to one of the 13G SCENERY OF THE HEAVENS. most recent, which fell in a valley near the Cape of Good Hope, with the affidavits of the witnesses, was communicated to the Royal Society by Sir John Herschel in March ] 840. Previously to the descent of the aerolite, the usual sound of explosion was heard, and Borne of the fragments falling upon grass caused it instantly to smoke, and were too hot to admit of being touched. When, however, we consider the wide range of the ocean, and the vast unoccupied regions of the globe, its mountains, deserts, and forests, we can hardly fail to admit that the observed cases of descent must form but a small proportion of the actual number ; and obviously in countries upon which the human race are thickly planted many may escape notice through descending in the night, and will lie imbedded in the soil till some accidental circumstance exposes their existence. Some too are no doubt com pletely fused and dissipated in the atmosphere, while others move by us horizontally as brilliant lights, and pass into the depths of space. The volume of some of these passing bodies is very great. One which travelled within twenty-five miles of the surface, and cast down a fragment, was supposed to weigh upwards of half a million of tons. But for its great velocity, the whole mass would have been precipitated to the earth. Two aerolites fell at Braunau in Bohemia, July 14, 1847. In addition to aerolites, properly so called, or bodies known to have come to us from outlying space, large metallic masses exist in various parts of the world, lying in insulated situations, far remote from the abodes of civilisation, whose chemical composition is closely analogous to that of the substances the descent of which has been witnessed. These circumstances leave no doubt as to their common origin. Pallas discovered an immense mass of malleable iron, mixed with nickel, at a considerable elevation on a mountain of slate in Siberia, a site plainly irreconcileable with the supposition of art having been there with its forges, even had it possessed the character of the common iron. In one of the rooms of the British Museum there is a specimen of a large mass which was found, and still remains, on the plain of Otumba, in the district of Buenos Ayres. The specimen alone weighs 14001bs., and the weight of the whole mass, which lies half buried in the ground, is computed to be thirteen tons. In the province of Bahia, in Brazil, another block has been discovered weighing upwards of six tons. Considering the situation of these masses, with the details of their chemical analysis, the presumption is clearly warranted that they owe their origin to the same causes that have formed and projected the aerolites to the surface. With reference to the Siberian iron a general tradition prevails among the Tartars that it formerly descended from the heavens. A curious extract, translated from the Emperor Tchangire's memoirs of his own reign is given in a paper communicated to the Royal Society, which speaks of the fall of a metallic mass in India. The prince relates, that in the year 1620 (of our era) a violent explosion was heard at a village in the Punjaub, and at the same time a luminous body fell through the air on the earth. The officer of the district immediately repaired to the spot where it was said the body fell, and having found the place to be still hot, he caused it to be dug. He found that the heat kept increasing till they reached a lump of iron violently hot. This was afterwards sent to court, where the Emperor had it weighed in his presence, and ordered it to be forged into a sabre, a knife, and a dagger. After a trial the workmen reported that it was not malleable, but shivered under the hammer ; and it required to be mixed with one third part of common iron, after which the mass was found to make excellent blades. The royal historian adds, that on the incident of this iron of lightning being manufactured, a poet presented him with a distich that, " during his reign the earth attained order and regularity ; that raw iron fell from lightning, which was, by his world-subduing authority, converted into a dagger, a knife, and two sabres." A multitude of theories have been devised to account for the origin of these remarkable AEROLITES. 137 bodies. The idea is completely inadmissible that they are concretions formed within the limits of the atmosphere. The ingredients that enter into their composition have never been discovered in it, and the air has been analysed at the sea level and on the tops of high mountains. Even supposing that to have been the case, the enormous volume of atmospheric air so charged required to furnish the particles of a mass of several tons, not to say many masses, is, alone, sufficient to refute the notion. They cannot, either, be projectiles from terrestrial volcanoes, because coincident volcanic activity has not been observed, and aerolites descend thousands of miles apart from the nearest volcano, and their substances are discordant with any known volcanic product. Laplace suggested their projection from lunar volcanoes. It has been calculated that a projectile leaving the lunar surface, where there is no atmospheric resistance, with a velocity of 7771 feet in the first second, would be carried beyond the point where the forces of the earth and moon are equal, would be detached, therefore, from the satellite, and come so far within the sphere of the earth's attraction as necessarily to fall to it. But the enormous number of ignited bodies that have been visible, the shooting stars of all ages, and the periodical meteoric showers that have astonished the moderns, render this hypothesis untenable, for the moon, ere this, must have become sensibly impaired, while no trace of an active volcano has yet been discovered on her surface. Olbers was one of the first to prove the possibility of a projectile reaching us from the moon, but at the same time he deemed the event highly improbable, regarding the satellite as a very peaceable neighbour, not capable now of strong explosions from the want of water and an atmosphere. The theory of Chladni will account generally for all the phenomena, be attended with the fewest difficulties, and, Avith some modifications to meet circumstances not known in his day, it is now widely embraced. He conceived the system to include an immense number of small bodies, either the scattered fragments of a larger mass, or original accumulations of matter, which, circulating round the sun, encounter the earth in its orbit, and are drawn towards it by attraction, become ignited upon entering the atmosphere, in consequence of their velocity, and constitute the shooting stars, aerolites, and meteoric appearances that are observed. Sir Humphry Davy, in a paper which contains his researches on flame, strongly expresses an opinion that the meteorites are solid bodies moving in space, and that the heat produced by the compression of the most rarefied air from the velocity of their motion must be sufficient to ignite their mass so that they are fused on entering the atmosphere. It is estimated that a body moving through our atmosphere with the velo city of one mile in a second, would extricate heat equal to 30,000° of Fahrenheit — a heat more intense than that of the fiercest artificial furnace that ever glowed. The chief modification given to the Chladnian theory has arisen from the observed periodical occur rence of meteoric showers — a brilliant and astonishing exhibition — to some notices of which we proceed. The writers of the middle ages report the occurrence of the stars falling from heaven in resplendent showers among the physical appearances of their time. The experience of modern days establishes the substantial truth of such relations, however once rejected as the inventions of men delighting in the marvellous. Conde. in his history of the dominion of the Arabs, states, referring to the month of October in the year 902 of our era, that on the night of the death of King Ibrahim ben Ahmed, an infinite number of falling stars were seen to spread themselves like rain over the heavens from right to left, and this year was afterwards called the year of stars. In some Eastern annals of Cairo, it is related that " In this year (1029 of our era) in the month Redjeb (August) many stars passed, with a great noise, and brilliant light ;" and in another place the same document states : — "In the year 599, on Saturday night, in the last Moharrem (1202 of our era, and on the 19th of October), the stars appeared like waves upon the sky, towards the east and west ; they 138 SCENERY OP THE HEAVENS. flew about like grasshoppers, and were dispersed from left to right ; this lasted till day break ; the people were alarmed." The researches of the Orientalist, M. Von Hammer, have brought these singular accounts to light. Theophanes, one of the Byzantine his torians, records, that in November of the year 472 the sky appeared to be on fire over the city of Constantinople with the coruscations of flying meteors. The chronicles of the West agree with those of the East in reporting such phenomena. A remarkable display was observed on the 4th of April 1095 both in France and England. The stars seemed, says one, " falling like a shower of rain from heaven upon the earth ; " and in another case, a bystander, having noted the spot where an aerolite fell, "cast water upon it, vvhicli was raised in steam, with a great noise of boiling." The chronicle of Rheims describes the appearance, as if all the stars in heaven were driven, like dust, before the wind. "By the reporte of the common people, in this kynge's time (William Rufus)," says Rastel, " divers great wonders were sene — and therefore the kyng was told by divers of his familiars, that God was not content with his lyvyng, but he was so Avilful and proude of minde, that he regarded little their saying." There can be no hesitation now in giving credence to such narrations as these, since similar facts have passed under the notice of the present generation. The first grand phenomenon of a meteoric shower which attracted attention in modern times was witnessed by the Moravian Missionaries at their settlements in Greenland. For several hours the hemisphere presented a magnificent and astonishing spectacle, that of fiery particles, thick as hail, crowding the concave of the sky, as though some magazine of combustion in celestial space was discharging its contents towards the earth. This was observed over a wide extent of territory. Humboldt, then tra velling in South America, accompanied by M. Bonpland, thus speaks of it : — " Towards the morning of the 13th November, 1799, we witnessed a most extraordinary scene of shooting meteors. Thousands of bodies and falling stars succeeded each other during four hours. Their direction was very regular from north to south. From the beginning of the phenomenon there was not a space in the firmament equal in extent to three diameters of the moon which was not filled every instant with bodies or falling stars. All the meteors left luminous traces or phosphorescent bands behind them, which lasted seven or eight seconds." An agent of the United States, Mr. Ellicott, at that time at sea between Cape Florida and the West India Islands, was another spectator, and thus describes the scene : — "I was called up about three o'clock in the morning, to see the shooting stars, as they are called. The phenomenon was grand and awful. The whole heavens appeared as if illuminated with sky-rockets, which disappeared only by the light of the sun after daybreak. The meteors, which at any one instant of time appeared as numerous as the stars, flew in all pos sible directions, exceptfrom theearth, towards which theyall inclined more or less ; and some of them descended perpendicularly over the vessel we were in, so that I was in constant expectation of their falling on us." The same individual states that his thermometer, which had been at 80° Fahr. for four days preceding, fell to 56°, and, at the same time, the wind changed from the south to the north-west, from whence it blew with great vio lence for three days without intermission. The Capuchin missionary at San Fernando, a AEROLITES. 139 village amid tlie savannahs of the province of Varinas ; and the Franciscan monks stationed near the entrance of the Oronoco, also observed this shower of asteroids, which appears to have been visible, more or less, over an area of several thousand miles, from Greenland to the equator, and from the lonely deserts of South America to Weimar in Germany. About thirty years previous, at the city of Quito, a similar event occurred. So great a number of falling stars were seen in a part of the sky above the volcano of Cayambaro, that the mountain itself was thought at first to be on fire. The sight lasted more than an hour. The people assembled in the plain of Exida, where a magnificent view presented itself of the highest summits of the Cordilleras. A procession was already on the point of setting out from the convent of Saint Francis, when it was perceived that the blaze on the horizon was caused by fiery meteors, which ran along the sky in all directions, at the altitude of twelve or thirteen degrees. In Canada, in the years 1814 and 1819, the stellar showers were noticed, and in the autumn of 1818 on the North Sea, when, in the language of one of the observers, the surrounding atmosphere seemed enveloped in one expansive ocean of fire, exhibiting tlie appearance of another Moscow in flames. In the former cases, a residuum of dust was deposited upon the surface of the waters, on the roofs of buildings, and on other objects. The deposition of particles of matter of a ruddy colour has frequently followed the descent of aerolites ; and may explain popular stories of the sky having rained blood. The next exhibition upon a great scale of the falling stars occurred on the 13th of November, 1831, and was seen off the coasts of Spain and in the Ohio country. This was followed by another in the ensuing year at exactly the same time. Captain Hammond, then in the Red Sea, off Mocha, in the ship Restitution, gives the following account of it : — " From one o'clock A.M. till after daylight, there was a very unusual phenomenon in the heavens. It appeared like meteors bursting in every direction. The sky at the time was clear, the stars and moon bright, with streaks of light and thin white clouds interspersed in the sky. On landing in the morning, I inquired of the Arabs if they had noticed the above. They said they had been observing it most of the night. I asked them if ever the like had appeared before ? The oldest of them replied that it had not." The shower was witnessed from the Red Sea westward to the Atlantic, and from Switzer land to the Mauritius. "We now come to by far the most splendid display on record ; which, as it was the third in 140 SCENERY OF THE HEAVENS. successive years, and on the same day of the month as the two preceding, seemed to invest tho meteoric showers with a periodical character; and hence originated the title of the November meteors. The chief scene of the exhibition was included within the limits of the longitude of 61° in the Atlantic Ocean, and that of 100° in Central Mexico, and from the North American lakes to the "West Indies. Over this wide area, an appearance presented itself, far surpassing in grandeur the most imposing artificial fire-works. An incessant play of dazzlingly brilliant luminosities was kept up in the heavens for several hours. Some of these were of considerable magnitude and peculiar form. One of large size remained for some time almost stationary in the zenith, over the Falls of Niagara, emitting streams of light. The wild dash of the waters, as contrasted with the fiery uproar above them, formed a scene of unequalled sublimity. In many districts, the mass of the population were terror-struck, and the more enlightened were awed at contemplating so vivid a picture of the Apocalyptic image — that of the stars of heaven falling to the earth, even as a fig- tree casting her untimely figs, when she is shaken of a mighty wind. A planter of South Carolina thus describes the effect of the scene upon the ignorant blacks : — "I was suddenly awakened by the most distressing cries that ever fell on my ears. Shrieks of horror and cries for mercy I could hear from most of the negroes of three plantations, amounting in all to about six or eight hundred. While earnestly listening for the cause, I heard a faint voice near the door calling my name. I arose, and taking my sword, stood at the door. At this moment, I heard the same voice still beseeching me to rise, and saying ' 0 my God, the world is on fire !' I then opened the door, and it is difficult to say which excited me most — the awfulness of the scene, or the distressed cries of the negroes. Upwards of one hundred lay prostrate on the ground — some speechless, and some with the bitterest cries, but with their hands raised, imploring God to save the world and them. The scene was truly awful ; for never did rain fall much thicker than the meteors fell towards the earth ; east, west, north and south, it was the same." This extraordinary spectacle commenced a little before midnight, and reached its height AEROLITES. 141 between four and six o'clock in the morning. The night was remarkably fine. Not a cloud obscured the firmament. Upon attentive observation, the materials of the shower were found to exhibit three distinct varieties: — 1. Phosphoric lines formed one class apparently described by a point. These were the most abundant. They passed along the sky with immense velocity, as numerous as the flakes of a sharp snow-storm. 2. Large fire-balls formed another constituency of the scene. These darted forth at intervals along the arch of the sky, describing an arc of 30° or 40° in a few seconds. Luminous trains marked their pat4i, which remained in view for a number of minutes, and in some cases for half an hour or more. The trains were commonly white, but the various prismatic colours occasionally appeared, vividly and beautifully displayed. Some of these fire-balls, or shooting stars, were of enormous size. Dr. Smith of North Carolina observed one which appeared larger than the full moon at the horizon. "I was startled," he remarks, "by the splendid light in which the surrounding scene was exhibited, rendering even small objects quite visible." The same, or a similar luminous body, seen at Newhaven, passed off in a north-west direction, and exploded near the star Capella. 3. Another class consisted of luminosities of irregular form, which remained nearly stationary for a considerable time, like the one that gleamed aloft over the Niagara Falls. The remarkable circumstance is testified by every witness, that all the luminous bodies, without a single exception, moved in lines, which converged in one and the same point of the heavens, a little to the south east of the zenith. They none of them started from this point, but their direction, to whatever part of the horizon it might be, when traced backwards, led to a common focus. Conceive the centre of the diagram to be nearly overhead, and a proximate idea may be formed of the character of the scene, and the uniform radiation of the meteors from the same source. The position of this radiant point among the stars was near y Leonis. It remained stationary with respect to the stars during the whole of the exhibition. Instead of accompanying the earth in its diurnal motion eastward, it attended the stars in their apparent movement westward. The source of the meteoric shower was thus independent of the earth's rotation, and this shows its position to have been in the regions of space exterior to our atmosphere. According to the American Professor, Dr. Olmstead, it could not have been less than 2238 miles above the earth's surface. The attention of astronomers in Europe, and all over the world, was, as may be imagined, strongly roused by intelligence of this celestial display on the western continent : and as the occurrence of a meteoric shower had now been observed for three years successively, at a coincident era, it was inferred that a return of this fiery hail-storm might be expected in succeeding Novembers. Arrangements were therefore made to watch the heavens on the nights of the 12th and 13th in the follow ing years at the principal observatories ; and though no such imposing spectacle as that of 1833 has been witnessed, yet extraordinary flights of shooting stars have been observed in various places at the periodic time, tending also from a fixed point in the constellation Leo. They were seen in Europe and America on November 13th, 1834. The following results of simultaneous observation were ob tained by Arago from different parts of France on the nights of November 12th and 13th, 1836 : — 142 SCENERY OF THE HEAVENS. Place. Paris, at the Observatory Dieppe - Arras - Strasburg Meteors. 170 36 27 85 Place. Von Altimarl Angou - Rochcfort Havre Meteors. 75 49 23 300 On November 12th, 1837, at eight o'clock in the evening, the attention of observers in various parts of Great Britain was directed to a bright luminous body, apparently proceeding from the north, which, after making a rapid descent, in the manner of a rocket, suddenly burst, and scattering its particles into various beautiful forms vanished in the atmosphere. This was succeeded by others all similar to the first, both in shape and the manner of its ultimate disappearance. The whole display terminated at ten o'clock, when dark clouds which continued up to a late hour, overspread the earth, preventing any further observation. In the November of 1838, at the same date, the falling stars were abundant at Vienna : and one of remarkable brilliancy and size, as large as the full moon in the zenith, was seen on the 13th by M.Verusmor off Cherburg, passing in the direction of Cape La Hogue, a long luminous train marking its course through the sky. The same year, the non-commissioned officers in the island of Ceylon were instructed to look out for the falling stars. Only a few appeared at the usual time ; but on the 5th of December, from nine o'clock till midnight, the shower was incessant, and the number defied all attempts at counting them. Professor Olmstead, an eminent man of science, himself an eye-witness of the great meteoric shower on the American continent, after carefully collecting and comparing facts, proposed the following theory : — The meteors of November 13th, 1833, emanated from a nebulous body which was then pursuing its way along with the earth around the sun ; that this body continues to revolve around the sun in an elliptical orbit, but little inclined to the plane of the ecliptic, and having its aphelion near the orbit of the earth ; and finally, that the body has a period of nearly six months, and that its perihelion is a little within the orbit of Mercury. The diagram represents the ellipse supposed to be described, E being the orbit of the earth, M that of mercury, and N that of the assumed nebula, its aphelion distance being about 95 millions of miles, and the perihelion 24 millions. Thus, when in aphe lion, the body is close to the orbit of the earth, and this occurring periodically, when the earth is at the same time in that part of its orbit, nebulous particles are attracted towards it by its gravity, and then, entering the atmosphere, are consumed in it by their concurrent velocities, causing the appearance of a meteoric shower. Arago has suggested a similar theory, that of a stream or group of innumerable bodies, comparatively small, but of various dimensions, sweeping round the solar focus in an orbit which More recently, a very complete catalogue of aerolite falls, amounting to 175, has been analysed with a curious result. By far the greater number are registered for the months of June and July, as compared with the opposite months, December and January. The earth is then at the greatest distance from the sun ; and it appears probable, from Leverrier's investigations, that the mean mass or system of the planetoids is at the same time at its perihelion, and therefore nearest the earth. The conjecture is hence indulged, that aerolites are minute outriders of that remarkable family. Though great obscurity rests upon the subject which may never be dissipated, it is agreed on all hands, that shooting stars, meteoric showers, and aerolites, are identical phenomena periodically cuts that of the earth. A GLANCE AT THE STARS. 143 manifested in different ways ; that independently of the great planets and satellites of the system, there are vast numbers of bodies circling round the sun, both singly and in groups, some also moving as minute moons round the earth ; and that in the course of their revolutions these " starlets," or " meteor-planets," as they have been called, come within the sphere of the earth's attraction, and ere precipitated upon its surface, " as weary and forlorn birds of passage, far out at sea, are entangled in the rigging of vessels, and fall helpless on deck." CHAPTER VII. A GLANCE AT THE STARS. E have been chiefly occupied hitherto with those celestial bodies, which from their conspicuous appearance or changes of position, and some of them from their obvious connexion with the con venience and existence of the human race, have in all ages been objects of special attention. Most of these bodies are situated within the limits of the zodiac, an imaginary zone or girdle extending round the heavens, of about sixteen degrees in breadth. It includes the sun and moon, and also all the planets, with the exception of the planetoids. But in the zodiac, and throughout the whole celestial concave, we see scattered every where a number of radiant points of varying brightness/ which appear to have always the same position with regard to each other. This has originated the title of the fixed stars, by which they are po pularly known. The term, in an absolute sense, is inaccurate ; for recent observations have detected changes in the mutual relations of many of these bodies, and it is pro bable that all of them are subject to translation. Owing to their vast distance, their motions appear exceedingly slow to us, requiring the finest instruments to be per ceptible ; and hence they have a character of permanence in contrast with the planets, and the term " fixed" becomes comparatively applicable. The apparent immobility of these objects renders them of immense use in geography, navigation, and planetary astronomy ; and hence the observation of the sidereal host, and the formation of accurate catalogues of its members, are among the most important of the labours of science. Sir J. Herschel, in magnificent language, before the Astronomical Society, thus referred to the catalogue of Piazzi, published in 1805, containing the places of no less than 7646 stars : — " For what has a Piazzi worn out his venerable age in watching ? The answer is, not to settle mere speculative points in the doctrine of the universe ; not to cater for the pride of man, by refined enquiries into the remoter mysteries of nature, — to trace the path of our system through infinite space, or its history through past and future eternities. These, indeed, are noble ends; the mind swells in their contemplation, and attains in their pursuit an expansion and hardihood which fit it for the boldest enterprise. But the direct practical utility of such labours is fully worthy of their speculative grandeur. The stars are the landmarks of the universe ; and, amidst the endless and complicated fluc tuations of our system, seem placed by its Creator as guides and records, not merely to elevate our minds by the contemplation of what is vast, but to teach us to direct our actions by reference to what is immutable, in His works. It is indeed hardly possible to over-appreciate their value in this point of view. Every well-determined star, from the 144 SCENERY OF THE HEAVENS. moment its place is registered, becomes to the astronomer, the geographer, the navigator, the surveyor, a point of departure which can never deceive or fail him, the same for ever and in all places, of a delicacy so extreme as to be a test for every instrument yet invented by man, yet equally adapted for the most ordinary purposes ; as available for regulating a town clock, as for conducting a navy to the Indies ; as effective for mapping down the intricacies of a petty barony, as for adjusting the boundaries of trans- Atlantic empires. When once its place has been thoroughly ascertained and carefully recorded, the brazen circle, with which that useful work was done, may moulder, the marble pillar totter on its base, and the astronomer himself only survive in the gratitude of his posterity ; but the record remains, and tranfuses all its own exactness into every determination which takes it for a groundwork, giving to inferior instruments, nay, even to temporary contri vances, and to the observations of a few weeks or days, all the precision attained origin ally at the cost of so much time, labour, and expense." In the earliest times of which we have any account, mankind appear to have been acquainted with the use of the stars as celestial guideposts in their travels by land and voyages on the deep. We may conclude their observance in the former circumstances to have had the precedence. Without being aware of some safe and sure method of directing their course by night, acquired in journeys on shore, men would hardly venture upon a night voyage at sea. It is likely that in the great Oriental deserts, those immense plains with few natural landmarks, the useful discovery was made how accurately the traveller may direct his footsteps by a cultivated acquaintance with the stars, which stimulated enterprize upon the pathless waters, and laid the foundations of maritime expeditions. Diodorus Siculus expressly states that travellers in the sandy deserts of Arabia were accustomed to direct their course by the Bears, the two constellations of that name, a fact which the Koran recognises in the passage: — " God has given you the stars to be guides in the dark both by land and sea." The honour of inventing nautical astronomy is usually assigned to the Phenicians, but some knowledge of it prevailed among the Greeks as early as the time of the Trojan war. Ulysses is represented sailing on his raft, sitting at the helm, and watching the stars through the night. While, however, the Greek sailors chiefly confined their observations to Ursa Major, the Phenician navigators made a closer approximation to the north. Aratus tells us, referring to Ursa Minor : — " Observing this, Phenicians plough the main." The renowned pilot of the Trojan fleet, Palinurus, through intently watching the face of the nocturnal heavens at the helm, fell overboard, and for a time was lost to his com panions. The Pleiades are supposed to derive their name from TrXtar, to sail, because, during the winter months, they were of high importance to the benighted Greek mariner. It must appear marvellous in the extreme to the uninformed, that now the skilful navi gator, on a before unvisited ocean, can determine positively where he is, to within a few miles, by means of the stars ; and ascertain his distance from, and true course to, any known meridian or harbour of the globe. From the deck of his ship he has merely to measure the moon's apparent distance from certain stars, to compare the result with their true places as given in the Nautical Almanack for every day in the year, and he finds his lon gitude. There are nine conspicuous stars which are chiefly used for this purpose, owing to their position being contiguous to the moon's path in the heavens; — a Arietis, Alde- baran, Pollux, Regulus, Spica Virginis, Antares, Altair, Fomalhaut, and Markab. The late Captain Basil Hall on one occasion was at sea for eighty-nine days, passing in the interval through a distance of eight thousand miles, without once making land or seeing a single sail on the voyage, but with unerring precision he came direct to his destination. His course lay from San Bias on the west coast of Mexico, through the Pacific Ocean, A GLANCE AX THE STAKS. round Cape Horn, and across the South Atlantic to Rio Janeiro. Arrived within a few days' sail of Rio, he took a set of lunar observations, to ascertain his true position, and the bearing of the harbour, and shaped his course accordingly. Afterwards, as he remarks, *: I hove to, at four in the morning, till the day should break, and then bore up ; for, although it was hazy, we could see before us a couple of miles or so. About eight o'clock it became so foggy, that I did not like to stand in farther, and was just bringing the ship to the wind again, before sending the people to breakfast, when it suddenly cleared off, and I had the satisfaction of seeing the great Sugar-loaf rock, which stands on one side of the harbour's mouth, so nearly right ahead that we had not to alter our course above a point in order to hit the entrance of Rio. This was the first land we had seen for three months, after crossing so many seas, and being set backwards and forwards by innumerable currents and foul winds." The crew might well cheer their skilful commander upon en tering the port. On a clear night in winter, when the moon is absent, the heavens exhibit an aspect of great brilliancy, attractive to the eye of childhood and maturity. But to see the stars to advantage, in the utmost of that glory which they reveal to the gaze of man, we must cruise in tropical seas, or wander with the Bedouins in their deserts. There, through a more transparent medium, the lesser lights of heaven shine with a lustre and vivacity of which we have no conception, who are only familiar with a denser atmosphere. Known to be at a distance from us, in comparison with which the interval between us and the farthest planet is but a hand- breadth, the stars far surpass that planet in their light, and hence it follows that they are not like him dependent upon the central luminary of our system, but self-luminous bodies, independent suns. This is rendered unquestionable by the fact, that while every reflected light is susceptible of polarisation, the light of the stars, like that of the sun, is incapable of it. The tremulous emission of the stellar light, the scintillation or twinkling of the stars, is a remarkable feature, and was long a puzzle to philosophers. It is now generally supposed to arise from the molecules of the atmo sphere constantly undergoing sudden compressions and dilatations, which produce changes in its refractive power, and consequent changes in the direction of the rays of light, 146 SCENERY OF THE HEAVENS. apparently every moment displacing the stars. The effect is not so sensible in the case of the planets because of their disks. These, though small, are of sufficient magnitude to bear without so much disturbance the minute agitations of the atmosphere, whereas the stars, being only brilliant points, without any perceptible diameter, are completely displaced. It has been observed, that in serene climates, and on the tops of high mountains, the twinkling of the stars is much less powerful than when viewed from other situations, which tends to confirm the preceding explanation as the true one. On directing the eye to the celestial vault, the impression made upon the mind is that of an incalculable number of stars being visible — that of the army of heaven consisting of a host which our arithmetic will not suffice to reckon. It is well known that this is an optical illusion. Their twinkling and disorderly position in the sky confuse and deceive the sight. They are so scattered as not to be included at once in the field of vision. Hence arises the idea, that the visible number, which is really very limited, is, on the contrary, immense. This is the popular notion, and it is borne out by our first optical impressions. But an ordinary eye will not be able to discern much above a thousand in our firmament under the most favourable circumstances ; and including both hemispheres, three thousand will be the outside number which a keen and experienced gaze will reach. The Greek and Arabian astronomers distinguished some of the brightest stars by particular names, which are recognised in our nomenclature of the heavens, as Sirius, Aldebaran, Rigel, Arcturus, Capella, Canopus, and Fomalhaut, though a different mode of proceeding is now adopted, having become necessary by the large additions made to the ancient catalogues. To distinguish the stars in a constellation, the letters of the Greek alphabet are now employed ; when these are exhausted, those of the Roman are used ; and when these fail, numerals are resorted to. Thus a designates the most bril liant star of a group, ft the next most conspicuous, y the third, and 2 the fourth. In this way, the relative brightness of the members of particular constellations is indicated, not that of the stars in general, for y Virginis is equal in brightness to a Aquarii. This method was first introduced by John Bayer of Augsburg, in his " Uranometria, " in 1603; who thus ranged the stars in the order of brilliancy, as they then appeared to the naked eye, and it has been adopted by most succeeding astronomers. Referring to the whole host of heaven, the stars are divided into classes, according to their apparent magnitudes, which range from those of the first magnitude, or the brightest, down to the sixteenth ; but all after the sixth are invisible to the naked eye, and are hence called telescopic objects. Of the stars in both hemispheres, within reach of a practised gazer, which in round numbers may be stated to be three thousand, the following are about the proportions belonging to the different classes : — First magnitude - - -20 Second - - 70 Third - - - -220 Fourth magnitude 500 Fifth - 690 Sixth - - - 1500 From direct experiments with the photometer, an instrument for measuring the intensity of light, Sir "W. Herschel inferred as follows : — Light of a star of the average first magnitude = 10O second = 25 third = 12 fourth = 6 fifth = 2 sixth = 1 The intensity of the light, therefore, of a first class star, according to this estimate, is a hundred times greater than that of one belonging to the sixth. Sir John Herschel has arrived at a different conclusion, having found the light of Sirius, the brightest star in the heavens, about 324 times that of an average star of the sixth magnitude. A GLANCE AT THE STARS. 147 The stars are further distinguished by being formed into artificial groups or con stellations. This is a convenient arrangement in itself, analogous to the civil divisions of the globe, its empires, states and cities. But, unfortunately, celestial objects have not been grouped with judgment and care, having been the work, for the most part, of unknown authors in an age remote and rude. Hence we have constellations running into each other, men, animals, birds, and dragons, jumbled together in the most disorderly manner. Eu- doxus of Cnidus, a contemporary of Plato, about 370 years before Christ, sent forth a description of the face of the heavens, containing the names and characters of all the constellations recognised in his time. Though this production has perished, yet a poetical paraphrase of it, written about a century later, is still extant, the work of Aratus, a Cilician, and probably a native of Tarsus. This astronomical poem opens with a statement of the dependence of all things upon Jupiter, whose children all men are, and who has given the stars as the guides of agriculture. " With Jove we must begin ; not from Him rove ; Him always praise, for all is full of Jove ! He fills all places where mankind resort, The wide-spread sea, with ev'ry shelt'ring port Jove's presence fills all space, upholds this ball ; All need his aid, his power sustains us all. For we his offspring are ; and He in love Points out to man his labour from above ; Where signs unerring show when best the soil By well-tim'd culture shall repay our toil." This passage has acquired great interest from the circumstance of the part in italics having been quoted by Paul in his address to the Athenians, himself a man of Tarsus. The poem of Aratus describes the configurations of all the constellations then in use, with their respective times of rising and setting, amounting to forty-five, all of which are represented on our present celestial globes. They are the twelve zodiacal, with twenty in the northern hemisphere, and thirteen in the southern. The next enumeration occurs in the " Alma gest" of Ptolemy, which includes the preceding, with three additional, one northern and two southern constellations, making in all forty-eight. These are the ancient stellar groups. Large accessions have been made to the nomenclature in modern times, in consequence of maritime discovery having made us acquainted with regions of the heavens upon which the ancient eye never gazed. "When the Europeans began to navigate the southern hemisphere and effected a passage round the Cape of Good Hope, many stars of course appeared which are never seen by the inhabitants of the north ; and from these numerous additions have been made to the old constellations. Some stars also of the northern heavens not included in the ancient groups have been formed into new ones. In 1751 Lacaille went to the Cape for the purpose of making a catalogue of the southern stars, and forming them into constellations, an undertaking which he prosecuted with great ardour for nearly four years at the expense of the French government. Flattery has also contributed its mite towards the stellar nomenclature. Upon the restora tion of Charles H., the evening before his return to London, Sir Charles Scarborough, the court physician, was gazing upon a star in the northern heavens, which shone with greater luminosity than usual, as might be expected from a loyal star on such an occasion. This, in connection with a few others, was formed into Cor Caroli, the heart of Charles H., by Halley, at the doctor's recommendation. In the following list the constellations of both hemispheres at present recognised are given, with the number of stars in each, and the names of the constructors ; but those of Aratus and Ptolemy merely denote the constellations that are found in their lists, and all that the former enumerates must be added to those recorded by the latter. }48 SCENERY OF THE HEAVENS. ZODIACAL CONSTELLATIONS. N«m« of Constellation. Author. No. of Stan. Principal Stars. MM* am Aratus 6G a Arietis, 2 Courtis, the Bull, Gemini, the Twins, " 141 85 Aldebarau, Castor, Pollux, 1 1-2 dancer, the Crab, " 83 95 Acubcns, Regulus, Denebola, 3 1-2 ^('o, the Ajion, Argo, the Virgin, Libra, the Balance, M no 51 Spica Virginis, Zubenich Meli, I Scorpio, the Scorpion, » 44 Antares, Sagittarius, the Archer, >• 69 51 3apricornus, the Goat, Aquarius, the Water-bearer, " 108 Scheat, 3 •isces, the Fishes, ** 113 NORTHERN CONSTELLATIONS. Ursa Minor, the Lesser Bear, Jrsa Major, the Great Bear, ?erseus, and Head of Medusa, Auriga, the Waggoner, Bootes, the Herdsman, • 24 87 59 66 54 80 Pole-star, Dubhe, Alioth, Algenib, Algol, Capella, Arc'turus, Rastaben, 3 1-2 2-2 1 1 3 Draco, the Dragon, " 35 Alderamin, 3 Canes Venatici, the Greyhounds Astoria and Chara, Cor Carol!, Heart of Charles II. Hevelius Halley 25 3 Triangulum, the Triangle, Triangulum minus, Musca, the Fly, Aratus Hevelius Bode Hevelius 16 10 6 44 Leo Minor, the Lesser Lion, Coma Berenices, Berenice's Hair, Cameleopardalis, the Giraffe, Mons Menelaus, Mount Menelaus, Corona Borealis, the Northern Crown, TychoBrahe Herelius Aratus 53 43 58 11 21 Serpens, the Serpent, Scutum Sobieski, Sobieski's Shield, Hercules with Cerberus, Serpentarius, or Ophiuchus. the Serpent-bearer, Taurus Poniatowski, the bull of Poniatowski, Lyra, the Harp, Vulpeculus et Anser, the Fox and Goose, Sagitta, the Arrow, Aquila, the Eagle, with Antmous, Pelphinus, the Dolphin, Hevelius Aratus Poczobat Aratus Hevelius Aratus 8 113 74 7 22 37 18 71 18 81 Ras Algratha, Ras Aliagus Vega, Altair, Dencb, .1 1 1 1 Cygnus, the Swan, Cassiopeia, the Lady in her Chair, Equulus, the Horse's Head, Lacerta, the Lizard, Pegasus, the Flying Horse, Ptolemy Hevelius Aratus H 10 16 89 66 Markab, Almaac, 3 2 Andromeda, Tarandus, the Reindeer, Lemounier 12 SOUTHERN CONSTELLATIONS. Tlie * indicates those constellations which never rise in North latitude 52°. Apparatus Sculptoris », the Sculptor's Apparatus, Eridanus Fluvius, the River Po, Bayer Lacaille Aratus 13 12 84 Acherncr, 1 Hydrus *, the Water Snake, Cetus, the Whale, Fornax Chemica, the Chemical Furnace, Bayer Aratus Lacaille 97 14 12 Menkar, 2 Horologium* the Clock, Rheticulus Rhomboidialus,* the Rhomboidal Net, „ 10 Xiphias Dorado*, the Sword Fish, Celapraxitellis, the Engraver's Tools,* Bayer Lacaille 16 19 Lepus, the Hare, Arama 1 A Columba Noachi, Noah's Dove, Halley Aratus IU 78 Betelgeuse, Iligel, 1 Orion, Argo Navis, the Ship Argo, Canis Major, the Great Dog, Equuleus Pictoris, the Painter's Easel, Monoceros, the Unicorn, Canis Miuor, the little Dog, Lacailie Heveliu* Ptolemy 64 31 8 31 14 In Canopus, Sirius, Procyon, 1 I 1 Chameleon », Pyxis Nautica, the Mariner's Compuss, Piscis Volan»«, the Flying Fish, Hvdra, the Serpent, Sextans, the Sextant, Robur Carolinum*, the Oak of Charles II., Bayer Lacaille Bayer Aratu"i Hevelius Halley IV 4 8 60 41 12 Cor Hydrx, 1 Antlia Pneumatica, the Air Pump, Crater, the Cup, Lacaille Aratus 3 31 9 Alker, Algorab, 3 3 Corvus, the Crow, ,, Crux *, the Cross. Royer Apis Musca, the Bee, or Fly, Bayer 4 A GLANCE AT THE STARS. Name of Constellation. Author. No. of Star*. Principal Star,. Magnitude. Avis Indica*, the Bird of Paradise, 11 Circinus *, the Compass, Lacaille 4 Centaurus, the Centaur, Aratus 35 Lupus, the Wolf, „ 24 Norma, or Euclid's Square, Lacaille 12 Triangulum Australis*, South Triangle, Bayer 5 Ara», the Altar, Aratus 9 Telescopium *, the Telescope, Corona Australis, the Southern Crown, Lacaille Ptolemy 9 12 Pavo*, the Peacock, Bayer 14 Indus*, the Indian, M 12 Microscopium, the Microscope, Lacaille 10 Octans Hadliensis*, Hadley's Octant, ,, 43 Grus,* the Crane, Bayer 14 Toucan, the American Goose, 9 Piscis Australis, the Southern Fish, Aratns 24 Fomalhaut, 1 Mons Mensa*, the Table Mountain, Lacaille 30 Constellations. Stan. Zodiacal ... North .... South - - - - 12 35 , - 46 1016 1456 995 93 3467 The stars included in this list are not all visible to the naked eye. They are those whose declination and right ascension have been accurately ascertained, and inserted chiefly in Flamstead's catalogue. Declination is the distance of any heavenly body either north or south of the equinoctial, measured on a meridian. Right ascension is its distance east from the first point of Aries, measured on the equinoctial. The former corresponds to terrestrial latitude, and the latter to terrestrial longitude ; but while declination, like latitude, may extend to 90°, and no more, right ascension is reckoned only in one direc tion, and may therefore extend round the sphere, or to 360°, whereas terrestrial longitude, being reckoned east and west, can only extend to 180°. Owing to the precession of the equinoxes, a change has occurred in the relation be tween the signs of the zodiac and their respective asterisms, which is somewhat puzzling to the general reader, who is apt to confound the sign with the constellation called after it. Two thousand years ago, in the days of Hipparchus, the zodiacal signs and asterisms corresponded, so that when the sun entered the first point of the sign Aries, he entered also the constellation of that name. Then the equinoctial colure, — an imaginary great circle passing through the poles of the heavens and the sun's place at the vernal equinox, intersected the stellar ram, as some ancient representations testify. But as the equinoctial points retrograde about 50" annually, they have receded nearly 31° since the time of Hipparchus, or more than a whole sign. The effect has been to separate the asterisms from their denominational signs, so that the constellation Pisces is now in the sign Aries, the constellation Aries in the sign Taurus, and the tropics of Cancer and Capricorn, according to the sun's place among the stars, have become the tropics of Gemini and Sagittarius. Four thousand years back, anterior to the time of the Hebrew patriarchs, the sun was in the asterism Taurus at the vernal equinox, and the Bull opened the astronomical year ; and two thousand years hence, the asterisrn Aquarius will occupy the present position of Pisces, and lead on the celestial 150 SCENERY OF THE HEAVENS. host for a similar period. All confusion will be avoided, by discriminating between the constellations and the signs of the zodiac, though bearing the same name, understanding by the former the asterisms, and by the latter certain sections of the ecliptic. In about twenty- three thousand years, the zodiacal constellations and signs will again nominally agree. The constellation ARIES is situated in the heavens next east of Pisces, and midway between Triangulum and Musca on the north, and the head of Cetus on the south. It is readily distinguished by means of two bright stars in the head of the Ram, about 4° apart, the brightest being the most north-easterly of the two. This is the nautical star a Arietis, called Hamal by the Arabs, of the second magnitude ; the other, She- ratan, is of the third. Here is one instance out of many, where stars of more than ordinary brightness are seen together in pairs, the brightest being gene rally on the east. TAURUS, one of the finest of the zodiacal asterisms, has Perseus and Auriga on the north, Gemini on the east, Orion and Eridanus on the south, and Aries on the west. It includes the two remarkable clusters, the Pleiades and Hyades, the former on the shoulder, and the latter in the face of the Bull, about 11° apart. The Hyades consist of five stars, so placed as to form the letter V, the brilliant star, Aldebaran, of the first magnitude, being on the top of the letter to the left. This group is just rising in the east when Aries is about 27° high. The Pleiads have gone through some evil and good report Figuring conspicuously in our winter sky, Statius calls them a snowy constellation ; Valerius Flaccus speaks of their danger to ships ; while Horace pictures the south-wind lashing the deep into storm in the presence of the stellar sisterhood. But as the Pleiades were more in juxtaposition with the sun at the vernal equinox in by-gone days than at present, the Romans sometimes called them Vergilias, or the " Virgins of the Spring." GEMINI is situated with the Lynx on the north, Taurus on the west, Cancer on the east, Monoceros and Canis Minor on the south. It is easily known by the two principal stars, Castor and Pollux, the former of the first, and the latter of the second mag nitude, about 4^° apart. The constellation was anci ently represented by two kids, which the Greeks changed into the twin-brothers after whom the two stars are named, and which the Arabians altered into peacocks. A small star of the fifth magnitude, Propus, is memorable on account of Herschel finding Uranus in its neighbour hood, and as having served for many years to guide astronomers to that planet. CANCER is inferior to most of the other constel lations along the solar highway, having no conspicuous stars. Two of the fourth magnitude the Romans called Aselli ; and a nebulous cluster of very minute stars, sufficiently luminous however to be seen by the naked eye, exists at the distance of about 2° from the Asses. This cluster goes by the name of Praesepe, or the Manger, out of accommodation to them. A GLANCE AT THE STARS. 151 LEO, situated next east of Cancer, and directly south of Leo Minor and Ursa Major, makes a fine brilliant appearance in the sky, boasting " Two splendid stars of highest dignity ;" with several that are conspicuous objects. Eegulus, a star of the first magnitude, and Denebola, one of the second, are about 25° apart, the former in the breast of the Lion, hence often called Cor Leonis, the other is situated in the tail. VIRGO, represented as a woman holding an ear of corn, a mythological personage, has Leo on the east, Coma Berenices on the north, and Corvus on the south. The asterism is rich in stars, the chief of which is Spica Virginis, a first-class star in the wheat-ear, known by its solitary splendour, there being no visible star near it but one of the fourth magnitude. For this reason, it was called by the Arabs As-Simak'al-a'zal^the unarmed or defenceless Simak. The place of this star, as determined by Hipparchus, compared with a similar determination a century and a half before, led to the discovery of the precession of the equinoxes. LIBRA, the balance, the em blem of the office of Virgo as the goddess of justice, has four subordinate but still conspicuous stars. They form a quadrila teral figure, two on the north east, about 7° apart, and two on the south-west, about 6° apart; distinguishing the Scales. SCORPIO exhibits a beautiful collection of stars. One of the first magnitude, the fiery An- tares, is a paramount object in this region of the heavens. Four smaller stars form an arc over him not unlike a boy's kite, and ten more conspicuous extend from him in a crooked line, answering to a kite's tail. SAGITTARIUS has none but subordinate stars, but many of these are very distinct, and may be ranged into a variety of geometrical figures. Eight of the principal form two quadrangles, nearly alike, four in and four out of the Milky Way, by which the con stellation is readily distinguished. CAPRICORNUS, with Cancer, is one of the least striking of the zodiacal asterisms, but one of the celebrated among the ancients, as the sign under which Augustus and Vespasian born, hence accounted the harbinger of good fortune, and as marking the southern 152 SCENERY OF THE HEAVENS. tropic, or winter solstice, and therefore called the " Southern Gate of the Sun." Now, in consequence of the precession of the equinoctial and solsticial points, the sun is in the sign Capricorn at midwinter, but does not reach the constellation until the middle of January. AQUARIUS is more easily recognisable by the eye, having four stars distinctly forming the letter Y about the urn which the water-bearer is pictured emptying of its contents. The Arabs, not being allowed by their prophet to depict the human figure, represented this asterism by a mule carrying water- barrels, and for the same reason they changed the twins Gemini into peacocks. PISCES is a loose assemblage of small stars, diffi cult to be traced, occupying a large triangular space in the heavens. This is now the first constellation in order in the zodiac, that which presides over the vernal equinox, a position to be occupied for cen turies to come, but ultimately resigned to Aquarius, after a tenure of office extending to somewhat more than two thousand years. It will be seen, that the most imposing of the zodiacal asterisms are those which the sun now traverses in our summer months. They are then lost to us by reason of his effulgence, but are splendid objects during the long 'nights of winter. The time, however, will arrive, when the sun's high road will lie through these asterisms in winter, and Taurus, Gemini, and Leo, will be lack ing in our heavens during the winter nights, appear ing in the nights of summer, but with less splendour, owing to the strength and duration of the twilight. Directing attention to the constellated groups of the northern hemisphere, the most conspicuous and splendid is Ursa Major, supposed to have derived its name from its situation near the north pole, and from its constant visibility in our unclouded night sky, because the polar regions are the haunts of the bear, an animal which neither makes extensive journeys nor rapid marches. It is singular that the Iroquois, a savage tribe in the back settlements of America, should have designated this region of the heavens by the name which the earliest Arabs of Asia applied to it, the Great Bear — two nations, lar remote from each other, employing a title which is purely arbitrary, as the group of stars exhibits no resemblance to the animal. The asterism, however, figured as well to the ancient eye under the form of a waggon drawn by a team of horses, and the name of Charles's Wain is still its popular denomination in some of our rural districts, from the Karl-Wagen, or peasant's cart of our Gothic ancestors. Before the invention of time pieces, when the peasantry practised star-gazing to ascertain the time of the night, the position of this constellation was their common guide : hence the carrier's remark in Shakspeare, " An't be not four by the day, I'll be hanged, Charles's Wain is over the new chimney, and yet our horse not packed!" This is also the Helice of classical literature introduced in the celebrated description of the night in the "Argonautics:" - A GLANCE AT THE STARS. Io3 " Night on the earth pour'd darkness ; on the sea The wakesome sailor to Orion's star And Helice turn'd heedful. Sunk to rest, The traveller forgot his toil ; liis charge The sentinel ; her death-devoted babe The mother's painless breast. The village dog Had ceas'd his troublous bay. Each busy tumult Was hush'd at that dead hour ; and darkness slept, Lock'd in the arms of silence. She alone, Medea, slept not." As Ursa Major is always above the horizon of Europe, it has been an object of universal observation to its inhabitants in all ages of the world, and is familiarly known to those who take no interest in astronomy by three stars which form a triangle in the tail, and four a quadrangle in the body of the Bear. Commencing with the former, the first star at the tip of the tail is Benetnasch of the second magnitude ; the second Mizar, and the third Alioth ; and passing to the latter the first star at the root of the tail is Megrez ; the second below it, Phad ; the third in a horizontal direction, Merak ; and the fourth above the latter, Dubhe, of the first magnitude. By common consent, the two latter stars, Merak and Dubhe, are called the Pointers, because an imaginary line drawn from the lower to the upper, and carried on in the same direction, passes almost over Polaris in Ursa Minor, a star close to the north polar point of the heavens, from which its name is derived. It may be useful here to state, for the purpose of measuring angular distances in the heavens with the eye, that the space between the Pointers may be approximately considered 5°, and between the Pointers and the pole-star, 29°. The direction merely of the polar star is exhibited in the diagram, and not the distance. Ursa Minor has no conspicuous stars, nor any thing remarkable in its appearance ; but from the important service rendered by its position to naviga tion and surveying, it has engrossed more of the serious attention of mankind than any other constellation in the skies. Polaris is a star between the second and third magnitude. It appears stationary during the apparent daily revolu tion of the sphere, the rest of the stars in the asterism making a complete swing round it every twenty-four hours, as in the diagram. The pole-star is not, however, the true polar point, but at present about 1° 32' from it, a distance which will be lessened down to 26' 30" about the year 2100. At the time when the Chaldean shepherds watched the heavens, a star in Draco, now 24° 52' from the polar point, was within 10' of it, and was consequently the pole-star of that era. The proximity of Polaris to that point in the heavens which is directly opposite the north pole of the earth, enables the mariners and travellers in the northern hemisphere with facility to find their latitude, for the distance of a place from the equator is always equal to the altitude of the pole. The navigator therefore applies his quadrant to the polar star, ascertains its elevation, and after making allowance for its polar aberration, he arrives at his latitude. The same advantage is not enjoyed on the other side of the equator, for the southern heavens have no guide so convenient to the south polar point. In close attendance upon the Bears, the ancients arranged the asterism Arctophylax, the Bear-keeper, other wise called Bootes, the Herdsman, now represented holding in his left hand the leash of the two grey- 154 SCENERY OF THE HEAVENS. hounds of Hevelius, apparently pursuing Ursa Major round the pole of the heavens. The fine star Arcturus, of the first magnitude, is in this constellation, once supposed to be the nearest to the earth of the stellar. host, but without authority. Of the stars of the southern hemisphere, only a portion of course are visible to us, but these are by far the most important, and constitute the finest stellar objects upon which we gaze. There is the beautifully splendid Orion, visible to all the habitable world, be cause the equinoctial passes through the middle of the constellation, and when on the meridian with us, we have at the same time the most remarkable asterisms in the firmament above the horizon. The outline of Orion is very distinctly marked by four brilliant stars which form a long square or parallelogram. The most northerly is Betelguese of the first magnitude ; 7-J-0 westward is Bellatrix of the second; 15° to the south is Rigel, a splendid star of the first magnitude; and 82° to the east is Saiph of the third. The two former form the upper ends of the parallelogram, and the two latter the lower. In the centre are three stars of the second magnitude, in a straight line of about 3° in length, running from north-west to south-east. These form the well-known belt of Orion. The uppermost of the triad being less than ^° south of the equinoctial, is almost exactly verti cal to the equator. South of the Belt, a row of smaller stars running down obliquely towards Saiph forms the Sword. This fine asterism, in connection with the groups in its neighbourhood, constitutes the richest part of the visible heavens. But the ancients regarded Orion with fear and trembling, referring to him without ceremony those squalls upon the deep which were observed to be periodical at his rising at certain seasons of the year. Hesiod and Homer, therefore, call him fierce; Virgil connects him with storms and tempests ; Horace points to his severity and turbulence ; and Polybius divides the blame of losing the Roman fleet in the first Punic war between the malignity of the constellation and the fool-hardiness of the consuls. .^Eneas accounts in this way for the storm which cast him on the coast of Africa when proceeding to Italy : — " To that blest shore we steer'd our destin'd way, When sudden, dire Orion rous'd the sea : All charg'd with tempests rose the baleful star, And on our navy pour'd his wat'ry war." Orion has the bright clusters of Taurus giving splendour to his vicinity on the north west ; Canis Minor with Procyon, a star of the first magnitude, on the east ; and Canis Major, a little on the south-east, universally known by the brilliancy of Sirius, the most refulgent and perhaps the nearest object to us in the sidereal heavens. The old Egyptians observed the heliacal rise of Sirius, or the appearance of the star in the morning above the horizon just before the sun, to occur at a period which immediately anteceded the annual overflow of the Nile, and supposing the two coincident events to be physically con nected, the dog-star was adored as the author of the fertility of their country. To the Greeks, his heliacal rising taking place at the most sultry time of the year, when disease was rife, seemed to authorise a reference of all the plagues of the season to his in fluence. Hence the description of " the star Autumnal — of all stars, in dead of night Conspicuous most, and warn'd Orion's dog — A. GLANCE AT THE STARS. 155 Brightest it shines, but ominous and dire Disease portends to miserable man." South-east of Cards Major is the asterism of the ship Argo, in which Canopus shines, the second of the stars in point of lustre, but invisible to all parts of the earth of higher latitude than the southern coast of the Mediterranean. An observer in the northern hemisphere can only see the stars as many degrees south of the equinoctial in the southern hemisphere as his own latitude lacks of 90°. All whose southern declination is greater never reach his horizon. Among the stars of the south with which the stay-at-home Europeans are only acquainted by report, the constellation of the Cross is described as pre-eminent — the most interesting object in the sky of that hemisphere on account of the associations connected with it by a Christianised imagination. It consists of four bright stars, to which the fancy readily gives a cruciform shape, the upper and lower being the pointers to the south pole. Von Spix and Martins, in their travels in Brazil, remark :— " On the 15th of June, in lat. 14° 6' 45", we beheld for the first time that glorious constellation of the southern heavens, the Cross, which is to navigators a token of peace, and, according to its position, indicates the hours of the night. "We had long wished for this con stellation, as a guide to the other hemisphere ; we therefore felt inexpressible pleasure when we perceived it in the resplendent firmament. We all contemplated it with feelings of profound devotion as a type of salvation ; but the mind was especially elevated at the sight of it by the reflection, that even into the region which this beautiful constellation illumines, under the significant name of the Cross, the European has carried the noblest attributes of Christianity, and, impelled by the most exalted feelings, endeavours to spread them more and more extensively in the remotest regions." Humboldt also refers to his first view of this constellation with peculiar feeling : " We saw distinctly, for the first time," he observes, " the Cross of the South, on the night of the fourth and fifth of July, in the sixteenth degree of latitude ; it was strongly inclined, and appeared from time to time between the clouds, the centre of which, furrowed by uncondensed lightnings, reflected a silver light. The pleasure felt on discovering the Southern Cross was warmly shared by such of the crew as had lived in the colonies. In the solitude of the seas we hail a star as a friend, from whom we have been long separated. Among the Portuguese and the Spaniards peculiar motives seem to increase this feeling ; a religious sentiment attaches them to a constellation, the form of which recals the sign of the faith planted by their ancestors in the deserts of the New World. The two great stars which mark the summit and the foot of the Cross have nearly the same right ascension ; it follows that the constellation is almost perpendicular at the moment when it passes the meridian. This circumstance is known to every nation that lives beyond the tropics or in the southern hemisphere. It is known at what hour of the night, in different seasons, the Southern Cross is erect, or inclined. It is a timepiece, that advances very regularly nearly four minutes a day ; and no other group of stars exhibits to the naked eye an observation of time so easily made. How often have we heard our guides exclaim in the savannas of Venezuela, or in the deserts extending from Lima to Truxillo, ' Midnight is past, the Cross begins to bend ! ' How often these words reminded us of that affecting scene, where Paul and Virginia, seated near the source of the river of Lotaniers, conversed together for the last time ; and when the old 156 SCENERY OF THE HEAVENS. man, at the sight of the Southern Cross, warns them that it is time to separate ! " Mrs. Hemans has entered into the feeling here described, and sung of the Southern Cross in the spirit of a settler in the New World from old Spain : — " But to thee, as thy lode-stars resplendently burn In their clear depths of blue, with devotion I turn, Bright Cross of the South ! and beholding thee shine, Scarce regret the loved land of the olive and vine. Thou recallest the age when first o'er the main My fathers unfolded the ensign of Spain, And planted their faith in the regions that see Its unperishing symbol emblazon'd in thee. Shine on — my own land in a far distant spot, And the stars of thy sphere can enlighten it not, And the eyes that I love, tho' e'en now they may be O'er the firmament wandering, can gaze not on thee 1 But thou to my thoughts art a pure blazing shrine, A fount of bright hopes and of visions divine ; And my soul, like an eagle exulting and free, Soars high o'er the Andes to mingle with thee ! " A powerful impression is made upon the mind by the changed aspect of the celestial vault upon a first voyage to the southern hemisphere. The thought of being far from home occurs with a power never known before. By degrees, many of the old stars, those which have been watched in the northern sky, in the days of childhood and youth, with such interest and delight, decline towards the horizon, sink below it, and are looked for in vain. Others customarily seen in the south approach the zenith, and pass to the north, while strangers rise above the southern horizon, ascending higher and higher, till a new heaven appears aloft, without any intimation that the old earth has passed away. Generally speaking, the southern celestial hemisphere is extremely dissimilar to the northern, not only in the grouping of the stars, but in its whole character. There are many large tracts or spaces of deep and solemn blackness— starless voids to the naked eye— which do not occur, or but rarely, in our own firmament. But these unlighted spaces give great effect by their darkness to the constellations; and render them in a high degree rich and magnificent. Yet notwithstanding these voids, as they appear to the naked eye, the southern firmament, when telescopically examined, is thought to be rather richer in stars than the northern. To examine those regions of the heavens which are hid by southern declination from the view of the stay-at-home Europeans, astronomers have frequently visited localities beyond the equator. They were first systematically and scientifically surveyed by Halley, who, though only in his nineteenth year, was expressly selected by the Koyal Society for this mission. He sailed to St Helena, and spent two years, 1676-8, upon the island, its climate was found unfavourable for observation, he executed his work in a manner which procured him the name of the southern Tycho, in allusion to that astronomer's labours on an island of the Baltic. Lacaille next proceeded to the Cape of Good Hope, in 1751, under the auspices of the French government, and resided there four years, during which he observed ten thousand stars, measured an arc of the meridian, and the length o: the second's pendulum. In 1820 the British government established an observatory at the Cape, and appointed the Rev. F. Fallows its director, a post now honourably held by Mr A GLANCE AT THE STARS. 157 Maclear. An observatory was also erected in 1821 at Paramatta, in New South Wales, by Sir T. Brisbane, the governor of the colony, who procured the Messrs Rumker and Dunlop to superintend it. Another was established by the government at St Helena in 1830, and placed under the care of a scientific officer who happened to be on duty in the island, Lieutenant Johnson, now director of the Radcliffe Observatory, Oxford. There is also one at Madras sustained by the East India Company. In 1835 Sir John Herschel repaired to the Cape, and executed an elaborate series of observations on the distribution of the stars of the southern firmament. Addressing an assembly held to commemorate his return from the successful enterprise in 1838, he stated: — "I believe there is scarcely a corner in that part of the southern sky which I have not twice searched over, with almost the power of a microscope ; and it may easily be supposed, in the course of a rummage of that kind, what an extraordinary turn-out there must have been, and what numerous objects worthy of attention must have shewn themselves ; and often have I longed for some of those keen star-gazing eyes which I see now directed upon me. I need hardly say anything on the subject of the southern constellations. They are extremely superb things." To know the heavens at night so as to recognise the principal constellations and stars visible in our hemisphere — the first step of the tyro — seems at first a difficult undertaking. But a little practice, with the aid of good celestial charts, will soon make him feel at home in a cruise along the firmament. After becoming acquainted with the more remarkable groups, and their chief constituents, these will serve as an index to those that are less conspicuous. The maps accompanying this work, with the directions connected with them, will supply every requisite help for the purpose. The best time for a survey of the heavens is during the long nights of winter in the absence of the moon ; but in seeking to find his way among the stars by the aid of a celestial chart or globe, the student must bear in mind, that while their relative positions and distances are given, the constellations are continually varying their direction by reason of the apparent revolution of the sphere, after the manner of Ursa Minor swinging round Polaris, as represented in a previous diagram. By alignment, or drawing imaginary lines from star to star, forming a variety of geometrical figures, a general knowledge of them may be speedily acquired. Having become acquainted with the seven stars which compose the triangle and square of Ursa Major, his circumpolar neighbours are readily found by this method. Thus, while a straight line through the side of the square formed by the Pointers leads to Polaris, another through the top of the square inverse to the triangle leads to Capella, and from the first star of the triangle nearest the square a line carried through Polaris conducts to the bright cluster of Cassiopeia. From Capella a direct line through Polaris passes to the two stars Alwaid and Etaniin in the head of Draco. Through the side of the square opposite the Pointers a line continued southward conducts to Regulus, east of which is Denebola, the two principal stars in Leo. Denebola forms an extensive square, with Cor Caroli occupying the northern point, Arcturus the eastern, and Spica Virginis the southern, in the interior of which is a cluster of small stars, the Coma Berenices of Tycho Brahe. The line joining Arcturus and Spica Virginis is also the base of a conspicuous triangle, of which Antares in Scorpio is the vertex to the east; and a large right-angled triangle is very nearly formed by Arcturus, Polaris, and Vega. Another remarkable figure, called the great square of Pegasus, is composed by the four leading stars in that constellation. Every one is familiar with the belt of Orion. A straight line drawn through it northerly leads to Aldebaran, and southerly to Sirius. The star north-east of the belt, Betelguese, forms a triangle, with Pollux at the northern, and Procyon at the eastern point. By the practice of align ment, guided by a good map, the leading objects of the firmament will soon be recognised, 158 SCENERY OF THE HEAVENS. nor is any costly observatory necessary in order to cultivate a more intimate acquaint ance. Ferguson sought fellowship with the stars lying on his back in the fields when a shepherd boy, and measured their relative distances by means of beads upon a thread. Harding discovered one of the planetoids from the house-top. Upon the bridge of Prague, which now spans the Moldau with its sixteen arches, Keppler was accustomed to watch the stars ; and Lalande, in his old age, often took his station upon the Pont Neuf, for the same purpose, ready to accommodate a passing Parisian with a peep at Algol. CHAPTER VHI. NUMBER, DISTANCE, AND MAGNITUDE OF STARS. HE prevailing ideas of men concerning the multitude of the stars, though founded upon wrong premises, are yet in harmony with the literal fact, for the conclusion drawn from the hasty obser vation of the eye, which a persevering survey would at once disprove, is itself established by telescopic examination. So enormous is the number of the stars, yet so completely incalcu lable are they, as to admit of their being joined with the sand upon the sea-shore, as a figure of speech denoting a numeration which we cannot define. The common phrase of the Sacred Volume, the hosts of heaven, alludes to their multitude ; and the fact is advanced as an illustration of the infinite grasp of the Creator's mind, that he is acquainted minutely with these multitudinous worlds, which immeasurably exceed our utmost estimates. " He calleth them all by names by the greatness of his might, for that he is strong in power; not one faileth." The earliest catalogue of the stars, that of Ptolemy, enumerates only 1022 : that of Ulugh Beigh, the grandson of Tamerlane, made at Samarcand, contains 1017 : but a comparison of the ancient with modern catalogues exhibits a striking difference in the assigned richness of the asterisms, of which a few samples may be advanced. Aries - Ursa Major Bootes Leo - Virgo Taurus Orion Ptolemy. - 18 stars. - 35 - 23 - 35 - 32 - 44 . 38 Tycho Brahe. 21 stars. 56 28 40 39 43 62 Hevelius. 27 stars. 73 52 50 50 51 62 Flamstead. 66 stars. 87 54 95 110 141 78 Bode. 148 stars. 338 319 337 411 394 304 Upwards of two thousand stars have however been counted within the trapezium or un equal square of Orion, and the telescope multiplies them in the heavens without end, revealing points of light profusely distributed throughout all space, every point a sun attended probably by a train of planets, a reasonable inference from the constitution of the solar universe. Lalande in the last century registered the positions of fifty thousand, the various astronomers of Europe upwards of a hundred thousand, and Struve alone has since observed no less than a hundred and twenty thousand stars. But this is only a feeble approximation to the whole amount within telescopic range, which a moderate com- NUMBER, DISTANCE, AND MAGNITUDE OP STARS. 159 putation gives at 100,000,000, a number from which, if our globe and system were stricken they would no more be missed than a unit taken from " the autumnal leaves that strew the brooks In Vallambrosa. " There are several parts of the firmament in which stars appear to the naked eye closely packed together, and others which present a general indivisible luminosity to the unas sisted vision. The chief of these are the Pleiades, Hyades, the Milky Way, and Presepe. The latter is a region faintly gleaming in the sombre districts of Cancer, which may be easily found by running a line through Castor and Pollux and continuing it to the south east about three times the distance between those stars. The ancients were acquainted with Presepe, a speck of light which they supposed to be the general effect of three stars, as it is not resolvable into component parts by the unaided gaze ; but Galileo with his imperfect means discovered it to be a congress of thirty-six. The Hyades appear to consist of five stars, but between thirty and forty are readily discernible under a moderate instrumental power. The Pleiades also yield a similar result, their optical number, six or seven, being largely multiplied by the application of a telescope. The constituents of the group are thus stated in modern catalogues : — Keppler - - 32 stars. Hook - - 78 De la Hire - 64 Rheita - - 118 But the cluster easily resolves into about forty constituents. Of the Milky Way the Roman poet wrote, as the path leading to great Jupiter's abode, whose "groundwork is of stars." Milton, likewise, speaks of that " broad and ample road, whose dust is gold, and pavement stars." These poetical conceptions become verities when an instrument suf ficiently powerful is directed to the zone in question. It is found to be composed of stars which assume the appearance of a tortuous consecutive girdle of light, owing to their grouping and distance. Some idea may be formed of their profuseness from the fact that Herschel was led to the conclusion, when examining this wonderful region, that in some parts of it no less than fifty thousand were included within a zone two degrees in breadth, which passed under his review in a single hour's observation. Yet this is but a specimen of countless combinations which are discoverable in the concavity of the heavens, so remote from us as to escape the observation of the eye, yet recognised by its aided vision, forming clusters of various shapes, as rich in stars as the zone which we can analyse proves to be. That luminous celestial highway which the Greeks called the Galaxy, and the Romans the Via Lactea, from its whiteness, is more or less visible at all seasons of the year ; but in northern latitudes it is seen to the best advantage in the interval between the cl'ose of July and the beginning of November. It varies in breadth from four to eighteen degrees, and also in brightness, being most resplendent in the southern hemisphere, about the constellations Argo Navis, Robur Carolinum, and the Cross. " The general aspect," says Sir John Herschel, " of the southern circumpolar region, including in that expres sion 60° or 70°, is in a high degree rich and magnificent, owing to the superior brilliancy and larger development of the Milky Way ; which from the constellation of Orion to that of Antinous, is in a blaze of light, strangely interrupted, however, with vacant and almost starless patches, especially in Scorpio near a Centauri and the Cross ; while to the north it fades away pale and dim, and is in comparison hardly traceable." This vast zone is a sensible annulus in the heavens, though this may be an optical illusion. It passes from the head of Cepheus about 30° from the North Pole, through Cassiopeia, nearly coverino- Perseus, over part of Auriga, and crossing the ecliptic between the feet of Gemini and the horns of Taurus, proceeds over the equinoctial into the southern hemisphere to within 20° 160 SCENERY OF THE HEAVENS. of the South Pole. It then takes a northerly direction, and divides into two branches before again passing the ecliptic into the northern hemisphere. The eastern branch streams over the bow of Sagittarius, through Aquila and part of Cygnus. The western branch passes over the tail of Scorpio, the right side of Ophiucus to Cygnus. The two branches unite in that constellation, and pass to Cepheus, the point from whence we started, where the stream has its greatest breadth for a considerable space. By some of the pagan philosophers the Via Lactea was regarded as an old disused path of the sun, of which he had got tired, or from which he had been driven, and had left some faint impression of his glorious presence upon it. Its stellar composition was, however, suspected long before it was proved, but its multitudinous host of stars remained a secret till Herschel turned his mighty instrument at Slough upon the silvery belt. In a single spot he counted between five and six hundred without moving his telescope ; and in a space of the zone not more extensive than 10° long by 2^° wide, he computed that there were no fewer than 258,000. "What Omnipotence !" was the involuntary exclamation of Schroeter of Lilienthal, upon examining a part of the same magnificent girdle. Though the whole number of stars which the naked eye discerns on an ordinary night is small, yet, leaving the common haunts of men, and gazing upon the celestial vault at a high elevation in the atmosphere, largely improves the appearance of old fami liar stellar faces, and many are caught sight of which were before wholly invisible. Visiting the peaks of lofty mountains, the unaided eye of the adventurer who is there at night forms fresh acquaintances among the stars, and its friends of long standing glitter with a brilliance which the denser regions of the atmosphere render obscure to the dwellers below. The son of Marshal Ney remarks, in a personal narrative of the ascent of one of the Pyrenean summits : — " How glorious were the heavens on that night ! Ye who have never bivouacked on the Cardal know not what a fine night is." Brydone observes of the top of Mount Etna : — " We had now time to pay our adorations in a silent contemplation of the sublime objects of nature. The sky was clear, and the immense vault of the heavens appeared in awful majesty and splendour. We found ourselves more struck with veneration than below, and at first we were at a loss to know the cause, till we observed, with astonishment, that the number of stars seemed to be infinitely increased, and the light of each of them appeared brighter than usual The whiteness of the Milky Way was like a pure flame that shot across the heavens, and with the naked eye we could observe clusters of stars that were invisible in the regions below. We did not at first attend to the cause, nor recollect that we had now passed through ten or twelve thousand feet of gross vapour, that blunts and confuses every ray before it reaches the surface of the earth. We were amazed at the distinctness of vision, and exclaimed together, ' What a glorious situation for an observatory ! Had Empedocles possessed the eyes of Galileo, what discoveries must he not have made !' We regretted that Jupiter was not visible, as I am persuaded we might have discovered some of his satellites with the naked eye, or at NUMBER, DISTANCE, AND MAGNITUDE OF STARS. 161 least with a small glass which I had in my pocket." "Surely," he adds in another passage, " the situation alone is enough to inspire philosophy." To measure the distance of the stars, is a task which has baffled the ablest men, armed with the best instruments for the purpose, and using them with the utmost nicety and perseverance. Until our own day, the conclusion arrived at had only been negative. It could merely be demonstrated, that the nearest of these bodies must at the least be removed from us a certain space, the extent of which requires the billions of our arithmetic to express. It is clearly ascertainable, that the enormous interval intervening between us and that remote wanderer in our system, Neptune, is but a narrow chasm compared with the interval between him and the most contiguous of the stellar orbs. On observing the same star, lying in the plane of the earth's orbit, from the two extremities of the orbit, at the end of six months, no perceptible alteration in the apparent size of the star can be discerned, notwithstanding this vast change of situation. The inference therefore is, that the diameter of the earth's orbit, the immense line of 190 millions of miles, bears no sensible proportion to the real distance of the stars. But another method adopted to measure the great gulf, and most laboriously pursued for more than two centuries, has been the detection, if possible, of an annual parallax of the stars, or apparent change of place caused by being viewed from opposite extremities of the earth's orbit. All the planets, even the remotest, appear in veiy different places when viewed at the vernal and autumnal equinoxes, or at any two extreme points of our globe's path; and if the angle subtended be given, the distance may be calculated. But no parallax of a star amounting even to a single second has been detected, and Bradley makes the observation, which Sir John Herschel confirms, that if such an amount of parallax existed, it could not possibly have escaped notice. Supposing, however, a parallax of one second perceptible, that, by the rules of trigonometry, would give a distance from us of more than 19 billions of miles; but as there is no such quantity detectable, there is no star lying within that range — they all lie beyond it ! Parallax is the apparent change of place which an object undergoes through an observer shifting his own position. The traveller in journeying marks a great change in the same scenery, in the disposition of its various features, by the alteration of his own point of view. He observes the trees, fields, and hedgerows, which appeared in a direct line between him and some distant hill, at one station, making an angle with the eminence as seen from another station. Suppose we stand at a, and have two trees before us in the direct line a b c, both will be projected to the same point d, but if we shift our position to e, then the nearest tree will be seen in the direction /, and the farthest in the direction g. By measuring the base line a e, and the angles a b e, and a c e, or the parallax, the niathema- * tician readily arrives at the distance of the trees from the points of observation. Now, with reference to estimating the distances of the stars, we have the diameter of the earth's orbit as a capital base line to work upon, a real change of place occurring annually on our part in relation to them amounting to 190 millions of miles. Yet, notwithstanding this vast alteration of position, no angle of the value of a second has been found with certainty in the case of any star. The diagram now subjoined, exhibits the earth at two extreme points of its orbit. Let the reader keep in mind the 190 millions of miles between those points, and SCENERY OP THE HEAVENS. then he may form some idea of the awful gulf between us and the stars, from the fact that the triangle formed by lines drawn from the extremes of the orbit to a star at the vertex, has defied the most perfect instruments of human invention to measure, so inappre ciable is it. Supposing the whole of that orbit filled with a globe resplendent as the sun, it would have a circumference of 600 millions of miles, and yet have only the appearance of a twinkling atom as seen from the nearest of the stars. Previous to the determinations of Newton, the discovery of an annual parallax of the stars was a point of great interest in order to confirm the Copemican doctrine of the earth's motion in space. It was remarked by opponents, that if we are really sweeping at a prodigious rate in an enormous ellipse around the sun, then ought the stars to appear continually displaced, just as do the trees of the forest to the traveller flying swiftly past them, instead of which, seen from any point, and at any time, their position is ever the same— fixed, immutable, eternal. Hence the stars were confidently appealed to as bright and unimpeachable witnesses of the falsity and extravagance of the Copernican system. This reasoning was well founded. Only one reply could be made to it, that such was the enormous distance of the sphere of the fixed stars, that no perceptible change was occa sioned by the revolution of the earth in its orbit. More than three centuries have rolled away since the controversy commenced. Though long since terminated by the truth of the grand theory of Copernicus being triumphantly established, yet astronomers have prosecuted with zeal the search after an annual parallax of the stars, in order to illustrate the scale upon which the universe is built ; but no success attended the effort until our time. Bradley failed to detect the slightest indication of it in the instance of y Draconis, elaborately watched; but was unexpectedly led by the attempt to his great discovery of the aberration of light. Herschel, too, was equally unsuccessful in the pursuit of the same object, yet similarly fortunate, as his labours on the occasion were rewarded with the disclosure, that the double stars are not examples of accidental optical proximity, as before supposed, but bodies physically connected, magnificent systems of revolving suns. The problem of stellar remoteness has been solved in the present age, in the first instance by the late Professor Bessel, of Konigsberg, and has been justly styled a magni ficent conquest. The world is indebted for it to one of the refracting telescopes of the celebrated Frauenhofer, of Munich, an instrument of extraordinary power, specially adapted to the research for the parallax of the fixed stars. To give some idea of the delicacy of the contrivances with which these great telescopes are provided, Mr Mitchel, of the Cincinnati Observatory, states, that the micrometer of his refractor is capable of dividing an inch into 80,000 equal parts ! When mechanical ingenuity failed to construct lines of mathematical minuteness, the spider lent his aid, and it is with his^ delicate web that these measures are accomplished. Two parallel spiders' webs are adjusted in the focus of the eye-piece of the micrometer, and when the light of a small lamp is thrown upon them, the eye, on looking through the telescope, sees two minute golden wires, straight and beautiful, drawn across the centre of the field of view, and pictured on^ the heavens. The observer has them completely under his control, and can so revolve them as to bring them into any position, increasing or decreasing their distance at pleasure. With machinery even more delicate than this, better adapted to the purpose, and of a somewhat different kind, Bessel renewed the search after the unattained parallax of tL stars. His instrument, called the Jieliometer, was mounted in the year 1829, but various causes delayed his principal operations up to the month of October 1837. NUMEEE, DISTANCE, AND MAGNITUDE OF STAES. 163 The astronomer selected the star 61 Cygni as the one on which to perform his opera tions. Several reasons influenced Bessel in the selection of this object. First, it is so near the pole, that, with the exception of a small part of the year, it can always be observed at night at a sufficient distance from the horizon. Second, it is a conspicuous binary star, specially adapted by its double character to the instrument employed. Both the constituents are yellow, but one smaller than the other has the deepest tint. Third, the region occupied by 61 Cygni contains a number of minute stellar points close to it, presenting admirable fixed points for measurement. Fourth, the star has long been known to be distinguished by the great rapidity of its proper motion. In watching this star, Bessel commonly took observations sixteen times every night whenever opportunity offered. Without detailing the course he pursued, which would be uninterest ing and unintelligible to most readers, it will be sufficient to state, that after a most careful investigation, a variation in the apparent place of the star began to show itself, increasing precisely as parallactic variation ought to increase, and diminishing as it ought to diminish. The period of these changes was precisely a year ; and in all particulars they corresponded exactly to the changes which ought to be produced by parallax. Still, on account of their minute character, the observer hesitated to place dependence upon them. But during another year of observation, the same results came out, and the previous values were confirmed. This was the case also during a third year ; and all doubt being now removed, Bessel announced to the world that he had compassed the hitherto impassable gulf of space, and measured the distance to one of the fixed stars. The final conclusion deduced, confirmed by the subsequent researches of M. Peters at the Observatory of Pulkowa, assigns to 61 Cygni an annual parallax of 0"'349, rather more than one-third of a second of space. This corresponds to the enormous distance of nearly 600,000 radii of the earth's orbit, or as many times 95,000,000 miles. The distance of the star may therefore be set down in round numbers at sixty billions of miles. The mighty gulf which separates us from the stars having been once passed, the route has been followed ; and succeeding observers have determined the parallax of a sufficient number of stars to show that their results are entirely trustworthy. That of a Centauri, a double star of the first magnitude, and one of the brightest sidereal objects in the southern hemisphere, was next ascertained. This was effected by Professor Henderson, during his residence as astronomer at the Observatory of the Cape of Good Hope. This star exhibits the greatest amount of parallax hitherto observed ; and is consequently the nearest of any yet examined. General dependence may be placed on the results given in the table : Stars. Parallax. 1. a Centauri, . . 0"-913 2. 61 Cygni, . . 0 -348 3. a Lyrse, . . 0 -261 4. Sirius, . . 0 -230 5. 1830. Groombridge, 0 -226 6. i Ursae, . .0-133 7. Arcturus, . . 0 127 Distance in Radii of the Earth's Orbit. 225,920 592,715 790,287 896,804 912,677 1,550,864 1,624,134 Distance in Billions of Miles. 21 56 75 84 86 147 154 Observers. Henderson. Bessel. Struve. Henderson. Peters. Peters. Peters. To aid the imagination in forming some idea of these distances, it may be stated, that the conflagration of these stars would not be announced to us under periods varying from upwards of three years to more than a quarter of a century, for a ray of light, which darts to us from the sun in eight minutes, would require that time to travel through the space between us and them. One delicate thread of a spider's web, placed before the 164 SCENERY OF THE HEAVENS. eye of a spectator at 61 Cygni, would hide from his view the whole orbit of the earth ; and a single hair would conceal the entire solar universe ! The remark of Huygens is a sober speculation, that there may be worlds in the immensity of space, which have been long created, whose light, owing to their distance, has not yet reached our globe, though still destined to come within range of the eye. " How distant some of the nocturnal suns ! So distant, says the sage, 'twere not absurd To doubt, if beams, set out at Nature's birth, Are yet arriv'd at this so foreign world ; Though nothing half so rapid as their flight." However marvellous the statement, it is strictly true, that when we gaze upon the heavens, observe the stars, and note down their positions, we are witnessing and chro nicling their appearances in by-gone time, and not the present aspect of the phenomena. The ray that meets the eye from the nearest sidereal object brings intelligence of its past estate ; and that Past includes years in relation to the front ranks of the stellar army, and ages with respect to the general body. When we reflect upon these facts, and remember that the faint nebulous clusters are far more remote from the distinct stars than they from us — that the light which manifests their presence now may have left its source when the Tudor, Norman, or Saxon race occupied the throne — we catch a glimpse of the immensity of space, and of the infinity of that Being who originated the great government of which it is the scene, and conducts it with such nicety that a sparrow falleth not to the ground without Him. We have nothing to guide us respecting the magnitude of the stars beyond their visibility, when so vastly remote. The planet Saturn is magnified by the telescope larger than the moon to the naked eye, though 900 millions of miles distant ; but instrumental power fails in giving any appreciable magnitude to the stars. It brings countless multitudes into view hid from the unassisted sight ; it makes us sensible of their presence ; it increases their brilliancy : but beyond this, it supplies us with no informa tion respecting their volume and mass. Halley remarked, that " the diameters of Spica Virginis and Aldebaran are so small, that when they happen to immerge behind the dark edge of the moon, they are so far from losing their light gradually, as they must do if they were of any sensible magnitude, that they vanish at once with all their lustre, and emerge likewise in a moment, not small at first, but at once appear with their full light, even although the emersion happen when very near the cusp, where, if they were four seconds in diameter, they would be many seconds of time in getting entirely separated from the limb. But the contrary appears to all those who have observed the occultations of those bright stars." The largest and most brilliant of the stars, if occulted at the dark limb of the moon, Sir John Herschel observes, " is, as it were, extinguished in mid-air, without notice or visible cause for its disappearance, which, as it happens instantaneously, and without the slightest previous diminution of its light, is always surprising ; and if the star be a large and bright one, even startling from its suddenness." The simple fact of the visibility of the stars across the mighty expanse which we know to exist between them and ourselves, necessarily gives us high ideas of their dimensions. Calculations have been made, from a comparison of the light of the stars with that of the sun, but the result can only be regarded as a rude approximation. Let us consider the case of Sirius, the brightest in the heavens. The light of Sirius, as determined by Sir John Herschel, is 324 times that of an average star of the sixth magnitude. The ratio of his light to that of the sun has been calculated to be, using round numbers, as 1 to 5,000,000,000, that is, the illumination supplied by the star is that number of times less than the illumination afforded by the sun. But we have seen, that while the sun is ninety-five millions of miles from us, NUMBER, DISTANCE, AND MAGNITUDE OF STARS. 165 the star is 896,804 times the same distance ; and it is a well-known law, that the light which the eye receives from a luminous object will diminish in the same proportion as the square of the distance increases. Now supposing the sun and the star to have equally brilliant surfaces, and the former to be removed to the same distance as the latter, it is computed that the stellar lustre would exceed that of the solar in the proportion of 146 to 1. The conclusion is thus arrived at, that the surface of Sirius is 146 times greater than the surface of the sun. Now we cannot suppose the magnificent orb of Sirius to dwell alone. As our smaller sun has planets with their satellites circulating round him, rejoicing in his light, it is rea sonable to infer that a much larger globe serves a similar purpose, and is the common centre of a more numerous family, refreshed and beautified by the glorious beams that emanate from it. The inference holds good with reference to every star, for that all the stars are suns admits not of a moment's doubt, and we are justified in attributing to each its dependent Jupiters and Saturns. Thus we gain some insight into the economy of the universe, and gather rational ideas of its immeasurable amplitude — its multitude of worlds — its countless myriads of sentient beings. Sir John Herschel soberly answers the enquiry : " For what purpose are we to suppose such magnificent bodies scattered through, the abyss of space ? Surely not to illuminate our nights, which an additional moon of the thousandth part of the size of our own would do much better — not to sparkle as a pageant void of meaning and reality, and bewilder us among vain conjectures. Useful, it is true they are to man, as points of exact and permanent reference ; but he must have studied astronomy to little purpose, who can suppose man to be the only object of his Creator's care, or who does not see, in the vast and wonderful apparatus around us, provision for other races of animated beings. The planets derive their light from the sun ; but that cannot be the case with the stars. These doubtless, then, are themselves suns, and may perhaps, each in its sphere, be the presiding centre round which other planets, or bodies of which we can form no conception from any analogy offered by our own system, may be circulating." These views are reasonable, elevating, and useful. It is well to become familiar with them. Though of the extent and arrangements of that wondrous fabric of which our system forms one of the minuter parts, it may be said, that such knowledge is too wonderful for us, yet some measure of intelligence is placed within our reach, and we may grasp it with high advantage. He who has read but a few pages of the magnificent book of the universe, and has enstamped upon his mind a lively impression of the greatness of that scheme of exist ence with which he is connected, is in circumstances to steer clear of the two extremes into which unreflecting humanity is often betrayed, those of arrogant self-importance and puling imbecility. Man — the lord of a few acres — while absorbed with his terrestrial patrimony, is prone to forget the higher duties of life, and to rest content with taking part in the pageant of an hour, stepping across his fields in the pride of a self-satisfaction at being the proprietor of the scene. Or in other situations — in contact with the grander class of terrestrial phenomena — the thunder reverberating among the mountains, the lightning playing around their peaks, and the tempest-clouds discharging their torrents — he is apt to feel and to display an abject spirit appropriate to the grovelling worm. But he who possesses a cultivated acquaintance with his true position in the scheme of the creation — that glorious whole of which the world is but an infinitesimal part, yet man a member of the intellectual part — will have views, which, legitimately used, will be a safeguard against self-idolatry and abasement. 166 SCENERY OF TUE HEAVENS. CHAPTER IX. NEW, VARIABLE, AND COMPOUND STARS. i HEN we compare the present appearance of the sidereal heavens with the records of former catalogues, some stars are not to be found now whose places have been registered. There are four in Hercules, four in Cancer, one in Perseus, one in Pisces, one in Hydra, one in Orion, and two in Berenice's Hair, which have apparently disappeared from the sky. Of the eight stars formerly mentioned which were marked in the catalogue of Ptolemy, but had been lost in the time of Ulugh Beigh, there were six near the Southern Fish, which have not been observed since ; and, as four of these were of the third magnitude, Bailly concludes that they were really visible in the heavens in the age of Ptolemy, and disappeared in the interval between him and the Tartar prince. It is no doubt probable that apparent losses have often arisen from mistaken entries ; yet, in many instances it is certain that there is no mistake in the observation or entry, and that stars have really been observed, and as really have disappeared. A star of the fifth magnitude, 55 Herculis, in the catalogue of Flamstead, was particularly observed by Herschel in 1781 and 1782 ; but nine years afterwards it was gone, nor has it since been seen. Sir John Herschel, in May 1828, missed a star in Virgo, inserted in Baron Zach's catalogue, and has never been able to perceive it. " There are now wanting in the heavens," Montanari observed in 1670, " two stars of the second magnitude, in the stern and yard of the ship Argo. I and others observed them in the year 1664, upon occasion of the comet that appeared that year. When they first disappeared I know not ; only I am sure that on the 10th of April, 1668, there was not the least glimpse of them to be seen." On the other hand, there are some stars now in the heavens which are supposed to have only recently become visible. No entry of them occurs in the catalogues of former observers, who have registered objects of inferior magnitude in their neighbourhood, and would not therefore have omitted these had they been present. Thus, a star in the head of Cepheus, one in Gemini, another in Equuleus, a fourth in Sextantis, a remarkable one between ft and 3 Hydrse, a sixth in Hercules, and several others, are not given in Flamstead's catalogue. These are probably new, as that most accurate observer of the heavens could scarcely have omitted them. Since the year 1826 a star in the nebula of Orion has appeared ; and attention has been specially called to it, owing to its having started as it were into existence in a situation which apparently strengthened the now exploded nebular hypothesis. In addition to these changes, the occurrence of stars starting into temporary visibility, shining with great lustre, and then entirely vanishing, however unaccountable, is so well authenticated as to obtain a place in the class of unquestionable phenomena. An instance of this kind occurred in the year 389 of our era. In the neighbourhood of Altair, in the constellation Aquila, a star suddenly appeared, continuing as brilliant as Venus for three weeks. Other stellar apparitions are recorded in the years 945 and 1264 ; but the most memorable case occurred in 1572, which we had occasion to notice in tracing the career NEW, VARIABLE, AND COMPOUND STABS. 167 of Tycho Brahe. The new star, which glowed with great splendour, and continued visible for eighteen months, appeared in Cassiopeia immediately under the scabellum or chair of the Lady. It was first caught sight of at Wittemburg on August 6th, seen at Augsburg on the 7th, observed by Corne lius Gemma on November 9th, and by Tycho on the llth. It formed an irregular square with three of the principal stars of the constellation, maintained the same position invariably with respect to them during the whole time of its apparition, ex hibited no sensible parallax, which plainly declared its place to be in the region of the fixed stars. In the diagram, the largest star represents the stranger, with Caph above it on the left hand, Schedir a little higher to the right, and y below. To account for the appearance of this novel object, some philosophers of the time referred it to the Epicurean doctrine of a fortuitous concourse of atoms, whose combination in this stellar form was merely one of the endless varieties of ways in which they have been arranged. Keppler, too enlightened to be attracted by such a worn-out hypothesis when advanced upon a subsequent occasion, thus alludes to it with his characteristic oddity: — "When I was a youth, with plenty of idle time on my hands, I was much taken with the vanity, of which some grown men are not ashamed, of making anagrams, by transposing the letters of my name written in Greek so as to make another sentence : out of IwawrjQ KeTrXr/poc, I made Ztiprjvwv caTTi/Ao? (the tapster of the Sirens) ; in Latin, out of lohannes Keplerus came Serpens in akuleo (a serpent in his sting). But not being satisfied with the meaning of these words, and being unable to make another, I trusted the thing to chance, and taking out of a pack of playing cards as many as there were letters in the name, wrote one upon each, and then began to shuffle them, and then at each shuffle to read them in the order they came, to see if any meaning came of it. Now may all the Epicurean gods and goddesses confound this same chance ! which, although I spent a good deal of time over it, never showed me anything like sense, even at a distance. So I gave up my cards to the Epicurean Eternity, to be carried away into Infinity, and, it is said, they are still flying above there in the utmost confusion among the atoms, and have never yet come to any meaning. I will tell these disputants my opponents, not my own opinion, but my wife's. Yesterday, when weary with writing, and my mind quite dusty with considering these atoms, I was called to supper, and a salad I had asked for was set before me. — " It seems then," said I aloud, " that if pewter dishes, leaves of lettuce, grains of salt, drops of water, vinegar and oil, and slices of egg, had been flying about in the air from all eternity, it might at last happen by chance that there would come a salad." " Yes," says my wife, " but not one so nice or well dressed as this of mine is." The above amusing extract is taken from one of the treatises of this remarkable man, entitled De Stella Nova, a presentation copy of which to our James I. is in the library of the British Museum. It was written upon a new star which blazed forth in the year 1604 under somewhat remarkable circumstances. In that year the planets Saturn, Jupiter, and Mars were in conjunction in the three fiery signs Aries, Leo, and Sagittarius, to use the language of astrology, composing the fiery trigon, a phenomenon which occurs about once in every eight hundred years. The scene drew Keppler many a night to the bridge of Prague, his usual place of observation. Towards the close of September he observed the three planets, and on the 29th Mars and Jupiter were in conjunction, and that part of the heavens was attentively watched, but nothing peculiar otherwise was observable. On the 30th a strange object was seen by his scholars at no great distance from Jupiter, 168 SCENERY OF THE HEAVENS. far surpassing that planet in magnitude and equal to Venus in brilliancy. Owing to unfavourable weather at Prague, it was not until the 8th of October that Keppler obtained a view of it. It appeared near the right foot of Serpentarius, exhibited no parallax, displayed a variety of colours, and after an apparition of twelve months it vanished from the heavens, and has not again been visible. Comparing this new star with its pre decessor, Keppler remarks: — "Yonder one," referring to that in Cassiopeia, "chose for its appearance a time no way remarkable, and came into the world quite unexpectedly, like an enemy storming a town, and breaking into the market-place before the citizens are aware of his approach ; but ours " (the new star in Serpentarius) " has come exactly in the year of which astrologers have written so much about the fiery trigon that happens in it, just in the month in which (according to Cyprian) Mars comes up to a very perfect conjunction with the other two superior planets ; just in the day when Mars has joined Jupiter, and just in the place where this conjunction has taken place. Therefore the apparition of this star is not like a secret hostile irruption, as was that of 1572, but the spectacle of a public triumph, or the entry of a mighty potentate ; when the couriers ride in some time before, to prepare his lodgings, and the crowd of young urchins begin to think the time over long to wait ; then roll in, one after another, the ammunition, and money, and baggage waggons, and presently the trampling of horse, and the rush of people from every side to the streets and windows ; and when the crowd have gazed with their jaws all agape at the troop of knights, then at last the trumpeters, and archers, and lackeys, so distinguish the person of the monarch, that there is no occasion to point him out, but every one cries out of his own accord, ' Here we have him !' What it may portend is hard to determine, and thus much only is certain, that it comes to tell mankind either nothing at all, or high and weighty news, quite beyond human sense and understanding. It will have an important influence on political and social relations, not indeed by its own nature, but as it were accidentally, through the disposition of mankind. First, it portends to the booksellers great disturbances and tolerable gains, for almost every Theologicus, Philosophicus, Medicus, and Mathematicus, or whoever else, having no laborious occupation intrusted to him, seeks his pleasure in studiis, will make particular remarks upon it, and will wish to bring these remarks to the light. Just so will others, learned and unlearned, wish to know its meaning, and they will buy the authors who profess to tell them. I mention these things merely by way of example, because, although thus much can be easily predicted without great skill, yet may it happen just as easily, and in the same manner, that the vulgar, or whoever else is of easy faith, or, it may be, crazy, may wish to exalt himself into a great prophet ; or it may even happen that some powerful lord, who has good foundation and beginning of great dignities, will be cheered on by this phenomenon to venture on some new scheme ; just as if God had set up this star in the darkness merely to enlighten them." Another example of a temporary star appeared in the year 1670. It was observed by Hevelius, and by Don Anthelme, on the 20th June, in the head of Cygnus. The last instance occurred on the night of April 28, 1848, when Mr. Hind noticed a new star in a part of Ophiuchus. It exhibited no change of place, but diminished in brightness, and became extinct. There are now about twenty well-attested cases of fixed stars suddenly glowing from out the sombre bosom of infinity, shining with great vivacity for an interval, so as to be visible even in the day time through the intensity of their light, then gradually fading away, and becoming entirely extinct. We are completely foiled by these apparent tem porary stellar creations. Are they worlds which, having accomplished one cycle of their existence, have had their physical structure dissolved by fire, to be remodelled ? Arc they thus bodies which have lain hid from terrestrial gaze by their remoteness, until NEW, VARIABLE, AND COMPOUND STARS. 169 some vast combustion has given them a transient visibility? "Worlds and systems of worlds," says Mason Good, "are not only perpetually creating, but also perpetually disappearing. It is an extraordinary fact, that within the period of the last century, not less than thirteen stars, in different constellations, seem to have totally perished, and ten new ones to have been created. In many instances it is unquestionable, that the stars themselves, the supposed habitation of other kinds or orders of intelligent beings, together with the different planets by which it is probable they were surrounded, have utterly vanished, and the spots which they occupied in the heavens have become blanks ! What has befallen other systems, will assuredly befall our own. Of the time and the manner we know nothing, but the fact is incontrovertible ; it is foretold by revelation ; it is inscribed in the heavens ; it is felt through the earth. Such, then, is the awful and daily text; what then ought to be the comment?" The current of thought upon this subject, with reference to several eminent men, has run in the same channel. Vince remarks: — " The disappearance of some stars may be the destruction of that system at the time appointed by the Deity for the probation of its inhabitants ; and the appearance of new stars may be the formation of new systems for new races of beings then called into existence to adore the works of their Creator." Laplace likewise observes: — "As to those stars which suddenly shine forth with a very vivid light, and then immediately disappear, it is extremely probable that great conflagrations, produced by extraordinary causes, take place on their surface. This conjecture is confirmed by their change of colour, which is analogous to that presented to us on the earth by those bodies which, are set on fire and then gradually extinguished." It has been said, that the existence and death of Alexander the Great — the rise and fall of the Roman empire — the destruction, by earthquake or volcano, of cities which were once the seats of commerce and the arts — have been handed down to us upon evidence in no respect whatever better entitled to our belief, than that of the astronomical facts to which we have been adverting. This is perfectly true ; yet the facts themselves may be widely apart from any analogy with such terrestrial occurrences. We have choice of another theory, on many accounts preferable, though not free from great difficulties. It has been con jectured, that the temporary appearance of stars may be resolvable into a periodical translation from the depths of infinite space, to a station which brings them within the bounds of our vision. Their sudden and brilliant burst from the dark and distant void, upon this supposition, arises from a tremendous velocity ; and their evanescent stay within our view, may be caused by one of the narrow extremities of an orbit immensely elliptical lying in the direction of our system. The diagram represents part of this supposed orbit, that which approaches our position in the universe. It is further conceived, that the temporary stars of 945. 1264, and 1572 were not different individuals, but in reality the same star. This is grounded upon the close accordance of the intervals separating the periods. From 945 to 12G4, 319 years. From 1264 to 1572, 308 years. It has been supposed, therefore, that the star has an orbit which it accomplishes in about three hundred years. With reference to this hypothesis, it will be for the present century to utter a verdict. If it be true, those who survive but a few years longer will see the star, upon which Tycho gazed in his manhood, and Keppler when a boy, return to its station in Cassiopeia, again to glitter, to wane, and vanish ! In corroboration of this theory, it should be mentioned, that the stars of 945. 1264, and 1572 appeared in the 170 SCENERY OF THE HEAVENS. same part of the heavens. The chief difficulty which lies in the way of the supposition, . that the temporary stars are objects moving in orbits, which display them periodically to us, is, that no change of place has been observed during the whole time of apparition. Besides cases of apparent stellar creation and complete extinguishment, there are a number of stars whose light undergoes a periodical increase and diminution, forming the class called variable. Some retire for a time into absolute invisibility, while others merely suffer changes in their brightness, without being absolutely lost to view. The earliest observed example of this class is o Ceti, called also Stella Mira, or the wonderful star, situated in the neck of the Whale. It was first particularly remarked by Fabricius, August 13, 1596, when it appeared as a star of the third magnitude, but before the end of the year it had retreated entirely from observation. Holward remarked it again in 1637, after which it disappeared for nine months, when he again saw it. The following are now its general phases, which are gone through in 331 days, 15 hours, and 7 minutes. When at the greatest brightness, it is equal to a star of the second magnitude, and remains so for about a fortnight. It then decreases during three months, passes entirely out of sight, con tinues invisible about five months, again comes into view, increases during three months, when it attains once more its maximum lustre. It does not always, however, return to the same degree of brightness, or increase and diminish by the same gradations, or in variably remain invisible the same length of time. For the four years between October, 1672, and December, 1676, it was never seen at all, though Hevelius searched that part of the heavens diligently for it. On the other hand, it was unusually bright October 5, 1839, as observed by Argelander. The relative posi tion of Stella Mira is shewn in the diagram. Algol, the name of the star ft in Perseus, in the head of Medusa, is another remarkable instance of stellar mutation. It varies from the second to the foui-th degree of magnitude. This was determined by Maraldi in 1694 ; but Mr. Goodricke of York, in 1782, and about the same time Palitzch, near Dresden, first accu rately fixed the period of its changes. The star goes through its variations in a remarkably short space of time: it continues at its brightest two days and four teen hours. Then its splendour suddenly begins to diminish, and in three hours and a half it is reduced to its minimum. Its feeblest lustre lasts but little more than fifteen minutes. It then begins to increase, and in three hours and a half more, it is restored to its usual bright ness. Its full period is therefore 2 days, 20 hours, and 48 minutes. The remarkable law of variation to which this star is subject suggested to Goodricke the idea of some opaque body revolving around it, which, interposing between the earth and the star, cuts off a portion of its light. Algol may be seen on any fine evening from August to May, as it continues above the horizon twenty hours out of the twenty-four. With Algenib in the side of Perseus, and Almaak in the foot of Andromeda, it forms a triangle, with the open part towards Cassiopeia. % Cygni was ascertained to be variable, and its period determined by Kirch in 1686. NEW, VARIABLE, AND COMPOUND STARS. 171 It changes from the sixth to the eleventh degree of magnitude, and consequently at its brightest is only visible to the naked eye under favourable circumstances. Halley observes respecting it : — " We watched, as the absence of the moon and the clearness of the weather would permit, to catch the first beginning of its appearance in a six-foot tube : that, bearing a very great aperture, discovers most minute stars. On June the 15th last (1715), it was first perceived like one of the very least telescopical stars ; but in the rest of that month, and in July, it gradually increased, so as to become, in August, visible to the naked eye, and so it continued all the month of September. After that, it again died away by degrees, and on the 8th of December, at night, was scarcely discernible by the tube, and, as near as could be guessed, equal to what it was at its first appearance on June 15; so that this year it has been seen, in all, near six months, which is but little less than half its period, and the middle, and consequently the greatest brightness falls about the 10th of September." Its maximum brightness, however, does not seem to be uniform, as, according to Cassini, it was scarcely perceptible in the years 1699, 1700, 1701, at those periods when it ought to have been most conspicuous. Its cycle consists of 396 days, 21 hours. The most remarkable of the versatile stars in our hemisphere are stated in the following table, with their changes of magnitude, and periods of variation : — Stars. Periods of Variation. Changes of Magnitude. Authority. o Ceti (Mira) 331 days 15 hours 7 min. '2 to O Herschel, W. j8 Persei (Algol) 2 20 48 2 to 4 Goodricke. i\ Antinoi 7 4 15 3 to 5 Pigot. X Cygni 396 21 0 6 to 10 y Hydra* 490 0 0 3 to 1O ^ Leonis Several years 6 to 0 K Sagittarii Ditto 3 to 6 18 Leonis 311 23 0 5 to 10 8 Cephei 5 8 30 3 to 5 Goodricke and Pigot. £ Lyra (Sheliak) 6 10 34 3 to 5 Goodricke and others. a Herculis (Ras Algati) 60 6 O 3 to 4 Herschel, W. There are altogether nearly forty stars ascertained to be variable, and others suspected to belong to the class. Various conjectures have been hazarded to account for these cases of periodic stellar change. If we suppose the varying brightness of the bodies in question to be caused by varying distance, the same hypothesis as that which has been mentioned in connection with the temporary stars, it is singular that their position should be wholly unaltered during their respective changes. This appears fatal to the idea of orbital motion being the cause of their versatile appearance. Another surmise is, that dark bodies revolve around these stars, which, periodically intervening between them and us, temporarily cut off their light. Mr. Goodricke proposed this theory respecting the star Algol; but it is open to the objection that it requires us to assign a magnitude to the revolving body in relation to that which must be deemed its primary, which is out of all proportion to that which we are led to believe belongs to dependent orbs. The subservient bodies in our system are immensely inferior to their primary, the sun, and owing to this, to a distant observer of our part of the universe, the transit of the mighty globe of Jupiter across the sun's disk would produce no perceptible effect. Our knowledge of planetary motion is also adverse to that rigorous uniformity which is so marked a feature of the stellar changes. It may appear a gratuitous assumption to take the solar system as a miniature picture of others ; but we can only reason concerning what we know not from what we 172 SCENERY OF THE HEAVENS. know. Minute white specks appear in the neighbourhood of the stars, y Hydrae, * Gemiuorum, and « Ursae, which in all likelihood are their encircling planets — tributary companions — plainly and vastly inferior, according to the analogy of subservient bodies in our system. Their intervention would have no perceptible effect upon the appearance of their primaries to our vision. The most probable hypothesis that has yet been proposed to account for the examples before us of stellar changeableness is that of axical rotation. The variable stars are supposed to have parts of their surface less luminous than the rest, which when presented to us in the course of rotation produce the periodical decay of light, and absolute invisibility observable. A variety of circum stances occur to favour this idea. Rotation upon an axis is a law to which every orb is subject, with which we are sufficiently acquainted — as the sun, the planets, and their satellites. The greatest uniformity marks the execution of the law, and in this it differs from translation in space. The planets travel in irregular paths and with varying velocities in their orbits, but their axical motion is uniform. If, therefore, one of the hemispheres of a rotating body within the sphere of vision should be less luminous than the other, periods of decay, obscurity, revival, and vivacity, would be exhibited, of uniform occurrence and duration. Now, those who have paid most attention to solar phenomena are of opinion, that besides the sun having variable spots upon his disk, which at times have been so numerous and extensive as to impair his orb, there is reason to believe the illuminating power of his two hemispheres to be unequal, one being much fainter than the other. We may not be sensible of this, because, comparatively situated in immediate vicinity to his effulgence ; but, removed to a vast remoteness, his rotatory motion might constitute him sensibly a variable star to us. Herschel remarks : " The rotary motion of stars upon their axes is a capital feature in their resemblance to the sun. It appears to me now, that we cannot refuse to admit such a motion, and that indeed it may be as evidently proved as the diurnal motion of the earth. Dark spots, or large portions of the surface less luminous than the rest, turned alternately in certain directions either towards or from us, will account for all the phenomena of periodical changes in the lustre of the stars so satisfactorily, that we certainly need not look out for any other cause." We now proceed to notice the Multiple stars — a class unknown until a very recent date. Soon after the application of the telescope to the heavens, it was perceived that some of those brilliant points, which appear single stars to the naked eye, are in reality stellar combinations comprising two or more individuals. But little attention, however, was paid to them, and no suspicion entertained of their numerical amount. Dr. Hook, referring to y Arietis, states : " Of this kind, the most remarkable is the star in the left horn of Aries, which, whilst I was observing the comet which appeared in the year 1664, and followed till he passed by this star, I took notice that it consisted of two small stars very near together ; a like instance to which I have not else met with in all the heavens." It was reserved for the elder Herschel to detect the richness of the mine, and to take pre cedence in bringing some of its treasures to light. A catalogue of five hundred stars, apparently single, but in fact binary, was produced by this distinguished observer, and presented to the Royal Society ; and, when he ceased from his labours, his mantle fell upon successors worthy to receive it. The list of conjoined bodies, whose positions and relative distances have been accurately determined, now includes a number which is five or six times greater than that which appears in the general stellar catalogue of the ancient observers. Sir James South and Sir John Herschel produced a catalogue of 380 multiple stars in the year 1824, as the result of their joint labours. This was followed by one of 480 from South, and another of 3300 from Herschel — the fruits of solitary observation. M. Struve, of Dorpat, also has registered the data of 3000. These are all included in the NEW, VARIABLE, AND COMPOUND STARS. 173 northern hemisphere, and within 15° south of the equator. From the southern heavens an equally plenteous harvest may be gathered, of which Mr. Dunlop's catalogue of 250, observed at Paramatta, may be regarded as the first-fruits. Upon the whole, the number of stars whose multiple character and respective positions have been determined, cannot be rated at less than 6000. Of these the most numerous are twin-stars, or binary systems. Some of the more remarkable specimens are Castor, 77 Coronas, Rigel, Polaris, Mirac or £ Bootis, y Leonis, y Virginis, £ Ursae Majoris, a Herculis, 36 Andromedte, \ Ophiuchi, and TT Aquike. Of all the binary stars in the heavens, Castor is the largest and the finest ; the one also which has been the longest observed. Its structure and position were recorded by Pound in 1718, by Bradley and Maskelyne in 1759, and by Herschel in 1799 ; and, in the present day, it has been closely and perseveringly examined by Sir John Herschel, Struve, and Sir James South. Castor is a Geminorum, one of the bright stars in castor. the head of the Twins, the most northerly of the two, and is easily separated by a moderately good telescope. Its constituents are of the third and fourth magnitude, at present about 3" apart. The diagram shows the pair which now make an angle with Pollux, the other principal star in Gemini. But in Bradley's time the position was diiferent, as appears from a memorandum of one of his observations : — " Double star Castor. No change of position of the two stars : the line joining them at all times of the year parallel to the line joining Castor and Pollux in the heavens seen by the naked eye." Sir John Herschel speaks of this object as that whose unequivocal angular motion first impressed on his father's mind a full conviction of the reality of his long-cherished views on the subject of the binary stars, rj Coronae, halfway between the Northern Crown and the club of Bootes, is a delicate double star, not to be seen but under favourable circum stances, requiring the most powerful and perfect instruments. Its compound character was discovered by Herschel in 1781, since which time its constituents have gone through more than a complete revolution, which renders it the most remarkable binary star known. Rigel, the well-known star in the foot of Orion, consists of one large and brilliant with a minute companion. The attendant point was seen by Herschel with a power of 227, but has been reached by one of Dollond's two-foot telescopes with a power of 70. Po laris, the pole star, is resolved into two of very unequal size, the smaller appearing a mere point in comparison with its companion. Mirac, or e Bootis, about 10° north-east of Arcturus, is one of the loveliest objects in the heavens, on account of the contrasted colours of the two stars composing it. It requires a power of 200 distinctly to define the pair, y Leonis, about 7-|° north-east of Regulus, is another striking example of a double star. Besides stellar pairs, there are many instances of triple combination, of points apparently individual resolving into three distinct bodies when examined by an instrument of high power. An object of this kind is in the constellation Monocerotis, or the Rigel. i Bootis. y Leonis. 174 SCENERY OP THE HEAVENS. Unicorn — a star in the right fore-foot, which is resolved at first into two ; but one of these, on minute inspection, is found to be double. Herschel, who discovered this triplicate in 1781, pronounced it one of the most beautiful sights in the heavens. £ Cancri, apparently a single star of the sixth magnitude, is another example of a ternary system, separating into three of unequal size. £ Librae is also treble, as well as y Andromedoe, ^ Cassiopeiae, and 12 Lyncis. Eleven sets of bright triple stars, conjunctions of three bodies, are specified by Struve, in a very small space of the heavens. Combinations of four stars, constituting a quadruple scheme, composed of two double, have also been detected. /3 Lyrae, 7r2 Canis Majoris, 8 Lacertae, and e Lyrae are examples. The latter object the naked eye discerns as a star of the fourth magnitude, about 1^° from Vega, upon the frame of the Lyre. With slight instrumental aid it separates readily into two well-defined stars, distinctly apart, and each of these two becomes binary under a higher power. There are still more extraordinary combinations than the preceding, or quintuple and sextuple stars. Thus 6 Orionis, the trapezium, in the I! nebula, the first object upon which Herschel turned his mighty telescope, appears as a star of the third magnitude to the naked eye. It was so classed by Ptolemy and Tycho Brahe, but has long been known to be quadruple. Struve has however announced it to be quintuple, that is, when thoroughly examined, it consists of five constituent bodies so closely wedged as to appear an individual object. The phenomena of the multiple stars have already led to some interesting results. The Newtonian law of gravitation has by their means been opened to our view, operating in the far distant realms of the universe. When these proximate bodies were first disco vered, it was not suspected that any physical connexion subsisted between them — any real contiguity. The proximity was supposed to be simply optical. It was imagined, that one star lying at a remote distance behind another, and seen in nearly the same visual line, produced the appearance of a double star, as described in the diagram. In some instances this is undoubtedly the case ; and, while the prevalence of the binary arrangement was limited to a few specimens, the solution was satisfac tory. But the heavens are so thickly sprinkled with double stars, as to render it in the highest degree improbable that their occurrence is merely the acci dental effect of two stars separated by a wide interval, lying out in space in the same direction. The argument adopted has been illustrated in the follow ing manner. If we suppose a number of peas to be thrown at random on a chess-board, we should certainly expect to find them occupying irregular or random positions. If, contrary to this, they were, in far more than average numbers, found to be arranged in pairs on each square, the rational inference would be, that here there was no random scattering. The excessive preva lence of the binary arrangement would indicate forethought, design, and system. This is the reasoning of Dr. Nichol, the force of which is obvious. Hence, when we find between the pole and 15° south of the equator, 653 cases of conjunction, in which the bodies are not separated by the finest telescope from each other by more than the apparent diameter of Jupiter, and 612 cases of a lesser star associated with a greater, we are led to infer the real and designed proximity of these bodies. The principle now adverted to, led Herschel to NEW, VARIABLE, AND COMPOUND STARS. 175 1719 1779 1802 Position of the two stars of Castor. Position of the two stars of -y Virginis. the conclusion that casual situations will not account for these multiplied phenomena ; that consequently their existence must be owing to some general law of nature ; and as the mutual gravitation of bodies toward each other is quite sufficient to account for the union of two stars, he felt autho rised to ascribe such com binations to that principle. This reasoning has been emphatically confirmed by physical facts. The conclusion has 1833 i&sj, 485? 1836 been established beyond all doubt, that the multiple stars are made up of bodies in real association — phy sically connected. The constituents of a double star, closely watched through a series of years, are found to change their relative position, and to repeat the same cycle of change, indicating their systematic union under control of the law of gravitation. The diagram exhibits the observed positions of the two stars of Castor, of y Virginis, and of £ Ursae Majoris, at the respective times named. Here we have unquestionable signs of orbital motion, real JB2SA £&&& 1836"* binai>y S^StemS °f SUnS revolving around suns, the smaller around the greater, or both about a Position of the two stars off Ursae Majoris. Common Centre of gravity. One has accomplished a complete revolution, 77 Corona?, since observation was first directed to it ; and, from the progress already made by others, their times of revolution have been estimated as follows : — 1781 1809 Star's Name. f Herculis 7? Coronas f Cancri | Ursae Majoris co Leonis | Bobtis 5 Cygni 7 Virginis Castor ff Coronae Period in Years. 31 43 58 58 82 117 178 182 - 252 - 608 By whom computed. Madler. Ditto. Ditto. Savary. Madler. Sir J. Herschel. Hind. Sir J. Herschel. Ditto. Madler. In consequence of revolution, the apparent distance between the constituents of a double star varies remarkably. Thus the two stars of y Virginis have apparently approached 176 SCENERY OF THE HEAVENS. each other, and have become so close as to present the appearance of a single star to the telescope, their respective motions again opening as it were a breach between them. The constituents of Castor now appear to be closing. " This star," says Sir John Herschel, " seems on the point of undergoing, within the ensuing twenty-four years, a remarkable change, similar to that of which y Virginis has already furnished a striking instance, during the last century, and passing from a distinct double star of the second class to a close one of the first, and ultimately to one of extreme closeness and difBculty, such as only the very finest telescopes, with all the improvements we may expect in them, will be capable of showing otherwise than single." In the following years the distances of the constituents of Castor were as follows : — 1845 - - 3'' -85 I 1854 - - 1" '36 1848 - -3-37 1850 - -2-91 1852 - -2-18 1855 - - 0 -93 1856 - -0-68 "We have thus seen suns in motion around each other — or around some intervening point, in the case of quadruple and quintuple stars — as decisively evidenced by observed pheno mena, as the translation of the distant planets of our system around the central luminary. It required the most acute geometricians to resolve the well-known problem of three bodies, and it may be quite beyond our mathematics to determine the curves described by con nected suns with attendant planets acting and reacting upon each other ; but the fact of the stellar universe being the scene of activities, incessant, complex, yet nicely balanced and harmonised, is clearly before us. The contrasted colour of the multiple stars, the rich and varied hues with which they shine, is one of their most striking peculiarities. The stars visible to the naked eye, differ in the tints which they display. This, though very apparent, is not so clearly remarked in our own country by the unaided vision, owing to the general haziness of the atmosphere, as in other parts of the globe. But if we were encamped at night upon the plains of Syria, or on those of High Asia, the greatest projection upon the surface of our planet, where the firmament is displayed with greater clearness through the rarity of the circumambient air, the diverse colouring of the stellar light would be at once observed. Sirius, whose advance to the field of view, on directing a telescope to it, has been likened to the dawn of the morning, is so refulgent that for a time it has been found impossible to endure it, is brilliantly white. There has been some extraordinary changes in the history of this splendid object, for Sirius, now white, was known to the ancients as a red star, and is so characterised by Ptolemy and Seneca. This is not a solitary phenomenon, but one upon which it is quite useless to speculate. Within the last half century y Leonis and y Delphini have very perceptibly changed colour. Lyra, Spica Virginis, Bellatrix, Altair, and Vega are white stars. Procyon and Capella are orange. Al- debaran, Antares, Arcturus, Pollux, and Betelguese are red. The remark has been made by Struve, and it is corsoborated by others, that Herschel assigns to many of the stars a redder tinge than has been verified, arising perhaps from some optical peculiarity, or instrumental defect. It is well known that some persons are unable to discriminate colours correctly, and to certain colours others are totally insensible. The eminent philosopher Dalton belonged to the latter class. He saw no difference between red and green, so that he thought the face of a leaf of laurel a good match to a stick of red sealing-wax. Dugald Stewart also laboured under the same defect. "While in many cases the constituents of a binary or multiple system are of the same complexion, and of equal intensity, in other instances, there is a striking diversity as to both. r NKW, VAK1ABLE, AND COMPOUND STARS. 177 Among the binary stars catalogued by Struve, the following summary of 596 is given by him : Pairs of the same colour and intensity ... 375. Pairs of the same colour, but of different intensity - 101. Pairs of totally different colours .... 120. The white stars in the multiple systems are supposed to be 2£ times more numerous than the red, and the red twice as numerous as the blue. While insulated stars of a red colour as deep as blood are common in the heavens, and also white and yellow ones, it is a remarkable fact, that no specimen of an insulated blue, green, or violet-coloured star, has yet been found, though these occur in the binary and ternary systems. Struve furnishes the following statement of coloured primaries and blue attendants : — Pairs consisting of a blue with a white principal star - - 53. with a light yellow .... 52. with a yellow or red ... 52. with a green - .... 16. The imagination is apt to run riot, in endeavouring to picture the effect of this variety of colour, to a planetary attendant of one of the suns in a binary or tertiary system. " It may be more easily suggested in words," remarks Sir John Herschel, " than conceived, what variety of illumination two suns — a red and a green, or a yellow and a blue one — must afford to a planet circulating about either ; and what charming contrasts and grateful vicissitudes — a red and a green day, for instance, alternating with a white one and with darkness — might arise from the presence or absence of one or other, or both above the horizon." Here we have another example of that beautiful variety combined with evidences of sameness which we encounter in every region of physical nature, and which proclaim its far distant worlds to be the architecture of one infinitely potent and fertile Mind. While the double stars are governed by the same centrifugal and centripetal forces which maintain in harmony our planetary system, they display that diversity of operation in their various hues which is stamped in other forms upon the solar universe. From the preceding statements it is clear, as has been previously observed, that the common term, fixed stars, is not rigidly applicable to the bodies so denominated. Orbital revolution is not only displayed by the constituents of the multiple stars, but there are observed instances of a proper motion in space common to the constituents of each. Thus the two stars composing 61 Cygni, have preserved nearly the same distance from each other for fifty years or more, but their common location in the heavens has been altered in that time through an extent of 4''23. The annual proper motion of this double star in right ascension is 5"'46 of space; and in declination 3"-19. The estimated velocity with which it journeys through the vastness of space is supposed to exceed that of the planet Mercury. The two stars, a Ophiuchi and 30 Scorpii, which are 13' apart from each other in space, and which are not orbs revolving around each other, are yet moving along together through the universe, leaving the neighbouring stars behind them. The triple star, p Cassiopeia, has a rapid course through space, at the rate of not less than 125,000 miles an hour, and Arcturus has also a considerable proper motion. The change of place in these stars requires perfect instruments, and a lapse of years for their observation ; but a real movement of great magnitude is indicated, of which we should be sensible if we were nearer neighbours to them. In the sixteenth century, Jordano Bruno, an Italian, maintained that we are not warranted in supposing the stars to be all fixed in relation to each other, since their distance from the earth is so immense as to render their motions insensible to us ; and he remarked that it could only be decided after a long course of observation, whether they revolved around each other, or what other 178 SCENERY OF THE HEAVENS. movements they might have. This bold and original thinker suffered death at Eome, for apostatising from the Komish church ; but it is believed that his rebellion against the physics of Aristotle contributed to his committal to the flames. " This sentence," said he, on being condemned, " pronounced in the name of a God of mercy, terrifies you more than it does me." Hooke, our own countryman, in the following century, surmised the improbability of the stars being absolutely fixed with respect to each other, and suggested that not only might these bodies be in a state of continual motion, but the whole solar system likewise. But Halley is the first person who, from observation, suspected the proper motion of the stars. In a paper of the year 1718, he stated, that since the days of the Alexandrian astronomers, the stars Aldebaran, Arcturus, and Sinus, must have slowly advanced to the south. A few years later, J. Cassini demonstrated, by the most conclusive evidence, that Arcturus had sensibly shifted in latitude since the time of Tycho Brahe. Bradley soon afterwards remarked, that the apparent motions of the stars might arise either from a movement of the solar system in space, or from a real change in the positions of the stars themselves ; but he avowed the opinion, that many ages must elapse before it would be possible to come to a definite conclusion on the subject. In 1750, the remarkable " Theory of the Universe," published by Wright, assumed the motion of the solar system in space, as well as that of all the stars of the firmament. At last, in 1783, Herschel addressed himself to the resolution of the great problem, by forming a catalogue of stars situated in all parts of the heavens, in which an appreciable amount of proper motion had been detected and measured. He justly reasoned, that in case this apparent motion of the stars could be attributed to the movement of the solar system through space, a close scrutiny of the directions in which the stars appear to move, would indicate the direction in which the sun, with its train of planets, is moving. In illustration of the principle of investigation, it has been aptly remarked, that in the instance of a person travelling on a railway, in a direct line through a forest, as he advances, the trees towards which he is moving will appear to open out or separate from each other, while those left behind will appear to close up. " If, then, the astronomer, borne along by the movement of the sun through the vast forest of stars by which he is surrounded, desires to ascertain the direction in which he is progressing, let him search the heavens until he finds a point where the stars seem to be increasing their distance from each other. Should he find such a point, let him confirm his suspicions by looking in the direction precisely opposite, and in case he finds the stars located in this region closing up on each other, he may fairly conclude that he has found the direction in which he is moving, and a rigid coincidence of all the phenomena wotild demonstrate the accuracy of his conclusions." After an extended examination of the subject, Herschel announced his belief that a part of the proper motion of the stars must be attributed to the effect of systematic parallax, or to the movement of the solar system itself ; and that this movement is directed towards a point in the heavens somewhat to the north of the star y Hercules. This theory was not supposed in general by the astronomers of the day to be founded on well-determined observations. It was received, therefore, with hesitation and doubt ; it fell into disrepute ; and Herschel died before any confirmation of it had been obtained. But the recent researches of Argelander, Lundahl, Otto Struve, and Peters, on the stars of the northern hemisphere, combined with those of Mr Galloway on the stars of the southern sky, have demonstrated, in the most undeniable manner, not only the fact of the solar motion, but its direction, in close agreement with Herschel's announcement, and its rate. The results of perfectly independent observations have been thus summed up by the elder Struve : — " The motion of the solar system in space is directed to a point in the celestial sphere, situated on the right line, which joins the two stars of the third magnitude, ». and /^ Hercules, at a quarter of the apparent distance between these stars, measured from *> NEW, VARIABLE, AND COMPOUND STARS. 179 Hercules. The velocity of this motion is such, that the sun, with the whole cortege of bodies depending on him, advances annually in the direction indicated, through a space equal to 1'623 radii of the terrestrial orbit, or 154 millions of miles." But though advancing towards a determinate point in the heavens, it would be inconsistent mth analogy, and utterly incompatible with the principle of gravitation, to suppose our system to be continuously moving towards one and the same point. All the other celestial move ments are curvilinear or orbital, instead of right lines. It can scarcely, therefore, be doubted, that the apex of the solar motion slowly shifts its position in the sphere ; and that the sun, with the planetary and cometary system, is revolving round some centre in the visible heavens, which is probably a kind of grand pivot round which all the stars of our firmament describe immense orbits. M. Madler has thrown out the surmise, that this common centre lies in the Pleiades ; and that the star Alcyone in that group is the central sun. But such speculations are premature, being far in advance of practical astronomy, however probable the suppositions upon which they are based. 180 SCENERY OF THE HEAVENS. CHAPTER X. STAR-SYSTEMS. — NEBULA. AR more astonishing than any of the details upon which we have hitherto dwelt, are those relating to the class of celestial objects we have now to consider, the investigation of which is at present the highest branch of practical astronomy. In directing our attention to them, we leave what may compa ratively be called home regions, strange as the phrase appears, when we recollect the distance intervening between us and the nearest of the stars. But such language is strictly appropriate with reference to the stars visible to the naked eye, and reached by ordinary telescopic aid. They form our firmament or cluster, near the centre of which the solar system is supposed to be situated. Yet besides this province with which we are connected, incalculably vast as it is, perfectly inestimable both in length, breadth, depth, and height, there are other provinces within view, equally as capacious, distinct firmaments or clusters, scattered through those territories of the universe that are accessible to our gaze; and could we be removed to any of them, the whole of that great scheme of existence apparently circum scribed by the Milky Way, might seem compressed into a small globular patch in space, or sprawling spot, only to a trifling extent bedimming the azure of the heavens — the aspect presented by these star-systems, clusters, or nebulae to ourselves. It is a reasonable supposition that stars which are classed as belonging to the inferior orders of magnitude, only appear to be so generally, because of their greater distance. Now it is observable, that the most brilliant, or those of the first, second, and third magnitudes, are pretty evenly distributed over the surface of the heavens ; but those of the fourth, fifth, and sixth magnitudes appear in crowds towards the margin of the Milky Way, while that remarkable zone of light is plainly demonstrated to be an enormous aggregation of minute stellar objects, very expressively characterised as "star-dust." Hence the suspicion naturally arose, that there was some connection between the Galactic circle and the other portions of the heavens, so that the whole might form one great system. The extensive celestial surveys laboriously executed by Herschel — his telescopic gauging or sounding of the sphere — contributed to confirm this idea ; and all subsequent investiga tions, as those of Sir John Herschel in the southern hemisphere, have tended to the same result. So far, therefore, from being fortuitously dispersed through space, as was once supposed, the stars forming our firmament are definitely arranged ; and the particular shape of the whole mass or cluster, as it would appear to spectators in remote clusters, has been examined and approximately sketched. The whole visible creation of stars is conceived to form a stratum or layer, extending to an immense but limited distance, and thin, in proportion to the length and breadth. If our position therefore is towards the central regions of this stratum, we shall obviously see a great gathering of stars, agglomerated into one mass, looking towards the elongations, forming an appearance answerable to that of the Milky Way ; but looking towards either of the surfaces of the stratum, we shall see a far lesser number of stars, appearing also more distinct and scattered, answering to the aspect of the other parts of the heavens. Supposing likewise the stratum, on one side, to be split down the middle, the appearance in that direction will be that of the Milky Way, STAR-SYSTEMS — NEBULA. 181 divided through a certain extent into two branches. The diagram may help to illustrate this view of the architecture of the visible stellar universe, the small circle indicating the place of the solar system in it. It was the idea of Herschel, that the thickness and greatest elongation of this bed of stars might be equal respectively to eight and nine hundred times the distance of the nearest of the fixed stars from our system ; and that our place in it is eccentric in relation both to the surfaces and the extremities. We thus pass from the grand idea of an individual sun or star, with attendant planets, forming a solar system, to the incomparably grander conception of a vast mass, cluster, or universe of solar systems, many perhaps surpassing our own in magnitude, and doubtless held together in definite arrangement and unbroken harmony by the bond of gravitation. Yet this stellar scheme, mighty as are its dimensions, is but a sample of the contents of celestial space — a single member in a numerous family of similar sidereal assemblages, within hail of the modern telescope. These remote groups, "island universes" as the Germans call them, a few of which may be detected by the naked eye, are generally spoken of collectively as nebulce, from their cloud-like appearance, a denomination applied to them long before their real character was known or suspected. They vary considerably in shape, size, and luminosity ; and occur in numbers, which every improvement of the telescope increases. In Halley's time the whole number known amounted to six ; but he naively remarked, "there are undoubtedly more which have not yet come to our knowledge.** Messier, the " comet-ferret," was the first who paid particular attention to these objects. While looking for Halley's comet, in 1758, whose return was then expected, he observed in the neighbourhood of ? Tauri a whitish light, elongated like the flame of a taper. This led to the production of his list of these objects, containing a hundred and three, the result of his own personal observation. It appeared in the Connaissance des Temps, for the year 1784, an astronomical almanac published by the French Board of Longitude. Herschel discovered upwards of two thousand more, whose places were determined and catalogued by his sister. Sir John Herschel commenced in 1825 and finished in 1833 the most complete catalogue of nebulae, containing his father's results, and five hundred additional objects, the fruits of his own observation. " I have already determined," he remarks, " with as much accuracy as the nature of such observations permits, the places ; and obtained sufficient descriptions of the physical peculiarities, of between two and three thousand of these wonderful objects — a great part of them by many repeated observations, and made careful drawings of the most remarkable for their shape, size, or structure. 182 SCENERY OF THE HEAVENS. Among these are objects so surprising, that I shall earnestly desire to see my observations verified by the powerful instruments (if sufficiently so) which are now become common in the hands of observers." More than 4000 have now been observed and catalogued. Taking a favourable night in spring or autumn, a practised eye may discern a feeble speck between « and ? Herculis, two stars of the third magnitude north and south of each other, in that constellation, « being about 22° nearly due west of Vega. This speck is the thirteenth nebula of Messier's list, described by him as nebuleuse sans etoiles. It was observed by Halley in 1714, who remarks, " This is but a little patch, but it shows itself to the naked eye when the sky is serene, and the moon absent." Employing a common telescope, it assumes the appearance of a small and faint cometary body, of a globular shape ; but using an instrument of first-rate power, it resolves into a mass of stars, whose number must be enormous, but apparently so closely wedged together, owing to their remoteness, as to present the little indivisible streak of light which is scarcely perceptible Nebula in Hercules. without optical aid. The cut represents this object as seen in a reflector of 18 inches aperture, and 20 feet focal length. It is impossible, says an assiduous observer, to give a fitting representation of this magnificent cluster. Perhaps no one ever saw it for the first time through a large telescope, without uttering a shout of wonder. The heavens, as seen from a sun of this astral system, near its centre, must present a most gorgeous appearance. In all directions, innumerable stars of all magnitudes will be seen, forming a spectacle such as would be presented by our heavens, in case the Milky Way were expanded to cover the entire celestial sphere. Such spherical stellar clusters are common, the individuals of each being no doubt separated from one another by as wide a gulf as that which exists between our sun and the nearest star, their apparent contiguity and compression to us arising from their immeasurable distance. It is inferred from the appearance presented by many clusters, that the components of each are bound together by mutual relationships, and constitute a particular assemblage of stars governed by internal laws peculiar to itself, though corresponding generally with those which prevail in other sidereal systems. The common occurrence of the globular shape, and of great central condensation, the light there running up into an unbroken blaze, may perhaps be accepted as evidence of the attraction of gravitation. It is striking to catch a glimpse of a law with which we are so familiar — the law that STAR-SYSTEMS. — NEBULAE. 183 unites the atoms that compose the earth, forms every rain-drop, and moulds the tear that trickles down the cheek of sorrow — in prevailing operation millions of leagues away from our terrestrial residence, binding together in spherical masses whole sidereal systems. Such a fact, however, commonly suggests no further remark than that the laws of nature everywhere prevail, and with this, thought in general ends. But "what," says Paley, " do we mean by the laws of nature, or by any law ? Effects are produced by power, not by laws. A law cannot execute itself. A law refers us to an agent." An irresistible conviction is forced upon us, of the universal agency, and, consequently, the omnipresence of one Lawgiver, by the universal presence and execution of kindred laws ; and confessedly incomprehensible as is the modus of His operation, it would be not more irreligious to stumble at this than unphilosophical, considering the immense amount of things of which we have certain evidence that they are, without having any glimpse as to how they are. We cannot at all understand the physical agency of the Deity ; but paying deference to the strong facts of nature, we are led to the conclusion that He "Lives through all life, extends through all extent, Spreads undivided, operates unspent." The conclusions are marvellous that are forced upon us by these objects. Here we have firmaments or clusters, insulated in space, each constituting a sidereal family equal to that to which our sun belongs. " It would be a vain task," says the highest authority upon this subject, " to attempt to count the stars in one of these globular clusters. They are not to be reckoned by hundreds ; and on a rough calculation, grounded on the apparent intervals between them at the borders (where they are seen not projected on each other), and the angular diameter of the whole group, it would appear that many clusters of this description must contain, at least, ten or twenty thousand stars, compacted and wedged together in a round space, whose angular diameter does not exceed eight or ten minutes ; that is to say, in an area not more than a tenth part of that covered by the moon. Perhaps it may be thought to savour of the gigantesque to look upon the individuals of such a group of stars like our own, and their mutual distances, as equal to those which separate our sun from the nearest fixed star : yet when we consider that their united lustre affects the eye with a less impression of light than a star of the fifth or sixth magnitude (for the largest of these clusters is barely visible 'to the naked eye), the idea we are thus compelled to form of their* dis ta nee from us may render even such an estimate of their dimensions familiar to our imagination ; at all events^ we can hardly look upon a group thus insulated, in seipso totus, teres, atque rotundus, as not forming a system of a peculiar and definite character." But the globular form, though common, is by no means unvarying. There are oval shapes, while some are of very irregular outline, and present a fantastic appearance. The 30 Doradus, as sketched at Paramatta by Mr Dunlop, and examined by Sir John Herschel at the Cape of Good Hope, resembles a number of loops, or a kind of " true lover's knot " formed by a bunch of ribbons. An angular-shaped mass appears in the Twins, on a line drawn from Pollux to the middle of Orion's belt, discovered by Herschel in 1783. Another, in the form of a distant flight of wild-fowl, discovered by Kirch in 1681, is on the shield which Hevelius framed among the stars in honour of John Sobieski, the deliverer of Vienna from the Turks. One of the most conspicuous of these objects, called the " transcendently beautiful queen of the nebulae," and the oldest known, appears below the girdle of Andromeda. It is visible to the naked eye in the absence of the moon, and has often been mistaken for a 181 SCENERY OP THE HEAVENS. comet. A notice of it occurs as early as the commencement of the tenth century. The first telescopic view was obtained by Simon Marius, loth December 1612, who compared it to a candle shining through a horn ; that is, a diluted light, increasing in density towards Nebula in Andromeda. a centre. This nebula is of lenticular shape, and forms nearly a right-angled triangle with Almaach and Mirac, the two principal stars of Andromeda. A good eye may pick it up on a favourable night, by projecting a line from Sheratan, the second star in Aries, through Mirac, to about 4^° beyond. It is about half a degree long, and from 15' to 20' broad. Herschel believed this to be one of the nearest nebulae in the heavens, though at a distance two thousand times greater than that of Sirius. Notwithstanding the improved optical means of the moderns, it has not been resolved into stars, though no doubt can be entertained of its stellar composition. Numerous telescopic stars appear involved in the glow, but are not supposed to have any connection with it, being interposed between it a,nd our system. There are examples of nebulse presenting circular or slightly oval disks, resembling planets, but with different degrees of definition at the borders. In several instances they appear of " a fine and full blue colour, verging upon green." They are no doubt clusters of stars reduced by mutual proximity and vast distance to the form of planetary disks. Sometimes they are found combined in pairs, like the physically connected double stars ; Planetary and Double Nebula*. and if they are to be regarded as two distinct star-systems, each having its own centre of condensation, yet revolving round each other by the tie of gravitation, the imagination can scarcely realise the vastness of the idea suggested. STAR-SYSTEMS. — NEBULJ2. 185 While generally exhibiting tolerably defined shapes in the depths of space, some of the more considerable nebulas have a strangely irregular aspect and outline. This is especially the case with reference to the great nebula of Orion, one of the most extraordinary objects in the heavens, for its great extent, inequalities of light and shade, and capricious form. It occurs in the sword-handle of the figure which forms the constellation ; and a good eye may discern it without the assistance of a glass. Huygens was the first to describe this object, though Galileo is said to have observed it through his telescope. " Astronomers," says the former, " place three stars close to each other in the sword of Orion : and, when I viewed the middlemost with a telescope in the year 1656, there appeared, in the place of that one, twelve other stars ; among these, three that almost touch each other, and four more besides, appeared twinkling as through a cloud, so that the space about them seemed much brighter than the rest of the heavens, which appearing wholly blackish, by reason of the fair weather, was seen as through a certain opening, through which one had a free view into another region which was more enlightened. I have frequently observed the same appearance in the same place without any alteration ; so that it is likely that this wonder, whatever it may be in itself, has been there from all time ; but I never took notice of any thing like it among the rest of the fixed stars." This nebula, as discerned by the naked eye, exhibits an indefinite, foggy appearance. It is brighter, more diffuse and strange, when a telescope is used ; but the whole light and power of Herschel's forty- feet reflector could not resolve it into distinct stars. "This highly interesting object," he states, "engaged my attention in the beginning of the year 1774, when, viewing it with a Newtonian reflector, I made a drawing of it ; and, having from time to time reviewed it with my large instruments, it may easily be supposed that it was the very first object to which, in February 1787, I directed my forty-feet telescope. The superior light of this instrument showed it of such a magnitude and brilliancy, that, judging from these circum stances, we can hardly have a doubt of its being the nearest of all the nebulae in the heavens, and, as such, will afford us much valuable information." It seems composed of little flocky masses, or wisps of cloud, adhering to some small stars at its outskirts, and enveloping one with an atmosphere of considerable extent. " I know not," says Sir John Herschel, " how to describe it better than by comparing it to a curdling liquid, or a surface strewed over with flocks of wool, or to the breaking up of a mackerel sky, when the clouds of which it consists begin to assume a cirrous appearance. It is not very unlike the mottling of the sun's disk, only, if I may so express myself, the grain is much coarser, and the intervals darker ; and the flocculi, instead of being generally round, are drawn into little wisps. They present, however, no appearance of being composed of stars ; and their aspect is altogether different from that of the resolvable nebulae. In the latter, we fancy, by glimpses, that we see stars, or that, could we strain our sight a little more, we should see them : but the former suggests no idea of stars, but rather of some thing quite distinct from them." From a comparison of the descriptions and drawings of this object, since the time of Huygens, great alterations might be -inferred. But astrono mical delineation was not then sufficiently advanced to render the diagrams at all satis factory, nor were the instruments sufficiently powerful. The first rigidly accurate representation of it is that by Sir John Herschel, which justifies its familiar name, that of the Fish's Mouth, as it certainly resembles the head and yawning jaws of some monstrous animal, with a kind of proboscis running out from the snout. Its apparent superficial magnitude is rather more than twice that of the moon's disk. The absolute dimensions must be enormous. Such, down to a recent date, were the -only ascertained peculiarities of this wondrous mass. From the perfect irresolvableness of this and other nebulae, together with a milky appearance, it was formerly supposed that a distinction must be drawn between them and 186 SCENERY OF THE HEAVENS. those of the resolvable class. The latter, with more or less difficulty, were separated by the telescope into stars ; the former gave no indication of being similarly constituted when interrogated by the highest instrumental power. Hence arose the famous hypothesis, that a chaotic kind of material exists, occupying extensive spaces, self-luminous and phosphor escent, which presents an endless variety of contour and condensation, resembling in many instances A sheet of fog, but exhibiting in others an aggregation into spherical or oblong masses. This was conceived to furnish a key to the origin of the worlds and systems of worlds disclosed around us — to unveil, likewise, the primitive state and early history of the solar universe — diffused nebulosities having advanced gradually by the mutual attraction of their particles into dense spheroids. The theory was premature, for improved telescopic power has largely disproved its data. After looming mysteriously in the sky, the great nebula of Orion yielded to the giant instrument of Lord Rosse, and disclosed its stellar construction. The history of the event is thus given by Dr Nichol : — "About Christmas 1845, I had the pleasure of visiting Parsonstown, and saw the nebula, through that mighty tube. It was — owing to the incompleteness of the instrument and unfavourable weather — the first time that the grand telescope had been directed towards that mysterious object : and though Lord Rosse warned me that the circumstances of the moment would not permit him to regard the decision then given as final, I went in breathless interest to its inspection, Not yet the veriest trace of a star ! Looming unintelligible ae ever, there the nebula lay ; but how brilliant its brighter parts ! How much more broken the interior of its mass ! How innumerable the streamers now attached to it on every side ! How strange, especially that large horn to the north, rising in relief out of the dark skies, like a large cumulus cloud ! It was still possible, then, that the nebula might be irresolvable by the loftiest efforts of human art ; but doubt continued to remain. Why, in an inquiry like this, the concurrence of every favourable condition is needful to success, may be readily comprehended. It is its aim to discern, singly, a number of sparkling points — small as the point of a needle, and close almost as the particles of a handful of sand ; how easy, then, for any unsteadiness in the air, or any imperfection in the instrument, so far to diffuse the light of each that they would merge into each other, and thus become confounded in one mass !" Throughout the winter, the noble owner and constructer of the instrument resolved to seize every favourable opportunity to penetrate, if possible, the constitution of this wonderful object ; and at length addressed the following note to Dr Nichol: — "March 19, 1846. In accordance with my promise of communicating to you the result of our examination of Orion, I think I may safely say, that there can be little, if any, doubt as to the resolvability of the nebula. Since you left us, there was not a single night when, in absence of the moon, the air was fine enough to admit of our using more than half the magnifying power the speculum bears ; still we could plainly see that all about the trapezium is a mass of stars ; the rest of the nebula also abounding with stars and exhibiting the characteristics of resolvability strongly marked. — ROSSE." It has subsequently been shown more fully to •consist of an immense irregular assemblage of stars, which were not previously discernible for want of sufficient optical aid. Hence it is morally certain, that all these irresolvable objects are really star-systems, the -components of which are not distinguishable by reason of their remoteness, though collectively they gleam across those spaces, the magnitude of which is perfectly confounding. The different appearances presented by the same nebulae, when viewed by inferior and more powerful telescopes, is very striking. The following are examples of the same object as seen in Sir John Herschel's instruments and those of Lord Rosse. The Crab Nebula, which the right-hand figure in the cut shows with the strange appendages brought to light by the mirror of Lord Rosse, appeared to Sir John Herschel as a dull ellipse, like STAR-SYSTEMS.— NEBULAE. 187 the figure to the left. A similar transformation was effected in the case of the Dumb-bell Nebula. CRAB NEBULA. Sir John Herschel. Lord Rosse. DUMB-BELL NEBULA. Sir John Herschel. Lord Rosse. 188 SCENERY OF THE HEAVENS. The most startling shapes which have hitherto turned up are of the spiral or whirlpool form, of which the annexed representations are specimens. Spiral Ncbulaa. Two very remarkable nebulae, well known to the mariners, being visible to the naked eye, distinguish the southern firmament. They are cloudy masses of light, called the Nubecula Major and Minor, greater and lesser cloud, but familiarly referred to as the Magelknic clouds, after the navigator Magellan, who was one of their first European observers! However it may savour of the gigantesque, it is sufficiently evidenced that an area of the heavens not exceeding Tyh of the lunar diameter, contains a system of stars rivalling in number those which constitute our firmament, and appearing only as a single faint luminosity to us. Yet there are many areas so occupied. It follows therefore that our firmament is but one of a series, and probably one of the smaller chambers in the great mansion of the universe. All the stars and constellations that shine in the midnight sky, •constitute a stellar scheme which is but a unit of a countless number. As seen from the faint objects we discern in the side of Hercules and the sword-handle of Orion, our whole sphere would be compressed into a small streak of light, and appear in space like a snow- flake in our atmosphere ! We may conclude, however, that as the firmament, which the unaided eye of man surveys, is but a member of a vast family of systems which his assisted vision scans, so that family may be no more than as a drop to the ocean, a grain of sand to the mass of the globe, compared with what liea beyond the bounds of telescopic sight, hid in regions which mortal gaze will never explore or visit. Suppose we could actually travel across the space through which the terrestrial eye can penetrate, and take our station at the point which is now the limit of vision, would there not be a territory lying before us, equal to that we should have left behind, in the number, grandeur, and variety of its works ? That the Divine capability has operated no further than where a limit is put to human investigation— that the length and breadth of the Divine dominions have been STAR-SYSTEJb'S. — XEBUL.E. 189 surveyed, when we have arrived at a point which we cannot pass — it were folly and presumption to imagine. That part of space beyond which the art and genius of man fail to conduct his glance, simply reminds us that we are finite beings, and that we have reached the limit which for the present circumscribes finite powers. It is not the boundary of the Creator's workmanship, but a point of indication, that His house, to us, is, like Himself, illimitable, and that its measurement is a' task to which His infinitude alone is equal. With these notices, the view proposed to be taken of the SCENERY OF THE HEAVENS concludes. It cannot close more appropriately than with the advice to Adam, which Milton puts into the mouth of the angel : — " Yet not to earth are those bright luminaries Officious ; but to thee, earth's habitant, And for the heaven's wide circuit, let it speak The Maker's high magnificence ; who built So spacious, and his line stretched out so far, THAT MAN MAY KNOW HE DWELLS NOT IN HIS OWN ; An edifice too large for him to fill, Lodged in a small partition ; and the rest Ordained for uses to his Lord best known." APPENDIX. L ELEMENTS OF THE SOLAR SYSTEM. 1. The Sun. Mean distance, in semi-diameters of the earth, Mean distance in miles, Kotation on axis in sidereal hours, Volume, earth as 1, . . . . Mass, earth as 1, Density, earth as 1, True diameter, in diameters of the earth, True diameter in miles, Mean apparent diameter, . 23,934 95,000,000 607 h. 48m. 1,384,470 354,936 0'25 111,454 882,000 32' 02" 9 2. The Planets. Diameter in Miles. Density, Eavth as 1. Inclination of Orbit to the Ecliptic. Distance from Sun. Millions of Miles. Period of Revolution. Days. Period of Rotation. Hours. Mercury, . 3,140 1-14 7° 0'- S" 37 88 24h. 05m. 28s. Venus, . . 7,700 d-84 3 23 28 68 ?242 23. 21 0 Earth, 7,912 1-00 — 95 365 24 0 0 Mars, . 4,100 072 1 51 G 142 287 24 39 21 Planetoids . — — — • — — ' — Jupiter, 90,000 0-24 1 18 51 495 4,332 9 55 49 Saturn, 76,791 o-n 2 29 35 906 10,759 10 29 0 Uranus, 35,307 0-20 0 46 28 1822 30,687 Neptune, . 39,793 ? 0-15 1 46 59 2854 60,126 190 SCENERY OF THE HEAVENS. 3. The Planetoids. Period of Inclination of Revolution. Orbit to the Discoverers. Dates of Discovery. Days. Ecliptic. Ceres, 1681 10° 36' 30" Piazzi, . . 1801. January 1. Pallas, . 1684 34 4-2 29 Olbers, 1802. March 28. Juno, . 1592 13 3 9 Harding, . 1804. September 1. Vesta, . . 13-25 789 Olbers, 1807. March i'9. Astrsea, 1511 5 19 8 Hencke, . . 1845. December 8. Hebe, 1380 14 46 24 Hencke, 1847. July 1. Iris, . . 1347 5 27 56 Hind, n August 13. Flora, 1193 5 53 8 Hind, « October 18. Metis, . 1346 5 36 0 Graham, . 1848. April-25. Hygeia, . 2051 3 46 50 Gasparis, 1849. April 12. Parthenope, . 1402 4 36 57 Gasparis, . 1850. May 11. Victoria, . 1302 8 23 1 Hind, n September 13. Egeria, 1510 16 32 23 Gasparis, . n November 2. Irene, 1520 9 6 30 (Hind, . \ \ Gasparis . . \ 1851. May 19. n May 23. Eunomia, 1569 11 43 39 Gasparis, July 29. Psyche, . 1825 347 Gasparis, . . 1852. March 17. Thetis, 1420 5 35 25 Luther, n April 17. Melpomene, 1270 10 8 58 Hind, n June 24. Fortuna, 1393 1 32 33 Hind, w August 22. Massilia, . . 1304 0 41 9 J Gasparis . . } { Chacornac, . j n September 19. * September '20. Lutetia, 1387 3 5 21 Goldschmidt, n November 15. Calliope, . . 1812 13 45 28- Hind, n November 15. Thalia, 1556 10 13 18 Hind, n December 16. Themis, . 2H35 0 48 57 Gasparis, .. 1853. April 5. Phocea, 1358 21 35 53 Chacornac, . n April (i. Proserpina, . 1580 3 35 39 Luther, . May &. Euterpe, 1312 1 35 31 Hind, i, November 8. Bellona, . . 1638 9 22 32 Luther, 1854. March 1. I Marth, . . } it March 1. Amphitrite, . 1491 6 7 52 ] Pogson, n March 1. ( Chacornac, . } n March 2. Urania, . 1324 2 5 57 Hind, „ July 22. Euphrosyne, . 2048 26 25 12 Ferguson, n September 1. Pomona, . . 1516 5 29 14 Goldschmidt, . n October 26. Polyhymnia, . 1770 1 56 48 Chacornac, i, October 28. Circe, . . 1606 5 26 55 Chacornac, 1855. April 6. Leucothea, 1873 8 15 17 Luther, . n April 19. Atalanta, . 1665 18 42 9 Goldschmidt . October 5. Fides, 1568 3 7 10 Luther, . .. October 5. Leda, . . 1656 6 58 31 Chacornac, 18 6. January 12. Lsetitia, . 1683 10 20 50 Chacornac, February 8. Harmonia, . 1246 4 15 48 Goldschmidt, . March 1. Daphne, 1358 15 48 23 Goldschmidt, . May 22. Isis, . . 1386 8 34 39 Pogson. May 23. Ariadne, . 1191 3 28 — Pogson, . 1857. April 15. Nysa, 1599 3 53 — Goldschmidt, . May 27. Eugenia, 1617 6 35 — Goldschmidt, June 28. Hestia, . . 1406 2 18 — Pogson, August 16. Aglaia, 1793 56 — Luther, . September 15. Doris, . . 2000 6 30 — Goldschmidt, .. September 19. Pales, 1980 38- Goldschmidt, . September 19. Virginia, . . 1596 2 52 — ( Ferguson,. . I I Luther, . . > October 4. October 19. Nemausa, . — — — — Laurent, | 1858. January 22. Europa, . . — — — — Goldschmidt, February 4. Calypso, — — — — Luther, April 4. Alexandra, . — — — — Goldschmidt, September 11. PLANETS. 191 3. The Moon. Mean distance from primary, 29 '982175 times diam. terr_ equator,, above . 237,000 miles. Mean sidereal revolution, 27 '32 1661 423 solar days, or . . 27d. 7h. 43m. 11s. Mean tropical revolution, 27*321582418 s alar days, or . 27d. 7h. 43m. 4s. Mean synodical revolution, 29 '5305887215 solar days, or . 29d. 12h. 44m. 2s. Mean motion in a mean solar day, .... 13° 10 35" Inclination of orbit, ..... 5°^ 47" Inclination of axis, . ..... 1° 30' 10" Apparent diameter when nearest to us,. . . • • . 33' 31" « at mean distance, . .'''»/"• . 31' 07" n when furthest off, . . i . 29' 21" Diameter, to earth, as 1 to 3 -6655, or about . 2 160 miles. Vnlnmp Aflrtli &"DS OK THE EARTH. 209 our footpath, which had been quite hidden by the intervening mass." There is a limit, however, put to the encroachments of the glaciers. The lower extremities are gradually thawed away in the warm atmosphere of the valleys, so that though pushed forward by the weight of ice and snow accumulated at the upper extremities during the winter, there is a "bound fixed by a perpetual decree," beyond which they cannot pass. Coleridge strikingly alludes to these formations in his Hymn before Sunrise in the Vale of Chamouni ; and science will not quarrel with him for the line which expresses the optical appearance, rather than the philosophical truth. " Ye ice-falls ! ye that from the mountain's brow Adown enormous ravines slope amain — Torrents, methinks, that heard a mighty Voice, And stopp'd at once amid their maddest plunge! — Motionless torrents ! Silent cataracts ! Who made you glorious as the gates of heaven Beneath the keen full moon? Who bade the sun Clothe you with rainbows ? Who with living flowers Of loveliest blue, spread garlands at your feet? God ! let the torrents, like a shout of nations, Answer ! and let the ice-plains echo, God ! God ! sing, ye meadow-streams, with gladsome voice ! Ye pine-groves, with your soft and soul-like sounds ! And they, too, have a voice, yon piles of snow, And in their perilous fall shall thunder, God !" The glaciers exhibit a singularly diversified aspect, hues varying from the purest white to a blue and green tinge, surfaces resembling in some parts a smooth and polished mirror, and in others a sea frozen when angry and tempest-tost. But of all the phenomena exhibited by the highlands of the globe, those of the active vol canoes are the most peculiar and sublime. The term is derived from Vulcanus, the imaginary god of fire among the Romans, and is applied to those mountains which are the vents of igneous action, ejecting from their sides or summits flame, smoke, ashes, and lava streams. They are in general elevations of a conical form, terminating at the summit with a hollow, called a crater or cup from its shape. Smoke is constantly issuing from the tops of some of these mountains, but the violent paroxysms during which stones are discharged, and torrents of red-hot lava, occur only at distant and irregular intervals. The eruptions frequently issue from several openings or smaller craters, within the superior one, the number and size of which are considerably varied by eras of disturbance. These eras are generally preceded, in some instances for several weeks, by the shocks of earthquakes, or by immense columns of smoke issuing from the volcano about to exhibit explosion, often involving the neighbouring country in darkness. Sounds resembling the successive discharges of a park of artillery are then heard, followed by sudden flashes of flame, and showers of stones. A stream of lava next bursts forth from the side of the mountain, or in a great eruption from the crater, flowing in a sluggish fiery current down the declivities. After the lava ceases to flow, the volcanic ashes, composed of various materials, are thrown out of the summit in immense quantities, sufficient to cover the vicinity for miles. The products of volcanoes differ to some extent, those of America casting out water, and in some instances fish, besides the ordinary materials. It is singular, also, that in the New World, the active volcanic sites are chiefly continental, while in the Old "World they are mostly found in the islands. In both regions, however, they are almost invariably situated near the sea, or some inland collection of water. Upwards of three hundred are known to exist, distributed as follows, according to Girardin's table, which, however, is only approximative : — 210 PHYSICAL GEOGRAPHY. Europe, - on the Continent, 1. On Islands, 20 Asia and Oceania, „ 17. „ 137 Africa, „ 2. „ <) America, „ 86. „ 28 In addition to the above, Mount Erebus, on the south polar continent, is an active volcano of immense size. The mass and elevation of volcanoes seem to regulate the occurrence of eruptions, the smallest being j;he most active. Thus Stromboli, an inferior elevation, is almost always flaring as the great lighthouse of nature in the Mediterranean. Vesuvius, far less than Etna, is the most active of the two, while some of the enormous Andean cones repose for centuries. Of existing volcanic action, the most sublime and imposing example perhaps to be found in the world, is in the island of Hawaii, formerly called Owhyhee. The whole island seems to be an immense hollow cone, having an area of 4000 square miles, and attaining an elevation of 16,000 feet, the height of Mowna Roa. It forms a pyramidal chimney over a vast incandescent mass burning beneath it, and also under some part of the bed of the surrounding ocean, having numerous vents through which the furnace below commu nicates with the atmosphere above. Lord Byron and a party of officers from the Blonde frigate, with the Rev. Mr. Stewart, visited the crater of Kilauea, near the base of Mowna Roa, and witnessed a scene, says the describer, more horribly sublime than any thing he had ever imagined to exist even in the idler visions of unearthly things. Arrived at the brink of the crater, they stood looking down into a fearful gulph, fifteen hundred feet in depth, and upwards of two miles in circumference. The edge of the crater was so steep, that it seemed as if by a single leap they could plunge into the lowest abyss. Its surface had all the agitation of an ocean. Billow after billow tossed its monstrous bosom into the air, and occasionally the waves from opposite directions met with such violence as to dash the fiery spray in the concussion forty or fifty feet high. Such was the agonising struggle of the action Avithin — the appalling sounds of the conflicting elements, muttering and sigh ing, groaning and blowing, that one of the party shrunk back exclaiming: — " Call it weak ness, or whatever you please, but I cannot look again ! " About fifty cones of various height, active chimneys of volcanic fire, were counted in the abyss. Volumes of smoke and steam were ascending from these vents, but as the evening closed, fire after fire appeared glim mering through the vapour. Some of the cones were ejecting fragments of rock ; others, ashes, lava, and boiling water ; streams of fire seemed to be running among the labouring craters ; forming a scene which, in connexion with the roar of the elements bursting from their prison, reminded the party, as one of them expressed it, of the lake that burneth with fire and brimstone. To the bottom of the abyss it is well known that a Christian convert descended, and plunged a stick into the fiery deluge ! an act of female heroism to dispel the illusion of her countrymen, who were spectators at a distance, and who fancied thatPeli, the god of the Kilauea fires, would punish with instant destruction any violation of his sanctuary. One of the most tremendous volcanic eruptions ever recorded, was that which issued from the Tomboro mountain in the island of Sumbawa, for an account of which we are indebted to Sir Stamford Raffles. It began on the 5th of April, 1815, and continued with some intermissions until the June following. The sound of the explosion was heard at Ternate on the western coast of Gilolo, a distance of seven hundred and twenty geo graphical miles : and in Sumatra, which is nine hundred and seventy. In some parts of the island violent whirlwinds carried up men, horses, and cattle into the air ; the sea was covered with the trunks of trees which had been torn up ; and the ashes from the moun tain, wafted to Tara and Celebes, a distance of three hundred miles, caused a darkness in the daytime more profound than had ever been known in the darkest night. To the west 212 PHYSICAL GEOGRAPHY. but failed, owing to the cone being surrounded by deep ravines, and pronounces the ascent to the crater impossible. This is the highest of the Andean volcanoes which have recently been in an active state. If the 3932 feet of Vesuvius were planted upon the top of Etna, which has an elevation of 10,873, Cotopaxi would not be equalled in altitude by 4073 feet. Its eruptions have been upon a scale corresponding with its magnitude. In 1738 its fires ascended 2953 feet above the crater, and in 1744 its voice was heard at Honda, on the river Magdalena, a distance of nearly seven hundred miles. In 1768 the inha bitants of two neighbouring towns were obliged to use lanterns by day in the streets, owni"1 to the quantity of ashes ejected, and at two hundred miles' distance Humboldt and Bonpland heard its noises day and night, like the discharges of a buttery, during the explosion of 1803. A second line of volcanic action, upon as gigantic a scale as the preceding, commences at one of the most western points of North America, the peninsula of Alaska, in latitude 55°. It pursues a western course for about two hundred geographical miles, embracing the Aleutian isles, and reaching to the opposite coast of Kamtschatka. Throughout the whole of this tract earthquakes are of frequent occurrence, and the bed of the sea and the surface of the land are often altered by their tremendous violence. Seven active volca noes are found at the southern extremity of the peninsula of Kamtschatka, and from thence the chain trends to the Kurile isles, where nine more are known to have been in eruption. Still southerly, the line extends to the Japanese group, where there are a con siderable number, and where the disruption of the surface of the land in some districts is almost incessant, and sometimes violent. Passing the tropic of Cancer, the range embraces the Loo Choo archipelago, the Philippine and Ladrone islands, and is prolonged south to New Guinea. Here it branches off in a vast transverse line, extending on the one hand into the heart of the Pacific, and on the other through Java and Sumatra into the Bay of Bengal. A third chain traverses the whole of the southern part of the European continent, a distance of above a thousand geographical miles. It commences at the Azores, and ex tends to the Caspian Sea, having for its northern boundaries the Tyrolian and Swiss Alps, and for its southern bounds the northern kingdoms of Africa. This district has frequently been visited with earthquakes, those of Lisbon and Calabria causing the whole continent to vibrate at the shock. Etna, Vesuvius, and Stromboli are at present the chief active vents, but anciently Vesuvius was in a state of torpor, and the island of Ischia was the scene of volcanic explosion. This small spot, about eighteen miles in cir cumference, now containing a population of twenty-five thousand, was frequently abandoned by its inhabitants on account of its violent convulsions. Before the Christian era, the Erythreans, the Chalcidians, and a colony established by Hiero king of Syracuse, were successively driven from it. Ischia however sunk into repose, which has not since been disturbed, only with one exception, when Vesuvius, in the year 79, burst forth from the stillness of ages, and overwhelmed the cities of Berculaneum and Pompeii with its ashes. The eruptions of Etna are mentioned as occurring from the earliest periods to which his tory and tradition extend. Thucydides speaks of three between the colonization of Sicily by the Greeks and the commencement of the Peloponnesian war in the year B. C. 431. It was a fable of the Greek mythology, that the giant Typhos was confined beneath Sicily, his outstretched limbs extending under the Italian peninsula, and the terrible natural phenomena of the region were assigned to the struggles of the imprisoned monster. Pindar, in his first Pythian ode, says : " The sea-girt heights above Cuma, and Sicily too, press upon his shaggy breast ; and the pillar of heaven, snowy Etna, the perennial nurse of sharp pinching snow, holds him fast. From the recesses of Etna are vomited forth the purest streams of fire, immeasurable in extent. By day the fiery HIGH LANDS OF THE EARTH. 213 current pours forth a burning torrent of smoke, but by night, the red flame, rolling along masses of rock, plunges them with loud crash into the surface of the sea. That monster Mount Etna from Syracuse. sends up such horrid streams of Hephaestus (Vulcan) — a sight wonderful to look on ; wonderful, too, to hear of from those who have seen it." Etna, when viewed from a distance, appears a very symmetrical cone, but there are upwards of eighty minor yet conspicuous cones upon its sides. At a late eruption, which occurred in November 1832, the moun tain sent forth a stream of lava eighteen miles long including its windings, a mile broad, and thirty feet thick, which approached within two miles of the town of Bronte, and threatened it with destruction. In addition to this general outline of extensive volcanic regions, there are isolated spots where similar phenomena are displayed. The Peak of Teneriffe, in the Canary Islands, is an imposing volcano, with its highest crater apparently sealed up, but lateral eruptions are of recent date. Iceland, Jan May en, and the south coast of Greenland, constitute a considerable volcanic system. Fatal to human life as the eruptions of the volcano have occasionally been, large views of such physical events will awaken impressions at variance with those which their detached observation often excite. He who, living on the slopes of Vesuvius, witnesses his vine-clad dwelling, or his native village, overwhelmed with the lava and ashes of the mountain, is apt to become exclusively occupied with the disaster, and will not readily reflect upon the many millions of mankind who enjoy a quiet habitation, and whose locality has never been disturbed within the period that history and tradition have chronicled such occurrences. Yet nothing is more true than that the same agency which is occasionally destructive in a few spots upon the world's expanse, has operated in forming or upheaving the universal crust of the globe, and has thus been the means of building up sure resting places for unnumbered myriads of the human family. It is that protruding or elevating power also that has rendered the coal formations and mineral veins 2H PHYSICAL GEOGRAPHY. accessible, and thus supplied commerce with its sinews ; and comparing the physical history of the globe with the career of its inhabitants, how harmless the Etnas and Cotopaxis of nature appear, in contrast with the Caesars and Napoleons of mankind! A slight survey of the features of the external world is sufficient to show, that the tendency of their general arrangement is to minister to the happiness of man, to give him pleasure in the act of contemplation, as well as to contribute to his convenience. Its surface, so finely diversified, is eminently calculated for the gratification of its occupiers, and expands around them in every clime an array of beauty and grandeur, sometimes apart from each other, but often blended in wild yet tasteful and imposing combinations. "Wherever the traveller pene trates, he finds the terrestrial configuration so arranged in ever-varying outline as to spread before him an inviting picture of natural scenery, which captivates, or soothes, or elevates, or excites the mind, and furnishes such pleasurable emotions as dull uniformity would not have yielded. Especially do the elevations which mark the face of the earth. whether rising to the stately proportion of mountains, or forming only the rounded, green- clad hill, give interest, grace, or sublimity to the landscape. But the mountains perform a more important office than that of giving imposing effect and picturesque beauty to the scenery of the earth. Occupying a portion of its surface nearly equal to that which the sandy desert claims, they stand associated with political and other results of the highest importance to mankind. "Where the ocean does not extend its waters to divide the families, kindreds, and tongues of the human race, the granite snow-crowned rampart is frequently the line of demarcation. Nations have thus been kept apart from each other by natural boundaries; and. the difficulties connected with aggressive wars between communities thus separated, have contributed to promote peace and maintain independence. The mountains also officiate in arresting and condensing the vapours by their cold summits, and storing up their precipitated waters in interior reservoirs, from whence they issue by a thousand springs ; and in the dens and caves that perforate their declivities liberty and religion have often found a secure asylum, when assailed by persecuting power and grasping ambition. " The precious things of the lasting hills " — the phrase of the dying Hebrew patriarch — is not without its appropriate significancy. Inglis, wan dering in the Tyrol, recognised its truth, when, as he remarks, he emerged from the mountains after a day's ramble, with pleasant recollections of lights and shadows yet lingering on the vision — of solitude and stillness, and the small mountain sounds that are more akin to silence than noise — and of all the thousand deep-felt but inexpressible emotions, that are born among the eternal hills, when evening fills their valleys, creeps over their declivities, and throws its mantle on their summits. While mountains, whether volcanic or otherwise, occasionaDy rise on one side from a low level, and descend abruptly to it again on the other, they are far more generally con nected with extensive tracts of elevated country, which is either intersected or bounded by them. These highly raised regions may undulate with hill and vale, but have compara tively level surfaces, and are known as plateaus or table-lands. The principal example in Europe is in Spain, which consists of a high central nucleus, surrounded by a narrow belt of maritime lowlands. Madrid, the capital, on a plain, is 2170 feet above the sea. But the royal palace of the Escurial has an elevation of 3520 feet, very little lower than the top of Snowdon ; and the site of La Granja, the summer residence of the sovereigns, is elevated 3943 feet. This would appear a castle in the air, if isolated, and viewed from the sea-level, being at a greater altitude than the summit of Vesuvius. The grand examples of plateau formations are Trans- Atlantic and Asiatic. A considerable portion of Bolivia and Upper Peru, is a plateau remarkable for its altitude, 13,000 feet. It is formed by the top of the main mass of the Andes, and stretches between the mountain-knots of Cuzco and Potosi, north and south, and the Cordillera HIGH LANDS OF THE EARTH. 215 Real, and the Cordillera of the coast, east and west. The included area, far exceeding that of Great Britain, has a surface varied with hills and valleys, streams and lakes. Upon it lie the waters of lake Titicaca, twenty times larger than the lake of Geneva, with the decayed mining cities of Cuzco and PotosL Potosi, 13,350 ft.,. Cerro dc Potosi Bolivian Plateau. Less elevated and extensive, but grandly situated, is the table-land of Quito, a plain, two hundred miles long, by thirty broad, at the height of 9500 feet, engirdled by magnificent projections of the Andes. "From the terrace of the government palace," says Humboldt, speaking of the city of Quito, " there is one of the most magnificent prospects that human eye ever witnessed, or nature ever exhibited. Looking to the south, and glancing along towards the north, eleven mountains covered with perpetual snow present themselves, their bases apparently resting on the verdant hills that surround the city, and their heads piercing the blue arch of heaven, while the clouds hover midway down them, or seem to crouch at their feet." In the same region, the upland plain of Santa Fe de Bogota, is an almost perfect level, 8600 feet high, and forty-five miles, by twenty in extent, environed with high mountains, through which the waters of the plain escape by a narrow outlet, and form the celebrated falls of Torquedama. In North America, nearly the whole of Mexico consists of high table-lands, mutually connected, at the mean height of 7000 feet. They are interspersed with numerous streams and lakes ; and form a platform for the colossal cones of Colima, Popocatepetl, Orizaba, and Nevada de Toluca, crowned with eternal snow. Colima, 12,000 ft. zaba, 17,374 ft. t of Snow, 14,800ft. Pacific Ocean. Gulfof Meiico. Mexican Plateau. In consequence of this configuration of the country, while the heat common to tropical lands is experienced on the low shores, the climate becomes temperate as the traveller ascends the interior highlands, and it is cold and frigid at the altitudes attained by the mountains. The loftiest and most extensive plateau region on the face of the globe is the vast protuberance of Central or High Asia, which comprises different systems of table-lands. Between the Himalaya and the Kouenlun chains, lie the Thibets, a district of various but great elevation, called the plateau of Great Tatary. At a house of the Dalai-lama, near the margin of the two lakes, Manasa and Kawana-hrada, Captain Webb makes the height 14,502 feet, thus far exceeding that of the waters of Lake Titicaca. To behold the lake Manasa, an oval basin, fifteen miles by eleven in extent, is deemed by the Hindoos a felicity beyond every other on earth, but prodigious difficulties attend the pilgrimage. 216 PHYSICAL GEOGRAPHY. High Asia is walled in on the western side by the Bolar chain or Cloudy Mountains, in connection with which there is still loftier table-land. This is the remarkable region of , Mount Everest, »,000 ft. / Kncn'.un. '1'Uuiu Chan. iduch?, Altai Nts . ll.oa ft. Plateau of Central Asia. Pamir, locally called Bam-i-duniah, or the " Eoof of the World," a plain at the height of . 15,600 feet, but a trifle lower than Mount Blanc. The Oxus has here its source ; and it forms the water-parting between its basin and that of the Indus, with other rivers, which run off to different seas. The locality is a remarkable one, dreary in its aspect, and hard to climb, owing to the encumbering snow and steep declivities, while it is also difficult for the stranger to reach, on account of the rarefaction of the atmosphere. Still it is occupied by various forms of animal and vegetable life, and is annually for a time the residence of a native wandering people. The snow lies deep upon the "Eoof" for the greater part of the year, but disappears in summer, though masses remain unmelted in hollows and shaded places. During this season, the spot is a favourite resort of the Kirghis, for the pastming of their cattle, who retire into the sheltered valleys at lower levels as the winter approaches. It is also traversed by merchants as the commercial route between Bokhara and the Chinese empire. A fine sheet of water lies upon the table-land. This is the Sir-i-kol, the loftiest lake of the globe. Marco Polo, the Venetian traveller, in the last half of the thirteenth century, passed through this region on his remarkable Oriental journey, and has left on record accurate notices. He particularly observed, without understanding the cause, that fire did not burn with the same vivacity and strength as in other places, neither did it cook victuals so well. He was the first to point out this circumstance, which has been verified by others at high elevations, and is doubtless the effect of the rarefaction of the air. For five centuries and a half afterwards, we have no record of any European having reached the spot, till Lieutenant Wood, after surmounting innumerable difficulties and dangers, stood, to use the native expression, upon the " Roof of the World," and beheld the expanse of lake Sir-i-kol stretched out before him, covered with thick ice, with the infant and classical river Oxus issuing from it. This was on the 19th of February 1838, at five o'clock in the afternoon. He ascended by the valley of the river from Bokhara, accom panied by a party of natives. On approaching its source, the snow lay deeper and deeper every step in advance, for the winter season added immensely to the difficulty of the undertaking. Two hours were occupied in forcing a passage over a field of snow not five hundred yards in extent. On attempting to proceed more rapidly over a favourable site, a guide seized the bridle of his horse, and cautioned him against the "wind of the mountain," alluding to the highly rarefied air, which speedily arrests exertion. Wishing to ascertain the depth of the lake, he tried to make an opening in the ice, but found the slightest muscular effort too exhausting to proceed. Half a dozen strokes of the axe prostrated the workman ; and though a few minutes' respite sufficed to restore the breath, anything like continual labour was impossible. A short run mado the runner gasp ; the pulse throbbed at a fearful rate ; the voice was sensibly affected ; and conversation in a loud tone was too painful to be maintained. VALLEYS AND GBEAT LEVELS OP THE EARTH. 217 CHAPTER III. VALLEYS AXD GREAT LEVELS OF THE EATITH. T lias been observed, that the ridge line of a chain of mountains is marked with great irregularities, numerpus breaks and de pressions occurring. Though the base of these depressions is at a high elevation above the general superficies, yet when in ternally surveyed they have all the appear ance of being sunk far below it. The traveller slowly wending his way through them, shut out from any extensive observa tion of the country, and seeing on each hand eminences towering far aloft, might imagine himself at an immense depth be neath the surface land of the globe. They are mountain chasms, through which com munication is maintained between opposite sides of the ridge they intersect, and are called Cols in the Alps, Ports in the Pyrenees, Gaps in the United States, and in general, gates, or passes. They abound with scenes of striking grandeur — overhanging rocks, xindefended precipices, patches of wood, and cascades of water, rendered the more impressive by the seclusion of their sites. Some of the present passes across the Alps have been frequented from a very early period, but many natural obstacles have in modern times been removed by the art and labour of man, and the difficult mule paths of a former age been converted into carriage roads. The Carthaginians are supposed to have entered Italy under Hannibal by the pass of the Great St. Bernard ; at least the weight of evidence is in favour of this route, which was made practicable for cars by order of Augustus, and along this course Pepin certainly led his army to attack the Lombards. "It is natural," says Mr. Inglis, "to compare one mountain pass with another ; and after having for the first time crossed any celebrated mountain, one naturally calls to mind the journeys which one may have made across other mountains, and the comparative interest with which such journeys have been attended. I need scarcely say, that there are certain features common to all mountain passes ; that there is sublimity in elevation ; that mountain clefts are filled by rivulets, which swell as they descend ; that plants of less or more interest attract the eye ; that from certain heights, extensive prospects of the country below are laid open ; and that the phenomena of clouds, rain, and rainbows, and the effects of lights and shadows are common to all great elevations. But notwithstanding these features of common resemblance, mountains and their passes widely differ in interest, and consequently in the features by which nature has distinguished them. These differences, supposing the mountains to be equal in height, arise from the diversity in conformation, and the variety in their geological character. When we talk of one mountain pass being finer than another, we mean that the views it affords are more 218 PHYSICAL GEOGRAPHY. sublime, or more picturesque ; that sublimity, and that picturesqueness, are the result of their shape and surface. I have never passed either Mount Cenis, or the Simplon ; J cannot therefore speak of them. The passes with which I am acquainted are, St. Go- thard; Mount Albula ; the pass by the sources of the Rhine ; the Ehetian Alps ; the Brenner ; the limb of the Pic du Midi ; the pass of the Pyrenees from Perpignan to Cata lonia, and from Gavarnie by the Breche de Roland to Arragon ; some of the mountain passes of Norway ; and the Spanish Sierras. Now it may seem singular, that of these, the lowest passes should be the finest ; yet so it is in my esti mation. Mount Albula, and the Breche de Roland, are certainly lower than St. Gothard, and yet their features are more striking ; and the truth is, that besides the causes I have already mentioned, arising from diversity in conformation and surface, the very lowness is itself the chief cause of superiority. Nor is that apparent paradox difficult to explain. Where a road traverses the summit of a mountain, there cannot be precipices above ; and the mere fact, that a road is necessarily led over the highest part of a mountain, is itself a proof that it is not indented by those deep valleys, clefts, and ravines, which, did they exist, would permit the road to be conducted across at a lower elevation. Where a road traverses the summit of a mountain the views may be extensive ; but they must yield in sublimity to those which are presented where the road conducts the traveller through the heart of the mountain, — among its deep recesses, its forests, and cataracts." The ancients esteemed the passes of the mountains bounding their respective terri tories, or intersecting them, of great military importance, and added to their natural strength to render them impregnable. Pliny thus describes the defiles of the Caucasus, and the mode of maintaining them : — " Each pass was closed by large beams of wood pointed with iron. In the midst of the narrow valley flowed a river. The southern extremity was protected by a castle built on a high rock. This defence was to prevent incursions from the people of the north." Three great passes through the Caucasus are spoken of by the classical writers, the Pyle Sarmatae, the Pyle Albania, and the Via Caspia. The former, probably the Porta Caucasia of Strabo, is the particular one VALLEYS AND GREAT LEVELS OF TUE EARTII. 219 referred to by Pliny, now the pass or valley of the river Terek, one of the ancient keys of the East. The river has its rise towards the centre, and flows northward, a foaming torrent, by the side of which the emperor Alexander caused the present road out of Europe into Georgia to be constructed in the year 1804. The road winds by the edge of precipices rising up from the roaring waters of the Terek, while above, large projections of rock, many thousand tons in weight, hang from the beetling steep of the mountains, threatening destruction on all below — not always a vain apprehension. After the winter season, many of these huge masses have been launched downwards by the effect of a sudden thaw, blocking up the narrow pathway, or flooding it by the obstruction offered to the course of the river. The mountain sides of this pass — from one of which the lofty Ivasibeck rises four thousand feet above the limit of perpetual snow — are so high, close, and overhanging, that even at mid-day the whole is covered with a shadow bordering on twilight. At Darial, about a day's journey up the European side of the pass, the Russians have a military post. The scene is here one of great magnificence. The walls of rock reach the height of nearly four thousand feet above the bed of the river. The passes of the Taurus, which are the channels of communication between the interior plains of Asia Minor and the southern coast, have milder features. The most celebrated in antiquity — the Pyla3 Ciliciae — through which the younger Cyru>3 and Alexander poured their armies, consists of a narrow defile, with cliffs covered a considerable way up with evergreens and pine-trees, hanging in some places like a vast canopy over the road, while bare and desolate peaks tower above the clouds. The passes of the Andes and Himalaya exhibit Nature in her wildest and most terrific aspects, and are perilous sites. The latter especially, owing to their elevation in the regions of eternal ice and snow, are seldom traversed without the loss of human life, and yet are annually travelled by crowds of people journeying to and from the Indian and Tartarian sides, on purposes of traffic, rarely proceeding a mile, at the higher points, without meeting with the remains of some ill-fated wayfarer. Captain A. Gerard accomplished the ascent of the Mannering Pass, 3000 feet higher than Mont Blanc, and thus describes the scene and its dangers : — " The river Darboong was lost among the fields of snow and ice by which it was generated ; the whole space on every side was floored by ice, half hid under stones and rubbish. In some places the snow is of an incredible thickness, and lies in heaps. Having accumulated for years together, it separates by its gravity, and spreads wide desolation in its route. Nowhere, in all my travels, have I observed such enormous bodies of snow and ice, or altogether such a scene. So rapid and incessant is the progress of destruction here, that piles of stone are erected to guide the traveller, since the path way is often obliterated in a few days by fresh showers of splinters. Our elevation was now upwards of 16,000 feet, although we had but ascended in company with the river. Here only began our toils : we scaled the slope of the mountain very slowly ; respiration was laborious, and we felt exhausted at every step. The crest of the pass was not visible, and we saw no limit to our exertions. The road inclined to an angle of 30°. Vast benches of limestone, like marble, were passed under ; the projections frowned over us in new and horrid shapes ! Our situation was different from any thing we had yet experienced : it cannot be described. Long before we got up, our respiration became hurried and oppressive, and compelled us to sit down every few yards ; and then only could we inhale a sufficient supply of air. The least motion was accompanied by debility and mental dejection : and thus we laboured on for two miles. The last half-mile was over the perpetual snow, sinking with the foot from three to twelve inches, the fresh covering of the former night. The direct road leads to the centre of the gap, where the snow is very deep and treacherous ; and we made a circuit to the right, to avoid the 220 PHYSICAL GEOGRAPHY. danger of being swallowed up in one of the dark rents into which often shepherds and their flocks have sunk, never to rise. The day was cloudy, and a strong wind half froze us. The rocks were falling on all sides, and we narrowly escaped destruction. I myself twice saw large blocks of rock pass with dreadful velocity through the line of people, and between two of them not four feet apart. At half-past two I reached the summit." The broad and deep depressions in mountainous districts — properly speaking, valleys — are ranged into two classes, according to their direction in relation to the main eleva tions. Those which are situated between two principal ridges are termed longitudinal, and those which are at right angles with a great chain, or variously inclined, are called transverse. Valleys also are styled lateral which feed, with tributary streams, a great watercourse ; and by the terms upper and lower valley, parts of the same valley, near and more remote from the source of a river flowing through it, are denoted. The. canton of the Valais in Switzerland — one of the most remarkable spots upon the globe, combin ing, within a very contracted area, the productions and temperature of every latitude from the arctic to the torrid zone — is a longitudinal valley, the largest in the Swiss Alps. Its axis is parallel to the main chain of Mont Blanc and Mont Rosa on the south, and the ridge of the Bernese Alps, with the grand heights of the Jungfrau and Finster-Aar-Horn, on the north. The Rhone passes through it, rising at its western extremity among the glaciers of Mont Furca, at the height of 5726 feet above the sea, descending to an elevation of 1350 feet before it escapes out of the valley towards the Lake of Geneva. The valley is nearly a hundred miles long, the breadth of the base varying from a quarter of a mile to three miles. It can only be entered on level ground at one point, where the Rhone rushes out of it through a narrow gorge formed by the Dent de Midi and the Glacier of the lihone. Dent de Morcles, which rise 8000 feet above its waters. Connected with this great longitudinal valley, there are thirteen lateral valleys on the south side, and three on the north, which bring down the waters of its enclosing mountains. The canton of the Grisons also comprises upwards of sixty transverse valleys, belonging chiefly to those which are longitudinal — those of the upper and lower Rhine, and the Inn. These bye-valleys are often nooks into which man seldom pries, and where no specimens of his handiwork are to be found. There are no sights or sounds but those of Nature, exhibiting herself in rock, wood, heath, and mossy flower, and speaking by the rippling rivulet, as if inviting the enquiry — VALLEYS AND GREAT LEVELS OF TilE EARTH. " Free rover of the hills, pray tell me now The chances of thy journey, since first thou From thy deep-prison'd well away didst break, A solitary pilgrimage to take. Among the quiet valleys, I do ween Thou with the daisied tufts offender greou Hast loving linger'd ; didst thou not awake, With thy soft kiss, the hare-hell bending low, Stealing her nectar from the wild bee's wooing ? And thou hast toy'd (though thou wilt tell me, no !) With many a modest violet, that looks Into thy grassy pools in secret nooks. Come, tell me, rover, all thou hast been doing ! " The larger Pyrenean valleys differ from the Alpine in being transverse, running at various angles with the principal range. There are those which are longitudinal, but not of equal extent with the former. It is common also for a Pyrenean valley to present the form of a succession of basins, at various distances from each other, called " oules," meaning pots or boilers, in the language of the mountaineers. These basins are large circular spaces covered with alluvial soil, sometimes eight miles in length by four in breadth, through which the streams flow sluggishly, owing to their level surfaces. They have all the appearance of having once been lakes, the beds of which have been emptied, by the waters bursting through their mountain ramparts. In fact, in the upper parts of these valleys, the basins exhibit lakes at present, some of which are on very elevated sites. Make Brun enumerates eight which are at the height of 6557 feet ; but that of the Pic-du-Midi is 8813, and is perpetually covered with ice. In the regions of the Andes, the longitudinal and transverse valleys constitute the most majestic and varied scenes which the Cordilleras present, and produce, says Humboldt, the most striking effects upon the imagination of the European traveller. The enormous height of the mountains cannot be seen as a whole except at a considerable distance, when in the plains which extend from the coast to the foot of the central chain. The table-lands which surround the summits covered with perpetual snow are, for the most part, elevated from 8000 to 10,000 feet above the level of the ocean. That circumstance diminishes to a certain degree the impression of grandeur produced by the colossal masses of Clumbora90, Cotopaxi, and Antisana, when seen from the table-land of Quito. Deeper and narrower than those of the Alps and Pyrenees, the valleys of the Cordilleras present situations so wild as to fill the mind with fear and admiration. They are formed by vast rents, clothed with a vigorous vegetation ; and of such a depth that Vesuvius might be placed in them without overtopping the nearest heights. Thus, the sides of the celebrated valleys of Chota and Cutaco are 4875 and 4225 feet in perpendicular height ; their breadth does not exceed 2600 feet. The deepest valley in Europe is that of Ordesa in the Pyrenees, a part of Mont Perdu ; but this, according to Ramond, is not more than 3200 feet deep. The valley form in more open regions is that of a depression, generally a water-course, with rounded and gently swelling embankments. The largest specimens of this class in Europe are found along the coast of the Danube, and the other great rivers, which frequently open out into extensive plains, and are the grand seats of population. Of a similar character are the vales of York, Aylesbury, and Exeter, in our own island. Some of the spots, too, which pass in our own country under the humble name of dales, are true pictures, though in a miniature form, of the high-walled valleys of Alpine and Andean districts. Perhaps the best representation, and certainly one of the most exquisite specimens of scenery we have, is the Dovedale of the Peak, so styled from its locality being in the Peak of Derby- 223 PHYSICAL GEOGRAPHY. shire, and from the name of the stream, the Dove, that flows through it. This is a valley between high and precipitous limestone rocks, three miles in extent, the sides closely approximating in some places, and again expanding. It seems as if it had been formed at once by some convulsion of nature, which rent asunder what had before been a vast compact mass, an impression often made by the appearance of valleys in mountain regions. Sometimes their opposite sides present salient and re-entering points, which so exactly correspond, that if it were possible to bring them to gether, it seems as though they would fit into each other, leaving little trace of their former separation. Dovedale is approached on the west through a confined defile remarkable for its deep seclusion, of which Dr. Plot states, that the side-walls are so high that in rainy weather their tops may be seen above the clouds, and they are so close, that the inhabitants, a few cottagers, in that time of the year when the sun is nearest the tropic of Capricorn, never see it ; and when it does begin to appear, they do not see it till about one o'clock, which they call Narrowdale noon, using it as a proverb when anything is delayed. " Valley of Shadow ! thee the evening moon Hath never visited ; the vernal sun Arrives too late to mark the hour of noon In thy deep solitude : yet hast thou One Will not forsake thee : here the Dove doth run Mile after mile thy dreary steeps between." In Dovedale itself, the high eminences that form the lateral walls of the valley — the projecting rocks assuming the most fantastic shapes — sharp pinnacles and bold bluffs — the stream that flows at their base, now still, now murmuring, and dashing over a barrier of stones that have fallen from the heights into its bed — the wild flowers common to the limestone stratum — the copses of mountain ash — all combine to form a scene that satisfies at first sight, and increases in interest the more it is examined. This is an example, therefore, of valleys of dislocation, so called from having apparently been formed by the breakage of the general mass in the process of upheaval. Sometimes there has been upheaval without fracture, but with more effect at particular points, causing intervening depressions, which are termed valleys of undulation, of which an example is given at page 630, from the Jura mountains. Valleys of denudation are those which appear to have been formed by the action of water upon soft and practicable strata ; but VALLEYS AND GREAT LEVELS OF THE EARTH. 223 there can be little doubt that most valleys, from the grand rents of mountain ranges to the wide and gently sweeping hollows of the general surface, are mainly due to internal causes of disturbance, their physiognomy being subsequently modified by aqueous and atmospheric agency. The great depression of Western Asia, embracing many thousands of square leagues, of which the Caspian Sea and the Sea of Aral are the lowest points, is supposed to be intimately connected with the upheaval of the Caucasus, the plateau of Persia, and of High Asia. When the valley form of the earth occurs upon a grand scale, there are points at which the traveller loses sight completely of the high lands that environ it. He beholds, stretching out on every side, a tract of level land, or at least the diversity of hill and vale occurs in such an unimportant degree as not essentially to disturb the idea of being in a flat country. The forces which have given such a peculiar character of variety to mountainous districts have only affected, to a comparatively feeble extent, these portions of the terrestrial superficies. In the former, the difference between high and low is often that of thousands of feet in a very small space, while in the latter frequently it does not amount to fifty feet, nor in some cases to ten, through a wide area. The surface rises and falls in gentle wavy undulations, here and there interrupted with bolder features, while occasionally a dead level is exhibited. These tracts may be collectively called plains, using the term in its geographical sense, not as meaning a perfectly horizontal surface, but an extent of generally level country. They are known in the Old World under a variety of names, as heaths, landes, steppes, tundras, and deserts. Europe contains an immense extent of low flat land. It comprises part of northern France, the greater part of Belgium and northern Germany, all Holland and Denmark, the Avhole of Poland and southern Russia, thus stretching from the banks of the Seine to the terraces of the Ural and the waters of the Black Sea. This region, in general very level and fertile, traversed by numerous navigable rivers, is the birth-place and surface land of a large amount of modern civilisation. It is a vast plain with two grand declivities, inclining north and south-easterly, which determine the course of the superficial waters either to the Baltic Sea and the German Ocean, or to the basin of the Black Sea. As an instance however of the little inclination of the surface in some places, a prevailing north wind will drive the waters of the Stattiner-Haf into the mouth of the Oder, and give the stream a backward flow for an extent of thirty or forty miles. At the northern confine of the European lowlands, to a considerable distance from the shore, there is only a very slight elevation above the sea, and hence extensive marshes are formed along the coast. Holland is to a great extent so near the level of the waters as to require artificial means to protect it from inundation ; and on approaching it, the trees and spires seem as if planted upon the ocean. Notwithstanding the general fertility of this tract of country, we meet with many spots incapable of cultivation, either wholly bare of vegetation, or only producing a few grasses and dicotyledonous plants, which constitute true heaths and landes. The moor and bog-lands of Westphalia are remarkable for their flat and table- formed surfaces. From the middle of the Beerktanger Bog, heaven and earth seem to mingle ; no tree, no bush is to be seen far as the eye can reach ; while here and there the play of refraction magnifies to elephants the small and coarse- woolled sheep which find a scanty subsistence on the Erica vulgaris, which vegetates on the scattered productive portions of the bog. The infertile plains, for the most part sandy, occur chiefly in north Germany and Prussia, those of Liineburg and its vicinity occupying a space of about six thousand square miles. Similar sandy plains, interspersed with heaths and marshes, occupy an extensive space in the south of France between the Gironde and the Pyrenees. Towards its eastern extremity, the great level of Europe abounds with enormous tracts of pasture land, which appear to have been rendered smooth by a long abode of the waters 224 PHYSICAL GEOGRAPHY. upon their surface. On these pastures nothing interrupts the view. The eye only finds a restin"1 point at the horizon, and the traveller may pass over them for miles without Great Plain of the Caucasus. meeting with a village or a single house. From the mouths of the Danube, along the coasts of the Black Sea to the Don, these green plains terminate at the horizon with an azure line, such as is commonly perceived in the open sea. They possess the finest soil, a black rich mould, which with slight cultivation produces in great abundance all the cerealia, and even hemp and poppies. Nature, here left to herself, affords the most luxuriant and succulent pastures, in which herds of splendid oxen, such as are found in Holstein and Holland, graze night and day. From time to time, a few huts are met with, indicated on the charts as inns or post-houses. The transition from cultivation to nomadic life, is recognised in this region, which is more palpable as an easterly direction is pursued, and gradually the aspect of the country changes, becomes wavy, undulating, and less fertile. Everything here, says Humboldt, speaking of the district east of the Don, awakes the anticipation of the steppes of Asia — the climate itself, with its hot summer, its cutting and sharp winter, and dry east wind, and even man himself ! The region of the steppes commences in Europe, and occupies almost the whole of the north-west of Asia. They are extensive and almost treeless plains, intersected with barren ridges and hills, with vegetation of rank coarse grass in the intervening spaces ; at least this is their general character on the European side of the Volga. Mr. Stephens, the American traveller, thus describes his first acquaintance with them : — "At daylight we awoke, and found ourselves upon the wild steppes of Russia, forming a part of the immense plain which, beginning in northern Germany, extends for hundreds of miles, having its surface occasionally diversified by ancient tumuli, and terminates at the long chain of the Urals, which, rising like a wall, separates them from the equally vast plains of Siberia. The whole of this immense plain was covered with a luxuriant pasture, but bare of trees, like our own prairie lands, mostly uncultivated, yet everywhere capable of producing the same wheat which now draws to the Black Sea the vessels of Turkey, Egypt, and Italy, making Russia the granary of the Levant ; and which, within the last year, we have seen brought six thousand miles to our own doors. Our road over these steppes was in its natural state, that is to say, a mere track worn by caravans of waggons ; there VALLEYS AXD GREAT LEVELS OF THE EARTH. 225 were no fences, and sometimes the route was marked at intervals by heaps of stones, intended as guides when the ground should be covered with snow. I had some anxiety about our carriage ; the breaking of a wheel would have left us perfectly helpless in a desolate country, perhaps more than a hundred miles from any place where we could get it repaired. Indeed, on the whole road to Chioff there was not a single place where we could have had any material injury repaired ; and the remark of the old traveller is yet emphatically true, that * there be small succour in these parts.' " Nothing is more remarkable than the successive appearance of thousands of tumuli, which overspread the great levels of southern Russia. They are mounds of earth — the mansions of the dead of past ages — occupying sites which are now tenantless for leagues around them, and only visited occasionally by droves of cattle and the passing traveller. Observing only a few specimens, they might be concluded to be indications of the route between different places, did not their number, symmetrical form, general resemblance, and contents, when ever opened, disprove the idea. The earliest adventurers from the west of Europe into these waste places mention the tumuli. " We journeyed," says William de Rubruquis, " with no other objects in view than earth and sky, and occasionally the sea upon our right, which is called the sea of Tanais ; and moreover the sepulchres of the Comani, which seemed about two leagues distant, constructed according to the mode of burial which characterised their ancestors." Simple as these funereal monuments are of an ancient world, their very simplicity is sublime, harmonising with the appearances of nature in the steppes, unaffected by the hand of Time, by which the Parian marble is speedily defaced. Among the occurrences of the steppes, that of a grass fire is not uncommon, occasioned by the unextinguished embers left by parties who have bivouacked in them, which lay hold of the high and dry vegetation in their neighbourhood, and spread temporary desolation over large tracts of country. The monotony of these plains gives great effect to the appearance of the Caucasus. On the approach from the north, these mountains are seen at a vast distance, rising abruptly from a level country, apparently an impassable barrier stretching from the Caspian to the Black Sea, the white head of Elburz towering above the lower summits of the range. In the diagram is represented Mount Kasibeck, the snowy region beginning at fig. 2., a height of 10,200 feet; opposite/^. 3. is the bed of the Terek ; fig. 4. shows the profile of hill near the Steppe ; 5. the level of the Caspian, and 6. of the Black Sea. On the eastern side of the Volga, the steppes extend far into the heart of Asia ; but their physiognomy greatly alters. The soil becomes more unfruitful ; vegetation only shows itself here and there ; the salt steppes appear, abounding in pools and streams of salt and bitter waters, on the banks of which the willow and the reed only grow — the sole means of supporting the herds of the Turcoman in winter, whom circumstances therefore render nomadic. The desert plains — meaning not merely solitudes, but sandy and stony wastes — occupy an enormous space of the lowland regions of the globe. They are rare on the continent of America, but occur in the lower part of Peru, where a considerable district is found, exhibiting the features of a true Sahara — a surface of rock covered with moveable sand, not a drop of rain falling upon it. Still such tracts are seldom met with in the New World, while they are so abundant upon the ancient continent as to constitute a marked distinction between the two regions. The reproach is of old standing against Africa, of being the most barren and unproductive of the great divisions of the earth — a reproach Steppes of the Caucasus. 226 PHYSICAL GEOGRAPHY. which especially applies to an immense domain extending on both sides of the tropic of Cancer, but having its main direction from west to east, and including more than a fifth part of the whole of that territory. This is the Sahara-bela-ma of the Arabs, or desert without water, called also the Bahar-bela-ma, or ocean without water. Upon a large space of this district there is neither rain nor dew, to awaken in the glowing bosom of the earth the germs of vegetable life. From the west coast of Africa, and between Morocco- on the north and the Senegal river on the south, this wilderness extends easterly to the Red Sea, contracted towards the west by a projecting part of the kingdom of Fezzan, and interrupted on the east by the narrow valley of the Nile. It embraces a space of more than 46° of longitude and 15° of latitude, or a length of 3000 miles by a breadth of 1000. A large extent of the Sahara is a dead level ; but low sand hills, wadys or valleys, and projecting rocks are frequent. " Now the naked rock" says Humboldt, describing its characteristics, "appears to view perfectly smooth and level, which the traveller may pass over for days together without meeting even a grain of sand, where one sees only the heaven above and the hard stone pavement beneath ; now we behold a flat plain covered with rolled pebbles, here and there intersected with ravines and valleys extending to about thirty feet below the surface ; and now an ocean of sand presents itself, frequently containing so large a quantity of salt, that whole tracts appear coated with it, and resemble fields of ice. Occasionally spots of verdure are found, known under the name of oases, which display palm trees and springs of water." The Egyptians, says Strabo, give the name of oases to inhabited spots surrounded by vast deserts of sand, and resembling islands in the sea. There are, he states, many such in Lybia, while three border on Egypt, and are referred to that country. Modern discovery has, however, made us acquainted with several of these isles of the African ocean of sand, which are rich in streams and vegetation. In the western part of Fezzan, in a hollow surrounded by ^^=^^* ~-^P 4?^"- .- -' -ILjV" Lake of Mandia. rocks, lies the small lake of Mandia, celebrated for the occurrence of Trona, or pure natron (soda). Oudney and Clapperton, on their memorable expedition from Tripoli, visited this lake. Clapperton, as Oudney tells us, was sitting on the top of a high sand hill, and so pleased with the view, that he called out several times to his companion to dismount from his camel to enjoy the treat. The appearance was beautiful. There was a deep sandy valley, containing only two lai'ge groves of date trees, enclosing a fine lake. The contrast between the bare lofty sand hills, and the two insulated spots, was the great cause of the sensation of beauty. There is something pleasing in a lake surrounded with vegetation ; but when every other object within the sphere of vision is dreary, the scene will become doubly so. No doubt the oases in general owe much of their reputation to the contrast they form with the absolute barrenness of the desert. With the exception of these spots, the Sahara is uninhabitable for man ; and it is only at periodic times that it is traversed by the trading caravans, which proceed across it from Tafilet to Timbuctoo, and from Fezzan to Bornou. These are bold undertakings, the practicability of which depends upon the life of the camel — the ship of the desert, as the animal is VALLEYS AND GREAT LEVELS OF THE EARTH. 227 termed in the poetical language of the Orientals. One chief source of danger arises from the Simoom, a hot southerly wind, which rolls along in suffocating masses the sandy billows, darkening the air, and frequently overwhelming every object in their path. Sand Storm in the Desert. This wind in passing over the desert acquires an extraordinary degree of heat and dryness, and stops respiration at once upon exposure to it. To avoid its effects, the Arabs drop the Kafieh, a handkerchief which they wear upon their heads, so as to cover their faces. If the immediate perils of this fierce burning blast are escaped, it often happens that the water contained in the skins borne by the camels is absorbed ; and in such circumstances, if at too great distance to obtain a fresh strpply in time, the whole company fall victims to intolerable thirst. In this way an akkabah or caravan, consisting of 2000 persons and 1800 camels, was cut off in the year 1805. The Sahara is one principal theatre of that singular optical illusion called the " mirage," to which the Arabs apply the more poetical name of the Lake of the Gazelles. This is the appearance of tmcts of water in the desert — a deception supposed to ai'ise from the reflection which takes place between strata of air of different densities, owing to the radiation of heat from the plains of sand. These mock lakes — the "waters that fail," or that have no reality — often torment the passenger oppressed with heat and thirst. Major Skinner describes a deception of this kind, the most perfect that could be conceived, which for a time exhilarated the spirits of the party with whom he jour neyed in the desert, and promised an early resting-place. They had observed a slight mirage two or three times before ; but the one in question surpassed all that could well be fancied. Although aware that these appearances have often led people astray, he could not bring himself to believe that this was unreal. Even the Arabs were doubtful. The seeming lake was broken in several parts by little islands of sand, which gave strength to the delu sion. The dromedaries of the sheikhs at length reached its borders, and appeared to have commenced to ford, as they advanced and became more surrounded by the vapour. They seemed to have got into deep water, and to be moving with greater caution. In passing over the sand-banks, their figures were reflected in the water. So convinced was one of the party of its reality, that he dismounted and walked towards the deepest part of it, which was on the right hand. He followed the deceitful lake fora long time, and appeared to be strolling on its banks, his shadow stretching to a great length beyond. There was not a breath of wind ; and the sultriness of the day would have added dread- 223 PHYSICAL GEOGRAPHY. fully to the disappointment, if the party had been much distressed for want of water. The Sahara is now well known to be advancing from east to west, besides being in a condition of internal instability, owing to the sand-storms altering the appearance of the surface. The prevailing currents of air that sweep over it are from east to west, and the flying sands travelling in that direction, there enlarge its bounds. The Wandering Sea is one of the Arab titles of a sandy desert. The Sahara apparently terminates at the valley of the. Nile, but the same identical region is prolonged beyond that channel. It embraces nearly the whole of the Arabian peninsula, which, excepting a few enclosed valleys, is a stony and barren tract, and generally an infertile level, presenting great sandy plains, producing little besides the acacia vera, or Egyptian thorn, and a few other plants. North of this is the Syrian Ituins of Palmyra from the Desert.. desert, which lies between the range of Lebanon and the Euphrates, in the heart of which is the oasis, containing the relics of one of the mysterious cities of antiquity, the Tadmor in the wilderness of a remote time, the Palmyra of a moi-e modern age. It is not difficult to conceive of the effect of its ruins after passing through a waste in many places without a single object showing either life or motion ; Corinthian columns of white marble contrasting finely in their snowy appearance with the apparently boundless yellow sands, the monuments of an opulence and art, every other trace of which has vanished with the people by whom it was enjoyed. A day in this desert is admirably described by the author of Eo'then : — "As you are journeying in the interior you have no particular point to make for as your resting-place. The endless sands yield nothing but small stunted shrubs ; even these fail after the first two or three days, and from that time you pass over broad plains — you pass over newly-reared hills — you pass through valleys that the storm of the last week has dug ; and the hills and the valleys are sand, sand, sand, and only sand, and sand, and sand again. The earth is so sandy, that your eyes turn towards heaven — towards heaven, I mean, in the sense of sky. You look to the sun, for he is your task-master, and by him you know the measure of the work that you have done, VALLEYS AND GREAT LEVELS OF THE EARTH. 229 and the measure of the work that remains for you to do ; he comes when you strike your tent in the early morning, and then, for the first hour of the clay, as you move forward on your camel, he stands at your near side, and makes you know that the whole day's toil is before you : then for a while, and for a long while, you see him no more — for you are veiled and shrouded, and dare not look upon the greatness of his glory ; but you know Avhere he strikes over head by the touch of his flaming sword. No words are spoken ; but your Arabs moan, your camels sigh, your skin glows, your shoulders ache ; and for sights you see the pattern and web of the silk that veils your eyes, and the glare of the outer light; but conquering Time marches on, and by and by the descending sun has compassed the heaven, and now softly touches your right arm, and throws your lank shadow over the sand, right along on the way to Persia." Beyond the Euphrates to the Tigris, with the exception of slips along the two rivers, the country is a desert of burning sands and sterile gypsum, thickly studded with saline and sulphurous pools ; and farther eastward the zone of deserts may be traced through Persia, Grand Tartary, and the great central plateau of Asia, extending thus in an almost continuous band of varying breadth from the Atlantic Ocean to the wall of China. Analogous phenomena to those of the Sahara — the mirage and encroaching sands — are displayed through the greater part of this zone, which proceeds in a circle, the arc of which is directed towards the south, through the whole of the ancient world. Especially in some regions of south-western Asia has the dry element sensibly advanced. Once rich and-blooming territories, celebrated by the Persian poets as paradisiacal, the theatre of heroic deeds, the seat of political power and intellectual culture, the site of cities which in size and splendour were second to none in Asia, have been visited by the moveable sand, leaving but few evidences of former grandeur and fertility apparent. At Samarcand and Bokhara, celebrated sovereign cities, from which, in the middle ages, bold and chivalrous princes overspread the East with their flying squadrons, the sands have with difficulty been kept at bay. The river Sihun has been compelled to alter its course, and the mighty Oxus of the ancients, according to historical evidence, has lost its Caspian arm in a struggle with the desert. Setting aside the fertile oases, Humboldt supposes the area of the sandy deserts, leaving out those of central Asia, to be 300,000 square leagues. Those of the Tartarian table-land cannot be less than 100,000 more, and adding 100,000 for similar tracts in Midland and Southern Africa, with some other districts, we have a grand total of half a million of square leagues of such surface in the Old World ; a space equal to the whole extent of Europe. The deserts to which the preceding notices refer, are for the most part hot sandy districts, or experience great alternations of heat and cold. Independently of these, there are cold tracts of lowland, chiefly found in the northern regions of Asia. From the declivities of the Ural on the west, to the coast of Kamtschatka on the east, and from the foot of the Altaian Mountains on the south, to the icy margin of the Arctic Ocean on the north, there is a country almost as large as Europe, a melancholy desert, in which, in latitude 67°, the growth of trees ceases altogether ; and a little higher up the soil is frozen the whole year through, some few inches of the surface alone being subject to an annual thaw : but at a short distance from the surface, throughout Siberia, a bottom of perpetually frost-bound soil is met with. Gmelin the elder, in his travels, states that shortly after the foundation of the town of Yakutsk, in lat. 62^° north, at the end of the seventeenth century, the soil of that place was found to be frozen at a depth of ninety-one feet, and that the people were compelled to give up the design of sinking a well, a state ment corroborated in our days by the travels of Erman and Humboldt. Until very lately nothing was known respecting the thickness of the frozen surface ; but within these few years a merchant of the name of Schargin, having attempted to sink a well at Yakutsk, was 230 PHYSICAL GEOGRAPHY. about to abandon the project in despair of obtaining water, when Admiral Wrangel per suaded him to continue his operations till he had perforated the whole stratum of ice. This was done, and at the depth of 382 feet the soil was found very loose, and the temperature of the earth was 31° Fahrenheit. The external appearance of these cold districts is admirably depicted by a writer quoted by Berghaus. With painful feelings, he states, the traveller observes the trees diminishing in height the nearer he approaches the icy sea. At ninety German miles from the sea, erect and lofty larch trees afford a veil to expiring nature, but from this point their number diminishes, and they become small and crippled. The coating of moss that covers the tree is thicker than the stem itself ; but nothing can save it from the destroying breath of the north. Some thin birches endeavour to contend against this fearful foe, but they perish when scarcely sprung from the bosom of the earth, and 70° latitude may be assigned as the limit of the growth of trees. It is only the moss, the true child of the north, which thrives and blooms even in the midst of winter, and scantily covers a soil which has been barren for thousands of years. From the last tree to the frozen ocean extends an enormous desert covered with lakes and lagunes. Some of the lakes are large and deep, and rich in fish, their lofty banks consisting of level beds of earth and ice, the ice covering the earth. Throughout this region a death like silence reigns, seldom interrupted except by the summer birds of passage. We now proceed to notice the flat lands of the New Continent. A large portion of South America is only slightly raised above the level of the ocean. Supposing, as the effect of some particular attraction, the waters of the Atlantic to be raised fifty fathoms at the mouth of the Orinoco, and two hundred fathoms at that of the Amazon, the flood would cover over more than one-half of that part of the New World, and the billows of the sea would dash against the eastern slope or foot of the Andes, which is now nearly 2000 miles from the coast of Brazil. Comparatively low transverse ridges, running east and west, divide South America into three great districts. Through the northern district the Orinoco flows ; through the central, the Amazon ; and through the southern, the La Plata. The country on each side of these rivers consists of enormous levels, to which the terms Llanos, Selvas, and Pampas, are applied, distinguishing the regions bordering on these mighty streams, in the order in which they have been named. The Llanos border on the Orinoco, and are plains, including the vast area of 260,000 square miles, at the mean height of 200 feet above the level of the sea, sluggishly there fore bearing tributary streams to the great watercourse. The name is an abbreviation of loca plana, and was applied to them by the first Spanish conquerors, on account of their singular flatness. Humboldt has described the Llanos with great felicity, and presents us with the following graphic picture : — "The sun," he thus commences, "on our entrance into the basin of Llanos, stood almost in the zenith ; the ground, wherever it was naked and destitute of plants, was of a temperature which attained 48 or 50 degrees. No breeze was perceptible at the height on which we were sitting on our mules, yet there arose, in the midst of this apparent repose, an incessant cloud of dust driven by light breaths of wind which swept only the surface of the ground, and produced differences of temperature, which were imparted to the naked sand and the spots of grass. These sand- winds increase the suffocating heat of the air. Every grain of sand, hotter than the atmo sphere which surrounds it, beams on all sides, and it becomes difficult to measure the temperature without the grains of sand beating against the ball of the thermometer. All around us, the plains seemed to rise to heaven, and this vast and silent desert appeared to our eyes like a gea which is covered with sea-weed, or the alga? of the deep sea. Accord ing to the inequality of the mass of vapour floating in the atmosphere, and the alternating temperature of the breezes contending against each other, was the appearance of the horizon ; — ia some places clear and sharply defined, in others wavy, crooked, and, as it VALLEYS AND GREAT LEVELS OF THE EARTH. 233 exclusive property, and for her unfettered operations. The plain of the Amazon is, perhaps, destined to remain for ever a wilderness." South of the forest-covered plain of the Amazon, we come to the third great level of South America — the region of the Pampas, an Indian word signifying a flat, given to districts which are true steppes — plains rich in grass, but without trees. They extend in an almost uninterrupted band from latitude 15° south to 45°, or about 1800 geographical miles, by a width varying from 300 to 900 ; and while at one extremity we find the palm, at the other, where the ground is extremely low, it is covered with perpetual ice. Sir Francis Head describes the pampas, stretching from Buenos Ayres to the Andes, as a vast plain, divided into regions of different climate and produce. The first of these regions is covered with clover and thistles ; the second region produces long grass ; and the third region, which reaches the base of the Cordillera, is a grove of low trees and shrubs. The second and third of these regions exhibit nearly the same appearance throughout the year. The trees and shrubs are evergreens, and the immense plain of grass only changes its colour from gi-een to brown. But the first region varies with the four seasons of the year in a most extraordinary manner. In winter the leaves of the thistles are large and luxuriant, and the whole surface of the country has the rough appearance of a turnip-field. The clover in this season is extremely rich and strong ; and the sight of the wild cattle grazing in full liberty on such pasture is very beautiful. In spring the clover has vanished, the leaves of the thistles have extended along the ground, and the country still looks like a rough crop of turnips. In less than a month the change is most extraordinary ; the whole region becomes a luxuriant wood of enormous thistles, which have suddenly shot up to a height of ten or eleven feet, and are all in full bloom. The road or path is hemmed in on both sides ; the view is completely obstructed ; not an animal is to be seen ; and the stems of the thistles are so close to each other, and so strong, that, independently of the prickles with which they are armed, they form an impenetrable barrier. The sudden growth of these plants is quite astonishing ; and though it would be an unusual misfortune in military history, yet it is really possible, that an invading army, unacquainted with this country, might be imprisoned by these thistles before they had time to escape from them. The summer is not over before the scene undergoes another rapid change : the thistles suddenly lose their sap and verdure ; their heads droop ; the leaves shrink and fade ; the stems become black and dead ; and they remain rattling with the breeze one against another, until the violence of the pampero or hurricane levels them with the ground, where they rapidly decompose and disappear — the clover rushes up, and the scene is again verdant. Such, in the main, is Captain Head's description of the extraordinary spectacle, which has doubtless been annually exhibited by this division of the pampas ever since its emergence from the ocean under whose billows it once lay. It must not be imagined, however, that the region of the pampas displays uniformly this vigorous vegetation. There are large spaces which are absolutely sterile tracts of sand and stone, but sur rounded with districts sufficiently luxuriant to pasture enormous droves of cattle which are more or less under the dominion of man. The northern division of the western continent contains a single connected tract of flat country, which forms the central part of North America, reaching from the coasts of the Mexican Gulf to the inhospitable shores of Hudson's Bay and the Arctic Sea. This vast region, almost as large as the whole of Europe, is the site of two of the greatest river-systems of the earth, that of the Mississippi with its affluents, and that of the St. Lawrence with the chain of the Canadian Lakes. No prominent elevation appears between these rivers pursuing different directions, serving as a water-shed ; and as little observable is the elevation of the partition which separates the streams flowing to the St. Lawrence and to Hudson's Bay. Both have a very gentle descent, and proceed 234 PHYSICAL GEOGRAPHY. from unimportant heights above the level of the sea. Lake Superior is only 600 feet above the level of the ocean, Lake Erie 528 feet, and Lake Ontario 216 feet, while the plains about Cincinnati have scarcely an absolute height of 480 feet, and yet the Ohio is there 1400 miles from its confluence with the sea by means of the Mississippi. In this great district a person may have been born, may have lived to old age, and travelled much, without once seeing an elevation worthy of the name of mountain. It extends through all zones of vegetation, having palms and bamboos in its southern portions, while its northern margin, during great part of the year, is covered with snow and ice. Flint, the American geographer, classes under the three distinct aspects of the Wooded, the Barrens, and the Prairie country, the general surface of this territory, the Far West, as it is termed by the inhabitants of the Atlantic portion of the United States. In the timber region the trees are remarkable for the grandeur of their form and size. Fre quently there are but few low shrubs, and the large tall trees are branchless a consider able way up, their smooth straight trunks appearing like stately pillars. The rays of the sun playing upon the magnificent upper foliage, and glancing through it, give to the forest the aspect of a cathedral in which the light is modified by the stained windows, and falls in tinted streams upon the Gothic arches and columns. The Barrens, or barren grounds, exhibit an undulating surface covered with long coarse grass, interspersed with copses of hazel and underwood, and a few stunted oaks scattered here and there, which resemble the masts of ships seen at a distance. They are found east and west of the Mississippi, and occupy extensive spaces, but are chiefly situate along the margin of the Alleghany and Rocky Mountains, where they form a series of small plateaus. The remaining, and by far the most extensive division, is that of the Prairies, which exhibit no inconsiderable diversity of aspect. These are immense meadows, classed as wet or dry, or heathy, according to their character. The heathy prairies are covered with bushes of hazel and furze, small sassafras shrubs, with grape vines, and an infinite variety of flowers in the summer season. The wet prairies occur by the side of the great watercourses, and are scenes of exhaustless fertility, almost dead levels ; but they are found also apart from the rivers, and form insalubrious marshes, like the Dismal Swamp in Virginia, and the great morasses of Florida. The dry prairies constitute the most extensive class, and are for the most part destitute of springs, and of all vegetation but weeds, flowering plants, and grass. They are the plains over which the buffaloes range, without wood or water, on which the traveller may wander for days, beholding the heavens on every side sinking to contact with the grass, and hearing little beyond his own footfall. They have gently undulating and wavy surfaces, which has originated the name of the rolling prairies. " After a toilsome march," says "Washington Irving, " of some distance through a country cut up by ravines and brooks, and entangled by thickets, we emerged upon a grand prairie. . Here one of. the characteristic scenes of the ' Far West ' broke upon us. An immense extent of grassy, undulating, or, as it is termed, ' rolling ' country, with here and there a clump of trees dimly seen in the distance like a ship at sea, the landscape deriving sublimity from its vastness and simplicity. To the south-west, on the summit of a hill, was a singular crest of broken rocks, resembling a ruined fortress. It reminded me of the ruin of some Moorish castle crowning a height in the midst of a lovely Spanish landscape. The weather was verging into that serene, but somewhat arid season, called the Indian summer. There was a smoky haze in the atmosphere that tempered the brightness of the sunshine into a golden tint, softening the features of the landscape, and giving a vagueness to the outlines of distant objects. This haziness was daily increasing, and was attributed to the burning of distant prairies by the Indian hunting parties." The richer prairies are scenes of astonishing beauty during the months of vegetation, owing to the variety and hues of the flowering plants, VALLEYS AND GREAT LEVELS OF THE EARTH. 235 with their tall arrowy stems, and spiked or tassellated heads. Through the summer months there is a distinct succession of dominant colours, the prairie appearing like a carpet of purple velvet in spring, passing to one of red at midsummer, and gold in autumn. Striking examples of these districts in the western world, upon a small scale, appear upon the surface of the level land of Europe. Though this has already been cursorily noticed, yet, as a home territory, it deserves another glance. The great space extending from the shores of the Black to the coasts of the White Sea, and from the western foot of the Ural Mountains to the English Channel and the Atlantic Ocean, presents savannahs, primeval forests, barrens, morasses, and the most richly cultivated plains, alternating with each other in a manner the most diversified, inhabited in some parts by nations of the highest degree of intelligence, while in others nomadic tribes wander on its surface from pasture to pasture. Surprise has often been excited at the enormous droves of oxen, horses, and mules that feed upon the plains of America ; but the aggregate amount which find pasture upon the European levels is not less prodigious, the number of oxen, cows, and calves alone, sustained upon those flats of the Danube that are within the limits of the Austrian monarchy, being estimated at upwards of thirteen millions. The south and south-western parts of the vast Sarmatian plain, which includes nearly the whole of Eu ropean Russia, has large districts of rich black loam of almost incredible fertility. This is remarkably the case with the great wide plateau of Podolia and Volhynia, which abuts against the outliers of the Carpathian Mountains. " The traveller," says a very attentive observer, " who proceeds from the north to the south, sees it afar in the blue horizon, hails it as a happy island after having traversed for days together monotonous fields of sand, or the melancholy and gigantic morasses of Katner and Pinsk ; nor will he find himself deceived in his expectations. He reaches a region as rich and fruitful as it is kind and hospitable ; he finds lovely landscapes and beautiful tracts of country." The origin of the peculiar black vegetable earth which distinguishes this southern margin of the Sarmatian plain, has thus been intimated by Dubois. If we remember, he remarks, that this territory was in early times covered with a splendid growth of trees — that even at the time of Herodotus the Scythians cultivated it, rooting up the woods, according to their ancient usage, considering them as so many encroachments upon their tracts of pasture — that those nomadic races, the Tartars, who drove their numerous herds on this great highway of Oriental nations, inherited the Scythian aversion to trees; — if we remember these facts, we shall not be surprised at finding that these beds of thick black vegetable earth now form a mine of gold to the country. Westward, along the banks of the Vistula, between the town of Thorn and the sea, we have plains celebrated for their fertility and productiveness, which now fill the granaries of Dantzic with corn, and which the German knights rescued from the waves in the thirteenth century, and ren dered them integral portions of the continent by artificial mounds similar to those which at present, to a greater extent, defend them from the waters of the Baltic. The dyke of the plain of Marienburg, it is known, existed before the year 1397 ; and that of the plain of Thorn has now an extent of forty-five German miles, without including its numerous small windings and turns. Immediately contiguous are plains which remain in their original condition, and are only in part used as pastures, being overgrown with bushes, the haunts of wild animals. Here also lie the remains of one of the aboriginal forests of Lithuania, a waste of wood consisting of firs, pine-trees, and oaks, which man has seldom visited, and into the interior of which the axe of the woodman has never pene trated. It bears the name of Niezearow, or the " unknown country," as the number of stems which have fallen upon and across one another render it thoroughly impassable. An abundance of moose deer, bears, lynxes, and wolves inhabit this forest region, in the 236 1'IIYSICAL GEOGRAPHY. heart of Europe, which is analogous to the sclvas of the Amazon. Compared with the north of Germany, the spring here begins late, and is short ; the summer is foggy and stormy ; and the mean temperature lower than that of more northerly districts. Proceeding in a westerly direction, the flat land traverses the north of Germany, and here forms a series of ascents and descents from the shores of the Baltic to the foot of the Alps, in which however the ascent becomes more marked as the south is approached. A line drawn from the island of Usedom at the mouth of the Oder, through New Strelitz, Berlin, Leipsic, Greitz, Baireuth, Ratisbon, and Munich, to the Tegern Lake, divides* Germany into two parts, the east and west ; and along its whole extent, there is only a single mountainous tract to pass over, which commences at Greitz about the middle distance. Following this line from the north, the traveller gradually rises by a series of terraces, the loftiest of which, at whose southern margin the Alps with their high masses plunge into the depths beneath, stands about 1400 feet above the spot where he com menced his journey. The physiogonomy of the country through which he passes is of the most varied kind. At its northern extremity are the gently undulating hills of Usedom, with their beautiful and verdant forests, affording in open spots, on the one hand, a view of that billowy sea which only terminates with the sky, and on the other the tranquil waters of the mouth of the Oder are seen, with the coast of Pomerania, enlivened by numerous sails which the active commerce of Stettin sends into distant lands beyond the ocean, into other hemispheres and other climates. The coast of Pomerania is to a considerable extent an open cornfield, without a tree or bush, a fruitful solitude, wearisome from its sameness. Beyond, at the horizon, a sharp line arrests the eye, the heights of Mecklenburg, a district where the scene alters, and the abodes of a rich population appear, enclosed in fruitful gardens, around the capital of the beautiful country of New Strelitz. Farther towards the south the soil changes ; sand becomes the prevailing element, and woods of the gloomy pine and common fir intermingle with the meagre sand-fields on which man can only obtain a scanty subsistence from the earth. This is the prevailing character of the country through the Mark of Brandenburg, the whole of which is covered with erratic blocks, many of enormous size, which some great inundation has apparently borne hither from their native Scandinavian bed. Reaching the Elbe, a new soil commences on its southern bank ; luxuriant corn-fields appear, which only become more productive, till the fruitful fields of Leipsic open before us. The great plain we have been following from the Baltic, ends at Greitz, on the White Elster ; and, at the south bank of the river, the traveller ascends the first terrace of the plateau of Southern Germany. It is not, how ever, a ridge which he attains, but a plain, reaching to Gera, where he beholds before him plains again and again, which rise like terraces one above the other. Farther on, he wanders through narrow valleys overshadowed by the powerful stems of the red and white fir, leading to the foot of the mountain chain which abuts against the ramparts of Bohemia. The valley plain of the Maine is now entered, presenting variegated meadows, rich corn fields, the red roofs of innumerable villages ; and afterwards we proceed to the plateau of the Upper Palatinate, which, by its barrenness, strikingly contrasts with the region we have just left. The northern fir, here and there mixed with the pine, becomes again the prevailing tree ; and the country has all the aspect of the plains of Branden burg, till we arrive, by a wood of pines passing over a mountain ridge, within sight of the venerable Ratisbon. Wild and deep rushes the Danube past its walls, not so much splashing as foaming against the pillars of the lofty bridge which conducts us across a fertile plain, with wavy elevations, to the valley of the Isar. which forms only a moderate depression in it. Here, standing on some heights near the small town of Freising, the traveller sees on the southern horizon what he thinks at first a mere vapour in the air — a heap of clouds, the edges of which appear serrated. It is the Alps ! Over a plain more VALLEYS AND GREAT LEVELS OF THE EAKTII. 237 smooth and level than any which are observed in the north of Germany, we travel to the capital Munich, which, with all its palaces and monuments, stands in the midst of a large unattractive level, extending with few interruptions to the Tegern lake, one of the entrance gates of the Alps. The level land of the north of Germany extends westward through Holland, Belgium, and France ; and in the latter country it surrounds in a great arc, with but few inter ruptions, that system of mountains, Avhich, rising in Cevennes, extends to the Lower Rhine. Great diversity in the form and soil of the surface, and the nature of its cultiva tion, is the character of this part of the neighbouring kingdom, which, with fertile and most fruitful districts, exhibits true steppes and actual deserts. The following sketch of a portion of this flat land — that on the western coast — is indebted for several of its fea tures to the lively pictures of modern travellers. Setting out from the Pyrenees, and proceeding to Bourdeaux, we pass over the department of the Landes, the direct track lying through a wild sandy desert, in many parts too unproductive even for sheep walks, in others presenting forests of pine of vast extent. The peasantry live in solitary cabins ; employed in cultivating the soil where it is not absolutely sterile ; tending hardy sheep, or making charcoal in the woods ; traversing the deserts on stilts in order to pass the intervening morasses dry-shod. Reaching the wide and bay -formed mouth of the Gironde, in which its waters lose the wild tempestuousness which marks their early career in the Pyrenees, we meet with a country on the right bank, wliich in appearance is tolerably The Pyrenees from the Great Plain of Languedoc. rich, covered with plantations of vines, and sinking softly in innumerable hills down to the sea. The chain of sand on the sea-coast is bordered by a beautiful alternation of fields, woods, and meadows, with villages bearing the aspect of cleanliness and comfort, their white houses and green window-shutters contributing to the agreeable effect of the landscape. Here is the district of Saintonge, which, with its waving valleys and classic reputation, acquired in poetry the name of the Flower of France. Along the whole coast, light houses have been erected, that of the tower of Cordouan, built by order of Henry IV., being the most ancient and admired, and the most celebrated in France. It stands on a rock two miles out amid the waves, announcing the vicinity of a dangerous coast; and 238 PHYSICAL GEOGRAPHY. the fancy readily turns to it as a memorial of sorrow, on the grave of a city engulfed by the encroaching waters — the Novioregum of antiquity. A melancholy spectacle is presented farther north, towards Rochefort, that of flat barren wastes, and salt marshes, with here and there a spot planted with trees, and occasionally there is a village deserted and in ruins, high grass, and elder bushes mingling with its remains. It is hence with pleasure that the traveller descries the dome of the hospital and the walls of Rochefort ; but, notwithstanding its fresh and smiling aspect, and the pleasant murmuring of its large elms, the town has been literally snatched, at an immense cost, from the morass, and no sooner is it passed than the dismal swamp again appears. The whole road to La Rochelle is of a melancholy character, and especially so if traversed under a cloudy sky. It crosses a dreary steppe, of which the sea is the limit on one hand, and which is apparently boundless on the other. At distant intervals are a few tamarind trees ; or a lonely farm-house sends out its gloomy smoke ; or some conical hay ricks are passed, standing round a neglected barn ; or a meagre horse, with scanty mane, stands beside the road, and neighs at the approaching storm. The sea beats against the foundations of the road, and the sea-mews cross it, driven by the wind, their white wings contrasting strongly with the dark and louring clouds. Thus, at both extremities of the flat land of Europe, — the western, where it reaches the Atlantic, and the eastern, where it ends with the Caspian, — we find the same superficial aspect — a monotonous, desolate, and treeless waste. CHAPTER IV. CAVERNS AND SUBTERRANEAN PASSAGES. HEN we reflect upon the manner in which the solid crust of the earth appears to have been formed, upon the powerful upheaving force by which its elevated sites have been raised, and the posterior agency of subterranean gases, volcanoes, and earthquakes, it is natural to expect chasms in the surface of tremendous depth, spaces also in the interior which have not been filled up with mineral masses similar to the materials of the earth itself, but by water, air, or vapour, with those cavities of grotesque and romantic ap pearance that are found in mountainous re gions. There are few natural objects which have more awakened curiosity, or more strongly affected the imagination, than the hollow places, of various form and size, common in districts which have been subject to great physical dis turbance. Their seclusion and gloom — their fantastic architecture — the effect of torch-light upon their numerous crystallisations — the augmentation of sound and its reverberation — together with their unknown extent in many cases — all these causes CAVERXS. 239 contribute to invest the cavities of the earth with exciting interest ; nor is it strange to find them interwoven with the traditions and mythologies of unenlightened nations. On account of their sombre interior and strange outline being adapted to impose upon an ignorant populace, and give effect to religious observances, the priesthoods of antiquity localised in caverns their false divinities, and celebrated sanguinary rites upon the natural altars found in their recesses. A cave, with a priestess seated upon a tripod at its mouth, pretending to inhale a vapour from the interior which inspired a knowledge of future events, the gift of Apollo, was the original Delphian oracle, reverenced by the mind of Greece, and resorted to by the proudest monarchs of the ancient world. The cavern, along with the deep forest, commended itself to the primitive inhabitants of northern Europe by its mystery and gloom as an appropriate spot for the performance of a barbarous worship, and many local titles of such sites preserve the memory of their former uses. An instance of this we have in Thor's cave, or, as Darwin calls it, " The blood-smear'd mansion of gigantic Thor," a broad excavation on the face of a huge rock in the limestone district of Derbyshire, divided into two chambers, one beyond the other, with a detached stone at the further extremity, where the light of day is very much subdued. But in India the largest use has been made of caverns for religious purposes, and immense pains have been taken with their adornment, extension, and architecture, at Elephanta, Salsette, and Ellora, where there are elaborately Avrought temples constructed, probably out of small natural crevices in the rock. We shall now refer to a few of those cavities which are entirely the workmanship of nature, with whose form man has not intermeddled, and notice the principal phenomena which they exhibit. That extensive cavities exist in the interior of the crust of the globe is evident from the phenomena of volcanoes and earthquakes. They are not accessible to observation, but the repeated tremblings of the soil in various places, and experiments made of oscillations of the pendulum, point to the conclusion, that there are large underlying hollows, at no great distance from the surface, of which the superficial land forms the ^ , roof. The table-land of Quito, sur rounded by the most powerful volcanoes upon the earth, and the remarkable plain of Jorullo, are supposed to be ex amples of this. Condamine believed that a considerable portion of the former district was to be regarded as the dome of an enormous vault ; and Parrot has shown it to be highly pro bable, by a careful calculation, that a cavity of at least a cubic mile and a half exists beneath its surface. The rumbling noise, like that of distant thunder, which on the testimony of Humboldt usually precedes and accom panies 'the eruption of its volcanoes, affords evidence in favour of this sup position, and as an increase of the subterranean vacuity must be the necessary conse quence of every outbreak, it is not at all an improbable event, that the blooming landscape will ultimately fall in, and this piece of table-land become an immense depression. The quantity of material scooped out of the interior of the earth by volcanic action is Jorullo, Mexico. 240 PHYSICAL GEOGRAPHY. immense, and calculated to produce vacuities in which the largest mountains would have ample space. It has been estimated that Etna in one of its last most important erup tions, that of the year 1769, threw out a mass of lava equal in volume to a cone 5820 feet in height, and 11,640 feet in breadth, or nearly four times larger than Vesuvius. Fourteen such eruptions would produce a mass equal to Mont Blanc, reckoning from the level of the sea, and twenty-six such large eruptions have occurred since the twelfth century. In the year 1783, when the earthquake of Calabria occurred, the Skaptar volcano in Iceland poured forth a stream of lava fifty miles long, between twelve and fifteen broad, and from one to six hundred feet in thickness, which must have been equal to six times the mass of Mont Blanc, and two and a half times that of Chimbora9o. From the discovery of America to the year 1759, the plain of Malpais, a volcanic district in Mexico, had remained undisturbed, and was covered with plantations of indigo and sugar-cane at the latter period. In the month of June, a succession of earthquakes commenced, and on the night of September the 28th a tract not less than from three to four miles in extent rose up in the shape of a dome ; and six great masses suddenly appeared, having an elevation of from 1312 to 1640 feet above the original level of the plain. The most elevated of these is the volcano of Jorullo, which is continually burning, the projection of which, with its kindred masses, must have created a considerable subterranean vacuity, and probably the whole dome-shaped plain of Malpais is hollow. Hence, it is a common event, in countries subject to great volcanic activity, for portions of the surface to fall in, the subsidence frequently becoming the bed of a lake. A part of the forest of Ari pas in the Caraccas thus subsided in the year 1790; a lake was formed nearly half a mile in diameter, and from eighty to a hundred yards in depth, and for several months after the trees of the forest remained green under the water. In the same year, in Sicily, at Santa Maria de Nisremi, a portion of the country three Italian miles in circumference sank thirty feet deep. Occurrences of the same kind appear to take place in the depth of the sea, the falling in of its bed being indicated on the surface of the waters by their sudden retreat and violent agitation on their return. A remarkable example of this phenomenon took place at Marseilles, on June 28, 1812, when the water in the harbour suddenly sank, then rushed out with great rapidity, and returned with equal violence; a movement which was repeated several times, till the equilibrium was restored, occasioning considerable damage to the shipping. Instances of similar events are innumerable, which serve to prove the existence of cavities, both in the interior of the exposed crust of the earth, and those parts of it over which the ocean rolls. To Humboldt we are indebted for a large amount of information respecting the cavities which appear upon the surface, the chief differences of their form, the beds in which they are found, and the causes which may have originated them. In the primary rocks, caverns are relatively fewer than in the later deposits, while the oldest masses of the granite and gneiss formations are particularly destitute of them. The principal are wide fissures, sometimes of unknown depth, and those hollow passages which occur in Switzerland and Dauphine, called crystal caves, owing to their walls being richly furnished with pillars of rock crystal. Similar vacuities occur in the gneiss of the Pine mountain in the neighbourhood of Wiesenthal, but they are not important. In Sweden and Norway, the granite presents fissures and caves of extraordinary extent, and perfectly unexplored, hitherto ; such as the cave cf Marienstadt. the end of which is not known, and the enormous deep hole at Frederickstall, where a stone thrown in only gives the echo of its fall in a minute and a half or two minutes ; an observation which, if well founded, would give, on the calculation of Perrit, a precipitous depth of 59,049 feet, the highest estimate, or 39,SGG feet, the least ; that is, from twice to CAVERNS. 241 three times the height of Ghimbor*£O. It is the primitive limestone that supplies the most numerous examples of caves and grottos in the primary rocks ; and if these yield in point of size to the later limestone formations, this arises from the inferior extent of the primitive limestone, rather than from its incapacity to form caves. In the transition mountains, and those of stratified structure, it is still the limestone in which the more extensive caves are found, of which those of the Hartz, the splendid caverns of Derbyshire, and those of the Carpathians, are well known. Caverns most frequently occur in the mountains of stratified limestone; and among these, one of the most modern formations, the Jura limestone, is particularly distinguished, and was therefore termed the cavern-limestone by the early geologists. The celebrated caves of Franconia, the grotto of Notre Dame between Grenoble and Lyons, and many others, occur in this formation. That of Kirkdale, in Yorkshire, is in oolitic strata. Next to the limestone in the stratified formations, the so-called older gypsum which contains salt is the most abundant in caverns. They are of rare occurrence in the sandstone, have generally broad openings but of no great extent. Such are the Cow-stall in Saxony, and a few caves in Bohemia. In the volcanic rocks, cavern formations are very common, and one of the most splendid examples in the world occurs in the basalt, a rock of comparatively modern igneous origin. This is the well-known cave of Fingal, in the island of Staffa, a small island on the western coast of Scotland, composed entirely of amorphous and pillared basalt. The name of the island is derived from its singular structure, Staflfa signifying, in the Norwegian language, a people who were early on this coast, a staff, and, figuratively, a column. The basaltic columns have in various places yielded to the action of the waves, which have scooped out caves of the most picturesque description, the chief of which are the Boat cave, the Cormorant cave, so called from the number of these birds visiting the spot, and the great cave of Fingal. It is remarkable that this grand natural object should have remained comparatively unknown, until Sir Joseph Banks had his attention accidentally directed to it, and may be said to have discovered it to the inhabitants of South Britain. This great cavern consists of a lava-like mass at the base, and of two ranges of basaltic columns resting upon it, which present to the eye an appearance of regularity almost architectural, and supporting an irregular ceiling of rock. According to the mea surements of Sir Joseph Banks, the cave from the rock without is 371 feet 6 inches ; the breadth at the mouth, 53 feet 7 inches ; the height of arch at the mouth, 117 feet 6 inches; depth of water at the mouth, 18 feet ; and at the bottom of the cave, 9 feet. The echo of the waves which wash into the cavern has originated its Gaelic name, Llaimh-binn, the Cave of Music. Macculloch re marks : " If too much admiration has been lavished on it by some, and if, in consequence, more recent visitors have left it with disappointment, it must be recollected, that all descriptions are but pictures of the feelings of the narrator ; it is, more over, as unreasonable to expect that the same objects should produce corresponding effects on all minds, on the enlightened and on the vulgar, as that every individual should alike be sensible of the merits of Phidias and Raphael, of Sophocles and of Shakespeare. But if this cave were even destitute of that order and symmetry, that richness arising from multiplicity of parts combined with great ness of dimension and simplicity of style, which it possesses ; still the prolonged length, the twilight gloom half concealing the playful and varying effects of reflected Cave of Fingal. P 242 PHYSICAL GEOGRAPnY. light, the echo of the measured surge as it rises and falls, the transparent green of the water, and the profound and fairy solitude of the whole scene, could not fail strongly to impress a mind gifted with any sense of beauty in art or in nature, and it will be com pelled to own it is not without cause that celebrity has been conferred on the Cave of Fingal." Caverns occur in modern porphyry in the neighbourhood of Quito, and even in modern lavas, the ejection of which has taken place within the memory of man. Flinders has made us acquainted with caves in the lava of the Isle of France ; and in the lava of Vesuvius of 1805, Gay Lussac found several upon a small scale. But caverns of an enormous extent occur in the lava of Iceland, that of Gurtshellir, situated in the torrent which has flowed from Bald Yokul, being forty feet in height, by fifty in breadth, and nearly a mile in length. Beautiful black volcanic stalactites hang from the high and spacious vault, and the sides present a succession of vitrified horizontal stripes, a thick coating of ice clear as crystal covering the floor. Henderson, in particular, describes one spot, the grandeur of which surpassed all expectation, the light of the torches rendering it peculiarly enchanting. The roof and sides of the cave were decorated with the most superb icicles, crystallized in every possible form, many of which rivalled in minuteness the finest zeolites ; while from the icy floor rose pillars of the same substance, assuming all the curious and fantastic shapes imaginable, mocking the proudest specimens of art, and counterfeiting many well-known objects of animated nature. A more brilliant scene, says Henderson, perhaps never presented itself to the human eye, nor was it easy for us to divest ourselves of the idea that we actually beheld one of the fairy scenes depicted in Eastern fable. Among the forms under which caverns present themselves, Humboldt distinguishes three principal kinds, which essentially differ from each other, notwithstanding all their apparent irregularities. The first appear in the form of cracks or fissures, like empty veins of ore, of greater or less extent, but narrow and considerably prolonged, often penetrating far into the hard rock, and only reaching the day at one end. Eldon hole, in the Peak of Derbyshire, is an example of this class. This is a deep yawning chasm in the limestone strata, but no longer considered one of the wonders of the region, as its presumed unfathomable depths have been satisfactorily measured. In the reign of Queen Elizabeth, the Earl of Leicester is said to have hired a man to go down into it to ascertain its extent and form. The account of the adventure states, that he was let down about two hundred ells, and after he had remained at the length of the rope awhile, he was drawn up again, with great expectation of some discoveries ; but he came up senseless, and died within eight days in a phrensied condition. Cotton alludes to this circumstance in his rude English verses, — " Once a mercenary fool, 'tis said, exposed His life for gold, to find what lies inclosed In this obscure vacuity, and tell Of stranger sights than Theseus saw in hell ; But the poor wretch paid for his thirst of gain — For, being craned up with a distempered brain, A faltering tongue, and a wild staring look, He lived eight days, and then the world forsook." Eldon Hole is a fissure about sixty feet long, twenty wide, and two hundred deep. In the Philosophical Transactions for the year 1781, there is an account of the descent of Mr. Lloyd, who was let down with a rope by eight men, and found the light sufficiently strong at the bottom to allow him to read print. He discovered a fissure in the rock at the bottom, through which a strong current of air proceeded, but as the aperture was nearly filled up with huge stones, he could not examine it. A former owner of the CAVERNS. 243 pasture in which the chasm is situated, having lost cattle by falling into it, made the attempt to fill it up, and threw down many loads of stones without any visible effect, some of which were probably those which choked the aperture reached by Mr. Lloyd. The whole extent and actual depth of Eldon Hole have not therefore been ascertained. There is a second kind of caverns which are essentially distinguished from the first by the circumstance that they reach the daylight at both ends, piercing through the rocks in which they are situated, and forming natural shafis. Their appearance is very remarkable when they occur on the top of isolated mountain-peaks, or of independent masses of rock ; and when they are so straight that the day-light appears through them, they present a very remarkable aspect, and have been designated by the name of transparent caverns. On this account, the so-named Martin's hole is particularly celebrated. It penetrates the Tschingel-peak, one of the highest mountains of the Dodi chain ; and twice in the year, in March and in September, the sun appears as if through a pipe, and gives to the valley beneath a highly singular and pleasing light. A similar phenomenon has been described by Pontoppidan as occurring in Norway, where there is a perforation of the mountain of Torghatten in Helgeland, of fifty fathoms in height, and a hundred fathoms in length, through which the daylight appears. Like phenomena present themselves at the hollow stone of Muggendorf ; likewise in Saxon Switzerland, and a, whole series of these per forations occur on the coast of the island of Heligoland, and on the coast of New Zealand. The third and most frequent form of caverns is unquestionably that in which there is a series of extensions of nearly similar height and direction, which are connected with each other by passages of greater or less extent. This is the form of the caverns of the Hartz, the cave of Caripe visited by Humboldt, of Antiparos, and of the Peak of Derbyshire, __^^_ the entrance to which, with the castle on its summit, is here represented. This is also the form of the more im portant caves of Franconia. The extent of these penetra tions into the mountains, in particular of such as are si tuated in limestone, is often very extraordinary. In many of them the extremity has never been reached ; and it appears from con- curreat testimony that some of them have been explored for more than a mile in length. In this respect, the cave of Adelsberg, six miles from Trieste, is mentioned as the greatest of all, excel ling all known caverns, not only in length, but in height. Deep abysses of five and six hundred feet often occur in it ; and in one of these, it was found necessary to give up the attempt to proceed farther. The entrance resembles a fissure in a huge rock caused by an earthquake. Here torches are always lighted to conduct visiters. The cavity itself Pcveril of the Peak's Castle, with the mouth of the Cave. The Cupola Cavern. PHYSICAL GEOGRAPHY. seems as if divided into several large halls and other apartments. The vast number of pillars by which it is ornamented by nature gives it a superb appearance; for they are as white as snow, and have a kind of transparent lustre. The bottom is of the same material ; so that a person may imagine he is walking among the ruins of some stately palace, amidst noble pillars and columns, partly mutilated and partly entire. From the top, sparry icicles are seen every where suspended ; in some places resembling wax tapers, which, from their radiant whiteness, appear extremely beautiful. Here occurs that extraordinary animal the Proteus, in shape be tween a lizard and an eel, transparently white, with a tinge of rose colour about the head. It adds, as Davy remarks, one instance more to the number already known of the wonderful manner in which life is produced and perpetuated, even in places which seem the least suited to organ ised existences — an animal to whom the pre sence of light is not essential, living indifferently in air and in water, on the surface of the rock, or in the depths of the mud. Of an analogous kind is the Peak cavern in Castleton Dale, the approach to which is in the highest degree magnificent. The traveller passes through a chasm between two ranges of perpen dicular rocks, having on his left a rivulet which issues from the cave, and pursues its splashing course over craggy and broken masses of lime stone. A vast mass of rock suddenly appears before him, with the mouth of the cavern, which assumes the form of a depressed arch, a hundred and twenty feet in width, forty-two in height, and about ninety in receding depth. At the first entrance, a spectator is surprised to find that a number of twine makers have established their residence and manufactory within this gulf ; and their rude appearance and machines singularly combine with the sublime features of the natural scenery. After proceeding about thirty yards, the roof becomes lower, and a narrow passage is reached where the blaze of day, which has been gradually softened into twilight, wholly disap pears, and all further researches must be prose cuted by torch-light. After penetrating twenty or thirty yards in a stooping posture, there is a spacious opening, beyond which is the margin of a small lake called the First Water, the over- CAVERNS. 243 hanging rock descending in one place to within twenty inches of its surface. The lake is crossed in a boat or skiff, partly filled with straw, in which the passenger lies down, and is conveyed to the other side, where a spacious vacuity opens 220 feet in length, 200 feet broad, and in some parts 120 feet high ; but from the want of light, neither the roof nor the sides of this great cavity can be plainly discerned. Proceeding onwards by the side of the Second Water, there is a projecting pile of rocks popularly called Roger Rain's House, on account of the water incessantly dripping from the crevices of the roof. Beyond this, another hollow opens, called the Chancel, where the rocks appear much broken, and the sides are covered with stalactical incrustrations. Here the stranger is generally surprised by an invisible vocal concert, which bursts in wild and discordant tones from the upper regions of the cavern, where a group of women and children are stationed for the purpose, the inhabitants of some of the huts at the entrance. After leaving the Chancel, and passing the Devil's Cellar, and the Half-way House, the path leads beneath three natural arches to another vast concavity, termed Great Tom of Lincoln, from its resemblance to a bell. Here, under the influence of a strong light, the arrangements of th j rock, the spiracles in the roof, and the flowing stream, produce a striking scene. From this point the vault gradually descends, the passage contracts, and at length leaves only room sufficient for the stream. The entire length of this great excavation is 2250 feet, and its depth from the surface of the mountain about 620. A striking effect is frequently produced by the explosion of a small quantity of powder, wedged into a crevice of the rock, the report of which rolls along the roof and sides like a heavy and prolonged peal of overwhelming thunder. On returning from this dark recess, the effect of the light is singularly impressive. The rocks appear as if highly illuminated, and the plants and mosses upon them so vividly green, as to produce the impression that the sun must be shining brilliantly upon them, when the day is really dull and hazy. The Peak cavern is thus an example of a succession of great chambers connected together by narrow passages ; and when we remember the soluble nature of the stone, and the stream that flows through it, there can be no doubt that, if not formed altogether by the action of water, it yet owes its present condition to that agency. A more extraordinary spot, perhaps, is in the neighbourhood, at the foot of the TTinnats, or Windgates, called also the " portals of the winds," a deep and narrow inclined chasm, about a mile in length, the lower descent of which commands a fine view of the beautiful vale of Castleton. Here is the Speed\vell mine, an artificial excavation, leading to a great natural cavern. After descending upwards of a hundred steps, and reaching the blackness of darkness, the visitor embarks upon a canal so narrow as to be able to touch the rock on both sides, and the ceiling above. Proceeding along this channel, which is not far short of half a mile in length, the guide pushing along the boat, an immense vacuity in the mountain is reached, and landing upon a ledge of rock, the scene becomes indescribably strange and appalling with the aid of a Bengal light. On the one hand there is an abyss of unknown depth, appropriately called the Bottomless Pit, into which the water from the level falls with a startling sound, and which swallowed up forty thousand tons of material in the excavation of the mine. On the other hand an enormous cavity opens above, the ceiling of which no light can reach, for rockets have been here let off, and have given out their brilliant corusca tions as freely as from the surface of the earth. Humboldt describes a somewhat dissimilar but very remarkable cavern in the western world, in the province of New Andalusia, not far from the convent of Caripe, called the Cavern of the Guacharo — the name of a class of nocturnal birds who make it their abode. The exterior of the place was majestic even to one accustomed to the picturesque scenery of the Alps. He had visited the Peak Cavern, and was acquainted with the different caves 246 PHYSICAL GEOGRAPHY. of Franconia, the Ilartz and Carpathian mountains ; and the uniformity generally observ able in all these, led him to expect a scene of a similar character in that which he explored in the New World : but the reality far exceeded his expectations ; for, if the structure of the cave resembled those he had elsewhere witnessed, the majesty of equinoc tial vegetation gave an individual character and indescribable superiority to the entrance of the Cavern of the Guacharo. The entrance is a vaulted arch, eighty feet broad and seventy -two feet high; the steep rock that surmounts this opening is covered with gigantic trees, mixed with creeping and climbing plants and shrubs, brilliant with blos soms of the richest colours and the most varied forms. These form natural festoons, which hang from the mouth of the cave, and are gently agitated by the passing currents of air. Among them Humboldt enumerates a Dendrobium, an orchideous plant, with golden flowers spotted with black, and three inches long ; a Bignonia, with a violet blos som ; a purple Dolichos ; and a magnificent Solandra, the deep orange flower of which has a fleshy tube four inches long. But this luxuriant vegetation was not alone confined to the exterior. The traveller, on following the banks of a subterranean stream into the grotto, beheld them, with astonishment, adorned for thirty or forty yards with the Praga palm tree, plantain-leaved heliconias, eighteen feet high, and arms that resembled trees in their size ! It was not found necessary to light their torches till they had reached the distance of 430 feet, owing to the continuous direction of the cavern, which allows the light of day to penetrate thus far ; and when this began to fail, the hoarse cries of the nocturnal birds began to be audible from a distance. The shrill discordant noise made by thousands of these birds, brought from the inmost recesses of the cave, and rever berated from the arched roofs, formed an indescribable clamour. The Indian guides, by fixing torches to the ends of long poles, showed the traveller the nests of the bird, which were constructed in funnel-shaped holes, with which the roof of the grotto was pierced in all directions, and generally at about sixty feet high. Still pursuing the course of the river, the cavern preserved the same width and height to the distance of 1458 feet from the mouth. The traveller, on turning round, was struck with the singularly beautiful appearance which a hill covered with the richest vegetation, immediately fronting the entrance of the grotto, presented. This, brilliantly illumined by the sun's rays, and seen through the vista of the dark cave, formed a striking contrast to the surrounding ob scurity ; while the large stalactites depending from the roof were relieved against the lumi nous back-ground of verdure. After surmounting, with some difficulty, an abrupt rise in the ground where the stream forms a small cascade, he found that the cave diminished in height to forty feet, but retained its original direction. Here a blackish mould was found, either brought by the rivulet, or washed down from the roof by the rain-water which penetrates the crevices of the rock ; and in this he found seeds growing, which had been brought thus far by the birds, but so altered by the deprivation of light, that the species of plant, thus produced under such unfavourable circumstances, could not even be recognised. It was found impossible to persuade the Indian guides to advance further. The cries of the birds, rendered still more horrible by the contraction of the cave, had such an effect on their minds, that they absolutely refused to proceed ; and, to the regret of Humboldt, he was compelled to retrace his steps. Caverns, especially those which are situated in limestone, commonly present the formations called stalactites, from a Greek word signifying distillation or dropping. The manner of their production admits of a very plain and simple explanation. They proceed from water trickling through the roofs containing carbonate of lime, held in solution by carbonic acid. Upon exposure to the air the carbonic acid is gradually disengaged, and a pellicle of lime is deposited. The process proceeds, drop after drop, and, eventually, descending points hanging from the roof are formed, resembling icicles, which are com- CAVERNS. 247 posed of concentric rings of transparent pellicles of lime, presenting a very peculiar appearance, and, from their connection with each other, producing a variety of singular shapes. These descending points are the stalactites properly so called, from which the stalagmites are to be distinguished, which cover the floors of caverns with conical inequalities. These are produced by the evaporation of the larger drops which have fallen to the bottom, and are stalactites rising upwards from the ground. Frequently, in the course of ages, the ascending and descending points have been so increased as to meet together, forming natural columns, a series of which bears a striking resemblance to the pillars and arches of Gothic architecture. The amount of this deposition which we find in caverns capable of producing it, is, in fact, enormous, and gives us an impressive idea of their extraordinary antiquity. The grotto of Antiparos — one of the islands of the Grecian Archipelago — is particularly cele brated on account of the size and diversity of form of these deposits. It extends nearly a thousand feet beneath the surface, in primitive limestone, and is accessible by a narrow entrance which is often very steeply inclined, but divided by level landing-places. After a series of descents, the traveller arrives at the Great Hall, as it is called, the sides and roof of which are covered with immense incrustations of calcareous matter. The purity of the surrounding stone, and the thickness of the roof in which the unfiltered water can deposit all impure admixtures, give to its stalactites a beautiful whiteness. Tall pillars stand in many places free, near each other, and single groups of stalagmites form figures so strongly resembling plants, that Tournefort endeavoured to prove from them a vege table nature in stone. The remark of that intelligent traveller is an amusing example of over confidence: — " Once again I repeat it, it is impossible this should be done by the droppings of water, as is pretended by those who go about to explain the formation of congelations in grottoes. It is much more probable that these other congelations we speak of, and which hang downwards or rise out different ways, were produced by our principle, namely, vegetation." The sight of the whole is described, by those who have visited this cavern, as highly imposing. In the middle of the Great Hall there is a remark ably large and fine stalagmite, more than twenty feet in diameter, and twenty-four feet high, termed the Altar, from the circumstance of the Marquis de Nointel, the ambassador from Louis XIV. to the Sultan, having caused high mass to be celebrated here in the year 1673. The ceremony was attended by five hundred persons; the place was illu minated by a hundred large wax torches ; and four hundred lamps burned in the grotto, day and night, for the three days of the Christmas festival. This cavern was known to the ancient Greeks, but seems to have been completely lost sight of till the seven teenth century. Some of the caves of France and Germany have a high reputation for the number and beauty of their deposits ; but the finest examples are found in the Cave of Adelsberg, to which reference has been made. The stalagmites here have formed two bridges over the subterranean river, which are situated almost a mile apart from each other, the inner one of which hangs suspended from eighty to a hundred fathoms over the abyss. An American visitor graphically describes some of the principal objects : — " We advanced with ease," he states, " through the windings of the cavern, which at times was so low as to oblige us to stoop, and at times so high that the roof was lost in the gloom. But every where the most wonderful varieties of stalactites and crystals met our admiring view. At one time we saw the guides lighting up some distant gallery far above our heads, which had all the appearance of verandahs adorned with Gothic tracery. At another, we came into what seemed the long-drawn aisles of a Gothic cathedral, bril liantly illuminated. The whimsical variety of forms surpasses all the powers of descrip tion. Here was a butcher's shop, which seemed to be hung with joints of meat ; and there, a throne with a magnificent canopy. There was the appearance of a statue with a 248 PHYSICAL GEOGRAPHY. bearded head, so perfect that you could have thought it the work of a sculptor ; and further on, toward the end of our walk, the figure of a warrior with a helmet and coat of mail, and his arms crossed, of the illusion of which, with all my efforts, I could rot possibly divest my mind. Two stalactites, descending close to each other, are called, in a German inscription over them, with sentimentality truly German, ' the union of two hearts' The resemblance is certainly very striking. After passing ' The Hearts,' we came to the * Ball Room.' It is customary for the inhabitants of Adelsberg, and the sur rounding country, to come on Whit-Monday to this grotto, which is brilliantly illumi nated ; and the part called the ball room is actually employed for that purpose by the peasantry. A gallery, very appositely formed by nature, serves the musicians for an orchestra ; and wooden chandeliers are suspended from the vaulted roof. It is impossible for me to describe minutely all the wonderful varieties ; the ' Fountains' seeming, as they fall, to be frozen into stone ; the ' Graves,' with weeping willows waving over them ; the ' Picture,' the ' Cannon,' the ' Confessional,' the ' Pulpit,' the ' Sausage-maker's Shop,' and the ' Prisons.' I must not omit mentioning one part, which, though less grand than many others, is extremely curious. The stalactites have here formed themselves like folds of linen, and are so thin as to be transparent. Some are like shirt-ruffles, having a hem, and looking as if they were embroidered ; and there is one, called the ' Curtain,' •which hangs exactly in natural folds like a white and pendent sheet. Every where you hear the dripping as of a continual shower, showing that the mighty work is still going on, though the several stages of its progress are imperceptible. Our attention was so excited, that we had walked two hours without feeling the least fatigue, or being sensible of the passage of time. We had gone beyond the point where most travellers had stopped, and had been rewarded for it by seeing stalactites of undiminished whiteness, and crystals glittering, as the light shone upon them, like unnumbered diamonds." Stalactical depositions vary in colour according to the nature of the surrounding rocks, and Hurnboldt remarks in general that the formations occur more beautifully and completely in proportion as the caves are narrow and enclosed, since the deposition of crystals is less disturbed by the circulation of the surrounding air. On this account those of the wide open cavern of Caripe, which he explored, were far inferior to the stalactites of Adelsberg. In our own country the spot most remarkable for these formations is the Blue John mine, another of the celebrated places of the Peak, near its great cavern. This is a natural cavity, worked as a mine for the sake of obtaining the elegant fluor spar which gives its name to the site, and which is here found in small detached pieces in the limestone rock. Rude steps, leading downwards about sixty yards, conduct to a series of caverns and passages encrusted with depositions of lime, which have assumed a variety of interesting forms. In our illustrated instance, sta lactites, of a delicate pearly yellow colour, of fine texture, and fantastically varied one from the other, have grown downwards until they rested upon some shelf of a lower stratum, probably of earthy matter. Arriving at such a plane, the waters in future spread more widely around, forming a deposit, and connecting the former stems with an inferior tablet of similar composition. The earthy or mineral stratum having been by some chance removed, the fairy columns attached to their kindred floor now remain suspended in middle space. These are graphically termed " the Organ." It is much to be regretted that a Continental reproach against us, that of an Englishman's eyes being in his fingers, here receives an illustration of its truth. Some unprincipled and vagabond sight-seers have wantonly mutilated this rarity, and deprived it of its earlier proportions, for which cause the relics are now upbraidingly exhibited in a rude wooden cage. Here, as at Antiparos, the principal subterranean apartment is termed the "Hall," a wide and lofty cavity, such as imagination conceives CAVERNS. 249 would be a fitting home for the romantic outlaws pictured by Salvator Eosa, or described in the pages of Schiller. In this spot, not a long time ago, a popular Organ, Blue John Cavern. nobleman, who prosecuted adventurous researches in the most dangerous recesses of the mine, feasted a multitude of his friends, and made the wet rock resound to the toasts and sentiments imported from a more fashionable atmosphere. In a certain direction from this grand focus the visiter is led to a narrower and more irregular space, presenting a towering cupola, the grandeur of whose shivered sides can only be exhibited by drawing upwards, with cord and pulley, a round of lighted candles supplied by the conductor : these illuminate successively the varied and peculiar stages of the internal surface. The perpetual waters which trickle down have left a residuum of lime, which has been moulded, by accident, and by industrious and gentle operation, into a thousand free tresses and waving bands. The whole is fashioned by Nature with less of the abrupt form which characterises the congelation of fountain streams by cold, and presents a grotesque enamel of exquisite polish and gracefulness, giving to the artificial plain or coloured lights, uplifted within the conical abyss, beautiful reflections from its unrivalled crystallised surfaces. Frequently, while attention is riveted to the precinct of gloom and awful solitude, a chaunt of voices is heard from the summit of the dome, accessible by hidden performers from other avenues of the mine. The fleeting and distant expression of sound, with the mournful intervals of the strain, seems like a song of captive spirits, obedient to the rigid discipline of some invincible gnome. The temperature of caverns exhibits great diversities, dependent upon their extent and form, and that of the same cavern will greatly vary at different seasons. In those which are dry and deep, covered with a thick stony roof, and withdrawn from the influence of the alteration of the external air, by having only a limited opening, the temperature can vary but little, and will continue through the whole year at nearly the same degree of warmth which is peculiar to their geographical situation. Before the warmer air of summer has so penetrated the roof that the temperature of the cavern can be somewhat 250 PHYSICAL GEOGRAPHY. raised, the cooler air of the autumn and of the winter begins to penetrate ; but before this lower temperature can establish itself, it is again overtaken by the warmth of the fol lowing spring and summer. The consequence of all this is a temperature subject to little alteration, but lower than the mean temperature of the surrounding atmosphere. The ancient Romans, hence, according to Seneca, were accustomed to erect their country seats in the vicinity of those natural cavities which abound about the capital, for the purpose of enjoying their refreshing chilliness in the summer season. It was in one of these volcanic caverns that Tiberius was nearly destroyed while at supper ; for, during the banquet, the roof suddenly gave way, and buried several of his attendants beneath its ruins, when Sejanus threw himself upon the emperor to preserve him from the falling stones. Many caverns, however, vary greatly in their temperature, and exhibit the appa rently strange anomaly of being cold when the external air is warm, and warm when it is cold, in some instances carrying this contrast to the extreme, so as to be coated with ice amid the heat of summer, and affording a comfortable warmth amid the cold of winter. In the neighbourhood of Szelitze, a village of Hungary, there is a cave in the transition limestone of the Carpathians which displays this phenomenon. The country in the vicinity abounds with woods, and the air is sharp and cold. The entrance of the cavern, which fronts the north, is eighteen fathoms high, and eight broad ; consequently, wide enough to receive a large supply of external air, which here generally blows with great violence ; but the subterranean passages, which consist entirely of solid rock, winding round, stretch away farther to the north than has been yet discovered. In the midst of winter the air in this cavern is warm ; but in summer, when the heat of the sun without is scarcely supportable, the cold within is not only very piercing, but so intense that the roof is covered with icicles of great size, which, spreading into ramifications, form very grotesque figures. When the snow melts, in spring, the inside of the cave, where its surface roof is exposed to the sun, emits a pellucid water, which immediately congeals as it drops, and thus forms the above icicles, and the very water that drops from them on the sandy ground freezes in an instant. It is even observed that the greater the heat is without, the more intense is the cold within, so that in the dog days all parts of this cavern are covered with ice, which the inhabitants use for cooling their liquors. The quantity of ice is so great that a narrator estimates that it would require six hundred waggons to remove it in a week. In autumn, when the nights grow cold and the heat of the day begins to abate, the ice in the cavern begins to dissolve, so that by winter no more ice is seen. The cavern then becomes perfectly dry, and has a mild warmth. At that season it is the haunt of swarms of flies, gnats, bats, owls, and even of hares and foxes that resort hither, as to their winter retreat, and remain till the return of spring. An instance almost as singular occurs at Besan9on, in a grotto which extends 364 feet into the rock, the mouth of which, like that of Szelitze, is towards the north, and covered with vegetation. During the whole summer this cavern contains masses of ice, which melt away in October and November. This apparently anomalous phenomenon is supposed to be capable of being explained by the relation which subsists between the moisture in these caverns and the external air. When it is hot and dry outside, as in summer, evaporation takes place, and by this means a considerable degree of warmth is withdrawn from the enclosed air, the vapours making their escape through the openings, and through fissures in the roofs. The greater the exterior temperature the more vigorously the evaporation is carried on, producing a degree of cold in the interior which may sink beneath the freezing point, just as in the greatest heat we can most readily freeze water if we surrround it with ether. It is upon this principle that travellers, in some regions, are accustomed to cool their drinks, which they bury in CAVERNS. 251 the earth, and light a quickly blazing fire over it, when the desired coolness is produced. On the contrary, the more the warmth and dryness of the external air are diminished, as in winter, the less will be its capability to promote evaporation in the cavern, the warmth contained in the air will no longer be absorbed, and the ice which has been produced must melt. The cooling in these caverns, however, so as to sink below the freezing point, can only occur where there is a certain relation, which but rarely subsists, between the openings and the evaporating surface of the interior. If the opening is too large, too much warm air is introduced, and the temperature of the interior is thereby much more increased than it can be diminished by evaporation. If it is too small, the vapours cannot withdraw themselves fast enough, and the evaporation is lessened, because the surrounding air is saturated with moisture. The ice-caverns, therefore, are com paratively rare ; but, in addition to those named, there is a cave at Vesoul, in France, where a stream flowing through it is frozen over in summer, and clear of ice in winter. Sir Roderick Murchison, in the course of his geological surveys in Russia, met with a freezing cavern near the imperial salt-works at Iletski, to the south of the Ural mountains, situated at the southern base of a hillock of gypsum, one of a series of natural hollows used by the peasantry for cellars or stores. The cave in question is however the only one in the district which possesses the singular property of being partially filled with ice in summer, and of being destitute of it in winter. " Standing on the heated ground and under a broiling sun, I shall never forget," he remarks, " my astonishment when the woman to whom the cavern belonged unlocked a frail door, and a volume of air so piercingly keen struck the legs and feet, that we were glad to rush into a cold bath in front of us to equalise the effect." Three or four feet within the door, and on a level with the village street, beer and quash were half frozen. A little further the narrow chasm opened into a vault fifteen feet high, ten paces long, and from seven to eight feet wide, which seemed to send off irregular fissures into the body of the hillock. The whole of the roof and sides were hung with solid undripping icicles, and the floor was covered with hard snow, ice, or frozen earth. During the winter all these phenomena disappear ; and when the external air is very cold, and all the country is frozen up, the temperature of the cave is such, that the Russians state they could sleep in it without their sheep-skins. There is another circumstance of high interest disclosed by the interior of many caverns, the occurrence of extinct animals of the ancient earth ; on which account these receptacles have obtained the name of zoolithes or bone caverns. These sites are observed in almost every country of Europe and America, but the fact was not much known till the late Dr. Buckland published the result of his investigations. He made it the subject of his peculiar study, and with great felicity, illustrated the light which it throws upon the ancient condition of the earth, and the changes which the surface has undergone. His researches into the condition of a cave discovered in 1821 at Kirkdale in Yorkshire are highly valuable, and deserve a notice here. Its mouth had long been choked up with rubbish, and overgrown with grass and bushes, but was accidentally found by some workmen. The cave is situated on the older portion of the oolite forma tion (in the coral rag and Oxford clay) on the declivity of a valley. It extends as an irregular narrow passage 250 feet into the hill. There are a few expansions, but scarcely high enough to allow a man to stand upright. The sides and floor were found covered with a deposit of stalagmite, beneath which there was a bed of from two to three feet of fine sandy and micaceous loam, the lower portion of which in particular contained an innumerable quantity of bones, with which the floor was completely strewn. The greatest part of them were very well preserved, and still retained a great portion of their natural gluten, in consequence of the peculiar nature of their investiture. The animals 252 PHYSICAL GEOGUAPnY. to which they belonged were the hyaena, bear, tiger, and lion, elephant, rhinoceros, hippopotamus, horse, ox, deer of three species, water-rat, and mouse, belonging wholly to extinct species, and the same with those with which we are acquainted in the steppes of Asia. The most plentiful of all were the remains of the hyaena, and from the amount which he saw, Buckland estimated the number of the individ uals interred here to be between two and three hundred. The animal must have been one half larger than the living species, in its structure resembling the hyaena of the Cape. The bears, which were less abun dant, belonged to the large cavern species, which, according to Cuvier, was of the size of a large white horse and about eighteen feet in length. The elephants were the Siberian mammoth. Of the stags the largest was of the size of the moose deer. Of the ox two species were distinguished, and its bones were most frequent next to those of the hyasna. All these bones lay irregularly strewed one with another, but those of the largest animals were in the most remote and narrowest corners, into which they never could have pene trated while living. The teeth, and the hard marrowless bones of the extremities, as well as those of the fore and hind feet, were uninjured : these were so numerous that they must have belonged to a much greater number of individuals than could be estimated as belonging to the other bones. Many of the bones bore marks which exactly corresponded with the form of the incisor teeth of the hyaena, and the broken horns of the stag were evidently marked by gnawing. These facts warranted the con clusion, that the hyaenas must have lived for a long time in this cave, and have dragged the bones of the larger animals, particularly the oxen, into this den, as their prey. The supposition was confirmed in the most striking manner by a variety of other facts. Dr. Buckland found that bones which he caused to be gnawed by living hyaenas had exactly the same appearance as those found in the cavern, and the teeth and harder bones were thrown aside by them. He even found in great abundance excrements of the hyaena, which offered the closest resemblance to those of the living animal. From the facts described, it appears that the Kirkdale cave was for a long series of years a den inhabited by hyaenas, who dragged into its recesses the other animal bodies whose remains are there commingled with their own, — some great catastrophe causing an inundation in this region which destroyed the whole race. Similar zoolithic caverns occur in the following places in our own country : — 1. Kent's Cavern, in the limestone of North Devon, about a mile from Torquay. It is said to be nearly six hundred feet long, varying in width from two to seventy feet, and in height from one to six yards. The bones of extinct species of animals are found buried in a mass of mud, covered over with a crust of stalagmitic formation. From certain appear- CAVERNS. 253 ances in this cavern, it seems to have been in former times the habitation of man, per haps the bandit's home. 2. Cave near the village of Hutton in the Mendip Hills. This A SL is a series of cavernous tba. chambers found by the la bourers in working for ochre, which occurs in fissures of the mountain limestone. In the first chamber, about twenty feet square and four high, a large stalactite de pends from the roof in the centre, and beneath a stalag mite rises from the floor, nearly touching it. The bones from this cavern are those of the elephant, horse, ox, deer, bear, and hog. 3. Cave at Balleye, near Wirks- worth. Bones and molar teeth of the elephant were discovered here in a cavity Kent's Cave, near Torquny. Of mountain limestone by the lead miners, mentioned in the following record of a workman : — "In sinking for lead at Baulee, within two miles of Wirksworth, A. D. 1663, they came to an open place as large as a church, and found a skeleton reclining against the side, so large that his brain-pan would have held two strike of corn, and so big that they could not get it up without breaking it. My grandfather having a share in the said mine, they sent him a tooth, weighing four pounds three ounces. — George Mower." Some of these remains are still preserved. 4. Dream Cave, near Wirksworth. This was likewise dis covered by the miners in pursuing a vein of lead. After sinking about sixty feet through solid mountain limestone, they came to a large cavern filled with argillaceous earth and stony fragments. Here were found the remains of a rhinoceros, in a high state of preservation. They belonged apparently to the same individual, and formed probably an entire skeleton, though several parts were wanting, having been separated from the rest through the subsidence of the mass in which they were imbedded into an underlying hollow, owing to the workmen disturbing the site. Bones of deer and frag ments of horns were found in the same spot, all of which are now deposited in the Oxford Museum. 5. Cave on Derdham Down, near Clifton ; a fissure which contained frag ments of stone and stalagmite, with bones incrusted with stalactitic matter, among which was a fossil joint of the horse. 6. Caves at Oreston, near Plymouth. Several caverns were discovered in removing materials for the construction of the Breakwater from a hill of transition limestone. They contained bones belonging to a species of rhinoceros, the tiger, hyaena, horse, ox, wolf, and deer. 7. Cave of Crawley Rocks, near Swansea. This cavity was accidentally intersected in working a quarry. It has now been entirely cut away. Various parts of the elephant, rhinoceros, hyaena, ox, and stag were found in it. 8. Caves of Paviland. Two cavities occur in a lofty cliff of limestone facing the sea on the coast of Glamorganshire, which the waves reach in considerable storms. The remains of an immense number of animals of extinct species have been found in .them. It is clear from these facts, that anciently, as Dr. Buckland remarks, " extinct species of hyaena, tiger, bear, elephant, rhinoceros, and hippopotamus, no less than the wolves, 254 PHYSICAL GEOGRAPHY foxes, horses, oxen, deer, and other animals which are not distinguishable from existing species, had established themselves from one extremity of England to the other — from the caves of Yorksliire to those of Plymouth and Glamorganshire — whilst the diluvial gravel beds of "Wanvicksliire, Oxford, and London, show that they were not wanting also in the more central parts of the country ; and M. Cuvier has established, on evidence of a similar nature, the probability of their having been spread in equal abundance over the continent of Europe. But it by no means follows, from the certainty of the bones having been dragged by beasts of prey into the small cavern at Kirkdale, that those of similar animals must have been introduced in all other cases in the same manner ; for, as all these animals were the antediluvian inhabitants of the countries in which the caves occur, it is possible that some may have retired into them to die ; others have fallen into the fissures by accident, and there perished ; and others have been washed in by the diluvial waters. By some one or more of these latter hypotheses, we may explain those cases in which the bones are few in number and not gnawed, the caverns large, and the fissures extending upwards to the surface ; but where they bear marks of having been lacerated by beasts of prey, and where the cavern is small, and the number of bones and teeth so great and so disproportionate to each other as in the cave at Kirkdale, the only adequate explanation is, that they were collected by the agency of wild beasts." In Germany the zoolithic caverns are much more numerous and important than in England. There is a remarkable example on the north-east border of the Hartz Mountains, called Bauman's Hohle, after an unfortunate miner who, in the year 1670, ventured into it alone in search of ore ; and, after having wandered three days and nights in its solitude and darkness, at length found his way out, but in such a state of exhaustion that he died almost immediately. It is a suite of natural chambers in a bed of transition limestone, the floor of which is composed of a thick crust of stalagmite, beneath which lies an accumulation of several feet of mud mixed with bones and pebbles. But the caves of Franconia are by far the richest and most beautiful of this class. They lie on the north-east extremity of the chain of the Juva between Nuremburg and Baireuth, in the valley of the Wiesent, a tributary stream of the valley of the Maine. The most important is the Cave of Gailen- reuth, situated in a perpendicular rock, its mouth being upwards of three hundred feet above the bed of the river, consisting of an aperture seven feet high and twelve broad. An open fissure in the rock ex tends from the cave to the table-land above, as shown in the illustration. The floor consists of stalagmite lying over a bed of slime which contains the animal remains. The cave has two chief cham bers, the roof of which is abundantly hung with stalactites. From the first to the second chamber the visitor descends by a ladder, as represented in the section, which exhibits the breccia of bones, pebbles, and loam, and the artificial ex tension of the cavern by the removal of it. Almost all the bones belong to the bear of the caverns, and are admirably preserved. Those of a species of cat, resembling the American jaguar, have also been discovered, and those of the hysena ; but the latter are of rare occurrence. In conformity with the habits of the bear, the remains of prey, dragged in, are almost entirely wanting. There^are two neighbouring caverns of the same class ; those of Zahnloch (teeth-hole) and Kiihloch. Gailenreuth. CAVERNS. 255 Section of Gailenreuth Cave. The latter is supposed to contain animal matter equal to at least 2500 individuals of the cavern bear ; and allowing an annual mortality of 2^, it follows that here we have the history of a thousand years ; for probably these animals retired to the solitude of this spot upon the approach of death, as is the well-known custom of many creatures. The bone caverns in our own country and the continent decisively prove that, pre vious to a great inundation in by-gone time, animals inha bited these districts, known not to have lived there, from the earliest K]!' records of human history — the rhinoceros, elephant, and hytena, now, and for ages past, exclusively confined to more southern latitudes. There is another class of caverns remarkable for the development of irrespirable gas, which often renders the access to them dangerous. They are of two kinds ; those in which the gas is produced by the surrounding rocks, and those in which it pro ceeds from the interior of the earth. The first class are principally caves of gypsum. The gypsum is not, however, the cause of the phenomenon, the component parts of which are not susceptible of any decomposition from the air. There is commonly foetid limestone intimately mixed up with it, which forms connected wavy stripes, and even single beds of considerable thickness. This earthy limestone, which is penetrated with bitumen, and often very clayey in its composition, has the property of giving out all its carburetted hydrogen in the air ; and in every case where caves exist in it, its presence, on account of its connection with gas, is offensive and much dreaded. In the limestone caves of the sandstone formations, on the contrary, there commonly prevails a very pure air, possibly because they are filled with mouldering animal remains. The development of irrespirable gases from the interior of the earth, which, penetrating through fissures, collect in caves, is a constant result of volcanic activity. The chemical processes continually going on in volcanic regions must produce the liberation of great quantities of gas, which are con nected with the world above by these chimneys of the perpetual forge. Caverns of this nature occur therefore only in the neighbourhood of volcanoes, or at points where volcanic processes may be supposed to be going on beneath. The gases so developed are almost entirely the carbonic and sulphuric acids. Among the most important of the grottos which give out carbonic acid, there is the Grotto del Cane at Naples, in the neigh bourhood of the Lago d'Agnano, near Pozzuoli. It was known to the ancients, and is mentioned by Pliny, who refers to it as one of a class of excavations called, in his time, " Charon's ditches." Its size is very unimportant ; ten feet deep, four feet broad, and nine feet high. The carbonic acid collects itself on the soil in a bed of about six inches deep ; and, on account of its specific gravity, does not mingle with the atmo spheric air. Its actual height may be clearly ascertained by lighting some candles, which, when they reach its surface, are extinguished at once. Small animals falling 256 1'IIYSICAL GEOGKAPIIY. in are speedily suffocated ; and it takes its name from the dogs which are placed in it by way of experiment. The cave and its neighbourhood appear to have undergone Grotto del Cane. some considerable changes ; for, from Pliny's reference to the mephitic gas, it would seem to have been fatal to human life, which is not possible now, owing to the small height of the stratum, unless an individual threw himself upon the surface of the floor. According to some ancient accounts, bubbles were constant upon the lake Agnano close by, occasioned by the escape of gas, of which there is no appearance now ; so that the quantity of deadly air exhaled has been much reduced, if dependence may be placed upon these authorities. A similar instance, on a much larger scale, is seen in the crater of the extinct volcano of St. Leger, or of Neyruc in the soutli of France, on the banks of the Ardeche, amid the great number of volcanic remains of that region. This crater exhibits a cultivated, and in part inhabited, district, which is surrounded like an amphi theatre by the ancient walls of volcanic debris. Its soil is one vast sieve for the ascent of carbonic acid. Perforations have been made in it to facilitate the emission of the gas, and guide it from the fields, to which its contact is very injurious. The height of the bed of gas, over the ground of these holes, has been found to be, in the most favourable circumstances, about one foot and a half. Changes of weather have the most important influence on it ; and in violent rains the whole mass of gas is absorbed. The quantity of this gas, which issues from the soil of the whole neighbourhood, has a very striking influence on the health of the inhabitants who work in these fields ; and if the proprietors do not yearly clear out these perforations, their harvest is lost by means of the poisonous vapours. Another example occurs near Pyrmont, where there is a cavern of mephitic gas, named Dunsthohle, which exhibits the same phenomena as the dog grotto near Naples ; and of a kindred kind is the extraordinary valley in the island of Java, called by the natives Guwo-upas, poisoned valley, which is without vegetation, and strewed with the skeletons of human beings, quadrupeds, and birds, being generally half-filled with a noxious gas which destroys life in a few minutes. In addition to the cavities which are the handiwork of nature, immense subterranean CAVERKS. 257 spaces have been excavated by the labour of man, chiefly in the limestone, coal, and salt formations, to obtain the products which are essential to the arts of life. At certain points and limits of the South Staffordshire " Coal Basin," the limestone stratification is abruptly exalted from its normal position, which is several hundred feet below the regular surface, and forms a striking object in scenery, and a picturesque mountain boundary, to the district of towns, hamlets, and villages, in which the usual mining operations for coal and iron stone are. pursued. It is worked to procure a valuable flux for the iron furnaces — cement for building — and a manure for agricultural purposes. Dudley Castle Hill is a bold and rugged prominence, where the quarries were primarily worked. The excava tions at first were open to the light, commencing from the protruding ridges and peaks, and forming in time a deep hollow or ravine. Clearing the rock as far as was convenient, the rapid inclination of the stratum was followed, and the work was then continued at a much lower level, in the form of gloomy tunnels, afterwards threaded by dark and dan gerous canals, necessary for the conveyance of the product of the perforated region. At the lower part of the castle grounds, and not far distant from the Eastern Lodge, is the descent to one of the great caverns, answering to our illustration. By a few uncertain slippery steps the visitor arrives at the moist crumbled floor of a wondrous avenue of rock works. Indistinctly, and at an inferior plane, glimmer the dull waters of the canal, the line of which is only broken in part by a covered way, to re-appear in the onward distance of the hazy mine. As the strata are sometimes at an angle of eighty degrees, some times less, the enormous broad-footed pillars of material left to support the irregular roof, answer to such inclination, and are perpendicular to it, presenting a wild and singular appearance. The force and sublimity of this scenery by torchlight are most interesting, and the frowning boundaries of the spacious crypts, the pillars, and the rude chambers, remind one distinctly of the mn/es of the Memphic tombs. Proceeding to the left, 25$ PHYSICAL GEOGRAPHY. and near to the porch of the cavern delineated, as also in progress towards the other extremity, yawning apertures aloft and laterally communicate with the celebrated ravine in the castle bounds, and receive a blue misty light into the gigantic casemate which illuminates the glistening and sparry walls, displaying the white frosted vapour upon the lips of the attendants and their guide. In sultry weather much danger is incurred by entering the caverns insufficiently protected from an altered temperature. The demand for the mineral treasures of the earth, and especially its coal, created by the advance of civilisation, has caused the undermining of its surface upon an extra ordinary scale in modern times, though some of our own mines date their origin from the era of the ancient Britons. This is the case, as the name imports, with Odin's mine, at the southern foot of Mara Tor in Derbyshire, a place deserving a visit. A shaft, nearly Entrance to Odin's Mine. a mile in length, leads to the vein of ore that is now worked, which varies in thickness from two or three inches to as many feet. Beautiful crystallisations of blende, barytes, calcareous spar, and selenite are found in this extensive excavation, as well as the curious and dangerous mineral called slikensides. " The effects of this extraordinary mineral," says Mr. Rhodes, " are not less singular than terrific. A blow with a hammer, a stroke or a scratch with a miner's pick, are sufficient to rend those rocks asunder with which it is united or embodied. The stroke is immediately succeeded by a crackling noise, which is sometimes accompanied with a sound not unlike the mingled hum of a swarm of bees ; shortly afterwards an explosion follows, so loud and appalling that even the miners, though a hardy race of men and little accustomed to fear, turn pale and tremble at the shock. This dangerous combination of matter must consequently be approached with caution. To avoid the use of the common implements of mining, a small hole is carefully bored, into which a little gunpowder is put and exploded with a match, which gives the workmen time to withdraw to a place of safety, there to await the result of their operations. Sometimes not less than five or six successive explosions ensue at intervals of from two to ten or fifteen minutes ; and occasionally they are so sublimely awful that the earth has been violently shaken to the surface by the concussion, even when the discharge has taken place at the depth of more than one hundred fathoms." SPRINGS. 259 CHAPTER V. SPRINGS. ATEK, essential to the existence of man and the fertility of the soil, occurs in each of the physical conditions which bodies are capable of assuming — the gaseous, solid, and liquid states. In the form of vapour, sustained in the atmosphere, it will be treated of in another section. In the solid condition, one of its aspects has been previously referred to — that of the glaciers of high mountain regions ; and in the lowland districts of the temperate zones, water annually as sumes a solid form, a mantle of snow lying upon the ground in winter, and a coating of ice upon the pools and rivers. Upon high elevations, also, even within the tropics^ these phenomena are perpetual ; arid, upon the level surface of circumpolar countries, snow and ice are constant features of the landscape. In a liquid state, the continental waters have the character of springs, rivers, or lakes, which vary greatly in their external appearance, and in the chemical composition of the fluid. The oceanic waters likewise display these characters ; for we may regard the broad expanse of dif ferent seas as vast lakes, while the numerous, strong, and permanent currents that occnr are the rivers of the deep ; and in various places it is certain that jets of fresh-water rise from the bottom of the ocean, which materially lessen its saltness in their neighbour hood. In the Gulf of Spezzia, a branch of the Gulf of Genoa — one of the finest har bours in the world, and of exquisite beauty — there is a powerful jet of fresh water rising in a liquid column from the bed of the sea ; and on the south coast of Cuba, at a consider able distance from the shore, there are fresh -water jets of such force, that boats cannot approach them without hazard. The general division of the waters of the globe is into salt, mineral, and fresh water. The ocean is the grand example of the former ; but there are many continental specimens of saline springs and lakes, which proceed from combina tion with rock-salt or sulphate of magnesia. The mineral waters arise from sulphur, arseniates, or other metallic substances, derived from the circumjacent earth, held in solu tion. For the most part, however, the continental waters are fresh, or somewhat similar to distilled water, whether resulting from rain, or the melting of snow and ice, and con stituting either springs, rivers, or lakes. Springs, whether gushing rapidly from rocky clefts, or gently oozing out of banks of earth, are interesting objects in the landscape, from the general purity of their waters, the frequent seclusion of their situations, their murmuring flow, and the green enamel of mosses and flowering plants to which the refreshing virtues of their streams give birth. There are not a few springs whose history may be traced back thousands of years, and which have acquired celebrity from their association with events and personages of a far remote antiquity. Who has not heard of the fountain of Arethusa, with its dark water, to which the hero of the Odyssey was directed by the goddess, upon returning to his native Ithaca? " Go, first the master of thy herds to find, At the Coracian rock, Where Arethusa's sable water glides." 2GO PHYSICAL GEOGRAPHY. This foun tain is about six miles in the interior of the island, the road as cending all the way. It is a small basin at the top of a ra vine, and is supplied by unceasing percolations through the superincum bent rock. Seated on a broken arch before it, the sides of the glen appear clothed with >tf7; leafy plants and odoriferous shrubs ; and onwards I1-1': through it a glimpse of the blue sea is caught, while the summit of the cliif above the fountain commands a view of the islands and mountains of Greece. Hither, it may be soberly believed, the author of the Odyssey, if not the hero, was a pilgrim, near three thousand years ago, |j and drank of the limpid spring at which now the goat herds of Ithaca quench their thirst. Dodwell, who visited this spot, describes its water as "clear and good, trickling gently from a small cave in the rock, which is covered with a smooth and downy moss. It has formed a pool four feet deep, against which a modern wall is built to check its overflowing. After oozing through an orifice in the wall, it falls into a wooden trough placed there for cattle. In the winter it overflows, and finds its way, in a thin stream, through the glen to the sea. The French had possession of Ithaca in 1798, and the rocks of the Arethusan fountain are covered with republican inscrip tions, 'Vive la Republique!' ' Liberte, egalite, et fraternite,' are seen scattered on all sides, but are becoming effaced." Who also has not heard of the fountain of Castalia, in which the Delphian Pythoness laved her limbs, and from which she, and the poets who versified her answers, were believed in part to derive their inspiration ? The poetical expression, the " dew of Castalie," refers to the spray of a cascade which descends through a cleft of Parnassus, fed by the snows upon its summit ; but the fount of inspiration, the bath used by the Pythia, is supposed to be a small shallow basin on the margin of the rill of the cascade, supplied with its own peren nial stream, which unites its superabundant water with that of the adjacent stream. Hero Ciistalian Spring on Mount 1'arnassus SPRINGS. 261 a striking change lias taken place within the period of authentic history. Where are the rich tributes of the Lydian king ? the spoils of Marathon and Salamis ? the sacred hall of the Amphictyonic council? the temple of Apollo? the city of Delphi, whose buildings are mentioned, in the records of its former magnificence, as covering two miles of ground ? There is not a vestige to be identified ; but Parnassus still exhibits its bold heights and transparent waters, unaffected by the passage of ages. " The shrine hath sunk ! but thou, unchang'd, art there ! Mount of the voice and vision, rob'd with dreams ! Unchang'd, and rushing through the radiant air, With thy dark waving pines, and flashing streams, And all thy founts of song ! Their bright course teems With inspiration yet ; and each dim haze, Or golden cloud, which floats around tliee, seems As with its mantle veiling from our gaze The mysteries of the past, the gods of elder days ! " The Castalian spring is now dedicated to St. John ; a pretty chapel bearing his name is by its side ; pendent ivy, moss, brambles, flowering shrubs, and a large fig-tree, throw a cool and refreshing gloom over the spot. Upon a buttress of the chapel, the inscription occurs, " Byron, 1806." But the poet has left another memorial of his visit. " Happier in this than mightiest bards have been, Whose fate to distant homes confin'd their lot, Shall I unmov'd behold the hallow'cl scene, Which others rave of, though they know it not? Though here no more Apollo haunts his grot, And thou, the Muses' seat, and now their grave, Some gentle spirit still pervades the spot, Sighs in the gale, keeps silence in the cave, And glides with glassy foot o'er yon melodious wave." Dr. Chandler speaks of the excessive coldness of the water of Castaly. " I began," lie states, " to wash my hands in it, but was instantly chilled, and seized with a tremor, which rendered me unable to stand or walk without support. This incident, when Apollo was dreaded, might have been embellished with a superstitious interpretation. Perhaps the Pythia, who bathed in this icy fluid, mistook lier shivering for the god." It is in the sandy deserts bordering on the tropics that springs acquire their highest importance and value, owing to the rarity of water, and the increased demand made for it by the heat of the climate. Here they are frequently connected with, verdant spots, similar to that of the interview between the Scottish Knight and the Emir in the brilliant tale of the " Talisman." " It Avas a scene," says Scott, " which, perhaps, would elsewhere have deserved little notice ; but as the single speck, in a boundless horizon, which pro mised the refreshment of shade and living water, — these blessings, held cheap where they are common, rendered the fountain and its neighbourhood a little paradise. Some generous or charitable hand, ere yet the evil days of Palestine began, had walled in and arched over the fountain, to preserve it from being absorbed in the earth, or choked by the flitting clouds of dust with which the least breath of wind covered the desert. The arch was now broken, and partly ruinous ; but it still so far projected over, and covered in the fountain, that it excluded the sun in a great measure from its waters, which, hardly touched by a straggling beam, while all around was blazing, lay in a steady repose, alike delightful to the eye and the imagination. Stealing from under the arch, they were first received into a marble basin, much defaced indeed, but still cheering the eye, by showing that the place was anciently considered as a station, that the hand of man had 262 PHYSICAL GEOGRAPHY. been there, and that man's accommodation had been in some measure attended to. The thirsty and weary traveller was reminded by these signs that others had suffered similar difficulties, reposed in the same spot, and, doubtless, found their way in safety to a more fertile country. Again ; the scarcely visible current which escaped from the basin, served to nourish the few trees which surrounded the fountain ; and where it sunk into the ground and disappeared, its refreshing presence was acknowledged by a carpet of velvet verdure." Some of the wells that occur in the wilderness of Arabia were halting-places to the descendants of Jacob in their migration through it, and appear under the same character now as then, shaded by a few palms, often supplying brackish and bitter water, capable of being sweetened by artificial means, and claimed as valuable property by the parties having territorial right to the soil. " And when they came to Marah, they could not drink of the waters, for they were bitter ; " but the juices of a plant thrown into them, rendered them palatable. There is every reason to suppose this spot to be the fountain Hawarah, a basin of unpleasant, saltish, and somewhat bitter water, near which Dr. Robinson found many bushes of the shrub Ghurkud in blossom, — a low thorny plant producing a red berry, which ripens in June, which is juicy and slightly acidulous, capable of correcting the bad qualities of the spring by mingling with it. " And they came to Elim, where were twelve wells of water, and threescore and ten palm trees." This is identified upon good grounds with Wady Gharandel, a valley about seven miles from the former station, a mile in breadth, with date trees, tamarisks, acacias of different species, and a copious fountain producing a small rivulet. The non-existence at present of twelve wells is no evidence, as Burckhardt remarks, against the conjecture, for water here is readily found by digging for it, and wells are frequently formed which the drifting sands fill up. Drawing water has ordinarily been the employment of females throughout the East, without distinction of rank, from a remote antiquity, — an onerous duty, as the wells are often at considerable distances from their habitations. " The daughters of the men of the city came out to draw water," is a remark which refers to a period separated by two thousand years from the time of a similar record, " there cometh a woman of Samaria to draw water." Equally ancient and general is the oriental practice of making the neighbourhood of a spring the scene of occasional festivity and mirth, a usage which was primarily a tribute of gratitude for its waters. " When I was at Ain, in Palestine," says Maritis, " a young Arab woman, at whose wedding I had been present on the first day of our arrival at the village, came hither to draw water. She was accompanied by some other women who were singing a song allusive to her marriage." We have a song of the Israelites, of the recitative kind, commemorating a spring, encountered soon after their emergence from the dry and thirsty desert. " Spring up, O well ! Answer ye to it ! " One party sung these words, and called upon another band to reply ; and they replied — " The well ! — The princes searched it out." And the chorus was, — " The nobles of the people have digged it, By decree ; upon their own borders." Dr. Clarke informs us that the Eleusinian women practised a dance about a well, that was called Callichorus ; the dance was also accompanied by songs in honour of Ceres ; and these songs of the well are still sung in parts of Greece and Syria. There is a similar practice in our own country, which will be adverted to upon a subsequent page. The origin of springs, a subject invested with considerable obscurity, has been referred to the rains and melted snow which the earth absorbs ; to the subterranean combination SPRINGS. 263 of the oxygen and hydrogen gases, which decompose each other, and produce water ; and to the filtering of water from the sea into internal cavities and reservoirs prepared by nature, from whence they make their way to the surface. Some writers contend for the former cause exclusively. Marriotte has examined the point, whether the quantity of rain water is sufficient to feed all the springs and rivers, and so far from finding a defi ciency, he concludes upon the amount being so great as to render it difficult to conceive how it is expended. According to experiments which have been made, there falls annually upon the surface of the earth about 19 inches of water, but to render his calculation still more convincing, Marriotte supposes only 15, which makes 45 cubic feet per square toise, and 238,050,000 cubic feet per square league of 2300 toises in each direction. Now the rivers and springs which feed the Seine, before it arrives at the Font-Royal at Paris, comprehend an extent of territory, about 60 leagues in length, and 50 in breadth, which makes 3000 leagues of superficial area ; by which, if 238,050,000 be multiplied, we have for the product 714,150,000,000, for the cubic feet of water which falls, at the lowest estimate, on the above extent of territory. Let us now examine the quantity of water annually furnished by the Seine. The river, above the Pont-Royal, when at its mean height, is 400 feet broad, and 5 deep. When the river is in this state, the velocity of the water is estimated at 100 feet per minute, taking a mean between the velocity at the surface, and that at the bottom. If the product of 400 feet in breadth, by 5 in depth, or 2000 square feet, be multiplied by 100 feet, we shall have 200,000 cubic feet for the quantity of water which passes in a minute through that section of the Seine above the Pont-Royal. The quantity in an hour will be 12,000,000 ; in a day 288,000,000 ; and in a year 105,120,000,000 cubic feet. This is not the seventh part of the water which, as previously stated, falls on the extent of country that supplies the Seine, the large remainder, not received by the river, being taken up by evaporation, besides a prodigious quantity employed for the nutrition of plants. A further calculation has been made by the same writer, of the water which ought to be furnished naturally by a spring that issues a little below the summit of Montmartre, and which is fed by an extent of ground 300 toises in length, and 100 in breadth ; making a surface of 30,000 square toises. At the rate of 18 inches for the annual quantity of rain, there will fall on that extent an amount equal to 1,620,000 cubic feet. A considerable part of this water, perhaps three-fourths, immediately runs off, so that no more than 405,000 forces its way through the earth and sandy soil, till it meets with a bed of clay at the depth of two or three feet, from which it flows to the mouth of the fountain, and feeds it. If 405,000 therefore be divided by 365, the quotient will be 1 100 cubic feet of water, which it ought to furnish daily, or about 38,500 French pints. This makes about twenty-seven pints per minute, which is nearly the produce of the spring. It appears from this and other calculations, that the rain which falls in particular districts is more than sufficient to account for all their springs and rivers ; and some very obvious circumstances show that the origin of springs is almost, if not entirely, owing to the rains which continually moisten the surface of the globe. In seasons of long drought, the greater part decrease in a considerable degree, and some absolutely fail, while they are renewed in the same progression as the descending showers are abundant. It is possibly the case, indeed, that the ocean filtering through pores of the earth — the salt particles being lost in the passage — may give rise to many springs ; but as the preceding cause is amply sufficient to explain their formation, we need not recur to any other. The rains and melted snow which the earth absorbs, percolate through crannies, or ooze through the strata, and collect in vast internal reservoirs in mountainous regions, from which the superabundant water finds its way again to the surface, breaking out through fissures in the side and at the bottom of the hills. Copious springs thus issue from the 264 PHYSICAL GEOGKAPIIY. mountain limestone of England, through the fissures of the rocks, produced in the course of the consolidation and shrinking of the mineral masses. They seldom appear, however, on the sides of limestone hills, but break out in great numbers, and often with extraordi nary impetuosity, around their bases. In other conditions of the surface, the water per colates through the masses of sand, gravel, or chalk, that compose it, till it meets the solid rock, or a bed of impervious clay, which arrests its further descent, and springs are then formed at the point of the lowest level, on the edge of the rock or clay that dams it up. With few exceptions, the lower beds of the chalk formation are completely saturated with water which has percolated through the superior strata to the base, where its downward course is stopped by a subsoil of blue clay, which occasions the accumulation in the lower regions of the chalk, and the springs and rivulets which issue near the foot of every chalk hill. It is more difficult to account for springs where the country is neither hilly nor uneven, but constitutes a great level or plain. The water in these instances reaches the surface by ascension, or flows in a direction contrary to that produced by the force of gravitation. There can be little doubt, however, that many of these springs derive their supply from distant elevations, and are produced by the natural tendency of liquids to find their level. Other examples are perhaps due to capillary attraction, in consequence of which water ascends through the pores of the earth in the same manner as it rises in capillary tubes — in sponge or sugar-loaf — so long as the hitter remains undissolved. In order to give a distinct though general view of the curious and complicated pheno mena of springs, they may be advantageously considered under different heads. 1. Perennial. Some springs are ever-ilowing, and answer to the expression of sacred poetry — the " fountains of living water." They do not dry up during the longest- continued drought, and suffer little or no diminution in their volume. These are obviously quite inde pendent of the last showers that have fallen, though their supply may primarily proceed from the rain and melted snow. It is rea sonable to suppose that they gush from a body of water collected in subterranean cavities, so vast as not to be drained off by the con stant stream during the most pro tracted season of dry weather, be fore the interior basin is reple nished. Of this nature is the celebrated spring of St. Winifred, at Holywell, in Flintshire, one of the finest in the world, which ap pears to be situate at the point where the limestone first comes in contact with the coal measures. The quantity of water thrown up is estimated at eighty-four hogsheads, or twenty-one tons, in a minute. It has never been known to fail, but is subject to reduction during drought. The stream never St. Winifred's Well. SPIUXGS. 265 freezes ; and though its course is little more than a mile before it arrives at the sea, yet eleven mills are put in motion by it. The spring issues from the rock into a beautiful polygonal well, over which the Stanley family erected a chapel about the time of Henry VII. Upon the windows the chief events of St. Winifred's life are painted. The saint is reported to have been a virgin martyr who suffered upon this spot, the spring miraculously rising from her blood; and hence the veneration for the well in popish times. Pennant says of his own time : " The custom of visiting this well in pilgrimage, and offering up devotions there, is not yet entirely set aside. In the summer a few are still to be seen in the water, in deep devotion, up to their chins for hours, sending up their prayers, or performing a number of evolutions round the polygonal well. In the year 1686 James II. visited this well, and received as a reward a present of the very shift in which his great grandmother, Mary Queen of Scots, lost her head." There are springs similarly powerful along the confines of the limestone district, which vary very little in their quantity of water, either in drought, or after the heaviest rains. About Denton, in Yorkshire, the roaring of the waters is incessant. 2. Intermittent. Many springs gush with vehemence, then subside, shrink away, and disappear, renewing their tide in its full strength at irregular intervals. They clearly derive their supply from the last rains, and hence fail altogether in dry seasons. On the chalk downs of the south of England, in Wilts and Dorset, it is a very common circum stance for the valleys to be quite dry in one part of the year, and very fully watered in another ; and hence a Wiltshire proverb says, " As the days lengthen, the springs strengthen." But we may suppose such a cavity in a hill as A in the diagram, a reservoir fed by rain percolating through the superior rocks, and communicating with the surface by an arched channel, like i; c D. As long as the water in the cavity is above the level of the channel at c, it will escape through it, and gush out at D ; but the spring will cease when the water of the interior basin has been reduced to that level, and not be re newed until it rises above it. The flow of the spring will also be more impetuous in proportion as the water of the cavity accumulates above the vertex of the siphon-formed arch. This is the prin ciple of the Artesian wells, which have been constructed with signal success near many large cities occupying level sitcS5 andj forraer]v inconv Jenc°ed by the want of natural springs, or by the bad quality of the surface water. The action of these wells, puits Artesiens — so named from the province of Artois, where they have been long in use — is due to the constant endeavour of liquids to find their level. If we suppose a basin-shaped country, or a plain enclosed with heights, the rain which falls on the circumjacent hills being absorbed among the rocks, may be conducted through one of the underlying strata of the plain, completely occupying it, and yet be prevented from sinking lower, and also from reach ing the surface, by inferior and superincumbent beds of solid rock or impervious clay. In such circumstances a perpendicular perforation or boring into the ground is made, penetrating the superior impervious bed, and reaching the saturated stratum through which the water rises to the surface. Thus suppose a town situated upon a bed of clay 266 PHYSICAL GEOGRAPHY. or mass of rock impervious to water, as A A ; B B a stratum through which it readily circulates, and which crops out or rises from beneath A A on each side ; c c also a rock through which it cannot pass. It is clear that rain, falling on the permeable stratum where it crops out, and being absorbed by it, yet prevented from passing downward under the action of gravity by the rock c C, will travel laterally through the stratum under the town, unable however to find its level, and force its way to the surface through the superincumbent rock A A. This is a condition in which an artificial boring at w, through A A to B B, will liberate the water of the latter, which will rise in the vent to the surface of the plain, in proportion as its source is elevated above it. Artesian wells, notwithstanding their modern name and its local derivation, appear to have been well known in various countries and in ancient times, without perhaps any apprehension of their principle. Neibuhr quotes an ancient writer as saying, " Wells are sunk in the oases from two to four hundred yards in depth (the yard in question being equal to half a foot), whence water rises and flows over." 3. Reciprocating. There are springs which exhibit phenomena analogous to the flux and reflux of the tides of the ocean, some at regular intervals during the day, and others at more distant and uncertain periods. In one of the two letters addressed by the younger Pliny to Licinius, he describes a spring of this kind by the Larian lake — the modern Lake of Como : — "I have brought you," he remarked, " as a present, out of the country, a query which well deserves the consideration of your extensive knowledge. There is a spring which rises in a neighbouring mountain, and, running among the rocks, is received into a little banqueting room, from whence, after the force of its current is a little restrained, it falls into the Larian lake. The nature of this spring is extremely surprising ; it ebbs and flows regularly three times a day. The increase and decrease is plainly visible and very amusing to observers. You sit down by the side of the fountain ; and whilst you are taking a repast, and drinking its water, which is extremely cool, you see it gradually rise and fall. If you place a ring or any thing else at the bottom when it is dry, the stream reaches it by degrees till it is entirely covered, and then gently retires ; and if you wait you may see it thus alternately advance and recede three succes sive times. Shall we say that some secret current of air stops and opens the fountain- head as it approaches to or retires from it, as we see in bottles, and other vessels of that nature, when there is not a free and open passage ; though you turn their necks down wards, yet, the outward air obstructing the vent, they discharge their contents as it were by starts ? But may it not be accounted for upon the same principle as the flux and reflux of the sea? Or as those rivers which discharge themselves into the sea, meeting with contrary winds and the swell of the ocean, are forced back into their channels, so may there not be something that checks this fountain, for a time, in its progress ? Or is there rather a certain reservoir that contains these waters in the bowels of the earth, which, while it is recruiting its discharges, the stream flows more slowly and in less quan tity ; but, when it has collected its due measure, it runs again in its usual strength and fulness ? Or, lastly, is there I know not what kind of subterraneous counterpoise, that throws up the water when the fountain is dry, and stops it when it is full ? You, who are so well qualified for the enquiry, will examine the reasons of this wonderful pheno menon : it will be sufficient for me, if I have given you a clear description of it. Fare well." The fact of the flow and ebb was reported, in antiquity, of a fountain, the celebrity of which is co-extensive with the prevalence of Christianity itself : — SPRINGb. " Siloa's brook that flow'd Fast bv the oracle of God." 267 Pool of Siloam. The pool of Siloam is a reservoir of artificial construction, fifty-three feet long by eighteen broad, into which a small stream flows, and is led off to irrigate the gardens of fig and fruit trees that lie along the slope of the Valley of Jehoshaphat. The stream enters the pool through a subterranean channel cut in the solid rock, and comes from the fountain of the Virgin, higher up in the valley. The irregular flow of the water is first distinctly mentioned by Jerome in one of his Commentaries, towards the close of the fourth century, who remarks: — " Siloam is a fountain at the foot of Mount Zion, whose waters do not flow regularly, but on certain days and hours, and issue with a great noise from hollows and caverns in the hardest rock." An earlier record in the same century — that of a still extant Itinerary from Bourdeaux to Jerusalem — magnifies this circumstance into a flowing for six days and nights, and a resting on the seventh day ; an ancient popular legend, which might originate the statement of the elder Pliny, of there being a river in Judea that dries up on the sabbath day. The popular belief is still firm among the inhabitants of Jerusalem, respecting the flow and ebb of the water ; but most modern travellers seem to have regarded it as an idle story, till Dr. Robinson was enabled to establish its truth. He has given the following account of the event: — "Having been, very unexpectedly, witnesses of the phenomenon in question, we are enabled to rescue another ancient historical fact from the long oblivion, or rather discredit, into which it has fallen for so many centuries. As we were preparing to measure the basin of the upper fountain (in the afternoon of April 30th), and explore the passage leading from it, my companion was standing on the lower step near the water, with one foot on the step and the other on a loose stone lying in the basin. All at once he perceived the water coming into his shoe ; and, supposing the stone had rolled, he withdrew his foot to the step, which, however, was also now covered with water. This instantly excited our curiosity ; and we now perceived the water rapidly bubbling up from under the lower step. In less than five minutes it had risen in the basin nearly or quite a foot ; and we could hear it gurgling off through the interior passage. In ten minutes more it had ceased to flow ; and the water in the basin was again reduced to its former level. Thrust ing my staff in under the lower step, whence the water appeared to come, I found that there was here a large hollow space ; but no further examination could be made without removing the steps. Meanwhile a woman of Kefr Selwan came to wash at the fountain. She was accustomed to frequent the place every day ; and from her we learned that the flowing of the water occurs at irregular intervals ; sometimes two or three times a day, and sometimes, in summer, once in two or three days. She said, she had seen the foun tain dry, and men and flocks, dependent upon it, gathered around and suffering from thirst ; when all at once the water would begin to boil up from under the steps, and (as she said) from the bottom in the interior part, and flow off in a copious stream. In order to account for this irregularity, the common people say " ' that a great dragon lies within 268 PHYSICAL GEOGKAl'IIY. the fountain : when lie is awake, he stops the water ; when he sleeps, it flows.'" The far- famed pool of Siloam is thus to be classed with the ebbing and flowing wells, though it does not appear that any character of periodicity belongs to the phenomenon. We have similar examples nearer home. In the diocese of Paderborn, in Westphalia, there is a spring which disappears twice in every twenty-four hours, returning always with considerable noise after six hours, and hence called by the inhabitants the bolder- born, or boisterous spring. Lay Well, near Torbay, also ebbs and flows very visibly, several times every hour, the distance between high and low-water mark, according to one observer, being somewhat less than half a foot. Another irregularly reciprocating spring occurs in the neighbourhood of Giggleswick, in Yorkshire, at the foot of the Scar, an almost perpendicular cliff of limestone and gravel, apparently about 150 feet high, and extending above three miles in length. The Avater discharged from the rock falls immediately into a stone trough, in the front of which are two holes near the bottom — the outlets of two streams that flow constantly from the artificial cistern. An oblong notch is also cut in the same side of the trough, which extends from the brim of it nearly to the level of the two holes already mentioned. This aperture is intended to show the fluctuations of the well : for the water subsides in the notch when the stream issuing from the rock becomes languid ; on the contrary, the surface of the water rises again in the notch, so soon as the influx into the trough begins to be more copious. The reciprocations of the spring are easily observed by this contrivance ; and they appear to be very irregular, both in respect of duration and magnitude. The interval of time betwixt any two suc ceeding flows is sometimes greater, and at other times less, than a similar interval which the observer may happen to take for his standard of comparison. The rise of the water in the cistern, during the time of the well's flowing, is also equally uncertain ; for it varies from one inch to nine or ten inches in the course of a few reciprocations. The spring discharges bubbles of air, more or less copiously, into the trough. These appear in the greatest abundance at the commencement of the flow, and cease during the ebb, or at least issue from the rock very sparingly at that time. The water is limpid, cold, and wholesome, and has no particular taste. Weeding Well, in the Peak of Derbyshire, other wise called the Ebbing and Flowing Well in the locality where it is situated, exhibits the same characteristic. It lies in a field by the road-side in the neighbourhood of Castleton Dale, surrounded with mud and weeds. The motion of the water depends upon the quantity of rain during the season, and is by no means regular, as it has ceased to flow for several weeks during a drought ; but, in very wet weather, it will flow and ebb more than once in an hour. The time which it continues to flow varies ; but it is sometimes four or five minutes, the water appearing at first slightly agitated, and then issuing forth from nine small apertures with a gurgling sound. After remaining stationary, it then ebbs to its ordinary level. The well is scarcely inclosed, and has the appearance of a pool; but the height to which it would rise would probably exceed a foot, if the margin were protected so as to prevent the overrunning of the water. It has been known to discharge twenty-three hogsheads in a minute. No theory has yet been proposed to account for the peculiarity of these springs which is perfectly satisfactory ; but probably the interposition of columns of gas conveying pressure, somewhat on the principle of Hero's fountain, acts an important part, as well as the common hypothesis of an interior cavity of water discharging itself by a siphon-formed channel 4. Thermal. Springs characterised by a higher temperature throughout the year than the mean of the latitude where they are situated, abound in active volcanic districts, as in the Neapolitan territories and Iceland, and are obviously referable to the action cf subterranean fire. They are frequent also in localities which have been the scenes of volcanic activity in past ages, as in Asia Minor, the neighbourhood of Rome, and Au- SPRINGS. 269 vergne. They are found, likewise, in countries far apart from both active and extinct volcanoes, and are probably due to a variety of causes — to the disengagement of subterra nean gases powerfully combined with caloric, to the decomposition of mineral substances, and to the internal heat of the globe. There are varieties of pyrites which are converted into sulphate of iron, by the contact of water, an evolution of heat accompanying the change ; and supposing a spring to flow through a bed of such pyrites, its waters might become thermal by such a decomposition. It is, however, a well-known fact that the internal temperature of the globe increases with the distance from the surface, and many of the warm springs may be simply occasioned by the superficial waters percolating through cracks and fissures to an immense depth, where they are variously heated by the high temperature of the interior, according to the extent of their penetration, and returned to the surface before being cooled down. Warm springs occur at Buxton, Stoney Middleton, and Matlock in Derbyshire, which, on account of their properties, and the beautiful localities in which they are situated, annually attract a number of visitors, and verify the remark of Seneca, " wherever warm springs abound, new places of amusement are sure to rise up." The heat of the Matlock water manges from 66° to 68° Fahrenheit ; that of Stoney Middleton, where it is believed the Romans established a bath, is 2° higher ; while that of the Buxton water is 82°, and never varies at any hour of the day, or season of the year. At the latter spot, some lines are still shown, as those which Mary Queen of Scots is said to have scratched upon one of the windows of the apartment she occupied : — Buxtona, qua; calida; cclebrabere nomine lymphzc, Forte mihi posthac non adeuncla, vale. " Buxton, farewell ! no more perhaps my feet Thy famous tepid streams shall ever greet." The south thermal waters of England, in the counties of Gloucester and Somerset, excepting Bristol, have a higher temperature than those of the north division, that of three of the springs of Bath being as follows : — Cross Bath 109°, King's Bath 114°, Hot Bath 117°. It appears somewhat remarkable that the tepid springs of Matlock rise from fifteen to thirty yards above the level of the river Derwent, while those that rise above and below that range are cold ; and the common occurrence of hot and cold springs, in close juxtaposition, seems not less anomalous. Homer, in describing the flight of Hector before Achilles, attributes to the Scamander, two fountain-heads, the one hot and the other cold : — " Next by Scainander's double source they bound, Where two fam'd fountains burst the parted ground ; This hot through scorching clefts is seen to rise, With exhalations streaming to the skies ; That the green banks in summer's heat o'erflows, Like crystal clear, and cold as winter snows." Homer is wrong in assigning such a source to this particular river, which bursts at once from a dark chasm in the Idrean mountains, amid scenery of the grandest description ; but the fact of hot and cold springs in the immediate vicinity of each other, blending their waters in one stream, is not an uncommon physical occurrence. The commander of the recent exploring expedition from the United States, Mr. Wilkes, witnessed a remarkable example of this in one of the islands of the Feejee group. On landing, the beach was found absolutely steaming, warm water oozing through the sands and gravel, in some places too hot to be borne by the feet. The springs were five in number, at some distance from the beach, occupying a basin forty feet in diameter. A small rivulet of 270 PHYSICAL GEOGRAPHY. fresh water passed close to the basin, so that one hand might be put into a scalding spring, and the other in water of the temperature of 75°. That of the spring was from 200° to 210°. The waters joined below, and the united streams stood at 145°, diminishing in temperature until they entered the sea. No gas appeared to be disengaged from the springs, in which the natives customarily boil their food, which is well done in about a quarter of an hour. Strange as it appears to find hot and cold streams pouring from the bosom of the earth within a few paces of each other, their subterranean courses may be far apart, and be prosecuted under widely different circumstances, the one percolating through substances which occasion the evolution of heat, or rising up from an immense depth where it has been heated by interior fires, and the other confined entirely to the superficial strata. When the Romans came into Gaul, they found a warm spring in Provence, which furnished an abundant supply of water, and which received the name of Aquce Sextice, from Sextus Calvinus, who established baths, and laid the foundation of the modern city of Aix upon the spot. Through digging in the neighbourhood, about a thousand paces distant, some cold springs were laid open, and the spring of Sextus gra dually diminished, and became perfectly dry. In 1721, the plague then raging at Aix, the physicians declared that the warm spring would be highly beneficial for bathing, and the other springs were accordingly stopped, and in twenty-two days that of Sextus re appeared. It seems evident, therefore, that their waters are identical, cold and hot within the superficial distance of a thousand paces, but their passage from the one point to the other is no doubt that of a descent to a great depth, where the warm temperature is acquired, from whence they remount to the surface. Thermal springs are common in the Alps and Pyrenees, and in the districts lying around their roots, particularly in the Grand Duchy of Baden, where they have occa sionally a very high temperature. The town of Baden was the Civitas Aurelia Aquensis of the Romans, and possesses thirteen warm springs, the principal of which, called the Ursprung, produces 7,500,000 cubic inches of water in twenty-four hours, with a tem perature of 153-^°. The temperature of the thermal springs on the northern side of the Alps is — Leuk, twelve springs, varying from 117° to 126°; Naters, 86° ; St. Gervaise, 94° to 98° ; Aix les Bains, 114° to 117° ; Moutiers, 101° ; and Brida, 97°. These springs rise near the bottom of the great calcareous formation that covers the northern side of the Alps, and near its junction with the mica slate that covers the granite. Mr. Bake- well refers the temperature of the thermal waters of the Alps and Pyrenees to interior combustion, to the agency of which, the original elevation of the mountains may be due ; and the conclusion is supported by the fact, that the districts where the hot springs are situated, have been subject to great and frequent convulsions, particularly the Haut Vallais, where the temperature of the water is the highest. In the year 1755, at Brieg, Naters, and Leuk, the earth was agitated with earthquakes every day for four months, and some of the shocks were so violent, that the steeples of churches were thrown down, the walls were split, many houses became uninhabitable, and the waters of the Rhone were observed to boil. It is probably true of most hot springs, that they owe their temperature to subterranean fire, as much as those in the neighbourhood of Vesuvius, though occurring in countries where no indications of igneous action are exhibited by the superficial crust of the earth. It is corroborative of this statement, that during the great earthquake that destroyed Lisbon in 1755, the hot springs at Moutiers, in Savoy, ceased to flow for forty- eight hours, and increased in quantity when they flowed again ; and similar springs at Toeplitz, in Bohemia, became turbid, then ceased, and subsequently discharged an increased volume of water. At the same time, the temperature of the Source de la Reine, at Bagneres de Luchon, in the Pyrenees, was raised 75° ; and the hot springs at Bristol were discoloured. SPRINGS. 271 The temperature of springs, hot, tepid, and cold, is remarkably uniform, under ordinary circumstances, as measured by the thermometer immersed in the water. But it may apparently vary diurnally in tropical countries, like that of rivers and lakes, as estimated by the immersion of the hand — a fact which the ancients converted in one instance into a marvel Thus wrote Lucretius : — " A fount, 'tis rumour'd, near the temple purls Of Jove Ammonian, tepid through the night, And cold at noon-day ; and th' astonish'd sage Stares at the fact, and deems the punctual sun Strikes through the world's vast centre, as the shades Of midnight shroud us, and with gay reverse Madden the well-spring : creed absurd and false. Pliny refers to this fountain, with some exaggeration, as cold in the daytime, and scorching hot at night ; and Ovid likewise : — " Thy stream, 0 horn-crown'd Ammon ! in the midst Chills us at noon, but warms at morn and eve." The reported prodigy is a very common-place occurrence, entirely caused by the strongly contrasted temperature of the air in the Libyan desert, which renders the waters still flowing around the ruined temple of Ammon cooler to the senses by day than by night. 5. Ebullient. — Springs displaying violent ebullition, sending off vast clouds of steam, and throwing up their scalding water to a considerable height in the form of a jet, are the common phenomena of volcanic regions. In the island of St. Michael, one of the Azores, there is a round, deep, and lovely valley, its sides covered with myrtles, laurels, and mountain grapes, with wheat, Indian corn, and poplars waving upon its fields, in which many boiling fountains occur. The principal, called the Caldeira, is on a gentle eminence by the side of a river, and boils with great fury, and the river itself exhibits ebullition in various places, where the water is too hot to be borne by the hand. But the most re markable of these springs are found in Iceland, and constitute, owing to their diversified appearances, sublime, beautiful, and terrible objects in that strange region, where the extremes of heat and cold, in the form of ice and fire, are in near proximity. They are found in vai'ious parts of the island, but the chief are situated in its south-western division, on a plain at the base of a low range of hills, about thirty-six miles from Hecla. Here, within a circle of two miles, above a hundred are contained, some of which boil incessantly, without any discharge of their contents, while others cast their waters high into the air. To the principal of these springs the name of Geyser is applied — a term derived from the Icelandic geysa, signifying to burst forth with vehemence and impetuosity. There are two, more remarkable than the rest, called the Great Geyser and the New Geyser, whose columns of vapour are seen by the traveller long before he reaches their site. " At the distance of several miles," says Henderson, " on turning round the foot of a high moun tain on our left, we could descry, from the clouds of vapour that were rising and convolv ing in the atmosphere, the spot where one of the most magnificent and unparalleled scenes in nature is displayed." The Geysers are intermittent hot springs ; and on approaching the Great Geyser, when in a quiet state, it presents the appearance of a large circular mound, formed by the depositions of the fountain. Ascending the mound, a spacious basin is seen, partly filled with hot water, clear as crystal, and gently bubbling. In the centre there is a cylindrical pipe or funnel, about eighty feet in depth, and from eight to ten feet in diameter, widening at the top, and opening gradually into the basin. The inside exhibits a whitish surface, consisting of a siliceous incrustation, which has been rendered smooth by the action of the boiling water. The basin is about 1 50 feet round ; and, when full, the water it contains is about four feet deep, measuring from the surface 272 PHYSICAL GEOGRAPHY. to the commencement of the pipe. The water, occasionally running over the edges of the mound, has acted upon the surrounding peat, mosses, and grass, incrusting them with stone, and furnishing fine specimens of petrifaction. Such is the Geyser when asleep ! The whole scene changes when it is in action, which occurs at irregular intervals. Explosions in the bowels of the earth, like reports of cannon, shake the ground, and warn the visitor to retire to a distance, for they announce an eruption. The water in the basin becomes more and more agitated ; it boils furiously ; and at last it is suddenly projected into the air, in a succession of jets, which are at first inconsiderable, but become more powerful, till a magnificent, column is sent up to a great height, finishing the display, as though the Geyser, like a thing of life, summoned all her power to dignify her retreat. This is the grandest part of the exhibition. The atmo sphere is filled with immense volumes of steam, rolling over each other as they ascend, through which the columns of water, shivering into foam and spray, are seen spreading in all directions. As the jets rise out of the basin, the water reflects the most beautiful colours — sometimes a pure and brilliant blue, or a bright sea green ; but, in its farther ascent, all distinctness of colour is lost ; and the tops of the jets, receiving the rays of the sun, are white as snow. It appears, from the observations of various visitors, that the height of the jets is very irregular, and the power of the Geyser very unequal. In Olaf- sen and Poveisen's time, the water was carried to the height of three hundred and sixty feet! When seen by Von Troil, in 1772, it rose to ninety -two feet. Sir John Stanley states the highest jet observed by his company, in 1789, to have been ninety-six feet. Lieutenant Ohlsen, a Danish officer, in 1804, found by a quadrant that the highest jet rose to two hundred and twelve feet. In 1809 Mr. Hooker mentions its rising to upwards of a hundred feet ; and Sir George Mackenzie states ninety feet to have been the height to which he saw the water thrown in 1810. The New Geyser is somewhat different in its external structure from the preceding fountain, but its eruptions are marked with the same characteristic features. The name of Stockr is applied to it by the Icelanders, signifying, to agitate — originally the name of a fountain close by, which, immediately after an earthquake in 1789, became entirely tranquil, when New Stockr began to erupt. Henderson witnessed the joint eruption of both Geysers, of which he gives the following description : — " About ten minutes past five in the morning we were aroused by the roaring of Stockr, which blew up a great quantity of steam ; and when my watch stood at the full quarter, a crash took place as if the earth had burst, which was instantaneously succeeded by jets of water and spray, rising in a perpendicular column to the height of sixty feet. As the sun happened to be behind a cloud, we had no expectation of witnessing any thing more sublime than we had already seen. But Stockr had not been in action above twenty minutes, when the Great Geyser, apparently jealous of her reputation, and indignant at our bestowing so much of our time and applause on her rival, began to thunder tremendously, and emitted such quantities of water and steam, that we could not be satisfied with a distant view, but hastened to the mound with as much curiosity as if it had been the first eruption we had beheld. However, if she was more interesting in point of magnitude, she gave the less satisfaction in point of duration, having again become tranquil in the course of five minutes ; whereas her less gaudy but more steady companion continued to play till within four minutes of six o'clock." Henderson mentions the singular fact, that by throwing a great quantity of large stones into the pipe of Stockr, he could awaken the slumbering giant, and bring on an eruption in a few minutes. It has been thought a remarkable cir cumstance, that the old Icelandic annals should be entirely silent respecting these marvels of the island. An apparent allusion to them occurs in the ancient poem, the Voluspa, in the Edda : — SPRINGS. 273 '• At the end of time The vapours rage (geysar), And playful flames Involve the skies." Ari Frode, the first historiographer of the north, who flourished in the eleventh century, was educated within a mile of the Geysers, yet makes no mention of them ; nor are they referred to by a native Icelander, till the time of Svenson, bishop of Skalpolt, in the seventeenth century. But no argument can be founded upon this fact, to prove that The Great Geyser. the boiling fountains were not in full play when the first Norwegian colonists took pos session of the soil, in the ninth century, more than that Herculaneum and Pompeii were not overwhelmed by the eruption of Vesuvius in the year 79, because Pliny, who saw the volcano explode, who lost his uncle by it, and minutely describes the event, omits all notice of the buried cities — one of the most unaccountable circumstances in the range of history. The explanation of these great efforts of nature, given by Sir C. Lyell, is simple and ingenious, founded upon the general supposition of a subterranean cavity where water and steam collect, and where the free escape of the steam is prevented till it acquires sufficient force to discharge the water. He supposes water from the surface of the earth to penetrate into the cavity A D by the fissures F F ; while at the same time steam, at an extremely high temperature, rises up wards through the fissures c C. When the steam reaches the cavity, a portion of it is at first con densed into water; and it gradually raises the temperature of the water already there, till at last the lower part of the cavity is filled with boiling water, and the upper part with steam under high pressure. As the pressure of the steam increases, its expansive force becomes greater ; and at length it forces the 274 PHYSICAL GEOGRAPHY. boiling water up the fissure or pipe E B, and a considerable quantity runs over the rim of the basin. When the pressure on the steam in the upper part of the cavity is thus diminished, it expands till all the water, D, is driven to E, the bottom of the pipe ; and when this happens, the steam rushes up with great velocity, as on the opening of the valve of a steam-boiler. Sir C. Lyell, upon the same principle, accounts for the eruption of volcanoes, referring it to the agency of steam upon melted lava accumulated in cavi ties in the bowels of the earth — a theory which, though not demonstrable, is invested with a high degree of probability. Incidental notice may here be taken of some springs which appear to boil, but are cold to the touch and to the thermometer. They are occa sioned by currents of pure air or gases being in connection with their waters. There is one of this kind at Peroul, near Montpellier, which bubbles and heaves up furiously ; and some parts of the river Etang, in the vicinity, exhibit the same appearance. Dr. Robin son found, in several dry places of the ground in that district, many small passages or clefts, at the mouth of which he placed light bodies, such as feathers, straws, and leaves, which were speedily blown aside. A remarkable spot was visited by Humboldt in South America, where phenomena of a class similar to those of the ebullient springs appeared — the eruption of water, mud, and air from the surface. The scene of this exhibition was near the Indian village of Tur- baco, in the neighbourhood of Carthagena — a beautiful district adorned with luxuriant vegetation. After pushing his way through thickets of palm-trees, he reached an open space almost entirely devoid of verdure, called, by the natives, Los Volcanitos. They affirmed that, according to a tradition preserved in the village, the ground had formerly been ignited ; but that a monk had extinguished it by frequent applications of holy water, and converted the fire volcano into a water volcano. The volcanitos consisted of several small truncated cones, having a height of about twenty feet, and their circumference at the base near eighty yards. At the top of each cone there was an aperture, about two feet in diameter, filled with water, through which air-bubbles obtained a passage. Each of the bubbles contained upwards of a cubic foot of elastic fluid; and their power of expansion was often so great, that the water was projected over the brim of the cone. Some openings by which air escaped were observed in the plain, without being sur rounded by any prominence of the ground. The natives asserted that there had been no observable change in the form and number of the cones for twenty years, and that the little cavities are filled with water even in the driest seasons. The temperature of the water and mud was not higher than that of the atmosphere ; the latter having been 81-5°, and the former 80-6° or 81°, at the time of Humboldt's visit. A stick could easily be pushed into the apertures to the depth of six or seven feet ; and the dark-coloured clay or mud was exceedingly soft. An ignited body was immediately extinguished on being immersed in the gas collected from the bubbles, which was found to be pure azote. Here, botanising in the magnificent woods around, the traveller spent several happy days with Bonpland — the scientific companion of his journey, afterwards seized by the tyrant Francia — the subject of the following pleasing allusion, written in 1831 : "At Turbaco we lived a simple and laborious life. We were young ; possessed a similarity of taste and disposition ; looked forward to the future with hope ; were on the eve of a journey which was to lead us to the highest summits of the Andes, and bring us to volcanoes in action in a country continually agitated by earthquakes ; and we felt ourselves more happy than at any other period of our distant expedition. The years which have since passed, not all exempt from griefs and pains, have added to the charms of these impressions ; and I love to think that, in the midst of his exile in the southern hemisphere, in the solitudes of Paraguay, my unfortunate friend, M. Bonpland, sometimes remembers with delight our botanical excursions at Turbaco — the little spring of Torecillo — the first sight of SPRINGS. 275 a Gustavia in flower — or of the Cavanillesia loaded with fruits, having membranous and transparent edges." 6. Inflammable. Springs capable of firing and supporting flame are found in several parts of the globe, and, though not very numerous, they have been known from a very early era. They arise from combination with combustible substances of hydrogen gas. The substance usually found oozing out of the earth, in connexion with their waters, passes under the various names of pitch, naphtha, petroleum or rock oil, and bitumen. Naphtha is the purest state of this substance, which becomes petroleum upon a certain exposure to the air, and bitumen upon a continued exposure to it. The fountain by the temple of Jupiter, at Dodona, was inflammable, according to the account given of it by the Roman natural philosopher and poet Lucretius : — " A fount there is, too, which, though cold itself, With instant flare the casual flax inflames Thrown o'er its surface ; and the buoyant torch Kindles alike immediate, o'er its pool Steering the course th' etherial breeze propels." Pliny confirms this representation ; and if, with Colonel Leake, we suppose Dodona to have been in the valley south of the lake of loannina, in Epirus, the statement may be true ; for now, in Ulyria and Zante, at no great distance, there are pitch springs ; and, in the latter, they were certainly in existence 2300 years ago, as we learn from Herodotus. " In Zacynthus," says the historian, " I saw pitch brought up out of the water of a pond. Indeed there are several of these ponds ; but the largest of them is about seventy feet square, and twelve feet deep. The mode of procuring the pitch is the following : — They take a pole, and push it into the water with a myrtle branch at the end ; and, on pulling it up, they find the pitch adhering to it, which in smell is like asphaltus, but of a better quality than the common pine pitch. They collect this pitch in a kind of vat or recep tacle which they have dug near the pond ; and, when the quantity is considerable, they put it in large jars or barrels." The historian might be describing an operation of the present day, so exactly do the proceedings of the modern Zanteotes correspond with his account. The great region of naphtha springs is to the west of the Caspian, in the terri tory of Baku, where a scene presents itself alike marvellous and unique. The naphtha streams spontaneously through the surface, and rises wherever a hole is bored. Speak ing of a spot where it most abounds, Colonel Rottiers states: — "It appears to undergo distillation as it ascends to the surface, and thence falls down the sides of the mountains into reservoirs, constructed at some unknown period. It is conjectured, that entire forests of resinous trees were once engulfed by some violent effort of nature, and that their decomposition is the origin of this inflammable liquid. The colour of the oil is black ; but it shines with a reddish tint when the sun's rays are upon it." Not far from the same spot he observed a current of white oil gushing out, which readily inflames and burns upon the surface of water ; and in calm weather the people of the country amuse them selves by pouring whole tons of it into a bay of the Caspian. They then set fire to it ; and it is borne out of sight, giving the waves the appearance of a sea of fire ; and, in com parison with this splendid exhibition, our finest illuminations and fireworks sink into insignificance. Petroleum springs occur in the territory of Modena and Parma, in Sicily, and in the Birman empire, where, in one locality, there are said to be upwards of five hundred wells, yielding annually 400,000 hogsheads. Around the island of Trinidad, also, fluid bitumen oozes from the bottom of the sea, and rises to the surface of the water ; while, in the interior of the island, there is a vast collection of bituminous matter, forming a great pitch-lake, with frequent crevices and chasms filled with water. The origin of the substance in this locality is referred by some writers to the immense quan- 276 PHYSICAL GEOGRAPHY. titles of woody and vegetable bodies brought down in the course of ages by the river Orinoco, which, becoming arrested in particular places by the influence of currents and eddies, and subject to the agency of subterranean fire in this region of volcanic action, have undergone those transformations and chemical changes which produce petroleum, converted into pitch upon being forced up to the surface and exposed to the air. There are waters, however, unconnected with bitumen, from whose surfaces flames dart out, without the liquid being at all hot. These contain inflammable gases, disengaged from masses of iron, zinc, and tin, dissolved by sulphuric and muriatic acids. Such are the fountains of Poretta Nuova, and a brook near Bergerac, which may be kindled by a lighted straw. Similar springs have appeared near Wigan in Lancashire, and Brosely in Salop, by the banks of the Severn. 7. Mineralised. Water is seldom found in a pure state, that is, without colour, taste, or odour. It is generally met with possessing these properties ; and even when its odour is not cognizable by man, the keener sense of the camel will scent it afar off in the desert. Rain water is impregnated with whatever foreign ingredients may exist in the atmosphere through which it descends ; and spring water, besides betraying the ingredients usually found in the rains from which it proceeds, becomes charged with a variety of substances and gases in percolating through the superficial strata of the earth. When these are present in an extraordinary degree, so as to produce some sensible effect upon the animal economy, the springs so constituted are termed mineral, and are both cold and thermal. The mineral waters may be grouped generally into the four following classes, and occur at the places annexed to them : — Saline Aperient Waters. — In Germany, at Carlsbad, Marienbad, Egra, Kissengen, Wiesbaden, Baden-Baden, Seidlitz, and Pullna. In England, at Cheltenham, Lea mington, Harrowgate, Northwich, Epsom, and Ashby-de-la-Zouch. In Scotland, at Dumblane and Pitcaithly. Alkaline Waters. — In Germany, at Carlsbad, Marienbad, Kissengen, Pullna, Saidschutz, Ems, Toplitz, and Wiesbaden. In England, at Harrowgate, Scarborough, Cheltenham, Leamington, and Bath. In France, at Vichy and Mont d'Or. Chalybeate and Acidulous Waters. — In Germany, at Spa, Pyrmont, Schwalbach, Marienbad, Aix-la-Chapelle, and Seltzer. In England, at Tollbridge, Harrowgate, and Brighton. In Scotland, at Peterhead. Sulphureous Waters. — In Germany, at Aix-la-Chapelle. In the Pyrenees, at Bareges. In England, at Harrowgate, Askern, and Kedleston. In Scotland, at Moffat and Strathpeffer. The foreign sulphureous springs mentioned are hot; the domestic, cold. The waters of many of the chalybeate springs frequently hold in solution so large a quantity of iron, as to encase with a ferruginous deposit the channels through which they pass, depriving of their natural green the mosses and grasses which are laved by the stream, and covering them with a yellow incrustation. The brine springs of Northwich, which rise up through beds of rock-salt, are also so fully saturated, as to yield an annual supply of upwards of forty thousand tons of salt manufactured from them, besides the large quantity taken from the mines. But of all mineral ingredients, lime combined with carbonic acid occurs in the greatest abundance in springs, some of which are thermal. The deposition of the calcareous matter held in solution takes place when the acid is dissipated in the atmosphere, and extensive formations are produced. So rapid is the precipitation of carbonate of lime at the hot baths of St. Vignone, in Tuscany, that half a foot of solid travertine is the annual product near their source. The hot waters of Hiera- polis have been similarly productive. This city, now a site of desolate ruins, was formerly one of the most flourishing in Asia Minor, and was resorted to for its thermal SPRINGS. 277 springs, celebrated in a still extant inscription : — " Hail golden city Hierapolis ! the spot to be preferred before any in wide Asia, revered for the rills of the nymphs, adorned with splendour !" The ancients speak of the transforming power of the waters, and relate that being conducted about the vineyards and gardens, the channels became long fences, each a single stone. There is now a powerful hot spring feeding numerous rills, and a calca reous cliff, an entire deposition from it. The occurrence of petrifactions, which puzzled science a century ago, and which rustic ignorance accepted as instances of the real trans mutation of different objects into stones, is now well known to arise from the deposition upon them of the earthy ingredients of the waters to which they are exposed, investing them with a calcareous or siliceous crust. The Dripping Well at Knaresborough, on the banks of the Nidd, often visit ed on account of its inviting scenery, and the cave of Eugene Aram in the neigh bourhood, is a curious petrify ing spring ; and at the Mat- lock Wells the process of pe- trification is shown, objects which are put into them be coming soon encrusted with the limestone precipitated from the water as it evaporates. A considerable number of springs have recently been found to contain iodine or bromine. Those which issue from the lias at Leamington, Gloucester, Tewkesbury, and Cheltenham, contain iodine. The saline aperient waters of Epsom con tain a small quantity of bro mine, which is also found in the springs from the coal for mation of Asliby-de-la-Zouch, Newcastle, and Kingswood. In several European springs, a remarkable animal substance has been detected, termed glairine, which may be derived from strata containing animal fossil remains, through which the water percolates. Such are the chief peculiarities of the subject of this chapter. No apology need be offered for devoting so much space to it ; for, however incompetent to explain all the phe nomena, there can be no difference of opinion as to the high interest and practical utility of the phenomena themselves. The springs are the sources of the rivers which fertilise the soil through which they flow, and form the navigable channels which offer nations a convenient medium of intercommunication. To the geologist, they speak in the language of comment respecting the interior constitution of the globe, by their occasional high temperature and mineral composition, and the mode in which many of its strata have been produced, by the solid products in course of formation from their waters. The medicinal virtue of their streams is also a beneficial item of no mean importance ; and whether welling through the loose sand and stony pavement of the Arabian desert, or breaking Dripping Well, Knaresborough. 278 PHYSICAL GEOGRAPHY. forth at the grassy foot of a grove-crowned hill, the fountains of the earth are inviting objects of contemplation, through their association with the ideas of purity and bene volence, independently of being beautiful parts of natural scenery. Hence we may sympathise with the sentiment that inspired the ancient song of the "Well, and regard as an appropriate homage, when under due restraints, that principle of veneration for the waters which pervaded the mind of all antiquity, and has survived in some rural customs to the present day. Milton, in his Comus, alludes to the honours formerly paid to the Severn : " The shepherds at their festivals Carol her good deeds loud in rustic lays, And throw sweet garland wreaths into her stream, Of pansies, pinks, and gaudy daffodils." There is an elegant custom still observed by the villagers of Tissington, in Derby shire, of a similar kind — that of dressing their wells with flowers on Ascension day. There are five copious springs issuing out of the limestone, which are decorated with boughs of laurel and white thorn, interspersed with the flowers of the season, arranged in various patterns and inscriptions. The effect is singularly beautiful ; and the procession of the peasantry to sing at each well — a graceful usage handed down from a remote age — forms a very agreeable spectacle. CHAPTER VL RIVERS. JVER3 constitute an important part of the aqueous portion of the globe. With their tributaries, the small streams and rivulets, they form a numerous family, of which lakes, springs, or the meltings of ice and snow, upon the summits of high mountain chains, are the parents. The Shannon has its source in a lake ; the Rhone in a glacier ; and the Abyssinian branch of the Nile in a confluence of fountains. The country where some of the mightiest rivers of the globe have their rise, has not yet been sufficiently explored to render their true source ascertainable. The origin of others is doubtful, owing to a num ber of rills presenting equal claims to be con sidered as the river-head ; but many are clearly referable to a single spring, the current of which is speedily swelled by tributary waters, ultimately flowing in broad and deep channels to the sea. Inglis, who wandered on foot through many lands, had a fancy, which he generally indulged, to visit the sources of fivers, when the chances of his journeys threw him in their vicinity. Such a pilgrimage will often repay the traveller by the scenes of picturesque and secluded beauty into which it leads him ; and even when the primal fount is insignificant in itself, and the surrounding landscape exhibits the tamest features, there is a reward in the associations that are instantly wakened up — RIVERS. 281 The Susquehanna. inequalities, but many are formed by the arrest and gradual accretion of the alluvial matter brought down by the waters. There is great diversity in the length of rivers, the force of their current, and the mass and complexion of their waters ; but their peculiar character is obviously dependent upon that of the country in which they are situated. As it is the property of water to follow a descent, and the greatest descent that occurs in its way, the course of a river points out generally the direction in which the land declines, and the degree of the declination determines in part the velocity of its current, for the rapidity of a stream is influenced both by its volume of water and the declivity of its channel. Hence one river often pours its tide into another without causing any perceptible enlargement of its bed, the additional waters being disposed of by the creation of a more rapid current, for large masses of water travel with a swift and powerful impetus over nearly a level surface, upon which smaller rivers would have only a languid flow. In general, the fall of the great streams is much less than what would be supposed from a glance at their currents. The rapid Rhine has only a descent of four feet in a mile between Schaffhausen and Strasburg, and of two feet between the latter place and Schenckenschautz ; and the mighty Amazon, whose collision with the tide of the Atlantic is of the most tremendous description, falls but four yards in the last 700 miles of its course, or one-fourth of an inch, in 1 J miles. In one part of its channel the Seine descends one foot in a mile ; the Loire between Pouilly and Briare one foot in 7500, and between Briare and Orleans one foot in 13,596; the Ganges, only nine inches ; and, for 400 miles from its termination, the Paraguay has but a descent of one thirty-third of an inch in the whole distance. The fall of rivers is very unequally distributed ; such, for instance, as the difference of the Rhine below Cologne and above Strasburg. The greatest fall is com monly experienced at their commencement, though there are some striking exceptions to this. The whole descent of the Shannon from its source in Lough Allen to the sea, a dis tance of 23-4 miles, is 146 feet, which is seven inches and a fraction in a mile, but it falls 97 feet in a distance of 15 miles between Killaloe and Limerick, and occupies the remaining 219 miles in descending 49 feet. When water has once received an impulse by following a descent, the simple pressure of the particles upon each other is sufficient to keep it iu 282 PHYSICAL GEOGRAPHY. motion long after its bed has lost all inclination. The chief effect of the absence of a declivity is a slower movement of the stream, and a more winding course, owing to the aqueous particles being more susceptible of divergence from their original direction by „.-'•-'." _,, impediments in their path. Hence the tortuous character of the water-courses, chiefly arising from the streams meeting with levels after The Rhine at Obcrweisel. descending inclined planes, which so slackens their speed that they are easily diverted from a ri^ht-onward direction by natural obstacles, to which the force of their current is inferior. The Mseander was famed in classical antiquity for its mazy course, descending from the pastures of Phrygia, with many involutions, into the vine-clad province of the Carians, which it divided from Lydia near a plain properly called the Maeandrian, where the bed was winding in a remarkable degree. From the name of this river we have our word meandering, as applied to erratic streams. This circumstance increases prodigiously the extent of their channels, and renders their navigation tedious, but the absence of that velocity of the current which would make it difficult is a compensation, while a larger portion of the earth enjoys the benefit of their waters. The sources of the Mississippi are only 1250 miles from its mouth, follow ing a straight line, but 3200 miles, pursuing its real path ; and the Forth is actually three times the length of a straight line drawn from its rise to its termination. The rivers which flow through flat alluvial plains frequently exhibit great sinuosities, their waters returning nearly to the same point, after an extensive tour. The Moselle, after a curved course of seventeen miles, returns to within a few hundred yards of the same spot ; and a steamer on the Mississippi, after a sail of twenty-five or thirty miles, is brought round again, almost within hail of the place where it was two or three hours before. In high floods, the waters frequently force a passage through the isthmuses which are thus formed, converting the peninsulas into islands, and forming a nearer route for the navigator to pursue. By the "grand cut off" on the Mississippi, vessels now pass from one point to another in half a mile, in order to accomplish which they had formerly a distance of twenty miles to traverse. Rivers receive a peculiar impress from the geological character of the districts through RIVERS. 283 which they flow. Those of primary or transition countries, where sudden declivities abound, are bold and rapid streams, with steep and high banks, and usually pure waters, owing to the surface not being readily abraded, generally emptying themselves by a single mouth which is deep and unobstructed. The streams of secondary and alluvial districts flow with slow but powerful current, between low and gradually descending banks, which, being composed of soft rocks or alluvial grounds, are easily worn away by the waters, and hence great changes are effected in their channels, and a peculiar colour is given to their streams by the earthy particles with which they are charged. Many rivers have their names from this last circumstance. The Rio Negro, or Black River, which flows into the Amazon, is so called on account of the dark colour of its waters, which are of an amber hue wherever it is shallow, and dark brown wherever the depth is great. The names of the two great streams which unite to form the Nile, the Bahr-el-Abiad, or White River, from the Mountains of the Moon, and the Bahr-el-Azrek, or Blue River, from Abyssinia, refer to the colour which they receive from the quantity of earth with which they are impregnated. The united rivers, for some distance after their junction, preserve their colours distinct. This is the case likewise with the Rhine and'the Moselle, the St. Lawrence and the Ottawa. The Upper Mississippi is a transparent stream, but assumes the colour of the Missouri upon joining that river, the mud of which is as copious as the water can hold in suspension, and of a white soapy hue. The Ohio brings into it a flood of a greenish colour. The bright and dark red waters of the Arkansas and Red River afterwards diminish the whiteness derived from the Missouri, and the volume of the Lower Mississippi bears along a tribute of vegetable soil, collected from the most distant quarters, and of the most various kind, — the marl of the Rocky and the clay of the Black Mountains — the earth of the Alleghanies — and the red-loam washed from the hills at the sources of the Arkansas and the Red River. Mr. Lyell states that water flowing at the rate of three inches per second will tear up fine clay ; six inches per second, fine sand ; twelve inches per second, fine gravel; and three feet per second, stones of the size of an egg. He remarks, likewise, that the rapidity at the bottom of a stream is every where less than in any part above it, and is greatest at the surface ; and that in the middle of the stream the particles at the top move swifter than those at the sides. The ease with which running water bears along large quantities of sand, gravel, and pebbles, ceases to surprise, when we consider that the specific gravity of rocks in water is much less than in air. It is chiefly in primary and transition countries that the rivers exhibit those sudden descents, which pass under the general denomination of falls, and form either cataracts or rapidt. They occur in secondary regions, but more rarely, and the descent is of a more gentle description. The falls are generally found in the passage of streams from the primitive to the other formations. Thus the line which divides the primitive and alluvial formations on the coast of the United States, is marked by the falls or rapids of its rivers, while none occur in the alluvium below. Cataracts are formed by the descent of a river over a precipice which is perpendicular, or nearly so, and depend, for their sublimity, upon the height of the fall, and the magnitude of the stream. Rapids are pro duced by the occurrence of a steeply-inclined plane, over which the flood rushes with great impetuosity, yet without being projected over a precipice. The great rivers of England — the Thames, Trent, and Severn — exhibit no example of either cataract or rapid, but pursue a generally even and noiseless course ; though near their sources, while yet mere brooks and rivulets, most of our home streams present these features in a very miniature manner. A true rapid occurs in the course of the Shannon, just above Lime rick, where the river, forty feet deep, and three hundred yards wide, pours its body of water through and above a congregation of huge rocks and stones, extending nearly half 284 PHYSICAL GEOGRAPHY. a mile, and becomes quite unnavigable. Inglis had never heard of this rapid before arriving in its neighbourhood; but ranks it, in grandeur and effect, above either the Welsh waterfalls, or the Geisbach in Switzerland. The river Adige, in the Tyrol, near JMeran, rushes, with resistless force and deafening noise, down a descent nearly a mile in length, between quiet, green, pastoral banks, present ing one of the most magnificent spectacles to be met with in Europe. The celebrated cataracts of the Nile are, more properly speaking, rapids, as there is no considerable perpendicular fall of the river ; but for a hundred miles at Wady Hafal, the second cataract reckoning upwards, there is a succession of steep descents, and a multitude of rocky islands, among which the river dashes amid clouds of foam, and is tossed in perpetual eddies. It is along the course of the American rivers how ever that the most sublime and imposing rapids are found, rendered so by the great volumes of water contained in their channels. The more remarkable are those of the St. Lawrence, the chief of which, called the Coteau du Luc, the Cedars, the Split Rock, and the Cascades, occur in succession for about nine miles above Montreal and the junction of the Ottawa. At the rapid of St. Anne, on the latter river, the more devout of the Canadian voyayeurs are accustomed land, and implore the protection of the patron saint on their perilous expeditions, before a large cross at the village that bears her name. The words of a popular song have familiarised English ears with this habit of the hardy boatmen : — " Faintly as tolls the evening chime, Our voices keep tune and our oars keep time. Soon as the woods on shore look dim, We'll sing at St. Ann's our parting hymn. Row, brothers, row, the stream runs fast, The Rapids are near, and the daylight's past. '.' Utawa's tide ! this trembling moon Shall see us float over thy surges soon. Saint of this green isle hear our prayers, Oh grant us cool heavens and favouring airs. Blow, breezes, blow, the stream runs fast, The Rapids are near, and the daylight's past." ' < The Kaatcrskill Falls here represented are celebrated in America, for their picturesque beauty. The waters which to Kaaterskill Falls. lUVERS. 285 supply these cascades flow from two small lakes in the Catskill Mountains, on the West Bank of the Hudson. The upper cascade falls one hundred and seventy-five feet, and a few rods below, the second pours its waters over a precipice eighty feet high, passing into a picturesque ravine, the banks of which rise abruptly on each side to the height of a thousand or fifteen hundred feet. In the grandeur of their cataracts, also, the American rivers far surpass those of other countries, though several falls on the ancient continent have a greater perpendicular height, and are magnificent objects. In Sweden, the Gotha falls about 130 feet at Trolhetta, the S/fZ^ Falls of Trolhetta. greatest fall in Europe of the same body of water. The river is the only outlet of a lake, a hundred miles in length and fifty in breadth, which receives no fewer than twenty-four rivers ; the water glides smoothly on, in creasing in rapidity, but quite unruffled, until it reaches the verge of the precipice ; it then darts over it in one broad sheet, which is broken by some jutting rocks, after a descent of about forty feet. Here begins a spectacle of great grandeur. The moving mass is tossed from rock to rock, now heaving itself up in yellow foam, now boiling and tossing in huge eddies, growing whiter and whiter in its descent, till, completely fretted into one beautiful sea of snowy froth, the spray, rising in dense clouds, hides the abyss into which the torrent dashes ; but when momentarily cleared away by the wind, a dreadful gulf is revealed, which the eye cannot fathom. Upon the arrival of a visitor at Trolhetta, a log of wood is sent down the fall, by persons who expect a trifle for the exhibition. It displays the resistless power of the element. The log, which is of gigantic dimensions, is tossed like a feather upon the surface of the water, and is borne to the foot almost in an instant. In Scotland the falls of its rivers are seldom of great size ; but the rocky beds over which they roar and dash in foam and spray — the dark precipitous glens into which they rush — and the frequent wildness of the whole scenery around, are compensating features. The most remarkable instances are 286 PHYSICAL GEOGRAPHY. the Upper and Lower Falls of Foyers, near Loch Ness. At the upper fall, the river precipitates itself, at three leaps, down as many precipices, whose united depth is about 200 feet ; but, at the lower, it makes a de scent at once of 212 feet, and, after heavy rains, exhibits a grand appearance. The fall of the Rhine at Schaff hausen is only 70 feet ; but the great mass of its waters, 450 feet in breadth, gives it an imposing character. The Te- verone, near Tivoli, a comparatively small stream, is precipitated nearly 100 feet : and the Velino, near Terni, falls 300. which is generally considered the finest of the European cataracts. This " hell of waters," as Byron calls it, is of arti ficial construction. A channel was dug by the Consul Curius Dentatus in the year 274 B. c., to convey the waters to the precipice, but having become filled up by a deposition of calcareous matter, it was widened and deepened by order of Pope Paul IV. " I saw," says Byron, " the Cascata del Marmore of Terni twice at different periods ; once from the summit of the precipice, and again from the valley below. The lower view is far to be preferred, if the traveller has time for one only ; but in any point of view, either from above or below, it is worth all the cascades and torrents of SAvitzerland put together." The falls of the Leeambye, otherwise the Zambese, discovered by Dr Livingstone in his remarkable African explorations, are very peculiar. This river seems to lose itself suddenly in the earth, rushing into a fissure of the hard basaltic rock by a leap of a hundred feet ; and a stream of a thousand yards broad, is at once, and for some distance, compressed in a trough scarcely twenty yards wide. Waterfalls appear upon their grandest scale in the American continent. They are not remarkable for the height of the precipices over which they descend, or for the pic turesque forms of the rocky cliffs amid which they are precipitated, like the Alpine cataracts ; but while these are usually the falls of streamlets merely, those of the western world are the rush of mighty rivers. The majority are in the northern part of the continent, but the greatest vertical descent of a considerable body of water is in the southern, at the Falls of Tequendama, where the river of Funza disembogues from the elevated plain or valley of Santa Fe de Bogota. This valley is at a greater height above the level of the sea than the summit of the great St. Bernard, and is surrounded by lofty mountains. It appears to have been formerly the bed of an extensive lake, whose waters were drained off when the narrow passage was forced through which the Funza river now descends from the elevated enclosed valley towards the bed of the Rio Magdalena. Respecting this physical occurrence Gonzalo Ximenes de Quesada, the conqueror of the country, found the following tradition disseminated among the people, which probably Falls of Terni. RIVERS. 287 contains a stratum of truth invested with a fabulous legend. In remote times the inhabitants of Bogota were barbarians, living without religion, laws, or arts. An old man on a certain occasion suddenly appeared among them of a race unlike that of the natives, and having a long bushy beard. He instructed them in the arts, but he brought with him a malignant, although beautiful woman, who thwarted all his benevolent enterprises. By her magical power she swelled the current of the Funza, and inundated the valley, so that most of the inhabitants perished, a few only having found refuge in the neighbouring mountains. The aged visitor then drove his consort from the earth, and she became the moon. He next broke the rocks that enclosed the valley on the Tequendama side, and by this means drained off the waters. Then he introduced the worship of the sun, appointed two chiefs, and finally withdrew to a valley, where he lived in the exercise of the most austere penitence during 2000 years. The Tequendama cataract is remarkably picturesque. The river a little above it is 144 feet in breadth, but at the crevice it is much narrower. The height of the fall is 574 feet, and the column of vapour that rises from it is visible from Santa Fe at the distance of 17 miles. At the foot of the precipice the vegetation has a totally different appearance from that at the summit, and the traveller, following the course of the river, passes from a plain in which the cereal plants of Europe are cultivated, and which abounds with oaks, elms, and other trees resembling those of the temperate regions of the northern hemisphere, and enters a country covered with palms, bananas, and sugar-canes. In Northern America, however, we find the greatest of all cataracts, that of the Niagara, the sublimest object on earth, according to the general opinion of all travellers. More varied magnificence is displayed by the ocean, and giant masses of the Andes and Himalaya ; but no single spectacle is so striking and wonderful as the descent of this sea-like flood, the overplus of four extensive lakes. The river is about thirty-three miles in length, extending from lake Erie to lake Ontario, and three quarters of a mile wide at the fall. There is nothing in the neighbouring country to indicate the vicinity of the astonishing phenomenon here exhibited. Leaving out lake Erie, the traveller passes over a level though somewhat elevated plain, through which the river flows tranquilly, bordered by fertile and beautiful banks ; but soon a deep awful sound, gradually growing louder, breaks upon the ear — the roar of the distant cataract. Yet the eye discerns no sign of the spectacle about to be disclosed until a mile from it, when the water begins to ripple, and is broken into a series of dashing and foaming rapids. After passing these, the river becomes more tranquil, though rolling onwards with tremendous force, till it reaches the brink of the great precipice. The fall itself is divided into two unequal portions by the intervention of Goat Island, a fa9ade near 1000 feet in breadth. The one on the British side of the river, called the Horse Shoe fall, from its shape, according to the most careful estimate, is 2100 feet broad, and 149 feet 9 inches high. The other or American fall is 1140 feet broad, and 164 feet high. The former is far superior to the latter in grandeur. The great body of the water passes over the precipice with such force, that it forms a curved sheet which strikes the stream below at the distance of 50 feet from the base, and some travellers have ventured between the descending flood and the rock itself. Hannequin asserts that four coaches might be driven abreast through this awful chasm. The quantity of water rolling over these falls has been estimated at 670,250 tons per minute. It is impossible to appreciate the scene created by this immense torrent, apart from its site. " The thoughts are strange that crowd into my brain, While I look upward to thee. It would seem As if God pour'd thee from his hollow hand, And hung his bow upon thine awful front ; 288 PHYSICAL GEOGRAPHY. And spoke in that loud voice which seem'd to him Who dwelt in Patmos for his Saviour's sake, The sound of many waters ; and had bade Thy flood to chronicle the ages back, And notch his centuries in the eternal rocks Deep callcth unto deep. And what are we, That hear the question of that voice sublime Oh ! what are all the notes that ever rung From war's vain trumpet, by thy thundering side ? Yea, what is all the riot man can make, In his short life, to thy unceasing roar ? And yet, Bold Babbler ! what art thou to Him. \Vho drown'd a world, and heap'd the waters far Above its loftiest mountains ? — a light wave, That breaks, and whispers -of its Maker's might." It has been remarked that at Niagara, several objects composing the chief beauty of other celebrated waterfalls are altogether wanting. There are no cliffs reaching to an extraordinary height, crowned with trees, or broken into picturesque and varied forms ; for, though one of the banks is wooded, the forest scenery on the whole is not imposing. The accompaniments, in short, rank here as nothing. There is merely the display, on a scale elsewhere unrivalled, of the phenomena appropriate to this class of objects. There is the spectacle of a falling sea, the eye filled almost to its utmost reach by the rushing of mighty waters. There is the awful plunge into the abyss beneath, and the reverberation thence in endless lines of foam, and in numberless whirlpools and eddies ; there are clouds of spray that fill the whole atmosphere, amid which the most brilliant rainbows, in rapid succession, glitter and disappear ; above all, there is the stupendous sound, of the peculiar character of which all writers, with their utmost efforts, seem to have vainly attempted to convey an idea. Bouchette describes it as " grand, commanding, and majestic, filling the vault of heaven when heard in its fulness " — as "a deep, round roar, an alternation of muffled and open sounds, to which there is nothing exactly corresponding." Captain Hall compares it to the ceaseless, rumbling, deep-monotonous sound of a vast mill, which, though not very poetical, is generally considered as approaching near to the reality. Dr. Reed states, " it is not like the sea ; nor like the thunder ; nor like any thing I have heard. There is no roar, no rattle ; nothing sharp or angry in its tones ; it is deep, awful. One." The diffusion of the noise varies according to the state of the atmosphere and the direction of the wind, but it may be heard under favourable circumstances through a distance of forty-six miles : at Toronto, across Lake Ontario. To the geologist the Niagara falls have interest, on account of the movement which it is supposed has taken place in their position. The force of the waters appears to be wearing away the rock over which they rush, and gradually shifting the cataract higher up the river. It is conceived that by this process it has already receded in the course of ages through a distance of more than seven miles, from a point between Queenstown and Lewiston, to which the high level of the country continues. The rate of procession is fixed, according to an estimate, mentioned by Mr. M'Gregor, at eighteen feet during the thirty years previous to 1810 ; but he adds another more recent, which raises it to one hundred and fifty feet in fifty years. The following account of a visit to the Falls of Niagara has been communicated by Mr. N. Gould. It forms a part of his unpublished Xotes on America and Canada. " My attention had been kept alive, and I was all awake to the sound of the cataract ; but, though within a few miles, I heard nothing. A cloud hanging nearly steady over the forest, was pointed out to me as the 'spray cloud;' at length we drove up to For- syth's hotel, and the mighty Niagara was full in view. My first impression was that RIVERS. 289 of disappointment — a sour sort of deep disappointment, causing, for a few minutes, a kind of vacuity ; but, while I mused, I began to take in the grandeur of the scene. This impression is not unusual on viewing objects beyond the ready catch of the senses ; Stone- henge and St. Paul's cathedral seldom excite much surprise at first sight ; the enormous Pyramids, I have heard travellers say, strike with awe and silence on the near approach, but require time to appreciate. The fact is, that the first view of Niagara is a bad one ; and the eye, in this situation, can comprehend but a small part of the wonderful scene. You look down upon the cataract instead of up to it ; the confined channel, and the depth of it, prevent the astounding roar which was anticipated ; and, at the same time, the eye wanders midway between the water and the cloud formed by the spray, which it sees not. After a quarter of an hour's gaze, I felt a kind of fascination — a desire to find myself gliding into eternity in the centre of the Grand Fall, over which the bright green water appears to glide, like oil, without the least commotion. I approached nearly to the edge of the ' Table Rock,' and looked into the abyss. A lady from Devonshire had just retired from the spot; I was informed she had approached its very edge, and sat with her feet over the edge — an awful and dangerous proceeding. Having viewed the spot, and made myself acquainted with some of its localities, I returned to the hotel (Forsyth's) which, as well as its neighbouring rival, is admirably situated for the view ; from my chamber-window I looked directly upon it, and the first night I could find but little sleep from the noise. Every view I took increased my admira tion ; and I began to think that the other Falls I had seen were, in comparison, like runs from kettle-spouts on hot plates. I remained in this interesting neighbourhood five days, and saw the Fall in almost every point of view. From its extent, and the angular line it forms, the eye cannot embrace it all at once ; and, probably, from this cause it is that no drawing has ever yet done justice to it. The grandest view, in my opinion, is at the bottom, and close to it on the British side, where it is awful to look up through the spray at the immense body as it comes pouring over, deafening you with its roar ; the lighter spray, at a considerable distance, hangs poised in the air like an eternal cloud. The next best view is on the American side, to reach which you cross in a crazy ferry-boat : the passage is safe enough, but the current is strongly agitated. Its depth, as near to the falls as can be approached, is from 180 to 200 feet. The water, as it passes over the rock, where it is not whipped into foam, is a most beautiful sea-green, and it is the same at the bottom of the Falls. The foam, which floats away in large bodies, feels and looks like salt water after a storm : it has a strong fishy smell. The river, at the ferry, is 1170 feet wide. There is a great quantity of fish, particularly sturgeon and bass, as well as eels ; the latter creep up against the rock under the Falls, as if desirous of finding some mode of surmounting the heights. Some of the visitors go under the Falls, an undertaking more curious than pleasant. Three times did I go down to the house, and once paid for my guide and balking dress, when something occurred to prevent me. The lady before alluded to performed the ceremony, and it is recorded, with her name, in the book, that she went to the furthest extent that the guides can or will proceed. It is described as like being under a heavy shower-bath, with a tremendous whirlwind driving your breath from you, and causing a peculiarly unpleasant sensation at the chest ; the footing over the debris being slippery, the darkness barely visible, and the roar almost deafening. In the passage you kick against eels, many of them unwilling to move, even when touched : they appear to be endeavouring to work their way up the stream." Supposing the cataract to be receding at the rate of fifty yards in forty years, as it is stated by Captain Hall, the ravine which extends from thence to Queenstown, a dis- 290 PHYSICAL GEOGRAPHY. tance of seven miles, will have required nearly ten thousand years for its excavation ; and, at the same rate, it will require upwards of thirty-five thousand years for the falls to recede to Lake Erie, a distance of twenty -five miles. The draining of the lake, which is not more than ten or twelve fathoms in average depth, must then take place, causing a tremendous deluge by the sudden escape of its waters. In addition to the gradual erosion of the limestone, which forms the bed of the Niagara at and above the falls, huge masses of the rock are occasionally detached, by the undermining of the soft shale upon which it rests. This effect is produced by the action of the spray powerfully thrown back upon the stratum of shale ; and hence has arisen the great hollow between the descending flood and the precipice. An immense fragment fell on the 28th of December, 1828, with a crash that shook the glass vessels in the adjoining inn, and was felt at the distance of two miles from the spot. By this disintegration, the angular or horse-shoe form of the great fall was lessened, and its grandeur heightened by the line of the torrent becoming more horizontal. A similar dislocation had occurred in the year 1818 ; and the aspect of the precipice is always so threatening, owing to the wearing away of the lower stratum, as to render it an affair of some real hazard to venture between the falling waters and the rock. Miss Martineau undertook the enterprise, clad in the oil-skin costume used for the expedition, and thus remarks concerning it : — "A hurricane blows up from the caul dron ; a deluge drives at you from all parts ; and the noise of both wind and waters, reverberated from the cavern, is inconceivable. Our path was sometimes a wet ledge of rock, just broad enough to allow one person at a time to creep along : in other places we walked over heaps of fragments, both slippery and unstable. If all had been dry and quiet, I might probably have thought this path above the boiling basin dangerous, and have trembled to pass it ; but, amidst the hubbub of gusts and floods, it appeared so firm - a footing, that I had no fear of slipping into the cauldron. From the moment that I perceived we were actually behind the cataract, and not in a mere cloud of spray, the enjoyment was .intense. I not only saw the watery curtain before me like tempest- driven snow, but, by momentary glances, could see the crystal roof of this most wonderful of Nature's palaces. The precise point where the flood quitted the rock was marked by a gush of silvery light, which of course was brighter where the waters were shooting for ward, than below, where they fell perpendicularly." There have been several hairbreadth escapes, and not a few fatal accidents, at Niagara, the relation of which is highly illus trative of Indian magnanimity. Tradition preserves the memory of the warrior of the red race, who got entangled in the rapids above the falls, and, seeing his fate inevitable, calmly resigned himself to it, and sat singing in his canoe till buried by the torrent in the abyss to which it plunges. The celebrated Chateaubriand narrowly escaped a similar fate. On his arrival he had repaired to the fall, having the bridle of his horse twisted round his arm. "While he was stopping to look down, a rattlesnake stirred among the neighbouring bushes. The horse was startled, reared, and ran back towards the abyss. He could not disengage his arm from the bridle ; and the horse, more and more frightened, dragged him after him. His fore-legs were all but off the ground ; and, squatting on the brink of the precipice, he was upheld merely by the bridle. He gave himself up for lost ; when the animal, astonished at this new danger, threw itself forward with a pirouette, and sprang to the distance of ten feet from the edge of the abyss. The erosive action of running water, which is urging the Niagara falls towards Lake Erie, is strikingly exhibited by several rivers which penetrate through rocks and beds of compact strata, and have either scooped out their own passage entirely, or widened and deepened original tracks and fissures in the surface, into enormous wall-sided valleys. The current of the Simeto — the largest Sicilian river round the base of Etna — was crossed by a great stream of lava about two centuries and a half ago ; but, since that era, RIVERS. 291 Natural Bridge, Virginia. the river Has completely triumphed over the barrier of homogeneous hard blue rock that intruded into its channel, and cut a passage through it from fifty to a hundred feet broad, and from forty to fifty feet deep. The formation of the magnificent rock-bridge which overhangs the course of the Cedar creek, one of the natural wonders of Virginia, is very probably due in part to the sol- / vent and abrading power of the stream. This sublime curiosity is 213 feet above the river, 60 feet wide, 90 long, and the thickness of the mass at the summit of the arch is about 40 feet. The bridge has a coating of earth, which gives growth to several large trees. To look down from its edge into the chasm in spires a feeling answering to the words of Shakspeare: — " Come on, sir ; here's the place : — stand still. — How fearful And dizzy 'tis, to cast one's eyes so low ! " Few have resolution enough to walk to the parapet, in order to peep over it. But if the view from the top is painful and intolerable, that from below is pleasing in an equal degree. The beauty, elevation, and lightness of the arch, springing as it were up to heaven, present a striking instance of the graceful in combination with the sublime. This great arch of rock gives the name of Eockbridge to the county in which it is situated, and affords a public and com modious passage over a valley which cannot be crossed elsewhere for a considerable distance". Under the arch, thirty feet from the water, the lower part of the letters G. W. may be seen, carved in the rock. They are the initials of Washington, who, when a youth, climbed up hither, and left this record of his adventure. We have several examples of the disappearance of rivers, and their emergence after pursuing for some distance a subterranean course. In these cases a barrier of solid rock, overlaying a softer stratum, has occurred in their path ; and the latter has been gradually worn away by the waters, and a passage been constructed through it. Thus the Tigris, about twenty miles from its source, meets with a mountainous ridge at Diglou, and, running under it, flows out at the opposite side. The Rhone, also, soon after coming within the French frontier, passes under ground for about a quarter of a mile. Milton, in one of his juvenile poems, speaks of the " Sullen Mole, that runneth underneath ; " and Pope calls it, after him, the " Sullen Mole, that hides his diving flood." The Hamps and the Manifold, likewise — two small streams in Derbyshire — flow in separate subterraneous channels for several miles, and emerge within fifteen yards of each other in the grounds of Ham Hall. That these are really the streams which are swal lowed up at points several miles distant, has been frequently proved by watching the exit of various light bodies that have been absorbed at the swallows. At their emergence, the waters of the two rivers differ in temperature about two degrees — an obvious proof that they do not anywhere intermingle. On the side of the hill, which is overshadowed with spreading trees, just above the spot where the streams break forth into daylight, there is a rude grotto, scooped out of the rock, in which Congreve is said to have written 292 PHYSICAL GEOGRAPHY. his comedy of the "Old Bachelor" and a part of his "Mourning Bride." In Spain a similar phenomenon is exhibited by the Guadiana ; but it occurs under different circum stances. It disappears for about seven leagues — an effect of the absorbing power of the soil — the intervening space consisting of sandy and marshy grounds, across which the road to Andalusia passes by a long bridge or causeway. The river reappears with greater power, after its dispersion, at the Ojos de Guadiana — the Eyes of the stream. Many rivers are subject to a considerable elevation of the level of their waters. This is periodical or irregular in its occurrence, according to the nature of the producing cause. Casual temporary floodings, as the effect of extraordinary rains, are common to the streams of most countries, and sometimes occasion great changes of the surface, and destruction of life and property. One of the most remarkable instances of this kind in modern times, occurred on the 4th of August, 1829, in Scotland, when the Nairn, Spey, and Findhorn rose above their natural boundaries, and spread a devastating deluge over the surrounding country. The rain which produced this flood fell chiefly on the Monadh- leadh Mountains, where the rivers in question have their feeders, situated between the south of Loch Ness and the group of the Cairngorums. Sir Thomas Dick Lauder, in his interesting account of this inundation, considers the westerly winds, which prevailed for some time previously after a season of unusual heat, to have produced a gradual accumu lation of vapour, somewhere north of our island ; and the column being suddenly impelled by a strong north-easterly blast, it was driven towards the south-west, till arrested in its course by the lofty mountains upon which it discharged itself in torrents perfectly unex ampled. The rain fell occasionally in heavy drops, but was for the most part broken by the blast into extremely minute particles, so thick, that the very air itself seemed to be descending in one mass of water upon the earth. It deluged every house whose windows were exposed to the south-east. The lesser animals, the birds, and especially game of all kinds, were destroyed in great numbers, by the rain alone ; and the mother partridge, with her progeny and mate, were found chilled to death amidst the drenching wet. At Huntly Lodge, according to an accurate observation, between five o'clock of the morning of the 3rd of August and the same hour of the succeeding day, there fell 3J inches of rain, or about one-sixth of our annual allowance of rain descended there in twenty-four hours. This was at a considerable distance from the mountains — the central scene of the rain — where its quantity must have been prodigiously greater, sufficient to account for the tremendous flood that followed, far exceeding in its rise, duration, and havoc, any other that ever affected the same locality. The Findhorn and Spey assumed the appearance of inland seas ; and, when the former began to ebb, a fine salmon was driven ashore and captured, at an elevation of fifty feet above its ordinary level. Most of the rivers of the temperate zones are subject to these irregular floodings from the same cause, especially those which take their rise in high mountain regions, the St. Lawrence being the most remarkable exception, the level of which is not affected by either rains or drought. The vast lakes from which this river issues, furnish its channel with an inexhaustible supply of water, and present a surface too extensive to be sensibly elevated by any extraordinary rains. A strong westerly wind, however, will affect the level of the St. Lawrence, and occasion a rise of six feet in the waters to the eastern extremity of Lake Erie. An easterly wind also upon the Orinoco will check its current, elevate the upper part of the stream, and force its waters into the channels of its tributaries, giving them a backward flow, and causing them to be flooded ; and a northerly wind will drive the Baltic up the mouths of the Oder, and raise its level for a considerable distance. In a similar manner, the Neva rises when a strong wind blows from the Gulf of Finland ; and that occurrence, — taking place coincidently with high water and the breaking up of the ice, would create an inundation sufficient to drown the whole population of St. Petersburg, and convert that RIVEKS. 293 brilliant capital, with all its sumptuous palaces, into a chaotic mass of ruins. We have the materials of this statement from M. Kohl. The Gulf of Finland runs to a point as it approaches the mouth of the Neva, where the most violent gales are always those from the west ; so that the mass of waters on such occasions is always forcibly impelled towards the city. The islands forming the delta of the Neva, on which St. Petersburg stands, are extremely low and flat ; and the highest point in the city is probably not more than twelve or fourteen feet above the average level of the sea. A rise of fifteen feet is therefore enough to place all St. Petersburg under water, and a rise of thirty feet is enough to drown almost every human being in the place. Hence the inhabitants of the capital are in constant danger of destruction at the period referred to, and can never be certain that the 500,000 of them may not, within the next twenty-four hours, be driven out of their houses, to find, in multitudes of instances, a watery grave. This is not a chimerical danger ; for, during its short continuance, the city of the Czar has experienced some formidable inundations. The only hope of this apparently doomed city is, that the three circumstances may never be coincident, namely, high water, the break ing up of the ice, and a gale of wind from the west. It is nevertheless true, that the wind is very often westerly during spring, and the ice floating in the Neva and the Gulf of Finland is cf a bulk amply sufficient to oppose a formidable obstacle to the egress of the water ; so that it will not be surprising if St. Petersburg, after suddenly rising like a meteor from the swamps of Finland, should still more suddenly be extinguished in them. The periodical rise of rivers is either diurnal, semi-annual, or annual, and proceeds from a variety of causes. Where streams descend immediately from mountains covered with snow, the heat of the sun melting the snow produces high water every day, the increase being the greatest in the hottest days. In Peru and Chili there are small rivers which flow only during the day, because they are fed entirely by the melting of the snow Valley of the Concon, Chili. upon the summit of the Andes, which takes place only when the solar influence is in action. In Hindustan, and some parts of Africa, rivers exist, which, though they flow night and day, are, from the accession of snow-water, the greatest by day. Those rivers also which fall into the sea have their level daily varied by the tidal wave for some distance from their mouths, the extent through which the influence of the tides is felt being modified by the breadth and shape of their channels and the force of their current. The wider and more direct the bed of a stream communicating with the ocean, and the 294 PHYSICAL GEOGRAPHY. slower its motion, the farther the tide will penetrate ; whereas a narrow and sinuous course, and a great velocity, offer obstructions to its progress. The tide of the Atlantic is perceived four hundred miles along the course of the Amazon, and that of the German Ocean extends about seventy miles up the Thames. Important facilities are afforded to the navigation of many rivers by this circumstance, for they are only accessible to vessels of large burden at high water. The rapid of Eichelieu, on the St. Lawrence, where the river contracts, and has its course obstructed by rocks, impedes the navigation between Montreal and Quebec, except at high tide, when the water rises fifteen or eighteen feet, and the rapid entirely disappears. A semi-annual or an annual rise alone distinguishes the rivers of inter-tropical regions and of countries bordering on the torrid zone. The semi-annual rise is a feature of those rivers which drain high mountain ranges, and pro ceeds from the two independent causes, of the melting of the snows in spring or summer, and the great seasonal rains to which such districts are subject. The rivers which have only one annual rise are influenced by the latter cause alone, or by the two acting coin- cidently, and producing a grand periodical flood. The Tigris rises twice in the year— first, and most remarkably, in April, in consequence of the melting of the snows in the mountains of Armenia ; and secondly, in November, through an accession from the pe riodical rains. The Mississippi likewise is subject to two rises in the year — one about January, occasioned by the periodical rains that fall towards the lower part of its course ; but the grand flood commences in March, and continues till June, proceeding from the melting of the ice in the upper part of the continent, where the Missouri and other tribu tary streams have their origin. A very striking spectacle is exhibited by this river in the season of inundation. It rises from forty to fifty feet in some parts of its course, and is from thirty to a hundred miles wide, all overshaded with forest, except the interior stripe consisting of its bed. The water stands among the trees, from ten to fifteen feet in height, and the appearance is exactly that of a forest rising from a lake, with its waters in rapid motion. For the protection of the cultivated lands, and to prevent their conversion into permanent swamps, an embankment, called the Lessee, has been raised, which extends two hundred miles on the eastern shore of the river, and three hundred on the western. In Asia, the Ganges, Indus, and Euphrates exhibit inundations upon a similarly great scale. The Euphrates slightly increases in January, but the grand flood begins soon after the middle of March. It attains its height about the 20th of May, after which it falls rapidly till June. The decrease then proceeds gradually until the middle of November, when the stream is at its lowest. The rise of the water at Anah, above the site of ancient Babylon, occasionally amounts to eighteen feet,^ sometimes entering that town, running with a velocity exceeding five miles an hour. The moment that the waters of the river recede, the rice and grain crops are sown in the marshes, and villages of slightly made reed cottages are reared in their neighbourhood. These last,^ in consequence of being suffered to remain too long, are often surprised by the returning inundation, and it is no uncommon spectacle for their occupants to be seen following the floating villages in canoes, for the purpose of recovering their property. But of all inundations, that of the Nile, if not the most extensive, is the most regular, and has become the most celebrated, from the knowledge of it going back to the earliest periods to which history recurs. The rise of the river commences about the time of the summer solstice, attains its maximum height at the autumnal equinox, remains stationary for some days, and then gradually diminishes till the time of the winter solstice, ancients, unacquainted with the climate of the interior country from which it descends and not caring in general to inquire for physical causes, possessing also a very limited knowledge of terrestrial phenomena, deemed the annual overflow of the Nile a unique event, and attributed it to the special interference of a supernatural power. Lucretius, RIVERS. 295 however, who soared in many respects above the prejudices of his age concerning the natural world, assigned it to a proper cause ; though he wrongly ascribes influence to the Etesian wind, and shows his imperfect acquaintance with the geography of the globe, by supposing the occurrence without a parallel. " The Nile now calls us, pride of Egypt's plains : Sole stream on earth its boundaries that o'erflows Punctual, and scatters plenty. When the year Now glows with perfect summer, leaps its tide Proud o'er the champaign ; for the north wind, no\v Th' Etesian breeze, against its mouth direct Blows with perpetual winnow ; every surge Hence loiters slow, the total current swells, And wave o'er wave its loftiest bank surmounts. For that the fix'd monsoon that now prevails Flows from the cold stars of the northern pole, None e'er can doubt ; while rolls the Nile adverse Full from the south, from realms of torrid heat, Haunts of the Ethiop tribes ; yet far beyond First bubbling, distant, o'er the burning line. Then ocean, haply, by th' undevious breeze Blown up the channel, heaves with every wave Heaps of high sand, and dams its wonted course ; Whence, narrower, too, its exit to the main, And with less force the tardy stream descends. Or, towards its fountain, ampler rains, perchance, Fall, as th' Etesian fans, now wide unfurl'd, Ply the big clouds perpetual from the north Full o'er the red equator ; where condensed, Ponderous and low, against the hills they strike, And shed their treasures o'er the rising flood. Or, from the Ethiop -mountains, the bright sun Now full matur'd with deep-dissolving ray May melt th' agglomerate snows, and down the plains Drive them, augmenting hence, th' incipient stream." The annual overflow of the Nile is now well known to proceed from the heavy periodical rains within the tropics. They fall in copious torrents upon the great plateau of Abyssinia, which rises, like a fortress, 6000 feet above the burning plains with which it is surrounded. The vapours, arrested and condensed by this highland rampart, often densely shroud Ankobar, the capital, while, whenever the curtain of mist is withdrawn, the strange contrast is presented of the sulphureous plains, visible below, where the heat is 90°, and the drought excessive. A peculiar character has been given to this district by the violence of the periodical rains. Bruce speaks of the mountains of this table land, not remarkable for their height, but for their number and uncommon forms. " Some of them are flat, thin, and square, in shape of a hearth-stone or slab, that scarce would seem to have base sufficient to resist the winds. Some are like pyramids, others like obelisks or prisms, and some, the most extraordinary of all, pyramids pitched upon their points, with their base uppermost." Mr. Salt confirms this delinea tion in the main. The peculiar shapes referred to have been formed by the action of the torrents discharged from the clouds, which have, for ages, been skeletonising •the country, dismantling the granite with its kindred masses of the softer deposits, gradually wearing away also these harder rocks, and carrying along the soil of Ethiopia, strewing it upon the valley of the Nile, to the shores of the Mediterranean. When Bruce was ascending Taranta, a sudden noise was heard on the heights louder than the 296 PHYSICAL GEOGRAPHY. loudest thunder, and, almost directly afterwards, a river, the channel of which had been dry, came down in a stream several feet in depth, and as broad as the whole bed. Hence the steeple and obelisk form of the rocks, with their naked aspect, — which has, not unaptly, been compared to bones stripped of their flesh. In the tropical countries of South America, the sea sonal rains are, perhaps, more intensely copious than in any other part of the torrid zone, and the floods of its rivers are of corresponding magnitude. At the mission of San Antonio de Javita, on the Orinoco, during the wet season, the sun and stars are seldom visible, and Humboldt was told by the padre, that it sometimes rained for four and five months without intermission. The traveller collected there, in five hours, 21 lines of water in height on the first of May, and 14 lines on the 3d, in three hours ; whereas at Paris there fall only 28 or 30 lines in as many weeks. Humboldt traces the transition from the one great season of drought to that of rain, which divides the year, in an interesting manner, with the atmospheric phenomena which accompany the change. About the middle of February in the valleys of Araqua, he observed clouds forming in the evening, and in the beginning of March the accumulation of vesicular vapours became visible. "Nothing," he remarks, in beautifully graphic style, "can equal the purity of the atmosphere from December to February. The sky is then constantly without clouds, and should one appear, it is a phenomenon that occupies all the attention of the inhabitants. The breeze from the east and north-east blows with violence. As it always carries with it air of the same temperature, the vapours cannot become visible by refrigeration. Towards the end of February and the beginning of March the blue of the sky is less intense ; the hygrometer gradually indicates greater humidity ; the stars are sometimes veiled by a thin stratum of vapours ; their light ceases to be tranquil and planetary ; and they are seen to sparkle from time to time at the height of 20° above the horizon. At this period the breeze diminishes in strength, and becomes less regular, being more frequently interrupted by dead calms. Clouds accumulate towards the south-east, appearing like distant mountains with distinct outlines. From time to time they are seen to separate from the horizon, and traverse the celestial vault with a rapidity which has no correspondence with the feebleness of the wind that prevails in the lower strata of RIVERS. 297 the air. At the end of March the southern region of the atmosphere is illuminated by small electric explosions, like phosphorescent gleams, confined to a single group of vapours. From this period the breeze shifts at intervals, and for several hours, to the west and south-west, affording a sure indication of the approach of the rainy season, which, on the Orinoco, commences about the end of April. The sky begins to be over cast, its azure colour disappears, and a gray tint is uniformly diffused over it. At the same time the heat of the atmosphere gradually increases, and, instead of scattered clouds, the whole vault of the heavens is overspread with condensed vapours. The howling monkeys begin to utter their plaintive cries long before sunrise. The atmo spheric electricity, which, during the period of the greatest drought, from December to March, had been almost constantly in the day-time from 1'7 to 2 lines to Volta's electro meter, becomes extremely variable after March. During whole days it appears null, and again, for some hours, the pith-balls of the electrometer diverge from three to four lines. The atmosphere, which in the torrid as in the temperate zone is generally in a state of positive electricity, passes alternately, in the course of eight or ten minutes, to a negative state. The rainy season is that of thunder-storms. The storm rises in the plains two hours after the sun passes through the meridian, and therefore shortly after the period of the maximum of the diurnal heat in the tropics. In the inland districts it is exceedingly rare to hear thunder at night or in the morning, nocturnal thunder-storms being peculiar to certain valleys of rivers which have a particular climate." The substance of the explanation of the preceding phenomena, by the philosophic writer of the statement, may be briefly given : The season of rains and thunder in the northern equinoctial zone coincides with the passage of the sun through the zenith of the place, the cessation of the breezes, or north-east winds, and the frequency of calms, and furious currents of the atmosphere from the south-east and south-west, accompanied with a cloudy sky. While the breexe from the north-east blows, it prevents the atmosphere from being saturated with moisture. The hot and loaded air of the torrid zone rises, and flows off again towards the poles, while inferior currents from these last, bringing drier and colder strata, take the place of the ascending columns. In this manner the humidity, being prevented from accumulating, passes off towards the temperate and colder regions, so that the sky is always clear. When the sun, entering the northern signs, rises towards the zenith, the breeze from the north-east softens, and at length ceases ; this being the season at which the difference of temperature between the tropics and the contiguous zone is least. The column of air resting on the equinoctial zone becomes replete with vapours, because it is no longer renewed by the current from the pole ; clouds form in this atmosphere, saturated and cooled by the effects of radiation and the dilatation of the ascending air, which increases its capacity for heat in proportion as it is rarefied. Electricity accumulates in the higher regions, in consequence of the formation of the vesicular vapours, the precipitation of which is constant during the day, but generally ceases at night. The showers are more violent, and accompanied with electrical explosions, shortly after the maximum of the diurnal heat. These phenomena continue until the sun enters the southern signs, when the polar current is re-established, because the difference between the heat of the equi noctial and temperate regions is daily increasing. The air of the tropics being thus renewed, the rains cease, the vapours are dissolved, and the sky resumes its azure tint. The Orinoco, when in flood, inundates a vast extent of country, six hundred miles in length and from sixty to ninety in width. Its waters cover the savannahs along its banks to the depth of twelve or fourteen feet, giving to them a lake-like appearance, in the midst of which farm-houses and villages are seen rising on islands but little elevated above the surface. The wild cattle perish in great numbers, and fall an easy prey to the carrion- vultures and alligators. In one part of the river Humboldt found marks of recent inun- 298 PHYSICAL GEOGRAPHY. dation at 45 feet above the ordinary level ; but above the greatest height to which its waters are now elevated, he traced its ancient action at 106 or even 138 feet. " Is this river, then," inquires he, " the Orinoco, which appears to us so imposing and majestic, merely the feeble remnant of those immense currents of fresh water which, swelled by Alpine snows or by more abundant rains, every where shaded by dense forests, and destitute of those beaches that favour evaporation, formerly traversed the regions to the east of the Andes, like arms of inland seas ? What must then have been the state of those low countries of Guiana, which now experience the effects of annual inundations ! What a prodigious number of crocodiles, lamartines, and boas must have inhabited these vast regions, alternately converted into pools of stagnant water and arid plains ! The more peaceful world in which we live has succeeded to a tumultuous world. Bones of masta- dons and real American elephants are found dispersed over the platforms of the Andes. The megatherium inhabited the plains of Uruguay. By digging the earth more deeply in high valleys, which at the present day are unable to nourish palms or tree-ferns, we discover strata of coal, containing gigantic remains of monocotyledonous plants. There was therefore a remote period when the tribes of vegetables were differently distributed, when the animals were larger, the rivers wider and deeper. There stop the monuments of nature which we can consult." This grand stream, when more than five hundred miles inland, has a breadth measuring upwards of three miles. In its regular rise and fall, with the delta at its mouth, the numerous crocodiles, the cataracts or rapids in the upper part of its course, and the level plains of the lower, it bears a close resemblance to the Nile. It is remarkable also for the varying direction of its course, setting out from east to west, then turning north, and finally running from west to east, so as to bring its estuary and source into nearly the same longitude. The disturbance caused by the collision of the powerful current of the river with the Atlantic, led the inexpert early navigators to denominate that part of the ocean the Bay of Sadness, Golfo Triste; and the channel between the continent and the island of Trinidad, they similarly styled the Dragon's Mouth, Boca del Drago. The Orinoco is historically memorable as having been entered by Columbus, who sagaciously inferred from its volume the continental character of the adjoining region. It is physically remarkable for its basin so running into that of the Amazon, that water communication subsists naturally between the two primary streams. This fact has already been mentioned ; but as a rare feature in the physics of the earth, and as illustrating the energy of Humboldt, the great traveller of modern times, by whom it was decisively determined, we may recur to it. He and Bonpland left Caraccas in the year 1800, crossed the valleys of Aragua, and the Llanos of Calabozo — excellent pastures, which separate the cultivated part of Venezuela from the region of the forests and missions — and embarked at San Fernando, on the Rio Apure, to follow its course downwards to its discharge into the principal branch of the Orinoco. They then ascended the Orinoco, passing its two great cataracts of Apures and Maypures, and reached the village of San Fernando de Atabapo, situated at the junction of the Guaviare and Atabapo, and near lat. 4° N. Here they left the river, and sailed up the Atabapo to the mouth of the Rio Temi; which latter they followed as far as its confluence with the Tuanimi, and arrived at the village of San Antonio de Javita> formerly mentioned as remarkable for its amount of rain. From this point the Indians carried their boat across the isthmus which separates the Tuamini from the Rio Pimichin, the travellers following on foot, passing through dense forests, often in danger from the number of snakes that infested the marshes. Embarking on the Pimichin, they came in four hours and a half into the Rio Negro. " The morning," says Humboldt, " was cool and beautiful. We had been confined thirty-six days in a narrow canoe, BO unsteady Mi r RING C O EXPLANATION .Hut' in thf ca*l, 0UV Bifurcati*>n tmd Its amn&rcon with t} nil'ER llA/.]/".Y Dfsitin*! from .tstron ('/•...•rv.iftWAr BARQN VON HUM BO t D T PLANOrTME LAKE VASIVA PLAKOf r»t NARBOWSt CATARACTS Of MAYPURES ' 1..,. Hi,/o*,.i/i i> Maiiivas Indians r^"i?VM'"0 REFERENCE 22 There is a piwtage of three days journey between the. hi.- Siapa, and the Ru> tf,n.t,.i '£> Raudal de i ruaharibos . wtth .1 ht.fys , thf uiJud'itantt REFERENCE 1 fa the banks rftht Vachad*. McssV BumbaUt and Banpland observed tt&ns oftkcLt Cenampmides . 'i Thf water ffthr Jtivers Zama,, Mataveni. and UmA Leafier of the Guaypunabis solitary granite rvck- , 5 J/r.t.«7Tv>,v df Danpabo , very fade known,. 27 Curoaaiuia Indiana wht> n Jin; its and great 28 Second dwtlhnq place Carom', thf *' the Ku* I'en- 32 Her* llu,ub.Mt <•»<< &>fyl.tn,i timnd »•//./ as '/^' - "'•' a*.wi-*v/ «fc- • nk- «'/rf/ 15 TV fvrluffufst . i...*/f M../ Mm/ betffsrt >/'.//;;,./ htttiiim urui ihf Bnut/ 16 7X Oritit'tV hv itself uii" the .iiiHtztw in J.nt •/ "/•'/..'/•*/ with bbtt-k water 16 Ai> Siapt tv Idapa , with white 19 Bsre ihs />A//.>> *fr Hat'M^urf yAiw .#ki>h pa* \'Z 'Ifo Indians afJtnUa and Dtn-ipe cunuretl rftfu Guainia and ,'t'ttts tmrula,.wt ttese togefaer and .a ./ -//- •f->nt I .-/ .'< .t.i\.i idurnev irwm flfcrr •/-v .'/' i t'trt't'toirertn&.Mn>fs which \i>n Hiuui'.+ttit and h*.t fumfanian carrud hftn-em the l*Jt 4AofM&' M TV tTiawichakata Indumt several nutuhfs .t nA.-m \,.H ffumbMt saw at Sola** . :'.'! " 36 TV Lake ir^nvi a7 TV tiamrs hke the lhn.ui the banks viwhidi thf L.iu <*vws thf seeds vfwhuJt thf reakhuy thf qx* H' muafu .* ths /. /-//.- frtirr^ iy s RIVERS. 299 that it would have been upset by any one rising imprudently from his seat, without warning the rowers to preserve its balance by leaning to the opposite side. We had suffered severely from the stings of insects, but had withstood the insalubrity of the climate ; we had passed without accident the numerous falls and bars that impede the navigation of the rivers, and often render it more dangerous than long voyages by sea. After all we had endured, I may be allowed to mention the satisfaction which we felt in having reached the tributaries of the Amazon." The Eio Negro, which flows into that river, was navigated downwards as far as San Carlos, then supposed to lie under the equator, but actually about 2° N. From thence the travellers retraced the river, passed from it into the Cassiquiare, and again entered the main channel of the Orinoco, three leagues below the mission of Esmeralda ; thus demonstrating a junction between the two great floods of the Amazon and Orinoco, which had been, in the year 1798, declared byBauche to be a geographical monstrosity. The bifurcation of the Orinoco takes place in the fol lowing manner : — The river, issuing from among the mountains, reaches the opening of a valley or depression which terminates at the Rio Negro. Here it divides into two branches, the smaller, or the Cassiquiare, turning off to the south, while the main stream continues its original direction — west-north-west. A reference to Humboldt's map, of which we give a translated copy, will render further explanation unnecessary. The preceding notices refer to what have been appropriately styled the " might rivers," and the " great rivers," none of which are to be found in Europe. Its noblest running waters belong to a third grade. " These," says Inglis, " I would designate the large rivers ; for great and large are not entirely synonymous ; and, to most minds, the term great river and large river, will present a distinct image. The lower we descend in the scale, the more numerous do we find the species. The continent of Europe abounds with examples of the third class — such as the Rhine, the Danube, the Rhone, the Elbe, the Tagus, the Ebro, and the Guadalquivir. The fourth class is still more numerous ; and of this class, which I would call considerable rivers, we may find examples at home. Father Thames takes the lead ; and the Severn, and perhaps the Trent, the Clyde, the Tweed, the Tyne, and the Tay, may be entitled to the same distinction. On the Continent, it would be easy to name a hundred such ; let me content myself with naming the Loire, the Meuse, the Saone, the Garonne, the Adige, and the Maine. Fifthly, come the small rivers. Multitudinous they are ; but as examples, I may name the Wye, the Dart, the Derwent, the Dee, the Aire, the Spey, the Ex, and a thousand such ; while on the conti nent, of the same class, may be mentioned the Gare, the Seine, the Reuss, or the Sambre. The word river can no longer be employed, for now come the family of streams — name less, except to those who live upon their banks : the rivulets follow ; and, lastly, we close the enumeration with rills." The small rivers, with the streams subordinate to them, are especially rife in countries where there is the vicinage of the sea, and high ele vations on the land. This renders them so abundant in such districts as the Greek pen insula. There, Alpine tracts of territory collect from the atmosphere the vapours of the contiguous sea, arrest the castellated glories of cloud-land, and awaken in the valleys and plains the refreshing music of the voice " of many waters." The commerce of kingdoms distinguishes not the rivers of this classic soil, but they are familiar with the charms of nature, add effect to the sublime and wild in its scenery, and clothe with heightened grace the soft and pastoral. Following the course of the Angitas up to its source, we come to one of the most picturesque sites in Macedonia, supposed to be the nymphaeum or grotto of Onocaris. Blocks of marble, rudely piled, as if tossed together by an earth quake, obstruct its entrance, which can only be passed in a crawling posture ; but these difficulties being overcome, a cave like a tejtple appears, from the farther end of which runs the limpid stream, flowing silently over a sand bed, but rippling when it escapes 300 PHYSICAL GEOGRAPHY. from the grotto. In a recess, there are some remains of ancient raasonrv below an aper ture, through which a mysterious light finds its way. " Pure element of waters ! whercsoe'er Thou dost forsake thy subterranean haunts, Green herbs, bright flowers, and berry-bearing plants, Rise into life, and in thy train appear." Upon the large circular valley-plain of Boeotia. the heights of Parnassus on the west, Helicon on the south, and Cithseron on the east, send down streams, covering the undulating surface of this Classic Land with a life-sustaining vegetation. The same physical causes — high lands and the contiguous sea — operate, in Judca as in Greece, to render it a well-watered country — a "land of brooks," according to its scripture designation. There are no considerable rivers, owing to the scanty extent of its hydrographical basins ; but the melting of the snow on the high mountains of Syria, and the periodical sound of an " abundance of rain," contribute to furnish an ample irri gation. Its principal stream — the Jordan — though only one of the fifth class, and not remarkable for picturesque beauty except in the upper part of its course, has a sacred and historic interest which will always strongly attract attention to it, while it exhibits a sin gular physical peculiarity. This is the depression of the valley, in which it flows, below the level of the Mediterranean, through the whole distance between the Sea of Tiberias and the Dead Sea ; and the great inclination of its descent from the one to the other, amounting at a mean to very nearly eighteen feet per mile. Hence the force of its cur rent, notwithstanding a comparatively small volume of water, and the few windings that mark its channel. Speaking of its appearance near the site of Jericho, Dr. Robinson states: " There was a still though very rapid current. We estimated the breadth of the RIVERS. 303 the tide flows out of the river, it pours forth its unshackled current with greater fury, and meeting at right angles with the ocean current that runs from Cape St. Eoque along the north-east coast of Brazil, the shock of these two bodies raises their waters into an embankment, upwards of a hundred feet in height. The roar of the clashing waves is heard for miles around, and the fishermen and mariners fly in terror from the scene till the strife is over, speedily to be renewed. In treating of the magnitude of rivers, some writers refer to the elevation of the range of mountains from which they descend ; and it is obviously true, that the greater the height of the mountains, the more extensive are their snows and glaciers, and the larger the supply of water furnished by springs and torrents. But the magnitude of a stream is more especially regulated by the extent of country which forms the declivities of its basin, though there is no invariable proportion here, for a small basin in a humid region will yield a greater quantity of water than one much more considerable in a different situation. High mountains, a humid climate, and a wide superficial drainage, are the three physical circumstances which lead to the accumulation of vast bodies of water, the magnitude of which will be proportionate to the degree in which these causes are in combined operation. Upon the surface of the New World, we have these causes acting with greater intensity than upon that of the Old, which explains the superior character of the streams of the western continent. The following table exhibits the extent of the hydrographical regions of the principal rivers of the globe, with the proportionate size of their basins : EIVBRS— LOCALITIES. Area of Basin in English Square Miles. Proportional Size of Basin. Humber, including Trent and Ouse, to Spurn Point,) the largest British river, J Po — Italy, 27 000 3 ASIA. Loire— France, Elbe — Germany, Rhine — Switzerland, Germany, Holland, Vistula — Russian Poland, Prussia, Dnieper — Southern Russia, .... Don — Southern Russia, Danube— Bavaria, Austrian Empire, Turkey, . Volga — Central Russia, Euphrates — Armenia, Mesopotamia, . 48,000 50,000 70,000 76,000 200,000 205,000 310,000 620,000 230,000 5 6i « 8 21 21* 64* 24 Indus — Northern India, . 410,000 416000 43 43i Hoang-ho — China, 710,000 750 000 74 78 800000 83J Lena Eastern Siberia, ..... 800,000 83J 1,040,000 109 Obi — Western Siberia, 1,250,000 131 AUSTRALIA. . . . AFRICA Murray — New South Wales, South Australia, Orange, or Gariep — South Africa, 480,000 ? 360,000 50 38 AMERICA .... Niger — Soudan, Western Africa, .... Nile — Abyssinia, Nubia, Egypt, Orinoco — New Granada, Venezuela, Araguay, or Tocantins — Brazil, Saskatchewan — British America, .... St. Lawrence— Canada, United States, Mackenzie — British America, .... 800,000 ? 1,425,000 ? 360,500 381,000 478,000 626,000 590,000 1,242,000 • 83J 149 33 40 60 55 61i 130 Mississippi-Missouri — Central North America, Amazon — Peru, Equador, Brazil, 1,333,000 2.275,000 139J 238 Elvers, according to their termination, may be grouped in two grand classes, the conti nental and the oceanic. The continental are those which have no communication at all with the ocean, but discharge their waters into completely insulated lakes, or lose them selves in sands and swamps. Thus the Volga, Kour, Terek, and Ural, terminate in the Caspian ; the Amou, or Jihoon (ancient Oxus), the Sir, or Sihoon (ancient Jaxartes), flow to Lake Aral ; and the Jordan finishes its course in the Dead Sea. On the lofty table lands of Mexico, Bolivia, and Central Asia, there are respectively the Rio Grande, Desaguadero, and Yarkand, which are entirely confined to those elevated regions, termi- 30 i PHYSICAL GEOGRAPHY. nating in lakes, marshes, or sands. This is the case also with many streams in the interior of Africa. On the contrary, the oceanic rivers either flow direct into the main ocean, or into seas, bays, and gulfs, directly communicating with it. This class embraces the great majority, which are referred to their respective oceanic basins in the annexed table. I— SYSTEM OP THE ARCTIC OCEAN. ElVERS. RISE. TERMINATION. Length in English Miles. Lena. Heights near Irkutsk, E. Siberia. Asiatic Arctic Ocean. 2,770 Olensk. Eastern Siberia. Ditto. 1,150 Yenisei. Mongolian Desert, Chinese Empire. Ditto. 3,230 Obi. South slope of the Altai Mountains. Ditto, Gulf of Obi. 2,670 Petchora. Ural Mountains. European Arctic Ocean. 695 Dwina. Heights of Vologda. Ditto, White Sea. 1,000 Mackenzie. West side of the Rocky Mountains. American Arctic Ocean. 2,440 II.— SYSTEM OP THE ATLANTIC OCEAN. Humber (Trent Branch). Moorlands of North Staffordshire. German Ocean, or North Sea. 171 Vistula. Austrian Silesia. Baltic, Gulf of Dantzic. 600 Elbe. Elb-brunnen, Bohemia. North Sea. 790 Rhine. Rhetian Alps. Ditto. 695 Loire. Mont Gerbier-le-Joux, Cevennes Mountains. Bay of Biscay. 600 Rhone. Glacier of Mont Furca, Switzerland. Gulf of Lyons, Mediterranean. C48 Po. Monte Viso, Cottian Alps. Adriatic Sea. 500 Danube. Black Forest, Swabia. Black Sea. 1,725 Dnieper. Alaunian Hills, government of Smolensk. Ditto. 1,240 Don. Lake Ivanhof, government of Tula. Sea of Azof. 1,110 Nile. Unknown, but South of the Equator. Mediterranean. :i,GOO ? Senegal. Near Teembo, N. E. of Sierra Leone. North Atlantic. 1,140 Niger. Base of Mount Loura, Soudan. Ditto, Bight of Benin. 3,000 ? Orange, or Gariep. Mountains N. W. of Port Natal. South Atlantic. 1,000? Saskatchewan. West slope of Rocky Mountains. Hudson's Bay. 1,920 St. Lawrence. West of Lake Superior. North Atlantic. 2,070 Mississippi- Missouri. West slope of Rocky Mountains. Gulf of Mexico. 4,100 Rio-del-Norte. Sierra Verde, New Mexico. Ditto. 1,400 Magdaleua. Andes of New Granada. Caribbean Sea. 1,050 Orinoco. Mountains of Spanish Guiana. North Atlantic. 1,500 Amazon. East slope of the Andes, in Peru. South Atlantic. 3,550 Araguay or Tocantins. Southern Brazil. Ditto. 1,400 St. Francisco. Sierra dos Vertentes, Brazil. Ditto. 1,000 La Plata. South- Western Brazil. Ditto. 2,210 m.— SYSTEM OF THE PACIFIC OCEAN. Amour. Frontier of Russian and Chinese Empires. Sea of Okhotsk. 2,740 Hoang-ho. Koulkoun Mountains, Chinese Empire. Yellow £ea. ? Yang-tse-kiari'j. Ditto. Ditto. | Si-kiang. Interior of China Proper. Gulf of Canton. 1,110 Meinam. Interior of Siam. China Sea. 1,080 Cambodia. Thibet. Ditto. 2,000 ? Columbia. Rocky Mountains. North Pacific. 1,570 ? Colorado. Unexplored. Ditto, Gulf of California. 900? IV.-SYSTEM OF THE INDIAN OCEAN. Euphrates. Highlands of Armenia. Arabian Sea. 1,720 Indus. Himalaya Mountains. Ditto. 2,000 ? Ganges. Glacier in Himalaya Mountains. Bengal Sea. 1,000 Brahmapootra. North Slope of Himalaya Mountains. Ditto. 2,000 ? Irawaddy. Mountains eastward of Assam. Ditto. 2,000 ? Murray. Coast Chain of New South Wales. Encounter Bay. 1,000 ? It will be seen from the table, that the Atlantic receives a much larger proportion of river-water than any other ocean. Of twenty-one rivers, previously enumerated, which drain areas of 300,000 square miles, and upwards, eleven pour their waters into its bed. The first place among the rivers of the globe is due to the Amazon, if not for the length of its course, yet for the volume of its waters. It traverses the equatorial regions of South America, chiefly in a direction from west to east, and has its embouchure nearly under the equator. Its mouth was discovered in the year 1500 by Pinzon, one of the captains who sailed with Columbus on his first voyage ; and thirty-nine years afterwards, RIVERS. 305 the stream was traced downward from Peru by Francisco Orellana, whose name was given to the river by his countrymen, to preserve the memory of his bold enterprise. But the Spaniard's report of having met with armed women on its banks, deprived him of the honour, for it originated the common title of the river of the Amazons. Its prin cipal affluents rival the largest rivers of the Eastern continent, as appears from the fol lowing statement of their supposed lengths : — Miles. Miles. Ucayali - . 1350 Yutai - . 750 Jaura .... 750 Madeira - ... 1800 Topayos - 1 000 Xingu - - 1080 Napo - - 80O Rio Negro .... 140O The width of the Amazon averages from one to two miles in the upper parts of its course, but towards its termination its opposite banks are seen with difficulty, and it widens to upwards of a hundred miles, which is about its breadth upon joining the Atlantic. For two thousand miles in a direct line from the ocean, the river is navigable by vessels of any burden, for at the confluence of the Tunguragua and Ucayali, where the Amazon, properly so called, commences, no bottom was found, in March 1836, with a line of 35 fathoms, or 210 feet. The tide rushes up its channel with immense violence at the period of the full moon, in two, three, and sometimes four successive waves, each presenting a perpendicular front of from ten to fifteen feet. When the tide ebbs in the rainy season, the liberated waters of the river rush out of their channel with tremendous force, and create a current in the ocean, which is perceptible five hundred miles from its mouth. It is difficult to sound the river, owing to the rapidity of its current, which runs commonly at the rate of from three to four miles an hour, — a momentum not arising from the in clination of its bed, the fall of which is very gradual, but from the immense quantity of water which descends in it. The climate of its basin is perhaps the most humid to which any country is subject. The quantity of rain which annually descends upon this region has not been ascertained with precision ; but taking that at the town of Maranhao as a sample, which is not less than two hundred inches, the amount of rain poured upon the district of the Amazon every year must be prodigious. The heat also is excessive through the whole year, the thermometer in the shade frequently rising to 106° when the sun is near the line, a degree of heat not much inferior to that experienced in the Sahara ; and as moisture and heat are the most efficient agents in promoting vegetation, hence the luxuriance and energy of vegetable life in the fertile soil on the banks of the river, where the noblest woodland scenery in the world is to be found. Notwithstanding the rapid current of the Amazon, its navigation is easy to vessels both descending and ascending its course, the ascent being facilitated by the far-penetrating tide of the Atlantic, assisted by the wind, which is always blowing from the east, a direction contrary to that of the stream. But the effect of the presence and absence of civilisation is nowhere more strikingly exhibited than on the waters of the South American river, and those of its rivals, the Mississippi, and the Yang-tse-Kiang of the Chinese empire. The vessels that annually appear upon the surface of the Amazon are, probably, not more than those which monthly navigate the Mississippi, or daily pass along the course of the Yang-tse-Kiang. At the head of rivers, classed according to their length, the Mississippi is to be placed, taking the Missouri branch, which ought to be the name of the united stream, not only on account of its longer course, but because it brings down a greater body of water, and imparts its turbid character to its rival. Geographers have, however, given the former name to the joint rivers, the "Father of Waters," according to its Indian signification, which may be aptly applied to the great central valley of North America, furnishing the 306 PHYSICAL GEOGRAPHY. following streams, which unite in the channel of the Lower Mississippi, and pour down through it into the Gulf of Mexico : — St. Peter's - Penaca, or Turkey - Iowa Chacaguar Des-moines - St. Croix Chippewa Wisconsin Rock River - Illinois Salt - Missouri Yellowstone Little Missouri - Shienne - Quicourt Platte - Kansas - Osage Gasconade Jacques - Sioux Grand - Chariton Miles. 500 200 350 200 600 300 300 GOO 450 500 250 3300 1000 3OO 3OO 500 1200 800 500 30O 600 500 500 200 Kaskaskia Maramec St. Francis - White Arkansas Canadian Neosho - Red River - Washita - Ohio- Alleghany Monongahela Kanawha Kentucky Green Cumberland Tennessee Muskingum Scioto Waybash White River Hatchy Yazoo Big Black - Miles. 300 200 450 600 2500 1000 800 2000 800 1250 350 300 450 360 3OO 600 1500 200 200 550 200 200 300 200 The most beautiful tributary of the Mississippi is the Ohio, the Belle riviere of the early French settlers, the only large river it receives from the east. No stream rolls for the same distance so uniformly and peacefully ; its banks are adorned with the largest sycamores, its waters clear, and studded with islands covered with the finest trees. All the other great tributaries flow from the west, its confluence with the Missouri, which enters it like a conqueror, and carries its white waves to the opposite shore, presenting one of the most extraordinary views in the world. The country around these vast watercourses is of the most varied description, alternately exhibiting wild rice lakes and swamps, limestone bluffs and craggy hills, deep pine forests and beautiful prairies, the prairies showing an almost perfect level, in summer covered with a luxuriant growth of grass and flowers, without a tree or a bush, the only tenants of which are elks and buffaloes, bears and deer, and the savages that pursue them. The bluffs of the Mississippi are for the most part perpendicular masses of limestone, often shooting up into towers and pinnacles, presenting at a distance the aspect of the battlements and turrets of an ancient city. In the season of inundation below the mouth of the Ohio, the river presents a very striking spectacle. It sweeps along in curves or sections of circles, from six to twelve miles in extent, measured from point to point, and not far from the medial width of a mile. On a calm spring morning, and under a bright sun, this sheet of water shines like a mass of burnished silver, its edges being distinctly marked by a magnificent outline of cotton wood trees, at this time of the year of the brightest verdure, among which those brilliant birds of the country, the black and red bird, and the blue jay, flit to and fro, or wheel their flight over them, forming a scene which has all of grandeur or beauty that nature can furnish, to soothe or enrapture the beholder. The curvilinear course of the Mississippi is one of its most striking peculiarities. It meanders in uniform bends, which, in many instances, are described with a precision equal to that obtained by the point of a compass. The river sweeps round the half of a circle, and is then precipitated in KIVEKS. 307 a diagonal direction across its own channel, to another curve of the same regularity upon the opposite shore. Instead of calculating distances by miles or leagues, the boatmen and Indians estimate their progress by the number of bends which they have passed. This conformation, which distinguishes most of the streams of the Mississippi valley, must have transpired under the operation of some law, but hitherto no solution of the problem has been given which is quite satisfactory. Geological appearances indicate that this stream, like the Orinoco, had in former ages a much broader volume, though a shorter course ; that, in fact, it once found its estuary not far below the present mouth of the Ohio, the alluvial country now stretching from thence to the south, near a thousand miles, being then an arm of the sea. " No thinking mind," says Flint, " can contemplate this mighty and resistless wave, sweeping its proud course from point to point, curving round its bends through the dark forests, without a feeling of sublimity. The hundred shores, laved by its waters ; the long course of its tributaries, some of which are already the abodes of cultivation, and others pursuing an immense course without a solitary dwelling of civilised man on their banks ; the numerous tribes of savages that now roam on its borders ; the alTecting and imperishable traces of generations that are gone, leaving no other memorial of their existence, or materials for their history, than their tombs, that rise at frequent intervals along its banks ; the dim, but glorious anticipations of the future; — these are subjects of contemplation that cannot but associate themselves with the view of this river." Though far inferior to these streams of the western world, in point of length and volume, the Nile of the ancient continent may be placed at the head of remarkable rivers. One of its chief peculiarities is the solitary grandeur of its flow, for not a single affluent enters it, from the junction of the Tacazze to the sea, a distance of 1500 miles, a circumstance without a parallel in the physical condition of rivers. Another of its striking features is its long course through a desert, dry, barren, and hideous, depositing by its annual inundation, the richest soil on those portions of it which lie contiguous to its banks ; and hence has originated the apt comparison of its career to the path of a good man amidst an evil generation. Egypt would be completely sterile, were it not for the periodical overflow of its only stream, which both covers a large part of its surface with a layer of alluvion, and imparts to it the requisite moisture. " Rich king of floods ! o'erflows the swelling Nile — glad to quit The joyless desert, down the Nubian rocks From thund'ring steep to steep, he pours his urn, , And Egypt joys beneath the spreading wave." It requires the river to attain a medium rise in order to benefit the country ; too little, involving scarcity and famine ; too much, compromising the safety of the people and their dwellings. Wilkinson calls a rise of 19 cubits tolerable ; 20 good; 21 sufficient, while a rise of 22 cubits is abundant enough to fill every canal ; and a rise of 24 cubits would overwhelm and ruin the villages. A cubit is rather more than 21 inches, so that in order fully to meet the wants of the country, a perpendicular rise of 38 feet is necessary. The Nile is also distinguished among rivers for the pleasant taste and salubrity of its waters, when not in flood ; properties highly extolled by the ancients, and acknowledged to belong to it by modern travellers. It is a common saying with the Egyptians, that if Mahomet had tasted of its stream, he would have sought a terrestrial immortality in order to enjoy it for ever. The physical circumstances of the river easily account for the possession of this attribute. The air above is pure and serene. .But little rain falls upon the country through which the greater part of its course is prosecuted, and no snow or hail. Hence there is little drainage into it from the surrounding land, and its waters are kept free 308 PHYSICAL GEOGRAPHY. from any noxious taint derived from earths and minerals, except from those in its immediate channel. The same property of being remarkably pure and salutary, is ascribed by Herodotus to one of the Susianic rivers, of which alone, according to tradition, none but the kings of Persia drank. " There Susa, by Choaspes' amber stream, The drink of none but kings." The "Susianic streams, along with the Nile, may not improperly be styled the oldest rivers of the globe, because of their place in its most ancient traditions and histories; and however subordinate to the gigantic currents of the western hemisphere, those of the eastern in general present higher points of interest, in their long known identification with the destinies of mankind. If not the actual birth-place of man, the great plains on the banks of the Tigris and the Euphrates were the abode of the founders of the diluvian race. There, the two greatest cities of the ancient world, Nineveh and Babylon, rose into magnificence. There, a supernatural finger traced the doom of the latter upon the palace wall of its trembling monarch, while an exiled Jew, in the majesty of inspiration, gave him the interpretation of the mystic writing. There, too, in later ages, the same neighbourhood witnessed the catastrophe of Cunaxa, and the bold bearing of the indomitable ten thousand — the splendid empire of the Hedes and Persians overthrown by the Macedonian on the field of Arbela — the defeat and death of Crassus — the retreat of Mark Antony — the fall of the apostate Julian — and the short-lived glory of Bagdad. How different the associations connected with the Arkansas and the Osage to those of the Euphrates and Tigris ! ancient, remains CHAPTER LAKES. ARGE or small collections of water, fresh or saline, and surrounded by land, are termed lakes, and have an aspect, upon the face of the continents, similar to that of islands in the ocean. They differ from re servoirs in not being artificial, but natural, forma tions ; and from lagoons, which are simply the overflowings of rivers in the season of flood, or portions of the sea which have encroached upon the land, and been separated from the parent deep by the gradual accumulation of banks of sand, or barriers of earthy material. They differ also from pools, which are mere collections of rain-water in hollow places, generally dried up in periods of drought ; whereas true lakes are formed in va cuities, either by streams flowing into them from the surface, or by springs gushing up from their bed. These fluvial formations may be referred to a great variety of causes, the action of some being of and others of comparatively modern date. It is supposed that many lakes are the of the universal ocean which once covered the earth, the waters of which have LAKES. 309 retained their saltness where there was no outlet, but have lost it in other cases, by receiving constant supplies of fresh water through rivers, and continually letting off the salt through outlets. Owing to the subsidence of the soil, or the falling in of the roof of a subterranean cavity, in periods of internal convulsion, the superficial waters of the surrounding country have been drained into the hollows thus created, and aqueous expan sions have been formed. Others have been caused by land avalanches, and the projec tion of lava currents across streams, occurring within the memory of man ; but the great majority of lakes date their existence from the time when the crust of the globe received its present general outline, and were produced by the waters encountering those inequali ties of the surface which mark its configuration. A river, impeded in its course by mountainous elevations, either effects its passage by winding about their lateral extre mities ; or, if enclosed on all sides, it forms a lake, which, rising to a level with some gorge in the interposing barrier, pours its surplus waters through it. A river, also, meeting with an abrupt and broad depression in the plain or valley which it traverses, fills the basin, and forms itself into a lake, the superfluous waters flowing away at the opposite extremity. There is a striking, though in one respect insensible, relation sub sisting between rivers and considerable lakes. The former visibly feed the latter ; and the latter no less certainly feed the former, though in a manner that is not so apparent to our senses. By a process of evaporation, the lakes are continually giving off a portion of their mass, which rises in the atmosphere in the form of vapour, and again visits the earth in the form of rain, originating the springs and rills, which unite in rivers, flow into the lakes, and replace their waste. There is no machinery of nature more compli cated, beautiful, nicely adjusted, and benign in its results than this; for hereby the earth is preserved either from perpetual barrenness, through want of moisture ; or from submer gence, through the ocean overflowing its present bounds. The lakes of primary regions are distinguished by the wild and romantic character of their scenery, rugged precipices and dark forests usually lining their shores, and rocky Loch Katrine. 310 PHYSICAL GEOGRAPHY. The Kaudal Steig, Switzerland. islands rising out of their bosom, which add greatly to the effect of their appearance. They are often small, generally transparent, placid, and solitary ; and, being altogether without artificial embellishment, the naked grandeur of the engirdling cliffs renders them far more impressive than those which are enriched with towns, and ornamented with villas, like the lakes of Northern Italy. In Scotland, the Scandinavian peninsula, the Alps, and Andes, many sheets of water are found set like gems among the mountains, seldom visited except by the flocks of wild-fowl which float undisturbed upon their breast, where the silence is rarely broken but by their cry, and the splash of the rills descending into their basin. At the head of the river Kandal, in the Swiss canton of Berne, there is a lake of this kind, formed by the aggregated waters of numerous springs, which pour their torrents from the neighbouring mountains. The lakes of secondary regions are charac terised by the softer beauties of the landscape, though not without bold and striking features. The banks are gently undulating, and usually adorned by cultivation. Such is the general aspect of the Italian, English, and Irish lakes ; those of Killarney, amid the mountains of Kerry, in the sister island, being reinai'kable for their picturesqueness. They are three in number, mutually connected, but varying to some extent in their scenery. The upper lake lies in a hollow formed by some of the loftiest of the Irish mountains, so that its character is in the highest degree magnificent and sublime ; but softness and beauty are the prevailing attributes of the two others. Their banks exhibit gentle swells covered with the freshest verdure, with lovely islands in their waters, upon which are trees worthy of a primeval forest ; and it is in this contrast of the mild and graceful with the wild and rugged, that the- chief charm of the Killarney lakes consists. Those of alluvial districts have few external recommendations. Their shores are usually low and level, and their waters are often stagnant, in many cases yielding unhealthy exhalations from the marshes which form their borders. The South Baltic coast, that about the mouths of the Nile and Mississippi, and the plains around the Caspian, abound with these lakes, which commonly partake of the saltness of the contiguous seas. England presents few examples of lakes, and none of any considerable size, though Winandermere, the largest, exhibits, along with Ulswater, Derwent, and Coniston- water, many natural beauties. They have indeed been preferred by some of our countrymen to the Swiss lakes, on account of being ornamented with woody islands, in LAKES. 311 which those of Savoy and Switzerland are deficient ; and perhaps, apart from this, a physical cause may be found for the preference, in the case of passing visitors, independent of all national partiality. Owing to the greater transparency of the atmosphere in Switzerland, the giant mountains east of the Lake of Geneva do not appear at first more elevated than the comparative dwarfs at the head of Ulswater, to an eye unaccustomed to so clear a medium. Hence, the first impressions of the Alps are commonly the feeblest, a due appreciation of their magnitude being the fruit of acquaintance ; whereas, a denser atmosphere gives to our scenery fictitious features, which acquaintanceship corrects. In Scotland the lakes are more numerous and important, the superficial dimensions of each of the following twenty-four exceeding the area of Winandermere. Sq. Miles. Sq. Miles. Loch Lomond - • 45 Loch Ericht - - 10 Awe - 30 Earn Ness - - 30 Naver - 9 Shin - - 25 Stennis - - 8 Maree - - - - 24 Rannoch - - 8 Tay - - - - 20 Leven - - 7 Arkeig - - 18 Fuir - G Shiel - 16 Lydoch - - 6 Lochy - - 15 Ken - 6 Laggau - - 12 Loyal - - G Morier - - 12 Glas Fannich - - 10 Katterin - - 5 la Ireland they are still more considerable, Lough Neagh, in the centre of Ulster, being the largest lake in the United Kingdom, more than three times the size of Loch Lomond, having a superficial extent of nearly 100,000 acres. The total superficial area of the Irish Lakes is supposed to amount to 455,399 imperial acres. The annexed table gives the extent of the principal European lakes. Sq. Miles. - 6330 - 3280 Ladoga, Russia Onega, ditto Wener, Sweden Saimas, Finland Peipouss, Russia Wetter, Sweden Malar, ditto Enara, Lapland Kuopio, Finland Geneva, Switzerland - Constance, ditto 2136 1602 839 839 763 656 610 336 290 Ilmen, Russia - Lexa, ditto Ulea, Finland - Garda, Italy - Maggiore, ditto Nesi, Finland - Balaton, Hungary Neufchatel, Switzerland Lake of the Four Cantons, ditto Zurich, ditto - Bielo, Osero, Russia Sq. Miles. 275 229 229 183 152 152 152 114 99 76 53 The largest lake in the world, the Caspian, is geographically situated both in Europe and Asia, but is commonly classed with the physical features of the latter country, and styled a sea from its size and saltness. Measured according to its curvilinear shape, in the middle of its breadth, it exceeds 900 miles in length, with an average width of 200, and has an area of nearly 160,000 square miles. The next in extent, that of Aral, has, with the Caspian, received the denomination of an inland sea, and is nearly a fourth part of its size. The Lake Baikal, in Siberia, has a computed area of 20,000 square miles, and, both in central and western Asia, there are large expanses of nearly equal extent. In Africa, lagoons occur along the coasts ; small briny pools, also, are common in the deserts ; but the interior is a great mass of solid land, seldom broken by either rivers or lakes. The chief of the latter, and the best known, is that of Dembia, nearly centrical in Abyssinia, measuring, in Brace's map, 65 miles in its greatest length. The Tchad, in Central Africa, is much larger, but has extensive shallows, and varies vastly in its volume, according 312 PHYSICAL GEOGRAPHY. to the season. This is the case also with the Ngami, in Southern Africa, the first of the discoveries of the intrepid Dr. Livingstone. The northern part of the western world is pre eminently the country of lakes, presenting the largest masses of fresh water to be found upon the surface of the globe. The following statement shows the area of the principal : — Sq. Miles. Sq. Miles. Lake Superior - - 40,OOO Huron - 25,000 Michigan - - 25,000 Erie - 11,000 Ontario .... 10,000 Winnipeg .... 9,000 Athabasca - . 3,000 Great Slave Lake - - - 12,000 Great Bear Lake - - 8,000 Champlain - - 500 In South America, the Lake of Titicaca, in Upper Peru, covers a surface of about 4000 square miles ; and immense swampy plains and lagoons are common along the course of the rivers. Lakes are sometimes considered under the two divisions of fresh and salt water, but there are many occupying intermediate stations with reference to these extremes. We shall follow another arrangement of them, into four classes, which will more fully embrace their physical conditions, and then notice some remarkable phenomena, by which several are distinguished. 1. There is a class which have no apparent affluents or outlets. They are fed chiefly by subaqueous springs, and occur frequently in hollows, which have the appearance of extinct volcanic craters. They are generally small, but of more stable character than the larger sheets of water formed by rivers. Not receiving any great superficial current, they are not subject to those changes of their depth and outline, which take place in the lakes with affluents, through deposition of the mud and sand brought into them by turbid torrents. Collections of water of a similar kind abound in the great steppes of northern and western Asia. They are called lakes, but are perhaps more properly pools, being formed of accumulated rains and melted snow, which are largely, and in some cases entirely, evaporated by the summer heat, though several have a circumference of from ten to twelve miles, and a depth of six or seven feet. Their waters are commonly saline, and what is most remarkable, and hitherto unexplained, sheets of fresh water are found in their immediate vicinity. The most considerable example of this class is the Lake of Tuzla, wliich lies northward of the great range of Taurus, on the high central plateau of the Lesser Asia. Though narrow, it extends fifty miles in length, and is so extremely salt, that no fish or aquatic animal can live in it. Even the wild fowls are afraid to venture upon its waters, for by so doing their wings become stiff with a thick coating of salt, and any substance thrown into them speedily receives a saline incrustation. Strabo, the geographer of antiquity, a native of the peninsula, was personally acquainted with this lake, and mentions these circumstances, the accuracy of which, modern travel has confirmed. The Sultan Murad IV. made a causeway across it, upon the occasion of marching his army to the attack of Bagdad, for, owing to excessive evaporation during the summer and autumn heats, the lake is extremely shallow. The remains of this causeway are now almost concealed by a saline encasement, and a thick crust of solid salt covers the bed of the lake. 2. Another class have outlets, but no apparent affluents. These lakes usually occupy a high elevation above the level of the sea, and derive their supplies from subterranean springs. One on Monte Rotondo, in the island of Corsica, is at the height of 9000 feet. They are not inconsiderable in number, and are frequently the sources of important rivers. The course of the great Volga may be traced up to a lake of this kind, but which is only slightly elevated above the sea-level. 3. A third class receive affluents, but have no outlets. Lakes of this description are exceedingly rare, but they are the most peculiar of all. That of Celano in Italy, the LAKES. 313 ancient Fucinus, exhibits a superficial ex tent of 100 square miles, and has no natural outlet for its waters through the hills by which it is surrounded. Owing to its rise in former times, an immense tract of excel lent land was lost, and the Roman senate was petitioned to drain it, a scheme which Julius Caesar is said to have contemplated. For effecting this purpose a tunnel three miles long, through one of its mountain boundaries, was formed by the Emperor Claudius; and the younger Pliny relates the barbarous ceremony of its opening. During the space of eleven years, thirty thousand men were employed in digging the passage, and when everything was ready for letting off the water, a naval spectacle was exhibited upon it. A great number of con demned criminals were ranged in separate fleets, obliged to engage in earnest, and to destroy one another for the entertainment of the court, and the multitude of spectators who covered the hills. A line of well- armed vessels and rafts, loaded with soldiers, surrounded the scene of action, in order to prevent any of the victims from escaping. Pliny states, however, that when this savage diversion was ended, and the operations for opening the tunnel commenced, the emperor was very near being swept away and drowned, by the sudden rush of the waters towards the vent. The tunnel was speedily choked up, and the Celano lake rose so much as to cover ten thousand acres of fertile soil, when it was again re-opened, and other hydraulic means adopted to keep the waters to a low level. Lakes of this description, without any outward current, though continually receiving large streams, are principally found in Asia, and are for the most part salt. Such is the great Lake of Urumiah on the Persian frontier, which, according to Colonel Kinneir, is three Cascade in Mount Taurus. 314 PHYSICAL GEOGRAPHY. hundred miles in circumference, and is land-locked amid the picturesque mountains and valleys of Azerbijan. Though constantly fed by numerous currents, it has no outlet ; yet there is no increase of its waters, but a gradual diminution, the waste through evapora tion being greater than the supply. The lake is intensely salt, as appears from the depo sitions left upon the beach. For some distance from the brink, a perfect pavement of the solid mineral may be seen under the shallows. A village is pointed out as having once overhung its waters, which is now separated from them by a strand covered with salt, a quarter of a mile broad. Beyond a chain of hills to the north-west lies another example, the Lake Van of Armenia, so celebrated for its beauty by the eastern writers, both in prose and verse. It occupies the bottom of a volcanic amphitheatre, is upwards of 240 miles in circumference, and receives the waters of eight rivers without sending off any stream. By far the most remarkable instances of this class of lakes are the Caspian, the Sea. of Aral, and the Dead Sea. The majestic volume of the Volga pours into the former, with the Ural, the Kur, and the Aras; yet, notwithstanding these great constant accessions, the Caspian dispenses no surplus waters through any outlet into the adjacent districts. It was once deemed a per plexing problem, how the contributions of its rivers were disposed of ; but the evaporation from so vast an expanse during the heat of summer must be enormous, fully adequate not only to prevent any permanent rise of its level, but gradually to diminish it. The sea of Aral likewise, to the eastward, exhibits the same peculiarity. It received the Jaxartes and Oxus of the ancient geographers, now the Sihoun and Amou, but no stream issues from its banks. Both these bodies of water are salt, and abound with marine productions. All the varieties of sea animals are common to them that are found in the Black Sea, except those transient visitors which arrive in the latter for the purpose of spawning ; and hence it has been conceived probable that both were once connected, forming a branch of the main ocean — an extension of the Euxine. The separation of the three, if ever they were united, may have arisen from the depo sition of the alluvial conveyed in the course of ages by the Volga and the Don, together with the subterranean action of elastic fluids which belong to this volcanic territory. The Dead Sea, in the south of Palestine, called also by the Latin geographers Lacus Asphaltites, and by the Arabs Bahr Lout, or Lot's Sea, though very insignificant in size, LAKES. 315 when compared with the former, has greater historical and physical interest. It receives that venerated stream, the Jordan, and flows over the presumed site of judgment -stricken cities, while its waters have a peculiar character, owing to their holding salts in excess. The general breadth of the lake, which is very uniform, is estimated by a recent and careful survey at about nine geographical miles, and the length at thirty-nine ; but the length appears to vary two or three miles in different years, or seasons of the year, according as the water extends more or less upon the flats at its southern extremity. During the rainy season, the influx derived from the Jordan and other streams is suf ficiently copious to raise the level ten or fifteen feet, which is gradually lowered by evaporation under the burning heat of an unclouded sun in summer and autumn. Irby and Mangles speak of observing the effect of the evaporation arising from it, in broad transparent columns of vapour, not unlike water-spouts in appearance, but very much larger. The lake lies in a deep cauldron, surrounded by lofty cliffs of naked limestone rock, the western range running up to the height of 1500 feet above the water, and the eastern to 2500. Sterility and death-like solitude prevail upon its shores, nor is it sur prising, considering its dreary aspect, the tremendous catastrophe of the cities once associated with it, and the nature of its waters, that such wild stories should have been so long current respecting this spot. Josephus, after speaking of the conflagration of the plain, remarks, that " there are still to be seen ashes re-produced in the fruits ; which, indeed, resemble edible fruits in colour, but on being plucked with the hands are dis solved into smoke and ashes." These are the far-famed apples " which grew Near that bituminous lake where Sodom stood," but which, stripped of the marvellous, are the 'Osher of the Arabs. This fruit externally resembles an appls or orange, but is filled chiefly with air, and bursts upon pressure. So far, however, from being peculiar to this region, it is found in great abundance in the Arabian peninsula, and along the valley of the Nile. In July, 1835, the Dead Sea was surveyed for the first time in a boat by Mr. Costigan, an Irishman, with a Maltese sailor as his servant, but who died soon after completing its tour. Mr. Stephens was informed by the servant, whom he found at Beyrout, that they had moved in a zig-zag direction, crossing the lake several times ; that every day they sounded frequently with a line of 175 brachia, each about 6 feet ; that they found the bottom rocky, and of very unequal depth, sometimes ranging 30, 40, 80, and 20 brachia, all within a few boats' length ; that sometimes the lead brought up sand, like that of the neighbouring mountains ; that they failed but once to find the bottom, and in that place there were large bubbles all around for thirty paces, rising probably from a spring ; that in four different places they found ruins, and could clearly distinguish large hewn stones, which seemed to have been used for buildings ; that at the south end of the lake a long tongue of high land projects into the water, and is composed of solid salt, which has at a distance the appearance of an island, the extremity being higher than the isthmus. The lake was again surveyed in a boat in March, 1837, by Messrs. Moore and Beke, who found its depth in some places 1800 feet. The aspect of the Mare Mortuum — the deep mountain ravine in which it rolls — the wilderness around — the silence, solitude, and infertility of the district — to gether with the remembrance of ancient disaster, make a deep impression upon the mind of the visitor, and explain the tales of the ignorant and enthusiastic pilgrims of a former age, who transformed the howling of the wind upon its surface into the cry of guilty spirits haunting its recesses. " The view of this evening," says Dr. Robinson, ' from our lofty encampment was most romantic. The whole Dead Sea lay before us. The full moon rose in splendour over the eastern mountains, and poured a flood of silvery 316 PHYSICAL GEOGRAPHY. light into the deep, dark chasm below, illuminating the calm surface of the sluggish waters. All was still as the silence of the grave. Our Arabs were sleeping round us on the ground ; only the tall pensive figure of the sheikh was seen sitting before the door of our tent, his eyes fixed intently upon us as we wrote." The waters of the Dead Sea are intolerably salt, bitter and nauseous to the taste, so pungent that the eyes smart severely after bathing in them, and extremely buoyant. " Two of us," says the traveller just quoted, " bathed in the sea ; and although I could never swim before, either in fresh or salt water, yet here I could sit, lie, or swim in the water, without difficulty." The following are the analyses of Dr. Marcet in 1807 ; of Professor Gmelin of Tubingen in 1826 ; and of Dr. Apjohn of Dublin in 1839. The water analysed by the latter was taken from a point just below the mouth of the Jordan, after the rainy season, and hence the smaller proportion of salts, and the less specific gravity, presented by his analysis. MAKCKT. «p* „*»». Boiling point. 221° Fah. Specific gravity .... Muriate of lime (chloride of calcium) magnesia (chloride of magnesium) soda (chloride of sodium) Sulphate of liine .... Water 1-211 Specific gravity Chloride of calcium magnesium Bromide of magnesium Chloride of potassium sodium manganese aluminum ammonium Sulphate of lime Water 1-212 1-153 3-020 10-240 10-360 0-054 3-2141 - 11-7734 - 0-4393 1-6738 - 7-0777 - 0-2117 0-0896 0-0075 0-0527 2-438 7-370 0-201 0-852 7-839 0-005 24-580 - 75-420 100 0-075 24-5398 - 75-4602 18-780 81-220 100 JOO There appears to be no animal or vegetable life in this supersalt sea, and the water-fowl are not attracted to its surface, owing to the absence of their customary food. " I dis mounted," says Seitzen, " and followed for a time the shore of the sea, to look for conchylia and sea-plants, but found none of either. And as fish live upon these, it might naturally be expected that no tenants of the waters would exist here ; and this is con firmed by the experience of all whom I have inquired of, and who could know about it. Snails and muscles I have not found in the lake ; some that I picked up on the shore were land snails." It is not improbable, however, that the Jordan, when swollen by the rains, may carry down fish into the lake, or they may voluntarily forsake the river- current ; but, as the naturalist Schubert remarks, " they soon pay for this love of wandering with their lives;" and hence small dead fishes are often picked up, which the waves have thrown upon the strand. The most remarkable of all the characteristics of the Mare Mortuum, is the depression of its level below that of the Mediterranean. There is no doubt respecting this fact, though estimates vary as the depth of the depression. From several observations on the temperature of boiling water, and by the barometer, Messrs. Moore and Beke inferred its surface to be 500 feet below the level of the ocean. Professor Schubert concluded it to be 600 feet ; but MM. Russegger and Bertou, in 1838, made the depression extend to the enormous amount of 1400 feet. The preceding measurements were barometrical ; but Lieutenant Symonds of the royal engineers has since surveyed the country inter vening between the two seas, and trigonometrically ascertained the level of the Dead Sea to be 1 337 feet below that of the Mediterranean. He proceeded from level to level by two different routes, and the results of each differ by merely an insignificant fraction, so that the question may now be said to be decided with exactness. A similar extraordinary circumstance characterises the Caspian and the Sea of Aral, and extends far into the LAKES. 317 interior of the continent, stretching northward to Orenberg on the Ural river, which is 500 versts, or about 335 miles, in a direct line from the shores of the Caspian. The surface of the latter has been found, by levelling across the isthmus, to be about 81 feet below that of the Black Sea. Humboldt considers the depression of this part of the continent to have an intimate connexion with the upheaving of the Caucasian mountains, of the elevated plain of Persia, and perhaps, more to the eastward, with the elevation of the great mass of land which is designated by the vague and incorrect name of the central plain of Asia. These are the more recondite speculations of geology, in favour of which a strong probability pleads. In the desert east of the gulf of Tajura, at the mouth of the Red Sea, one of the hottest and most detestable corners of the globe, a lake has recently become known to European geographers, the Bahr Assal, which is marked by the feature we are noticing. It is about six or seven miles long, and partially fills a deep hollow in a country of volcanic formation, being 570 feet below the level of the neighbouring sea, from which it is divided by a belt about six miles across. The waters are extremely salt, and are constantly receding by evaporation under the action of the intense heat, for when the British mission to Shoa had a day's bivouac in this terrestrial pandemonium, the mercury in the thermometer stood at 126°. The depression of the level of this lake is thus conjecturally, but in a natural and simple manner, accounted for by M. Rochet d'Hericourt. The depth of the innermost basin of the gulf of Tajura is not less than 600 feet, or 120 feet below the surface of the salt lake. He supposes the lake to have been anciently a part of the gulf, and to have been dyked off from it by volcanic action. Receiving no fresh water, except after rains, it has been gradually diminished by evaporation, and five hundred cubic feet of depth may be supposed to have been lost since the upheaving took place. According to this conjecture, the bed of the lake and of the adjacent sea are on the same level, but the surface of the lake has been reduced below that of the sea, in the lapse of years, by the evaporation of a torrid climate, acting without sufficient compensation. In striking contrast with the depression of these lakes, is the height of others in the following table, which exhibits remarkable variations. Killarney, Ireland Neagh, ditto Corrib, ditto Erne, ditto Derg, ditto Allen, ditto Skene, Scotland Wettur, Sweden Wcner, ditto Strand, Norway Miose Vand, ditto Oresund ditto Superior, North America Huron, ditto Erie, ditto Ontario, ditto Feet above the Level of the Sea. 50 48 16 140 98 16O . 1300 288 144 . 1137 • 1576 . 2400 . 623 591 565 234 Michigan, North America Nicaragua. Central America Titicaca, Peru Sir-i-Kol, Central Asia Geneva, Switzerland Neufchatel, ditto Lucerne, ditto Annecy, ditto Zurich, ditto Maggiore, Italy Como, ditto Iseo, ditto Garda, ditto Albano, ditto Nemi, ditto Van, Armenia Feet above the Level of the Sea. - 594 134 - 13,000 - 15,600 - 1152 - 1437 - 1320 - 1460 - 1279 64O - 650 - 630 - 256 - 919 - 1022 - 5467 4. The last class of lakes have both affluents and outlets. These are the most numerous. They are sometimes formed by a number of streams flowing into a central basin, from whence the superabundant waters escape by one principal outlet, or they occur in the channel of a great river, and are the receptacles of its waters, which re-issue 318 PHYSICAL GEOGRAPHY. at a point opposite to where they entered. Such are the principal lakes of Switzerland, and the Scandinavian peninsula, of Ladoga and Onega in Russia, and the Lake Baikal in Southern Siberia. The latter is the Holy Sea of the Russians, the largest body of fresh water on the eastern continent, and the largest of all mountain lakes. It lies embosomed in the ranges which form part of the northern rampart of the high central table-land of Asia, and is supposed to be not less than 1200 miles in circumference, occupying a space more than equal to the half of Scotland. Its principal tributary, among upwards of 160, is the Selinga, from the south, which has a course of 700 miles, and drains a country not inferior in extent to the whole of Great Britain ; and through a narrow and deep crevice in the mountains on the north-west it discharges its surplus waters by the Lower Angura, which joins the Yenesei, and is conducted to the Arctic Ocean. Naturalists have been unable to account for the existence of the salmon, the seal, and a kind of sponge, in the fresh water of the Baikal, otherwise than by supposing that in some remote age it was connected with the northern sea. To the same class the large inland seas of Canada belong, which form a chain of magnificent fresh-water expanses, upon the smallest of which frigates of the first magnitude have sailed, war been waged, and whose surface is tempest-tost like the ocean. The river St. Louis enters Lake Superior, the first of the chain in point of size, or reckoning from the west, besides an immense number of nameless streams from the surrounding country, where dense woods and long-continued frosts prevent evaporation from carrying off any large quantity of the superficial waters. The surplus tide of Lake Superior, which has a circumference of 1750 miles, passes by river channels into the Huron, Erie, and Ontario Lakes, which, together with Lake Michigan, form one of the most important inland water-communications of the globe. Scarcely inferior to these in size are the lakes to the north, which occupy the fur countries of America, and occur in chains. The communication is direct from 55° N. lat. in a north-westerly course, through Deer, Wollaston, and Athabasca Lakes, to the Great Slave and Bear Lakes, a distance of near 2000 miles, only interrupted by falls and rapids in the connecting rivers. From the eastern extremity of the Great Slave Lake another chain extends in a north easterly direction, which Captain Back traversed to the Polar Sea in his celebrated expedition in search of Captain Ross. Through great part of the year these lakes are ice-bound, adventurous travellers and the fur traders commonly passing over their frozen surface in dog-sledges. This is the case with the north European and Asiatic lakes, across. which an active commerce is carried on in the winter season. But some defy the rigour of the climate to bind up their waters, owing to their depth, or peculiar agitations to which they are subject. Loch Ness, in Scotland, never freezes ; and though ice is found in the bogs and morasses around Lake Baikal, even during the heat of summer, it does not cover up the lake itself before the middle or close of December. Passing from this arrangement of lakes into systems, we proceed to glance at a few of the more striking peculiarities which characterise them indifferently. Floating islands, in several instances of considerable size, are found in some of the lakes of Scotland, Ire land, Sweden, Germany, and Italy. We have an account of one in the latter country in the following letter addressed by Pliny to Gallus. It is only necessary to remark, that the lake Vadimon, the scene of the phenomenon, is now the Lago di Bassanello. " Those works of art or of nature, which are usually the motives of our travels, are often overlooked and neglected, if they happen to lie within our reach ; whether it be that we are naturally less inquisitive concerning those things which are near us, while our curiosity is excited by remote objects ; or because the easiness of gratifying a desire is always sure to damp it ; or, perhaps, that we defer, from time to time, viewing what we know we have an opportunity of seeing whenever we please. Be the reason what it LAKES. 319 may, it is certain there are several rarities in and near Rome, which we not only have never seen, but have never so much as heard of ; and yet, if they had been the produc tion of Greece, or Egypt, or Asia, or any other country which we admire as fruitful in wonders, they would, long since, have been the subjects both of our reading, conversa tion, and inspection. For myself, at least, I confess I have lately been entertained with a sight of one of these our indigenous singularities, to which I was an entire stranger before. My wife's grandfather desired I would look upon his estate near Ameria. As I was walking over his grounds, I was shown a lake that lies below them, called Vadimon, which I was informed had several very extraordinary qualities attending it. This raised my curiosity to take a nearer view. Its form is exactly circular ; there is not the least obliquity or winding ; but all is regular and even, as if it had been hollowed and cut out by the hand of art. The water is of a clear sky-blue, though with somewhat of a green ish cast ; it seems, by its taste and smell, impregnated with sulphur, and is deemed of great efficacy in all fractures of the limbs, which it is supposed to consolidate. Notwith standing it is but of a moderate extent, yet the winds have a great effect upon it, fre quently throwing it into violent commotions. No vessels are suffered to sail here, as its waters are held sacred, but several floating islands swim about in it, covered with reeds and rushes, together with other plants, which the neighbouring marsh and the borders of the lake produce. These islands differ in their size and shape ; but the edges of all of them are worn away by their frequent collision against the shore and each other. They have all of them the same height and motion, and their respective roots, which are formed like the keel of a boat, may be seen hanging down in the water, on whichever side you stand. Sometimes they move in a cluster, and seem to form one entire little continent ; sometimes they are dispersed into different quarters by the winds ; at other times, when it is calm, they float up and down separately. You may frequently see one of the larger islands sailing along with a lesser joined to it, like a ship with its long-boat ; or, perhaps, seeming to strive which shall out-swim the other : then again they all assemble in one station, and afterwards joining themselves to the shore, sometimes on one side and some times on the other, cause the lake to appear considerably less, till at last uniting in the centre, they restore it to its usual size. The sheep which graze upon the borders of this lake frequently go upon these islands to feed, without perceiving that they have left the shore, till they are alarmed by finding themselves surrounded with water ; and in the same manner, when the wind drives them back again, they return, without being sensible that they are landed. This lake empties itself into a river, which after running a little way sinks underground ; and if any thing is thrown in, brings it up again where the stream emerges. I have given you this account, because I imagined it would not be less new nor less agreeable to you than it was to me ; as I know you take the same pleasure as myself in contemplating the works of nature." There are various examples of these floating islands. Those of the lake Gerdau in Prussia are said to afford sufficient pasturage for a hundred head of cattle, which have actually been found grazing on them, and noble elms grow upon one in the lake Kolk, in Osnabriick. These islands have been formed by the gradual agglomeration of vegetable matter, reeds from the marshes and roots of trees, upon which the waters have deposited fine sand and gravel held in suspension, and have obviously required ages for their growth. The great raft near the mouth of the Mississippi is a production of an analo gous kind. This is composed of the wood annually drifted down that river and its tribu taries, consisting of the magnificent trees growing upon their banks, which fall into the waters, owing to the floods undermining their foundations and loosening their roots. Ar rested by some obstruction in the river, a mass of timber has thus accumulated, and become consolidated by the interlacing of weeds and the deposition of alluvium, so as to form what 320 PHYSICAL GEOGRAPHY. is called " the raft," the dimensions of which in 1816 amounted to a length of 10 miles, a width of 220 yards, and a depth of 8 feet. This is an island afloat in the bosom of the waters, having externally the appearance of solid land, for green bushes and a variety of beautiful ilowers bloom upon its surface. The age of the raft, at the time when the pre- cedin"1 dimensions were given, is supposed to have been not more than thirty-eight years, from which some idea may be formed of the immense quantity of drift-wood borne down by the waves of the Mississippi. The Swiss lakes exhibit some peculiar and interesting features. That of Zurich presents annually what is called the flowering of its waters. This is the appearance upon the surface of a very minute vegetation. But the lake of Geneva, or Lac Leman, furnishes the most remarkable phenomenon. This is generally considered the finest inland sheet of water in southern Europe. It fills a great cavity in the rocky strata of Switzerland, extending about forty-seven miles in its greatest length, and nine miles in its greatest breadth. High and rugged mountains form its boundary to the east, with more gentle slopes to the west, enriched with corn fields, villas, and vineyards. The turbid and discoloured waters of the Khone are filtered in it, and issue forth beautifully clear and pellucid. Owing to this deposition from the river, the lake has been largely contracted at the point where the stream enters, so that the Roman town, Portus Valesise, which was close to the water's edge, is now separated from it by a tract of land more than a mile and a half in breadth. Among the peculiarities of the lake of Geneva, is that called Seiches, by the people of the neighbourhood. It consists in a sudden rising of the water, in the form of a tidal wave, sometimes to the height of five or six feet in the course of a few hours. A few of the Italian lakes, and some others of the Swiss, are subject to the same great undulatory movement, the cause of which is by no means certain, but con ceived to lie in some local and transient variation of the pressure of the atmosphere. There is another phenomenon of which this lake is the scene, called the Vaudaise. This is the ebullition of its waters, arising perhaps from the escape of subaqueous currents of air or gases. The agitation produced is at times so violent as to render the navigation of the lake dangerous. The appearance of tumult upon the surface of lakes without any sensible cause for it, is far from being uncommon, however strange it must seem, to see their waters tossing to and fro, in the calmest weather, when not a twig is stirring in the woods upon their banks. On the 1st of November 1755, without the least apparent cause, agitation seized the before peaceful waters of Loch Lomond, and they suddenly rose against their shores to a perpendicular height of two feet, and then subsided below their ordinary level. This was soon afterwards explained by the coincident occurrence of the earthquake at Lisbon. But Loch Lomond, along with lake Wetter in Sweden, often exhibit great disturbance, the cause of which must lie in themselves, and is probably due to the escape of currents of air from below their bed, though obscurity rests upon the manner of the form ation of this subaqueous and subterranean prison-house of the winds, or upon the opening of its doors. In the winter season, a lake near Boleslaw in Bohemia, which has never been sounded, also exhibits upon its surface the effects of the action of some internal force ; large masses of ice being whirled from it into the air. But of all phenomena of this kind, those which mark the Baikal are the most singular and unaccountable. They give it somewhat of a prophetic character, and would justify incredulity were they not well attested. It is rarely the case that its waters are smooth and calm, but when they are so, vessels upon their surface are often so violently shaken as to make it difficult to stand in them. There is commonly an undulation, which the sailors call kolychen or zyb, which increases previous to a wind arising. This undulation proceeds from the quarter of the wind, and its increase precedes it by about an hour ; but while a moderate wind will be LAKES. 321 attended with great disturbance on the lake, a storm will produce much less effect. These circumstances have some connection with the physical condition of the district — a focus of earthquakes — but the links between the two are unknown to us; another evi dence, that, in the physics of the earth, there is much yet beyond the reach of our philo sophy. A small expanse of water near Beja in Portugal is said to announce a storm by its commotions ; but, in general, the movements of lakes are confined to those produced by their own river-currents, and the action of the external atmosphere. Winds produce an effect upon their surface, regulated by the extent exposed to their influence, and the character of the surrounding shores. The heavy autumnal gales that sweep over the ample volume of Lake Superior, rouse it into tempest, and raise its waters several feet upon the opposite beach ; and small mountain-lakes are often violently agitated by the winds, which rush with greater power through the openings in their boundary, from the interruption which its walls present to their course. Lake Saratoga. The smaller lakes of America, whose wild and solitary shores attract the tourist, of which the above view of Lake Saratoga affords a specimen, have some singular physical pecu liarities. One of the early explorers of its northern regions, Sir Alexander Mackenzie, was the first to notice the attractive power of the mud at the bottom, which is some times so great, that boats can with difficulty proceed along the surface. This extra ordinary fact is thus stated: — "At the portage or carrying place of Martres, on Kose Lake, the water is only three or four feet deep, and the bottom is muddy. I have often plunged into it a pole twelve feet long, with as much ease as if I merely plunged it into the wateV. Nevertheless, this mud has a sort of magical effect upon the boats, which is such that the paddles can with difficulty urge them on. This effect is not perceptible on the south side of the lake, where the water is deep, but is more and more sensible as you approach the opposite shore. I have been assured that loaded 322 PHYSICAL GEOGRAPHY. boats have often been in danger of sinking, and could only be extricated by being towed by lighter boats. As for myself, I have never been in danger of foundering, but I have several times had great difficulty in passing this spot with six stout rowers, whose utmost efforts could scarcely overcome the attraction of the mud. A similar phenomenon is observed on the Lake Saginaga, whose bottom attracts the boats with such force that it is only with the greatest difficulty that a loaded boat can be made to advance : fortunately the spot is only about four hundred yards over." This statement has received confirma tion from the experience of Captain Back, during the recent arctic land expeditions. A part of Lake Huron, likewise, in the same district, appears to be the centre of a remarkable electrical attraction. There is a bay in the lake, over which the atmosphere is constantly highly charged with electricity, and it has been affirmed that no person has ever traversed it without hearing peals of thunder. Lakes differ greatly in their colour, clearness, and depth. It is difficult to account in every case for the tints of water. They are referable to a variety of causes. The geological character of the beds of lakes, of the surrounding objects from which shadows are cast, and of the soil drained by them ; their depth, with the nature and quantity of the subaqueous vegetation, have influence in determining the colour of their waters. Those of the Great Bear Lake are a beautiful light blue, especially in the vicinity of the primitive mountains of M'Tavish Bay, where they are very transparent. A piece of white rag, when simk here, did not disappear till it had descended to the depth of ninety feet. This remarkable transparency belongs to the waters of Lake Superior, which are so pellucid that the fish and rocks are distinctly visible at most extraordinary depths. Those of Lake Huron also are brilliantly crystalline ; and to a voyager on some of the Scandinavian lakes, the density of the medium on which he is floating appears little greater than that of the atmosphere. So completely are the senses here sometimes deceived, that the stranger has recoiled in involuntary alarm from his situation, impressed with the idea of being about to be precipitated among the rocks and chasms disclosed below him. " Nothing," says Elliot, in his letters from the north of Europe, " appears more singular to a foreigner than the transparency of the waters of the Norwegian lakes. At the depth of 100 or 120 feet the surface of the ground beneath is perfectly visible ; sometimes it may be seen wholly covered with shells, sometimes only sprinkled with them ; now a submarine forest presents itself to view, and now a subaqueous mountain." A farthing has been seen at the depth of 120 feet in Lake Wetter in Sweden. The depth of lakes, of which a few examples are given below, is very various ; and all efforts to sound some have failed, owing to the line running out without reaching the bottom. Greatest Soundings. Feet. Lough Neagh - 102 Killarney - 252 Lomond, average depth 1 20 feet 720 Ness - 810 Constance - 2334 Geneva, medium depth 5GO - 900 Neuchatel Lucerne Zurich Maggiore Como Iseo - 426 GOO 600 2625 1698 984 Garda Nemi Wetter Wena, average depth 240 Mcela Caspian Sea - Superior Huron Erie - - Ontario Michigan - , Greatest Soundings. Feet. 951 2700 440 573 66 2800 1200 1000 270 300 900 Some lakes are periodical, their waters retiring into subterranean reservoirs through crevices in their beds, from whence they successively re-issue. This is the case with LAKES. J23 lake Cirknitz in Illyria, which displays frequent intermission, dependent, in the period of its occurrence, upon the season. It has been full for three or four years together, and dry twice or thrice in the year. We