ahr: 2 me Coe ae Srna ae a es one Sie ae ean Bacay Sg a8. ae SaaS Ba Rees, re wats See SOeraees = ms = i r - “ * = : | x . x . z ? ; 7 | . . i : = | , | | i | ® : 4 Set ies > MS ates nig 3 “ : ze d ‘ S = : } 3 - 2 2 SP SS zs . > =r om F 7 3 ) : | ne KI AA A : A i ae x pee Aah *, Ae y aoe ae Ne wei NAA’ ony Ny : hy, i x Some nt ee ne vrrph bis Ow ae sAacee nat” “9 i es oP eh THE DEPTHS OF THE SEA. + THE DEPTHS OF THE SEA. AN ACCOUNT OF THE GENERAL RESULTS OF THE DREDGING CRUISES OF H.MSS. ‘PORCUPINE’ AND ‘LIGHTNING DURING THE SUMMERS OF 1868, 1869, AND 1870, UNDER THE SCIENTIFIC DIRECTION OF Dh. CARPENTER, F.R.S., J. GWYN JEFFREYS, F.R.S., AND DR. WYVILLE THOMSON, F.R.S. C. WYVILLE THOMSON, LL.D., D.Sc., F.R.SS. L. &E., F.LS., F.G.S., Erc. Regius Professor of Natural History in the University of Edinburgh, And Director of the Civilian Scientific Staf of the ‘Challenger’ Exploring Expedition. WITH NUMEROUS ILLUSTRATIONS AND MAPS. SECOND EDITION. Tondo: MACMILLAN AND CO. 1874. [ The Right oF Translation and Reproduction is reserved. | =, , ae 6 we tr ~~ oO a _ ‘<< iP © Yi ——— Ww ier = —— i : ra Be: ¥ a ‘A @ ¥y die Pa . 7

: ey iO Ree “a -_ a)? ae a? eS x : he - sf ae ly | LONDON: R. CLAY, SONS, AND TAYLOR, PRINTERS, BREAD STREET HILL. e 4 7 : : : ; 7 a . fi TO MEAD A Mi niks tO 15> iN This Volume is dedieated, GRATEFUL REMEMBRANCE OF THE PLEASANT TIMES SPENT BY HIMSELF AND HIS COMRADES AT THE GOVERNOR’S HOUSE IN THORSHAVN, THE AUTHOR. PREFACE. Ar the close of the Deep-sea Dredging Expeditions which had been undertaken by the Admiralty at the instance of the Council of the Royal Society during the years 1868, 1869, and 1870, it was thought right that those who had been entrusted with their scien- tific direction should, in addition to their official reports, lay before the general public some account of their proceedings with the objects ;—first, of show- ing, if possible, that the value of the additions which had been made to human knowledge justified the liberality of Government in acceding to the request of the Council of the Royal Society, and placing means at their disposal to carry out the desired researches ; and, secondly, of giving such a popular outline of the remarkable results of our work as might stimulate general interest, and induce those who have the proclivities and the opportunity, to penetrate farther into the new and strange region on whose borders we have had the- good fortune to have been among the first to encroach. Sat PREFACE. It was originally intended that the general account should have been a joint production, each of us con- tributing his part. There were difficulties, however, in the way of this arrangement. We were all fully occupied with other matters, and the amount of communication and correspondence between us, re- quired to carry out the plan of joint authorship, seemed likely to prove a cumbrous complication. It was therefore decided that guoad the popular exposition I should take upon myself the office of ‘reporter,’ and thus it comes about that I am indi- vidually and solely responsible for the opinions and statements contained in this book, save where they are included within quotation marks, or their sources otherwise acknowledged. Since we began these deep-sea investigations, inquiries have come in from all quarters, both at home and abroad, as to the implements and methods which we employ. To supply the desired informa- tion, I have described, in detail, the processes both of sounding and dredging; and I hope that the special chapters, on these matters—the result of considerable experience—may be found useful to beginners. I pretend to no special knowledge of physics, and I should have greatly preferred confining myself to the domain of Biology, my own proper province ; but certain physical questions raised during our late explorations have so great importance in relation to PREFACE. 1X the distribution of living beings, and have of late been brought into so great prominence by Dr. Car- penter, that it has been impossible for me to avoid giving my earnest consideration to their eeneral bearings on Physical Geography, and forming decided opinions, which, I regret to say, do not altogether coincide with those of Dr. Carpenter. The chief points on which my friend and I ‘agree to differ’ are discussed in the chapter on the Gulf-stream. It was at first my intention that appendices should be added: to the different chapters, containing lists and scientific descriptions of the animal forms which were observed. This it was found impossible to ac- complish, chiefly on account of the large number of undescribed species which were placed in the hands of the experts who undertook the examination of the several groups. I am not sure that, even if it had been possible to furnish them in time, such lists would have been altogether an appropriate addition to what is intended merely as a popular preliminary sketch. The metrical system of measurement, and the centigrade thermometer scale, have been adopted throughout the volume. The metrical system is pro- bably familiar to most of my readers. In ease the centigrade notation, which comes in very frequently owing to the frequent discussion of questions of the distribution of temperature, should not be equally familiar, a comparative scale, embodying those of 45 KEE si Allman, FES., PREFACE. Fahrenheit, Celsius, and Réau- mur, is introduced for com- parison. My various sources of infor- mation, and the friendly as- sistance I have received on all hands during the progress of our work, are acknowledged, so far as possible, in the text. I need here only renew my to May and the officers of the thanks Staff-Commander ‘Lightning,’ and Captain Cal- ver and the officers of the ‘Porcupine,’ without whose hearty sympathy and co-ope- ration our task could never have been satisfactorily accom- plished; to my colleagues, Dr. Carpenter, FE.R.S., and Mr. Gwyn Jeffreys, E.R.S., have cordiaily assisted me in who every way in their power; and to the naturalists into whose hands the animals of various classes were placed for descrip- tion and study,—the Rev. A. Merle Norman, Professor Kol- liker, Dr. Carter, (F. Rist we Professor Martin Duncan, I.R.S., PREFACE. xi and Dy. M‘Intosh, for information courteously supplied. ve The whole of the illustrations in the book—with the exception of the vignettes of F&éroe scenery for which I am indebted to the accomplished pencil of Madame Holten—are by my friend Mr. J. J. Wild. I need scarcely thank him for the admirable way in which he has accomplished his task, for every figure was with him a labour of love, and I almost envy him the gratification he must feel in the result. To Mr. J. D. Cooper I owe my sincere thanks for the singularly faithful and artistic rendering of Mr. Wild’s beautiful drawings on the wood-blocks. On the return of the ‘ Porcupine’ from her last cruise, so much interest was felt in the bearings of the new discoveries upon important biological, geo- logical, and physical problems, that a representation was made to Government by the Council of the Royal Society, urging the despatch of an expedition to traverse the great ocean basins, and take an out- line survey of the vast new field of research—the bottom of the sea. Rear-Admiral Richards, C.B., F.R.S., the Hydro- grapher to the Navy, warmly supported the pro- posal, and while I am writing a noble ship is lying at Sheerness equipped for scientific research, under his wise and liberal directions, as no ship of any nation was ever equipped before. X1i PREFACE. The scientific staff of the ‘Challenger’ are well aware that for some time to come their réle is to work and not to talk; but now, on the eve of depar- ture, I think it is only right to take this opportunity of saying that nothing has been left undone by the Government to ensure the success of the undertaking, and that dire misfortune only ought to prevent our furnishing a valuable return. C. WYVILLE THOMSON. EpINBURGH, December 2nd, 1872. Iz Ly Skaapen ROr Hod = > BB ~ eee’ LIBRARYi= CONT Bans: CHAPTER I. INTRODUCTION. The Question of a Bathymetrical Limit to Life-—The general Laws which regulate the Geographical Distribution of Living Beings.—Professor Edward Forbes’ Investigations and Views.—Specific Centres.—Repre- sentative Species.—Zoological Provinces.—Bearings of a Doctrine of Evolution wpon the Idea of a ‘ Species, and of the Laws of Distribution. —The Circumstances most likely to affect Life at great Depths: Pres- sure, Temperature, and Absence of Light... . ... ... ... Page 1 CHAPTER II. THE CRUISE OF THE ‘ LIGHTNING.’ Proposal to investigate the Conditions of the Bottom of the Sea.—Sugges- tions and Anticipations —Correspondence between the Council of the Royal Society and the Admiralty.—Departure from Stornoway.—The Féroe Islands.—Singular Temperature Results in the Froe Channel.— Life abundant at all Depths.—Brisinga coronata.—Holtenia carpentert. —General Results of the Expedition ... ... ... -- ... Page 49 Apprenpix A.—Particulars of Depth, Temperature, and Position at the various Dredging Stations of H.M.S. ‘Lightning, in the Summer of 1868 ; the Temperatures corrected for Pressure... ... .... Page 81 CHAPTER III. THE CRUISES OF THE ‘ PORCUPINE.’ The Equipment of the Vessel.—The first Cruise, under the direction of Mr. Gwyn Jeffreys, off the West Coast of Ireland and in the Channel between Scotland and Rockall.—Dredging carried down to 1,470 fathoms. ASV? X1V CONTENTS. —Change of Arrangements.—Second Cruise ; to the Bay of Biscay.— Dredging successful at 2,435 fathoms.—Third Cruise ; in the Channel between Froe and Shetland.—The Fauna of the ‘Cold Area.’ Page 82 Appenpix A.—Official Documents and Official Accounts of preliminary Proceedings in connection with the Explorations in H.M. Surveying- vessel ‘ Porcupine,’ during the Summer of 1869 ves’ ane ROGGE res Aprrnpix B,—Particulars of Depth, Temperature, and Position at the various Dredging Stations of H.M.S. ‘ Porcupine, in the Summer of USGOS Mee at ee eal Gite! be. Mae aa Muh ees oe tees, Sone ae eae ma CHAPTER IV. . Z _ ‘ - ’ . THE CRUISES OF THE ‘PORCUPINE’ (continued). From Shetland to Stornoway.—Phosphorescence.—The Echinothuride,.— The-Fauna of the ‘Warm Area.’—End of the Cruise of 1869.—Arrange- ments for the Expedition of 1870.—From England to Gibraltar. Peculiar Conditions of the Mediterranean.—Return to Cowes. Page 145 Apprnpix A.—Extracts from the Minutes of Council of the Royal Society, and other official Documents referring to the Cruise of H.M.S. ‘ Porcu- pine,’ during the Summer of 1870... ... ... ... ... «. Page 197 ApprenpIx B.—Particulars of Depth, Temperature, and Position at the various Dredging Stations of H.M.S. ‘ Porcupine, in the Summer of STON she se Sots leah eee tak, Weeel maeel) cohen) (dno ® eee acer) eae CHAPTER Y. DEEP-SEA SOUNDING. The ordinary Sounding-iead for moderate Depths.—Liable to Error when employed in Deep Water.—Early Deep Soundings unreliable.—Inproved Methods of Sounding.—The Cup-lead.—Brooke’s Sounding Instrument.— The ‘ Bull-dog ;’ Fitzgerald’s ; the ‘ Hydra.’—Sounding from the ‘ Porcu- pine. —The Contour of the Bed of the North Atlantic ... Page 205 CHAPTER VI. DEEP-SEA DREDGING. The Naturalist’s Dredge.—O. F. Muller.—Ball’s Dredge.—Dredging at The Dredge-rope.-_ Dredging in Deep Water.—The ‘Hempen tangtes.—Dredging on board the ‘ Porcupine. — The Sieves.— moderate Depths. CONTENTS. XV The Dredger’s Note-book.—The Dredging Committee of the British ~ Association.— Dredging on the Coast of Britain.—Dredging abroad.— History of the Progress of Knowledge of the Abvssal Fauna. Page 236 = AppEnDIx A.—One of the Dredging Papers issued by the British Associa- tion Committee, filled up by Mr. MacAndrew.... ... .... Page 281 CHAPTER VII. DEEP-SEA TEMPERATURES. Ocean Currents and their general Effects on Climate.—Determination of Surface Temperatures.—Deep-sea Thermometers.—The ordinary Self- registering Thermometer on Six’s principle-—The Miller-Casella modifi- cation. —The Temperature Observations taken during the Three Cruises of H.M.S. ‘ Porcupine’ in the year 1869, ete. cee roca ers Ueege. 284 AppENDIx A.—Surface Temperatures observed on board H.M.S. ‘ Porcupine’ during the Summers of 1869 and 1870 ... ... ... ... ..- Page 329 AvpenDIx B,—Teimperature of the Sea at different Depths near the Eastern Margin of the North Atlantic Basin, as ascertained by Serial and by Bottom Soundings... ... : 22s as “ave « Ge sae Appenpix C.—Comparative Rates oF edncuion of Temperature w a Increase of Depth at Three Stations in different Latitudes, all of them on the Eastern Margin of the Atlantic Basm ... ... ... Page 353 AppENDIx D.—-Temperature of the Sea at different Depths in the Warm and Cold Areas lying between the North of Scotland, the Shetland Islands, and the Fieroe Islands ; as ascertained by Serial and by Bottom Sound- ings. Sid iszd,, Soe | evo e APPENDIX E. Bete mediate Bottom Menem cnr: show ing the Intermixture of Warm and Cold Currents on the Borders of the Warm and Cold PATCAS Tones cree. Gree. hcl ie en hee a ges OO CHAPTER VIII. THE GULF-STREAM. The Range of the ‘ Porcupine’ Temperature Observations.— Low Tempera- tures universal at great Depths.—The Difficulty of investigating Ocean Currents.—The Doctrine of a general Oceanic Circulation advocated by Captain Maury and by Dr, Carpenter.—Opinion expressed by Sir John Herschel.—The Origin and Extension of the Gulf-stream.—The Views of Captain Maury; of Professor Buff; of Dr. Carpenter.— The Gulf-stream off the Coast of North America.—Professor Bache’s ‘ Sections. —The Gulf-stream traced by the Surface Temperatures of the North Atlantic.— (Mr. Findlay’s Views.—Dr. Petermann’s Temperature Charts.—Sources of XV1 OONTENTS. the underlying Cold Water.—The Arctic Return Currents.— Antarctic Indraught.— Vertical Distribution of Temperature in the North Atlantic BASU 5! Se ace ks” GE Sh CR Gio Ser Oe oc » CHAPTER IX. THE DEEP-SEA FAUNA. The Protozoa of the Deep Sea.—Bathybius.—‘ Coccoliths, and ‘ Cocco- spheres. —The Foraminifera of the Warm and Cold Areas.—Deep-sea Sponges. —The Hexactinellidee. — Rossella. — Hyalonema. — Deep-sea Corals. —The Stalked Crinoids.— Pentacrinus.— Rhizocrinus.— Bathy- crinus.—The Star-fishes of the Deep Sea.—The general Distribution and Relations of Deep-sea Urchins.—The Crustacea, the Mollusca, and the Fishes of the ‘Porcupine’ Expeditions .. ... ... ... .... Page 407 CHAPTER X. THE CONTINUITY OF THE CHALK. Points of Resemblance between the Atlantic Ooze and the White Chatk.— Differences between them.—Composition of Chalk.—The Doctrine of the Continuity of the Chalk.—Objections.—Arguments in favour of the View from Physical Geology and Geography.—Former Distribution of Sea and Land. — Paleontological Evidence. — Chalk-flints. — Modern Sponges and Ventriculites—Corals.—Kchinoderms.—Mollusca.— Opinions of Professor Huxley and Mr. Prestwich.—The Composition of Sea-water. —Presence of Organic Matter.—Analysis of the contained Gases.—Differ- ences of Specific Gravity—Conclusion ...... ... ... ... Page 467 AppEenDIx A.—Summary of the Results of the Examination of Samples of Sea-water taken at the Surface and at various Depths. By William Lant Carpenter, B.A., B.Sc. Pet ies Mra! 7/1/27" 15 |0)2 APPENDIX B. Fels of the imeleces a Bight Samples of Sea-water collected during the Third Cruise of the ‘ Porcupine.’ By Dr. Frank- lands ERS. © Sac ns is noes ane genoa APPENDIX C.—Notes on Spccmene of te Bottom enlleoted during the First Cruise of the ‘ Porcupine’ in 1869. By David Forbes, F.R.S. Page 514 AppENnpDIx D.—Note on the Carbonic Acid contained in Sea-water. By John Young Buchanan, M.A., Chemist to the ‘ Challenger’ Expedition. Page 518 BINGE a ee TT TMOG es PD ae FIG, 18. iG} LIST OF ILLUSTRATIONS. WOODCUTS. ASTEROPHYTON LINCKII, Miiller and Troschel. A young speci- men slightly enlarged (No. 75) ... A, Grae eee GLOBIGERINA BULLOIDES, D’Orbigny. Highly magnified .. ORBULINA UNIVERSA, D’Orbigny. Highly magnified CARYOPHYLLIA BOREALIS, Sages Twice the natural size. (No. 45) Pgs eon sete pa BRISINGA CORONATA, G. 0. Sn ‘Wael size. (No. 7)... HOLTENIA CARPENTERI (sp.n.). Half the natural size. (No. 12) ’ TISIPHONIA AGARICIFORMIS (sp. n.). Natural size. (No. 12) ... GONOPLAX RHOMBOIDES, Fabricius. Young. Twice the natural size. (No. 3) ae aeelniane 3P5. gh VRE Ae: GERYON TRIDENS, pobes Young. Twice the natural size. (No. 7) Serato bar Sooo Ree Eee ORBITOLITES TENUISSIMUS, Gampenter ‘Mss. Magnified. (No. De ee mance. Oe Oey LR. 7 oe ee ee PoROCIDARIS PURPURATA (sp. n.). Natural size. (No. 47) PoOURTALESIA JEFFREYSI (sp. n.). Slightly enlarged. (No. 64) STYLOCORDYLA BOREALIS, Lovén (sp.). Natural size. (No. 64) SoLASTER FURCIFER, Von Duben and Koren. Natural size. (No. 55) Reg gee oat Cee ean as KOoRETHRASTER HISPIDUS WO fee pecs aspect. Twice the natural size. (No. 57) hig Priel Se tah eM ae HYMENASTER PELLUCIDUS *) Ventral aspect. Natural size. (No. 59) itt, ft are ie eran ARCHASTER BIFRONS (sp. ae Dotal aspect. Three-fourths of the natural size. (No. 57) Evsirvus cuspipatus, Kroyer. (No. 55) aie ; CAPRELLA SpPrINosissimA, Norman. Twice the Sr tineale size. (No;.59)) ZL. oe: XVI LIST OF ILLUSTRATIONS. Aiea wasuTa, Norman. Slightly enlarged. (No.55) ... -.- ARCTURUS BAFFINI, Sabine. About the natural size. (No. Nympnon apyssorum, Norman. Slightly enlarged. (No. 56) THECOPHORA SEMISUBERITES, Oscar Schmidt. ‘Twice the natural BIZGbemENOf (0) pleat © coe) Win. wee. ann nd aeecoe Aeon ease mmee THECOPHORA IBLA (sp. n.). Twice the natural size. (No. 76) ARCHASTER VEXILLIFER (sp. n.). One-third the natural size. (ING. 7G) G22 08-2 3d Disks © sochecke: Bn eee Mouoasren FULGENS os n.). One-third the natural size. (No. CALVERIA HYSTRIX (3 sp. n. oh Two-thirds the natural size. (No. 86) See out 4¢ : * : mod CALVERIA HYSTRIX Gn n. he Taner ganic of a Eten of the test showing the structure of the ambvlacral and interambu- lneral areas-..5 ..0 siaitiege RE CALVERIA FENESTRATA ee nO Gee of the Fe Wied pedi- cellarize sit sek) set, casee: ese LOPHOHELIA PROLIFERA, Pallas ( el Three-fourths the natural size. < CNO#26)" «as. Veh sane, eee foe ere os er ALLOPORA OCULINA, Bhrenber awh) wien cad ue A eO ee OPHIOMUSIUM LYMANI (sp. n.). Dorsal anes Natural size. (No. 45) OpuromusIUM LYMANI ae Bie Oral ones) Dorynenus tHomsonir, Norman. Once and a half tie neice size ; everywhere in deep water i gai Badin see AMATHIA CARPENTERI, Norman. Once and a half the natural size; (Nig CAi) ease gals jeses Wigs) Thue’) (cola CHRONDROCLADIA VIRGATA al n.). One-half the natural size. CNio:, 33;0P Ih. Vwi 2c Oe ee ee Pre" CuP-LWAD.” | cc * oct abe ete eee ek ee a Brooke’s Drer-SEA Sounpina APPARATUS ... ... ... Tue ‘ Buuu-Dog’ Sounpinc MAcHINE ee TR Eat. oss THE ‘FITZGERALD’ SOUNDING MACHINE. ... ... 1... «ss. cos SERRE byaD RAC S ONIDIENG: UA CELUI: ne enone a SONTAG Sti] Sans OUINID ING. IVIPACENTNIE) 7) eel enna me oT ae OTHO ces Muuurr’s Drepes. a.p. 1750 SB ATT Se DREDGE eee ae sie gna. SO kgaae nance ealet aree Tue SrerRN Derrick oF THE ‘PORCUPINE,’ SHOWING THE ‘ ACCUMULATOR, THE DREDGE, AND THE MODE OF STOWING MVEDE) TINROPE tote. cars. icc. se “uses go? sk ee Toe END oF THE Damnen. FRAME ere het occ PAGE 127 128 129 147 148 150 153 156 248 250 FIG. - 58. 59. 60. 61. 62. LIST OF ILLUSTRATIONS. 3 Foo aaa SHOWING THE Mopk or ATTACHMENT OF THE Bae BF SPAS ae Tor END OF THE Damone FRAME, SHOWING THE Mone OF ATTACHMENT OF THE BaG 5 : ee DIAGRAM OF THE RELATIVE POSITION OF THE WHE THE WEIGHTS, AND THE DREDGE, IN DREDGING IN Deep WATER DREDGE wiTH ‘HEMPEN TANGLES’ ... .. Set or Drepa@iIne SIEVES ... .. re 4 he ates Tur MILLER-CASELLA Monsreanpete OF © Se Ss ae REGISTER- ING THERMOMETER ... ..- aE ee ME TE Le et ee Copper CASE FOR PROTECTING THE MiLurr-CAsELLA THER- MOMETER SERIAL SouNDING, Station 64 SERIAL Souwonees Station 87 A st ae ; E CURVES CONSTRUCTED FROM SERIAL SGenineei IN THE a W: ARMW’- AND ‘ CoLp-AREAS’ IN THE CHANNEL BETWEEN SCOTLAND AND F ROE sae ee in RS CURVES CONSTRUCTED FROM SERIAL AND MEGaion Souwomas IN THE CHANNEL BETWEEN SCOTLAND AND ROCKALL DIAGRAM REPRESENTING THE RELATION BETWEEN DEPTH AND TEMPERATURE OFF RocKALL S33 a heen DIAGRAM REPRESENTING THE RELATION BETWEEN Depen AND TEMPERATURE IN THE ATLANTIC BASIN ... .... ... see CURVES CONSTRUCTED FROM SERIAL AND Bortom Mie amaatie SOUNDINGS IN THE ATLANTIC BASIN ... tee Eat DIAGRAM REPRESENTING THE RELATION BETWEEN Desi AND TEMPERATURE, FROM THE ‘l'EMPERATURE. OBSERVATiONS TAKEN BETWEEN CAPE FINISTERRE AND CaPE St. VINCENT, AueusT 1870 s.. oe SURE Et Ne ete enMeaccey tare “EINE GROSSERE CYTODE VON Baers MIT EINGEBETTETEN Cocconmrermny Ge 100) 4s. > ac Son Shah iad Fe tee ‘ CoccosPHERE’ (x. 1000) Se Eset aee RossELLA VELATA (sp. n.). Natural size. (No. 32, 1870) HYALONEMA LUSITANICUM, Barboza du Bocage. Half the natural sizes, NCNOS 90; 1869) 22) Sa ee . 5 ar - . ~ as - < + = . oh) Le = _ cad ca 4 7 : . | - ‘ Soy ‘ie - = 4 ‘ 4 . , s » i al + - ees a - vie * r » An “a . « i Pa Li _ a a ee! = i a Pa So =») ; ; aie =<. 7°: | s THE DEPTHS OF THE SEA. THE DEPTHS OF THE SEA. CalyAr Eisner: INTRODUCTION. The Question of a Bathymetrical Limit to Life.—The general Laws which regulate the Geographical Distribution of Living Beings.— Professor Edward Forbes’ Investigations and Views.—Specific Centres.—Representative Species.—Zoological Provinces.—Bear- ings of a Doctrine of Evolution upon the Idea of a ‘ Species,’ and of the Laws of Distribution.—The Circumstances most likely to affect Life at great Depths: Pressure, Temperature, and Absence of Light. THE sea covers nearly three-fourths of the surface of the earth, and, until within the last few years, very little was known with anything like certainty about its depths, whether in their physical or their biological relations. The popular notion was, that after arriving at a certain depth the conditions became so peculiar, so entirely different from those of any portion of the earth to which we have access, as to preclude any other idea than that of a waste of utter darkness, subjected to such stupendous pressure as to make life of any kind impossible, and to throw insuperable diffi- "aie 2 B 2 THE DEPTHS OF THE SEA. [cHar. 1. << culties in the way of any attempt at investigation. Even men of science seemed to share this idea, for they gave little heed to the apparently well-authenti- cated instances of animals, comparatively high in the scale of life, having been brought up on sounding lines from great depths, and welcomed any suggestion of the animals having got entangled when swimming on the surface, or of carelessness on the part of the observers. And this was strange, for every other question in Physical’ Geography had been investi- gated by scientific men with consummate patience and energy. Every gap in the noble little army of martyrs striving to extend the boundaries of know- ledge in the wilds of Australia, on the Zambesi, or towards the North or South Pole, was struggled for by earnest volunteers, and still the great ocean slumbering beneath the moon covered a region apparently as inaccessible to man as the ‘mare serenitatis.’ A few years ago the bottom of the sea was required for the purpose of telegraphic communication, and practical men mapped out the bed of the North Atlantic, and devised ingenious methods of ascertain- ing the nature of the material covering the bottom. They laid a telegraphic cable across it, and the cable got broken and they went back to the spot and fished up the end of it easily, from a depth of nearly two miles. It had long been a question with naturalists whether it might not be possible to dredge the bottom of the sea in the ordinary way, and to send down water- bottles and registering instruments to settle finally the question of a ‘zero of animal life,’ and to deter- cnar, 1] INTRODUCTION. 3 mine with precision the composition and temperature of sea-water at great depths. An investigation of this kind is beyond the ordinary limits of private enter- prise. It requires more power and sea skill than naturalists can usually command. When, however, in the year 1868, at the instance of my colleague Dr. Carpenter and myself, with the effective support of the present Hydrographer to the Navy, who is deeply interested in the scientific aspects of his profession, we had placed at our disposal by the Admiralty sufficient power and skill to make the experiment, we found that we could work, not with so much ease, but with as much certainty, at a depth of 600 fathoms as at 100; and in 1869 we carried the “operations down to 2,435 fathoms, 14,610 feet, nearly three statute miles, with perfect success. Dredging in such deep water was doubtless very trying. Each haul occupied seven or eight hours; and during the whole of that time it demanded and received the most anxious care on the part of our commander, who stood with his hand on the pulse of the accumulator, ready at any moment, by a turn of the paddles, to ease any undue strain. The men, stimulated and encouraged by the cordial interest taken by their officers in our operations, worked willingly and well; but the labour of taking upwards of three miles of rope coming up with a heavy strain, from the surging drum of the engine, was very severe. The rope itself, ‘hawser-laid,’ of the best Italian hemp, 24 inches in circumference, with a breaking strain of 24 tons, looked frayed out and worn, as if it could not have been trusted to stand this extraordinary ordeal much longer. 4 THE DEPTHS OF THE SEA. | CHAP. I. Still the thing is possible, and it must be done again and again, as the years pass on, by naturalists of all nations, working with improving machinery, and with ever-increasing knowledge. For the bed of the deep sea, the 140,000,000 of square miles which we have now added to the legitimate field of Natural History research, is not a barren waste. It is inhabited by a fauna more rich and varied on account of the enormous extent of the area, and with the organisms in many cases apparently even more elaborately and delicately formed, and more exquisitely beautiful in their soft shades of colouring and in the rainbow-tints of their wonderful phosphorescence, than the fauna of the well-known belt of shallow water teeming with innumerable invertebrate forms which fringes the land. And the forms of these hitherto unknown living beings, and their mode of life, and their rela- tions to other organisms whether living or extinct, and the phenomena and laws of their geographical distribution, must be worked out. The late Professor Edward Forbes appears to have been the first who undertook the systematic study of Marine Zoology with special reference to the distribu- tion.of marine animals in space and in time. After making himself well acquainted with the fauna of the British seas to the depth of about 200 fathoms by dredging, and by enlisting the active co-operation of his friends-—among whom we find MacAndrew, Barlee, Gwyn Jeffreys, William Thompson, Robert Ball, and many others, entering enthusiastically into the new field of Natural History inquiry—in the year 1841 Forbes joined Capt. Graves, who was at that time in command of the Mediterranean Survey, as naturalist. cUAP. I. ] INTRODUCTION. 5 During about eighteen months he studied with the utmost care the conditions of the Aegean and its dredging operations at depths varying from 1 to 1380 fathoms. In 18438 he communicated to the Cork meeting of the British Association an elaborate report on the Mollusca and Radiata of the digean Sea, and on their distribution considered as bearing on Geology.' Three years later, in 1846, he published in the first volume of the ‘ Memoirs of the Geological Survey of Great Britain,’ a most valuable memoir upon the Connection between the existing Fauna and Flora of the British Isles, and the geological Changes which have affected their Area, especially during the Epoch of the Northern Drift.’ In the year 1859 appeared the Natural History of the European Seas by the late Professor Edward Forbes, edited and continued by Robert Godwin Austen.’ In the first hundred pages of this little book, Forbes gives a general outline of some of the more important of his views with regard 1 Report on the Mollusca and Radiata of the Avgean Sea, and on their Distribution, considered as bearing on Geology. By Edward Forbes, F.L.S., M.W.S., Professor of Botany in King’s College, London. (Report of the Thirteenth Meeting of the British Association for the Ad- vancement of Science ; held at Cork in August 1843. London, 1844.) 2 On the Connection between the Distribution of the existing Fauna and Flora of the British Isles and the geological Changes which have affected their Area, especially during the Epoch of the Northern Drift. By Edward Forbes, F.R.S., L.8., G.S., Professor of Botany at King’s College, London ; Palontologist to the Geological Survey of the United Kingdom. (Memoirs of the Geological Survey of Great Britain, vol. i. London, 1846.) 3 The Natural History of the European Seas, by the late Professor Edward Forbes, F.R.S., &c. Edited and continued by Robert Godwin Austen, F.RS8. London, 1859. 6 THE DEPTHS OF THE SEA. [CHAP. I. to the distribution of marine forms. ‘The remainder of the book is a continuation by his friend Mr. Godwin Austen, for before it was finished an early death had eut short the career of the most accomplished and original naturalist of his time. I will give a brief sketch of the general results to which Forbes was led by his labours, and I shall have to point out hereafter, that although we are now inclined to look somewhat differently on certain very fundamental points, and although recent inves- tigations with better appliances and more extended experience have invalidated many of his conclusions, to Forbes is due the credit of having been the first to treat these questions in a broad philosophical sense, and to point out that the only means of acquiring a true knowledge of the rationale of the distribution of our present fauna, is to make ourselves acquainted with its history, to connect the present with the past. This is the direction which must be taken by future inquiry. Forbes, as a pioneer in this line of research, was scarcely in a position to appreciate the full value of his work. Every, year adds enormously to our stock of data, and every new fact indicates more clearly the brilliant results which are to be obtained by following his methods, and by emulating his enthusiasm and his indefatigable industry. | Forbes believed implicitly, along with nearly all the leading naturalists of his time, in the immutability of species. He says (Natural History of the British Seas, p. 8), ‘‘ Every true species presents in its indi- viduals, certain features, specific characters, which distinguish it from every other species; as if the Creator had set an exclusive mark or seal on each CHAP. I.| INTRODUCTION. 7 ’ type.” He likewise believed in specific centres of distribution. He held that all the individuals com- posing a species had descended from a single pro- genitor, or from two, according as the sexes might be united or distinct, and that consequently the idea of a species involved the idea of the relationship in all the individuals of common descent ; and the converse, that there could by no possibility be community of descent except in living beings which possessed the same specific characters. He supposed that the original individual or pair was created at a particular spot where the conditions were suitable for its existence and propagation, and that the species extended and migrated from that spot on all sides over an area of greater or less extent, until it met with some natural barrier in the shape of unsuitable conditions. No specific form could have more than a single centre of distribution. If its area appeared to be broken up, a patch not in connection with the original centre of distribution occurring in some distant locality, it was accounted for by the formation, through some geolo- gical change after the first spread of the species, of a barrier which cut off a part of its area; or to some accidental transport to a place where the conditions were sufficiently similar to those of its natural original habitat to enable it to become naturalized. No species once exterminated was ever recreated, so that in those few cases in which we find a species abundant at one period over an area, absent over the same area for a time, and recurring at a later period, it must be ac- counted for by a change in the conditions of the area which forced the emigration of the species, and a sub- sequent further change which permitted its return. 5 THE DEPTHS OF THE SEA. [CHAP. I. Forbes defined and advocated what he called the law of representation. He found that in all parts of the world, however far removed, and however completely separated by natural barriers, where the conditions of life are similar, species and groups of species. occur which, although not identical, resemble one another very closely; and he found that this similarity existed likewise between groups of fossil remains, and between groups of fossils and groups of recent forms. Admitting the con- stancy of specific characters, these resemblances could not be accounted for by community of de- scent, and he thus arrived at the generalization, that in localities placed under similar circumstances, similar though specifically distinct specific forms were created. These he regarded as mutually repre- sentative species. Our acceptance of the doctrines of specific centres and of representation, or, at all events, the form in which we may be inclined to accept these, depends greatly upon the acceptance or rejection of the funda- mental dogma of the immutability of species; and on this point there has been a very great change of opinion within the last ten or twelve years, a change certainly due to the remarkable ability and candour with which the question has been discussed by Mr. Darwin’ and Myr. Wallace,’ and to the genius of Pro- 1 The Origin of Species by means of Natural Selection ; or, the Preservation of Favoured Races in the Struggle for Life. By Charles Darwin, M.A, F.R.S., L.S., G.S., &. &e. London, 1859, and subse- quent editions. 2 Contributions to the Theory of Natural Selection. A Series of Essays by Alfred Russel Wallace. London, 1870. CHAP. 1. | INTRODUCTION. 9 fessor Ernst Haeckel, Dr. Fritz Miiller,’ and others of their enthusiastic disciples and commentators. I do not think that I am speaking too strongly when I say that there is now scarcely a single competent general naturalist who is not prepared to accept some form of the doctrine of evolution. There is, no doubt, very great difficulty in the minds of many of us in conceiving that, commencing from the simplest living being, the present state of things in the organic world has been produced solely by the combined action of ‘atavism,’ the ten- dency of offspring to resemble their parents closely ; and ‘variation,’ the tendency of offspring to differ individually from their parents within very narrow limits: and many are inclined to believe that some other law than the ‘survival of the fittest’ must regulate the existing marvellous system of extreme and yet harmonious modification. Still it must be admitted that variation is a vera causa, capable, within a limited period, under favourable circum- stances, of converting one species into what, accord- ing to our present ideas, we should be forced -to recognize as a different species. And such being the _ case, it is, perhaps, conceivable that during the lapse of a period of time—stiil infinitely shorter than eternity—variation may have produced the entire result. 1 Generelle Morphologie der Organismen. Allgemeine Grundziige der organischen Formen-Wissenschaft mechanisch begriindet durch die von Charles Darwin reformirte Descendenz-Theorie. Von Ernst Haeckel. Berlin, 1866.—Natiirliche Schépfungsgeschichte. Von Dr. Ernst Haeckel, Professor an der Universitit Jena. Berlin, 1870. 2 Fir Darwin. Von Dr. Fritz Miiller. Leipzig, 1864. Translated from the German by W. S. Dallas, F.L.S. London, 1869. 10 THE DEPTHS OF THE SEA. (CHAP. 1. The individuals comprising a species have a definite range of variation strictly limited by the circum- stances under which the group of individuals is placed. Except in man, and in domesticated animals in which it is artificially increased, this individual variation is usually so slight as to be unappreciable except to a practised eye; but any extreme variation which passes the natural limit in any direction clashes in some way with surrounding circumstances, and is dangerous to the life of the individual. The normal or graphic line, or ‘line of safety,’ of the species, lies midway between the extremes of variation. If at any period in the history of a species the conditions of life of a group of individuals of the species be gradually altered, with the gradual change of circumstances the limit of variation is contracted in one direction and relaxed in another; it becomes more dangerous to diverge towards one side and more desirable to diverge towards the other, and the position of the lines limiting variation is altered. The normal line, the line along which the specific characters are most strongly marked, is consequently slightly deflected, some characters being more strongly expressed at the expense of others. ‘This deflection, carried on for ages in the same direction, must even- tually carry the divergence of the varying race far beyond any limit within which we are in the habit of admitting identity of species. But the process must be infinitely slow. It is difficult to form any idea of ten, fifty, or a hundred millions of years; or of the relation which such periods bear to changes taking place in the organic world. CHAP. 1.] INTRODUCTION. Teal We must remember, however, that the.rocks of the Silurian system, overlaid by ten miles’ thickness of sediment é¢ntombing a hundred successive faune, each as rich and varied as the fauna of the present day, themselves teem with fossils fully representing all the existing classes of animals, except perhaps the highest. If it be possible to imagine that this marvellous manifestation of Eternal Power and Wisdom involved in living nature can have been worked out through the law of ‘descent with modification’ alone, we shall certainly require from the Physicists the longest row of cyphers which they can afford. Now, although the admission of a doctrine of evolu- tion must affect greatly our conception of the origin and rationale of so-called specific centres, it does not practically affect the question of their existence, or of the laws regulating the distribution of species from their centres by migration, by transport, by ocean currents, by elevations or depressions of the land, or by any other causes at work under existing circum- stances. So far as practical naturalists are con- cerned, species are permanent within their narrow limits of variation, and it would introduce an element of infinite confusion and error if we were to regard them in any other light. The origin of species by descent with modification is as yet only a hypothesis. During the whole period of recorded human observa- tion not one single instance of the change of one species into another has been detected; and, singular to say, in successive geological formations, although new species are constantly appearing and there is abundant evidence of progressive change, no single case 12 THE DEPTHS OF THE SEA. [CHAP. I. has‘yet been observed of one species passing through a series of inappreciable modifications into another. Every species appears to have an area of maximum development, and this has been called the metropolis of the species; and practically we must employ the same methods in investigating the laws of its distri- bution as if we still regarded it as having been specially created in its metropolis. It is the same in dealing with the law of represen- tation. Accepting an evolution doctrine, we should certainly regard closely allied or ‘representative’ species as having descended comparatively recently from a common ancestry, and as having diverged from one another under somewhat different conditions of life. It is possible that as our knowledge increases we may be able to trace the pedigree of our modern species, and some attempts have already been made to sketch out the main branches of the universal genealogical tree ;* but practically we must continue to accord a specific rank to forms which exhibit characters to which we have been in the habit of assigning specific value. «Every species has three maxima of develop- ment,—in depth, in geographic space, in time. I» depth, we find a species at first represented by few individuals, which become more and more numerous until they reach a certain point, after which they again gradually diminish, and at length altogether disappear. So also in the geographic and geologic distribution of animals. Sometimes the genus to which the species belongs ceases with its disappear- ance, but not unfrequently a succession of similar 1 Ernst Haeckel, op. cit. CIEAP. 1.] INTRODUCTION. 13 e species are kept up, representative as it were of each other. When there is such a representation, the minimum of one species usually commences before that of which it is representative has attained its correspondent minimum. Forms of representative species are similar, often only to be distinguished by critical examination.””’ As an illustration of what is meant by the law of ‘representation,’ I may cite a very curious case men- tioned by Mr. Verril and Mr. Alexander Agassiz. On either side of the Isthmus of Panama the Echinoderm order Hehinidea, the sea-urchins, are abundant; but the species found on the two sides of the Isthmus are distinct, although they belong almost universally to the same genera, and in most cases each genus is represented by species on each side which resemble one another so closely in habit and appearance as to be at first sight hardly distinguishable. I arrange a few of the most marked of these from the Carib- bean and Panamic sides of the Isthmus in parallel columns. Hastern Fauna. WESTERN Fauna. Cidaris annulata, GRay. Cidaris thouarsii, Vat. Diadema antillarum, Put. Diadema mexicanum, A, Ac. Echinocidaris punctulata, Desmu. LE chinocidaris stellata, Ac. Echinometra michelini, Des. Echinometra van brunti, A. AG. o viridis, A, AG. rupicola, A. Aa. Lytechinus variegatus, A. AG. Lytechinus semituberculatus, A. Ag. Tripneustes ventricosus, AG. Tripneustes depressus, A. AG. Stolonoclypus ravenellii, A. AG. Stolonoclypus rotundus, A. Ac. Mellita testudinata, Ku. Mellita longifissa, Micn. * Edward Forbes, Report on Aigean Invertebrata, op. cit. p. 173. 14 THE DEPTHS OF THE SEA. [CHAP. I. Eastern Fauna. WESTERN Fauna. Mellita hecapora, A. AG. Mellita pacifica, Vmr. Encope michelini, AG. Encope grandis, Ac. - emarginata, AG. » micropora, AG. Rhyncholampas caribbearum, Rhynchclampas pacificus, A. Aa. A, Aa. Brissus columbaris, Aa. Brissus obesus, VER. Meoma ventricosa, LUTK. Meoma grandis, GRAY. Plagionotus pectoralis, Ac. Plagionotus nobilis, A. Ac. Agassizia excentrica, A. AG. Agassizia scrobiculata, V Au. Mera atropos, Micu. Mera clotho, Micu. Supposing species to be constant, this singular chain of resemblances would indicate simply the special creation on the two sides of the Isthmus of two groups of species closely resembling one another, because the circumstances under which they were placed were so very similar; but admitting ‘ descent with modification,’ while gladly availing ourselves of the convenient term ‘ representation,’ we at once come to the conclusion that these nearly allied ‘ re- presentative species’ must have descended from a com- mon stock, and we look for the cause of their diver- gence. Now on examining the Isthmus of Panama we find that a portion of it consists of cretaceous beds containing fossils undistinguishable from fossils from the cretaceous beds of Europe; the Isthmus must therefore have been raised into dry land in tertiary or post-tertiary times. It is’ difficult to doubt that the rising of this natural barrier isolated two portions of a shallow-water fauna which have since slightly diverged under slightly different conditions. I quote Alexander Agassiz :—‘‘ The question naturally arises, have we not in the different Fauneze on both sides of the Isthmus a standard by which to measure the CHAP. 1. ] INTRODUCTION. 15) changes which these species have undergone since the raising of the Isthmus of Panama and the isolation of the two Faune ?’’? Edward Forbes distinguished round all seaboards four very marked zones of depth, each characterised by a distinct group of organisms. ‘The first of these is the littoral zone, the space between tide-marks, distinguished by the abundance of sea-weeds, on the European shores of the genera Lichina, Fucus, Enteromorpha, Polysiphona, and Laurencia, which severally predominate at different heights in the zone, and subdivide it into subordinate belts like a softly-coloured riband border. This band is under very special circumstances, for its inhabitants are periodically exposed to the air, to the direct rays of the sun, and to all the extremes of the climate of the land. Animal species are not very numerous in the littoral zone, but individuals are abundant. The distribution of many of the littoral species is very wide, and some of them are nearly cosmopolitan. Many are vegetable feeders. Some characteristic genera on the coast of Europe are Gammarus, Talitrus, and Balanus among Crustacea, and Lit- torina, Patella, Purpura, and Mytilus among Mol- lusea, with, under stones and in rock-pools, many stragglers from the next zone. The Laminarian zone extends from low-water mark to a depth of about fifteen fathoms. This is specially * Preliminary Report on the Echini and Starfishes dredged in Deep Water between Cuba and the Florida Reef, by L. F. de Pourtales, Assistant U.S. Coast Survey; prepared by Alexander Agassiz. Communicated by Professor B. Peirce, Superintendent U.S. Coast Survey, to the Bulletin of the Museum of Comparative Zoology, Cambridge, Mass., 1869. 16 THE DEPTHS OF THE SEA. [CHAP. 1. the zone of ‘tangles’ for the first few fathoms, and in deeper water of the beautiful scarlet sea-weeds (floridee). It is always under water except at the very lowest ebb of spring tides, when we get a glimpse of its upper border. The laminarian zone produces abundance of vegetable food, and, like the littoral zone, may be divided into subordinate bands distinguished by differently tinted alge. Animals swarm in this zone, both as to species and indi- viduals, and are usually remarkable for the bright- ness of their colouring. The molluscan genera Trochus, Lacuna, and Lottia are characteristic of this belt in the British seas. The Laminarian zone is succeeded by the Coralline zone, which extends to a depth of about fifty fathoms. In this belt vegetation is chiefly represented by coral- like millipores, and plant-like hydroid zoophytes and bryozoa abound. All of the higher orders of marine invertebrates are fully represented, principally by animal feeders. The larger crustaceans and echino- derms are abundant; and the great fishing-banks frequented by the cod, haddock, halibut, turbot, and sole, belong properly to this zone, although they sometimes extend into water more than fifty fathoms deep. Characteristic molluscan genera are Buccinum, . Fusus, Ostrea, and Pecten ; and among echinoderms in the European seas we find Antedon sarsi and celticus, Asteracanthion glaciale and rubens, Ophio- thrix fragilis, and on sand, Ophioglypha lacertosa and albida. The last belt defined by Forbes as extending from about fifty fathoms to an unknown lower limit is the zone of deep-sea corals. ‘In its depths the number CHAP. 1.] INTRODUCTION. 177 of peculiar creatures are few, yet sufficient to give a marked character to it, whilst the other portions of its population are derived from the higher zones, and must be regarded as colonists. As we descend deeper and deeper in this region, its inhabitants become more and more modified, and fewer and fewer, indicating our approach towards an abyss where life is either extinguished, or exhibits but a few sparks to mark its lingering presence.”’ ? Forbes pointed out that the groups of animals having their maximum development in these several zones are thoroughly characteristic, and that groups of representative forms occupy the same zones all over the world, so that on examining an assemblage of marine animals from any locality, it is easy to tell from what zone of depth they have been procured. At all periods of the earth’s history, there has been the same clear definition of zones of depth, and fossil animals from any particular zone are in some sense representative of the fauna of the corresponding zone at_the present day. We can, therefore, usually tell with tolerable certainty to which zone of depth a particular assemblage of fossils is to be referred. Although we must now greatly modify our views with regard to the extent and fauna of the zone of deep-sea corals, and give up all idea of a zero of animal life, still we must regard Forbes’ investiga- tion into the bathymetrical distribution of animals as marking a great advance on previous knowledge. His experience was much wider than that of any other naturalist of his time; the practical difficulties in the way of testing his conclusions were great, and * Edward Forbes, Natural History of the European Seas, p. 26. C 18 THE DEPTHS OF THE SEA. [CHAP. I. they were accepted by naturalists generally without question. The history of discovery bearing upon the extent and distribution of the deep-sea fauna will be dis- cussed in a future chapter. It will suffice at present to mention in order the few data which gradually pre- pared the minds of naturalists to distrust the hypo- thesis of a zero of animal life at a limited depth, and led to the recent special investigations. In the year 1819 Sir John Ross published the official account of his voyage of discovery during the year 1818 in Baffin’s Bay.' At page 178 he says, “ In the meantime I was employed on board in sounding and in trying the current, and the temperature of the water. It being perfectly calm and smooth, I had an excellent opportunity of detecting these important objects. Soundings were obtained correctly in 1,000 fathoms, consisting of soft mud, in which there were worms, and, entangled on the sounding-line, at the depth of 800 fathoms, was found a beautiful Caput Meduse (Fig. 1). These were carefully preserved, and will be found described in the appendix.” This was in lat. 73 37 N., long. 77° 25’ W., on the lst-of Sept: aor: and it is, so far as I am aware, the first recorded instance of living animals having been brought up from any depth approaching 1,000 fathoms. General Sir Edward Sabine, who was a member of Sir John Ross’s expedition, has kindly furnished Dr. 1 A Voyage of Discovery made under the Orders of the Admiralty in His Majesty’s ships ‘ Isabella’ and ‘ Alexander,’ for the purpose of exploring Baffin’s Bay, and inquiring into the Possibility of a North-west Passage. By John Ross, K.G., Captain Royal Navy. London, 1819. CHAP. T. | INTRODUCTION. L9 Carpenter with some more ample particulars of this Fic. 1.—Asterophyton linckii, MULLER and TRoscHEL. A young specimen slightly enlarged. No. 75, occurrence : '—‘‘ ‘The ship sounded in 1,000 fathoms, mud, between one and two miles off shore (lat. 1 Preliminary Report, by Dr. William B. Carpenter, V.P.R.S., of Dredging Operations in the Seas to the North of the British Islands, carried on in Her Majesty’s steam-vessel ‘Lightning,’ by Dr. Carpenter and Dr. Wyville Thomson. (Proceedings of the Royal Society, 1868, p. 177.) © ~~ 20 THE DEPTHS OF THE SEA. [CHAP. I. 73° 37’ N., long. 77° 25’ W.); a magnificent Asterias (Caput Meduse) was entangled by the line, and brought up with very little damage. The mud was soft and greenish, and .contained specimens of Lam- bricus tubicola.’ So far my written journal; but I ean add, from a very distinct recollection, that the heavy deep-sea weight had sunk, drawing the line with it, several feet into the soft greenish mud, which still adhered to the line when brought to the surface of the water. The star-fish had been entangled in the line so litile above the mud that fragments of its arms, which had been broken off in the ascent of the line, were picked up from amongst the mud.” Sir James Clark Ross, R.N., dredging in 270 fathoms, lat. 73° 3’ S., long. 176° 6 #., reports “ OCorallines, Flustre, and a variety of invertebrate animals, came up in the net, showing an abundance and great variety of animal life. Amongst these I detected two species of Pycnogonum; Idotea bafjini, hitherto considered peculiar to the Arctic seas; a Chiton, seven or eight bivalves and univalves, an un- known species of Gammarus, and two kinds of Serpula adhering to the pebbles and shells . . . It was interest- ing amongst these creatures to recognize several that I had been in the habit of taking in equally high northern latitudes; and although, contrary to the general belief of naturalists, I have no doubt that from however great _a depth we may be enabled to - bring up the mud and stones of the bed of the ocean, 1 A Voyage of Discovery and Research in the Southern and Antarctic Regions during the Years 1839-43. By Captain Sir James Clark Ross, R.N. London, 1847. CHAP. I. | INTRODUCTION. it we shall find them teeming with animal life; the extreme pressure at the greatest depth does not appear to affect these creatures; hitherto we have not been able to determine this point beyond a thousand fathoms, but from that depth several shell- fish have been brought up with the mud.” On the 28th of June, 1845, Mr. Henry Goodsir, who was a member of Sir John Franklin’s ill-fated expedition, obtained in Davis’ Strait from a depth of 300 fathoms, ‘‘a capital haul,—mollusca, crustacea, asterida, spatangi, corallines, &c.”’* The bottom was composed of fine green mud like that mentioned by Sir Edward Sabine. About the year 1854 Passed-midshipman Brooke, U.S.N., invented his ingenious sounding instrument for bringing up samples from the bottom. It only brought up a small quantity in a quill. These trophies from any depth over 1,000 fathoms were eagerly sought for by naturalists and submitted to a searching micro- ‘scopic examination; and the result was very surpris- ing. All over the Atlantic basin the sediment brought up was nearly uniform in character, and consisted almost entirely of the calcareous shells, whole or in fragments, of one species of foraminifer, Globigerina bulloides (Fig. 2). Mixed with these were the shells of some other foraminifera, and particularly a little perforated sphere, Orbulina universa (Fig. 3), which in some localities entirely replaces Globigerina ; with a few shields of diatoms, and spines and trellised skeletons of Radiolaria. Some soundings from the Pacific were of the same character, so 1 Natural History of the British Seas. By Professor Edward Forbes and kK. Godwin-Austen. P. 51. a2 THE DEPTHS OF THE SEA. (CHAP. I. that it seemed probable that this gradual deposition of a fine uniform organic sediment was’ almost universal. ~ Then the question arose whether the animals which secreted these shells lived at the bottom, or whether they floated in myriads on the surface and in the upper zones of the sea, their empty shells falling after death through the water in an incessant shower. Specimens of the soundings were sent to the eminent Fic. 2.—Globigerina bulloides, DOrpIGNy. Highly magnified. microscopists Professor Ehrenberg of Berlin and the late Professor Baily of West Point. On the moot question these two naturalists gave opposite opinions. Ehrenberg contended that the weight of evidence was in favour of their having lived at the bottom, while Baily thought it was not probable that the animals live at the depths where the shells are found, but that they inhabit the water near the CHAP. I. ] INTRODUCTION. Dey surface, and when they die their shells settle to the bottom.’ The next high authority who expressed an opinion was Professor Huxley, and he was very guarded. ‘The samples procured by Capt. Dayman in the ‘ Cyclops,’ Fic. 3.—Orbulina universa, D’ORBIGNY. Highly magnified. in 1857, were submitted to him for examination, and in his report to the Admiralty’ in 1858 he says :— 1 Explanations and Sailing Directions to accompany the Wind and Currents Charts. By M. F. Maury, LL.D., Lieut. U.S.N., Super intendent of the National Observatory. 6th Edition. Philadelphia, 1864. P. 299. 2 Appendix A to Deep Sea Soundings in the North Atlantic Ocean between Ireland and Newfoundland, made in H.M.S. ‘ Cyclops,’ Lieut.-Commander Joseph Dayman, in June and July 1857. Pub- lished by order of the Lords Commissioners of the Admiralty. London, 1858. Dek THE DEPTHS OF THE SEA. (CHAP: ies ‘‘ How can animal life be conceived to exist under such conditions of light, temperature, pressure, and aération as must obtain at these vast depths? To this one can only reply that we know for a certainty that even very highly-organized animals do contrive to live at a depth of 300 or 400 fathoms, inasmuch as they have been brought up thence, and that the difference in the amount of light and heat at 400 and at 2,000 fathoms is probably, so to speak, very far less than the difference in complexity of organization between these animals and the humble Protozoa and Proto- phyta of the deep-sea soundings. I confess, though, as yet, far from regarding it proved that the Glo- bigerine live at these depths, the balance of proba- bilities seems to me to incline in that direction.” In 1860 Dr. Wallich accompanied Captain Sir Leopold McChntock in H.M.S. ‘Bulldog’ on her sounding expedition to Iceland, Greenland, and New- foundland, as naturalist. During the cruise soundings were taken, and specimens of the bottom were brought up from depths from 600 to 2,000 fathoms; many of these were the now well-known erey ‘Globigerina ooze, while others were volcanic detritus from Iceland, and clay and gravel the product of the disintegration of the metamorphic rocks of Greenland and Labrador. On the return voyage, about midway between Cape Fare- well and Rockall, thirteen star-fishes came up from a sounding of 1,260 fathoms, “ convulsively embracing a portion of the sounding-line which had been payed out in excess of the already ascertained depth, and rested for a sufficient period at the bottom to permit of their attaching themselves to it.”” On his return Dr. Wallich published, in 1862, an extremely valuable CHAP. I.] INTRODUCTION. 95 work, which will be frequently referred to hereafter, upon ‘The Atlantic Sea-bed.’' He warmly advocated the view that the conditions of the bottom of the sea were not such as to preclude the possibility of the existence of even the higher forms of animal life, and discussed fully and with great ability the arguments which had been advanced on the other side. The first part only of Dr. Wallich’s book appeared, in a some- what costly and cumbrous form, and it scarcely came into the hands of working naturalists, or received the attention which it deserved. At the time, however, it was merely an expression of individual opinion, for no new facts had been elicited. Star-fishes had come up on several previous occasions adhering to sounding- lines, but the absolute proof was still wanting that they had lived upon the ground at the depth of the sounding. Dr. Wallich referred the star-fishes procured -to awell-known littoral species, and complicated their history somewhat irrelevantly with the disappearance of the ‘Land of Buss.’ Fortunately the artistic if not very satisfactory figure which he gives of a star- fish clinging to the line does not bear out his deter- mination either in appearance or attitude, but suggests one or other of two species which we now know to be excessively abundant in deep water in the North Atlantic, Ophiopholis aculeata, O. F. MiuiEer, or Ophiacantha spinulosa; Mittier and 'TROSCHEL. 1 The North Atlantic Sea-bed: comprising a Diary of the Voyage on board H.M.S. ‘Bulldog,’ in 1860; and Observations on the presence of Animal Life, and the Formation and Nature of Organic Deposits at great Depths in the Ocean. By G. C. Wallich, M.D., E.LS., F.G.8S., &. Published with the sanction of the Lords Com- missioners of the Admiralty. London, 1862. 26 a0 THE DEPTHS OF THE SEA. [CHAP. I. Dr. Wallich’s is the only book which discusses fully and systematically the various questions bearing upon the biological relations of the sea-bed, and his conclusions are in the main correct. In the autumn of the year 1860 Mr. Fleeming Jenkin, C.E., now Professor of Engineering in the University of Edinburgh, was employed by the Mediterranean Telegraph Company to repair their cable between Sardinia and Bona on the coast of Africa, and on January 15, 1861, he gave an interest- ing account of his proceedings at a meeting of the Institution of Civil Engineers.’ This cable was laid in the. year 1857. In 1858 it became necessary to repair it, and a length of about 30 miles was picked up and successfully replaced. In the summer of 1860 the cable completely failed. On taking it up in comparatively shallow water on the African shore, the cable was found covered with marine animals, greatly corroded, and injured appa- rently by the trawling operations in an extensive coral fishery through which it unfortunately passed. It was broken through in 70 fathoms water a few - miles from Bona. The sea-end was however recovered, and it was found that the cable which thence traversed a wide valley nearly 2,000 fathoms in maximum depth, was perfect to within about 40 miles of Sar- dinia. It was then picked up from the Sardinian end, and the first 39 miles were as sound as when it was first laid down. At this distance from the shore there was a change in the nature of the bottom, evidenced by the different colour of the mud, and the wires were 1 Minutes of Proceedings of the Institution of Civil Engineers, with Abstracts of the Discussions. Vol. xx. p. 81. London, 1861. CHAP. I. ] INTRODUCTION. Oi much corroded. Shortly afterwards the cable gave way in a depth of 1,200 fathoms, at a distance of one mile from the spot where the electrical tests showed that the cable had been previously broken. With these 40 miles of cable much coral and many marine animals were brought up, but it did not appear that their presence had injured the cable, for they were attached to the sound as well as to the corroded portions. On his return, Mr. Fleeming Jenkin sent specimens of the animals which he had himself taken from the cable, noting the respective depths, to Pro- fessor Allman, F.R.S., for determination. Dr. Allman gives a list of fifteen animal forms, including the ova of a cephalopod, found at depths of from 70 to 1,200 Fic. 4.—Caryophyllia borealis, FLeminc. Twice the natural size. No. 45 fathoms. On other portions of the cable species of Grantia, Plumularia, Gorgonia, Caryophyllia, Alcy- onium, Cellepora, Retepora, Eschara, Salicornaria, Ascidia, Lima, and Serpula. Y observe from Professor 28 THE DEPTHS OF THE SEA. [CHAP. I. Fleeming Jenkin’s private journal, which he has kindly placed in my hands for reference, that an example of Caryophyllia, a true coral (Fig. 4), was found naturally attached to the cable at the point where it gave way; that is to say, at the bottom in 1,200 fathoms water. Some portions of this cable subsequently came into the custody of M. Mangon, Professor at the Ecole des Ponts et Chaussées in Paris, and were examined by M. Alphonse Milne-Edwards, who read a paper upon the organisms attached to them, at the Academy of Sciences, on the 15th of July, 1861.1! After some introductory remarks which show that he is thoroughly aware of the value of this observation as a final solution of the vexed question of the existence of animal life at depths in the sea greatly beyond the supposed ‘ zero’ of Edward Forbes, M. Milne- the cable from the depth of 1,100 fathoms. The list includes Murex lamellosus, CRISTOFORI and JAN, and Craspedotus limbatus, PHILipp1, two univalve shells alhed to the whelk; Ostrea cochlear, Pout, a small oyster common below 40 fathoms throughout the Mediterranean ; Pecten teste, Bivona, a rare little clam; Caryophyllia borealis, FLEMING, or a nearly allied species, one of the true corals; and an unde- scribed coral referred to a new genus and species under the name of Thalassiotrochus telegraphieus, A. Mitne-Epwarbs. ! Observations sur l’Existence de divers Mollusques et Zoophytes a de trés grandes profondeurs dans la Mer Méditerranée: Annales des Sciences Naturelles ; quatrieme série—Zoologie, Tome xv. p. 149. Paris, 1861. CHAP. I. ] INTRODUCTION. 29 It is right, however, to state that Prof. Fleeming Jenkin’s notes refer to only one or two species, and especially to Caryophyllia borealis, as attached to the cable at a depth of upwards of 1,000 fathoms. From this depth he took examples of Caryophyllia with his own hands, but he suspects that specimens from the shallower water may have got mixed with those from the deeper in the series in the possession of M. Mangon, and that therefore M. Milne-Edwards’ list is not entirely trustworthy. Up to this time all observations with reference to the existence of living animals at extreme depths had been liable to error, or at all events to doubt, from two sources. ‘The appliances and methods of deep- sea sounding were imperfect, and there was always a possibility,from the action of deep currents upon the sounding-line or from other causes, of a greater depth being indicated than really existed; and again, although there was a strong probability, there was no absolute certainty that the animals adhering to the line or entangled on the sounding instrument had actually come up from the bottom. They might have been caught on the way. Before laying a submarine telegraphic cable its course is carefully surveyed, and no margin of doubt is left as to the real depth. Fishing the cable up isa delicate and difficult operation, and during its progress the depth is checked again and again. The cable lies on the ground throughout its whole length. The animal forms upon which our conclusions are based are not sticking loosely to the cable, under circum- stances which might be accounted for by their having been entangled upon it during its passage through the 30 THE DEPTHS OF THE SEA. [CHAP. I. water, but they are moulded upon its outer surface or cemented to it by calcareous or horny excretions, and some of them, such as the corals and bryozoa, from what we know of their history and mode of life, must have become attached to it as minute germs, and have grown to maturity in the position in which they were found. I must therefore regard this observation of Mr. Fleeming Jenkin as having afforded the_first absolute proof of the existence of highly-organized animals living at depths of upwards of 1,000 fathoms. During the several cruises of H.M. ships ‘ Light- ning’ and ‘ Porcupine’ in the years 1868, 1869, and 1870,' fifty-seven hauls of the dredge were taken in the Atlantic at depths beyond 500 fathoms, and six- teen at depths beyond 1,000 fathoms, and in all cases life was abundant. In 1869 we took two casts in depths greater than 2,000 fathoms. In both of these life was abundant: and with the deepest cast, 2,435 fathoms, off the mouth of the Bay of Biscay, we took living, well-marked, and characteristic examples_of all of the five invertebrate sub-kingdoms. And thus 1 Preliminary Report, by Dr. William Carpenter, V.P.R.S., of Dredging Operations in the Seas to the North of the British Islands, carried on in Her Majesty’s steam-vessel ‘ Lightning’ by Dr. Carpenter and Dr. Wyville Thomson, Professor of Natural History in Queen’s College, Belfast. (Proceedings of the Royal Society of London, 1868.) Preliminary Report of the Scientific Exploration of the Deep Sea in H.M. surveying-vessel ‘ Porcupine,’ during the Summer of 1869. Conducted by Dr. Carpenter, V.P.R.S., J. Gwyn Jeffreys, F.R.S., and Professor Wyville Thomson, LL.D., F.R.S. (Proceedings of the Royal Society of London, 1870.) Report of Deep Sea Researches carried on during the months of July, August, and September 1870, in H.M. surveying-ship ‘ Porcu- pine,’ by W. B. Carpenter, M.D., F.R.S., and J. Gwyn Jeffreys, F.R.S. (Proceedings of the Royal Society of London, 1870.) CHAP. I.] INTRODUCTION. 31 the question of the existence of abundant animal life at the bottom of the sea has been finally settled and for all depths, for there is no reason to suppose that the depth anywhere exceeds between three and four thousand fathoms; and if there be nothing in the conditions of a depth of 2,500 fathoms to prevent the full development of a varied fauna, it is impossible to suppose that even an additional thousand fathoms would make any great difference. The conditions which might be expected principally to affect animal life at great depths of the sea are pressure, temperature, and the absence of ight which apparently involves the absence of vegetable food. After passing a zone surrounding the land, which is everywhere narrow compared with the extent of the ocean, through which the bottom more or less abruptly shelves downwards and the water deepens ; speaking very generally, the average depth of the sea is 2,000 fathoms, or about two miles; as far below the surface as the average height of the Swiss Alps. In some places the depth seems to be considerably greater, possibly here and there nearly double that amount; but these abysses are certainly very local, and their existence is even uncertain, anda vast portion of the area does not reach a depth of 1,500 ‘fathoms. The enormous pressure at these great depths seemed at first sight alone sufficient to put any idea of life out of the question. There was a curious popular notion, in which I well remember sharing when a boy, that, in going down, the sea-water became gradually under the pressure heavier and heavier, and that all the loose things in the sea floated at different levels, 32 THE DEPTHS OF THE SEA. [CHAP, I. according to their specific weight: skeletons of men, anchors and shot and cannon, and last of all the broad gold pieces wrecked in the loss of many a galleon on the Spanish Main; the whole forming a kind of ‘ false bottom’ to the ocean, beneath which there lay all the depth of clear still water, which was heavier than molten gold. The conditions of pressure are certainly very extra- ordinary. At 2,000 fathoms a man would bear upon his body a weight equal to twenty locomotive engines, each with a long goods train loaded with pig iron. We are apt to forget, however, that water is almost incom- pressible, and that therefore the density of sea-water at a depth of 2,000 fathoms is scarcely appreciably increased. At the depth of a mile, under a pressure of about 159 atmospheres, sea-water, according to the formula given by Jamin, is compressed by the 34; of its volume; and at twenty miles, supposing the law of the compressibility to continue the same, by only + of its volume—that is to say, the volume at that depth vould be £ of the volume of the same weight of water at the surface. Any free air suspended in the water, or contained in any compressible tissue of an animal at 2,000 fathoms, would be reduced to a mere fraction of its bulk, but an organism supported through all its tissues on all sides, within and without, by incom- pressible fluids at the same pressure, would not necessarily be incommoded by it. We sometimes find when we get up in the morning, by arise of an inch in the barometer, that nearly half a ton has been quietly piled upon us during the night, but we expe- rience no inconvenience, rather a feeling of exhilara- tion and buoyancy, since it requires a little less exer- CHAP. I. | INTRODUCTION. 33- tion to move our bodies in the denser medium. We are already familiar, chiefly through the researches of the late Professor Sars, with a long list of animals of all the invertebrate groups living at a depth of 300 to 400 fathoms, and consequently subject to a pressure of 1,120 lbs. on the square inch; and off the coast of Portugal there is a great fishery of sharks (Centros- cymnus c@lolepis, Boc. and Cap.), carried on beyond that depth. If an animal so high in the scale of organization as a shark can bear without inconvenience the pressure of half a ton on the square inch, it is a sufficient proof that the pressure is applied under circumstances which prevent its affecting it to its prejudice, and there seems to be no reason why it should not tolerate equally well a pressure of one or two tons. At all events it is a fact that the animals of all the invertebrate classes which abound at a depth of 2,000 fathoms do bear that extreme pressure, and that they do not seem to be affected by it in any way. We dredged at 2,485 fathoms Scrobicularia nitida, MULLER, a_ species which is abundant in six fathoms and at all inter- mediate depths, and at 2,090 fathoms a large Fusus, with species of many genera which are familiar at moderate depths. Although highly organized animals may live when permanently subjected to these high pressures, it is by no means certain that they could survive the change of condition involved in the pres- sure being suddenly removed. Most of the mollusca and annelids brought up in the dredge from beyond 1,000 fathoms were either dead or in a very sluggish state. Some of the star-fishes moved for some time D 34 THE DEPTHS OF THE SEA. (CHAP. T. feebly, and the spines and pedicellariz: moved on the shells of the urchins, but all the animals had evi- dently received from some cause their death-shock. Dr. Perceval Wright mentions’ that all the sharks brought up by the long lines from 500 fathoms in Setubal Bay are dead when they reach the surface. Various methods have been proposed to test the actual pressure at great depths, but as all the elements: in the calculation are well known, it is easier to work out the question in the study than in the field. A neat instrument was constructed for the American Coast Survey. A brass piston or plunger was fitted accurately into a cylindrical hole in the wall of a brass water-tight chamber. The chamber was completely filled with water, and a clasping index on the plunger marked to what extent the plunger had been driven into the water contained in the chamber by the extreme pressure. The required indication is no doubt given, but such an instrument is at the same time an extremely delicate thermoscope, and until lately there has been no perfect means of correcting for temperature. A more important application of the pressure-gauge is to check the accuracy of deep soundings. Probably the best arrangement which has been proposed for the purpose is a long capil- lary glass tube, calibrated and graduated to milli- metres, open at one end, and provided with a moveable index to show to what amount the air contained in the tube has been compressed by the entrance of the water. The principal objection to this device is the 1 Notes on Deep Sea Dredging, by Edward Perceval Wright, M.D., F.L.S., Professor of Zoology, Trinity College, Dublin. (Annals and Magazine of Natural History, December 1868.) CHAP. I.] INTRODUCTION. Bi) great difficulty in arranging an index which will measure with accuracy the extremely small space into which even a long column of air is compressed when the pressure becomes very great. It can scarcely be made available beyond 1,000 fathoms (200 atmo- spheres). We have in Sir John Herschel’s ‘ Physical Geo- graphy,’ and in Dr. Wallich’s ‘ Atlantic Sea-bed,’’ where it is given in the fullest detail, the doctrine of the distribution of deep-sea temperature as it seems to have been almost universally adopted up to the time of the cruise of the ‘Lightning.’ It was gene- rally understood that while the surface temperature, which depended upon direct solar radiation, the direction of currents, the temperature of winds, and other temporary causes, might vary to any amount ; at a certain depth the temperature was permanent at 4° C., the temperature of the greatest density of fresh water. It is singular that this belief should have met with so general acceptance, for so early as the year 1833 M. Depretz*® determined that the temperature of the maximum density of sea-water, which contracts steadily till just above its freezing-point, is — 3°67 C. ; and even before that time observations of sea-tem- peratures at great depths, which were certainly trust- worthy within a few degrees, had indicated several degrees below the freezing-point of fresh water. The question of the distribution of heat in the sea, ' Physical Geography ; from the “ Encyclopedia Britannica.” By Sir John F. W. Herschel, Bart. K.H. &. &¢., p.45. Edinburgh, 1861. * Atlantic Sea-bed, p. 98. 3 Recherches sur le Maximum de Densité des Dissolutions aqueuses. (Annales de Chimie, tome Ixx. 1833, p. 54.) D 2 36 THE DEPTHS OF THE SEA. [crAP. 1. which is one of the greatest interest in connection with the distribution of marine animals, will be fully discussed in a future chapter. The broad conclusions to which we have been led by late investigations are, that instead of there being a permanent deep layer of water at 4° C. the average temperature of the bottom of the deep sea in temperate and tropical regions is about 0° C., the freezing-point of fresh water; and that there is a general surface movement of warm water, produced probably by a combination of various causes, from the equatorial regions towards the poles, and a slow under-current, or rather indraught, of cold water from the poles towards the equator. From cases which are recorded, chiefly by the early American sounding expeditions, of the sounding-line having been run out into long loops in soundings where, from the nature of the sea-bed, the bottom water appeared to be still, it would seem that there are also in some places intermediate currents; but with reference to their limits and distribution we have as yet no data. That a cold flow from the polar seas passes over the bottom seems to be proved by the fact that in all parts of the world wherever deep temperature sound- ings have been taken, from the arctic circle to the equator, the temperature sinks with increasing depth, and is lower at the bottom than the normal tempera- ture of the crust of the earth; an evidence that a constantly renewed supply of cold water is cooling down the surface of the crust, which, being a bad con- ductor, does not transmit heat with sufficient rapidity to affect perceptibly the temperature of the cold in- draught. It is probable that in winter, in those parts of the arctic sea which are not directly influenced by CHAP. 1. ] INTRODUCTION. SH the northern extension of the gulf stream, the whole column of water from the surface to the bottom is reduced to the lowest temperature which it will bear without freezing, and is thus an ample source of the coldest water of the highest specific gravity. The proof that the flow of the cold indraught is almost secular in its slowness, is that over a large portion of the ocean where the low bottom tempera- ture is known to prevail, the sea-bed is covered with a light fleecy deposit of microscopic organisms of great delicacy, into which the sounding-lead has in some instances sunk several feet, and which must inevitably be drifted away by a current of appreciable velocity. In all places where any perceptible current exists, the bottom consists of sand or mud or gravel and rolled pebbles. In some cases also, sounding in the deep water of the mid-Atlantic, the line, after running out greatly in excess of the depth, has been found to have coiled itself in a tangled mass right over the lead—a proof of almost absolute stillness. In some places, owing to the conformation of the neighbouring land or of the sea-bottom, warm and cold currents are circumscribed and localized, and this sometimes gives us the singular phenomenon of a patch or stripe of warm and a patch of cold sea meet- ing in an invisible but very definite line. There is a curious instance of this in the ‘cold wall’ which defines the western border of the gulf stream along the coast of Massachusetts, and another scarcely less marked which we discovered during the trial cruise of the ‘ Lightning’ has been fully described by Dr. Carpenter in his report of that cruise, and will be referred to hereafter. 38 THE DEPTHS OF THE SEA. [CHAP. I. In moderate depths sometimes the whole mass of water from the surface to the bottom is abnormally warm, owing to the movement in a certain direction of a great body of warm water, as in the ‘ warm area’ to the north-west of the Hebrides; and sometimes the whole body of water is abnormally cold, as in the ‘cold area’ between Scotland and Froe, and in the northern part of the German Ocean. In deep water, however, after the first few hundred fathoms, the thermometer usually sinks gradually and very slowly till it reaches its minimum at the bottom, a little above or below the zero of the centigrade scale. The temperature of the sea apparently never sinks at any depth below —3°'5 C., a degree of cold which, singularly enough, is not inconsistent with abundant and vigorous animal life, so that in the ocean, except perhaps within the eternal ice-barrier of the antarctic pole, life seems nowhere to be limited by cold. But although certain sea-animals—many of them, such as the siphonophora, the salpze, and the ctenophorous medusee, of the most delicate and complicated organiza- tion—are tolerant of such severe cold, it would appear to be temperature almost entirely which regulates the distribution of species. The nature of the ground can have little to say to it, for on every line of coast of any extent almost every condition and every kind of sediment is usually represented. From their inha- biting a medium which differs but little in weight from the substance of their bodies, and from the great majority of them producing free-moving larvee or fry in vast numbers which are floated along from place to place by currents, marine animals would seem to have every possible chance of extending their area, CHAP. T. | INTRODUCTION. 39 and yet the geographical distribution of most of the shallow-water species is well defined, and frequently somewhat restricted. Unfortunately we know as yet very little about the general distribution of marine animals. Except along the coasts of Britain and Scandinavia, a part of the North American coast, and a part of the Mediterranean, we know absolutely nothing beyond the shore zone, or at all events beyond 10 or 15 fathoms. What little we do know is con- fined almost entirely to the mollusca, and is due, not so much to scientific research as to the commercial value which the acquisitive zeal of conchologists has placed upon rare shells. It may be supposed, how- ever, that the same laws which regulate the distri- bution of littoral and sub-littoral mollusca, affect in hke manner that of shallow-water annulosa, echino- derms, and coelenterates ; indeed, from the scattered cbservations which have been made on the distribu- tion of these latter groups, it seems certain that such is the case. Woodward' regarded the marine mollusca as oceupy- ing eighteen well-defined ‘provinces,’ fulfilling more or less completely the condition of having at least one- half of the species peculiar to the province. Edward Forbes defined twenty-five such ‘regions ;’ but it must be remembered that in both cases at least three-fourths of the number of areas defined were based upon the most imperfect knowledge of the larger and more con- spicuous shore shells only. It has been constantly observed in the few cases confined entirely to the shores of the North Atlantic and the Mediterranean, 1 A Manual of the Mollusca. By S. P. Woodward. London, 1851. P, 354, 40 THE DEPTHS OF THE SEA. [CHAP. I. in which dredging has been attempted at any consider- able depth, say 30 or 40 fathoms, that the number of species common to the province dredged and to the province to the north of it, is greatly increased by the investigation being carried into a deeper zone.’ Thus in the lusitanian province Mr. McAndrew dredged off the coast of Galicia and Asturias, 212 species, 50 per cent. of which were common to the coast of Norway; and off the south of Spain 335 species were obtained, of which 28 per cent. were common to Norway (boreal province), and 51 per cent. to Britain (chiefly celtic province). The shells common to the two or three provinces were chiefly those dredged from considerable depths. The littoral forms had amuch more distinct aspect. The mollusca of the ‘Porcupine’ expedition have not yet been thoroughly worked out. ‘They are in the hands of Mr. Gwyn Jeffreys, and his preliminary reports give a most interesting forecast of what we may expect when his labour is completed. He announces something like 250 new species. Some of the more interesting of these, and the general phenomena of their distri- bution, will be referred to in a future chapter. The echinoderms of the expedition are more limited in number, and have already been examined by the writer with some care. The general distribution of the Echinodermata is not so well known as that of the Mollusca. There are many littoral and sub-littoral species. Many of these are local, but many have a wide geographical distribution, usually along what Edward Forbes calls a ‘homoiozoic belt,’ a belt of nearly similar circumstances of climate extending ' Woodward, loc. cit. p, 362. CHAP. 1.] INTRODUCTION. 4] through many degrees of longitude. but few of latitude. Asaclass, however, they prefer a depth rather beyond 20 fathoms,’ beyond the reach of very violent climatic vicissitudes. They are conspicuous things, showing usually sufficiently bold specific characters, and thus they are less liable to confusion than most other groups. They involve in their history and economy several of the principal questions discussed in this volume ; while giving, therefore, such a brief sketch as the space at my disposal and the amount of my present informa- tion may permit, of the additions which have been made during our dredging cruises to the knowledge of the other invertebrate classes, I will use the echi- noderms and the protozoa principally for the purpose of general illustration. Littoral and shallow-water species of animals must be much more liable to have their migrations inter- rupted by ‘natural barriers,’ such as deep water through which they cannot pass, or currents of warmer or of colder water; they must likewise be much more affected by local circumstances, such as extreme differences between summer and winter tem- perature ; so that they might be expected to be more circumscribed and local in their distribution than the denizens of greater depths—and they certainly are so. The conditions of the bottom in the zone from 20 to 50 fathoms are much more equable than near the surface. Direct solar radiation in temperate regions affects this zone very slightly, so that it probably 1 Distribution of Marine Life. By Professor Edward Forbes, F.R.S., President of the Geological Society. (From the Physical Atlas of Natural Phenomena, by Alexander Keith Johnston, F.R.G.S., &c. (Edinburgh, 1854.) 42, THE DEPTHS OF THE SEA. [cHAP. I. maintains nearly the same conditions of temperature through many degrees of latitude; and when as it passes southwards it does become gradually affected by increasing warmth, it may be supposed merely to sink a few fathoms deeper, carrying its conditions and its fauna along with it. For example, animal forms which abound in the celtic province at 25 fathoms with a mean temperature of 10° C. may be expected in greatest number in perhaps 40 or 50 fathoms, with the same temperature, in the lusitanian province. Such a zone may thus be continuous for a great dis- tance, while the surface climate has been altering greatly, and the migrations of littoral forms have been again and again interrupted. But the deeper zone also sometimes meets with a ‘ natural barrier,’ as at the line of junction between the warm and cold areas already mentioned; which causes a curious sifting out of those species which are intolerant of a change of temperature. ‘hus the fauna of the tem- perate northward flow of water off the west coast of Scotland is materially different from that of the cold indraught along the east coast. If there be this overlapping bétween the lusitanian and celtic provinces, the same relation may be antici- pated between our own and the boreal province; and it is well known that this is the case, for the great majority of the mollusca which have been dredged by McAndrew, Barlee, and especially by Gwyn Jeffreys, from depths below 50 fathoms, are identical with those found in shallower water on the Scandinavian coast. Our recent work, while it has brought out more fully the overlapping, has gone much farther towards the indication of a general law. CHAP. I.] INTRODUCTION. 43 It seems probable that the distribution of marine animals is determined by the extremes of temperature rather than by the means. The mean winter tempera- ture of the surface and of moderate depths off the north coast of Norway is about 2° C., and the extreme about 0° C.; and on the coast of Greenland the mean sinks to—1°C., and the extreme to —3° C. The temperature of the trough between Scotland and Feroe at the depth of 500 fathoms is from 0° to —1°C., and we find in that trough, along with many undescribed forms which are special to very deep water, every one of the echinoderms hitherto found on the coast of Scandinavia and Greenland, with the single exception, I believe, of Ophioglypha stiwitzii, a shallow-water Greenland form among the ophiurids, and of one or two holothurids which have as yet evaded us. The temperature of the telegraphic plateau at 1,000 to 2,000 fathoms is apparently usually from 3° to 2°C., and at 2,500 fathoms in the Bay of Biscay it is 2° C. From 800 to 2,000 fathoms all along the west coasts of Scotland, Ireland, and France, we have dredged Scandinavian echinoderms in abundance, and from the deep water as far south as the coast of Portugal I have received examples of some of the best marked northern forms, such as Hehinus elegans, D. and K. ; Toxopneustes drobachiensis, O. F. MULLER; Brissopsis lyrifera, ForBES; Tripylus fragilis, D. and K.; the magnificent Brisinga coronata, G. O. Sars (Fig. 7), and B. endecacnemos, ABSJORNSEN ; Pteraster mili- taris, M. and T.; Ophiacantha spinulosa, M. and 7. ; Ophiocten sericewn, Forses ; Ophioglypha sarsii, LirK.; } 51 38 12 50 + 251 Bl 7 Fe Lae A) 51 56 13 39 5 364 BS) 12°2 52 4 12 52 6 90 IM O)E (8) ee 52 25 11 40 c 159 HNO) 2: fis 52 14 11 48 8 106 10m, 12°3 53 15 it ot 9 165 9-8 1270 53 16 12 42 10 85 Gar i 12°5 53 23 13 29 11 1630 ~- — 53 24 15 24 12 670 5D ti 22 53 41 14 17 13 208 i) es 1, 53 42 13 55 14 173 O98 11-8 53. 49 13 15 1d 422 8 oO LG ge 54 5 12.17 16 816 4°2 see 54 19 11. 50 ee e230 3° 2 fies 54 28 11 44 18 185 Be tts 54 15 EU Eee) 19) 5/1360 3°0 1256 54 53 10 56 20 | 1443 pa 8) 13-0 pp 11. 113i 21 1476 Diath 13° 4 55 40 12 46 22 | 1263 7 8) 1338 56 8 13. 34 23 630 6° 4 14° 0 56. if 14 19 23a | 420 8-0 LOS i 56 13 14 18 24 109 ry 0) 14°3 56 26 14 28 29 F644 FB vi 56 41 13 39 cHaP.i.] THE CRUISES OF THE ‘PORCUPINE,’ 143 loftation. Tatuois eee reer. PULSE 26 345 Saaz C; 142 EC: 56° 58 N. Seal 2 NV ; Rockall Rockall =i oe Jo ae 4 Bank. ° 4 Bank. 28 1215 228 14-2 56 44 125 D2 29 1264 2% 1325 56 34 12 22 30 13580 DARTS Uae) 56 24 11 49 on 1360 DO 13°28 Donals 1b e25 32 1320 30 igor) 56 5 10 23 39 74 O28 18-4 50 38 S) aT 34 75 9-8 13-9 49" bil 10 12 35 96 Oz 17-4 49 7 LOror 36 125 Gert 1 Gai 48 50 ig O7 2435 2°5 iene) AT 38 128 38 2090 2°4 SOON) 47 39 di S35 ah) 557 8-3 ye 49 J] 11 56 40 pilleyi Saad ti 4 49 1 Ip 1) 41 584 San 17°4 49 4 12a 1 A9 862 4°3 Li 0 49 12 P22 a5 2, 45 1207 oD 125) 50) vl 12 26 44 865 Aali G52 50 20 11 34 45 458 Sig 15°9 wall bie 46 374 eh loll 59 23 7 4 47 542 6°5 12°2 59 34 (als) 48 540 — — 59) 32 Gag 49 A475 oA 12-0 59 43 7 40 | 50 355 ho) 11°4 59 54 ft o2 nag 440 Daree LOSS 60 6 8 14 eZ 384 | —0°8 1 Ee, 60 25 8 10 08 490 | —1°1 11°2 60 25 7 26 L 54 363 | —0°3 1f 4 59 56 6 27 9) 605 | —1°-2 5 let 60 4 og 56 480 | —0°7 11°4 60 2 (sya! 57 632),|.— 0-8 Ves gga 60 14 Opn 58 540 | —0°6 LOe6 60 21 6 bon 59 580 | —1°3 TES 60 21 5 Al 60 167 6-9 Sa ol 3 5 5S 61 114 ee 10-2 62 1 ls) 62 125 (Geax) 9-8 61 59 4 38 3 Sie), — 0.29 9°4 61.57 4 2 | | | 144 THE DEPTHS OF THE SEA. (CHAP. III. | l oe Bree cries «| ore Eature. Position. | | 64 640) = eC. 9° 31, || Gil 21 Ne 3°44’ W. | 65 SA ae fled 61 10 Daik | 66 267 7:6 11°3 61 15 1 44 lente 64. 9-5 ibe 60 32 0 29 68 , 15 6°17 pie 4 60 °23 0 335) 69 67 6°5 12°50 60 1 |, O-niSaEE 70 66 pos tle -39 604. 1 eso se ul 7 103 9-2 11°6 60 17 | Das 72 76 9-4 ibe 3 60 20 3 5 73 84 9-4 fie 25 60 29 3 6 74 203 Enz tied! 60 39 3 9 75 250 5-5 10-8 60 45 3G 76 BAA se Sale al Oral 60 36 3 58 Ting 560 | 2 1075 60 34 4 40 rie 290 5-3 lees? 60 14 Ags 79 76 9-4 fi 2 59 44 4 44 80 7) Ogre al eeiuie Wey, ae aw aN S) ‘| 9, Y d \ f f ff oe Wa Z - Se/ y Ke =f Kt : ¢ ie) 4 or? (Owed ANS Fie. 27. -— Culveria hystriz, Wyv!Ltn TaHomson. Two-thirds the natural size (No. 86.) tainly in my case mingled with a certain amount of nervousness, when it settled down quietly in the form of a round red cake, and began to pant—a line of conduct, to say the least of it, very unusual in its rigid undemonstrative order. Yet there it was with all the ordinary characters of a sea-urchin, its inter- ambulaeral areas, and its ambulacral areas with their CILAP. IV. ] THE CRUISES OF THE ‘ PORCUPINE’ Love rows of tube feet, its spines, and five sharp blue teeth ; and curious undulations were passing through its perfectly flexible Jeather-like test. I had to summon up some resolution before taking the weird little monster in my hand, and congratulating myself on the most interesting addition to my favourite family which had been made for many a day. Calveria hystrix—for I have named this genus and species after our excellent Commander and his tidy Fie. 28.—Calveria hystrix, WyvILLE THomson. Inner surface of a portion of the test showing the structure of the ambulacral and interambulacral areas. little vessel, in grateful commemoration of the plea- sant times we had together —is circular and depressed, rather more than 120 mm. in diameter, and about 25 mm. high (Fig. 28). Both interambulacral and ambulacral areas are wide. The peristome and the periproct are unusually large ; the former covered with calcareous scale-like plates, perforated up to the rim of the mouth for the passage of ambulacral tube-feet, as in Cidaris ; the latter with a large madreporic tubercle 158 THE DEPTHS OF THE SEA. [CHAP. Iv. and five large round openings in the ovarial plates in the centre of which open the wide ducts from the ovaries. The jaw pyramid, ‘Aristotle’s lantern,’ is large and strong, and formed on the pian of the Dia- dematide, and the teeth are large and simply chan- nelled. The point of structure, however, in which Calveria differs from all previously described recent urchins is the arrangement of the ambulacral and interambulacral plates. These, instead of meeting edge to edge and abutting against one another so as to form a continuous rigid shell as in most other echinids, overlap one another ; the plates of the inter- ambulacral areze from the apical pole towards the mouth, those of the ambulacral areze from the mouth towards the apical disk (Fig. 28). In Calveria, the outer portions of the interambulacral plates leave spaces between them which are filled up with mem- brane, and the inner ends of the plates form large wide expansions, which overlap greatly. The ambulacral pairs of pores are singularly arranged: they are in ares of three, but two of the pairs of each arc penetrate small special accessory plates, while the third pair penetrates the ambulacral plate near the end. The outer ends of the interambulacral plates overlap the outer ends of the ambulacral plates, so that the ambulacral ares are essentially within the interambu- lacral. The interambulacral plates bear each close to the outer end where they overlap the ambulacral plates, a large primary tubercle ; and two imperfect rows of primary tubercles bearing long spines are ranged in the middle of the ambulacral arew; the remainder of the surface of the plates is thickly studded with secondary tubercles and miliary grains. CHAP. 1V.] THE CRUISES OF THE ‘PORCUPINE, 159 The spines are very delicate and hollow, with pro- jecting processes arranged in an imperfect spiral; and resemble somewhat the small spines of the Diade- matide. The colour of the test is a rich crimson with a dash of purple, and it is very permanent; the only perfect specimen procured which is preserved in spirit has not lost colour greatly to the present time. In the summer of 1870, Mr. Gwyn Jeffreys, dredging on the coast of Portugal, took two nearly perfect specimens and several frag- ments of another species of the genus Calveria; and subsequent careful examination of fragments and débris has shown that this second species, C. fenestrata, occurs likewise in the deep water off the coast of Scotland and Ireland. The interambulacral plates are nar- rower, and leave larger membra- nous spaces between them, and the great key-like overlapping expan- sions in the middle line are much larger. The spines have the same FP iN form and are arranged nearly in | Nige he aioe the same way; but parallel to fyyueDiieliccnuie the outer row of large spines on each interambulacral space there is a row of four or five or more pedicellariw, of quite a peculiar type. The head of the pedicellaria, which is supported on a long stalk, consists of four valves (Fig. 29), the wide terminal portion of each forming “160 THE DEPTHS OF THE SEA. [CHAP. Iv. a beautiful double fenestrated frame, with a peculiar twist in it reminding one of a Campylodiscus, and a very elegant crenated border. ‘These disks are raised on delicate hollow pedicels, which expand beneath, at their point of attachment to the common stalk. A large mass of muscle envelopes the lower part of the group of pedicels, and doubtless determines the movement of the valves in reference to one another. It is difficult to see what relation in position the valves can occupy when the instrument, whatever may be its use, is closed. We now steamed onwards to the south-east for about ten miles, and put down our dredge, fully equipped with ‘ hempen tangles’ and every accessory device for entrapping the denizens of the deep, exactly, as our Commander assured us, over the spot where we had dredged the ZHolteniw early in the cruise. We vot there in the evening, and adopted a plan which we had tried successfully once or twice before; we allowed the dredge to remain down all night, moving along with the drift of the vessel, and hauled it up in the early morning. I do not believe human dredger ever got such a haul. The special inhabit- ants of that particular region—vitreous sponges and echinoderms—had taken quite kindly to the tangles, warping themselves into them and sticking through them and over them, till the mass was such that we could scarcely get it on board. Dozens of great Hol- tenia, like ‘“‘Wrinkled heads and aged, ‘With silver beard and hair,” a dozen of the best of them breaking off just at that critical point where everything doubles its cuap.iv.]) THE CRUISES OF THE ‘PORCUPINE: 164 weight by being lifted out of the water, and sink- ing slowly away back again to our inexpressible anguish ; glossy whisps of Myalonema spicules; a bushel of the pretty little mushroom-like 7isiphonia ; a fiery constellation of the scarlet Astropecten tenwis- pinus ; while a whole tangle was ensanguined by the ‘disjecta membra’ of a splendid Brisinga. There was not much in the dredge-bag that was new. Some large Munide, with their ‘ sphéery eyne; ’ some fine specimens of Kophobeleninon milleri; an example of the Euryalid, Asteronyx lovén’, nearly the only Scandinavian echinoderm which we had not previously taken ; and an injured specimen of a flexible urchin, which we supposed to be of the same species as that procured the day before, although it differed greatly in colour, being of a uniform pale grey. Upon further examination, however, it proved to be the type of a totally different generic group of the same family. Phormosoma placenta resembles Calveria in having the perisom flexible, the plates overlapping in the same way and in the same directions; but the plates overlap one another only slightly, and they leave no membranous spaces between, so that they form a continuous shell. The great peculiarity of this form is that the upper surface is quite different from the lower. Above, the ambulacral and interambulacral areze are well defined and in ordinary proportion, the interambulacral areze being just twice as wide as the ambulacral, and the spines are much like those of Calveria, and are arranged nearly in the same manner. At the periphery the shell comes to a kind of ridge, and alters entirely; from the edge M 162 THE DEPTHS OF THE SEA. (CHAP, Iv. to the mouth the distinction between ambulacral and interambulacral areze is apparently lost, and the sutures between the plates can scarcely be made out; the pore ares are reduced to mere lines of double pores, and the whole of the surface of the shell is studded over uniformly with the very large areole: of primary tubercles, bearing spines which are small and delicate and apparently quite out of proportion to the mass of muscle connected with them which fills the areole. As in Calveria, the tubercles are perforated. We have thus become acquainted with three mem- bers of a family of urchins which, while differing in a most marked way from all other known living eroups, bear a certain relation to some of these, and easily fall into their place in urchin classification. They are ‘regular echinids,’ and have the normal number and arrangement of the principal parts. They resemble the Cidaridee in the continuation of the lines of ambulacral pores over the scaly membrane of the peristome to the mouth, and they approach the Diadematidée in their hollow spines, in the form of their small pedicellariz, and in the general structure of the jaw pyramid. From both of these families they differ in the imbricated arrangement of the plates and in the structure of the pore aree, to the widest extent compatible with belonging to the same sub-order. Many years ago Mr. Wickham Flower of Park Hill, Croydon, procured a very curious fossil from the upper chalk of Higham near Rochester. It con- sisted of a number of series of imbricated plates radiating from a centre, and while certain sets of these plates were perforated with the characteristic double CHAP. Iv. ] THE CRUISES OF THE ‘ PORCUPINE,’ 163 pores of the urchins, these were absent in alternate series. Some points about this fossil, particularly the imbricated arrangement of the plates over portions indicating a circle at least four inches in diameter, caused great difficulty in referring it to its place. Edward Forbes examined it, but would not hazard an opinion. The general impression was that it must be the scaly peristome of some large urchin, possibly of a large Cyphosoma, a genus abundant in the same bed. Some years after the discovery of the first specimen, a second was obtained by the Rev. Norman Glass, from Charlton in Kent. This specimen ap- peared at first to solve the difficulty, for it contained in the centre a well-developed ‘lantern of Aristotle; ’ there then was the peristome of the urchin, of which Mr. Flower’s specimen was the periproct. The late Dr. 8S. P. Woodward examined the two specimens carefully, and found that the question was not so easily settled. J1e detected the curious reversal of the imbrication of the plates in the ambulacral and interambulacral ares which I have described in Calveria, and at one point he traced the plates over the edge of the specimen, and found that they were repeated inverted on the other side. With great patience and great sagacity he worked the thing out, and came to the conclusion that he was dealing with the representative of a lost family of regular echinids. Woodward names his new genus Lehinothuria, and describes the chalk species, /. floris, almost as fully and accurately as we could describe it now with a full knowledge of its relations—for Lchinothuria is closely related to Calveria and Phormosoma. In all M 2 164 THE DEPTHS OF THE SEA. [CHAP. IV. essential family characters they agree. The plates imbricate in the same directions and on the same plan, and the structure of the ambulacral arez, which is so special and characteristic, is the same. Echinothuria differs from Calveria in the wider inter- ambulacral and ambulacral plates, in the smaller amount of overlapping, and in the absence of mem- branous intervals; and from Phormosoma it differs in having the structure and ornament of the apical and oral surfaces of the test the same. As the genus Hehinothuria was the first deseribed, I have felt justified in naming the family the Echino- thuridee. I have done this with the greater pleasure, as it brings into prominence a term suggested by my late friend Dr. Woodward, whose early death was a serious loss to. science. In Dr. Woodward’s memoir, the following curious paragraph occurs :— ‘After this apparently conclusive demonstration, it appears desirable to give a name to this fossil and to attempt a short description, although its rank and affinities are still a matter of conjecture. At present it is one of those anomalous organisms which Milne Edwards compares to solitary stars belonging to no constellation in particular. The disciples of Von Baer may regard it as a ‘ generalized form’ of echinoderm, coming, however, rather late in the geological day. The publication of it should be acceptable to those who base their hopes on the ‘imperfection of the geological record,’ as it seems to indicate the former existence of a family or tribe, whose full history must ever remain unknown.” The special bearings of the discovery of this group, and of several other animal forms allied to chalk fossils CHAP. IV. | THE CRUISES OF THE ‘ PORCUPINE’ 165 living among the recent chalk-mud of the Atlantic sea-bed, will be discussed in a future chapter. While we were examining our wonderful dredge- load the little ‘ Porcupine’ was steaming slowly southwards—past the island of Rona, and Cape Wrath looking out into the north cold and blue, with the waves now curled up asleep at its feet, as if they never did any harm; past the welcome Butt of the Lews, and into the little harbour of Stornoway. Here we remained some days; not sorry—even although our cruise had been thoroughly pleasant—to exchange the somewhat cramped routine of life in a gun-boat for the genial hospitalities of Stornoway Castle. The fauna of the ‘warm area’ is under circum- stances altogether special and peculiar, which must be discussed in full hereafter. While the cold area is sharply restricted, the warm area extends con- tinuously from the Féroes to the Strait of Gibraltar. At all events the same conditions are continuous; but as will be explained more fully hereafter, the whole 600 or 700 fathoms of water down to the bottom at the mouth of the Féroe Channel, corre- sponds with the surface layer only to a like depth in the Rockall Channel or in the Atlantic basin. The first 700 to 800 fathoms in all cases are actually warm, but where the depth greatly exceeds 800 fathoms, there is a mass of cold water beneath sink- ing slowly to nearly the freezing-point. The bottom therefore, the habitation of the fauna, is only warm where the depth is not greater than 800 fathoms, and in such a case only can the term ‘warm area’ be correctly applied. Such are the conditions off Feéroe, and it is this which makes the contrast 166 THE DEPTHS OF THE SEA. [cHAP. IV. between the warm and cold areas so marked in that region. The warm area, however, even as thus re- stricted, is continuous southwards so far as we know indefinitely for the North Atlantic, occupying the zone of depth along the coast from say 300 to 800 fathoms. At great depths everywhere the climatal conditions approach those of the cold area, and the actual character of a fauna—an assemblage of animals at any one spot—must depend not merely upon tem-_ perature but upon the laws regulating the distribu- tion of deep-sea animals; a subject on which we know as yet very little. The bottom in the cold area in the F#roe Channel is rough gravel. That in the warm is everywhere nearly homogeneous ‘ globigerina ooze.’ This cir- cumstance alone is sufficient to determine a marked difference in the habits of the animals and their mode of life. Referring then to the foraminifera, the dredge came up throughout the warm area full of Globigerina and Orbulina, and fine calcareous mud, the product of their disintegration. Among these were multitudes of other forms, most of them of large size. I quote from Dr. Carpenter. Speaking of the Holfenia ground, he says:—*The Foraminifera obtained on this and the neighbouring parts of the warm area presented many features of great interest. As already stated, several arenaceous forms (some of them new) were extremely abundant; but in addition to these we found a great abundance ef Iiliolines of various types, many of them attainimg a very unusual and some even an unprecedented size. As last year, we found Cornuspire resembling in general aspect the large CHAP, IV. ] THE CRUISES OF THE ‘ PORCUPINE, 167 Operculine of tropical seas, and Biloculinew and Triloculine far exceeding in dimensions the littoral forms of British shores; and with these were asso- ciated Cristellarie of no less remarkable size, pre- senting every gradation from an almost rectilineal to the nautiloid form, and having the animal body in so perfect a state as to enable it to be completely isolated by the solution of the shell in dilute acid.” Sponges were extremely abundant, but they were restricted to only a small number of species; all of them with one form or another of the curious an- choring habit. Among the Hexactinellide Holtenia was the most striking and the most abundant form. Hyalonema was also common; but we got few per- fect specimens with the sponge and glass-rope in connection. ‘The conical sponge heads were very numerous; they seemed to have been torn off by the edge of the dredge, the rope remaining in the mud, and the ropes were frequently brought up without the sponge. Almost all the ropes were encrusted with the constant ‘commensal’ of Hya- lonema, Palythoa fatua. Very young examples of Hyalonema, with the whisp from 5 mm. to 20 mi. long, had usually no Pylathoa on them; but when they had attained above the latter dimensions in almost every case one could see the first polyp of the Palythoa making its appearance as a_ small bud, and its pink-encrusting ccenosarc spreading round it. By far the most common sponge in the chalk-mud is the pretty little hemispherical corti- eate form Tisiphonia agariciformis. This~ species, though differing from it greatly in appearance and habit, seems to be closely ailied to a strong, heavy 168 THE DEPTHS OF THE SEA. [CHAP. IV. encrusting sponge which we met with frequently sticking to stones in the ‘cold area.’ The form of the spicules was nearly though not quite the same, and their arrangement was very similar. It appeared as if the two forms placed in intermediate cireum- stances might have approached one another very closely. In the warm area, as in the cold at these great depths, there is a singular absence of Hydrozoa, A few species of Serfularia and Plumularia, and one or two allied forms occurred, and they are now in the skilful hands of Dr. Allman for determination ; but their small number and insignificance is remarkable. Neither are the true corals represented by numer- ous species, although in some places individuals are enormously abundant. During the ‘ Porcupine’ cruises of 1869 twelve species of Madreporaria were procured which have been determined by Professor Martin Duncan. None of these belong to ‘reef- building’ genera, but to a group which are recog- nized as deep-sea corals, a group which appears to have had numerous representatives during all the later eeological periods. In a band somewhat restricted in depth, extending downwards from the 100-fathom line, we met in some places with very large numbers of many varieties of Caryophyllia borealis, FLEMING (Fig. 4); and at depths of 800 to 600 fathoms the handsome branching Lophohelia prolifera, PALAs (Fig. 30), forms stony copses covering the bottom for many miles, the clefts of its branches affording fully appreciated shelter to multitudes of Arca nodulosa, Psolus squamatus, Ophiopholis aculeata, and other indolent ‘ commensals.’ CHAP, IV. | THE CRUISES OF THE ‘ PORCUPINE,’ 169 Five species of Amphihelia are cited by Professor Martin Duncan from the ‘ Porcupine’ expedition :— A. profunda, Pourraues ; A. oculuta, L. sp.; A. mio- cenicd, SEGUENZA ; A. allantica, n. sp.; and A. ornata, Lic. 30.—Lophohelia prolifera, PALLAS (sp.). Three-tourvus tue natural size. (No 26.) n. sp.; and on one or two occasions, chiefly on the verge of the cold area, the henapen tangles involved some elegant fragments of the stony coral Allopora oculina, EHRENBERG (Fig. 31), 170 THE DEPTHS OF THE SEA. [CHAP, TV, Although many of the echinoderms of the cold area are common to the warm, the general facies of the echinoderm fauna is different, and there are a number of additional and very striking forms. Cidaris papillata, LESKE, is abundant at moderate Fig 31.—A llopora rculina, EHRENBERG. depths. On our second visit to the Holtenia ground we dredged one small specimen of the handsome urchin already described, Porocidaris purpurata. A fine brilhantly-coloured urchin of the Lchinus CHAP. IV. ] THE CRUISES OF THE ‘ PORCUPINE’ iA flemingii group, but distinguished from LE. flemingii by characters which I must regard as of specific value, Hehinus microstoma, WYVILLE THOMSON, was common and of large size; and along with it many very beautiful brightly-coloured examples of the smallest form of L. norvegicus. The three species of the Echinothuride, Calveria hystrix, C. fenestrata, and Phormosoma placenta have as yet been met with in this region only, and they seem to have a wide distribution, stretching at about the same depth and temperature from the Féroe Islands to the south of Spain. I hear from Pro- fessor Alexander Agassiz that Count Pourtales has dredged fragments of one of the species under nearly similar circumstances in the Strait of Florida. Cribrella sanguinolenta was in thousands, of all colours—scearlet, bright orange, and chocolate brown. Several examples were found of a fine Scytaster, probably identical with the Asterias caneriensis of D’Orbigny, and if so having a southern distribu- tion. The curious little Pedicellaster typicus of Sars was not unfrequent ; a form which looks very much like the young of something else. One small specimen of Péeraster militaris came up from the Holtenia ground, but with the exception of Aséyo- pecten tenuispinus, which seemed to be more abun- dant than ever, the characteristic aretic echino- derms were absent. We took no examples here of Toxopneustes drobachiensis, Tripylus fragilis, -Ar- chaster andromeda, Clenodiscus crispatus, Astropecten arcticus, Huryale linkii, Ophioscolex glacialis, or Antedon escrichtii. It is very likely that there may be colonies in the ‘ warm area’ of some or of all of 1/2 THE DEPTHS OF THE SEA, [cHAP, 1V. these—for the region in which they are common under very different climatal conditions is within a few miles, and there is no intervening barrier—but Fic. 32.—Ophiomusium lymani, WYVILLE THOMSON. Dorsal surface ; natural size. (No. 45.) they certainly are not abundant. Amphinra abys- sicola, SARS, was in great numbers sticking to the sponges, and Ophiacantha spinulosa was nearly as common as in the cold area. CHAP. IV. ] THE CRUISES OF THE ‘ PORCUPINE, as We took one or two small examples of a very fine ophiurid, of which larger specimens had been pre- viously found at about the same depth and tem- perature during the second cruise of the same season off the coast of Ireland. This form probably ought to be referred to Lyman’s genus Ophiomusium, Fic. 33.—Ophiomusium lymani, WYVILLE THomson. Oral surface. though the characters of the genus must be some- what altered to admit it. Ophiomusium eburneum, LyMAN, of which several specimens were taken by Count Pourtales at depths of from 270 to 335 fathoms, off Sandy Key, is distinguished by the great solidity and complete calcification of the 174 THE DEPTHS OF THE SEA. [cHAP. Iv. perisom. The plates of the disk are soldered together, so as to form a close mosaic (vceiov). The mouth-papille are fused into two lines, their number being only indicated by grooves. The lateral arm-plates are united together above and below, the upper and lower arm-plates are reduced to mere rudiments, and there are no tentacle pores beyond the first arm-joints. Fa. 34.—Dorynchus thonsoni, NORMAN. Once and a half the natural size ; everywhere in deep water, In our new species, which I name provisionally Ophiomusium lymani, the diameter of the disk is 28 mm., and the length of each arm 100 mm. in large specimens. The two lateral arm-plates, fused together above and below, form complete rings, their distal edge notched on each side for the insertion of seven arm spines, of which the lowest is much longer than the rest. The dorsal arm-plates are small and diamond-shaped, let in between the lateral arm- plates at the distal end of their upper line of cuar.1v.] THE CRUISES OF THE ‘PORCUPINE’ 175 junction. The ventral arm-plates are entirely absent. This is a large handsome star-fish. I am not aware of any fossil form which can be referred to the same genus; but it looks like a. thing which might be expected to have congeners in the upper chalk. Holothurids were not frequent, but the singular little Lchinocucumis typica of Sars, covered with spiny plates, turned up in every sifting. Fig. 35.—Amathia carpenteri, NorMAN. Once anda half the natural size. (No. 47. Crustacea are numerous ; but we have here entirely lost the gigantic Arctic amphipods and isopods of the ‘cold area.’ A pretty little stalk-eyed form Dorynchus thomsoni, NorMAN (Fig. 34), small and delicate, and very distinct from all previously de- scribed species of the genus, is very widely diffused. lea THE DEPTHS OF THE SEA. [CHAP. lV. This crab, from its long spiny legs and light body, very often comes up entangled on the part of the rope which had been passing over the ground. Another handsome new species, Amathia carpenteri, NORMAN (Fig. 35), was common in the sandy chalk-mud of the ‘Holtenia ground.’ The genus had previously been familiar as a Mediterranean form. 7 I quote from a preliminary notice of the Crus- tacea by the Rev. A. Merle Norman: ‘“ Ethusa granulata (sp. n.), the same species as that found off Valentia, but exhibiting a most extraordinary modification of structure. The examples taken at 110—370 fathoms in the more southern habitat have the carapace furnished in front with a spi- nose rostrum of considerable length. The animal is apparently blind, but has two remarkable spiny eye-stalks, with a smooth rounded termination where the eye itself is ordinarily situated. In the specimens however from the north, which live in 542 and 705 fathoms, the eye-stalks are no longer moveable. They have become firmly fixed in their sockets, and their character is quite changed. They are of much larger size, approach nearer to each other at their base, and instead of being rounded at their apices they terminate in a strong rostrate point. No longer used as eyes, they now assume the functions of a rostrum; while the true rostrum so conspicuous in the southern specimens has, marvellous to state, become absorbed. Had there been only a single example of this form procured, we should at once have concluded that we had found a monstrosity, but there is no room for such an hypothesis by which to escape from this most strange instance of modifi- CHAP. 1V.] THE CRUISES OF THE ‘PORCUPINE, Ari eation of structure under altered conditions of life. Three specimens were procured on two different occasions, and they are in all respects similar. Mollusca are much more abundant and varied in the warm area than in the cold. Mr. Gwyn Jeffreys remarks, however, that there is not such a decided difference in the Molluscan fauna of the two regions as might have been expected from the difference in their conditions; very many species being common to both. At 500 fathoms the sponges are full of Pecten vitreus, CHEM., and Columbella halieti, JEFFREYS; and throughout the area species occur of many Molluscan genera, including Lima, Dacridium, Nucula, Leda, Montacuta, Axvinus, Astarte, Tellina, Neawra, Dentalium, Cadulus, Siphonoden- talium, Rissoa, Aclis, Odostomia, Aporrhais, Pleuro- toma, Fusus, and Buccinwin. Taken as a whole the fauna of the warm area off the north of Scotland seems to be an extension of a fauna with which we are as yet very imperfectly acquainted, occupying what we must now call moderate depths, say from 300 to 800 fathoms, along coasts which are bathed by currents of equa- torial water. The fauna of this zone is evidently extremely rich; and as it is beyond the reach of ordinary dredging from an open boat, and yet not at_ a sufficient depth to present any very great diffi- culty from a yacht of average size, its exploration seems to present just the combination of adventure and novelty to stimulate amateurs; so we may hope shortly to have its conditions and distribution cleared up. A most successful step in this direction has been made already by Mr. Marshall Hall, who N 178 THE DEPTHS OF THE SEA. [CHAP. IV. with his yacht ‘Norna,’ and with the aid of Mr. Saville Kent, has thrown a good deal of additional light upon the zoology of the ‘warm area’ off the coast of Portugal. We left Stornoway on the 18th of September, and in the afternoon dredged for a few hours in Loch Torridon without much result. Late in the evening, steaming down Raasay Sound, we came upon the luminous forest of Pavonaria to which I have already referred. At noon, on the 14th, we were abreast of the Island of Mull, and on the 15th we were once more moored in the Abercorn Basin, Belfast, where we took leave of the ‘ Porcupine’ and our highly- valued friends her captain and officers; in the hope of meeting them again shortly, and thoroughly satisfied with the success of our summer’s work. On the 24th of March, 1870, a letter was read at the council meeting of the Royal Society from Dr. Car- penter, addressed to the President, suggesting that an exploration of the deep sea, such as was carried out during 1868 and 1869 in the regions to the north and west of the British Islands, should now be extended to the south of Europe and the Mediterranean, and that the council of the Royal Society should recom- mend such an undertaking to the favourable con- sideration of the Admiralty, with a view to obtain the assistance of Her Majesty’s Government, as on the previous occasions. ‘The official correspondence, with reference to the expedition of the summer of 1870, is given in Appendix A to the present chapter. ft was intended, as on the previous occasion, to divide this year’s expedition into cruises; and again Mr. Gwyn Jeffreys undertook the scientific direction cHapP. Iv.] THE CRUISES OF THE ‘ PORCUPINE, 179 of the first cruise, at a time when both Dr. Carpenter and I were occupied with our official work. A young Swedish naturalist, Mr. Joshua Lindahl of the Uni- versity of Lund, accompanied him as zoological assistant, and Mr. W. L. Carpenter took charge of the chemical department. It was arranged that Mr. Jeffreys’ cruise should extend from Falmouth to Gibraltar. Dr. Carpenter and I were to have re- heved him at Gibraltar, meeting the vessel there, and to have worked together as we did the year before; but I was unfortunately laid up with an attack of fever, and the whole charge of the last cruise in the Mediterranean rested with Dr. Carpenter. Owing to this untoward circumstance, I must give at second- hand the brief account of the first part of the work of the year 1870 which is necessary to complete the sketch of what has been done towards the illus- tration of the condition and fauna of the North Atlantic. In the Mediterranean Dr. Carpenter found the conditions of temperature and of the distribu- tion of animal life entirely exceptional, as might have been to a certain extent anticipated from the exceptional circumstances of that land-locked sea. The investigation of 1870 can only be said to have broken ground towards the solution of a series of very special and peculiar problems; and I am not in a position to go farther at present than to indicate the general results at which my colleague has arrived. The ‘ Porcupine’ left Falmouth on the 4th of July, but was detained in the Channel for several days by fogs and contrary winds. On the 7th of July, they reached the slope from the plateau of the Channel to the deep water of the Atlantic, and took a first haul N 2 180 THE DEPTHS OF THE SEA. [CHAP. IV. in 567 fathoms. Mr. Jeffreys reports the contents of the dredge as small but very interesting. Among the mollusea he notes Terebratula septata, Limopsis borealis, Hela tenella, Verticordia abyssicola, Turbo filosus, and Ringicula ventricosa. Turbo filosus and its variety 7. glabratus had previously been known only as fossils in the tertiaries of Calabria and Mes- sina. Terebratula septata, Limopsis borealis, and ITela tenella are likewise fossil in the Pliocene beds of southern Italy, and are found living in the Scandi- navian seas. Mr. Norman notes among the crus- taceans new species of Ampelisca and of six other genera; and the beautiful scarlet Echinus microstoma was the most conspicuous echinoderm. The wind, as the vessel passed over the slope of the Channel, was rather too light for successful dredging : the drift-way was scarcely sufficient to carry the dredge along. The tangles were most valuable, coming in as highly effective aids, particularly in securing all things provided with anything in the form of spines or other asperities. On the 8th the first haul was nearly a failure. Other hauls later in the day, at 690 and 500 fathoms, gave important results. Rhynchonella sicula, SEGUENZA ; Pleuronectia, sp. n.; and Acteon, sp. n., occurred : besides the usual northern species. Mr. Norman reports as to No. 3: ‘A most important dredging, the results among the crustacea being more valu- able than all the rest put together—at any rate of the first cruise. It contains almost all of the choicest of the new species in last year’s expedi- tion, and four stalk-eyed crustaceans of great in- terest, three of which are new, and the fourth, PLATE V.— Tract 0 = 7 | IRELAND Cort Valentiac/| 7 . |Z at US. Porcupine "1870; S vy Guernsey to Jersey Q © OUshant * a eae Betle ie — > E FIRANCE ° ° = ® s = x wo Rex Oleron\\ see . Nee. > Trieste Bordeaux | ae 4 j os) CF inisterre EF ¢ A 7 ; Str of Bont = bled | ’ } i \ \ corsic ; i 1 ' : \ iY \ iy 4 \ ' 1 1 1 ‘ ' \ \ Lisbon 4 eo Lspichel ! /#N6o Fae: . ‘o vA \. (Linosa SS Matta > > ae ‘ of Lampeduse.. S rum 4 : eee > - =. 22 * >’ - = * - , ‘ ate CHAP. IV. |} THE CRUISES OF THE ‘ PORCUPINE, 181 Geryon tridens, is a fine Norwegian species. With these are associated two forms of a more southern character, Znachus dorsettensis and Hbalia cranchii, which I should not have expected at so great a depth.” The echinoderms were a very northern group. They included Cidaris papillata, Echinus nor- vegicus and EF. microstoma, the young of Brissopsis lyrifera, Astropecten arcticus, Archaster andromeda, and A. parellii, with a small specimen of Ophio- musium lymani, several examples of Ophiacantha spinulosa, and as usual one or two of the universally distributed Eehinocucumis typica. Dr. McIntosh, to whom the annelids were referred, notices as a species supposed to be specially northern, Thelepus coro- natus, Fas.; and Holtenia carpenteri, our familiar anchoring sponge, of all sizes and ages and in consider- able numbers, was entangled in the hempen ‘ swabs.’ July 9th.—The wind still too light for effective work. Dredged in 717 and 358 fathoms, the assem- blage of mollusca having the usual character of being to a great extent common to the recent fauna of the seas of Norway and to the plocene fauna of Sicily and the Mediterranean. It included on this occasion Terebratella spitzbergensis, an arctic and Japanese form, Pecten vitreus, and P. aratus, Leda pernula, Trochus suturalis, Odostomia nitens, and Pleurotoma hispidulum. Among the echinoderms was a_ fine specimen of Brisinga endecacnemos, ABSJORNSEN, very markedly different from B. coronata, which was the form commonly met with in the north. The corals were represented by Amphihelia oculata and Desmophyllum crista-galli. Among the annelids were Pista cristata, O. F. Mtruur, and Trophonia glauca, eS THE DEPTHS OF THE SEA. [ CHAP. Iv. MatMGREN, both of them Arctic species. ‘The LOth was Sunday, and the vessel lay-to, and on the 11th they dredged, still on the slope of the channel plateau, with nearly the same result as before, the fauna maintaining the same character. Mr. Gwyn Jeffreys was now anxious to get a haul or two in the very deep water off the mouth of the Bay of Biscay, which we had explored successfully in 1869. ‘They therefore steamed southwards, going a considerable distance without dredging, as they were afraid of coming in contact with the cable between Brest and North America. When they got to their ground unfortunately bad weather set in, and they were obliged to make for Vigo. On Thurs- day, July 14th, they passed Cape Finisterre, and dredged in 81 fathoms about 9 miles from the Spanish coast. Along with a number of familiar forms, some of them with a wide northern exten- sion, they here took on the tangles two specimens, one young and one apparently mature, both con- siderably injured, of the singular Echinidean already mentioned, Calveria fenestrata. This is evidently not a rare form, nor is it confined to very deep water ; it is rather remarkable that it should have escaped notice so long. On the 15th, they sounded in from 100 to 200 fathoms, about 40 miles from Vigo, and on the 16th took one or two hauls in Vigo Bay at a depth of 20 fathoms. This locality had already been well-nigh exhausted by Mr. McAndrew in 1849, and only a few additions were made to his list. They left Vigo on the 18th. I quote from Mr. Gwyn Jeffreys :— ‘“* Wednesday, July 20th—Dredged all day with CHAP. IV. ] THE CRUISES OF THE ‘ PORCUPINE’ 183 considerable success at depths from 380 to 994 fathoms (Stations 14-16): the wind and sea had now gone down; and we took with the scoop-net a few living specimens of Clio cuspidata. ‘The dredgings in 380 and 469 fathoms yielded among the mollusca Leda lucida (Norwegian and a Sicilian fossil), Axinus eumyarius (also Norwegian), Newra obesa (Spitz- bergen to the west of Ireland), Odostomia, n. sp., O. minuta (Mediterranean), and Cerithinm, n. sp.; and among the echinoderms were Brisinga endecacnemos and Asteronyx lovént. But the results of the dredg- ing in 994 fathoms were so extraordinary as to excite our utmost astonishment. It being late in the even- ing, the contents of the dredge could not be sifted and examined until daylight the next morning. We then saw a marvellous assemblage of shells, mostly dead, but comprising certain species which we had always considered as exclusively northern, and others which Mr. Jeffreys recognized as Sicilian tertiary fos- sils, while nearly 40 per cent. of the entire number of species were undescribed, and some of them repre- sented new genera. The following is an analysis of the mollusca perfect and fragmentary taken in this one haul : — Orders. | ated | Recent. | — Fossil. Unde | of Species. Brachiopoda. . . . i 1 — = MeConchifera. . . . . 50 32 1 17 | Solenoconchia . . . 7 3 == 4 | Gasteropoda. . . . Les 42 23 48 | Fieteropoda ~ . . *. | 1 1 — aa Meetcropoda. ~. . . .. | I4 12 — 2 roche | 186 91 24 71 184 THE DEPTHS OF THE SEA, [CHAP. IV. The northern species above referred to are 34 in num- ber, and include Dacridium vitreum, Nucula pumila, Leda lucida, L. frigida, Verticordia abyssicola, Neewra jugosa, N. obesa, Tectura fulva, Fissurisepta papillosa, Torellia vestita, Pleurotoma turricula, Admete viridula, Cylichna alba, Cylichna ovata, JEFFREYS n. sp., Bulla conulus, 8. Woop not DrEsHayes (Coralline Crag), and Scaphander librarius. Leda lucida, Newra jugosa, Tectura fulva, Fissurisepta papillosa, Torellia vestita, as well as several other known species in this dredging, are also fossil in Sicily. Nearly all these shells, as wells as a few small echinoderms, corals, and other organisms, had evidently been transported by some current to the spot where they were found ; and they must have formed a thick deposit similar to those of which many tertiary fossiliferous strata are composed. It seemed probable also that the deposit was partly caused by tidal action, because a fragment of Melam- pus myosotis (a littoral pulmonibranch) was mixed with deep-water and oceanic Pectinibranchiates and Lamellibranchiates. None of the shells were Miocene or of an older period. “This remarkable collection, of which not much more than one-half is known to conchologists, not- withstanding their assiduous labours, teaches us how much remains to be done before we can assume that the record of Marine Zoology is complete. Let us compare the vast expanse of the sea-bed in the North Atlantic with that small fringe of the coast on both sides of it which has yet been partially explored, and consider with reference to the dredging last men- tioned what are the prospects of our ever becoming acquainted with all the inhabitants of the deep CHAP. 1V.] THE CRUISES OF THE ‘ PORCUPINE,’ 185 throughout the globe! We believe, however, that a thorough examination of the newer Tertiaries would materially assist us in the inquiry; and such exami- nation is feasible and comparatively easy. Much good work has been done in this line; but although the researches of Broecchi, Bivona, Cantraine, Phi- lippi, Calcara, Costa, Aradas, Brugnone, Seguenza, and other able paleeontologists in the south of Italy have extended over more than half a century, and are still energetically prosecuted, many species of molluscous shells are continually being discovered there, and have never been published. Besides the Mollusca in this dredging from 994 fathoms, Pro- fessor Duncan informs us that there are two new genera of corals, and /labellum distinctum, which last he regards as identical with one from North Japan. It coincides with the discovery on the Lusitanian coasts of two Japanese species of a curious genus of Mollusea, Verticordia, both of which are fossil in Sicily and one of them in the Coralline Crag of Suffolk.” In the same dredging there are a number of very singular undescribed sponges, many of them recalling some of the most marked characters of one of the sections of Ventriculates. ‘These will be referred to in a future chapter. On- Thursday, the 21st of July, dredging was carried on all day at depths from 600 to 1095 fathoms, lat. 39° 42’ N., long. 9°43’ W., with a bottom tempera- ture at 1095 fathoms of 4°°3C. and at 740 fathoms of 9°4C. The dredging was most successful ; many of the new and peculiar mollusca of the last dredging were taken here alive, with several additional forms. 186 THE DEPTHS OF THE SEA. [CHAP. IY. Several undescribed crustaceans were added ;—a new species of the genus Cenocyathus among the corals, and a species of an unknown genus allied to Bathy- cyathus. Brisinga endecacnemos and some new ophi- urids were part of the treasures, but the greatest prize was a splendid Pentacrinus about a foot long, of which several specimens came up attached to the tan- gles. ‘This northern Sea-lily, on which my friend Mr. Gwyn Jeffreys has bestowed the name Pentacrinus wyville-thomsoni, will be described hereafter with some other equally interesting members of the same group. Cape Espichel was reached on the 25th. The weather was now, however, so rough that Captain Calver was obliged to take shelter in Setubal Bay. Professor Barboza de Bocage of Lisbon had given Mr. Gwyn Jeffreys a letter of introduction to the coastguard officer at Setubal, who knew the place where the deep-sea shark and the Hyalonema are taken by the fishermen, but the state of the weather prevented his taking advantage of it. Off Cape Espichel in 740 and 718 fathoms, with a temperature of 10°:2 C., the mollusca were much the same as those from Station 16, but included Leda pusio, Limopsis pygmea (Sicilian fossils), and Verti- cordia acuticostata. ‘The last-named species is in- teresting in a geological as well as a geographical point of view. It is fossil in the Coralline Crag and the Sicilian Pliocene beds, and it now lives in the Japanese archipelago. Mr. Jeffreys suggests a mode of accounting for the community of so many species to the eastern borders of the Atlantic basin and the Mediterranean, in which several Japanese brachi- opods and crustaceans are found, and the seas of cHap. Iv.| THE CRUISES OF THE ‘PORCUPINE, 187 Northern Asia, by supposing a migration through Pie. 36.—Chondrocladia virgata, W\ VitLeE THomson. One-half the natural size. (No. 33, Pl. V.) the Arctic Sea. We must know, however, much 188 THE DEPTHS OF THE SEA. [cHAP. IV. more than we yet do of the extension both in time and space of the fauna of deep water before we can come to any certain conclusion on these questions. Dredging across the entrance of the Strait of Gib- raltar in 477, 651, and 554 fathoms, Stations 31, 32, and 33, with a bottom temperature of 10°38, 10° 1, and 10°0 respectively, many remarkable forms were dredged, including a very elegant sponge, apparently allied to, if not identical with, Oscar Schmidt’s Caminus vuleani, and some beautiful forms of the Corallio-spongize, which will be noticed in a future chapter. Station No. 31 yielded a sponge form which recalled the branching heather-like Cladorhiza of the cold area off Féroe. Chondrocladia virgata (Fig. 36) is a graceful branching organism from twenty to forty centimetres in height. A branching root of a cartilaginous consistence, formed of densely packed sheaves of needle-shaped spicules bound together by a structureless organic cement, attaches the sponge to some foreign body, and supports it in an upright position; and the same structure is continued as a solid axis into the main stem and the branches. The axis is made up of a set of very definite strands like the strands of a rope, arranged spirally, so as to present at first sight a strong resemblance to the whisp of Hyalonema ; but the strands are opaque, and break up under the point of a knife; and under the microscope they are found to consist of minute needle-like spicules closely felted together. The soft sponge substance spreads over the surface of the axis and rises into long curving conical processes, towards the end of which there is a dark greenish oval mass of granular sponge matter, and the outline of the CHAP. IV. |] THE CRUISES OF THE ‘ PORCUPINE, 189 cone is continued beyond this by a number of eroups of needle-shaped spicules which surround a narrow oscular opening. All parts of the sponge are loaded with triple-toothed ‘ bihamate’ spicules of the sarcode. On the 5th of August the ‘ Porcupine’ steamed into Tangier Bay, after ineffectually trying to dredge in 190 fathoms off Cape Spartel. In Tangier Bay two casts were taken at a depth of 35 fathoms. The fauna was chiefly British, with a few more southern forms. On the 6th of August Mr. Jeffreys went to Gib- raltar, and there yielded up the reins to Dr. Car- penter, going on to Sicily vid Malta, for the purpose of examining the newer tertiary formations in the south of Italy, and the collections of fossil shells at Catania, Messina, Palermo, and Naples, in connec- tion with the results of his cruise. On Monday, the 15th of August, Captain Calver, with Dr. Carpenter, who fortunately retained the services of Mr. Lindahl as assistant, in charge of the science department, steamed out into the middle of the Strait for the purpose of commencing a series of observations on the currents of the Strait of Gibraltar. These experiments, which at the time were not considered very satisfactory, were repeated and ex- tended in the summer of 1871 by Captain Nares, R.N., and Dr. Carpenter, in H.M.S. ‘ Shearwater.’ Their curious results have been given in great detail by Dr. Carpenter in the Proceedings of the Royal Society of London, and by Captain Nares in a special report to the Admiralty. As it is my purpose to 190 THE DEPTHS OF THE SEA. [CHAP. 1V. confine myself at present almost exclusively to the description of the phenomena of the deep water in the Atlantic so far as these have been worked out, 1 will not here repeat the narrative of the experiments in the Strait. I will, however, give a brief sketch of Dr. Carpenter’s cruise in the Mediterranean, as the remarkable phenomena connected with the distribu- tion of temperature and of animal life which he observed, illustrate while they contrast with the singularly different conditions which have been already described in the outer ocean. The first sounding in the basin of the Mediter- ranean was taken on the 16th of August, lat. 56° 0’ N., long. 4° 40’ W., at a depth of 586 fathoms, with a bottom of dark grey mud. The surface temperature was 23°6C., and the bottom temperature 12°8 C., about three degrees higher than at the same depth in the ocean outside. A serial sounding was taken to determine the rate of the diminution of temperature, with the following curious result :— Suntace<. akg de ao ee kt LOitathomisi) 9. 2a ee Re Le AOS 20 4 re ee ea es ook Por 30 se ee ee Toe et orm ent L/S) 40 2G 50 :; 6 100 “8 8 586 ‘ 2°8 Thus the temperature fell rapidly for the first 30 fathoms, more slowly for the next 20, from 50 to 100 lost only 3°C., and before reaching the depth of a hundred fathoms had obtained its minimum tempera- THE CRUISES OF THE ‘ PORCUPINE,’ 191 CHAP. I1V.] ture, there being no further diminution to the bottom. This serial sounding and all the subsequent tempera- ture observations taken during the Mediterranean cruise showed that the trough of the Mediterranean from the depth of 100 fathoms downwards is filled with a mass of water at almost exactly the same temperature throughout, a temperature a little above or below 12°-75 C. The following instances have been cited by Dr. Carpenter from the earlier observations in the Medi- terranean basin, to show the great uniformity of the bottom temperature for all depths :— Number | Depth Bottom Surface of in Tempera- Tempera- Position. Station. |Fathoms. ture. ture. ai | 730 | 13°40. | 23°-6C. | Lat 35°57’ N. |Long.4° 12’ w. | mee | #90 )13-2 | 23-2 | 35 45 Ny | 43 LOZ laa 23 °8 do 24 3 54 307 | 44 455 | 13-0 Oe s| 35 42 20” 3 00 30” 45 207 | 12-4 22 °6 39 20 LOM 2 29 30’ | 46 om ae) 23 -0 35 29 | 1 56 | 47 | 845 | 12-6 | 21-0 37 25 30” 1 10 30”| At this last Station (No. 47) a serial sounding was taken, which entirely confirmed the results of the first (No. 40) :— Surface . 10 fathoms 20Gs ae 30 40 50), 100 845 oo —o oD > or Ces — HS et bo bo Go S eo] =~ arm wm > re lap) 192 THE DEPTHS OF THE SEA. [cHAP. IV, a —again a mass of water lying at the bottom, 745 fathoms—not far from a mile—in depth, at the uniform temperature of 12°6C, (54°°7 F-.) The dredge was sent down at each successive station, but with very poor result; and Dr. Car- penter was driven to the conclusion that the bottom of the Mediterranean at depths beyond a few hundred fathoms is nearly azoic. The conditions are not actually inconsistent with the existence of animal life, for at most of the stations some few living forms were met with, but they are certainly singularly un- favourable. Thus at Station 49, at a depth of 1412 fathoms, and a temperature of 12°7 C., the following species of mollusca were obtained : Nucula quadrata, n. sp.; NV. pumila, ABSJORNSEN ; Leda, n. sp.; Verti- cordia granulata, SEG.; Hela tenella, JEFFREYS ; Trochus gemmulatus, Pu.; Rissoa subsoluta, ARADAS ; Natica affinis, GMELIN; Trophon multilamellosus, Pu.; Nassa prismatica, Br.; Columbella halieti, JEFF.; Bucciniwm acuticostatum, Pu.; Pleurotoma carinatum, CRISTOFORI and JAN; P. torquatum, PH. ; P. decussatum, PH. Near the African coast the fauna was more abun- dant, but the bottom was so rough that it was unsafe to use the dredge, and the tangles were usually sent down alone. Many polyzoa, echinoderms, corals, and sponges were taken in this way, but they were mostly well-known Mediterranean species. After remaining for a few days at Tunis and visiting the ruins of Carthage, dredging was resumed on the 6th of September on the ‘ Adventure’ Bank, so called from its having been discovered by Admiral Smyth when surveying in H.M.S. ‘Adventure.’ Here, at depths CHAP. IV. } THE CRUISES OF THE ‘ PORCUPINE,’ 193 from 30 to 250 fathoms, animal life was tolerably abundant. With other mollusca the following were found :—Trochus suturalis, Pu. (Sicilian fossil) ; Aenophora crispa, Kone (Sic. fossil) ; Cylichna striatula, ForBrEs (Sic. fossil); C. ovulata, Broccut (Sic. fossil); Gadinia excentrica, TrpERI; Scalaria Srondosa, J. Sowrersy (Sicilian and Coralline Crag fossil); Pyramidella plicosa, BRonNn (Sic. and Cor. Crag fossil); Actwon pusillus, ForBxs (Sic. fossil). The Echinodermata were abundant so far as indi- viduals went, but the number of species was small, and they were nearly all well-known Mediter- ranean forms. Cidaris papillata, Leskr, showing many varieties, but differing in no specific character from the many forms of the same species which range from North Cape to Cape Spartel in the ocean outside. The Mediterranean varieties of this species are certainly Ciduris hystrix, of Lamarck. I feel a degree of uncertainty about the pretty little Cidaris, described by Philippi under the name of C. affinis. Characteristic examples of it, which are abundant on the ‘Adventure’ Bank and along the African coast, look very distinct. They are of a beautiful deep rose red, the spines are banded with red and brownish-yellow, and come to a fine point, while those of C. papillata are usually blunt at the point, and frequently even a little expanded or cupped; and the portion of the interambu- lacral plates covered with miliary granules is wider, and two defined rows of body spines nearly of equal size lie up against the bases of the primary spines, over the alveole. These would appear to be cha- racters of specific value, but then again there are O 194 THE DEPTHS OF THE SEA. [craP. IV. a mass of intermediate forms; and although after careful consideration I have described the two species as distinct, I find it a matter of great diffi- culty to draw the line between them. Several specimens of a handsome Astrogonium allied to A. granulare were taken on the ‘ Adventure’ Bank. Professor Duncan reports some interesting corals, and Professor Allman two new species of Aglaophenia ; and Dr. Carpenter detected once more the delicate Orbitolites tenuissimus, and the large nautiloid Litwola, with which he was familiar in the dredgings in the Atlantic. After a short stay at Malta, on September 20th the ‘Porcupine’ steamed out of Valetta Harbour, and steered in a north-easterly direction, towards a point seventy miles distant, at which a depth of 1,700 fathoms was marked on the chart. This was reached early the next morning, and the line ran out 1,748 fathoms, lat. 36° 31’ 30” N., long. 15° 46’ 30” (No. 60), with a temperature of 13°4C., more than half a degree higher than the temperature of the deepest sounding in the western basin. The tube of the sounding apparatus brought up a sample of yellow clay, so like the bottom at some of the most unpro- ductive spots in the western Mediterranean, that it was not considered advisable to delay the time necessary for even a single cast of the dredge, which at that depth would have occupied nearly a day. Having thus satisfied themselves as far as they could by a few observations that the physical con- ditions of the eastern basin of the Mediterranean were similar to those of the western, they steered for the coast of Sicily. Quietly along the Sicilian coast CHAP. IV. ] THE CRUISES OF THE ‘ PORCUPINE, 195 during the night, in early morning through the narrowest part of the Strait between Messina and Reggio, past Charybdis and the castled rock of Scylla, and so out of the ‘Faro’ into the open sea to the north of Sicily, studded with the Lipari Islands. A temperature sounding taken near Stromboli, lat. 38° 26’ 30" N., long. 15° 32’ E., gave a depth of 730 fathoms, and a bottom temperature of 13°1 C., while the temperature of the surface was 22"5 C. Under the rugged cone of Stromboli the dredgers took another set of temperatures, with the result com- mon to the whole volcanic neighbourhood of Sicily, of a temperature slightly higher than that of the deep water in the western basin of the Mediterranean, a phenomenon of which it would take long and careful observation to determine the cause; and while doing so they pondered on the cloud of smoke hanging over the peak, so suggestive of the theatre of subterranean change beneath, and admired the industry and enter- prise of those who, rendered contemptuous by the familiarity of ages, carried their vineyards ‘all over the cone, save on two sides, looking north-west and south-east, over one or other of which there is a con- tinual discharge of dust and ashes.” Their course was now laid straight for Cape de Gat, which they passed on the 27th of September, arriving at Gibraltar on the 28th. At Gibraltar, Dr. Carpenter resumed his observations and experi- ments on the currents of the Strait. These obser- vations were continued until the 2nd of October, when it became necessary for Captain Calver to re- turn homewards. The coast of Portugal was repassed in fine weather, the time at their disposal not allow- 0 2 196 THE DEPTHS OF THE SEA. [CHAP. IV. ing any urther use of the dredge in the deep water, and after encountering a fresh breeze in the chops of the Channel, on the evening of October the 8th, the ‘ Porcupine’ anchored at Cowes. LILLE DIMON, CHAP. IV. |} THE CRUISES OF THE ‘ PORCUPINE,’ ISS APPENDIX A. Extracts from the Minutes of Council of the Royal Society, and other Official Documents referring to the Cruise of H.ALS. ‘Porcupine’ during the Summer of 1870 :— March 24, 1870. A Letter was read from Dr. Carpenter, addressed to the President, suggesting that an Exploration of the Deep Sea, such as was carried out during 1868 and 1869 in the regions to the North of the British Islands, should now be extended to the South of Europe and the Mediterranean, and that the Council of the Royal Society should recommend such an undertaking to the favourable consideration of the Admiralty, with a view to obtain the assistance of Her Majesty’s Government as on the previous occasions. Resolved,—That a Committee, consisting of the President and Officers, with the Hydrographer, Mr. Gwyn Jeffreys, Mr. Siemens, Professor Tyndall, and Dr. Carpenter, with power to add to their number, be appointed, to consider the expediency of adopting the proposal of Dr. Carpenter, and the plan to be followed in carrying it out, as well as the instruments and other appliances that would be required, and to report their opinion thereon to the Council ; but with power previously to communicate to the Admiralty a draft of such report as they may agree upon, if it shall appear to them expedient to do so in order to save time. April 8, 1870. Read the following Report :— “The Committee appointed on the 24th of March to consider a proposal for a further Exploration of the Deep Sea during the 198 THE DEPTHS OF THE SEA. [CHAP. IV. ensuing summer, as well as the scientific preparations which would be required for a new expedition, beg leave to report as follows :— “The general course proposed to be followed, and the chief objects expected to be attained in a new expedition, are pointed out in the following extract from the letter of Dr. Carpenter, read to the Council on the 24th ult., which was referred to the Committee :— ««The plan which has been marked out between my colleagues in last year's work and myself is as follows :— “Having reason to hope that the “ Porcupine” may be spared towards the end of June, we propose that she should start early in July, and proceed in-a 8.W. direction towards the furthest point to which our survey was carried last year; carefully exploring the bottom in depths of 400 to 800 fathoms, on which, as experience has shown us, the most interesting collec- tions are to be made; but also obtaining a few casts of the Dredge with Temperature-soundings at greater depths, as oppor- tunities may occur. “ 9 |- 2228 36 200n i) 6 47 alas 386 | Li<-7 |. 22-6 36 15 6 52 ae Age | Ors. 8) 27 35 56 26 Go| Or) 2S i 35am ve ee B35) |. 554 | 10 0 29° A. 35 32 6 54 34 ANAC AOe IL Te DHE se 35 AA TG. 53 35 S351 OO) | 23.29 3139) ||, 96138 36 19Se\ 19> | 23-48 55 Soa | 6 26 See OO lite 8. Se 2270 35 50 | 6 0 Sep 503.1 11:8 295-1() 3558 | 52 So say |) Lous 21 0 35 59 D2 AO 586 | 13°4 23-6 36 0 A 40 Al Toa) 13 74 23-6 Bai Ai? 42 7900 ds? 23°°2 35 45 3 57 43 162 | 13:4 23-8 35 24 3 54 44. 455 | 13°0 PALEY) 35 42 3 0 A5 207 | 124 22+6 35 36 2 29 AG AGS ely alan. 0) 23-0, |) 35°39 1 56 47 g45, |) 12-6 210 37 25 1 10 m8, | 1328 | 12-8 23-0 37 10 0 31 eo | dA 12° 7 22-0 36 29 Oust 0) Awecul = — 36 14 Onl 7.B. BOG 152 | = — | 3618 0 24 e145) | 2 7 94-0 36 55 I 10 52 | 660 a= = 36 38 1 38 52a | 590) — ~- 36 36 138 53 HE PS Oe le be 36 53 5 55 hae 1508 | 130 | 24-4 a7 24 6 27 Bae 1456 | 128 24S = te 37 29 6 31 56 390 | 13°6 Poe 6. a |) Sie 8 1 3% 57 DOA = — toon 6 13 10 58 266 | 13°6 DL il al es ae 13 36 59 | 445 | 13°6 24°6 | 36 32 14-12 BOs) 13-4 22 ee 36 ol 15 46 | 204 THE DEPTHS OF THE SEA. (CHAP. IV. PSEA Eiaue | denpeorue, | tomtoneie Position | Gil) e392, | sige AC. | 22 5 C. 38°26’ N.| 15°32’ E Comal as0 ola 0! i 22-45 38 38 15°21 G8 21814 12°4 || 20°2°..| 936 1) ee | 64) 460) 12-4 | 18-8 | 3558 |) bee oom e198.) 12rd! | Lease eae 5 on 66 | 147 — fe 85 56 | a Gian) 188 128) 529799) RS a) atom CHAPTER. V. DEEP-SEA SOUNDING. The ordinary Sounding-lead for moderate Depths.—Liable to Error when employed in Deep Water.—Early Deep Soundings un- reliable-—Improved Methods of Sounding.—The Cup-lead.— Brooke’s Sounding Instrument.—-The ‘ Bull-dog’; Fitzgerald’s ; the ‘Hydra.’—Sounding from the ‘ Poreupine.—The Contour of the Bed of the North Atlantic. In all deep-sea investigations it is of course of the first importance to have a means of determining the depth to the last degree of accuracy, and this is not so easy a matter as might be at first supposed. Depth is almost invariably ascertained by some modification of the process of sounding. Fic 47.—The End of the Dredge-frame. the dredge-frame is 4 ft. 6 in., and it is 6 inches wide at the throat or narrowest part. The dredge used in the deepest haul was somewhat different. About half of each arm next the eye to which the rope was attached, was of heavy chain. I doubt greatly, how- ever, if this is an advantage. The chain drags along in front of the dredge, and may possibly obstruct the entrance of objects and injure them more than a pair of rigid arms would do. On one side the chain was attached to the arm of the dredge by a stop of five turns of spun-yarn, so that in case of the dredge CHAP. VI. ] DEEP-SEA DREDGING. 251 becoming entangled or wedged among rocks or stones, a strain less than sufficient fs break the dredge rope would break the stop, alter the position of the dredge, and probably enable it to free itself ; Qe Lh fee \SCCEECCEEE a CCL CEE fithh i VANE {MI \" i nig | N Fic. 48.—Dredge-frame showing the mode of attachment of the Bag. a Spunyarn Stop. and in case of its taking in a greater load of mud than the rope could bring up, the stop would like- wise give way and allow the dredge to fall into such a position that a large part of its contents would slip 252 THE DEPTHS OF THE SEA. [cHAP. VI. out. The weight of the frame of this dredge, the largest we ever used, was 225 lbs.; it was forged by Messrs. Harland and Wolff of Belfast of the best Lowmoor iron. The dredge-bag was double—the outer of strong twine netting, the inner of bread- . bag. Three sinkers—one of 1 ewt., © the other two of 56 lbs. each—were | attached to the dredge-rope at 500 fathoms from the dredge. The operation of sounding at a depth of 2,485 fathoms in the Bay of Biscay on the 22nd of July, 1869, has already been described in detail. When the depth had been accurately ascertained, about 4.45 p.m. the dredge was let go, the vessel drift- ing slowly before a moderate breeze (force =4:) fromthe N.W. The 3,000 fathoms of rope were all out at 5.50 pM. The diagram (Fig. 50) will | give an idea of the various relative Ht Hi i positions of the dredge and the vessel i | \ Al || according to the plan of dredging \\ ie i adopted by Captain Calver, which ive. 49 The End of the WOFked admirably, and which ap- Dredge frame, showing pears, in fact, to be the only jmede siete which would answer for great depths. A represents the position of the vessel when the dredge is let go, and the dotted line a B the line of descent of the dredge, rendered oblique by the tension of the rope. While the dredge is going down the vessel drifts gradually to leeward; and when the whole (say) 3,000 fathoms of rope are out, C, w, CHAP. VI.] DEEP-SEA DREDGING. 25% and Dp might represent respectively the relative = as : Ae ; Wind i V7 y, => => Ki NY eC iae, HG F CE iN SSS SsSSS]SSSSS2523SSSSSSSEEEzSSSSSSEEEEHB_ SSSSSSsSSSaSSaaa_a m An i HHH TIT ITVIUTITUVTUTTUTUTIITTUITVTITUIU EB RUA RAR WY Yyyyi;;;Kz~—O™~E___—_ YY Yj ty YJ Yy MM Zi 7, Fic. 50.—Diagram of the relative position of the Vessel, the Weights, and the Dredge, in : : dredging in deep water. positions of the vessel, the weight attached 500 254 THE DEPTHS OF THE SEA. [CHAP. VI. fathoms from the dredge, and the dredge itself. The vessel now steams slowly to windward, occupying successively the positions £, F, G, and H. The weight, to which the water offers but little resistance, sinks from w to w’, and the dredge and bag more slowly from D to B. The vessel is now allowed to drift back before the wind from H towards c. The tension of the motion of the vessel, instead of acting immediately on the dredge, now drags forward the weight w’, so that the dredging is carried on from the weight and not directly from the vessel. The dredge is thus quietly pulled along with its lip scraping the bottom in the attitude which it assumes from the centre of weight of its iron frame and arms. If, on the other hand, the weights were hung close to the dredge, and the dredge were dragged directly from the vessel, owing to the great weight and spring of the rope the arms would be continually lifted up and the lip of the dredge prevented from scraping. In very deep dredging this operation of steaming up to windward until the dredge-rope is nearly perpendicular, after drifting for half an hour or so to leeward, is usually repeated three or four times. At 8.50 p.m. we began to haul in, and the ‘ Aunt Sallies’ to fill again. The donkey-engine delivered the rope at the rate of rather more than a foot per second, without a single check. A few minutes before 1 a.m. the weights appeared, and a little after one in the morning, eight hours after it was cast over, the dredge was safely hauled on deck, having in the interval accomplished a journey of upwards of eight statute miles. The dredge contained 13 ewt. CHAP, VI.] DEEP-SEA DREDGING. 290 of very characteristic pale grey Atlantic ooze. The total weight brought up by the engine was— 2,000 fathoms, 24-inch rope . .. . . . 4,000 lbs. WOOO tathoms, Zanch;rope. ..°. = « = « L,d00 RR, 5,500 Ibs. Weight of rope reduced to one-fourth im water = 1,375 Ibs. Dredge and bag a i ea cee Veoh au PAD ey Wozembrouchtupe to G25 ee 7 ee es 1685, Wwieichtrattached, ©) 92 "sistant Se et me pos 224 4, 2,042 lbs. Much more experience will yet be necessary before we can assure ourselves that we have devised the dredge of the best form and weight for work in the deep sea. I rather think that the dredges, 150 to 225 lbs., which we have been in the habit of using, are too heavy. In many instances we have had evidence that the dredge, instead of falling gently upon the surface and then gliding along and gather- ing the loose things in its path, has fallen upon its mouth and dug into the tenacious mud, thereby clogging itself, so as to admit but little more. I mean to try the experiment of heavier weights and lighter dredge-frames in the ‘Challenger,’ and I believe it will be an improvement. In many of our dredgings at all depths we found that, while few objects of interest were brought up within the dredge, many echinoderms, corals, and sponges came to the surface sticking to the outside of the dredge-bag, and even to the first few fathoms of the dredge-rope. This suggested many expedients, and finally » 256 THE DEPTHS OF THE SEA. [CHAP. VI. Captain Calver sent down half-a-dozen of the ‘ swabs’ used for washing the decks attached to the dredge. The result was marvellous. The tangled hemp brought up everything rough and moveable which came in its way, and swept the bottom as it might have swept the deck. Captain Calver’s invention initiated a new era _in deep-sea dredging. After Various experiments we came to the conclusion that the best plan was to attach a long iron transverse bar to the bottom of the dredge-bag, and to fasten large bunches of teazed-out hemp to the free ends of the bar (Fig. 51). We now regard the ‘ hempen tangles ’ as an essential adjunct to the dredge nearly as important as the dredge itself, and usually much more conspicuous in its results. Sometimes, when the ground is too rough for ordinary dredging, we use the tangles alone. There is some danger, how- ever, in their use. The dredgé employed under the most favourable circumstances may be supposed or hoped to pass over the surface of the floor of the sea for a certain distance, picking up the objects in its path which are perfectly free, and small enough to enter the dredge mouth. If they chance to be attached in any way, the dredge rides over them. If they exceed in the least the width of the dredge- opening, at the particular angle at which the dredge may present itself at the moment, they are shoved aside and lost. The Mollusca have by far the best chance of being fully represented in investigations carried on by the dredge alone. Their shells are comparatively small solid bodies mixed with the stones on the bottom, and they enter the dredge along with these. Echino- CHAP, VI. | DEEP-SEA DREDGING. 957 derms, corals, and sponges, on the contrary, are bulky objects, and are frequently partialiy buried in Fie, 51.—Dredge with ‘hempen tangles.’ the mud or more or less firmly attached, so that the dredge generally misses them. With the tangles it S 258 THE DEPTHS OF THE SEA. [CHAP. VI. is the reverse. The smooth heavy shells are rarely brought up, while frequently the tangles loaded with the spiny spheres of OCidaris, great white-bearded Holtenie, elistening coils of Hyalonema, relieved by the crimson stars of Astropecten and Brisinga, pre- sent as remarkable an appearance as can well be imagined. On one occasion, to which I have already referred, I am sure not fewer than 20,000 examples of Lchinus norvegicus came up on the tangles at one haul. They were warped through and through the hempen fibres, and actually filled the tangles so that we could not get them out, and they hung for days round the bulwarks like nets of pickling onions in a greengrocer’s shop. The use of the tangles, which seem so singularly well adapted to their capture, gives therefore a totally unfair advan- tage to the radiate groups and the sponges, and this must always be taken into account in estimating their proportion in the fauna of a particular area. The tangles certainly make a sad mess of the specimens; and the first feeling is one of woe, as we undertake the almost hopeless task of clipping out with a pair of short nail-scissors the mangled remains of sea-pens, the legs of rare crabs, and the dismem- bered disks and separated arms of delicate crinoids and ophiurids. We must console ourselves with the comparatively few things which come up entire, sticking to the outer fibres; and with the reflection that had we not used this somewhat ruthless means of capture, the mutilated specimens would have re- mained unknown to us at the bottom of the sea. The dredge comes up variously freighted according to the locality. Usually, if dexterously managed, CHAP. VI. | DEEP-SEA DREDGING. 259 the bag is about half full. If, from a great depth, beyond the reach of currents, where there is only so slow a movement of the mass of water that the finest sediment is not carried away, it contains usually fine caleareous or aluminous mud alone, with the animals forming the fauna of the locality distributed through it. In shallower water we may have sand or gravel, or stones of various sizes mixed with mud and sand. The next step is to examine the contents of the dredge carefully, and to store the objects of search for future use. The dredge is hauled on deck, and there are two ways of emptyingit. We may either turn it up and pour out its contents by the mouth. or we may have a contrivance by which the bottom of the bag may be made to unlace. The first plan is the simplest and the one most usually adopted. The second has the advantage of letting the mass out more smoothly and easily, but the lacing introduces rather a damaging complication, as it is apt to loosen or give way. Ina regularly organized dredg- ing expedition, a frame is often arranged with a ledge round it to receive the contents of the dredge, but it does very well to capsize it on an old piece of tarpauling. Any objects visible on the surface of the heap are now carefully removed and placed for identification in jars or tubs of sea-water, of which there should be a number standing ready. The heap should not be much disturbed, for the delicate objects contained in it have already been unavoid- ably subjected to a good deal of rough usage, and the less friction among the stones the better. Close to the place where the dredge is emptied s 2 260 THE DEPTHS OF THE SEA. [CHAP. VI. there ought to be one or two tubs about two feet in diameter and twenty inches deep, and each tub should be provided with a set of sieves so. arranged that the lowest sieve fits freely within the bottom of the tub, and the three succeeding sieves fit freely within one another (Fig. 52). Hach sieve is pro- vided with a pair of iron handles through which the hand can pass easily, and the handles of the largest sieve are made long, so that the whole nest ean be lifted without stooping and putting the arms b | | Hille A j big Um Vi U l ii }|| | II I SC — Ty ii me ine TAT TTA HI! mE TH | Tey || TTT sd ee ||) : i ml | | mA Fic. 52.—Set of Dredging Sieves. into the water. The upper smallest sieve is usually deeper than the others ; it is made of a strong open net of brass wire, the meshes a half inch to a side. The second sieve is a good deal finer, the meshes a quarter inch to a side. The third is finer still, and the fourth so close as only to allow the passage of mud or fine sand. The sieves are put into the tub, and the tub filled up to the middle of the top sieve with sea-water. The top sieve is then half filled with the contents of the dredge, and the set of sieves are gently moved up and down in the CHAP. VI. ] DEEP-SEA DREDGING. 261 water. It is of great importance not to give any rotatory motion to the sieves in this part of the process, for such is very ruinous to fragile organisms. The sieves should be gently churned up and down, whether singly or together. The result, of course, is that the rougher stones and gravel and the larger organisms are washed and retained in the upper sieve. The fine mud or sand passes through the _whole of the sieves and subsides into the bottom of the tub, while the three remaining sieves contain, in graduated series, the objects of intermediate size. The sieves are examined carefully in succession, and the organisms which they contain gently removed with a pair of brass or bone forceps into the jars of sea-water, or placed at once in bottles of weak spirit of wine. The scientific value of a dredging operation de- pends mainly upon two things,—the care with which the objects procured are preserved and labelled for future identification and reference, and the accuracy with which all the circumstances of the dredging, position, depth, nature of ground, bottom tempera- ture, date, &c., are recorded. With regard to the preservation of the animals, I cannot here go into detail. There are many ways of preserving, special to the different invertebrate groups; and ‘ taxi- dermy ’ is in itself a complicated art. I will merely mention one or two general points. A specimen in almost every group is of infinitely greater scientific value if it be preserved entire with its soft parts. For this purpose the most usual plan is to place it at once in spirit of wine diluted to about proof. Care must be taken not to put too many specimens 262 THE DEPTHS OF THE SEA. [CHAP. V1. together in one jar, or they will very shortly become discoloured; and the jars ought to be looked to care- fully and the spirit tested, and if necessary renewed after they have been set aside for a day or two, as sea-animals contain a large quantity of water. In hot weather, and if the specimens be bulky, it is often better to use strong spirit. The ordinary methylated spirit of commerce answers sufficiently well for ordinary purposes, though if a specimen be reserved for minute dissection, I prefer using pure, or even absolute alcohol. For very delicate transparent objects,--such as salpee, siphonophora, polycystina, &c.,— Goadby’s solution seems to be preferable: but do what we may, a preserved specimen of one of these lovely objects is a mere caput mortuum, a melancholy sug- gestion of its former beauty; good only for the demonstration of anatomical structure. In preserving marine animals dry, as much of the soft parts should be removed as possible, and replaced by tow or cotton, and the object to be dried should be steeped in several changes of fresh water to get rid of the whole of the salt, and then dried very thoroughly and not too quickly. Every specimen, whether dry or in spirit, should be labelled at once, with the number under which this particular dredging is entered in the dredger’s note-book. It is wonderful how soon things get into confusion if this be not rigorously attended to. The small paper tickets with a fancy margin and gummed on the back, which haberdashers use for ticketing their goods, are to be had of all wholesale stationers at nominal prices, and they are very con- CHAP. VI. } DEEP-SEA DREDGING. 263 venient. Their great disadvantage is that if the bottles on which they are fixed get wet they are apt to come off. Pencils are sold by seed-merchants for writing on tallies which are to be exposed to rain. Perhaps the safest plan is to mark the number and date with such a pencil on a shred of parchment or parch- ment paper, and put it inéo the bottle. This may seem a trifling detail, but so great inconvenience constantly arises from carelessness in this matter, that I feel sure of the sympathy of all who are interested in the scientific aspect of dredging when I insist upon the value of accurate labelling. It is of even greater importance that certain circumstances relating to every individual haul of the dredge should be systematically noted, either in the dredger’s diary, or on a special form prepared for the purpose. ‘The precise position of the station ought to be defined in shore dredging by giving the distance from shore and the bearings of some fixed objects; in ocean dredging by noting accurately the latitude and longitude. In the ‘ Lightning,’ in 1868, we dredged at a station about 100 miles to the north of the Butt of the Lews, and came upon a singular assemblage of interesting animal forms. Next year, in the ‘ Porcupine,’ we were anxious to try again the same spot to procure some additional specimens of a sponge which we were studying. The position had been accurately given in the log of the ‘ Lightning,’ and the first haul at a depth of upwards of half a mile gave us the very same group of forms which we had taken the year before. On our return Captain Calver again dropped the dredge 264 THE DEPTHS OF THE SEA. [cHap. vr. upon the same spot, with like success. The depth in fathoms should be carefully noted, as a most im- portant element in determining the conditions of life and distribution of species; and the nature of the bottom—whether mud, sand, or gravel; and if the latter, it is well to state the nature and composition of the pebbles, and if possible the source from which they may probably have been derived. Now that we have in the Miller-Casella thermometer a_reliable instrument for this purpose, the bottom temperature ought always to be noted. ‘This is important, whether in shallow or in deep water. In shallow water it gives a datum for determining the range of annual variation of temperature which can be endured by certain species; and at great depths it is even more important, as we are now aware that, owing to the movement of masses of water at different tempera- tures in various directions, totally different condi- tions of climate may exist in deep water within a few miles of one another, and the limits of these conditions can only be determined by direct experi- ment. It is important when determining the bottom temperature to note also the temperature of the surface of the sea, the temperature of the air, the direction and force of the wind, and the general atmospheric conditions. If the dredger be purely a zoologist, having no particular interest in special physical problems, it will still be well worth his . while to make all the observations indicated and to publish the results. These then pass into the hands of physical geographers, to whom all trust- worthy additions to the myriad of data which are required to arrive at a true generalization of the CHAP. VI. ] DEEP-SEA DREDGING. 265 phenomena of the distribution of temperature are most acceptable. ‘At the Birmingham Meeting of the British Asso- ciation in 1839 an important committee was ap- pointed “for researches with the dredge, with a view to the investigation of the marine zoology of Great Britain, the illustration of the geographical distribution of marine animals, and the more accurate determination of the fossils of the plio- cene period: under the superintendence of Mr. Gray, Mr. Forbes, Mr. Goodsir, Mr. Patterson, Mr. Thompson of Belfast, Mr. Ball of Dublin, Dr. George Johnston, Mr. Smith of Jordan Hill, and Mr. A. Strickland.”? The appointment of this committee may be regarded as the initiation of the systematic employment _of this method of research. Edward Forbes was the ruling spirit, and under the genial influence of his contagious enthusiasm great pro- eress was made during the next decade in the know- ledge of the fauna of the British seas, and many wonderfully pleasant days were spent by the original committee and by many others who, from year to year, were ‘added to their number.’ Every annual report of the British Association contained commu- nications from the English, the Scottish, or the Irish branches of the committee, and in 1850 Edward Forbes submitted its first general report on British marine zoology. ‘This report, as might have been anticipated from the eminent qualifications of the reporter, was of the highest value; and taken along with his remarkable memoirs previously published, “on the distribution of the Mollusca and Radiata of the Aigean Sea,”’ and “ on the geological relations "266 THE DEPTHS OF THE SEA. [CHAP. VI. of the existing Fauna and Flora of the British Isles,’’ may be said to mark an era in the progress of human thought. After enumerating various additions to our know- ledge of the distribution of marine invertebrata within the British area which were still to be de- sired, Forbes concludes his report with the following sentence: “And lastly, though I fear the consum- mation, however devoutly wished for, is not likely soon to be effected, a series of dredgings between the Zetland and the Feeroe Isles, where the greatest depth is under 700 fathoms, would throw more light on the natural history of the North Atlantic and on marine zoology generally than any investigation that has yet been undertaken.” | To Forbes’s general report succeeded many reports from the different sections into which from year to year the committee divided itself. Among these I may mention particularly the very excellent work done by the Belfast dredging committee, communi- cated to several meetings of the Association by the late Mr. George C. Hyndman; the reports of the Dublin committee by the late Professor Kinahan and Professor E. Perceval Wright; the important lists of the fauna of the East Coast of England re- ported on behalf of the Natural History Society of Northumberland, Durham, and Newcastle-upon-Tyne, and of the Tyne-side Naturalists’ Field Club, by Mr. Henry T. Mennell and Mr. G. 8. Brady; and lastly, the invaluable reports on the marine fauna of the Hebrides and Shetland, compiled at an extraordinary expense of labour, discomfort, and privation—doubt- less with an immediate guerdon of infinite enjoyment CHAP, VI.] DEEP-SEA DREDGING. 267 —through many years, by Mr. Gwyn Jeffreys, Mr. Barlee, the Rev. A. Merle Norman, and Mr. Edward Waller, and communicated to the Transactions of the Association from 1863 to 1868. The dredging com- mittees of the British Association, combining the pursuit of knowledge with the recreation of their summer holidays, may be said to have worked out the fauna of the British area down to the 100-fathom line, for the dredger is now rarely rewarded by a conspicuous novelty, and must be contented that the greater number of his additions to the British lst are confined to the more obscure groups. . Meanwhile some members of the dredging com- mittee and their friends who had time and means at their disposal pushed their operations farther a-field, and did good service on foreign shores. In 1850, Mr. MacAndrew published many valuable notes on the lusitanian and mediterranean faunz; and in 1856, at the request of the biological section of the British Association, he submitted to the Chel- tenham meeting a general “report on the marine testaceous mollusca of the North-east Atlantic and neighbouring seas, and the physical conditions affect- ing their development.” ‘The field of these arduous labours extended from the Canary Islands to the North Cape, over about 43 degrees of latitude, and many species are recorded by him as having been dredged at depths between 160 and 200 fathoms off the coast of Norway. Subsequently, Mr. Gwyn Jeffreys went over some of the same ground, and made many additions to the lists of his predecessors. Nor were our neighbours idle. In Scandinavia a brilliant triumvirate—Lovén of Stockholm, Steen- 268 THE DEPTHS OF THE SEA, ~ [CHAP. VI. strup of Copenhagen, and Michael Sars of Chris- tiania—were making perpetual advances in the knowledge of marine zoology. Milne-Edwards was illustrating the fauna of the coast of France, and Philippi, Grube, Oscar Schmidt, and others were continuing in the Mediterranean and the Adriatic the work so well begun by Donati, Olivi, Risso, Delle Chiage, Poli, and Cantraine ; while Deshayes and Lacaze Duthiers illustrated the fauna of the coast of Algeria. So much progress had already been made at home and abroad, that in the year 1854 Edward Forbes considered that the time had arrived for giving to the public, at all events a pre- liminary sketch of the fauna of the European seas —a work which he commenced, but did not live to finish. I need scarcely say that these operations of the British Association dredging committees were carried on generally under the idea that at the 100-fathom ‘line, by which amateur work was practically limited, they approached the zero of animal life—a notion which was destined to be gradually undermined and finally completely overthrown. From time to time, however, there were not wanting men of great skill and experience to maintain, with Sir James Clark Ross, that “from however great a depth we may be enabled to bring up the mud and stones of the bed of the ocean, we shall find them teeming with animat life.’ From the very general prevalence of the negative view there was little to stimulate to the investigation of the bottom at great depths, and data gathered very slowly. I have already referred (p. 18 e¢ infra) to the CHAP. VI.] DEEP-SEA DREDGING. 269 observations of Sir John Ross in 1818, of Sir James Ross in 1840, and of Mr. Harry Goodsir in 1845. In the year 1844 Professor Lovén con- tributed a paper, “on the bathymetrical distribu- tion of submarine life on the northern shores of Scandinavia,’ to the British Association. He says, “With us the region of deep-sea corals is character- ized in the south by Oculina ramea and Terebratula, and in the north by Astrophyton, Cidaris, Spatangus purpureus of an immense size, all living; besides Gor- gome and the gigantic Alcyonium arboreum, which continues as far down as any fisherman’s line can be sunk. As to the point where animal life ceases, it must be somewhere, but with us it is unknown.’’! In 1863 the same naturalist, referring to the result of the Swedish Spitzbergen expedition of 1861, when mollusca, crustacea, and hydrozoa were brought up from a depth of 1,400 fathoms, expresses the remarkable opinion, which later investigations appear generally to support, that at great depths, wherever the bottom is suitable, “a fauna of the same general character_extends from pole to pole through all degrees of latitude, some of the species of the fauna being very widely distributed.” ° In 1846 Keferstein mentions having seen in Stock- holm a whole collection of invertebrate animals— crustacea, phascolosoma, annelids, spatangus, myrio- trochus, sponges, bryozoa, rhizopoda, &c.—taken at a depth of 1,400 fathoms during O. Torell’s Spitz- ? Report of the Fourteenth Meeting of the British Association, held at York in September 1844. (Transactions of the Sections, p. 50.) 2 Forh. ved de Skand. Naturforskeres Mode i Stockholm, 1863, p. 384, 270 THE DEPTHS OF THE SEA. [cHap. VI. bergen expedition in the ‘Maclean nets,’ and in the same year O. Torell alludes to one of the crus- taceans from that depth being of a bright colour.t In 1846 Captain Spratt, R.N., dredged at a depth of 310 fathoms forty miles east of Malta a number of mollusea which have been subsequently examined by Mr. Gwyn Jeffreys and found to be identical with species dredged at considerable depths in the northern seas during the ‘Porcupine’ expedition. The list includes Leda pellucida, Puttipp1; Leda acuminata, JEFFREYS; Dentalium agile, SARS; JTela tenella, JEFFREYS; Hulima stenostoma, JEFFREYS; Trophon barvicensis, JOHNSTON; Pleurotoma cari- natum, Bivona; and Philine quadrata, 8. V. Woop. Captain Spratt observes that he ‘believed animal life to exist much lower, although the general character of the Algean is to lmit it to 300 fathoms.” ’ In 1850 Michael Sars, in an account of a zoolo- gical excursion in Finland and Loffoten, expressed his conviction that there is a full development of animal life at considerable depths off the Norwegian coast. He enumerated nineteen species taken by himself at depths beyond 3800 fathoms, and pointed out that two of these were the largest species known of their respective genera.’ 1 Nachrichten der Konigl. Gesellsch. der Wissensch. zu Gottingen. Marz 1846. * On the Influence of Temperature upon the Distribution of the Fauna in the Aigean Sea. Report of the Eighteenth Meeting of the British Association, 1848. 3 Beretning om en 1 Sommeren, 1849, foretagen zoologisk Reise i Lofoten og Finmarken. Christiania, 1850. CHAP. V1. ] DEEP-SEA DREDGING. OFA I have referred likewise (p. 26) to Professor Fleeming Jenkin’s notes on the living animals attached to the Mediterranean cable at a depth of 1,200 fathoms, and to the results of Dr. Wallich’s special investigations on board H.M.S. ‘ Bull-dog.’ In a general review of the progress of knowledge as to the conditions of life at great depths, these investi- gations deserve special notice, as, even if they must still be regarded as somewhat unsatisfactory, they distinctly mark a stage in advance. Although, from the imperfection of the means at his disposal, Dr. Wallich could not bring home evidence sufficient absolutely to satisfy others, he was convinced in his own mind from what he saw, that living beings high in the scale of organization might exist at any depth in the ocean; he expounded clearly and forcibly - the train of reasoning which led him to this belief, and subsequent events have amply justified his con- clusion. The space at my disposal will not allow me to quote and discuss Dr. Wallich’s arguments, in some of which I thoroughly concur, while from others I am compelled to dissent. The facts were most important, and their significance increases now that they are fully confirmed and illustrated by ope- rations on a large scale. In lat. 59° 27’ N., long. 26° 41' W., a depth of 1,260 fathoms having been previously ascertained, ‘‘ a new kind of deep-sea dredge was lowered; but in consequence of its partial failure, a second apparatus (namely, the conical cup) was em- ployed, fifty fathoms of line in excess of the recorded depth being paid out in order to ensure the unchecked descent and impact of the instrument at the bottom. The dredge had already brought up a small quantity 272 THE DEPTHS OF THE SEA. [cHAP. VI. of unusually fine globigerina deposit and some small stones. The second instrument came up quite full of the deposit ; but it was neither so free from amorphous matter, nor did it contain any of the small stones. Adhering, however, to the last fifty fathoms of line, which had rested on the ground for several moments, were thirteen ophiocome, varying in diameter across the arms from two to five inches.” The misfortune of these star-fishes was that they did not go into the dredge ; had they done so, they would at once have achieved immortality. Now, of course, we have no doubt that they came from the bottom, but their irregular mode of appearance left, in the condition of knowledge and prejudice at the time, a loophole for scepticism. In three soundings, including that in which the star-fishes were obtained, at 1,260, 1,918, and 1,268 fathoms respectively, ‘“‘minute cylindrical tubes oc- curred, varying from one-eighth to half an inch in length, and from one-fiftieth to one-twentieth of an inch in diameter. These were built up almost ex- clusively of very small globigerina shells, and still more minute calcareous débris cemented together.” . “The shells forming the outer layer of the tubes were colourless, and freed of all sarcodic matter; but the internal surface of the tubular cylinder was lined with a delicate yet distinct layer of reddish chitine.”’ Dr. Wallich is satisfied that these tubes contained some species of annelid. “In a sounding taken in lat. 63° 31’ N., long. 13° 45° W., in 682 fathoms, a portion of a serpula-tube five- twelfths of an inch in length, and about three- sixteenths of an inch in diameter, belonging to a CHAP. VI.] DEEP-SEA DREDGING. 273 known species, came up in such a condition as to leave no room for doubt that it had been broken off the rock or stone to which it was adherent by the sounding-machine, and that the animal was living; whilst a smaller Serpwla and a cluster of apparently living polyzoa were adherent to its ex- ternal surface. A minute Spirordis also occurred in this sounding. Lastly, from a depth of 445 fathoms, within a short distance of the south coast of Iceland, a couple of living amphipod crustaceans were ob- tained, and a filamentous annelid about three-quarters of an inch in length.” Basing his opinion principally upon these facts, Dr. Wallich, in conclusion, submits several propositions, the two most important of which may be said to anticipate the more remarkable results of our subsequent work. As the others are merely founded upon what I conceive to be a mistaken determination of the animal species captured, I need not now quote them.’ “J. The conditions prevailing at great depths, although differing materially from those which pre- vail at the surface of the ocean, are not incompatible with the maintenance of animal life. * * * * * * * «5. The discovery of even a single species, living normally at great depths, warrants the inference that the deep sea has its own special fauna, and that it has always had it in ages past; and hence that many fossiliferous strata heretofore regarded as having been 1 And see Professor Sars’ ‘Bemerkninger over det dyriske Livs Udbredning i Havets Dybder, med serligt Hensyn til et af. Dr. Wallich i London mylig udkommet Skrift, “The North Atlantic Sea- bed.”’ (Vidensk.-Selsk. Forhandlinger for 1864.) ik 274 THE DEPTHS OF THE SEA. (CHAP. VI. deposited in comparatively shallow water, have been deposited at great depths.’’’ 3 In 1864, Professor Sars made a great addition to his list of species from depths of from 200 to 300 fathoms off the coast of Norway. He remarks :— «The species of animals named are not certainly very numerous (92), yet when we consider that most of them were taken accidentally, attached to the lines of the fishermen, and that only in a few instances the dredge was used at these great depths, it will be seen that there is a very interesting field here for the Naturalist furnished with the proper instruments.” In 1868 Professor Sars made a still further addi- tion to the deep-sea fauna of the Norwegian Seas ; an addition so important, that he remarks ‘that it is so great as to give a tolerably complete idea of the general fauna of these coasts.” This increase of knowledge, Professor Sars states, is almost entirely due to the indefatigable labours of his son, G. O. Sars, an Inspector of Fisheries under the Swedish Government, who took advantage of the opportuni- ties given by his occupation to dredge down to 450 fathoms on some parts of the coast, and among the Loffoten Islands. Sars likewise acknowledges many contributions from his old fellow-labourers, Danielssen and Koren. The number of species from depths be- tween 250 and 450 fathoms on the coast of Norway now reaches 4.27, thus distributed :— Species. 4 ( Rhizopoda |”) = 2 ee EROLOZOM Cyr Ae = 7- l Poriferdy ". ; 2 — 73 ‘ North Atlantic Sea-bed, p. 154. CHAP, VI.] DEEP-SEA DREDGING. O75 Species. Hydrozoa . 2 Ccelenterata. | athotoalt 9 — 22 Crmoid ear mage pes), <1. es, et) ae Eéhinodermata . | Asteridea, including Ophiuridea. 21 Echinoidea Hy meg 5 | Holothuridea . 8 — 36 ( Gephyrea . 6 MesINES Annelida 51 — 57 | Polyzoa. 35 Tunicata : ae eh Mollusca, «.... ..-- Semachiopoda, .- 2 we 4 | Momenitera’, - 5 Diplodonta rotundata . . . aa 1 valve. Modiolabarbata . . .°. -. 1 Nucula nucleus . . . . .| Several. Leda emarginata . . .. . 3 PEeMSUDIAUQI EM Ecaics. genet ee 4 Arca tetracona jz =... = 8 antiquata es ae S52 1 valve. Pectunculus elycimeris eGo Bas 1 and valves. Lima subauriculata . 2. . | Sc Valves. Pecten jacobeus . . . . + ak Valves. oo a UD DUSmcey a hat here te Valves. 5) polymorphs ::o2 |.) 1 oa Valves. oy WEED. oho mp oo oh 1 i> MSUTIS See ae nc) ees oe Valves. SUICAPUSH) Weic. core =. a 1 and valves. Anomia patelliformis . . . Pileopsis hungaricus . . . a 1 Bulla lionaria oa es es 1 Sy mMCLATIC MAR ee ke shen eral ee 2 Bee MNVGaIbIS) ceo asiecieme? Mrs a + oy Striatila 3 we eqs 1 Rissoa bruguieri . < oes a | 3 » _ carinata (costata) A eet Se 2 Longer, destitute acuta, Var... >. =a aoe 5 of ribs, one ‘i very large. > ) desmarestin “2 0. ae 3 ! A ae cimex, but 2 BB oN g Scu ce Re minute. Natica macilenta. . . . . 2 Huolimapolitac., . 0. 9s... be 1 35g SGUSLOTLA es, es te a ae 1 Chemnitzia varicosa. . . . as | 4 Imperfect. > elegantissima . . ee 4 55 indistincta (?). . ake 2 - i ae eee 3 Kulimella acicula. . . . . 1 Trochus tenuis, or dubius . . sae 1 9» Wasuse s . = =. . | .Several: 5 TMOMGASUL ss Lava Siw 8 ee a8 Several. Turritella terebra. . . . . Few. | 6 Small. 3 tricostalis . . . . i Cerithum vulgatum, var... a 1 As reticulatum . . . | Er Several. . - at | ee 2 White. HesuSs;muricatUS -. . 2. ./| 1 l § This species at 2 ‘ eee | Gibraltar. Pleurotoma nanum . .. .| I +3 secalinum : 1 Murex tetrapterus . . . . | oe 2 Chenopus pes-pelecani . . . 1 BUeCINUMI 3 6) te | 1 Mitra ebenea. . 2... . | Se 1 | Bright orange “ = SL Serisoey <7 1 | colour, banded, | small, striated. Ringicula auriculata. . . . Ee | 2 Marginella secalina . . . . | 3 | 4 As clandestina . . ./| Several. Several. Cypreapulem sts s,s Ae | 2 Cimanisshystrix.9/5 GH. | 3 | PASO ste rear tor is . FDOPUYOES) fos ss pe os ‘ CHAPTER, VIL DEEP-SEA TEMPERATURES. Ocean Currents and their general Effects on Climate.— Determination of Surface Temperatures.—Deep-sea Thermometers.—The ordinary Self-registering Thermometer on Six’s principle-—The Miller- Casella modification.—The Temperature Observations taken during the Three Cruises of H.M.S. ‘ Porcupine’ in the year 1869. AppEnpDIx A,—Surface Temperatures observed on board H.M.S. ‘Porcupine’ during the Summers of 1869 and 1870. Appgenpix B.—Temperature of the Sea at different Depths near the Eastern Margin of the North Atlantic Basin, as ascertained by Serial and by Bottom Soundings. APPENDIX C.—Comparative Rates of Reduction of Temperature with Increase of Depth at Three Stations in different Latitudes, all of them on the Eastern Margin of the Atlantic Basin. AppEeNDIxX D.—Temperature of the Sea at different Depths in the Warm and Cold Areas lying between the North of Scotland, the Shetland Islands, and the Féroe Islands; as ascertained by Serial and Bottom Soundings. Appenpix E.—Intermediate Bottom Temperatures showing the Inter- mixture of Warm and Cold Currents on the Borders of the Warm and Cold Areas. Ir the surface of this world of ours were one uniform shell of dry land, other circumstances of its central heat, its relation in position to the sun, and to its investing atmospheric envelope, remaining the samc, some zones would present certain pecu- CHAP. VIT.] DEEP-SEA TEMPERATURES. 285 liarities in temperature, owing to the mixture of. hot and cold currents of air; but in the main, iso- thermal lines, that is to say, lines drawn through | places having the same mean temperature, would coincide with parallels of latitude. A glance at any isothermal chart, whether for the whole year, for summer, for winter, or for a single month, will show that this is far from being the case. The lines of equal temperature deviate everywhere, and often most widely, from their normal parallelism with the parallels of latitude and with each other. A glance at the same chart will also show, that while there is an attempt, as it were, on the part of the iso- thermal lines to maintain their normal direction through the centre of great continents, the most marked curves, indicating the widest extensions of uniform conditions of temperature, are where there is a wide stretch of open sea extending through many degrees of latitude, and consequently includ- ing very different climatal conditions. The lands bordering upon the ocean partake in this general diffusion of heat and amelioration of climate, and hence we have the difference between continental and insular climates—the former giving extremes of summer heat and winter cold, and the latter a much more uniform temperature, somewhat below the normal temperature within the tropics, and usually greatly above it beyond their limits. The islands of Ireland and Great Britain and the west coast of the Scandinavian peninsula are in- volved in the most extreme system of abnormal curves which we have in any of the ocean basins; and to this peculiarity in the distribution of tem- 286 THE DEPTHS OF THE SEA. [cHAP. VII. perature in the North Atlantic we are indebted for the singular mildness of our winter climate. The chart Pl. VII., the general result reduced from many hundreds of thousands of individual observations, gives the distribution of the lines of equal mean temperature for the surface of the North Atlantic for the month of July; and it will be seen that the isotherms, instead of passing directly across the ocean, form a series of loops widening and flatten- ing northwards, all participating in certain secondary deflections which give them a scalloped appearance, but all of them primarily referred to some common cause of the distribution of heat, having its origin somewhere in the region of the Straits of Florida. These peculiarities in the distribution of tempera- ture on the surface of the sea may usually be very immediately traced to the movement of bodies of water to and from regions where the water is exposed to different climatal conditions ;—to warm or cold ocean currents, Which make themselves manifest like- wise by their transporting power, their effect in speeding or retarding vessels, or diverting them from their courses. Frequently, however, the current, although possibly involving the movement of a vast mass of water, and exerting a powerful influence upon climate, is so slow as to be imperceptible; its steady onward progress being continually masked by local or variable currents, or by the drift of the prevailing winds. The Gulf-stream, the vast ‘warm river’ of the North Atlantic, which produces the most remark- able and valuable deviations of the isothermal lines which we meet with in any part of the world, is in cHaAP. V1. ] DEEP-SEA TEMPERATURES. DONT this way imperceptible by any direct effect upon navigation beyond the 45th parallel of north latitude, a peculiarity which has produced and still produces ereat misconceptions as to its real character. The mode of determining the surface temperature of the ocean is sufficiently simple. A bucket is let down from the deck of the vessel, dashed about for a little in the water to equalize the temperature, and filled from a depth of a foot or so below the sur- face. ‘The temperature of the water in the bucket is then taken by an ordinary thermometer, whose error is known. A common thermometer of the Kew Observatory pattern graduated to Fahrenheit degrees can be read with a little practice to a quarter of a degree, and a good-sized centigrade thermometer to a tenth. Observations of surface-temperature are usually made every two hours, the temperature of the air being taken with each observation, and the latitude and longitude noted at noon, or more fre- quently by dead reckoning if required. Every observation of the surface-temperature of the sea taken accurately and accompanied by an equally exact note of the date, the geographical position, and the temperature of the air, is of value. The surface observations taken from H.M.S. ‘ Por- cupine’ during her dredging cruise, in the summer of 1869, are given in Appendix A. The surface-temperature of the North Atlantic has been the subject of almost an infinite number of such observations, more or less accurate. Dr. Petermann, in a valuable paper on the northern extension of the Gulf-stream, reduces the means of more than a hundred thousand of these, and deduces the scheme 288 THE DEPTHS OF THE SEA. [CHAP. VII. of curves which has been used with some slight modification in the construction of this chart. Until very recently little or nothing has been _ known with any certainty about the temperature of the sea at depths below the surface. This is, however, afield of inquiry of very great importance in Physical Geography, as an accurate determination of the tem- perature at different depths is certainly the_best, frequently the only available means of determining the depth, width, direction, and generally the path of the warm ocean currents, which are the chief agents in the diffusion of equatorial heat; and more espe- cially of those deeper indraughts of frigid water which return to supply their place and to com- plete the general cycle of oceanic circulation. The main cause of this want of accurate knowledge of deep-sea temperatures is undoubtedly the defective- ness of the instruments which have been hitherto employed. The thermometer which has been almost universally used for this purpose is the ordinary self-registering thermometer on Six’s construction, enclosed in a strong copper case, with valves or apertures below and above to allow a free current of water to pass through the case and over the surface of the instrument. Six’s registermg thermometer (Fig. 53) consists of a glass tube bent in the form of a V, one limb terminating in a large cylindrical bulb, entirely filled with a mixture of creosote and water. The bend of the tube contains a column of mercury, and the other limb ends in a small bulb partially filled with creosote and water, but with a large space empty, or rather containing the vapour of the CHAP. VIL.] DEEP-SEA TEMPERATURES. 289 liquid and slightly compressed air. 250)| 0-4.) O° SC.) 1° 0C | 0-7C)) 0-8 C tO 500 | 0:4 fi 7 1°5 1-4 1:7 | 0=65 4 aes) %o. | 99 2-2 2°3 2:5 | s0=0an 1,000 0-8 2:9 2-9 a 9-7. Oe 1,250 | 0-9 S50 ego padres ye Wem feo 1,500 | 0-8 4-3 A> 3 8 Aza 4°3 | 0°38 1,750 | 0-95 | 4-6 4-9 | 497. 9) 527m SG }2000:)1s1) |) 5-4 | 5:5 | 5:38 1) 6-4 ie 2 250 1) len 6-2 6-0 6-0 | 6°8 | Oe8 12,500 | 1-2 Too | 6% 6-5 | 726 | Org The mean difference for each 250 fathoms in each thermometer is as follows :— CHAP. VIT.] HEP-SEA TEMPERATURES. 297 Thermometer. Difference. Standard . = 1 C. 54 , 479 56 . + 0°67 (hae + (0) °65 (Bie j + 0°76 ‘Thomson . + 0-03 During these experiments the water in the cylin- der was of course maintained as far as possible at the same—or at a known temperature; a certain amount of calorific effect must, however, be pro- duced by the sudden compression of the water, and the next series of experiments was performed in order to determine the amount of that effect. Three of Phillips’s encased maximum thermometers (Sir William Thomson’s design), being entirely protected from any effect fron. compression, were employed for this purpose, with the following result :— Pressure, 6,817 lbs. = 2,500 fathoms. Thermometer. | Difference. 5 Se 7 + 0°05 C Orde Se es es +0 92 9,645 . + 0°11 so that this source of error is absolutely trifling. The true error of the Miller-Casella thermometer, as deduced from these observations, is— For 250 fathoms 0°:079 C. For 2,500 fathoms 0°:79 C. 298 THE DEPTHS OF THE SEA. [CHAP. VII. This, therefore, may be regarded as a perfect instru- ment for all ordinary purposes. A number of the instruments which had been previously tested in the press were sent out in the ‘Porcupine’ on her summer cruise in 1869, and on her return the results of Captain Calver’s observa- tions at different depths in the ocean were carefully compared with the effects of equivalent pressures ap- plied to the thermometers in Mr. Casella’s ‘ Bramah’s press.’ The result in the ocean, contrary to that in the hydraulic press, proves that the elasticity is not regular or in a ratio to the pressure, but that after continuing regular up to a pressure of 1,000 fathoms, it decreases in a compound ratio to a pressure of 2,000 fathoms, when its elasticity nearly ceases. The following table gives an abstract of the behaviour of Casella’s ordinary Hydrographic Office thermometers in the ocean and in the press :— | | ERROR. | Per 250 FaTHOMS, Pressure. | | Press. Ocean. | Press. | Ocean. Fathoms. A s: | 5 250 0 7260, | O° 738.0. |) 0° 7266.4) Osa 500 1 + 548 15564 I Or aii | O =4782 | 750 2-123 2°223 | 0° 708 | (0.°745leeaee | 1,000 2° 474 3° 015 | 0° 674 0: 754 | 1,250 Br25o | 9B 492 || 0 6b: 0 - 698 | 1,500 4:107 fe eeg ail | O° 684 0 + 653 1,750 4 +555 4-056 0 + 650 LO ra 7/09) 2,000 De oo 4 4° 284 0 - 669 0: 536 2,250 6: 021 — 0 + 669 a 2.500 6° 817 at 0 =682: | wae For taking bottom temperatures at great depths two or more of the Miller-Casella thermometers are CHAP. VII.] DEEP-SEA TEMPERATURES. 299 lashed to the sounding-line at a little distance from one another, a few feet above the attaching ring of a ‘detaching’ sounding instrument. The lead is run down rapidly, and, after the weight has been disengaged by contact with the ground, an interval of five or ten minutes is allowed to elapse before hauling in. ‘The shorter of these periods seems to be quite sufficient to insure the instrument acquiring the true temperature. In taking serial temperature soundings—that is to say, in determining the tem- perature at certain intervals of depth in deep water ——the thermometers are attached above an ordinary deep-sea lead, the required quantity of line for each observation of the series run out, and the ther- mometers and lead are hove in each time. This is a very tedious process; one serial sounding in the Bay of Biscay, where the depth was 850 fathoms and the temperature was taken at every fifty fathoms, occupied a whole day. I ought to mention that in taking the bottom temperature with the Six’s thermometer the instru- ment simply indicates the lowest temperature to which it has been subjected; so that if the bottom water were warmer than any other stratum through which the thermometer had passed, the observation would be erroneous. This is only to be tested by serial soundings, but in every locality where the temperature was observed during the ‘ Porcupine’ expeditions the temperature gradually sank, some- times very steadily, sometimes irregularly, from the surface to the bottom, the bottom water having been constantly the coldest. It is probable that under certain conditions in the Polar seas, where the sur- 300 THE DEPTHS OF THE SEA. [CHAP. VIL. face is sometimes subjected to intense cold, warmer water may be found below, until the balance is restored by convection. This I believe, however, to be entirely exceptional; and it may certainly be taken as the rule for all latitudes, that if we dis- regard the film which is affected by diurnal altera- tions, the temperature sinks from the surface to the bottom. The first important series of deep-water tempera- ture observations was made during the Arctic voyage under Sir John Ross in the year 1818. On Sept. the Ist, lat. 73° 37’ N., long. 77° 25’ W., the temperature at the surface being 1°3 C., the registering thermo- meter gave at eighty fathoms 0° C., and at 250 fathoms — 1°. 4C. On the 6th of September, lat. 72° 23’ N., long. 73° 07’ W., the first serial sounding on record was taken, the thermometer having been let down to 500, 600, 700, 800, and 1,000 fathoms in succession, the thermometer showing each time a lower temperature and indicating at the greatest depth named a temperature of —38°6C. On the 19th of September, in lat. 66° 50’ N., long. 60° 30’ W., another serial sounding was taken, the tempera- ture being registered at 100 fathoms —0"9 C., at 200 —1°:7 C., at 400 —2°-2 C., and at 660 fathoms — 3°6C.- On the 4th of October, lat. 61° 41’ N., | long. 62° 16° W., Sir John Ross sounded, but found no ground in 950 fathoms; at the same time the self-registering thermometer was sent down, and the temperature of the sea at that depth was found to be 2° C., while at the surface it was 4° C., and the air at 2°"7 C. I am informed by General Sir Edward Sabine, who accompanied Sir John Ross’s expedition, CHAP. VI. | DEEP-SEA TEMPERATURES. 301 that these observations were made with registering thermometers guarded somewhat in the same way as those which we employed in the ‘ Porcupine.’ There is almost sufficient internal evidence that the mode of protecting these thermometers must have been satisfactory, for the temperatures at the greatest depths are such as might have been expected from Miller-Casella thermometers. Unguarded instru- ments would certainly have given higher indica- tions. The last of the observations quoted, a considerable way up Davis’ Strait, is of great interest. The tem- perature of the surface of the sea was nearly a degree and a half Centigrade above that of the air, and the temperature of the water was altogether unusually high. It is now well known that at certain seasons of the year a very marked extension of the Gulf-stream passes into the mouth of the Strait. The isotherms for September and July are shown on the chart from data kindly procured for me by Mr. Keith Johnston. Sir Edward Sabine, in an extract from his pri- vate Journal of Sir John Ross’s voyage quoted by Dr. Carpenter,’ gives a lower temperature than any hitherto recorded. He says: ‘“‘ Having sounded on September 19th, 1818, in 750 fathoms, the regis- tering thermometer was sent down to 680 fathoms, and on coming up the index of greatest cold was at 25°75 Fahrenheit (—3°5 C.), never having known it lower than 28° (— 2°:2 C.) in former instances, even at a depth of 1,000 fathoms; and at other times 1 Dr. Carpenter’s Preliminary Report on Deep-Sea Dredgings. Pro- ceedings of the Royal Society of London, vol. xvii. p. 186. 302 THE DEPTHS OF THE SEA. (CHAP. VII. when close to the bottom, I was very careful in examining the thermometer, but could discover no other reason for it than the actual coldness of the water.” Notwithstanding these observations and several others telling in the same direction,—such as those of Lieutenant Lee of the U.S. Coast Survey, who in August 1847 found a temperature of 2"7 C. below the Gulf-stream, at the depth of 1,000 fathoms, in. lat. 35° 26 N., and long. 73° 12’ W.; andmon Lieutenant Dayman, who found the temperature at 1,000 fathoms, in lat. 51° N. and long. 30° W., to be 0°4 C., the surface temperature being 12°5 C., —the impression seems to have prevailed among physicists and physical geographers that salt water followed the same law as fresh water, attaining its greatest density at a temperature of 4° C. The necessary result of this condition, were it to exist, is thus stated by Sir John Herschel: ‘In very deep water all over the globe a uniform temperature of 39° Fahrenheit (4° C.) is found to prevail; while above the level where that temperature is first reached, the ocean may be considered as divided into three great regions or zones—an equatorial and two polar. In the former of these warmer, and in the latter colder water is found on the surface. The lines of demarkation are of course the two isotherms of 39° mean annual temperature.” Dr. Wallich gives an excellent réswmé of this curious fallacy. He says: “ But whilst the temperature of the atmo- sphere beyond the line of perpetual congelation goes on gradually increasing, that of the water below the isothermal line remains constant to the bottom. CHAP. VII.] DEEP-SEA TEMPERATURES. 303 Were it not for the operation of the law on which the latter phenomenon depends, the entire ocean would long since have become solidified, and both sea and land rendered unfit for the habitation of living organisms. Unlike other bodies which ex- pand and become lighter with every rise in tempera- ture, water attains its maximum density, not under the lowest degree of cold, but at 39°5 Fahrenheit ; and consequently so soon as the superficial layer of sea is cooled down to this degree, it descends, and allows a fresh portion to ascend and be in turn cooled. This process is continued until the whole upper stratum is reduced in temperature to 39°°5, when, instead of contracting further, it begins to expand and get lighter than the water beneath, floats on it, becomes further cooled down, and at 28°65 is. converted into ice...,. = Thus. under the operation of an apparently exceptional law, the equilibrium of the oceanic circulation is maintained ; for whilst at the equator the mean temperature of the surface layer of water, which is 82°, gradually decreases, until at a depth of 1,200 fathoms it be- comes stationary at 39°5, and retains that tempera- ture to the bottom, within the Polar regions and extending to lat. 56° 25’ in either hemisphere, the temperature increases from the surface downwards to the isothermal line, beyond which it remains uniform as in the former case. Hence in lat. 56° 25’ the temperature is uniform the whole way from the surface to the bottom ; and as has been found by observation about lat. 70°, the isothermal line occurs at 750 fathoms below the surface.’’’ 1 Dr. Wallich: North Atlantic Sea-bed, p. 99. 304 THE DEPTHS OF THE SEA. [cHaP. VII. There can be no doubt that this view, which of late years has received almost universal acceptance, is entirely erroneous. It has been shown by M. Despretz,' as the result of a series of carefully con- ducted experiments which have since been frequently repeated and verified, that sea-water, as a saline solution, contracts and increases steadily in density down to its freezing-poiut, which is, when kept perfectly still, about — 3°67 C. (25°4 F.), and when agitated — 2°55 C. The temperature observations of Sir James Clarke Ross during his Antarctic voyage in 1840-41, seemed to give support to the theory of a constant temperature of 4°°5 C. for deep water, but these obser- vations have as evidently been made with unguarded instruments, as those of Sir John Ross in 1818 with instruments defended from pressure; and although I believe they must be taken as proving that in high southern latitudes the surface temperature is sometimes lower than the temperature of the water at a considerable depth beneath, still the amount of correction for pressure is uncertain, depending upon the construction of the thermometers used, and in any case it must reduce the difference considerably. A large number of thermometers of the ordinary Hydrographic Office pattern were sent out with us, as I have already mentioned, in the ‘ Lightning,’ and these were of course the instruments used by Staff-Commander May for his temperature obser- vations. There was an opportunity of testing these thermometers, however, on the return of the vessel, 1 Recherches sur le Maximum de Densité des Dissolutions aqueuses. Loc. cit. CHAP. VIL. ] DEEP-SEA TEMPERATURES. 305 so that we are tolerably certain by actual experi- ment of the amount of their error. In speaking of the ‘ Lightning’ temperatures, I mean, therefore, the actual temperatures taken by the ordinary ther- mometers, corrected approximately to the standard of the Miller-Casella thermometers, afterwards used in the ‘ Porcupine.’ Leaving Stornoway in the ‘Lightning,’ on the llth of August, 1868, and directing our course towards the Froe banks, we sounded in 500 fathoms about 60 miles to the north-west of the Butt of the Lews, and took a bottom temperature of 9°4 Cent. with the ordinary Six’s thermometer— the only form of the instrument in use at the time. This, when corrected for pressure, gives about 7°8 C. We were surprised to find the temperature so high, and we were at the time inclined to think that the observation, which was taken in a breeze of wind, was scarcely to be depended upon. Subsequent observations, however, in the same locality, con- firmed its accuracy. On the Féroe Banks, at a depth under 100 fathoms, the bottom temperature averaged 9° C., while that of the surface was about 12° C.; temperature indications on this bank were, however, of little value, as the water is no doubt affected to some extent through its entire depth by direct solar radiation. The next observation was in lat. 60° 45’ N. and long. 4° 49’ W., at a depth of 510 fathoms, with a bottom temperature of —0°5 C., about 140 miles nearly directly north of Cape Wrath. ‘Then followed a series of sound- ings, Nos. 7, 8, 10, and 11 of the chart (Plate I), taken while traversing the northern portion of the x 306 THE DEPTHS OF THE SEA, [cHAP. VII. channel between Scotland and the F&éroe plateau; and giving, respectively, the temperatures of — 1°1, —1':2, —0°7, and —0°5 C. No. 9, with a depth of 170 fathoms and a temperature of 5° C., is excep- tional; it is apparently the top of a circumscribed ridge or bank. We dredged at this station and got large numbers of the rare and beautiful Zerebratula cranium ; but when we tried for the same spot in the following year in the ‘ Porcupine,’ we could not find it. On the 6th of September we sounded and took temperatures in lat. 59° 36’ N., long. 7 20° Weim 530 fathoms, when the mean of three thermometers, which only differed from one another by about °3 of a degree, gave a bottom temperature of 6°4 C. A temperature sounding, at the moderate depth of 189 fathoms, was taken on the morning of the 7th September in lat..59° 5’ N., long, 7 29° Wowaue gave a bottom temperature of 9°6 C. The three soundings, Nos. 138, 14, and 17, at the depths 650, 570, and 629 fathoms, extending into the North Atlantic as far westward as long. 12° 36° W., gave a bottom temperature of 5°8, 6°4., and 6°6 C., respectively. The general result of these observations we could not but regard as very remarkable. The region which we had somewhat imperfectly examined in- cluded, in the first place, the channel about a couple of hundred miles in width, with an extreme depth of rather under 600 fathoms, extending between the northern boundary-line of the British plateau and the shoal which culminates in the Froe Islands and their extensive banks; and secondly, a small portion of the North Atlantic extending westwards CHAP. VII. | DEEP-SEA TEMPERATURES. 307 and northwards of the western entrance of the channel. We found that in these two areas, freely communi- eating with one another and in immediate proximity, two totally different conditions of climate existed at all depths below the immediate surface, where they differed but slightly. In the Féroe channel, at a depth of 500 fathoms, the bottom temperature aver- aged — 1°-0 C., while at a like depth in the Atlantic the minimum index stood at + 6° C., a difference of 7 degrees Centigrade, nearly 13 degrees Fahrenheit. The conclusion at which we speedily arrived as the only feasible explanation of these phenomena was that an arctic stream of frigid water crept from the north-eastward into the Froe channel lying in the deeper part of the trough, owing to its higher specific gravity ; while a body of water warmed even above the normal temperature of the latitude, and therefore coming from some southern source, was passing northwards across its western entrance and occupying the whole depth of that comparatively shallow portion of the Atlantic from the surface to the bottom. Several important facts of very general applica- tion in Physical Geography had been placed beyond doubt by these observations. It had been shown that in nature, as in the experiments of M. Despretz, sea-water does not share in the peculiarities of fresh water, which, as has been long known, attains its maximum density at 4° C.; but, like most other liquids, increases in density to its freezing-point : and it had also been shown that, owing to the movement of great bodies of water at different temperatures in different directions, we may have in close proxi- x 2 308 THE DEPTHS OF THE SEA. [cHAP, VII. mity two ocean areas with totally different bottom climates—a fact which, taken along with the dis- covery of abundant animal life at all depths, has most important bearings upon the distribution of marine life, and upon the interpretation of paleeonto- logical data. The conditions during the ‘ Lightning’ cruise were so unfavourable to careful observation, that we deter- mined to take the earliest opportunity of going over this region again, and determining the limits of these warm and cold areas, and investigating their con- ditions more in detail. Accordingly, in the follow- ing year, when we had H.M.S. ‘Porcupine’ at our disposal, Dr. Carpenter and I once more left Storno- way on the 15th of August, 1869. On this occasion we had everything in our favour; the weather was beautiful, the vessel suitable, and we were provided with Miller-Casella thermometers on whose accuracy we could depend. Se: SOD © ,, S20 200 _ =C«ssy, fataats) 250M ws 5) Oa) 500s. ; OG 384 (Bottom) O58 We thus ascertained that the minimum tempera- ture was at the bottom; and this we have found to be universally the case over the whole of the area which we have examined, whatever the bottom temperature might be. And we also ascertained that the decrease in heat from the surface downwards was by no means uniform, but that while after passing the surface layer it was tolerably regular for the first 200 fathoms, there was an extraordinary fall amounting to upwards of 7 C. from 200 to 300 fathoms, at which latter depth the minimum is nearly gained. The next few observations, Stations 53 to 59, were all within the limits of the cold area, the bottom tem- perature at depths ranging from 360 to 630 fathoms, nowhere reaching the freezing-point of fresh water ; and at one point, Station 59, lat. 60° 21’ N., long. 5°41’ W., at a depth of 580 fathoms, the index stand- ing so low as —1°3C. On Saturday the 21st we took a sounding in 187 fathoms, on the edge of the F&roe a 10 THE DEPTHS OF THE SEA. [CHAP. VI. plateau, and about twenty miles north of the pre- vious station, with a temperature of 6°9 C., and so found that we had passed the limits of the cold basin. Our first two soundings after leaving Thorshavn (Stations 61 and 62) were in shallow water on the Feroe Bank, 114 and 125 fathoms, with a tempera- ture of 7-2 and 7-0 C. respectively; but the next Station, No. 63, after a run of eighty miles, gave 317 fathoms and 0°9C., showing that we were once more in the cold region. From that point, passing in a _ south-easterly direction across the channel towards the northern point of Shetland, we traversed the cold area in its most characteristic form, finding at Station 64, lat. 61° 21’ N., long. 3 44° W., a depth of 640 fathoms, with a bottom temperature of —1°2C. Here we took another serial sounding, and its results corresponded generally with those of No. 52. The surface temperature was . lower, and the temperature down to 200 fathoms some- what lower; at 350 fathoms it was a little higher :— SUPEACE) oy. Sc a ees hae oe ee S0fathonmis’.< 2° 0.25 7-5 eae ee 100). 3 we AG a Ts a a LO ae rill cass APO cee ee Ge 200i? ve. 4-4 2505 er ee a ee OE OOK we. oat fg 8) im Re A es SKU mare . aw ee Sees 400 Pe DAs!) oo eee ORS 450, 0-8 500 Es -1:0 Ho Ouower., ee ee a tL AUC), rar ene LE ET Tt 640 a OS ER ee aa ae eo, cuar. vi] DEEP-SEA TEMPERATURES. eal At this point, therefore, the ice-cold water of the Arctic current filling up the bottom of the trough is nearly 2,000 feet deep, while the temperate water above has nearly an equal depth. The lower half of the latter, however, has its temperature considerably reduced by intermixture and diffusion, Fig. 55 represents diagrammatically the general result of temperature observations in the cold area. ‘The depth at the next Station, No. 65, was 354 fathoms, showing that the channel had begun to shoal towards Shetland; the temperature was, however, still low, almost exactly 0° C. The next Station, No. 66, eighteen miles further on towards the Shetland banks, gave a depth of 267 fathoms, with a bottom temperature of 7° 6 C., the temperature at the surface being 11°3C. We had therefore got beyond the edge of the trough filled by the cold stream, and passed into lesser depths occupied from the surface to the bottom by the warm southern stratum. The next series of soundings, Nos. 67 to 75, are either in shallow water round Shetland, or in water on the shelving edge of the plateau, not deep enough to reach the frigid stream. It is of some interest that the two soundings, Nos. 68 and 69, in 75 and 67 fathoms respectively, to the east of Shetland, show a bottom temperature of 6°6 C., while a serial sounding in the warm area at the western entrance of the Fwéroe Channel gives for the same depth a tempera- ture of about 8°8 C. This circumstance, along with others to be mentioned hereafter, would seem to show that a considerable indraught of cold water spreads over the bottom of the shallow north sea. At Stations 76 to 86, which are along the southern JJ iia ~Servial Sounding, Station G4. FIG 96, —Serial Sounding, Station 87. CHAP, VII. ] DEEP-SEA TEMPERATURES. ale border of the cold area, temperature soundings were taken mainly with a view to define its southern limit, and they are sometimes on one side and sometimes on the other. The general result is indicated on Plate IV. by the southern border of the shaded space. Nos. 87 to 90 are once more in the warm area, the water reaching a depth of upwards of 700 fathoms, but maintaining, after the first 500 fathoms, a tempera- ture of from 6° to 7° C. above that of corresponding depths in the cold area. At Station 87, lat.59°35'N., long. 9 11’ W., with a depth of 767 fathoms, a serial sounding was taken, which contrasts remarkably with the series at Station 64. The general result of this sounding is represented diagrammatically by Fig. 56. The temperature was taken at every 100 fathoms after the first 200. RAC ORMOAEE 00 tata aa Se ol Mog" ee ALG. SOGEVUIMOMIS, sj... Seale Sk hier HOO >, opnoms M5O= 4 os 200... Oye a0 Uae» s, toler aL 400 ; (RS D00y (Panes) 600 —,, 61 BOTs ‘sy ae! It will be seen by reference to the chart that two nearly parallel series of soundings were taken, ex- tending from the shallow water on the Scottish side to the edge of the Feroe Bank close to the western opening of the Fiéroe Channel, and that one of these chains, including Stations 52, 53, 54, and 86, is in the cold area, while the other chain of Stations, 48, 314 THE DEPTHS OF THE SEA. [CHAP, VIT. 47, 90, 49, 50, and 51, is in the warm area. There is no great difference in depth between the two series of soundings; and there is no indication of a ridge separating them. The only possible explanation of these two so widely different submarine climates, existing apparently under the same circumstances and in close proximity to one another, is that the Arctic indraught which passes into the deeper part of the Féroe Channel is banked in at its entrance, by the warm southern stream slowly passing north- wards. There is a slight but very constant depres- sion of the isothermal lines of surface temperature in the shallow water along the west coast of Britain. This, I believe, indicates that a portion of the cold Féroe stream makes its escape, and, still banked in close to the land by the warm water, gradually makes its way southwards, so mixed and diluted as only to be perceptible by its slight effect on the lines of mean temperature. Diagrams 55 and 56 illustrate the dis- tribution of temperature in the cold and warm areas respectively ; and in Fig. 57, the results of the serial soundings Nos. 52, 64, and 87, are reduced to curves. From these diagrams, taken together, it will be seen that in the first 50 fathoms there is a rapid fall of nearly 3° C. Station No. 64 is a good deal farther north than the other two, and the surface tempera- ture is lower, so that the fall, which is nearly to the same amount, starts from a lower point. The surface temperature is doubtless due to the direct heat of the sun, and the first rapid fall is due to the rapid decrease of this direct effect. From 50 to 200 fathoms the temperature in all three cases falls but little, re- maining considerably above the normal temperature , PUL .-ULIVA, OI[} UL SSULPUNOS [BIS ULOIy popon.AysuC 201M Y PUB PULBTJODS W9aM Jaq [OUUKYO 9} UL , S¥aTE-plOD 316 THE DEPTHS OF THE SEA. (CHAP. VII. of the ocean for the parallel of latitude. At a depth of 200 fathoms, however, the divergence be- tween the curves of the warm and cold areas is most remarkable. The curve of the warm area, No. 87, shows a fall of scarcely half a degree at 500 fathoms, and less than one degree more at 767 fathoms at the bottom. Between 200 and 300 fathoms the cold area curves run down from 8° C. to 0° C., leaving only one degree more of gradual descent for the next 300 fathoms. The temperature of the ‘hump’ on the curves of the ‘cold area’ between 50 and 200 fathoms corresponds so nearly with that of the long gradual sinking of the curve of the warm area from the surface nearly to the bottom, that it seems natural to trace it to the same source. We there- fore conclude that a shallow layer of Gulf-stream water drifting slowly northwards overlies in the cold area an indraught of cold water represented by the sudden and great depression of the curves, while in the warm area this cold indraught is absent, the Gulf-stream water reaching to the bottom. Tracing the ‘warm area’ southwards from the mouth of the Féroe Channel along the coast of Scot- land, we find that the area between Féroe, the Lews, and Rockall, is a kind of plateau with a depth of from 700 to 800 fathoms; and we may be certain from analogy, although this region has not yet been actu- ally examined, with a bottom temperature not lower than 4°5 C. Commencing opposite Rockall, and ex- tending between the great shoal which culminates in the Rockall fishing banks and the singular isolated rock, and the west coast of Ireland, there is a wide trough deepening gradually southwards, and at length CHAP. VU.] DEEP-SEA TEMPERATURES. BLE continuous with the general basin of the North Atlantic. The temperature of this ocean valley was investi- gated with great care during the first and second eruises of the ‘ Porcupine’ in 1869, and the results were so very uniform throughout the area that it will be needless to describe in detail the slight differences in different localities. These differences, in fact, only affected the surface layer of the water, and depended merely upon differences of latitude. The temperatures in deep water may be said to have been practically the same everywhere. The first chain of soundings, taken by Captain Calver during the first cruise under the scientific direction of Mr. Gwyn Jeffreys, was between Lough Swilly and Rockall. The greatest depth, 1,380 fathoms, is in the middle of the channel, and a sounding at that depth, lat. 56° 24’ N., long. 11° 49’ W., gave a bottom temperature of 2°8 C. A depth of 6380 fathoms, No. 28, a little to the south of Rockall, gave a temperature of 6°4 C., almost exactly the same as the temperature of a like depth in the warm area off the entrance of the Féroe Channel; and a temperature at 500 fathoms, one of a series taken at Station 21 with a bottom temperature at 1,476 fathoms of 2°°7 C., was 8°5 C., rather less than a degree higher than the temperature at a correspond- ing depth at Station 87. At Station 21 the tempera- ture was taken at every 250 fathoms. SUDRYGO. 6 Soe ig a og b0 5 Pe a Oe DAVIN 6 ceo 6 oe 8 oe eon oS 9:0 500 Way oc, 5, ee es, 8 Sirs ” 5 HO one Be i lor ES EO) on 2 OR 318 THE DEPTHS OF THE SEA. {CHAP. VIL. 12000 tathontsws: JAS GE) Oa Ee Roane 1a ae hh oni aL ee LANG. 25 Aparna Geran sree a OL We have here on a large scale, as Dr. Carpenter has pointed out, conditions very analogous to those which exist in comparatively shallow water, and on a small scale in the cold area in the Féroe Channel. There is a surface layer of about 50 fathoms, super- heated in August by direct solar radiation, and, as we see by the variations of surface isothermals, varying ereatly with the seasons of the year. Next, we have a band extending here to a depth of nearly 800 fathoms, in which the thermometer sinks slowly through a range of about 5° C. Then a zone of intermixture of about 200 fathoms, where the temperature falls rapidly, and finally a mass of cold water from a depth of 1,000 fathoms to the bottom, through which, what- ever be its depth, the thermometer falls almost im- perceptibly, the water never reaching the dead cold of the Arctic undercurrent in the Féroe Channel, and the lowest temperature being universally at the bottom (Fig. 58). The area investigated during the second cruise of the ‘Porcupine’ at the mouth of the Bay of Biscay, about a couple of hundred miles west of Ushant, may be regarded as simply a continuation southwards of the tract between Scotland and Ireland and the Rockall ridge. As, however, the depths were greater than any attained on any former occasion—were so creat, indeed, as probably to represent the average depth of the great ocean basins—it may be well to describe the methods of observation and the condi- tions of temperature somewhat in detail. 320 THE DEPTHS OF THE SEA. (CHAP. VII. The sounding at Station No. 37, at a depth of 2,435 fathoms, has already been fully described as an example of the most recent method of determining extreme depths with accuracy. Two Miller-Casella thermometers, numbered 100 and 103 respectively, . were lashed to the sounding-line in their copper cases, one a little above the other, about a fathom and a fathom and a half above the ‘Hydra’ sounding- machine. These two instruments had been prepared. and tested with extreme care, and had been employed throughout the first cruise; their freezing-points had been again verified at Belfast in case the enormous pressure to which they had been subjected might have affected the glass, and we had absolute confidence in their indications. The indices were set before the instruments were let down at the temperature of the surface, 21°°1 C., and 21°15 C. They were allowed to remain at the bottom for ten minutes, and on their return to the surface in upwards of two hours and a half, they were unanimous in recording a minimum of 1°65 C., the slight differences between the two instruments, which gave the almost inappreciable error for one of them of 0°05 C. at 21° C., being imperceptible at the lower temperature. It had a strange interest to see these two little instruments, upon whose construction so much skilled labour and consideration had been lavished, con- signed to their long and hazardous journey ; and their return eagerly watched for by a knot of thoughtful men, standing, note-book in hand, ready to register this first message, which should throw so much lght upon the physical conditions of a hitherto unknown world. CHAP. vIn] DEEP-SEA TEMPERATURES. 39] A series of temperature soundings, at depths m- creasing progressively by 250 fathoms, was taken to a depth of 2,090 fathoms, on the 24th of July, lat. A 39 N., lone. 11° 33’ W. Surface . . 17°: 08C. 250 fathoms. 10° 28 less than Surface . . 7°: 5C. 500 &; 738 53 250 fathoms. 1° 5 (3) aeer VON rg 5 500, 3)-.6 L000 ,; 3° 5 , 750R t. tO 1250) —., 3-17 - 1,000). 0:3 1,500 ,, 2+9 2 eneee 0-3 G50. 25 P61 sf 1500) 3) OLS 7 UE) ee 2°4 - bE) ok 0-2 The same two Miller-Casella thermometers were employed as in the previous observation. Another serial sounding was taken a few days later in water 862 fathoms deep, somewhat nearer the coast of Ireland. In this case the temperature was taken at intervals of 10 fathoms from the surface to a depth of 50 fathoms, and thence at intervals of 50 fathoms to the bottom. ‘This was done to deter- mine exactly the rate of diminution. of tempera- ture, and the exact position of the most marked irregularities. Suniace, = .. 17-2 22.C. 1Ofathoms., 16° 72 less than surface . Uae &- 74 a Hoel 22 less than 10 fathoms. 1° 5 2; Uae ye linseOer is: r 2005 2. cele OE 2 AD ad a 30> 3 = 0,59 Sve. eee) Mea cri oes e cy) ees LOODs es. EO. 6 ; Ose ae de 50) git. ees Lome ., 0-1 200! = me hOR 3 3 150 = LOGsS DO eo etl a 2007 age (ea 300" ~ 5; a Ee eS . 250, .) ORNS Wisp) Fre. 60.—Diagram representing the relation between depth and tent- perature in the Atlantic basin. Fic. 59.—Diagram representing the relation between depth and tem perature off Rockall $e: Se Pirate VI.—Diagram of the § Porcupine’ soundings in the Allantic and in the Faeroe Channel, showing the relation between temperature and depth,—the serial soundings reduced to curves, The numbers refer to the stations on the Charts, Plates II, IITI., and IV. Ti 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 - 1500 1600 1700 1800 1900 emp. 2000 — 2100 2200 2300 2400 Fathoms ———= T C o | | | 2 _ 2100 2200 2300 2400 FKathoms 0 50 =: 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 $700 {800 1900 2000 ed 00 ——L cHaP. vil.] DEEP-SEA TEMPERATURES. 393 350 fathoms 9°-5C. lessthan 300 fathoms. 0°: 3C. 400, 25-47 , 350, 0-3 eae 8-7 ; oe sO 5 500, 8-55 E 450 , . 0°15 550, 8-0 2 500, 0-55 600, 7:4 : ee oe 650, 6-83 a ene 66 MG? ee 4h, 650, 0-4 50 , -Med- 83 = 700, 0-6 300... ,,. utr aD DS e 750 0-3 862 (Bottom) 4°3 f 800 1-25 The general result of these two series of soundings _ is very important. The high temperature reduced by 7°5 C. in the first series at 250 fathoms is undoubtedly due to superheating by direct solar radiation. This is shown still more clearly in the second series, where nearly 4° C. are seen to be lost between the surface and 30 fathoms, and somewhat above 2° C. more between 30 and 100 fathoms. From 100 to 500 fathoms the temperature is still high and tolerably uniform, and it falls rapidly between 500 and 1,000 fathoms. A reference to the second series shows that this rapid fall is between 650 and 850 fathoms, in which inter- val there is a loss of more than 3°C. ‘This second stage of elevated temperature from 250 to 700 fathoms, which is represented graphically by the singular ‘hump’ on the temperature curves in Fig. 61 and Plate VI. would seem to be caused by the north-easterly reflux under peculiar conditions, which will be referred to in next chapter, of the great equatorial current. From 1,000 fathoms down- wards, the loss of temperature goes on uniformly at the rate of about 0°38 C. for every 250 fathoms. The most singular feature in this decrease of tem- y 2 1 jULTLV et} Ul sSuipunos sinqzeredure4 u | PUB [VILLAS WOIJ paJNASMOD SAAIND—"T9 ‘OI CHAP. VII. ] DEEP-SHEA TEMPERATURES. oe perature for the last mile and three-quarters is its absolute uniformity, which appears to be incon- sistent with the idea of anything like a current in the ordinary sense, and rather to point to a slow and general indraught of cold water, falling in chiefly by gravitation from the coldest and deepest sources available, to supply the place of the warm water constantly moving to the northward. In 1870, Mr. Gwyn Jeffreys took his first tem- perature observations at the mouth of the Channel, and found them to correspond very closely with those of the previous year; on the 9th of July the bottom temperature at 358 fathoms, Station 6 PI. V., was 10°0C., against 9°°8 C., at about the same depth in a serial sounding in 1869, in the immediate neighbourhood. The next few soundings, Stations 10 to 18, are in comparatively shallow water, off the coast of Portugal, while the next four Stations, a little north of Lisbon, may serve as an example of the temperatures to a considerable depth in that latitude. Station 14, 469 fathoms, with a surface temperature of 18°3 C., has a bottom temperature of 10°7 C.; Station 15, at 722 fathoms, a temperature of 9°7C.; Station 16, at 994 fathoms, 4°4C.; and Station 17, at 1,095 fathoms, 4°3C. This result is very similar to that which we met with in 1869 off Ushant. With certain differences, which seem to de. pend mainly upon the differences of latitude, we have the same phenomena—a thin surface-layer, superheated by the direct rays of the sun; a layer of warm water through which the temperature descends very slowly down to 800 fathoms; a zone of intermixture and rapid descent of the thermometer of nearly 200 326 THE DEPTHS OF THE SEA. [cHAP. VII, fathoms in thickness ; and finally the deep cold layer into which these soundings do not penetrate very far, through which the temperature sinks almost imper- ceptibly from 4°C. The difference between these soundings and those of the year before at the mouth of the Bay of Biscay is that the temperatures at all depths are somewhat higher. I refrain for the present from going into any detail with regard to the distribution of temperature in the Mediterranean, further than to give a mere outline of the remarkable conditions which were observed there by Dr. Carpenter. Dr. Carpenter’s observations were principally con- fined to the western basin of the Mediterranean, and during the months of August and September the surface temperature averaged between 23°C. and 26°C. On two occasions only the surface tempera- ture fell considerably lower, and the fall was attri- buted in both cases to the influence of the colder surface current passing from the Atlantic through the Straits of Gibraltar. The following table of the series taken at Station 53 gives about the average rate of fall of temperature for the first 100 fathoms :— DUTlace. <7 0 era se ae eee ea ee 252° OIC: De fat NOINS ie ws 2), ee eet mn ne heal OAS. Fae RG aie UND Mey fic) me INL) DP) & >, Sahel NS ORT EA chee 1a BER Mle: 30m, CN ian 20 eel teh ae elon 40 em Seman re ey eee Lor 50 ms Ne TRS fk oy ec LG LOO ray eg. ye ay Ria (0) and Dr. Carpenter made the remarkable observa- tion that “whatever the temperature was at 100 Fic. 62.—Diagram representing the relation between depth and temperature, from the tempera- ture observations taken between Cape Finisterre and Cape St. Vincent, August 1570. > 328 THE DEPTHS OF THE SEA. [CHAP, VII. fathoms, that was the temperature of the whole mass of water beneath, down to the greatest depth explored.” The temperature at 100 fathoms varies very little from 138°C. (55°5° Fahrenheit), and the Mediterranean attains in many places a depth of up- wards of 1,500 fathoms, so that here we have the strange phenomenon of an underlying mass of water, 1,400 fathoms deep, of a uniform moderate tempera- ture; a state of things singularly different from that which obtains at like depths in the Atlantic. Dr. Carpenter’s ingenious speculations as to the cause of this difference will be considered later. VAAY CHURCH IN SUDERO. CHAP. VII. } DEEP-SEA TEMPERATURES. APPENDIX A. 329 Surface Temperatures observed on board HMMS. ‘ Porcupine’ during the Summers of 1869 and 1870. I. TEMPERATURES OBSERVED IN 1869. | 2 | seell Sa Be he eal aes | Date and Position. iS ae 2% | Date and Position. = 25 oe | > Bo .| &3 | fo ao | 33 | Be | Be | oT es Deg. Deg. Deg. Deg. Cent. Cent. || Cent. Cent. May 28th . . 2 | 100 94 | May 30th 4 | 100 9°4 4+ 10°;0 |} 102 6 10°8 | 10°8 6 8 122 | 11-1 | 8 10 T5507 | | 10 | 10:0 | 10°5 || In Valentia . Noon.| 15°0 | 12-7 | Of the Great ; Ze S| eo Skelligs ee eee 4 | 195 | 11-4 2 11°9 6 114 | lil | 4 LCG lalla 8 6 11°4 || LO) | 10:0) |) 1-7 8 | Midn.| 9°4 | 11°1 10 116. | 10°2 | May 31st. 2 9°4 | 10°8 Midn.| 10:0 | 10°5 4 OSO ete: May 29th . . 2 ] 6 ia | a1 4 (7% | 8 13°3 j Ill 6 116 | 102 10 133; ) VET | 8 | Wy | 108 Gat. 51°52’ NN.) | ; | 10 |-13:3 | 12-7 || Long, 11°34 w. 5 | Noom-| 189 | 11°6 In Dingle Bay . | Noon | 13°99 | 11°6 | 2 | 139 | 114 2 13°9 11-4 | 4 12°7 4 1257 11°4 6 12:2 | 11°9 6 10°5 8 122 >|) EG 8 1070 | 10°5 10 Loy LIENS | ROS let | Midn.| 11°9 | 11°9 Midn.| 1171 | June ist . De | DSO ll 2 7 4 Zia lee, May 30th . .. 2 |) VEG 330 THE DEPTHS OF THE SEA. [CHAP. VII. @ ae |i © od 5 Bs £5 5 Be Ee Date and Position iS 24 Bie | Date and Position. iS = z% ED Sel eee BP | ee Deg. Deg. || Deg Deg. Cent Cent. || Cent. Cent. June Ist . 6 | 122 | 11:9 || June 4th . 2 | TS Se eee 8 SiO atalOin|| 4 Nei} jf Ib) 10 SOM elo || 6 IPs) |] UES) iaite ollie: 22MIN): Ate : 8 1258. 2e2 Long. 12° 26 W. SSE UE TIED 10 | 122 | 11-4 2 144 | 122 || Midn.| 11'9 | 11:9 4 12°2 | 11°6 || June Sth . 2) lO lS 6 13°3 | 11:9 4 1E6 116 8 [22 169") 6. | 127 eel LOD RO esa 8 | 12 eee Midn.| 11°6 | 119 || 10 Ue |) AIG June 2nd, 2 | 119 | 11:9 || In Galway Dock | Noon.| 1671 | 13°3 4 ila 11°9 2 ists) |) Hay, 6 10°5 | 11°9 4 139 8 116 6 155 10 22 | D2 8 13°3 Lat. 52° 8 N. | 10 | 13°3 Long. 12°50’ W. (| Noon) 150 | 122 Midn. 13-9 2 | 144 | 122 || June 6th. 2 eee 4 Is (0) 11 4 Py 6 ISH). | Ie 6 8 iil 11:9 8 10 11°4 | 11°9 10 14°4 | Midn.} 111 | 11°9 || In Galway Dock | Noon.| 12:2 June 3rd . | 2 iibeil 11°6 2 172 | 4 KOS} |) WLS 4 19°4 6 ILA 11°9 6 19°4 8 a7 ales 8 10 15:0 | 11:9 10 13°9 Tat. 52.260 IN) Ss er Midn.} 13°3 Long. 11°41’ W. § Noon ty 3) tee. |) sane 7th 2 lars 2 W471) 11-9 || t WAT 4 13°0 | 12°2 6 6 THE |) PA 8 8 111 11°8 10 1671 10 | 111 | 11°6 || In Galway Dock | Noon.| 18°3 Midn.| 10°8 | 11°6 2 yg June 4th . | Waleik |) Tales AS el Tia 4 tal 11°6 6 17:2 6 iyi 11°6 8 150 8 10°8 | 11°6 10 13°9 7 10 10°5 | 116 Midn.| 12°2 ats, "52. 140 oN : . June 8th . 2°. | ot Tone, ease jcon| 205) 14 4 | 10:0 CHAP. VII. | DEEP-SEA TEMPERATURES. 331 4 | £2 | £8 H | Ze | #5 Date and Position. e aS 27 Date and Position. g ae are Fed Bu ES £5 & ere & apa Deg. Deg. Deg. Deg Cent. Cent. Cent Cent. June 8th . 6 | 10:0 June 11th 6 | 119 | 12-7 8 8 NO) 7 10 A/S 10 ites 12°2 In Galway Dock | Noon.} 21°1 | | Midn.| 10°0 | 12°2 2 | 905 June 12th 2 | 100 | 12°9 4 20°5 Wefeeh Ih 4 10°2 12°3 6 20°0 6 Lita 12°9 8 166 | 15:0 8 Aes eiltess( 10 IEG ea 3 N) MO ae 22 7/ Midna) ices suai at. 53°24" Ni aoe ; June 9th . 2 rico |) be Long. 15° 24 W. {| Noon.) 12°2 | 12°7 4 for) 11°6 2 SN 1ST 6 10°5 DD, 4 14) IP 7/ 8 19-7 | Bib 6 1O38> |) 130 10 16°1 13°3 8 atales 12°9 In Galway Dock | Noon.| 19:4 | 13°9 LOW) dae 1a -5 2 17-4 | 139 Midn) 10:5) | 12:3 4 17:2 | 13°6 || June 13th Ph |) ARS, I, alee. 6 15:0 | 12°5 4 NOOR alo) 8 Iie |) ee 6 eal | Tee 10 10°55 | 12°5 8 9°7 | 11°9 ‘ Midn.| 10°5 | 12°5 = 10 9°4 | 12°0 June 10t 2 | 1070) |) 11°6) |) Lat. 537287 Ne) ; . 4 | 10:5 | 11°6 || Long. 15°08’ W. 5 | Noom-| 10°8 | 12°2 6 16:2 | 1o32 2 10°5 E25) 8 OJ 12°5 4 11°4 | 12°2 7 = 10 ISG eles 6 Tey LE, at. 53° 16'N. 8 | 10:7 | 123 Long. 11° 52° W. Noon.| 127 | 125 10 | 111 | 12°2 2 NES} 4) RY Midn.| 11°1 12:2 4 122 | 12°2 || June 14th 2 Aiee> |) 119-9; 6 IGG ale 4 TCS aD) 8 LO) -\) Lass 6 Tee tet 9) 10 10:0 | 12:3 8 1D9) 2:5 j Midn.} 10:0 12°3 10 qlee 1D, une 11th 2 | LOO | reel Eat: 53°40 N. ) < oe 4 | 100 | 122% || Long. 13°49’ W, }|Noom-} 133 | 12°2 6 WAPI VAs: 2, 7 sy 8 Hl TDS 4 130 12°2 = Sone 10 12°5 12°5 6 EF 12°2 ate os 22 Ni : a 8.) | dale As Long. 13° 23’ W. § Noon.| 15:0 | 122 UIC O ag fl Bs hae STEP 2, Bee | alee | Midn.| 11°] 11°4 4 | 144 | 12°7 || June 15th 2. 108 Plast 332 THE DEPTHS OF THE SEA. [CHAP. VI. Date and Position. 3 Spe oe Date and Position. = ed r= eal gee B° | Ba B ss = nite Deg. Deg. | Deg. Deg. June 15th 4 | tos | 116 | Lat. 54°10°N. ) ee une lv ite i | at, Vv . | 9: Dee 6 | 111 | 11°6 || Long. 10°59’ W. 5 | Noon.| 125 | 122 8 144) 6 | 2 ae |. 129) 10 12:3 |) L1s6 4 127s ret Lat. 53°47 N. ae yi 6 NERY || Wile Long. 13° 14 W. Noons| as 0G g | 11-9 | 118 2 13:6) sG 10 LAA eIcG AL | 13:0") E156: | Midn.| 11°4 | 11°4 6 139 | 11°8 || June 19th 2 LT SSL tbls 8 LOS) Es 4 ET SIL 10 10°8 | 116 6 ANOS} Ts) Midn.| 10°5 | 11:1 8 MAL ay |) Wee. June 16th 294 NOs ea a 10> | 13;9) aes 4 | 102 | 11:4 | At Killibegs. Noon.| 13°9 | 11:9 6 157 | eo 2 13°3 | 12:2 8 12509) co 4 12:2 | 122 z 7 10 1359) EG 6 116 | 123 at. 54° 2 N. a ee 8 | 130 | 12°7 Tere, Toe ee | || Le) se 10 | 111 | 122 2 13:9) 119" |i) Midn.| 10°5 | 122 4 13°3. | 12°1 || June 20th 2 LOSS a HES 6 PE ILIIEG: 4 Vs) 5) EG 8 NO De ey 6 NLS) |) JUTE 10 TANG) eabile4s 8 12°77 | 12:2 Midn.| 11-4 | 114 | 10 TSO ES June 17th 2 | 116 | 116 | At Killibegs. Noon.| 13°9 | 12:2 4 11-6 | DEG fll 2 ASO) || 2A 6 1 Ns 4 144 | 12°5 8 1356S els6 6 14°4 | 12°5 10 2 ela: 8 12°2 | 12°5 Lat. 54°27'N. )| 10 | 10:0 | 12°2 Tone mae epi ty (OB | ales) 'Midn.) 10°8 | 12°5 2 | 133 | 119 || June 2ist | 2 4) Piet See 4 13739) 119 4 able || alsa 6 Wey) TL) 6 aS 3) |) ZF 2 8 22 als 8 POs2 We Mee 10 19> | 116 - || 10 13:0 |-12°2 Midn.| 122 | 11°6 | At Killibegs. Noon.) 15°0 | 12°5 June 18th 2 16. }) 161} 2 153 | 12°2 + TAG L250. 4 144 | 12°5 6 122 | 12°0 6 13-0 ee Seal22) |) 19 | & |-11-6.| as 10 1252) |) 12:2 10 Waites |) IIL} CRAP. VII. ] DEEP-SEA TEMPERATURES. 5 Be a oS sy Se} Date and Position 3 24 one | Date and Position. | a =5 es | ) oN | = | Deg. Deg. | Cent Cent. | June 21st Midn.| 10° | 12°22 | June 25th June 22nd ie Dn OL ay) dels 4 lil 119 6 WET 116 b> Sida o-000 | 10 | 133 | 122 | June 26th At Killibegs. | Noon.| 13°3 | 12:2 2 13°99 | 12:3 4 PSS 22 6 12°2° | 12:2 8 | In Donegal Bay | 10 1A | 125 Mubeolny)) Teil |) anes) June 23rd Fetal ORS | EY 4 TMH 12°2 6 12°4 | 12:2 8 13:9 | 12:2 || 10 | 155 | 125 || June 27th At Kaillibegs. Noon.| 16°6 | 12°5 | 2 15°5 PS) [eee lee icrzae | peal ) 6 Wee) a3: || 8 13°3 | 13:0 | At Killibegs. 10 136 | 13:3 || | Midn.| 12°7 | 130 | June 24th ee 2 MO TSS 40 | 184) 133M 6 ae SE | 8 tay} IRS 4] 10 | 166 | 135 || June 28th At Killibegs. Noon.| 17°5 | 13°5 | 9 Ne | Aso 4 4 viral | 141 6 Li7fPAe |) IUESRO) 8 161 14:1 That: 54°54" Ni 10 | 147 | 15°0 || Long. 10°59’ W. | Midn.| 14°7 | 15°3 || June 25th | Deira aes 4 14°] 14°4 | 6 | 139 | 136 |] 8 18°3 | 144 || 10 20°0 | 13°9 | At Bundoran | Noon.| 20°5 | 16°6°|| June 29th lp 8 23:9 | 166 — by 2h a ° Deg. | Deg. | Cent. | Cent. 4 | 15:0 | 15:0 6 | 1671 | 13:9 S| 15:0 ie 108 | 1555165. | Midn | 14°4 L535 | Oe eka eras: | 4--| 13:9 | 15-0 6} 139 N83 § (1s3. | 136 10 | 180 | 14-4 Noon. Oso s9 Q | 99°2 | 153 4 | 194 | 161 6 | 166 | 155 8 | 155 | 155 LOS T2e0 | Woes 'Midn.| 12°5 | 15:0 98 | Dil | ia || Ah Sea aaa | 6 lee 139) | 8 | 136 | 13:9 10 | ob: | 142 4 Noon.| 16°6 | 14:4 | 2 | 20:0 | 15-0 | 4 | 172 | 144 6.1331 183 g | 133 | 133 10) sles | 1354 Mirdnsintso i 33 Pa OT dln daa 4 | 127 | 12:9 6 wer |eoe7 gs 13-2 (piso 10 | 139 | 133 Noon.| 14°7 | 13°3 9 | 14 Nese 4 | 139 | 133 | 6. | 13: s90 8 | 13-6 13-0 !. 10> «| 19°72 |) 1333 | Midn.| 129 | 13°6 2 | 12°7 13°3 a Oe ey: 304 THE DEPTHS OF THE SEA. [cuAP. VI. ao- ee Date and Position. e . 26 am Date and Position ie ae z4 = aS =o =» | a are ! | = Bs | (Se | | eas a Deg Deg. i Deg. Deg Cent Cent. |] tent. Ceut June 29th . . 6 | 136 | 13:3 || July 2nd . 4 162 2)5 | a2 8 14:4 113333} 6 ays) 14°5 10 16°6 13°9 8 147 14-4 Deke, fay Wa NYS 7) e rel 10 15: O26 Morena we yhoo) Lee es Midn.| 14:4 | 139 9 | 16m | wero. || July srdicr.. 2 13:9) | U39 4 15°5 14°4 | 4 13°3 13°9 6 15°5 14-4 6 14:9 141 San lis Oe aa ee 8") sss a eee 1) 13°6 139 L = 10 161 140 | Midn.| 13°3 | 13°9 at. 56° 58’ N. ( : | June 30th’. . 9 | 13:0 (| wat |) bong: ls air’ Wes Noon.| 153 | 13°9 4 13'°3 14:0 2 16°99 | 14:4 6 16:6" | V9 4 ASL || SHY) 8 SOM Seo 6 14:7 | 136 7 7 10 161 14-4 8 139 12°5 at. 55°44’ vi 10 13°3 12°5 Long. 12°53’ W Noon.| 16'4 | 14°4 Midn.| 12°7 | 12-2 2 \177 | 145 || July 4th. . . 2 | 13-4 | 136 4 Welz 14°4 || 4 13°9 | 139 6 15°8 1550) 6 13°6 14:0 8 TSSOP SEO: 8 14:1 13°6 10 144 | 15:3 || x 10 14°7 14:7 Midn.| 13°6 | 14:4 || Lat. 56°47 N. }| : | July Ist... 2 | 127 | 13-9 |) Long. 12° 49° W. Noon. |b 05 aee 4 13°3 13°9 || 2 144 laa 6 15°5 14°4 4 144 | 148 8 16°3 14°4 6 139 | 14:8 10 ys |) We e7 8 13°9 | 149 Noon.| 172 | 14:8 10 139 | 1 2 IPA |) lise Midn.| 13°3 | 14°7 4 1656. 15:0 || Sully bth Se 2 | V2) ae 6 15:0 14°4 4 13:3) 15:0 8 14:4 14-4 6 13°9 14°7 | LOU | Ws) a 8 | 139 cae Midn.| 1471 14:1 a 10 14:4 | 14:7 | duliye2indie 7 acs De t4at. |) 13:9) ||| Tat. (56: 4p ' | 4 | 141 | 140 || Long. 12° 56 W. Neon. eae | 6 WoO) Was 2 144 | 15:0 8 155 | 141 | 4 11353) doo 10 155 14°4 6 12°7 14°4 || Hat: “562 19/ Ne) 3 8 12°2 14:1 | Long 14° 10’ W. \ Noon 17 Ul 14°4 Bi 174-147 || Midn.| 125 | 14-4 | 10 | 12:5 | 14:4 CHAP. VII. ] DEEP-SEA TEMPERATURES. io) oS or Date and Position July 6th . Matenn6 22% IN. Long. 11°37’ W. § July 7th . Ones Lat. 55°55’ N. ) Long. 10° 17' W. § July 8th . tate 56° 6 N. |) Long 9° 36’ W. || July 9th . | | | 2 zo i 2 2g S zo ae 1 Date and Position | e ae Ba ) on || | D ow a Be || a Bs | Deg. Deg Deg. | Deg Cent Cent : ‘ent Cent 2 | 12:2 | 13:9 || In Lough Swilly | Noon.| 15°8 | 13:3 AO W127 9) Be Teale) sis 6 | 124 | 138 | A 55 1 13°0 Si jel3'9) nasi 6 5" | 13:3 LO | Pat W13-9 8 | 13°99 | 133 a LOO Poets: Noon. 13 | Midn.|-11°6 | 12-7 25-0 | July 10th 9 Deis 1:6 4 \el5:3 |) 4-7 1) 47 | 19:9= 1 13:6 6° | 13-9) | 144 Go see 13-0 Sela ete S: || UGe ie ela! 10 12°0 | 13°9 10 1671 | ia-4 Midn.| 11°1 | 13°3 || In Lough Foyle | Noon.| 17°7 | 14:4 P77 3) TSS tt 2 Die Tao Ai | 14 ses AY 1853 lees 6 | 1470 | 1333 | 6 | 161 | 144 8 | 147 | 133 | 8) tea aS-6 LO) | DSO tS (= 10! aso. 333 ae Ye | | Midn.| 14:4 | 13:9 Noon.) 15°0 | 13°31! July vith | 2 | 150 | 14-4 2 ESO) TBS) } az 13:9) 4) 144! 4 | 150 | 136 | | = siGe eaacs* | Oisee) 6 |. 15:0 1) 18:9 || 8. | di63 (13:9 8 | 15:0 | 139 || | 10 | 166 | 136 10 | 144 | 13:3 || At: Moville, aie f ; Midn.| 14-4 | 13°3 || Lough Foyle § Noee ae ie 2 | deal | 53°97 Gy) 2 | 205 | 15°5 A | 4-4 13:6 lel 50 6 | 155 | 13:9 6 | 189 | 14:4 8: 1 15a kiSo Se (80) | 1454 10 | 150: _|-13°9 10 |} 15:8 |: 13-9 ee eal Midn.| 15°8 | 14°4 NGO TOS ACrea rally Wott | 2 | 15:3 | 15-0 2 147 13-64 Ads [pkey AR Oe Ss6i i Gee Sole | ae: 6 183) Sou Pes. Weiss. | ara Cele Bie ai erene| f 10) | 16) 4 LOS 10 Mpsey |) 13x) Off Belfast | | oe : | Midn. | NPAs ea Lough. . . | Noone 1a OF peas |; 9 | 1972 | 13:9 2 Ge jeri AS TDs 9-7 V4) Pongo acs 6 | 6 | 144 | 144 Ce RES Nee e | | (8 | W4s4e aor TO! Vous ones LO.) 12°7-|| 1272: 336 THE DEPTHS OF THE SEA. Date and Position. Hour. Temperature of Air. Temperature of Sea-Surface, Date and Position. Hour. Temperature of Air. [CHAP, VIL. Temperature of Sea-Surface. | July 12th | July 13th | At Belfast . July 14th At Belfast July 15th At Belfast July 16th At Belfast SCO b A of CaOrNS — ~ ~— 10 Midn. 2 4 6 8 10 Noon. 2 a ee Ss bo bo tw DO WD bY aT bP ! July 16th | | July 17th | July 18th | July 19th | July 20th | Ati Belfast Off Tuskar L. H. } At Haulbowline 10 Midn. 10 Midn. 2 17°4 16°6 16°6 IEF 18°0 18°3 CHAP. VII. ] DEEP-SEA TEMPERATURES. 337 Date and Position. Hour. Temperature of Air. July 20th . . 8 Tat. 50° 28’ N. j Long. 9° 37’ W. July 2ist. . . 2 10 Lat. 48° BIEN. Long. 11 8 W. July 22nd . . 2 10 Lat. 47°38’ N. } Long. 12° 11' W. § | ~ 4 July 23rd... 2 10 Lat. 47°39’ N. Long. 11° 52’ W. 2 Noon. Noon. Noon. Temperature of Sea-Surface. Date and Position. July 23rd July 24th Lat. 47°40'N. j Long. 11°34 W. § July 25th Lat. 49° 1'N. ) || Long. 12° 22’ W. § July 26th Lat. 49° O'N. Long. 11°58’ W. Hour. 8 10 Midn. Temperature of Air Temperature of Sea-Surface. Deg. Deg. Cent Cent. 17-2 18°3 189 | 183 ilgaais |ralfs gs: lez, 18°3 166 | 18°3 Wea | AES? Tree hers 17°5 186 | 18:0 189 | 183 183 | 183 19°4 | 18°3 189 | 183 SiO leisd SHOT AUS) 18°3 | 18:3 N7Ceh || teks} 17-2 180 169 | 183 NGG al eliza eC) ART LBiOF |) Wa7 189 | 17°7 1823) | aes UScoaa alee ardh ugS¥33. || alyiee 194 | 183 Sima liven 189 | 17°5 161 172 1671 eee, ego | alge 16°71 17°5 1S-9e VW ahe? ISI al) sa be(Sr/ ig} HN Velez 16°9 iid 1G oe living LG | Wied 1671 Wiha L5:8melidad 338 Hour. Date and Position. July 27th Lat. 49°10’ N. Long. 12°45’ W. July 28th 9". 2 10 Lat. 49°59’ N. Long. 12° 22’ W. : July 29th ,. . 2 Lat. 50°24’ N. Long. 11° 42’ W. July 30th \ Noon. Noon. 2 THE DEPTHS OF THE SEA. [CHAP, VIL i) ov 2 oo e. | ge | 2: BH B58 j eI & a 5h Date and Position. E Ae) pag B° | Ba B° | 83 B Een i) ai Deg. Deg Deg. Deg. Cent. Tea Lat, 51° 5 N Cent Cent 155 | 17° at. ; 15:0 | 17:2 |] Long. 11°22’ W. Noon.| 17°7 | 15°8 LOA |) ees 2 ale se7/ 146 Ia: 4 175 16°71 18°9 17°5 6 17:2) | 1636 ; ber 8 16°6 | 16°6 SUS 10 | 166 | 15:5 Wide a eauiiee Midn.| 16°6 | 15°8 18°9 Wey July 3lst. 2 16°3 | 15:5 18°3 lez 4 15°5 15:5 1671 iLSY 6 15 Se ees NGL aed, 8 ye |) ze7 15°8 WT 10 18°9 12°5 15°3 | 17°5 || Near Cork Har- ; ; 150 | 166 || “bour (et. . Neen ee 15°5 169 2 186 | 166 4 18°3 | 1671 ied 656 6 1621) | 15:8 ; f 8 14:4 | 144 NO 6:9 Mids 2a/anlelelei: 183 | 171 || August Ist 2 | 12:2 16°6 16°9 4 12-2 15:5 16°9 6 13°9 15°8 iro 8 16°6 161 | 16°6 10 pis) || ay 161 | 17°2 || At Queenstown. | Noon.| 19°1 | 14°7 15°5 W7/Sz 2 18°9 1%} 15'°8 169 4 2:9) Was 164 | 16:9 6 16°6 16°6 8 1359) | Lows d ‘ 10 12°2 15°0 BAZ Ges Midn.) 12°5 | 14-7 161 | 163 |} August 2nd . 2 | 122 | 144 Iy27/ 16°3 4 11°9 15°0 17°7 | 16°6 6 | 127 | 155. 16S le, 8 15:0 | 15:3 16°1 16°6 10 14:7 16°1 At Queenstown. | Noon CHAP. Vu. ] Hour. Date and Position. August 2nd . August 3rd... 2 Blackwater, Lat. N. 11 miles. Lat. 52° 22’ N. August 4th . . 2 10 At Copeland Is- Noun: andes? «2 2 August 5th .. 2 At Belfast August 6th . Temperature of Air. Temperature of Sea-Surface. DEEP-SEA TEMPERATURES. Date and Position. August 6th . At Belfast August 7th. At Belfast August 8th . At Belfast August 9th . At Belfast Hour. 10 Midn. 10 Midn. 339 Temperature of Air Temperature of Sea-Surface, 3140 THE DEPTHS OF THE SEA. (CHAP. VII. 2 oe 2 2s z zs z as 4 es es A ie a Date and Position, 5 ae oe Date and Position. 3 hs oe = a | a Sc Deg Deg. Deg. Cent. Ceut. Cent. August 10th. 2 | 111 | 139 || August 13th. 2 | 125 4 105 | 14°7 + 127 6 10°55 | 14:4 6 13°3 } 8 | dia | 144 8 | 12-0 10 13°9 10 114 At Belfast Noon.| 15°5 | 15°0 Midn.| 11°1 2 15:0 | August 14th. 2 116 A | Va7 ie 4 | 114 6 IDET | 6 11:4 8 11°9 | 15:0 8 13°3 10 TGS hehe) 10 12°7 Midn.| 11°6 | 13°9 || At Stornoway Noon.| 15°5 August llth, . 2 | 105 | 13°9 2° | GH 4 17 also -t 150 6 1232 | 13i6 6 14-7 8 ieka3_ i) We) 8 13°3 | 10 | 144 10 | 13:3: | In Belfast Lough | Noon.| 14:4 | 14:4 Midn.| 12°7 | 2 | 153 | 122 || August 15th. 2 | 133 4 15:0 | 13°0 4 13°3 6 139) 2 6 | 133 Ss) 12:2) 12:2 8 | _1s9 10 MEZA |) alee 10 139 Midn.} 12°0 | 11°7 || At Stornoway Noon.| 14°4 Angust 12th. . Ze W222 2 | 158 4 VET | ah hey 4 1671 6 11°4 | 12°0 6 15°5 8 13°3 | 12:5 8 13°3 10 172 | 12°7 10 12°7 Yoll Island, N., ) y os Midn.| 13:0 3 miles . . j Nocona) 183) 12 August 16th. 2 lo 2 153 | 13°3 4 EF; at 144 | 12°2 6 13°3 6 DEE | 8 13°3 8 12:2 | 12°0 10 13°6 10 WiE7/ 12°2 Lat. 59° 21’ N. : Midn.| 12:0 | 12-2 || Long. 6° 58’ W. ¢|No™-| 183 August 13th. . 2 NOPE || ALIS ih 2 13°0 4d WR) |) VULNS) | 4 13°3 6 Le e209 | 6 13°3 8 E210) LZ:0N)) 8 12°7 10 14a | WaeG 10 12°5 Shiant Islands, } | ae ; Midn.| 12°2 N.N.W. 6 miles § | NGG) ese eae August 17th. . 277 Nie cup. vu. ] Date and Position. Hour. August 17th. . 4 6 Lat. 59° 36 N. Long. 7° 12’ W. August 18th. . 2 Lat. Long. 60° 25’ N. 8° 9 W. August 19th. Lat. 60° 13'N. )| Long. 6° 41 W. § | | 4 August 20th. . | 2 DELP-SEA TEMPERATURES. 341 Se 7°35 J Sees 9 < as ‘| Date and Position. = | a< Pia ae EG m | gS Ea a | cal | i= Ei Deg Deg. | | Deg | Deg 122 | 119 || Lat. Gur 2578. Seay 122) UNO) Hone Ge Wy ph NOON) ASS" ETS 12:2 1) Qe Moy eels 13°9 | 12:2 A | 122 | 116 : Dn 6 | 94 | 14 es he 8 | O94 | 105 13°6 | 11:9 10 9°7 | 10:0 eS Meee ea, Midn.| 10:0 | 974 130 | 11°9 || August 21st. . 2/100 9°4 12°5 | 11°4 4 94 | 9-4 12-7) Wat 6 | 100 | 9-4 193 ole 8 | 10:0 | 100 12°2 | 10°5 | 10 | 13°6 9°7 12:2) dd 9) Of) Sander iniy) - < 127 |, Vast | Feerve Islands § Noon.| .13°3 a 13-91% | 9 | Wasa S38 136 | 108 | AS Mele ha Oat : ; Got ee 9A 136 | 11:4 | ae aa 127 |, decom 10 | 108 | 94 125, | 10:84 Midn | 105 | 9:4 122 | 11:1 || August 22nd . 9 1105 | 91 Toe Maule 4 |108 | 9:4 Poe iad 6 | tied 9a 12 eit 8 | ir6-| 9:4 122. Nai 9) 10: ieee |e oe 12-2 | 111 || At Thorshavn Noon.| 144 | 94 ey ale 9 A SS | 69:7 ie al a oe 4 | 122 | 100 13:3) || Ta 6 ass 9:7 fe en 8 1105 | 94 re ca Na 10 | 100 | 9-4 POeSy 4 total Midn.| 10°0 | 9:4 139 | Augnst 23rd, 2 9°4 9°4 12°77; | Sue | A 1 e7a ot} ate 6 | 108°] 9-4 127 | lee 8 | 10°5 9°4 122 | 105 | 10 | 197 | 97 12°2 | 10°5 || At Thorshavn Noon.| 12°7 9°7 120 | 10°0 | 2 | 1o-7, 1) 94 12°2 | 10°8 || AL 17 oe 12°5 | 10°5 | 6 |'12De)) 94 12°5 | 103 8: alikee alee Date and Position. August 23rd August 24th. About 10 miles i East of Haalso § August 25th. Lat. 61° 36’ N. Long. 3° 45’ W. August 26th. Lat. 61°14’ N. } Long. 1° 58’ W. § August 27th. THE DEPTHS OF THE SEA. Hour. 10 10 “= 4 6 Midn. Midn. 2 Temperature of Air eS: Temperature ot Sea-Surface. | Date and Position. August 27th. Lat. 60° 26’ N. || Long. 0° 15’ E. August 28th . At Lerwick . August 29th . At Lerwick . | August 30th. At Lerwick . ‘ Hour. 10 Midn. [CHAP, VII. Temperature of Air EE a, ee Oe OOD STIRS (CO CO) 6S OR ST Tt TCO ce tow 0 0 70 SAT AT BB AT ~7 709 1 HD AT a ee ~J ~JI Temperature of Sea-Surface. CHAP. VII. ] Date and Position. Hour. August 30th. August 31st. At Lerwick . September Ist . Lat. 60° 27’ N. Long. 3° 11’ W. September 2nd . Lat. September 3rd . 60° 29’ N. ) | Long. 4°38’ W. § 10 Midn. 10 Midn. | Midn. | 2 .| 114 DEEP-SEA TEMPERATURES. 343 HI 24 22 || Date and Position. 8 =< Ee | FS Bi | BS = Eis i= Deg Deg Deg Dee Cent Cent. Cent Cent ie an Een 44 3. LO AlmlSeOicn EasleG 66 | 111 || Lat. 602 8 N. 2) 72 | 105 || Long. 5° 10’ W. EDS ea | IEE: TSTiae Nei (ORS) 2 125 | Lie6 10°0 NEI 4 TsO seo enlelic6 10:0) |) tiled G yale | Ine 11°6 10°8 8 71-112°5 11-4 12°2 1 LEI 10 WF 116 13:6 |) 11a! Midns; 1277 | 19-2 111 | 11:1 || September 4th . DO e.| Wee? LOS: aint AN (MBS | doo ala: eT 6 13°9 12°5 10°8 10°8 8 13°9 12°5 10°5 1 < 10 14-4 | 129 IEUESH on Lat. 59° 43’ N. , y 11:1 | 11°6 | Long. 6° 35 Wf Noon.| 13°3 | 12°2 116 11°6 2 133 | 1272 SGT WW eISG 4 TSO 22 iti 114 6 QE 2:2. : , 8 LO A EG ce gtr 10 | 122 | 11-6 122 | WEG Midn, | 12°5. | 12:0 13°3 | 11°4 || September 5th . 2) 2-20 | 12-0 TAG ntST 4 1275 IEG 11°4 1S 6 1257) NGG Ta 11°6 8 D237) Si a6 Tei 11°6 10 13°3 12°0 10°38 | 10°8 || Lat. 59°38’ N. : 99 10°38 | 10°5 || Long. 8°25 W. § BRED) SE Ue: 1a 10°3 2 13°6 11°6 sei 10°3 4 TAO SEG ea | 10°3 | Gis | uel 11°6 10: 8 111 11°6 10°0 10 10°8 11°4 1 Ee es esl Gs} Midn.} 11:1 | 11°4 116 | 105 | September 6th . 2 seDis| wake 1 JEG Toei 4 en 114 as: Wa LSIL 6 12°2 11°6 11°6 11°4 8 13°0 N63 aS LEG 10 1257 We 11°6 Taal Tat. 59°37 N. : 96 111 | 111 || Long. 9° awit CE ate Pee anise 2 | 13-0 | 11°6 11°6 4 17 el D2 ODD 344 Date and Position. September 6th . September 7th . Lat. 59° 41’ N. Long. 7° 32' W. September 8th . Lat. 59° 7 N. Long. 6° 35’ W. September 9th . At Stornoway September 10th | THE DEPTHS UF THE SEA. Hour. 8 10 10 Noon. 2 4 6 8 10 Midn. 2 4 Midn. Temperature of Air Temperature of Sea-Surtace. Q ey cot 12°0 12°2 12°2 116 116 116 EY) 116 TLS) 12:2 12°2 12°2 122 12°5 12°2 122 11°6 19 IS 12°2 12°7 12°7 12°7 12°77 . 12°5 125 13°0 13°0 12°7 12°7 Ref 12°7 12°7 12°7 12°7 12°7 12°7 13°3 12°7 17 12°7 03 | In Loch Date and Position. | September 10th At Stornoway September 11th At Stornoway September 12th At Stornoway . September 13th Dany, dae nie = hil Hour. [CHAP. VII. Temperature of Air. 14:4 13°9 Temperature of Sea-Surface 12°2 12:2 CHAP. VII.] Date and Position. Hour. September 13th 8 September 14th 2 Il. Surrace TEMPERATURES Temperature of Air DiLP-SEA Temperature of Sea-Surtace TiMPERATURES. Date and Position Abreast of Mull 345 = ao | &3 ow om B Bee °o Deg. Deg. Cent Cent Noon.| 12°7 | 13°0 2 144 | 13°3 4 AF AS S333 6 SiG; | L2s7 8 TSO} alsa 10 12c5) 4) 1350 Midn.; 12°0 | 13°0 OBSERVED DURING THE SUMMER OF 1870. 5 ES 4 SH | BB Date and Position. 5 as 3a B | ge | Es Deg. Deg Cent, Cent. July 6th . 2 139 es 4 14°4 | 1257 6 13°9 12°5 8 14°7 Ae 7 10 L553" WP 1356 Off Scilly Islands | Noon.| 18°6 | 18°3 2 19°7 | 17°4 4 19°4 | 18°3 6 18°9 | 18°3 8 AE Wh Al7/e7/ 10 16:6 | 17:2 Midn. | 16°1 17°2 July 7th . 2 | 166 | 166 4 166 | 16°6 6 16°6 | 16°6 8 169 | 16°9 7 ; = 10 17°7 | 16°4 at. 48° 49° N. ) : Long. 9° 35’ W. f Noon.| 18°3 | 16°4 2 19°4 | 16°4 4 18°9 | 17:2 | i Date and Position. July 7th . July 8th . Lat. 48°31’ N. Long. 10° 6’ W. July 9th . Hour. Temperature of Air Temperature of Sea-Surface. 346 THE DEPTHS OF THE SEA. [CHAP. VIL. Date and Position. Hour. July 9th. . Lat. 48° 26’ N. Long. 9° 43’ W. July 10th July 11th Lat. 48° 8 N. Long. 9° 18° W. July 12th ,. . Lat. 46° 26’ N. | Long. 9° 31’ W. 10 Midn. 10 Midn. Temperature of Air Temperature of Sea-Surtface. 93 _ eel Qe Date and Position. July 12th July 13th Lat. 44°59’ N. ) Long. 9° 33' W. § July 14th E. N.N. Cape Finisterre, ) 10 miles . July 15th That. (42010 Nt Long. 9°13’ W. 2 es RS = oO ee ee Shee gee H Fric= Deg. Deg. Cent Cent. 6 17:9 | 18:0 8 16°6 | 18°0 10 16°6 | 17:2 Midn.| 16°6 | 17°7 2 Wee | ez 4 y/o} 18:3 6 Weep || azz 8 ISHS |) alz/°5) 10 18:9) led Noon.| 19°7 | 18:2 2 PAA |) aS) 4 22:5 18°9 6 PAIL © || IUs333 8 UpAay. |p sks) 10 Ils) |) ASO) Midn.| 17°2 | 18°0 2 iiz(27/ 17:9 4 WA SA |) 6 169 | 161 8 iss} |) ileal 10 18:6 | Wass Noon.| 18°6 | 15°8 Y 18°6 15°8 4 ISLS |) ists) 6 alfa | TLS 8 1676 || 155 10 16°6 | 158 Midn.| 16°6 | 1671 2 166 | 161 4 16°6 | 16°6 6 Lid || U6 8 18°3 | 16°9 10 18°9 | 17:2 Noon.| 20:0 | 16°4 O22 3a live 4 D2 17°9 6 19°0 189 8 179 | 189 10 ICZAN |jaillS39) PH USD 19°3 CHAP. Vil. ] DEEP-SEA TEMPERATURES. Bu OE ae | ‘ti Boe ecal - Boe ee Date and Position. S Big, a Date and Position, S a! Be AE aes Sane se: & a = Be | Deg. Deg. | Deg. Deg Cent. Cent. || Cent. Cent July 16th 2 | 155 | 190 | July 19th 2 | 203 | 180 4 72 |2118:9 4 20°3 | 18:0 6 16) io 6 19:5 | 17:9 8 | 20°r | 19°4 8 19°4 | 18°3 10 eB) |) 17/9) 10 18°9 | 184 At Vigo . Noon.| 23°6 | 17°8 Midn.| 18°6 | 18°4 2 | 236 | 17-9 || July 20th . . 2 | 4:3) |.18:3 t 23°4 | 18°0 4 18°3 | 183 6 DAG; 8) Ahie 6 19°4 | 18°4 8 18°4 | 1671 | 8 24°4 | 18°9 10 177 | 166%) | 10 23°3 | 20°5 | Midn.| 17°2 | 16:9 -|| Lat. 40° 0’ N. din Bye July 7th . 2, | 77 (“1611 tnete, 9749 Warp on] 244 | AED | a 17°55 | 165 2 \\25sbeale ile | 6 LT, |eliGi6 4 26°3 | 21°8 8 19°7 | 16°4 66 23°3 | 21°8 10 29-2) | V6e 8 216) | 1937 At Vigo...» |Noon.| 32°2 | 16°4 10 | 21:3 | 20°8 2 26°6 | 16°9 Midn.| 21:3 | 20°5 4 | 25°38 | 15°38)! July Qistes . 2 2 | 210i I) 20s 6 22°5 | 16°4 4 21:5 | 19°7 8 20°8 | 16°4 6 23:3 18:9 10 20°0 | 16°5 8 22°7 | 19°4 Midn.| 18°6 | 16°2 7 ni 10 24°5 -| 19°4 Suly 18the . ¢ 2 18°3 | 16°4 ats 39°39" N; ae y A. Nae Long. 9°36’ W. Noon.| 25°5 | 19°4 6 18:9) 16rd 2 | 25:0 | 19°4 8 19°4 | 166 4 | 23°99 | 197 10 18°9 6 21°8 | 19°4 Bat: 41°55 N. : . 8 20°1 | 19°4 Long. 9° 30' W. Noon!) 191) 162 10 | 196 | 19-4 2 186 | 16°3 Midn.| 19°5 | 19°1 4 | 189 | 163 || July22nd:.. . 2 | 19°4 | 189 6 189 | 16°4 4 18°9 | 18:9 8 18°3 | 166 6 20:0 | 18:2 10 18°3 | 16°6 8 212s Sis Midn.| 17°7 | 16°4 10) | 25:0: | 19:4 July 19th 2 |17°7 | 169 || The Farilhoes, are 4 A OW TC 1639 8.S.E. 5 miles Noon: | 200)5) 12.3 6 19°4 | 169 2 23:9 | 19°1 8 20°8 | 17°5 4 23°3 | 20°5 10 201 | ited 6 | 23°9 | 19°4 Lat. 40° 16' N. nee 8 | 20:0 | 19-4 Tiong, 9° a3'tw. | Noon.) 2085) Ere 10 | 189 | 183 318 Date and Position. July 22nd July 23rd At Lisbon July 24th At Lisbon July 25th Lat. 38°10’ N. Long. 9° 29’ W. | July 26th .. THE DEPTHS OF THE SEA. Hour, Temperature of Air [o) oo 503 19°1 18°9 19°3 20°5 23°3 24°7 22°5 23°6 21°6 23°0 20°5 19°5 20°1 19°4 19°4 20°1 20°8 21°2 24°] 23°0 22°1 22°2 20°5 20°0 19°4 19°1 19°0 20°3 20°4 20°8 21°8 21°1 20°8 21°6 20°0 18°6 18:0 18°3 18°3 19°1 19°4 20°3 Temperature of Sea-Surtace. c om i) Cent. aa CON [> i) Date and Position. Hour. [CHAP. VI. Temperature of Air | | | Temperature of Sea-Surface. Tat. 38°17 N Plage Long. 9° 23’ W. { oe July 27th Lat. 37° 18’ N. || Long. 9° 12' W. | July 28th Lat. 36° 55’ N. || Long. 8° 44’ W. July 29th Lat. 36° 45’ N. Long. 8° 8 W. G ef Bo 20°0 20°0 20°0 20°0 19°4 20°0 20°0 19°4 19°4 19°4 20°0 21°3 2171 23°3 21-1 20°0 20°0 19°4 19°5 19°4 19°4 TOR pA ea | 21°1 21°8 21°6 21°6 20°5 18°9 18°9 18°6 18°3 18°3 21°1 22°1 23°0 23°3 23°3 24°8 CHAP. VII. | Date and Position. July 29th July 30th Lat. 36° 27’ N. Long 6° 39 W. July 31st. At Cadiz . August Ist . At Cadiz . August 2nd . DEEP-SEA TEMPERATURES. Hour. 10 Noon. Temperature of Ail Temperature of Sea-Surface. | Co} Ee Eos 349 Lat. 35° 39’ Long. 7° 4’ August 4th . || Lat. 35° 35° N. | Long. 6° 24 W. October Ist . In Strait Gibraltar . =} eS K eS a= Date aud Position. iS 25 Pea a es SS: = Be | Deg Deg. Cent Cent. August 2nd . We Se 2) Bie D359 ls 10 | 22°8 | 94-4 | Lat. 36° 18’ N. : . I eaten Ww | Noon. 22°83 | 23-0 | 2 | 99:5; | 93-0 | A) 227 1230 6 21°8 | 22°8 8 21°2 | 22°2 10 21°3 | 22°5 Midns|) 2s 17229 August 3rd . 2 | 20°5 | 22:0 350 THE DEPTHS OF THE SEA. 2 23 J = £¢ 2 Date and Position. 3S Bo ae Date and Position | = ape Deg. Deg Cent Cent October Ist . 4 | 22°5 | 99:8 || October 5th . - 9 6 22°0 22°6 4 8 Dial: 22°5 6 10 Ales) 92°92 8 Midn.| 20°8 | 22°6 10 October 2nd . 2 | 2171 | 22°8 || Lat. 43° 33’ N. N 4 | 22:3 | 23:3 || Long. 9° 3’ W. oon. 6 22°6 92°9 2) 8 Q4°7 Dey 4 = 10 94°7 23°3 6 at. 36° 27° N. 8 | Long. 8° 31’ W. 4 oO aa eae 10 Ve 22°6 93°4 Midn 4 PBT 23°0 October 6th. . 2 6 20°5 92°5 4 8 20°5 20°5 6 10 20°5 20°8 8 Midn.| 20°5 21°6 10 October 3rd . 2 20:0 | 21°71 || Lat. 46°12’ N. N 4 | 19:4 | 18:3 || Long. 8° 8’ W. oon 6 19°1 20°5 2 8 18°3 20°8 4 - [ 10 18°6 20°5 6 Lat. 38° 39’ N. j , 8 Long. 9° 30 W. {| Noon.) 22°2 | 20°3 10 2g 21°6 20°5 Midn 4 | 21-1 | 21:1 || October 7th . . 2, 6 20°5 20°6 4 8 20°0 19°8 6 10 20°6 2073 8 Midn.| 20°5 20°5 10 October 4th. . 2 20: Sue Lat. 48° 51’ N. N A | 20°6 | 2171 || Long. 5° 54’ W. oom. 6 Oileil: OALIL 2 ' 8 21°6 D5 4 10 22°29, 21°0 6 Lat. 40°57’ N. bg 8 Long. 9° 29’ W. Noon. 922 21°9 10 2 22°9 Heil Midn 4 222, 21°0 October 8th. . 2 6 20°0 20°5 4 8 20°3 90°4 6 10 189 19°4 8 Midn.| 19:3 19°4 10 [CHAP. VII. Temperature of Air, Temperature of Sea-Surface. CHAP. VII. ] DEEP-SEA TEMPERATURES. © oo I oo es AC 3 nad Ese) ARG Date aud Position. Ss ice AS Date and Position. si © = o FS) 2 = ° Deg. Deg Cent. Cent October 8th . English Chan- >| Noon.| 18°6 | 16:2 nel . oa St. Alban’s Hd., ! 9 19°5 | 16:0 || At Cowes Co or — Hour. Midn. Temperature of Air Temperature of Sea-Surface. 352 THE DEPTHS OF THE SEA. [cHAP. VII. APPENDIX. B. Temperature of the Sea at different Depths near the Eastern Margin of the North Atlantic Basin, as ascertained by Serial and by Bottom Soundings. SERIAL SOUNDINGS. Botrom SOUNDINGS. | Tempe- lTempe- |Tempe-| ‘Tempe-/ Tempe- 'Tempe- |'Tempe- Sta- Surface | Bottom Depth | rature.| rature.| rature | rature. ‘ature. | ' rature.| rature.| tion. | Depth.) Tempe- | Tempe- Ser. 23.|Ser. 42. /Ser- 22. Ser. 19.|Ser. 20.,Ser. 21.|Ser 38.| No. rature. | rature. | Deg. | Deg. | Deg. | Deg. | Deg. | Deg. | Deg. | Deg. Deg. | Fms. | Cent. | Cent. | Cent. | Cent. | Cent. | Cent. | Cent. | Fms. Cent. Cent. | 0 | 14:0 O 13°8 | 12°6 | 13°0 | 13:4 | 17°7 oe ee oe os | 50 ao : : ; 34 75 | 18-9 98 | 6 90 12:2 10-0 | 35 | 96| 17-4 | 107 | 100 9-1 | 10°6 8 106 12°3 10-6 24 109 14°3 8-0 | 150 10°5 159 11°8 10:2 14 173 118 9-7 18 183 | 11°8 9-6 200 8°9 | 10:2 13 208 | 12:0 9-7 250 a ao Q-] 89 | 91 9-0 | 10°2 4 fe a aa 300 5 26 4 . 350 9°5 1 370 13:2 9-4 400 6 9-1 | 15 422 ile, 8:3 50 8-6 45 458 15:9 8-9 500 hls ae 81 Sele S35 8&6 8°8 || sy ad oe el 550 axe : E 600 ae 75 4] 584 17°4 8-0 630 ‘ 650 6°8 | 23) | 664 | 1441 53 | 700 6-4 12 | 670| 11:2 | 5:9 | 3 723 125 61 36 | 725| 17-7 | 66 | oes | eek eee ol teal gos | 123 | 5-2 | OU Bes ci ee 2° ; | 16 816 11°6 4°] 862 4°3 | 44 865 | 16:2 4-1 oe ae] ee) PT 98) oe ee 2 ; A 17 1230 11°8 a2 1250 | cs) | sc I) Geo) wo | SD] 18-2) 081 | a9 || 1268! is eee 1300 82 1320 13°3 3°0 1360 3°0 30 | 13880 | 13°3 2°8 1400 1443 |... oe a0 oct 2-7 | | 14760) ese hs tec as ae 27 | 1500 ee Foe con cco cee Su 2-9 ie fy 2°4 | | | s7 | 2435 | 186 | 2:5 CHAP. vit.] DEEP-SEA TEMPERATURES. 393 APPENDIX. C. Comparative Rates of Reduction of Temperature with Increase of Depth at Three Stations in different Latitudes, all of them on the Eastern Margin of the Atlantic Basin. STATION 42. STATION 23. StTaTIOn 87. Lat. 49° 12". Lat. 56° 13°. Lat. 59° 35’. Depth. ————— 2 SSE = = = ; == sar aa Difference. cy as Difference. | pe Difference. Fathous. | Surface.) 17° 0C. 14°01: hee ee 7 AC ALAC. eo VO LOO) i LOG 9:1 8:5 O°: 4 Or Ones 200 iope 8° 9 Si? Ose 5: 0°2 2 300 ONT rocky | OIG O°] | 0:3 409 yal 8°6 Toa 10 10 OD 500 Siow 4,8 isis 0°6 ory 2 600 eee) 6°9 Gx leo 790 ay O83 0:9 767 Dio, as 354 THE DEPTHS OF THE SEA. APPENDIX D. [CHAP. VII. Temperature of the Sea at different Depths in the Warm and Cold Areas lying between the North of Scotland, the Shetland Islands, and the Féroe Islands ; as ascertained by Serial and by Bottom Soundings. N.B.—The Roman numerals indicate the ‘Lightning’ Temperature Soundings, corrected for pressure. | WarRM ARHA, CoLp AREA, (aa ee ee ee eee 3 | | | | ieee Sta- | Surface Bottom pee Ser. 52. Sta- Surface) Bottom ji tion. | Depth.)|Tempe- Tempe- ia e tion: Depth. pa AIDE empe- v | rature. rature, | empe- | Tempe- | No. rature.| rature, Depth. ature, phi ue | Depth. ratace. | fataie, Deg. | Deg. Deg Deg. Deg. | Deg. Deg Fms. | Cent Fms. | Cent. | Cent. || Fms Cent. Cent Fms. | Cent Cent 11-4 | | 0 os |r 50 3-9 73 84 TU bess [p= 48583 50 eo) 9-1 70 66 | 11:9 ts 80 | 92 | 11:8] 9-6 || 69 | 67 | 119| 6% 100 8°5 100 7:2 8:5 68 75 114 6°6 71 103 116 9-2 || 61 114 10°Z te 81 142 11°8 9°5 | 62 125 9°7 7:0 150 8:3 84 | 155 123 9-5 || 150 6:2 8-0 60 | 167 9°77 6°8 85 190 12 9-2 IX. | 170 ileal 5:0 200 8:2 200 4:2 iGo 74 203 11°4 8:7 250 1159, oy 300 8-1 , 300 0-2 —0°7 63 | 317 9-4 | —1:0 65 345 1-1.) =162 76 344 UP |) 1183 50 3855 11°4 7:9 350 | —0°3 54 363 11-4 | —0:3 46 | 374 IARI (OF 384 —0°8 400 Ras | 400 = | 86 | 445 12:0 | —1-1 89 445 IALe7/ 7:5 || 450 —0°8 90 458 U9 to 56 480 11:4) —0:7 49 475 12:0 C4 || 53 490 NIE) |= Li 500 72 500 -1:1 X. 500 KOs yan ee Oy XII. | 530 11°4 hall 58 540 10:8 | —0°7 47 542 ZZ 6°5 || VIII. | 550 Gaps ROVER OO 19 Gl 6°3 550 | 11 77 560 10°5 | —1°3 59 580 11:5 || =1:3 600 | 61 600 SH | XVIE,| 620 111 6:3 || 55 | 605 | 11-4 | —1°3 XIV.) 650 11°6 5°8 57 632 11°1 | —0:8 | 640 —1°4 700 | 88 705 11°9 5:9 || 767 | 52 | } | CHAP, Vu. | DEEP-SEA TEMPERATURES. 300 APPENDIX E. Intermediate Bottom Temperatures, showing the Intermiature of Warm and Cold Currents on the Borders of the Warm and Cold Areas, ] 1 ! | | | | | P | Surface Bottom P Surface | Bottom | | puation. Depth. | Tempera- | Tempera- Station: | Depth. | Tempera- | Tempera- : | ture. GUT Suk rua ture.» | ture! | | : E E Deg. Deg. "Dea Deg. | Fathoms. | Cent. Cent. Fathoms. | Cent Cent. 72 76 11°3 9°3 75 250° | 108 | 55 79 76 Ie, 9°3 ee We PNY) IS | 5°3 73 84 TCS al G:3RR >| Sone eek sete iammiol | | | eee lO 11°6 9:2 83 362 11°8 3°0 | + 74 203 11°4 87 || 66 267 114 Won. ||" 15 440 10°9 B°6 | | CHA PPE, ELE. THE GULF-STREAM. The Range of the ‘Porcupine’ Temperature Observations.—Low Temperatures universal at great Depths.—The Difficulty of in- vestigating Ocean Currents.—The Doctrine of a general Oceanic Circulation advocated by Captain Maury and by Dr. Carpeuter.— ()pinion expressed by Sir John Herschel.—The Origin and Exten- sion of the Gulf-stream.—The Views of Captain Maury; of Pro- fessor Buff ; of Dr. Carpenter.—The Gulf-stream off the Coast of North America.—Professor Bache’s ‘Sections.—The Gulfstream traced by the Surface Temperatures of the North Atlantic —Mr. Findlay’s Views.—Dr. Petermann’s Temperature Charts.—Sources of the underlying Cold Water.—The Arctic Return Currents.— Antarctic Indraught.—Vertical Distribution of Temperature in the North Atlantic Basin. AL the temperature investigations carried on in H.M.SS. ‘ Lightning’ and ‘Porcupine’ during the years 1868-69 and 1870, with the exception of a series of observations already referred to taken in the Mediterranean under Dr. Carpenter’s direction in the summer of 1870, were included within an area nearly 2,000 English miles in length by 250 in width, extending from a little beyond the Féroe Islands, lat. 62° 30’ N., to the Strait of Gibraltar, lat. 36° N. The greater part of this belt may be described as CHAP. VIII. ] THE GULF-STREAM. 357 the eastern Border of the North Atlantic fringing Western Europe. A small but very interesting por- tion of it forms the channel between the Féroe Islands and the North of Scotland, one of the chan- nels of communication between the North Atlantic and the North Sea; and a few soundings in shallow water to the east of Shetland are in the shallow North Sea basin. It is evident, therefore, that the greater part if not the whole of this belt must par- ticipate in the general scheme of distribution of temperature in the North Atlantic, and must owe any peculiarities which its thermal conditions may present to some very general cause. All our temperature observations, except the few taken in the ‘ Lightning’ in 1868, were made with thermometers protected from pressure on Professor Miller’s plan, and the thermometers were individually tested by Captain Davis at pressures rising to about three tons to the square inch before they were fur- nished to the vessel; they were also more than once reduced to the freezing-point during the voyage to ascertain that the glass had been in no way iieiaaee The results may therefore be received with absolute reliance within the limits of error of observation, which were reduced to a minimum by the care of Captain Calver. A large number of scattered observations, most of which have unfortunately been made with instru- ments which cannot thoroughly be depended upon for accuracy of detail,—the error, liowever, being probably in the direction of excess of heat,—esta- blished the singular fact that although the tempera- ture of the surface of the sea in equatorial regions 398 THE DEPTHS OF THE SEA. [CHAP. VIII. may reach 30° C., at the greatest depths both in the Atlantic and in the Pacific the temperature is not higher than from 2° to 4° C., sometimes falling at great depths to 0° C. I quote from Mr. Prestwich’s able presidential address to the Geological Society for the year 1871, a table of the most important of these earlier observations in the Atlantic and the Pacifie :'— TEMPERATURES OF THE ATLANTIC. Temperature. | | : Depth | Latitude. Longitude. in ; Observer and Date. | | Faths. | surface. | Bottom. | 42° o'N. | 34°40’ W.| 780 | 16°7°C.| 6°6°C.| Chevalier . 1837 29 0 3450 | 1400 | 24-4 6'1 ‘ . 1837 7 21 20 40 | 505 | 26°6 2°2 Lenz . . 1832 4 25 26 6 | 1006 | 27°0 3°2 Tessan « SE 15 358. 23 14 | 1200 | 25:0 4°1 “ - 1841 ~| 25 10 7 59 EK. 886 | 19°6 3°0 = . 1841 29 323 10 57 1051 | 1971 2°0 ~ . 1841 32 20 4350 | 1074 | 21°6 2°4 Lenz . . 1832 38 12 54 80 W. | 333 | 168 30 | Tessan - 184i | TEMPERATURES OF THE PACIFIC. | | Temperature. Depth | Latitude. | Longitude. in | Observer and Date. | aoe Surface. Bottom. FiOS Niele 4 Bay 957) | ts8e'Ce |) -95°'Cal essan: , tz | 98 52 Nicer o 600 | 25°5 50 Beechey . . 1828 18 5 | 174 10 ANO | QAe7 4°8 =p «~ ) 836 4 32 134 24W.! 2045 | 97°2 iE, The ‘ Bonite’ 1837 Fquator. | 179 34 1000 | 30°0 2°5 Kotzebue . 1824 21 148. | 196 1 916 | 272 |-. 2e Lenz . - 1834 3 ST | 176 42 E. 782 | 16°4 54 “ > LBS 1066 13°0 ee Tessan . 1841 43 47 | 80 6W. | 1 Address delivered at the Anniversary Meeting of the Geological Society of London on the 17th of February, 1871, by Joseph Prest- wich, F.R.S. Pp. 36, 37, CHAP, VIII.] THE GULF-STREAM. 359 To these may be added the observations of Lieu- tenant 8. P. Lee, of the United States Coast Survey, who, in August 1847, recorded a temperature of 2°°7 C. below the Gulf-stream at a depth of 1,000 fathoms, lat. 35° 26’ N., long. 73° 12) W.; and of Lieutenant Dayman, who found the temperature at 1,000 fathoms in lat. 51° N. and long. 40° W. to be —0°4C., the surface temperature being 12°5 C. These results are fully borne out by the recent determinations of Captain Shortland, R.N., who observed a temperature of 2°5 C. in deep water in the Arabian Sea between Aden and Bombay,’ by those of Commander Chimmo, R.N., and Lieutenant Johnson, R.N., who found at various points in the Atlantic a temperature of about 3°9 C. at 1,000 fathoms, and a slow decrease from that point to 2,270 fathoms, where the temperature registered by unprotected thermometers was 6°6 C. reduced by the necessary correction for pressure to about 1°6 C., and finally by the temperature determinations of the ‘Porcupine’ expeditions, carefully conducted with protected instruments, but not carried nearer the tropics than the latitude of the Strait of Gibraltar ; and they appear to go far to establish a nearly uni- form temperature for abyssal depths, not far from the freezing-point of fresh water. As it was evident that the low temperature for deep water in tropical regions could not be acquired ? Sounding Voyage of H.M.S. ‘Hydra,’ Captain P. F. Shortland. London : 1869. * Soundings and Temperatures in the Gulf-stream. By Commander W. Chimmo, R.N. (Proceedings of the Royal Geographical Society, vol. xiii.) 360 THE DEPTHS OF THE SEA. [CHAP. VI11. by contact with the surface of the crust of the earth, the inevitable conclusion seems to have been early arrived at that, if such temperatures existed, they must be due to a general oceanic circulation,— to surface currents of warm water passing towards the poles, and compensating counter-currents of cold water from the poles towards the equator. Hum- boldt states that he showed, in 1812, “that the low temperature of the tropical seas at great depths could only be owing to currents from the poles to the equator.” ! D’Aubuisson, in 1819, also attributed the low temperature of the sea at great depths at or near the equator to the flow of currents from tie poles.’ But although the fact of the existence of currents lowering the temperature of deep water in equa- torial regions was admitted by various authorities in physical geography, little light was thrown upon the causes of this circulation. Latterly, the whole subject became obscured by the very general adop- tion of the doctrine already referred to of a perma- nent temperature of 4° C. all over the world beyond a certain depth; and it was not until the publi- cation of Captain Maury’s fascinating book on the ‘Physical Geography of the Sea’ had given an extra- ordinary stimulus to the study of this department of science, that the question was again raised. It was natural from its geographical position, and from the much greater opportunity which it offered for the accumulation of the almost infinite number 1 Fragments de Géol. et de Climatol. Asiat., 1831. Geological Society of London, 1571, ee CHAP. VIII. ] THE GULF-STREAM. 361 of data required for the consideration of such sub- jects, that the basin of the North Atlantic should be selected for investigation, more particularly as peculiarities of climate seemed there to be limited in space, and well defined and even extreme in character. It seems at first somewhat singular that there should be any room for question as to the causes, the sources, and the directions of the ocean currents which traverse the ocean in our immediate neigh- bourhood, and exercise a most important influence on our economy and well-being. ‘The investigation is, however, one of singular difficulty. Some currents are palpable enough, going at a rate and with a force which make it easy to detect them, and even com- paratively easy to gauge their volume and define their path; but it seems that the great movements of the water of the ocean, those which produce the most important results in the transfer of tempera- ture and the modification of climate, are not of this character. ‘These move so slowly that their surface movement is constantly masked by the drift of vari- able winds, and they thus produce no sensible effect upon navigation. The path and limits of such bodies of moving water can only be determined by the use of the thermometer. ‘The equalizing of the temperature of bodies of water in contact with one another and differently heated, by conduction, diffusion, and mixture, is however so slow, that we usually have but little difficulty in distinguishing currents from different sources. Up to the present time little had been done in determining the depth and mass of currents by the 862 THE DEPTHS OF THE SEA. [CHAP, VIIL. thermometer, and under-currents were practically unknown; but the limits of surface currents had been traced with considerable precision by observa- tions of the temperature of the surface of the sea, even when the movement was so slow as not to be otherwise perceptible. The amount of heat received directly from the sun may be taken approximately to depend upon latitude only, and this heat is in addition to the heat of the surface water derived from other sources, whatever these may be. Observa- tions of surface temperature accordingly give us the heat derived directly from the sun in the region, and the heat derived from the same source during the passage of the water to the region, in addition to the original heat of the water; if, therefore, the water of any region be derived from—that is to say, form part of—a movement of water from a polar source, and if the surface water of another area on the same parallel of latitude form part of an equatorial current, although in that particular latitude they receive in both cases the same amount of heat from the sun, there will be a marked difference in their tempera- ture. To take an extreme case; the mean tem- perature of the sea in the month of July off the Hebrides, in lat. 58° N., in the path of the Gulf- stream, is 13° C.; while in the same latitude off the coast of Labrador, in the course of the Labrador current, it is 4°°5 C, The distribution of surface temperature in the North Atlantic is certainly very exceptional. C:, while, that of Dublin, lat. 53°21" N., is 9°6C.; and the temperature of Boston (Mass.), Jat. 42° 21’ N., is exactly the same as that of Dublin. 564 THE DEPTHS OF THE SEA. [cHAP. VI, This remarkable diversion of the isothermal lines from their normal direction is admittedly caused by ocean currents affecting the temperature of the surface while conveying the warm tropical water towards the polar regions, whence there is a con- stant counterflow of cold water beneath to supply its place. We thus arrive at the well-known result that the temperature of the sea bathing the north-eastern shores of the North Atlantic is raised greatly above its normal point by currents involving an infer- change of tropical and polar water; and that the lands bordering on the North Atlantic participate in this amelioration of climate by the heat imparted by the water to their prevailing winds. This phenomenon is not confined to the North Atlantic, although from its peculiar configuration and relation to the land that ocean presents the most marked example. CHAP. VIII. ] _ THE GULF-STREAM. 40] expected if the Gulf-stream came close to the western shore. While the communication between the North Atlantic, and the Arctic Sea—itself a second cul de sac—is thus restricted, limiting the interchange of warm and cold water in the normal direction of the flow of the Gulf-stream, and causing the diversion of a large part of the stream to the southwards, the communication with the Antarctic basin is as open as the day ;—a continuous and wide valley upwards of 2,000 fathoms in depth stretching northwards along the western coasts of Africa and Europe. That the southern water wells up into this valley there could be little doubt from the form of the eround; but here again we have curious corroborative evidence on the map in the remarkable reversal of the curves of the isotherms. The temperature of the bot- tom water at 1,230 fathoms off Rockall is 3°22 C., exactly the same as that of water at the same depth in the serial sounding, lat. 47° 38’ N., long. 12° 08° W. in the Bay of Biscay, which affords a strong presumption that the water in both cases is derived from the same source; and the bottom water off Rockall is warmer than the bottom water in the Bay of Biscay (2°5 C.), while a cordon of temperature soundings drawn from the north-west of Scotland to a point on the Iceland shallow gives no temperature lower than 6°5 C. This makes it very improbable that the low temperature of the Bay of Biscay is due to any considerable por- tion of the Spitzbergen current passing down the west coast of Scotland; and as the cold current to the east of Iceland passes southwards considerably to the westward, as indicated on the map by the successive DD 402 THE DEPTHS OF THE SEA. (CHAP. VI. depressions in the surface isotherms, the balance of probability seems to be in favour of the view that the conditions of temperature and the slow movement of this vast mass of moderately cold water, nearly two statute miles in depth, are to be referred to an Antarctic rather than to an Arctic origin. The North Atlantic Ocean seems to consist first of a great sheet of warm water, the general northerly reflux of the equatorial current. Of this the greater part passes through the Strait of Florida, and its north-easterly flow is aided and maintained by the anti-trades, the whole being generally called the Gulf-stream. This layer is of varying depths, ap- parently from the observations of Captain Chimmo and others, thinning to a hundred fathoms or so in the mid-Atlantic, but attaining a depth of 700 to 800 fathoms off the west coasts of Ireland and Spain. Secondly of a ‘stratum of intermixture’ which ex- tends to about 200 fathoms in the Bay of Biscay, through which the temperature falls rather rapidly ; and thirdly, of an underlying mass of cold water, in the Bay of Biscay 1,500 fathoms deep, derived as an indraught falling in by gravitation from the deepest available source, whether Arctic or Antarctic. It seems at first sight a_ startling suggestion, that the cold water fillmg deep ocean valleys in the northern hemisphere may be partly derived from the southern; but this difficulty, I believe, arises from the idea that there is a kind of diaphragm at the equator between the northern and southern ocean basins, one of the many misconceptions which follow in the train of a notion of a convective circulation in the sea similar to that in the atmosphere. There is CHAP. VIII. ] THE GULF-STREAM. 403 undoubtedly a gradual elevation of an intertropical belt of the underlying cold water, which is being raised by the subsiding of still colder water into its bed to supply the place of the water removed by the equatorial current and by excessive evaporation ; but such a movement must be widely and irregularly diffused and excessively slow, not in any sense com- parable with the diaphragm produced in the atmo- sphere by the rushing upwards of the north-east and south-east trade-winds in the zone of calms. Perhaps one of the most conclusive proofs of the extreme slowness of the movement of the deep indraught is the nature of the bottom. Over a great part of the floor of the Atlantic a deposit is being formed of microscopic shells. These with their living inha- bitants differ little in specific weight from the water itself, and form a creamy flocculent layer, which must be at once removed wherever there is a perceptible movement. In water of moderate depth, in the course of any of the currents, this deposit is entirely absent, and is replaced by coarser or finer gravel. It is only on the surface of the sea that a line is drawn between the two hemispheres by the equatorial current, whose effect in shedding a vast intertropteal drift of water on either side as it breaks against the eastern shores of equatorial land may be seen at a glance on the most elementary physical chart. The Gulf-stream loses an enormous amount of heat in its northern tour. Ata point 200 miles west of Ushant, where observations at the greatest depths were made on board the ‘ Porcupine,’ a section of the water of the Atlantic shows three surfaces at which interchange of temperature is taking place. Di DZ 404 THE DEPTHS OF THE SEA. [CHAP. VILL First, the surface of the sea—that is to say, the upper surface of the Gulf-stream layer—is losing heat rapidly by radiation, by contact with a layer of air which is in constant motion and being per- petually cooled by convection, and by the con- version of water into vapour.’ As this cooling of the Gulf-stream layer takes place principally at the surface, the temperature of the mass is kept pretty uniform by convection. Secondly, the band of con- tact of the lower surface of the Gulf-stream water with the upper surface of the cold indraught. Here the interchange of temperature must be very slow, though that it does take place is shown by the slight depression of the surface isotherms over the principal paths of the indraught. But there is a good deal of intermixture extending through a con- siderable layer. The cold water being beneath, convection in the ordinary sense cannot occur, and interchange of temperature must depend mainly upon conduction and diffusion, causes which in the case of masses of water must be almost secular in their action, and probably to a much greater extent upon mixture produced by local currents and by the tides. The third surface is that of contact be- tween the cold indraught and the bottom of the sea. The temperature of the crust of the earth has been variously calculated at from 4° to 11°C., but it must be completely cooled down by anything like a movement and constant renewal of cold water. * On Deep-sea Climates. The Substance of a Lecture delivered to the Natural Science Class in Queen’s College, Belfast, at the close of the Summer Session 1870, by Professor Wyville Thomson. (ature, July 28th, 1870.) CHAP. VIII. ] THE GULF-STREAM. 405 All we can say, therefore, is that contact with the bottom can never be a source of depression of tem- perature. As a general result the Gulf-stream water is nearly uniform in temperature throughout the - greater part of its depth; there is a marked zone of intermixture at the junction between the warm water and the cold, and the water of the cold indraught is regularly stratified by gravitation ; so that in deep water the contour lines of the sea-bottom are, speaking generally, lines of equal temperature. Keeping in view the enormous in- fluence which ocean currents exercise in the dis- tribution of climates at the present time, I think it is scarcely going too far to suppose that such currents—movements communicated to the water by constant winds—existed at all geological periods as the great means, I had almost said the sole means, of producing a general oceanic circulation, and thus distributing heat in the ocean. They must have existed, in fact, wherever equatorial land inter- rupted the path of the drift of the trade-winds. Wherever a warm current was deflected to north or south from the equatorial belt a polar indraught crept in beneath to supply its place; and the ocean consequently consisted, as in the Atlantic and doubtless in the Pacific at the present day, of an upper warm stratum, and a lower layer of cold water becoming gradually colder with increasing depth. I fear, then, that in opposition to the views of my distinguished colleague, I must repeat that I have seen as yet no reason to modify the opinion which I have consistently held from the first, that 406 THE DEPTHS OF THE SEA. [CHAP, VIII. the remarkable conditions of climate on the coasts of Northern Europe are due in a broad sense solely to the Gulf-stream. That is to say, that although movements, some of them possibly of considerable importance, must be produced by differences of spe- cific gravity, yet the influence of the great current which we eall the Gulf-stream, the reflux of the ereat equatorial current, is so paramount as to reduce all other causes to utter insignificance. THE GIANT AND THE HAG. CHAPTER IX. THE DEEP-SEA FAUNA. The Protozoa of the Deep-sea.—Bathybius.—‘ Coccoliths,’ and ‘ Cocco- spheres.’—The Foraminifera of the Warm and Cold Areas.—Deep- sea Sponges. —The Hexactinellidee. — Rossella,.— Hyalonema.— Deep-sea Corals.—The Stalked Crinoids.—Pentacrinus.—Rhizo- crinus. — Bathycrinus.—The Star-fishes of the Deep-sea.—The general Distribution and Relations of Deep-sea Urchins.—The Crustacea, the Mollusca, and the Fishes of the ‘ Porcupine’ Expe- ditions. THe time has not yet arrived for giving anything like a detailed account of the deep-sea fauna; even if it were possible to do so in a popular sketch of the general results of a wide investigation. I must therefore confine myself at present to a brief outline of the distribution of the forms of animal life which were met with in the belt partially examined during the ‘Porcupine’ dredgings, a belt which carries the British zoological area about a hundred miles further out to seaward along the northern and western coasts of the British Isles, and into depths extending from 200 fathoms, the previous limit of accurate know- ledge, to 800 and 1,000 fathoms, and in one or two instances to the extreme depth of upwards of 2,000 fathoms. 408 THE DEPTHS OF THE SEA. [CHAP. 1X. The remarkable general result that even to these ereat depths the fauna is varied and rich in all the marine invertebrate groups, has inundated us with new material which in several of the larger depart- ments it will take years of the labour of specialists to work up. While referring very briefly to those orders which it has been found impossible as yet to overtake, I will enter a little more fully into the history of certain restricted groups which more par- ticularly illustrate the conditions of the abyssal region, and the relations of its special fauna to the faunze of other zoological provinces, or to those of earlier times. And very prominent among these special groups we find the first and simplest of the invertebrate sub-kingdoms, the Protozoa, represented by three of its classes,—the monera, the rhizopoda, and the sponges. The monera have been lately defined as a distinct class by Professor Ernst Haeckel,! for a vast assem- blage of almost formless beings, apparently abso- lutely devoid of internal structure, and consisting simply of living and moving expansions of jelly-like protoplasm ; and although the special character on which Haeckel separates them from the remainder of the protozoa,—that they are propagated by no form of sexual reproduction, but simply by spontaneous division,—may probably prove deceptive as our know- ledge increases, still their number, their general resemblance to one another, presenting obviously different and recognizable kinds although with very indefinable characters, and the important part which * Biologische Studien. Von Dr. Ernst Haeckel, Professor an der Universitat Jena. Leipzig, 1870. CHAP, IX. | THE DEEP-SEA FAUNA. 409 they play in the economy of nature, would seem to entitle them to a systematic position of more than ordinal value. The German naturalists of the new school, in their enthusiastic adoption of the Dar- winian theory of evolution, naturally welcome in these ‘moners’ the essential attribute of the ‘ Ur- sehleim,’ an infinite capacity for improvement in every conceivable direction; and to more prosaic physiologists they are of the deepest interest, as presenting the essential phenomena of life, nutri- tion and irritability, existing apparently simply as the properties of a homopencous chemical compound, and independent of organization. The monera pass into the rhizopoda, which give a slight indication of advance, in the definite form of the graceful calcareous shell-like structures which most of them secrete, and the poe groups may be taken together. The dredging at 2,435 fathoms at the mouth of the Bay of Biscay gave a very fair idea of the con- dition of the bottom of the sea over an enormous area, as we know from many observations which have now been made, with the various sounding instruments contrived to bring up a sample of the bottom. On that occasion the dredge brought up about 13 ewt. of calcareous mud. There could be little doubt, from the appearance of the contents of the dredge, that the heavy dredge-frame had gone down with a plunge, and partly buried itself in the soft, yielding bottom. ‘The throat of the dredge thus became partly choked, and the free entrance of the organisms on the sea-floor had been thus prevented. The matter contained in the dredge con- 410 THE DEPTHS OF THE SEA. [CHAP. IX. sisted mainly of a compact ‘mortar,’ of a bluish colour, passing into a thin—evidently superficial— layer, much softer and more creamy in consistence, and of a yellowish colour. Under the microscope the surface-layer was found to consist chiefly of entire shells of Globigerina bulloides (Fig. 2, p. 22), large and small, and fragments of such shells mixed with a quantity of amorphous calcareous matter in fine particles, a little fine sand, and many spicules, portions of spicules, and shells of Radiolaria, a few spicules of sponges, and a few frustules of diatoms. Below the surface-layer the sediment becomes eradually more compact, and a slight grey colour, due probably to the decomposing organic matter, becomes more pronounced, while perfect shells of elobigerina almost entirely disappear, fragments be- come smaller, and caleareous mud, structureless and in a fine state of division, is in greatly preponderat- ing proportion. One can have no doubt, on examining this sediment, that it is formed in the main by the accumulation and disintegration of the shells of — elobigerina—the shells fresh, whole, and living in the surface-layer of the deposit, and in the lower layers dead, and gradually crumbling down by the decomposition of their organic cement, and by the pressure of the layers above—an animal formation in fact being formed very much in the same way as in the accumulation of vegetable matter in a peat bog, by life and growth above, and death, retarded de- composition, and compression beneath. In this dredging, as in most others in the bed of the Atlantic, there was evidence of a considerable quantity of soft gelatinous organic matter, enough CHAP. 1X] THE DEEP-SEA FAUNA. en to give a slight viscosity'to the mud of the surface layer. If the mud be shaken with weak spirit of wine, fine flakes separate like coagulated mucus ; and if a little of the mud im which this viscid con- dition is most marked be placed in a drop of sea- water under the microscope, we can usually see, after a time, an irregular network of matter resem- bling white of egg, distinguishable by its maintaining its outline and not mixing with the water. This network may be seen gradually altering in form, and entangled granules and foreign bodies change their relative positions. ‘The gelatinous matter is therefore capable of a certain amount of movement, and there can be no doubt that it manifests the phenomena of a very simple form of life. To this organism, if a being can be so called which shows no trace of differentiation of organs, consist- ing apparently of an amorphous sheet of a protein compound, irritable to a low degree and capable of assimilating food, Professor Huxley has given the name of Bathybius haeckelii (Fig. 63). If this have a claim to be recognized as a distinct living entity, ex- hibiting its mature and final form, it must be referred to the simplest division of the shell-less rhizopoda, or if we adopt the class proposed by Professor Haeckel, to the monera, The circumstance which gives its special interest to Bathybius is its enormous extent : whether it be continuous in one vast sheet, or broken up into circumscribed individual particles, it appears to extend over a large part of the bed of the ocean ; and as no living thing, however slowly it may live, is ever perfectly at rest, but is continually acting and reacting with its surroundings, the bottom of the AT THE DEPTHS OF THE SEA. (CHAP. 1X. sea becomes like the surface of the sea and of the land,—a theatre of change, performing its part in maintaining the ‘ balance of organic nature.’ Fic. 63.—‘‘ Eine grossere Cytode von Bathybius mit eingebetteten Coccolithen. Das Proto- plasma, welches viele Discolithen und Cyatholithen enthalt, bildet ein Netzwerk mit breiten trangen.” (x. 700.) 1 ‘ Biologische Studien. Von Dr. Ernst Haeckel, Professor an der Universitat Jena. Leipzig, 1870. CHAP. 1x.] THE DEEP-SEA FAUNA. 413 Entangled and borne along in the viscid streams of Bathybius, we so constantly find a multitude of minute calcareous bodies of a peculiar shape, that the two were for long supposed to have some mutual relation to one another. These small bodies, which have been carefully studied by Huxley,’ Sorby,’ Haeckel,’ Carter,* Giimbel,’ and others, are in shape somewhat like oval shirt-studs. There is first a little oval disk about 0°01 mm. in length, with an oblong rudely facetted elevation in the centre, and round that, in fresh specimens, what seems to be a kind of frill of organic matter, then a short neck, and lastly a second smaller flat disk, like the disk at the back of a stud. ‘To these bodies, which are met with in all stages of development, Professor Huxley has given the name of ‘ coccoliths.’ Some- times they are found aggregated on the surface of small transparent membranous balls, and these which seemed at first to have something to do with the production of the ‘coccoliths’ Dr. Wallich has called ‘coccospheres’ (Fig. 64). Professor Ernst Haeckel has lately described a very elegant organ- ism belonging to the radiolaria and apparently allied to Thalassicolla,—Myxobrachia rhopalum,—and at the ends of some curious diverging appendages of this creature he has detected accumulations of bodies closely resembling, if not identical with, the coccoliths and coccospheres of the sea-bottom. These * Quarterly Journal of Microscopical Science, 1868, p. 203. 2 Proceedings of the Sheffield Literary and Philosophical Society, October 1860. 3" Op. eit. 4 Ann. and Mag. Nat. Hist. 1871, p. 184. 5 Jahrbuch Miinch. 1870, p. 753. A414 THE DEPTHS OF THE SEA. [CHAP, 1X. bodies seem to have been taken in to the JMyxro- brachia as food, the hard parts accumulating in cavities in the animal’s body after all the available nourishment had been absorbed. It is undoubted that a large number of the organisms whose skele- tons are mixed with the ooze of the bottom of the sea live on the surface, the delicate silicious or eal- sareous Shields or spines falling gradually through Fia. 64.—‘ Coecosphere.’ (x. 1000.) the water and finally reaching the bottom, what- ever be the depth. I think that now the balance of opinion is in favour of the view that the coccoliths are joints of a minute unicellular alga living on the sea-surface and sinking down and mixing with the sarcode of Bathybius, very probably taken into it with a purpose, for the sake of the vegetable matter they may contain, and which may afford food for the animal jelly. What the coccospheres are, and CHAP. IX] THE DEEP-SEA FAUNA. 415 what relation, if any, they have to the coccoliths, we do not know. Living upon and among this Bathybius, we find a multitude of other protozoa,--foraminifera and other rhizopods, radiolarians, and sponges; and we as yet know very little of the life-history of these eroups. ‘There can be no doubt that when their development has been fully traced many of them will be found to be di- or poly-morphic, and that when we are acquainted with their mode of multi- plication we shall meet with many cases of pleo- morphism and wide differences between the organs and products involved in propagation and in repro- duction. I feel by no means satisfied that Bathybius is the permanent form of any distinct living being. It has seemed to me that different samples have been different in appearance and consistence; and although there is nothing at all improbable in the abundance of a very simple shell-less ‘moner’ at the bottom of the sea, I think it not impossible that a great deal of the ‘bathybius,’ that is to say the diffused formless protoplasm which we find at great depths, may be a kind of mycelium—a formless condition connected either with the growth and multiplication or with the decay—of many different things. Many foraminifera of different groups inhabit the deep water, lying upon or mixed in the upper layer of the globigerina ooze, or fixed to some foreign body, such as a sponge, coral, or stone; and all of these are remarkable for their large size. In the ‘warm area,’ and wherever the bottom is covered with ooze, calcareous forms predominate, and large sandy eristellarians, with their sand-grains bound together 416 THE DEPTHS OF THE SEA. [CHAP. IX, by calcareous cement, so that the sand-grains show out, dark and conspicuous, scattered on the surface of the white shell. Miliolines are abundant, and the specimens of Cornuspira and Biloculina are greatly larger than anything which has been hitherto met with in temperate regions, recalling the tropical forms which abound among the Pacific Islands. In the cold area, and in the paths of cold currents, foraminifera with sandy tests are more numerous; some of those of the genera =i 2 ae Fxroe Channel. Twice the natural size. Fitroe Channel. I have already referred to as being found on the coasts of Portugal and of Japan. It is a common fossil in the coralline crag of Calabria. The mol- lusea which are of the most special interest, how- ever, are those which we must refer to the abyssal fauna. About this group we know as yet very little. Like the Echinoderms, they seem to be special, and to have a wide lateral extension. Pleuronectia lucida, JEFFREYS (Fig. 78), a pretty little clam be- longing to the Pecten pleuronectes set, is figured both from the North Atlantic and from the Gulf of CHAP. IX. ] THE DEEP-SEA FAUNA. 465 Mexico. The abyssal mollusca are by no means de- void of colour, though, as a rule, they are paler than those from shallow water. Daecrydium vitreum— a curious little mytiloid shell-fish which makes and inhabits a delicate flask-shaped tube of foraminifera, Fic. 78.—Pleuronectia lucida, JEFFREYS. Twice the natural size. a, from the Eastern Atlantic b, from the Gulf of Mexico. sponge spicules, coccoliths, and other foreign bodies, cemented together by organic matter and lined by a delicate membrane—is of a fine reddish brown colour dashed with green, from 2,435 fathoms; and the Fie. 79.—Pecten hoskynsi, FoRBes. Twice the natural size. ynst, animals of one or two species of Zima from extreme depths are of the usual vivid orange scarlet.. Neither are the abyssal mollusca universally destitute of eyes. A new species of Plewroloma from 2,090 fathoms had a pair of well-developed eyes on short footstalks; and tie 466 THE DEPTHS OF THE SHA. [CHAP. 1X. a Fusus from 1,207 fathoms was similarly provided. The presence of organs of sight at these great depths leaves little room to doubt that hght must reach even these abysses from some source. From many con- siderations it can scarcely be sun-light. I have already thrown out the suggestion that the whole of the light beyond a certain depth might be due to phosphorescence, which is certainly very general, particularly among the larve and young of deep- sea animals; but the question is one of extreme interest and difficulty, and will require careful in- vestigation. BORDO, KUNO, AND KALSO, FROM THE HAMLET OF VIDERO. CHAPTER X. THE CONTINUITY OF THE CHALK. Points of Resemblance between the Atlantic Ooze and the White Chalk.—Differences between them.—Composition of Chalk.—The Doctrine of the Continuity of the Chalk.— Objections. —Arguments in favour of the View from Physical Geology and Geography.— Former Distribution of Sea and Land.—Palontological Evidence. —Chalk-flints—Modern Sponges, and Ventriculites.~—Corals.— Echinoderms.— Mollusca. —Opinions of Professor Huxley and Mr. Prestwich.—The Composition of Sea-water. Matter.—Analysis of the contained Gases.— Differences of Specific Gravity.—Conclusion. Presence of Organic Apprenpix A,—Summary of the Results of the Examination of Samples of Sea-water taken at the Surface and at various Depths. By William Lant Carpenter, B.A., B.Sc. APPENDIX B.—Results of the Analyses of Eight Samples of Sea-water collected during the Third Cruise of the ‘Porcupine.’ By Dr. Frankland, F.R.S. Apprenbix C.—Notes on Specimens of the Bottom collected during the First Cruise of the ‘Porcupine’ in 1869. By David Forbes, FE.R.S. Appenpix D.—Note on the Carbonic Acid contained in Sea-water. By John Young Buchanan, M.A., Chemist to the ‘Challenger’ Expedition. Very speedily after the first samples of the bottom of the mid-Atlantic had been brought up by the sound- ing-line, and submittel to chemical analysis and HH 2 468 THE DEPTHS OF THE SEA. [cHap. x, to microscopical examination, many observers were struck with the great similarity between its compo- sition and structure and that of the ancient chalk. I have already described the general character and the mode of origin of the great calcareous deposit which seems to occupy the greater part of the bed of the Atlantic. If we take a piece of the ordinary soft white chalk of the south of England, wash it down with a brush in water, and place a drop of the milky product on the slide of a microscope, we find that it consists, like the Atlantic ooze, of a large pro- portion of fine amorphous particles of lime, with here and there a portion of a Globigerina shell, and more rarely one of these shells entire, and a considerable proportion—in some examples coming up to nearly one-tenth of the whole—of ‘ coccoliths,’ which are indistinguishable from those of the ooze. Altogether two slides—one of washed down white chalk, and the other of Atlantic ooze—resemble one another so clearly, that it is not always easy for even an accom- plished microscopist to distinguish them. The nature of chalk can also be well shown, as has been done by Ehrenberg and Sorby, by cutting it into thin dia- phanous slices, when the mode of aggregation of the different materials can be readily demonstrated. But while successive observers have brought out more and more clearly those resemblances,—suffi- ciently striking to place it beyond a doubt that the chalk of the cretaceous period and the chalk-mud of the modern Atlantic are substantially the same,—a more careful investigation shows that there are very important differences between them. The white chalk is very homogeneous, more so perhaps than any other CHAP. X.] CONTINUITY OF THE CHALK. 469 sedimentary rock, and may be said to be almost pure carbonate of lime. I quote an analysis of the white chalk of Shoreham (Sussex), by Mr. David Forbes.' Calciumicarbonate. 2) 4... 2. . 98:40 Magnesium carbonate - . . °. . = - 0:08 Insolublefrock.débris 2. 2 1:10 /ANOMIMNITE, MMACLNOSS “4 5 5 6 4 6 o 0:42 100-00 Even the grey chalk of Folkestone contains a very large proportion of carbonate of lime, the other substances existing merely as impurities which can scarcely be said to enter into the composition of the rock. The following is an analysis by Mr. Forbes of the base of the Folkestone grey chalk :— Caleiumycarbonate ire. “2905s ee 78 oe E09 Magnesium carbonate . .-. . . . . Odi Imsolubblevnockedebris tu” 2 ye ese a fen) -osOd Phosphoric acid iumamasamagslosse 00. ts se ee eee nt | PIES Pomimmachlormaece ex cele ae ey Uae ee IEZS Mice anss (ae etet eee ae hab Og Q 100-00 The most remarkable point in this analysis is that while white chalk is almost always associated with chert and flints, the chalk itself does not contain a particle of silica. The chalk-mud of the Atlantic on the other hand contains not more than 60 per cent. of calcium car- bonate, with 20 to 30 per cent. of silica, and varying proportions of alumina, magnesia, and oxide of iron. We must remember, however, that in the English 1 Quoted in Mr. Prestwich’s Presidential Address, 1871. an +e 470 THE DEPTHS OF THE SEA. [CHAP., X. cliffs we have the chalk in its very purest form, and that in various parts of the world it assumes a very different character, and contains carbonate of lime in very different proportions. Mr. Prestwich instances a bed 28 to 30 feet thick of the white chalk (Terrain Senonien) of Touraine, in which carbonate of lime is entirely absent. There can be no doubt whatever that we have forming at the bottom of the present ocean, a vast sheet of rock which very closely resembles chalk ; and there can be as little doubt that the old chalk, the cretaceous formation which in some parts of Eng- land has been subjected to enormous denudation, and which is overlaid by the beds of the tertiary series, was produced in the same manner, and under closely similar circumstances ; and not the chalk only, but most probably all the great limestone formations. In almost all of these the remains of foraminifera are abundant, some of them apparently specifically iden- tical with living forms; and in a large number of limestones of all ages Dr. Giimbel has detected the characteristic ‘ coccoliths.’ Long before commencing the present investigation, certain considerations had led me to regard it as highly probable that in the deeper parts of the At- lantic a deposit, differing possibly from time to time in composition but always of the same general cha- racter, might have been accumulating continuously from the cretaceous or even earlier periods to the present day. This view I suggested in my first letter to Dr. Carpenter urging the exploration of the sea- bed; and from the first it has had the cordial support of my colleague, whose intimate acquaintance with CHAP X.] CONTINUITY OF THE CHALK. 47] some of the animal groups whose remains enter most largely into the chalk both old and new, makes his opinion on such a subject particularly valuable. On our return from the ‘ Lightning’ cruise, during which we believed that our speculation had received strong confirmation, we used the expression,—perhaps somewhat an unfortunate one since it was capable of misconstruction,—that we might be regarded in a certain sense as still living in the cretaceous period. Several very eminent geologists, among whom were Sir Roderick Murchison and Sir Charles Lyell, took exception to this statement; but it seems that their censure was directed less against the opinion than the mode in which it was expressed; and I think I may say that the doctrine of the continuity of the chalk, in the sense in which we understood it, is now very generally accepted. I do not maintain that the phrase ‘ we are still living in the cretaceous epoch,’ is defensible in a strictly scientific sense, chiefly because the terms ‘geological epoch’ and ‘geological period’ are thoroughly indefinite. We speak indifferently of the ‘ Silurian period,’ and the ‘ Glacial period,’ with- out consideration of their totally unequal value ; and of the ‘Tertiary period,’ and of the ‘ Miocene period,’ although the one includes the other. The expression is intended rather in a popular sense to meet what was certainly until very lately the general popular impression, that a geological period has, in the region where it has been studied and defined, something like a beginning and an end; that it is bounded by periods of change—elevation, denudation, or some other evidence of the lapse of A THE DEPTHS OF THE SEA. [cHar. x. unrecorded time; and that it would be inadmissible to speak of two portions of the same continuous deposit, however distant the times of their deposition might be, and however distinct their imbedded faunze, as belonging to different ‘Geological periods.’ It was certainly in this sense that in an address to a popular audience in April 1869 I ventured to state my belief that it is not only chalk which is being formed in the Atlantic, ** but the chalk, the chalk of the cretaceous period.”’ Sir Charles Lyell says, in summing up his objections to this view,’ ‘“ The reader will at once perceive that the present Atlantic, Pacific, and Indian oceans, are geographical terms which must be wholly without meaning when applied to the eocene, and still more to the cretaceous period, so that to talk of the chalk having been uninter- ruptedly formed in the Atlantic is as inadmissible in a geographical asin a geological sense.’ I confess I do not see the geographical difficulty ; the “Atlantic ocean”? is, undoubtedly, a geographical term, but the depression under discussion occupies the area at present expressed by that term, and to use it seems to be the simplest way of indicating its position. We believe that the balance of probability is greatly in favour of the chalk haying been unin- terruptedly forming over some parts of the area in question, and our belief is founded upon many con- siderations, physical and paleontological. All the principal axes of elevation in the north of Europe and in North America have a date long an- terior to the deposition of the tertiary, or even of the 1 The Student’s Elements of Geology. By Sir Charles Lyell, Bart., F.R.S. London, 1871. P. 265. CHAP. X.] CONTINUITY OF THE CHALK. 473 newer secondary beds, although some of them, such as the Alps and the Pyrenees, have received great acces- sions to their height in later times. All these newer beds have therefore been deposited with a certain re- lation in position to certain main features of contour which are maintained to the present day. Many oscil- lations have doubtless taken place since, and every spot on the European plateau may have probably alternated many times between sea and land; but it is difficult to show that these oscillations have occurred in the north of Europe to a greater extent than from 4,000 to 5,000 feet, the extreme vertical distance be- tween the base of the tertiaries and the highest point at which tertiary or post-tertiary shells are found on the slopes and ridges of mountains. ) 2 =a Planorbulina lobatula, W.andJ. . = | | Pulvinulina micheliana, D’ORBIGNY . =| Spiroplecta biformis, P.and J... Se |e Vernewlina triquetra, VoN M.. . . (=o) Olea polystropha, Reuss ae i | a = 99 99 1 Wonders of Geology, 6th edition, 1848. Vol. i. p. 305. 2 Saturday Review. CHAP. X.] CONTINUITY OF THE CHALK. 479 And the following table, showing the number of foraminifera common to the Atlantic mud and various eeological formations in England :-— Common to the following Formations. Total ss —— SSS ase. val ee Rhetic | eat ae tong | London ene Upper Lower and Per- | Carbo- | sulniites |) CRIs clay. Chalk. | Jurassic. | Jurassic. Upper mian. | niferous. | Trias. | | m0) 53°) 28 4 19 7 7 7 ey i The morphology of the foraminifera has been studied with great care, and the differences between closely allied so-called species are so shght that it is possible that in many cases they should only be regarded as varieties; but this careful criticism and appreciation of minute differences renders it all the more likely that the determinations are correct, and that animal forms which are substantially identical have persisted in the depths of the sea during a con- siderable lapse of geological time. In the late deep-sea dredgings by M. de Pourtales off the American coast, and by H.M. ships ‘ Light- ning’ and ‘ Porcupine,’ and Mr. Marshall Hall’s yacht ‘Norna’ off the west coast of Europe, no animal forms have been discovered belonging to any of the higher groups, so far as we are as yet aware, speci- fically identical with chalk fossils; and I do not think that we have any right to expect that such will be found. Toa depth of 5,000 feet or so a large portion of the North Atlantic is at present heated very con- siderably above its normal temperature, while the Arctic and Antarctic indraught depresses the bottom 480 THE DEPTHS OF THE SEA. [ CHAP. X. temperature in deep water to a like extreme degree. These abnormal temperatures are dependent upon the present distribution of sea and land; and I have already shown that we have evidence of many oscillations, in modern times geologically speaking, which must have produced totally different condi- tions of temperature over the same area. Accepting, as I believe we are now bound to do in some form, the gradual alteration of species through natural causes, we must be prepared to expect a total absence of forms identical with those found in the old chalk, belonging to groups in which there is sufficient structural differentiation to require or to admit of marked variation under altering circumstances. The utmost which can be expected is the persistence of some of the old generic types, and such a resemblance between the two faunze as to justify the opinion that, making due allowance for emigration, immigration, and extermination, the later fauna bears to the earlier the relation of descent with extreme modi- fication. I have already mentioned that one of the most remarkable differences between the recent Atlantic chalk-mud and the ancient white chalk is the total absence in the latter of free silica. It would seem, from the analysis of chalk, that silicious organisms were entirely wanting in the ancient cretaceous seas. In the chalk mud, on the other hand, silica is found in abundance, in most specimens to the amount of from 80 to 40 per cent. A considerable portion of this is inorganic silica—sand; and its presence is doubtless due to the circumstance that our dredgings have hitherto been carried on in the neighbourhood CHAP. x. | CONTINUITY OF THE CHALK. 48] of land and in the path of slight currents, whilst the extreme purity of the white chalk of Sussex would seem to indicate that it had been laid down in deep still water far from land. A considerable proportion of the silica of the chalk-mud, however, consists of the spicules of sponges, of the spicules and shields of radiolarians, and of the frustules of diatoms; and this organic silica is uniformly distributed through the whole mass. Taken in connection with the absence of diffused silica in the white chalk, we have the singular fact of the presence of regular layers of flinty masses of nearly pure silica, pre- senting frequently the external form of more or less regularly-shaped sponges, and frequently filling up the cavities of sea-urchins or bivalve shells. If we take the simple instance of pure grey flint filling up entirely the cavity of an urchin, such as Ga/le- rites albo-galerus, or Ananchytes ovatus, and. showing at the oral opening of the shell a little projecting knob, lke a bullet-mould filled with lead, we have no escape from the conclusion that after the death of the urchin the silica has percolated into the shell in solution or in a gelatinous condition, and the silica must have previously existed in some other form, either in the chalk or elsewhere. In the chalk which contains not a trace of silica we often find the moulds and outlines of organisms which we know to have been silicious, from which the whole of the silica has been removed; and I have more than once seen cases in which a portion of the delicate tracery of a silicious sponge has been preserved entire in a flint, while the remainder of the vase which projected beyond the outline of the flint appeared in the chalk as a trellis- se 482 THE DEPTHS OF THE SEA. [cHap. x. work of spaces, vacant, or loosely filled with peroxide or carbonate of iron. It therefore seems certain that by some means or other the organic silica, distributed in the shape of sponge spicules and other silicious organisms in the chalk, has been dissolved or reduced to a colloid state, and accumulated in moulds formed by the shells or outer walls of imbedded animals of various classes. How the solution of the silica is effected we do not precisely know. Once reduced to a colloid condition, it is easy enough to imagine that it may be sifted from the water by a process of endosmose, the chalk matrix acting as a porous medium, and accumulated in any convenient cavities. In various localities in the chalk and green-sand of the North of England the peculiar bodies which are called Ventriculites are excessively abundant,—ele- gant vases and cups with branching root-like bases, or groups of regularly or irregularly spreading tubes, delicately fretted on the surface with an impressed network like the finest lace. In the year 1840 the late Mr. Toulmin Smith published the result of many years’ careful study of these bodies, and gave a minute and most accurate description of their structure. He found them to consist of tubes of extreme tenuity, delicately meshed, and having be- tween them interspaces usually with very regular cubial or octohedral forms. These tubes in the Ven- triculites found in chalk were empty, or contained a little red ochreous matter ; but when a ventriculite or a portion of one happened to be entangled in a flint, it was either incorporated with the flint or replaced by silica. Mr. Toulmin Smith supposed that the skeleton of the ventriculite had been originally calcareous, CHAP, X.| CONTINUITY OF THE CHALK. 483 and he referred the group to the Polyzoa. When Mr. Toulmin Smith studied the Ventriculites, the Hexactinellida—the sponges with six-rayed meshes or spicules—were practically unknown, though there Fic. 80.—Ventriculites simplex, TouLMuin SmitH. Once and a half the natural size. were already a few examples in museums. One of the first results of deep-sea dredging was the discovery that the chalk-mud of the deep sea is in many places literally crowded with these; and when we compare Thee A84 THE DEPTHS OF THE SEA. ' [erap. x, such recent forms as Aphrocallistes, Iphiteon, Hol- tenia, and Askonema with certain series of the chalk Ventriculites, there cannot be the slightest doubt that they belong to the same family—in some cases to very nearly allied genera. Fig. 80 represents a very beautiful specimen of Ventriculites simplex preserved in flint, for which I am indebted to Mr. Sanderson of Edinburgh. Looking at this in the light of our knowledge of Huplectella or Aphrocuallistes beatriz, we have no difficulty in working out its structure, even to the most minute microscopic detail. Other sponges, belonging chiefly to the Lithistidee and the Corticatze, re- produce with wonderful accuracy the more irre- gular sponge-forms of the chalk and _ green- sand; and a group, as yet undescribed, but apparently an aberrant family of the Esperiade, send out long delicate a Pocono ees eee ee ee shghtly, but in a most characteristic way, at the point of their insertion into the sponge body, recalling very forcibly the peculiar manner in which the tube-like root processes join the sponge in such genera as the vaguely defined Choanites. One sponge belonging to the group is represented at Fig. 838. A sphere 15 to 20 mm. in diameter con- sists of a smooth glossy external rind, composed of closely meshed pin-headed spicules, with two kinds be Sh VV The. IH &( A) CHAP. X.] CONTINUITY OF THE CHALK. 485 of ‘spicules of the sarcode,’ one large, C-shaped, the other much more minute, answering to Bowerbank’s ‘tridentate equianchorate’ type; every now and then Fic. 82.—Ventriculites simplex, TouLMIN Smirn. Section of the outer wall, showing the structure of the silicious network. (x. 50.) the rind thus formed coming to the margin of a small pore. The interior of the sphere is filled with soft semi-fluid sarcode, supported by the loosest possibie Fic. 83.—Celosphera tubifex, WYVILLE THoMson. Slightly enlarged. Off the coast of Portugal. mesh-work of granular horny matter and_pin- headed spicules. From points apparently irregularly placed on the surface of the sponge, tubes about 3 mm. in diameter run out in all directions; the walls of the tubes are thin and delicate, being A86 THE DEPTHS OF THE SEA. [CHAP. X. more so towards the distant ends, where the tubes contract slightly to an open orifice. At the proximal end, at the junction between the tube and the sponge body, there is also a contraction, and a slight pit-like involution of the surface of the sponge. Fic. 84.—‘ Choanites.’ Ina flint from the white chalk. There is something very characteristic in this pecu- liar form of junction which it is not easy to define, but which almost forces the conviction that there is the closest relation between these recent forms and tube-bearing fossil sponges such as Choanites. Professor Martin Duncan mentions several corals CHAP, X.] CONTINUITY OF THE CHALK. 487 from the coast of Portugal more nearly allied to chalk forms than to any others, but it is in the Echinodermata that the peculiar relation between the ancient and the modern faunze becomes most apparent. ‘To review briefly the chief points bearing upon this question. The Apiocrinide, the group of fixed crinoids which I have already described, are abundant throughout the whole range of the Jurassic rocks, their remains being frequently very abundant in the thick cream-coloured limestone beds of the oolites. Towards the close of the Jurassic period, the typical genera disappear, and in the chalk we find the group represented by an evidently degenerate form, Bourguetticrinus. In some tertiary-beds frag- ments of the stems of a small Bourguetticrinus have been found, and such were likewise discovered in the recent lime breccia of Guadaloupe, which con- tained the well-known human skeleton now in the British Museum. There can be little doubt that these tertiary and post-tertiary fragments are to be referred rather to the genus Rhizocrinus, which we now know to be so widely distributed, living, in deep water. Now in this series of Apiocrinidee, extending from the Forest marble to the present time, although there is a succession of constantly changing species, yet the gradual degradation in development in the same direction throughout the series seems to point unmistakeably to some form of continuity, to a type gradually succumbing to con- ditions slowly altering in an unfavourable direction. The other family of the stalked crinoids, the Pentacrinide, are in a different position. They are abundant in the Lias; very abundant in the lower 488 THE DEPTHS OF THE SEA. [cHaP. xX. oolite, where slabs are often found almost made up of them, with a characteristic deep-water association of Cidaris, Astrogonium, and Astropecten; and al- though not abundant in the English chalk, several species are found, and these show no tendency to degeneracy. As might be expected, such remains are rare in the shallow-water tertiaries. With regard to their distribution in modern seas, from the apparent abundance of P. asteria and P. miillert in deep water in the West Indies, and of P. wyville- thomsoni off the coast of Portugal, it is very pos- sible, as I have already said, that they may occupy a much more important place in the abyssal fauna than we at present imagine. Nearly all the additions from the deep water to the list of the Asteridea fall into the genera Archaster and Astropecten, or into the various sub- divisions of the old genus Goniaster. From their breaking up into a multitude of undistinguishable ossicles by the decomposition of their soft organic matter immediately after death, the fossil remains of star-fishes are comparatively rare, and are scarcely met with except in fine calcareous formations, such as the Wenlock limestone—and in later times in the fine yellow limestones of the oolites, and in the white chalk. In the latter formation, deposited ap- parently very much under the same circumstances as the Atlantic chalk-mud, the general character of the group of imbedded star-fishes is almost the same as in the modern fauna of the deep Atlantic. The Echinidea are a more typical order. From the compactness of their tests they are more readily preserved entire, and from the earliest periods their CHAP. X. | CONTINUITY OF THE CHALK. 489 characteristic and harmoniously varying series are of censiderable value in the discrimination of the different formations. In the soft white chalk of the south of England their remains are extremely abun- dant. Perhaps the most abundant and characteristic fossils in the chalk are the Cidaridze, and these more than any other chalk fossils illustrate the peculiar conditions under which the chalk has been laid down. The great spines of Cidaris are attached to the plates of the shell by a central ligament which passes from the cup on the spine to a perforation in the ball on the plate, and by a membrane which rises from the plate and passes over the base of the spine. The spines are, however, so disproportionately large, and the soft matter softens and decomposes so rapidly after death, that it is difficult to keep the spines attached to a specimen prepared even with consider- able care. In the chalk, tests of Cidaris are fre- quently preserved absolutely entire, with all the spines in position ; so that by carefully working out the chalk with a penknife, we can here have the whole animal perfect. It is difficult to see precisely how this result can have been produced. The urchin must have sunk into the soft chalk-mud and been covered up by a sufficient quantity to support its spines and test, and allow the whole to become gradually compacted into a solid mass. One of the new deep-sea Cidarites belongs to a genus which had previously been supposed to be extinct, but the chalk-mud forms generally do not show any special approach to any particular chalk species. Still the general character of the group is the same. The Echinothuridz were previously known only as chalk 490 THE DEPTHS OF THE SEA. (CHAP. X. fossils, so that their presence apparently in abun- dance in the recent chalk-mud is a clear instance of the preservation of one of the old types hitherto supposed to be extinct. ‘The same may be said of Pourtalesia, which must associate itself either with Ananchytes or with Dysaster, both of which are types of groups likewise supposed to have been lost. We thus find that, while no Echinoderm hitherto discovered in the deep water is specifically identical with any chalk form, not only does the abyssal fauna with its abundance of the Cidaridee, Echinothuride, and irregular urchins, and the disproportionate num- bers of the genera Astropecten, Astrogonium, and Stellaster, and their allies among starfishes, singu- larly resemble the chalk in general facies; but several genera approach chalk forms more closely than they do any hitherto known in a living state— approach them so closely as almost to force upon us the conviction that their relation is one of descent, accompanied by change of conditions and consequent modification, though not to any extreme degree. As I have already stated, the whole of the mol- lusca from the deep water which had been previously described as fossils were known from tertiary and post-tertiary beds; with the very doubtful exception of our common Terebratulina caput-serpentis, which certainly approaches very closely Terebratula striata from the chalk. It is not surprising that this should be the case. It is a marked character of the European Tertiaries that with the exception of some of the older beds in the south of Europe, all of them have been deposited in shallow water; so that the tertiary beds represent CHAP. X.] CONTINUITY OF THE CHALK. 491 the mineral accumulations and the fauna of the margin of some sea. We may say that they have been deposited in the shallow water of tertiary seas whose deep-sea fauna is unknown, and this mode of expres- sion is most in accordance with previous ideas; but if the view here advocated be correct, we must regard the tertiaries as the deposits formed and exposed by depressions and upheavals of the borders of the cre- taceous sea; of a sea which, with many changes of condition produced by the same oscillations which alternately exposed and submerged the tertiaries, existed continuously, depositing conformable beds of chalk-mud from the period of the ancient chalk. Mollusca are chiefly shallow-water forms, although some of them are special to deep water, and others have a great vertical range. As I have already said, considering the many changes in the conditions which most affect animal life which have occurred during later geological times, we cannot expect to find any animals of the higher groups specifically identical with chalk fossils; the difficulty in the case seems rather to be to account for the identity of many living deep-water species with species found in the Tertiaries. I think, however, that we can find a clue. Most of the species common to the modern Atlantic and to tertiary beds are now found in the Atlantic at much greater depths than those at which they were imbedded in the tertiary seas. This we know by the species from shallower water which are associated with them in the Tertiaries. They are, therefore, species which had a considerable vertical range; and probably while many of the shallower water forms were exterminated by elevations or other change 492 THE DEPTHS OF THE SEA. [CHAP. X. affecting the first one or two hundred fathoms, they were enabled to survive, the deeper part of their habitat having suffered but little alteration. Sir Charles Lyell says: “The reader should be reminded that in geology we have been in the habit of founding our great chronological divisions, not on foraminifera and sponges, nor even on echinoderms zr corals, but on the remains of the most highly organized beings available to us, such as mollusca. . . . In dealing with the mollusca, it is those of the highest or most specialized organizations which afford us the best characters in proportion as their vertical range is the most limited. Thus the cephalopoda are the most valuable, as having a more restricted range in time than the gasteropoda, and these again are more characteristic of the particular stratigraphical sub- divisions than the lamellibranchiate bivalves, while these last again are more serviceable in classification than the brachiopoda, a still lower class of shell-fish, which are the most enduring of all.” With great deference to Sir Charles Lyell, I cannot regard the most highly specialized animal groups as those most fitted to gauge the limits of great chronological divisions, though I admit their infinite value in determining the minor subdivisions. The culmination of such animal groups, such as we find in the marvellous abundance and variety of both orders of cephalopods at the end of the Jurassic and the commencement of the cretaceous period, undoubtedly brings into high relief, and admirably illustrates to the student, the broad distinctive cha- racters of the mesozoic fauna; but speaking very generally, the more highly a molltse is specialized CHAP. x. | CONTINUITY OF THE CHALK. 493 the shallower is the water which it inhabits. The cephaiopods are chiefly pelagic and surface things, and their remains are consequently found in deposits from all depths. To this general pelagic distri- bution of cephalopods there seem to be two re- markable exceptions, and these the two members of their class which are by far the most interest- ing in their geological relations. Nautilus pom- puius inhabits the deep water of the Pacific, while the habitat of Spirula australis is unknown. The shell of Spirula is thin and light, and, probably after the death of the animal and by the decom- position of organic matter, it becomes filled with air, and the emptied shell floats, and is drifted along on the surface of the sea. Tropical shores are strewn with the pearly little coil, which attracts attention by the elegance of its form. It is abundant on all shores in the path of the Gulf-stream. Sysselmann Miiller gave me, afew years ago, a quantity which had been drifted on the south-western shores of different islands of the Feéroe group. Still the structure of the animal of Spirula may be said to be unknown. One specimen only, which was described by Professor Owen, was found nearly perfect on the coast of New Zealand by Mr. Percy Noel. I suppose there can be little doubt that this is a deep-water form, and I hope that with our deep-sea dredging we shall soon clear up its economy ; but inthe meantime the evident abundance of the animal and our ignorance of its history are very suggestive. In the London clay one or two examples of a fossil have been found, nearly allied to Spirula, but differing in this respect—that a solid conical rostrum projects backwards, its half-calcified, half- 494 THE DEPTHS OF THE SEA. [cnMAP. X. horny substance enclosing the greater part of the curved spiral shell. Now if the recent Spirula had been weighted with such a rostrum it would probably have remained up to the present time utterly unknown to us. It is unwise to prophesy, but I certainly look upon some form allied to Spirulirostris as one of the most likely spoils of the deep sea. From the Tertiaries we pass to the Cretaceous forms, and find in Belemnitella the chambered shell straightened and reduced, and the ‘guard’ greatly increased in size. If Belemnites were deep-sea animals, as seems very probable, and if any of them still exist,—-from the form and weight of their shells it is scarcely possible that they should ever be thrown up on the shore, and without deep-sea dredging they might remain for ever unknown. I merely mention this to show that it is by no means safe to base even what little argument might rest upon it, upon the absence at the present time of all representatives of the cretaceous cephalopodous fauna. The gasteropods, with comparatively few excep- tions, range from the shore to a depth of 100 to 200 fathoms, and lamellibranchs become scarcer at a slightly greater depth; while some orders of bra- chiopods, crustacea, echinoderms, sponges, and fora- minifera, descend in scarcely diminished numbers to a depth of 10,000 feet. In fact, the bathymetrical range of the various groups in modern seas corre- sponds remarkably with their vertical range in ancient strata. A change in the distribution of sea and land in- - volving a mere change in the course of an ocean- current might modify the conditions of an area for CHAP. -X. ] CONTINUITY OF THE CHALK. 495 most cephalopods and all pteropods, heteropods, and other surface living animals of high type, even to their extinction. By oscillations of 500 feet up or down, the great mass of gasteropods, and all reef- building corals, would be forced to emigrate, would become modified, or would be destroyed,—and another hundred fathoms would exterminate the greater num- ber of bivalves; while elevations and depressions to ten times that amount might only slightly affect the region of brachiopods, echinoderms, and sponges. After a careful consideration of the results of recent investigations, we are strengthened in our confidence in the truth of the opinion which we previously held, that the various groups of fossils characterizing the tertiary beds of Europe and North America represent the constantly altering fauna of the shallower por- tions of an ocean whose depths are still occupied by a deposit which has been accumulating continuously from the period of the pre-tertiary chalk, and which perpetuates with much modification the pre-tertiary chalk fauna. I do not see that this view militates in the least against the ‘“‘ reasoning and classification”’ of that geology which we have learned from Sir Charles Lyell; our dredgings only show that these abysses of the ocean—abysses which Sir Charles Lyell admits in the passage quoted above, to have outlasted on account of their depth a succession of geological epochs—are inhabited by a special deep-sea fauna, possibly as persis- tent in its general features as the abysses themselves. I have said at the beginning of this chapter, that I believe the doctrine of the ‘continuity of the chalk,’ as understood by those who first suggested it, now meets with very general acceptance : and in evidence 496 THE DEPTHS OF THE SEA. [cwap.:x of this I will quote two passages in two consecutive anniversary addresses by Presidents of the Geological Society, and we may have every confidence that the statements of men of so great weight, made under such circumstances, indicate the tendency of sound and judicious thought. Professor Huxley, in the anniversary address for the year 1870, says :—‘* Many years ago' I ventured to speak of the Atlantic mud as ‘modern chalk,’ and I know of no fact inconsistent with the view which Professor Wyville Thomson has advocated, that the modern chalk is not only the lineal descendant, so to speak, of the ancient chalk, but that it remains, so to speak, in possession of the ancestral estate; and that from the cretaceous period (if not much earlier) to the present day, the deep sea has covered a large part of what is now the area of the Atlantic. But if Globigerina and Terebratula caput-serpentis and Beryx, not to mention other forms of animals and of plants, thus bridge over the interval between the present and the mesozoic periods, is it possible that the majority of other living things underwent a sea-change into something new and strange all at once ?” And Mr. Prestwich, in the presidential address for 1871, says :—‘ Therefore, although I think it highly probable that some considerable portion of the deep sea-bed of the mid-Atlantic has continued submerged since the period of our chalk, and although the more adaptable forms of life may have been transmitted in unbroken succession through this channel, the im- migrations of other and more recent faunas may have so modified the old population, that the original 1 Saturday Review, 1858: ‘Chalk, Ancient and Modern.” CHAP. X.] CONTINUITY OF THE CHALK. 497 chalk element is of no more importance than is the original British element in our own English people.” Mr. Prestwich thus fully admits the high pro- bability of the ‘ continuity’ for which we contend. The last question which he raises in the sentence quoted is one of enormous difficulty, which we have as yet no data to solve. It is perhaps not very much harder, however, after all, than the problem in ethno- logy which he has selected as an illustration. Several other very important questions bearing upon the conditions of the ocean at great depths, occupied the attention of the naturalists in scientific charge of the dredging cruises of the ‘ Lightning’ and ‘ Porcupine.’ An assistant versed in the methods of chemical and physical research accompanied the vessel on each occasion. A son of Dr. Carpenter, Mr. William Lant Carpenter, B.A., B.Sc., went on the first cruise with Mr. Jeffreys. Mr. John Hunter, F.C.S., a promising young chemist, since deceased, accompanied me to the Bay of Biscay, and Mr. Her- bert Carpenter, a younger son of my colleague, was our companion during the third long cruise in the Froe channel. The specific gravity of the water was taken at each station, and in the serial soundings the water- bottle was let down to the intermediate depths and the water carefully tested. The differences observed were very slight, but they were as a rule confirmatory of Professor Forschammer’s opinion that Arctic water contains less salt than the sea-water of temperate and intertropical regions. As I have already mentioned (page 46), organic matter in appreciable quantity was detected by the K K 498 THE DEPTHS OF THE SEA. (CHAP. X. permanganate test everywhere, and at all depths. The gas contained in the water was carefully ana- lysed, and it was found, as a general result, that the amount of free carbon dioxide increased and the proportion of oxygen diminished with increased depth. ‘There seemed to be reason to believe, how- ever, that the quantity of carbon dioxide depended to a great degree upon the abundance of the higher forms of life. Mr. Lant Carpenter used always to predict a bad haul for the zoologists when he found the proportion of carbon dioxide to the oxygen and nitrogen unusually low. ‘The great increase in the quantity of carbon dioxide was just above the bottom. The general average of thirty analyses of surface- water gives the following as the proportions of the contained gases present :—Oxygen 25:1, nitrogen 542, carbon dioxide 20°7; this proportion was subject, however, to great variations. Intermediate water gave an average percentage of oxygen 22°0, nitrogen 52°8, and carbon dioxide 26:2; while bottom-waters gave—oxygen 19°5, nitrogen 52:6, and carbon dioxide 27°9. But bottom-water, at a comparatively small depth, often contained as much carbon dioxide as intermediate water at much greater depths. In one of the serial soundings, in which the water was taken at every 50 fathoms, three analyses gave the following singular result :— 750 fathoms. 800 fathoms. Bottom, 862 fathms. Oxygenye., fa). 26) 188 17°8 Lii-2 Nitrogen, ifs. = 49:3 48°5 34°5 Carbon dioxide . . 31:9 a3°7 48°3 The greatly increased percentage of carbon dioxide in the stratum of sea-water immediately overlying CHAP, x.] CONTINUITY OF THE CHALK. 499 the sea-bed, was here accompanied by a great abun- dance of animal life. | I can scarcely regret that the space at my disposal will not allow me fo enter at present into the many very important bearings of these physical investiga- tions, for I am compelled to admit that I do not place thorough confidence in our results. The obser- vations and analyses were undoubtedly conducted with great care and skill, but the difference between different samples—in specific gravity, and more espe- cially in chemical composition and the relative pro- portion of the ingredients—is so very slight, that more exact methods than those which have been hitherto employed will be required to insure accurate results. In such investigations everything depends upon the perfection of the means of bringing up water from any given depth; and the principle of the construction of the water-bottle used in the ‘ Por- cupine’ was faulty. It consists of a strong tube of brass about two feet in length and two inches in internal diameter, containing rather more than a litre and a half, and closed at each end by a brass disk. In the centre of each of these disks there is a round aperture closed by a well-ground conical valve, both valves opening upwards when the instru- ment is in position for being let down. In passing down through the water, a continuous current is supposed to raise the valves and run through the bottle, thus keeping it constantly filled with the water of the layer through which it is passing. On reversing the motion in hauling up, the valves fall into their places, and the contents of the tube at the greatest depth are brought to K KZ 500 THE DEPTHS OF THE SEA. [cHaP. X. the surface. This bottle appeared to answer fairly, and we often had evidence, from its turbidity, that bottom-water came up; but subsequent experiments have shown that it cannot be depended upon, and some of the reasons are sufficiently obvious. The instrument will not work at all unless the descend- ing motion be sufficiently steady and rapid to main- tain a current capable of keeping two heavy brass valves open to their full extent; if there be the slightest reversal, or jerk, or irregularity in hauling up, the water is—at all events partially—changed ; the two valves, even when thoroughly open, are directly in the path of the ingress and egress of the water—and there is reason to believe that the water is not so rapidly and thoroughly changed as we at first imagined. A perfectly satisfactory water- bottle is still a desideratum, but I believe that one which was used by Dr. Mayer and Dr. Jacobsen in the German North Sea expedition of the past summer, goes far to remedy most of these defects. I hope we may be in a better position to give an opinion a year hence. I give, in the appendix to this chapter, an abstract of the general results of the chemical investigations carried on during the ‘ Porcupine’ cruises of 1869 ; and I add a note, for which I am indebted to my friend Mr. J. Y. Buchanan, who accompanies me as chemist to the ‘Challenger’ expedition, which will show how much has yet to be done before we can hope to come to any really satisfactory conclusion as to the amount and condition of the gases con- tained in sea-water. Neither, I regret to say, can we place much reliance on the determination of CHAP. X.] CONTINUITY OF THE CHALK. DOE organic matter in sea-water by the permanganate method, although there is every probability that the general result at which we arrived—that organic matter is contained in the water of the ocean in all localities and at all depths—is substantially true. The application of the exact methods of modern science to this lne of inquiry is new, -and it will require long and patient work to bring it to per- fection. The one real advance which has been made in this direction is the addition to the appliances for the investigation of the physics of the deep sea; of a correct and trustworthy instrument by which ocean temperatures can be ascertained to any depth with what may be regarded as absolute accuracy for all practical purposes. KUNO, FROM VAAY IN BORDO. 502 THE DEPTHS OF THE SEA. (CHAP: X. APPENDIX A. Summary of the Results of the Examination of Samples of Sea- Water taken at the Surface and at various Depths. By Wm. LANT CARPENTER, B.A., B.Sc. Surface-waters.—Care was taken to obtain these samples as pure as possible, and free from any contamination caused by matters derived froin the vessel, by dipping them up in clean vessels at a few inches below the surface at or near the bow of the ship. In two instances, however, the samples were taken from abaft the paddles. Waters taken at depths below the surface.—It was found desirable to coat the brass Water-Bottles internally with sealing-wax varnish, owing to the corrosive action of the sea- water. The apparatus was then found to work perfectly satis- factorily in all cases in which there was sufficient weight on the sounding-line to which they were attached to keep the bottles perpendicular, or nearly so. When, from the smallness of the attached weight, or the roughness of the sea, the sounding-line was at an acute angle with the general level of the sea-surface while it was being drawn up, the results of the examination of water thus obtained rendered it highly probable that some water at or near the surface had found its way into the bottle, and that its contents were not to be relied on as coming from the lowest depths. When bottom-water was obtained from depths beyond 500 fathoms, it was almost invariably charged with a quantity of very fine mud in suspension, rendering it quite turbid. Many hours’ standing was necessary for the deposit of this ; but it was readily removed by filtration. In no instance was there any evidence of water from great depths being much more highly CHAP. X.] CONTINUITY OF THE CHALK. 503 charged with dissolved gases than surface-waters ; a considerable elevation of temperature being in all cases necessary for the evolution of any dissolved gas. Mode of examining Sanvples—The samples of water thus taken were examined with as little delay as possible, with a view to determine :— (1) The specific gravity of the water. (2) The total quantity of dissolved gases contained in them, and the relative proportions of oxygen, nitrogen, and carbonic acid. (3) The quantity of oxygen necessary to oxidize the organic matter contained in the water; distinguishing between a, the decomposed organic matter, and b, the easily decomposable organic matter. (1) The specific-gravity determinations were made at a tem- perature as near 60° Fahr. as possible, with delicate glass hy- drometers, so graduated that the specific gravity could be read off directly to the fourth decimal place with ease. (2) The apparatus for the analysis of the gases dissolved in the sea-water was essentially that described by Prof. Miller in the second volume of his ‘Elements of Chemistry.’ It was found necessary to make several modifications in it, to adapt it to the motion of the vessel. These consisted chiefly in sus- pending much of it from the cabin-ceiling, instead of supporting it from beneath, and in rendering all the parts less rigid by a free use of caoutchouc tubing, &c., the utmost care being taken to keep all joints tight. . It was found possible to make correct analyses, even when the vessel was rolling sufficiently to upset chairs and cabin- furniture. The method of analysis may be thus summarized :—From 700 to 800 cubic centimetres of the sample to be examined were boiled for about thirty minutes, in such a way that the steam and mixed gases evolved were collected over mercury in a small graduated Bunsen’s gas-holder, all access of air being carefully guarded against. The mixed gases were then trans- ferred to two graduated tubes in a mercurial trough, where the 504 THE DEPTHS OF THE SEA. [CHAP. x. carbonic acid was first absorbed by a strong solution of caustic potash; and subsequently the oxygen was absorbed by the addition of pyrogallic acid, the remaining gas being assumed to be nitrogen. The results of the analyses were always corrected to the standard temperature of 0° Cent., and to 760 millimetres’ baro- metric pressure, for comparison among themselves and with others. In nearly every case the duplicate analyses from the same gaseous mixture agreed closely, if they were not identical. (3) The examination of the sea-water for organic matter was made according to the method detailed by Prof. Miller in the Journal of the Chemical Society for May 1865, with an addition suggested by Dr. Angus Smith. Each sample of water was divided into two; to one of these a little free acid was added, and to both an excess of a standard solution of permanganate of potash. At the end of three hours the reaction was stopped by the addition of iodide of potassinm and starch, and the excess of permanganate estimated by a standard solution of hyposulphide of soda. The portion to which free acid was added gave the oxygen required to oxidize the decomposed and easily decomposable organic matter; the second portion gave the oxygen required by the decomposed organic matter alone, which was usually from about one-half to one-third of the whole. The following is a summary of the total number of obser- vations, analyses, &c., made during the three cruises respec- tively :— | First | Second} Third Total. | ernise. | cruise. | cruise. Specific-gravity determinations .| 72 27 26 | 125 | Duplicate gas-analyses . . . .| 45 | 28 21 89 Organic-matter tests. . . . .| 137 96 | 32 | 195 Specific Gravity—The specific gravity of surface-water was found to diminish slightly as land was approached; but the « CHAP. X.] CONTINUITY OF THE CHALK. 505 average of thirty-two observations upon water at a sufficient distance from land to be unaffected by local disturbances was 1:02779, the maximum being 1:0284 and the minimum 1:0270. - It was almost always noticed that, during a high wind, the specific gravity of surface-water was above the average. The average of thirty observations upon the specific gravity of intermediate water was 1:0275, the maximum being 1:0281 and the minimum 1:0272. The specific gravity of bottom-waters at depths varying from 77 to 2,090 fathoms, deduced from an average of forty-three observations, was 1:0277, the maximum being 1:0282 and the minimum 1°0267. It will be noticed that the average specific gravity of bottom- water is slightly less than that of surface-water. In several instances the specific gravities of surface- and of bottom-waters taken at the same place having been compared, that of the bottom-water was found to be appreciably less than that of the surface-water. Thus— At 1,425 fathoms’ depth (Station 17) it was . . 1°0269 Suriacerathersaneme es) eo eee ae el cO260 And At 664 fathoms’ depth (Station 266) it was . . 1°0272 Surlacerababhbersamie: os ats es bens ell ee ean een ee SGOZ80 According, however, to a series of observations made at the same spot (Station 42) at intervals of fifty fathoms, from 50 to 800, the specific gravity increased with the depth from 1:0272 at 50 fathoms to 1:0277 at 800 fathoms. Several series of specific-gravity observations were made near the mouths of rivers and streams; showing the gradual mixture of fresh and salt water, and the floating of lighter portions above the denser sea-water, as well as the reverse effect produced by the influence of tidal currents. Thus outside Belfast Lough a rapid stream of water of specific gravity 1:0270 was found above water which, at a depth of seventy-three fathoms, had a specific gravity of 1:0265. Gases of Sea-water.—The analyses of the gaseous constituents of sea-water may be divided into two groups: (1) Analyses of 506 THE DEPTHS OF THE SEA. [CHAP. X. surface-waters. (2) Analyses of waters below the surface ; and these last may be again subdivided into (a) fafa and (6) bottom-waters. Second Cruise | Third Cruise . The total quantity of dissolved gases in sea-water, whether at the surface or below it, was found to average about 2°8 volumes in 100 volumes of water. The average of thirty analyses of surface-waters made during the expedition gave the following proportions :— Percentage. Proportion. Oxygen), =. ..... 25046 100 Nitrogen 4. > 2+. ( 54°21 216 Carbonicacid. . . 20°743 80 1007000 These were thus distributed over the three cruises, and the maxima and minima of each constituent are thus shown :— Carbonie | Average per- Average Oxygen. Nitrogen. Aveta centage. proportion. analyses. | Salles Car- Max. | Min. | Max. | Min. | Max. | Min Eey- ae bonic 0. | N. |CO,| per | per | per | per | per | per Ben | Sen. | acid. | cent. | cent. | cent. | cent. | cent. | cent. Number of First Cruise . | 19 | 24°47 | 52°95 | 22-58 moO 16 92 | 28°78 | 19°60 | 62°95 | 46°35 | 32°0 | 12°72 | 31:33 | 54°85 | 13°82 | 100) 175/ 44 | 37-10 | 25-36 | 59°63 | 60-07 | 24-37] 38-27 bo © 24°86 | 66°73 | 18°41 100 | 228| 74 | 45°28 | 18°98 | 68°67 | 41°42 | 27°14] 5-64 It is interesting to remark that surface-water contains a greater quantity of oxygen and a less quantity of carbonic acid during the prevalence of strong wind. The following is an average of five analyses made under such conditions :— Per cent. Proportion. General average. Oxygem* =. 2: BSG 100 25°046 100 iINvbropeny (b