S,U^^' JOURNAL OF NATURAL PHILOSOPHY, CHEMISTRY, AND THE ARTS, VOL. VIL SllluSttateB toit{) (JEngtatJingsf* BY WILLIAM NICHOLSON. ■*" ' ■ ■ ■ I .11.-1 ■ » ' ' '■- LONDON: PRINTED BV \\\ STRATFORD, CROWN^OURT, TEMPLE-BAR, FOR THE A'XJTHOR, No. 10, SOHO-SQUARE; AND SOLD BY G. AND J. ROBINSONS, PArERNOSTER-ROW. 180*, #' w sl^^, ADVERTISEMENT. X HE Authors of Original Papers iri the present Volume, are Joseph Huddart, Esq. F. R. S. ; John Dalton ; Everard Home, Esq. F. R. S. ; Mr. John Gough ; Robert Briggs, M. D. ; Mr. Ezekiel Walker; Mr. John Farcy; Mr. Fre- derick Accum; Sir A. N. EdelcrantZ; Richard Chenevix, Esq. F. R. S. and M. R. LA.; Mr. R. Winter; Mr. James Stodart; Mr. T. Jones; W. H. Woollaston, M. D. F. R. S.; J. M. Elliott; Mr. William Close; Mr. W. Jones, F. Am. P. S.; C.Wilkinson, Esq.; Mr. J. C. Hornblower ; Mr. J. J. Hawkins ; I. R. I. ; Mr. Sharpies; B. Of Foreign Works, J. H. Hassenfratz; Thenard; C. L. Cadet; J. B. De Roover; M. L.* Schnaubert; Professor Proust; Klaproth; Count de Bournon; Brugnatelli; Ritter; Benzenberg; S. P.; Bouvier; Wolff; Dyckhoff; J. B. Van den Sande ; Berthollet. Of English Works, abridged or extracted; Rev. Richard Yates, F. R. S. ; Mr. Tho. Willis ; John Playfair, F. R. S.; S. H. C. Englefield, Bart. F. R. S. ; William Herschel, t. L. t). F. R. S!; T. S. Dyot Bucknal, Esq. M. P. ; Ben- jamin Smith Barton, M. D. ; John Stockwell, Esq. ; Mr. John Cowie. Of Engravings the Subjects are, 1. Station Pointer for de- termining the precise Situation of a Ship or Vessel from two Horizontal Angles, by Joseph Huddart, Esq. F. R. S. 2. Mr. Dalton's Scheme for shewing the Distribution of the Particles in Mixed Gases. 3. Diagram to shew the Method «f constructing and computing the Situation of an Observer from ADVERTISEMENT. from the Angular Pofition of Three known Obje6ls. 4. Double Barrel and Winch for encreasing the Power without Diminution of Strength. 5. Screw Press, which by the contrary Action of Two Helical Threads, affords great In- crease of Power at the Place of moft extreme Pressure. 6. Pump acting by the Difference of Two Cylinders. 7. Al- phabetical System of Writing in the Dark, by Mr. John Gough. 8, 9. Two Plates, Apparatus for fupplying Worm- Tubs, &c. with Water, on the Syphon Principle; By Sir A. N. Edelcrantz. 10, 1 1. Construction of a fimple Repeater for the Hours and Quarters, By Mr. J. M . Elliot. 1 2 . Diagram to illustrate the Investigations of the Figure of the Earth> by Professor Playfair. 13. Improved Chemical Furnace, by R. Chenevix, Esq. F. R. S. 14. Figures to illustrate an Improvement ip Spectacles, by W. H. Wollaston, M. D.. F. R. S. 15. New Steam Digester, in which the Heat and Pressure are rendered stationary ; by Sir A. N. Edelcrantz. 16. Remarkable Strata of Flint, by Sir Henry Charles Engle- field, Bart. F. R. S. 17. Figure to illustrate Dr. Herschers Theory of the Changes in the Situation of Double Stars. 1 8, Mr. Hornblower*s Apparatus for fweeping Chimnies. 19. Figures to explain the Changes of Double Stars, by Dr. Herschel. 20. Galvanic Apparatus to afford the Maximuni of Effect in Combustion, by I. R. I. 21. Hydraulic Engine for raising Fresh Water, by the Discharge of Waste Water, by Mr, Sharpies. Soho Square, Jprii, 1804, TABLE OF CONTENTS TO THIS SEVENTH VOLUME, JANUARY, 1804. Engravings of the following Obje£ls: 1. The Station-Pointer of Jofeph Hadf dart, Efq. F. R. S. by which the Situation of a Ship or Veffel is very precilely determined from Two Horizontal Angles ; 2. A Scheme, by Mr. Dalton, for fliewing the Pjftribytion of the Particles of mixed Gafcsj 3. Diagram to fliew the Method of conftru6ling and computing the Situation of an Obferver from the angular Pofition of Three known Obje^s j 4. A double Barrel and Winch,, for increafing the Power without any Diminution of Strength ; 5. A Screw-" Prefs, which, by the contrary Aflion of Two Helical Threads, affords a sreat Increafe of Power at the Place of the moft extreme Preffure ; 6. A Pumpa^- ing by the Difference of Two Cylinders} 7. Alphabetic Syftem for writing in the Dark, by Mr. John Gdugh. I. Defcription and Ufe of the Station -Pointer; an Inftrument for readily af- certaining the Situation of the Obferver, after having determined the angular Pofition of Three known Objefts j coniiru6led by Jofeph Huddart, Efq. F. R. S. and communicated by him to the Editor. - - 1 JI. Experimental Effays on the Conftitution of mixed Gafes 5 on the Force of Steam or Vapour from Water and other Liquids in different Temperatures, both in a Torricellian Vacuum and in Air j on Evaporation j and on the Expanfton of Gafes by Heat. By John Dalton. - - - 5 in. Obfervaiions on the Cultivation and Growth of Oak Timber. In a Letter from the Rev. Richard Yates, F. A. S. Chaplam to his Majelty's Royal Hof- pital at Chelfea, to Charles Taylor, Elq. Secretary to the Society of Arts. 17 IV. A Firft Memoir on coloured Shadows. By Cit. J. H. HafTenfratz. 23 V. Account of the Preparation of the Hyacinthus non Scriptus, or commoa Blue-Bell, as a Subllitute for Gum- Arabic. In a Letter from Mr. Tho. Willis of Lime-Street, London, communicated to Charles Taylor, Efq. Secretary to the Society of Arts. - - - - 30 VI. A Memoir on Vinous Fermentation. By Cit. Thenard. - 33 VII. Conje6lures refpefting the Formation of the Ice in the Cavern of Grace Dieu. By C. L. Cadet, of the College of Pharmacy. - - 44 VIII. Obfervations on the Stru6ture of the Tongue j illuftrated by Cafes in which a Portion of that Organ has been removed by Ligature, By Everard Home, Efq. F, R. S. - - - - - - 47 IX. Account of Three Mechanical Stru6lures not commonly noticed or known, in which the Effc6l is produced by the Difference between the Aftions of Two fimple Inftruments of the fame Defcription j namely, 1. a compound Barrel and Winch; 2. a compound Screw; and 3. a compound Pump, W. N. 59 X. Scoteography, or the Art of Writing in the Dark. In a Xetter from Mr. John Gough. ------^53 XI. Method of uniting Sulphur and Phofphorus without Danger to the Ope- rator, and an. Attempt to explain the Change that then takes place. By Robert Briggs, M. D. Edinburgh. Communicated by the Author. 5^ XII. On the beft Method of afrertaining the Dip at Sea. In a Letter from Mr; Ezekiel Walker. -.-.-. 52 XIII. New Procefs for fabricating Alum artificially, and without the Afliftancc of Evaporation, By Cit. Curaudau, Correfponding Member of the Society of Apothecaries of Paris. ----- 63 XIV. Letter from Mr. John Farcy, concerning the great Fiery Meteor of No- vember 13, and on other Subje6ls. - . _ - (^5 XV. Method of reftoring rancid Effentlal Oils. By J. B. De Roover. 6$ XVI. Queftions, 1. refpefting the Place of the ere6l Image behind a Concave Speculum; 2. and of the Image formed by a Concavo-convex Mirror, which is not Left-handed, and has the Property of revolving on its Axis along with the Mirror, but twice as fall; and, 3. the Figure of the Sky. By a Correfpon- dent. -.--_--. 71 XVII. A New Method of preparing the pure Gallic Acid. 3y M. L. Schnau- bert, * • • • -• * ^ 74 Scientific ii CONTENTS. Scientific News, 75.— Reward of Twenty Pounds for the Artificial Produ6lfo« of Palladium, ib. — Letter from Lahmde on the Meafure of a Degree of the Earth in Lapland, 76. — Letter from Profeflor Proult to J. C.-Delanietherie on a dangerous fulminating Powder, 77. — Letter from a Correfpondent on the Expediency of converting Foreign Weights and Meafure s into Eng^lifli, ib. Account of New Books, 79. — A Syftem of Theoretic and Practical Chemiftryi in Two Volumes, with Plates. Bv Frederick Accum, if .—A pra6lical Effay 7 on the Analyfis of Minerals, ib. — A general Hiltory of Mathematics, from the ' , earlieft Times, to the Middle of the^Eighteenth Century, 80. FEBRUARY, 1804. Engravings of the following Objefls : 1, 2. Two Plates exhibiting the Means of completing the Apparatus for fupplying Worm-Tubs, Sec, with Water, on the Syphon Principle, by Sir A. N. Edelcrantz; 3, 4. Two Plates to ihew the Conftru6lion of a fimple Repeater for the Hours and Quarters, by the Inventor Mr. J. M. Elliot J 5. Diagram to illultrate the Inveftigations of the Figure of the Earth, by Profeflbr Playfair; 6. An improved Chemical Furnace, by R. Chenevix, Eiq. F. R. S. ; 7. Figures to illuftrate an Improvement in Spec- tacles, by W. H. Wollafton, M. D. F. R. S. I. Defcrlption of an Apparatus, by which the EfFe<5V of Atmofpheric Preflure In fupplying Worm-Tubs and other Veflels with Water on the Syphon Prin- ciple, may be fecured againft any Interruption to be caufed by the extricated Air. In a Letter from Srr A. N. Edelcrantz, Counfellor of the Chancery, and Private Secretary to the King of Sweden, Member of the Swedilh Academy, &c. &c. - . , - . Page 81 II. Enquiries concerning the Nature of a Metallic Subftance lately fold in London as a new Metal, under the Title of Palladium. By Richard Chenevix, Efq.F.R. S. andM.R.I.A. - - - - - 83 III. Invcftigation of certain Theorems relating to the Figure of the Earth. By John Playfair, F. R. S. Edin. and Profeffor of Mathematics in the Uni- verfity of Edinburgh. ------ 102 IV. On the Determination of the Length of the Solar Year. By Mr. R. Win- ter. - - - * - - -- 116 V. Extrafl from a Letter of R. Chenevix, Efq. F. R. S. from Drefden, to Charles Hatchett, Efq, F. R. S. containing Information refpefling the new Metal contained in Crude Platina j Beet Sugar j the Non-Exiftence of Aguf- tite as a peculiar Earth ; and a Defcription of a new Furnace for Chemical Operations. Communicated by C. Hatchett, Efq. '- - 117 -Vl. Account of an Experiment to imitate the Damafcus Sword Blades. In a Letter from Mr. James Stodart. - - - - 120 VII. Letter from a Correfpondent on the Effects of Thuader on fermenting Li- quids} the Chemical Aftion of Sound, and Tremulous Motions j with other Obfervations. - - - - - - 122 VIII. Improvement of the Electrical Machine, chiefly with Refpe6l to the Rubbers; by Mr. Wolff, of Hanover. - - - 124 IX. On the Cultivation of the Sun-flower, and its Advantages. 128 X. Chemical Examination of a new Vegetable Salt, and of a new Acid dif- coveredinit: by Klaproth. - - - - - 129 XI« On Mr. Woolf's Invention for equalizing the Aftlon of a Crank, m Contradiftlnflion to the Effe6l of the Fly, in producing an uniform Effeft againft a variable Refiftance. In a Letter from Mr. T. Jones. 133 XII. Obfervations on the extinft Volcanoes in the Environs of Coblentz, by the Chevalier de Sade. Tranflated from the original Manufcript, communi- cated by the Count de Bournon. - - - - 135 XIII. On an Improvement in the Form of Spe61:acle-Glaflres, by William Hyde Wollafton, M. D. F. R. S. Communicated by the Author. - 143 XIV. Letter of Enquiry concerning a Gun to throw double-headed Shot i with the Editor's Reply. - - - - - - 146 XV. Prognoftics of the Weather, eftablirtied by long-continued Obfervation upon the Conduft and Appearances of Birds, Beafts, Inltils, Plants, Meteors, the Heavenly Bodies, Minerals, &;c. Communicated by a Coireifondent, 148 XVI. A CONTENTS. iU XVI. A New, Cheap and Simple Apparatus for repeating tlie Hours and Quarters in Clocks aAd Watches. By Mr. J. M, Elliot. Communicated by the Inventor. --_>.- 157 Scjentific News, 159. — Prize for the artificial Compofition of Palladium. ib, Prize adjudged at the laft Public Meeting of the National Inftitute, ib.— Teyierian Society at Haarlemj 1 60. MARCH, 1804. Engravings of the following Objefts : 1. A new Steam DIgefter, In which the Heat and Preflure are rendered ftationary, by Sir A. N. Edelcrantz ; 2. A Pelign exhibiting fome remarkable Strata of Flint, by Sir Henry Charles Englefield, Bart. F. R. S. 3. A mercurial Air- Pump of unlimited cxhaufting Power, by Sir A. N. Edelcrantz ; 4. Sketch of the Occultation of a Fixed Star by the Planet Mars, obferved by Sir Henry Charles Englefield, Bart. F. R. S.J 5. Figure to illuftrate Dr. Herfcheirs Theory of the Changes in the Situation cf Double Stars. J. Defcription of a new Steam Digefter for Philofophlcal Refearches. By Sir A' N. Edelcrantz, Counfellor of the Chancery, and private Secretary to th« Kirg of Sweden i Member of the Swredi/h Academy, &c. &c. Communicated by the Author. - . - - _ 1^^ II. Inveft gation of certain Theorems relating to the Figure of the Earth. By- John Pjayfair, F. R. S. Edin. and Prof e (for of Mathematics in the Univerfity of iidinburgh' . - - - - - 167 III. Enquiries concerning the Nature of a Metallic Suhftance lately fold In Lon- don as a new Metal under the Title of Palladium. By R. Chenevix, Efq. 176 IV. Obfervations on fome remarkable Strata of Flint in a Chalk-Pit in the Ifle of Wight, in a Letter from Sir H, C. Englefield, Bart. F. R. S. to J. Latham, M..D. F. R. S. and L. S. - - - 183 V.Deicription of a mercurial Air-pump, of unlimited exhaufting power, with a Wooden Pi (Ion, wo'king in a Wooden Cylinder, &c. By- Sir A. N. Edel- crantz, &c. &c. Conmiunicated by the Author. - - 188 VI. O.n the Combinations for fupplying Worm Tubs with Cold Water, by the Syphon, with an caly Method of fecuririg the Joints of fuch Hydraulic Ap- paratus again ft the AdmifTion of the External Air. In a Letter from Mr. William Cloie. -. - - - - 191 Vlli An Anfwer to Dr. Wollafton's Statement, " Of an Improvement In the EoYfri, of Spedtacle-Glafles." By Mr. W. Jones, F. Am. P. S. Optician, . Holborn. - - - - . 192 VI II. An Account of an Occultation of b Nebulae Sagittaril, by the Planet • Mars, on the 17th of April 1796, obferved by Sir Henry Englefield, Bart. F. R. S. In a Letter addrelTed to the Rev. Ncvil Maikelyne, D. D. F. R. S. and Aftrononier Royal. - - - - 193 IX. Letter from Mr. Ezekiel Walker, containing a confiderable Improvement in Time-Pieces, by Mr. Berraud, with Remarks. - - 205 X. Letter from C. Wilkinfon, Efq. containing Fads upon which Deduftions are made to (liew the Law of Galvanifm in burning the Metals, according to the DifpolUion of equal Surfaces of charged Metallic Plate. . 2OS XI. Account of the Changes that have happened, during the laft Twenty-five Years, m the relative Situation of Double- ftars ; with an Inveftigation of the Caufe to which they are owing. By William Herfchel, LL. D. F. R. S. From the Philofophical Tranfadions for 1803. - - 210 Xn. On the Nature of the Varieties of Engrafted Fruit-Trees, with a Plan for increafing the Number of New valuable Fruits. By T. S. Dyot Buck- nal, Elq. M. P. " " . " . " " 227 Xin. Explanation of the Subje6>s concerning which Queftions were propofed at Page 71 of the prefent Volume} namely, 1. The place of the Ereft Image behind a Concave Speculum ; 2. Of the Image formed by a Concavo Convex Mirror, which is not Left-handed, and has the Property of re- volving along with the Mirror; and 3. The Figure of the Sky. By W. N. 236 Uieful Notices refpefting various Objefts. By a Correfpondent, 240.— Cotton in Inks ib«— Shaving with Water, ib, APRIL. W CONTENTS. APRIL, 1801.. Engravings of the following Objefts : 1. A new Apparatus for fweeplng Chim-. nies, communicated by ;he Inventor Mr. Hornblower; 2. Figures by Dr. Htrrfchcl, to explain the Changes of Double Stars j 3. A Galvanic Apparatus to atford the Maximum of EfFe6l in Combuftion, from I. R. I. a Coriefpon- dent J 4. Anew Hydraulic Engine, which, by the Difcharge of Wafte Water, raifes Freih Water to the Ap;a tments of a Houle, &c. by Mr. Sharpies. I. Experiments proving the Advantage of Perifcopic Spe(5kacles. Communi-' cated in a Letter from W. H. WoUafton, M.D. F. R. S. Page 241 II. Additional Obfervations on foOie remarkable Strata of Flint in the Ifle of Wight, in a Letter from Sir Charles Englefield, Bart. F. R. S. to John La- tham, M. D. F. R. S. and L. S. - - - 242 III. Account of a Machine for fweeplng Chimnies by a Blaft of Air. In a Let-< tcr from Mr. J. C. Hornblower, Engineer. - - 246 IV. Account of the Changes that have happened, during the laft Twenty-five Years, in the relative Situation of Double Stars j with an Inveftigation of the Caufe to which they are owing. By William Herfchel, LL. D. F. R. S. 252 V. Account of the Invention of the Compound Barrel and Winch, and its ufcful Application on a large Scale. In a Letter from Mr. J. J. Hawkins. 267 VI. Propofal for conltruding a Galvanic Apparatus of great Power, for the Combuftion of Metals. By a Correfpondent. I.R.I. - 269 VII. A Memoir concerning the Fafcinating Faculty which has been afcribed to the Rattle-Snake and other American Serpents. By Benjamin Smith Barton, M. D. - - - - - 270 VIII. Extra6l of a Letter from Brugnatelli on the Pruffiate of Potafli, and on the Preparation of a Fulminating Muriate of Silver. - 285 IX. Of the Application of Platina or Porcelain. By Klaproth. 286 X. Abftrafl of a Memoir on Galvanifm, fent to the National Inftitute by Mr. ]R.itter, of Jena. . - . - - 288 XI. On Speftacles, particularly the Perifcopic. In a Letter from Mr. E, Walker. . - - - - - £91 XII. Communication refpe6ling the Chay Root, a Species of Madder ufed for dying durable Red Colours in the Eaft Indies. By John Stockweli, Efq. 294 XIII. Delcription of an Apparatus for raifmg Water by the Fall of Wafte Water. By Mr. Sharpies, Portrait Painter, Bath. Communicated by the Author. - - - - - - 298 XIV. On Gridiron Pendulum Rods compofed of Lead and Iron. By Mr. Benzenberg. - - - - - 300 XV. On the Advantages of a large Knife in making Pens. By a Correfpondent. ib. XVI. Communication refpe6ling an Article fenr from the Eaft Indies, under the Name of Gum Kuteera, and of which a large Quantity has been lately imported into this Kingdom. By Mr* John Cowie. - - 301 XVII. Galvanic Experiments with Ice, and a Method of rendering the Eleftric Attra6lion of the Pile very evident. By S. P. Bouvier, of Jodoigne, Mem- ber of the Society of Emulation, of Natural Hiftory and Phyfics, at Bruf- lels. - - - - - - 30J; XV III. Experiments on the A6Vivity of a Galvanic Pile, in which thin Strata of Air are fubftituted inftead of the Wet Bodies. By Mr. Dyckhoff. 305 XIX. Extract from a Letter from Mr. J. B. Van den Sande, Profeflbr at Lux- embourg, on the Efflorefcence and Decompofition of Glals Tubes. 306 XX. On the Criterions or due Difcriminations of Cyder Fruit. By Thomas Skip Dyot Bucknall, Efq. - - - -.307 XXI. Concerning the Steam Engine from Mr. Blakey, by a Correfpondent. B. 310 XXII. Oblervationsand Conjmunications on the Dry Rot in Timber, made to the Society for Encouragement of Arts. - - - 315 Scientific News, 318. — Society of Agriculture, Commerce, and Arts, at Bou- logne-fur-Mer, ib. — Cryftallization of Lime by Tromldorlf, denied by Ber- thoUet, 319. — Converfion of Pieces of Cloth impregnated with a Solution of Salt into Soap of Wool, by the Action of the Galvanic Pile. By Brugnatelli, 320 i , • I ( I i • ill I • ' " If I ■' M'***!^ JOURNAL OF NATURAL PHILOSOPHY, CHEMISTRY, AND THE ARTS. JANUARY, 1804. ARTICLE I. befcrtption and life of, the Station Pointer ; an Injlnment.for^ readilj/ c{fcertaining the Situation of the Ohferver after luiving determined the angular Fofition of three known Obje^s; Con' T^rw^J^ec/f&y Joseph HuDDART, Efq. R R*S, and commu-, mcatcd hi/ him to the Editor, • * , 1 HAVE long been defirous of prefentlng my readers with inftrument for a drawing and account of the inftrument which forms the fub-^!^'"^-^ *l^ . " place from obff. je6l of the prefent paper. Its utility in protra6ling the fitu-of two angles ation of a veflel upon a chart from an accurate obfervation by of azimuth only* the fextant of the angular pofilion of three known dbje6ls on fhore, inftead of the uncertain and rough method of beariiigs by compafs, is great and obvious; and if any other' recommen- dation could be defired, it would be that of its repeated ap- plication in the hands of a man of fcience and experience.' This we have the fatisfadion to pdflfefs in the public labours of Mr. Huddart, whofe maritime furveys are too well known and efteemed to require the fuffrage of any individual at this day. The Very firft occalion, when I happened to have the pleafure of converfing with him, I requefled the cortimuni- cation of this inftrument, with which he with great readinefs favouredme, and from which the drawing exhibited in P/argave|, 8ic. Having previoufly to thefe experiments determined the force of aqueous vapour at all the temperatures under 21 2*^, I was naturally led to examine whether tlie quantity of water eva-r porated in a given time bore any proportion to the^force of va- — in every part pour of the fame temperature, and was agreeably farprifed to of the fcaiepro- ^„^ ^l^^^. ^|j^ exaaiv correfponded in every part of the therr portional to the -^ -^ , force of vapour mometric fcale ; thus the forces of vapour at 21 2*^, 180^, 164°, at that temper- 1.52°, M4^, and 138° are equal to 30, 15, 10, 7|, 6 and 5 inches of mercury refpec^ively, and the grains of water eva- porated per minute in Ihofe temperatures were 30, 15, 10, 7f , 6 and 5 alio; or numbers proportional to thefe. Indeed it fliould be fo from the elj-abliflied law of mechanics, that all effects are proportional to the caufes producing them. The atmofphere, it fliould feem, obftruds the diffufion of vapour, which would otherwife be almoft inftantaneous, as in vacuo; but this obllrudion is overcome in proportion to the force of the vapour. The obftrudlion however cannot arife from the zveight of the atmofphere, as has till now been fuppofed; for then it would efFcdually prevent any vapour from arifing un- der 212^ : but it is caufed by the vis inerlitz of the particles of air; and is fimilar to that which a ftrcam of water meets with in defcendingamongft pebbles. In low temper- The theory of evaporation being thus manifefted from ex- atures the eva- periments in high temperatures, I found that if it was to be force of vapour verified by experiments in low temperatures, regard raufl be at the temper- had to the force of vapour actually exifting in the atmofphere water diminiflied ^^ *^® i\v^Q. For inftance, if water of 39<* were the fubjed, by thatexifting the force of vapour of that temperature is ^ of the force at 'h-rcV^'"^^" 212^, and one might exped the quantity of evaporation -5'^ alfo; but if it fliould happen, as it fometimes does in fummfer, that an aqueous atmofphere to that amount does already exift, the evaporation, inllead of being -^-^ of that from boiling water, would would be nothing at all. On the other hand, if l»he aqueous at^iofphere were leis than that, fuppofe half of it, correfpond- ing to 39° of heat, then the elfedive evaporating force would ^^ TTS of that from boiling water; in fliorf, the evaporating force niijft be univerfally equal to that of the temperature of the water, diminiflied by that already exifting in the atmof- phere. In order to find the force of the aqueous atmofphere Experiment ta I ufiiaHy take a tall cylindrical glafs jar, dry on the oulfide, ^^^^^^"^^"^j^'J^^^ and fill it with cold fpring water frefti from the well; if dew mofpherk )be immediately formed on the outfide, I pour the water out, "^^P^"'''' let it ftand a while to increafe in heat, dry the outfide of the glafs well with a linen cloth, and then pour the water in again ; this operation is to be continued till dew ceafes to be formed, and then the temperature of the waterrauftbeobferved; andop- pofite to it in the table (p, 264, Vol. VI.) will be found the force It is the fame as of vapour in the atmofphere. This muft be done in the open ^^^' of water, ' . ^ . , * which js at che ajir, or at a window ; becaufe the air within is generally more loweft temper- humid than that without. Sprinoj water is generally about *^"'^' which r. 1 -n ri r t /• i i i /-, coadenfes no ^0°, and will moltly anlwer the purpole the three hotteit dew on its canr pionths in the year: in other feafons an artificial cold mixture taiaing veffeU is require^-. — The accuracy of the refult obtained this way I think fcarcely needs to be infifted upon, Glafs, and all other hard fmooth fubflances I have tried, when cooled to a degree below vyhat the furrounding aqueous vapour can fupport, caufe it to be condenfed on their furfaces into water. The degree of cold h ufually from 1 to 10^ below the mean heat oF the 24' hours ; in fummer I have often obferved the point as high as 58° or 59°, correfponding to half an inch of mercury in force, and once or twice have feen it at 62° : in changeable and windy weather it is liable to confiderable fluduation ; but this is not the place to enlarge upon it. For the purpofeof obferving the evaporation in atmofpheric Narrative of temperatures I got two light tin veflfels, the one fix inches in ^^^ expcnrnents '^ ° -■ .... .or evaporation diameter, and half an inch deep, the other eight inches dia- in atmofpheric meter and ^ inch deep; and made to be fufpended from a *®™P"*'"'""» balance, like the former one. When any experiment defigned as a tefl of the theory was made, a quantity of water was put into one of thefe (generally the fix inch one, which I preferred) the whole was weighed to a grain ; then it was placed in an open window or other expofed fituation for ten or fifteen mi- / nutes^ and again weighed to afcertain the lofsby evaporation ; at JO ON EVAPORATION^. at the fame time the temperature of the water was obferved, the force of the aqueous atmofphere afcertained as above, and the ftrength of the current of air noticed* From a great va- riety of experiments made both in the winter and fummer, and when the evaporating force was ftrong and weak, I have found the refults, entirely conformable with the above theory. The fame quantity is evaporated with the fame evaporating force thus determined, whatever be the temperature of the air, as near as can be judged ; but with the fame evaporating force^ a ftrong wind will double the effedt produced in a ftill atmofphere. Thus, if the aqueous atmofphere be correfpond- ent to 40*^ of temperature and the air be 60°, the evaporation is the fame as if the aqueous atmofphere were at 60° of tem- perature and the air 72* ; and in a calm air the evaporation from a velTel of fix inches in diameter in fuch circumftances would be about .9 of a grain per minute, and about 1.8 grains per minute in a very ftrong wind; the different intermediate quantities being regulated folely by the force of the wind. Account of the The following table exhibits the ratios and quantity of water *at»o^ ^**^°' evaporated in each temperature, derived from the preceding theory, and confirmed by experiments, as far as they have been extended. The firft column exprefles the temperature; the fecond, the correfponding force of vapour taken from the preceding table; the other three columns give the number of grains of water that would be evaporated from a furface of fix inches in diameter in the refpedlive temperatures, on the fup# polition of there being previoufly no aqueous vapour in the at- mofphere. Thefe columns prefent the extremes and the mean of evaporation, likely to be noticed, or nearly fuch: for, the (irft is calculated upon the fuppofition of 3.5 grains lofs per mimite from the veflfel of .3| inches in diameter; the fecond, 46 and the third 55 grains per minute. TABLE ON EVAPORATlOlf. II TABLE Shewing the force of vapour, and the full evaporating force of Table of the every degree of temperature from 20° to 85°, exprelTed ^"^^f J^^^^^^^^^ in grains of water that would be raifed per minute from a per minute at veffel of fix inches in diameter, fuppofing there were no b'^'J^een ao" vapour already in the atmofphere. and 85<^. Force of Vap. inch. 30 .129 .134. .139 .144. .150 .156 .162 .168 .174 .180 .186 .193 .200 .207 .214 .221 .229 .237 .245 .254 .263 .273 .283 .294 .305 .316 .327 .339 .351 .363 .375 .388 .401 .415 .429 .443 .458 .474 Evaporating Force in Grains, 120 154 189 .52 .54 ,56 .58 .60 .62 ,65 .67 .70 .72 .74 .77 .80 .83 .86 .90 .92 .95 .98 1. 02 1. 05 1. 09 1. 13 1. 18 1. 22 1. 26 1. 31 1. 36 1. 40 1. 45 1. 50 1. 55 1. 60 I, 66 1. 71 1. 77 1. 83 1. 90 .67 .69 .71 .73 .77 .79 .82 .86 .90 .93 .95 .99 1. 03 1. 07 1. 11 1. 14 1. 18 1. 22 1. 26 1. 31 1. 35 1. 40 1. 45 1. 51 I. 57 1. 62 1. 68 1. 75 1. 80 1. 86 1. 92 1. 99 2. 06 2. 13 2. 20 2. 28 2. 35 2. 43 .82 .85 .88 .91 .94 .97 I. 02 1. 05 1. 10 1. 13 1. 17 1. 21 1. 26 I. 30 1. S5 1. 39 1. 45 1. 49 1. 54 1. 60 1. 65 1. 71 I. 78 1. 85 1. 92 1. 99 2. 06 2. 13 2. 20 2. 28 2. 36 2. 44 2. 51 2. 61 2. 69 2. 78 2. 83 2. 98 12 Tabic of the quantities of y/atcr evaporated ^r minute at temperatures between 20? and ^5?. O;; EVAPORATJOK^. Tabic conlimicd. Temper- aturf. Force of Van. ^nch. Evaporating Force m Grains. 212^ 30 120 154 189 58" .490 I. 96 2. 52 3. 08 59 .507 2. 03 2. 61 3. 19 60 .524 2. 10 2. 70 3. 30 61 .542 2. 17 2. 79 3. 41 62 .560 2. 24 2. 88 3. 52 63 .578 2. 31 2. 97 3. 63 64. .597 2. 39 3. 07 3. 76 65 .616 2. 46 3. 16 3. 87 66 .635 2. 54 3. 27 3. 99 67 ,655 2. 62 3. 37 4. 12 68 .67$ 2. 70 3. 47 4. 24 69 .698 2. 79 3. 59 4. 38 70 .721 2. 88 3. 70 4. 53 71 .745 ?. 98 3. 83 4. 68 72 .770 3. 08 3, 96 4. 84 73 .796 3. 18 4. 09 5. 06 74, .823 3. 29 4. 23 5. 17 75 .851 3. 40 4. 37 5. 34 76 .880 3. 52 4. 52 5. 53," • 77 .910 3. 65 4. 68 5. 72 78 .940 3. 76 4. 83 5. 91 79 .971 3. 88 4. 9^ 6. 10 80 I. 00 4. 00 ■ 5. 14 6. 29 81 1. 04 4. 16 5. 35 6. 54 82 1. 07 4. 28 5. 50 6. 73 8.3 1. 10 4. 40 5. 66 6. 91 ^4 1. 14 4.. 56 5. 86 7. 17 85 I. 17 4. 68 6. 07 7. 4^ V(t of the table The ufe of tliis table will appear from the following pro- familiarly il- blems I luftratedt PROBLEM I. Haying given the temperature at which the aqueous atmof- phere begins to be condenfed into water, and the temperature of the air, to find the quantity of water that would be evapo- rated in a minute from a velTel of fix inches diameter. Solution. Subtra6l the grains oppofite to the lower temper- ature from thofe oppofite to the higher one, in the firft, fecond or third column of grains, accprdjng to the ftrength of the wind, and the remainder will be the quantity evaporated in a minute under thofe circumftances, nearly. Example^ 0!^ EVAPORATION. J^f P:x(imple. Let the point of condenfation be 52^, the tera-Ufe of the table perature of the air 65^, with a moderate breeze. fuftrited! *'" The number oppofite ,52° in the fecond column of grains is 2.06, and that oppofite 61)*^h 3A6; the difference, 1.1 grain, is thfe evaporation per minute. PROBLEM ir. Having given the quantity evaporated in a minute, found by experiment, and the temperature of the air, to find the force of the aqueous atmofphere, and the point of condenfation^ Solution. Subtra6l the obferyed evaporation from that op- pofite the given temperature in the table; and look above for the number neareft to the remainder in the fame column of evaporation, oppolite to which will be found the force of the aqueous atmofphere, and the point at which it begins to be eondenfed. Example. Finding the evaporation from a veffel of fix inches in diameter to be 1. 7 grain per minute with a brilk wind, air 62° ; what is the weight of the aqueous atmofphere, and the temperature at which it begins to be eondenfed into water.'' The number oppofiie 62° in the third column of grains is S..52, being the whole evaporating force at that temperature in a perfediy dry atmofphere; from which take. 1.7 grains^ ' the real evaporating force obfeived, and the remainidery 1.82, correfponds, as per table, to the force .294" inches of mercury, the weight of vapour, and to 43° of temperature.* Evaporutlon of Spirits, Etha\ S,'C. If the law of evaporation above given apply to water in ExperlTnents every part of the fcale of heat, no reafonable doubt can be ^^'^^^ ^^^w tfiat -^ '. , ' ^ , the evaporation entertained refpefting its application to other liquids. I have of fphits, ether, notwitlifiandin^ made feveral experiments on others, the re- ?^* ^p^'^^^^* fults of which are conformable to the fame law. Some of them water, follow : — * It may be proper to remind the reader that all the experiments on evaporation are underftood to be made in the open air, or in a window with a current inward ; alfo it may be obferved the evapo- ration in a ciofe room is much lefs and is beCdes irregular, being greater proportionably from a lefs furface, evidently from the ftag-. nation of the air. ] . Spirit 14* ON EVAPORATION. ExperimentB I. Spirit of wine. — Evaporated from a furface of four inches Jhc'eva^o^rTt^n' *" diameter, 54 grains in 25 minutes: air 53**; aqueous at- of fpirits, ether, mofphere at 49°, and beginningto rain with a moderate breeze. &c. follow the ii would proportionally have been 121 grains from a veflel of fame law as r • u • j- . -tl- • i r water. "^ mches in diameter. This gives nearly five grains per mi- nute. The fame fpirit boiled at or near 180*. Now from the data, water of 83° is equivalent in force to fpirits of 53°; and it may be feen that the evaporating force of water of 83° is nearly 5 in the firft and fecond columns of grain* of the table. It feems probable that the aqueous atmofphere does not diminilh the evaporation of fpirits as it does that of water. 2. Ether. — 1 . Put a phial containing ether, and a fmall tin veflel of If inch diameter into a fcale and balanced them ex- a6lfy : then poured the ether into the evaporating veflel and put the phial into the fcale again ; took out 40 grains from the op- pofite fcale, and waited till the equilibrium was reftored: this was in 8 minutes 6feconds. The air was 50°, and the ethef at firft 50*^; but it rapidly funk, as was found by dipping a very fmall bulbed thermometer into it, to 28°. In a window with 3 moderate breeze. . 2 and 3. Repeated the experiment in the fame circumftances, except the evaporating veffel, which was now porcelain, and 2j inches diameter. Loft 40 grains in 3 mi- nutes. Thermometer funk from 50 to 30°. The two expe- riments made this way did not difl^r above one or two grains. Thefe refults reduced to a vefl!el of 3| inches in diameter give ift. Experiment, lofs 17 grains per minute; 2 & 3 — 22f ■ The reafon why the refult in the firft experiment was fome- thing lefs than in the other two, was evidently owing to the circumftance of its longer duration, by which the ether was the greater part of the time in a low temperature, and confe- quently evaporated lefs. The ether ufed boiled at 102®. At 50° it was therefore in the capacity of water at 160°. But water at 160**, at moft lofesonly 17 or 18 grains per minute, and lefs 20** below that temperature. At firft view therefore it ftiould feem that ether evaporates quicker than the general law afligns. But it muft be allowed that the temperature of the air has fojue effect upon evaporation^ though it has certainly very ON EYAJPORATION^ 15 very little. Now ether in the above experiments is a6led upon by a current of air of an equal or higher temperature than it- felf; but water of 1 60*» is ufually aded upon by air 100^ lower than itfelf, which is every moment precipitating the vapour formed, and thus obftruding its circulation. This appears to be a fufficient caufe for the fmall difference obferved. With refpefl to mercury, fulphuric acid, muriate of lime. Evaporation of &c. there can be no doubt but they experience a real evapo- '""^^'^'^y* *<^' ifation like thofe above; but it muft be very fmall in proportion as their boiling points are high. And it would be difficult to make experiments upon fuch of thefe as have an affinity for aqueous vapour; becaufe their acquiiitlon from the aqueous at- mofphere would far exceed their lofs by evaporation. Since writing the above cflay, opportunities have occurred J^^ evaporation to afcertain whether the evaporation from ice is conformable to with the pr«cc- the fame law as that from water. Every one, who has tried ^'"S ^^* the experiment, admits the faft that ice is evaporable. I have lately made feveral obfervations on this fubje<5l, the refults of which, as far as they go, fupport the conclufion that the ge- neral law of evaporation continues the fame below the point of congelation as above it. All the experiments were made in the tin veflel above defcribed of fix inches in diameter; a quantity of water was fuffered to freeze in it, fo as to form a circular cake of ice; the veflel and ice were then weighed to- gether, and expofed in the open air for a certain time, after, which being again weighed, the lofs was found ; the force of the aqueous atmofphere was foraetimes determined during the experiment by a mixture of pounded ice and fait, in the man- ner already defcribed. Grs. H. Grs. Wind. Air. J»Iov. 5. In the night loft 110 In 9 j or, .20 per m. N. E. briik. »8 Experimental — at 10 A. M. — . 25 in il; or, .33 N. E. mod. 31° refults. —•29. at 1 P. M. — 24 in i|i or, .23 calm. 31** P. M. — 84 in 9I; or, ,15 — — 30* —30. In the night — 94 in 9 j or, .77 — — N. E, mod. 31' Dec. 19. P. M. — 75 in 8 $ or, .16 N. E. calm. 26** —28' In the night — 33 in ii j or, »05 — — < calm. 29* ' •—20. A. M. — 21 in 2 J or, .175 — — W. mod 31* Some of thefe being made in the night, and of long duras tion, neither the temperature of the air, nor the force of the aqueous atmofpheie could be fairly determined : the fecond experiment hygromerer. experiment was made under every favourable circumHance^ and the aqueous atmofphere found at 22**. By problem li, at page 13, it would have been determined at2l|°, ufing the fecond column of grains in the table. On the fubjeft of evaporation it may be confidered as un- pardonable not to advert to De Sauflure's valuable Eflays on Hygrometry. Experlmenrsof That excellent philofopher determined, by a well conceived wnf are^"with experiment, that dry air of the temperature of 64° or GG'', the preceding iinbibcd aqueous vapour fo as to increafe its elafticity -^ of the theory. atmofpheric prefTure; and that a cubic foot of fuch air required II or 12 grains of water to produce the effect. By the table above at page 12 it appears the force of vapour at 61°=. 54* = -yL. of 29 .5 inches nearly. It is probable this difference is occafioned in part at leaft by the want of perfe6l drynefs in the air he operated upon, which caufed the increafe of elaffi- He confided too city to be lefs than otherwife. It was, t think, unfortunate much in is ^^^^ j^^ attached (d much importance to and confidence in his i)ygrometer; and that he adopted the theory of chymical folu- tion of water in air, contrary to the fads he difcovered, which feemed more reconcileable to the notion of aqueous vapour be- ing a diftinct elaflic fiuid. Indeed he is forced to acknowledge in the ift. chap, of his Eflay on the Theory of Evaporation, that in the ordinary temperature of the atmofphere, aqueous vapoiir is formed in the firft inftance a diflant elaftic fluid, and after it has been converted into an elafiic fluid, it is diffolved by the air; " Je crois qu'il ne la diffout que lorfque I'acftion du " feu I'a convertie en vapeur elaftlque.'* Now if it can for a moment exift independently under the preffure of the atmof- phere, why may it not contmue to exift in that ftate? and on that ac- J-Jis table of the weight of aqueous vapour in a cubic foot of air at different degrees of the thermometer, being derived from experiments with his hygrometer, except the ftandard one of 66° [Ij^'Reaumur), is far from accurate; and the in- accuracy increafes with the diflance from the ftandard, whicb, as has Ix^en obferved, appears to be nearly corre6l : in the "higher temperatures he makes the water diffolved too little, and in the lower temperatures too much. He fays (§ 93) that the loweft he has feen the hygrometer in the open air, is 40; and tliat it indicated a reduction of temperature in the air amounting 3 count his tables are inaccurate. Cultivation of oaks. l7 amounting to 34° .7 (78° of Fahr.) was necefTary In order to depoiit dew. This obfervation alone is fufficient to render his hj'grometer fufpeded; for, few who have attended to the formation of dew will admit the probabilityoffo large a reduc- tion being neceffary in any climate or feafon : I believe it rarely requires 40° reduction in temperature in any part of the world to produce the effed. Plate I.* is intended to illuftrate the author^s conception of Engraving to the conftitution of the atmofphere. The different marks or JJj^j^ the conftl- characters of the particles of the gafes are merely arbitrary, atmofphere. and intended for diftinflion; the fimple atmofpheres are given nearly on their real dentities, and the particles are arranged at i equal diftances from each other. In the compound atmof- phere the fame arrangement is made of each kind of particles as in the fimple; but the particles of different kinds do not arrange at regular diftances from each other; becaufe it is fup- pofed they do not repel each other. . III. Obfervalions on the Cultivation and Growth of Oak Timber, In a Letter from the Rev. Richard Yates, F. A. S. Chaplain to His Majefiy^s Royal Hofpital at Chelfea, to Charles Taylor, E/q. Secretary to the Society of Arts \. S I R, JL O expatiate upon the vaft importance of increafing the Great Impor- growth of oak-timber, feems unneceffary. The national ad- [u"e^of^the oak! vantages refulting from this fource appear to be in general well underftood ; and yet the cultivation and management of this moft ufeful plant has not hitherto obtained jtbat degree of ^ attention which it moft certainly merits. Entirely to obviate, or even in fome meafure to remove or leffen, the obftacles that ftill continue to impede the planting * From the fame Vol. of the Manchefter Memoirs.— I remind the reader of the references at page 257 of our laft, t For which the filver medal was voted. Memoirs for 1802, page 80. Vol, VII.— January, 1804. C of Jg CULTIVATION OF OAKS. of oaks, would therefore be rendering an eflential fervlce to the nation. The defire of accomplifliing fo beneficial a pur- pofe, has induced the judicious and public-fpirited conduftors of the Society of Arts to propofe a premium for " afcertaining •' the beft method of raiiing oaks :" — in confequence of which, this paper is fubmitted to their candid confideration. And as tke ftatements here made are founded upon a fedulous and active experience of fifty years, it is prefumed the ffnrit and 7rieanirig of the Society's propofal may have been obferved, although it has not been poffible (in this inftance) literally to fulfil its terms ; at leaft, the very intention of promoting and forwarding the views of fo enlightened and highly ufeful a Society, may, it is hoped, be accepted as an apology for calling their attention to thefe obfervations. Cultivation of Jt forms no part of the prefent defign to enter minutely ya,,g^ " into the various caufes that continue to operate in obflruding the cultivation of oak ; as there is one of peculiar magnitude, the confequences of which are highly detrimental and inju- rious, and which it is therefore the principal objed of this paper to remove, from a notion of ^^ opinion is generally prevalent, that the oak is particu- growt^ ° ^^^^y ^^^ "^ ^^^ growth, and requires a great number of years before it aflfbrds any advantage. This idea too often deters from planting, on account of the very great length of time it is fuppofed the land muH be occupied before any return of valuable produce can be obtained from it, after a confiderable expence may have been incurred in forming plantations, whichisamif- This opinion I confider as entirely founded in error, and to have taken its rife in a great meafure from the want of pro- per management that has hitherto commonly prevailed in the raifing of oaks : and in this paper I ftiall endeavour ftrongly to ftate, that the oak may be rendered very rapid in its growth, and that confequently land may be employed to great advan- tage in its cultivation, as a very confiderable and profitable ' produce may, in a much (horter time than is generally fup- pofed, be derived from proper parts of an eftate thus employed. Oaks are fufFer- Qak-timber in this country, for the moft part, appears in (flowiy) with a trees of a confiderable extent of head, but feldom more than ihortftemand tn;enti/ or iltirty feet in flem ; and this, in many inftances, the their Ji»e may be ^^owth of a Century. Now, by the courfe of management here CULTIVATION ©F OAKS. 1^ hera propofed^ it is conceived that trees, of at leaft double doubled m half M/« mtfg;«7MC?tf, may be obtained in about half that time. -' It is not ray intention to attempt a proof of this propofition by theoretical deductions, but to appeal for its confirmation to the indubitable teft of fad, which, from the event of repeated trials, imprefles a convi6lion, that experience will be found to fupport and eftablifli it in the moft unequivocal manner. It would be eafy to enlarge much on the various qualities of foil, the nature and procefs of vegetation, and the peculiar properties of the oak ; but as thefe topics may be found amply and judicioufly difcufled in many other authors, who have ex- prefsly treated on thefe fubjeds, I fliall decline all fuch fpe- culations: and, with the hope of being more eflentially ufeful, lliall confine myfelf to a ftatement as fimple and practical as poffible. The oak, in the progrefs of its growth, fpreads numerous It is of the ut- roots near the furface of the ground, and in an horizontal di- "J^^ jmportance o ' _ ^ that the perpea- reftion : thefe affift in fupporting and preferving the tree in its dicular or tap pofition, but feem to contribute very little to its increafe and J'^^^^^ P"^^" magnitude. The oak appears to derive its chief nutriment and ftrength from a root that always defcends at right angles to the horizon, and is called the tap-root. The firft thing, therefore, to beobferved is, that upon a judicious attention to this pecu- liarity, the planter's fuccefs principally depends; and the negled of this care is the conftant fource of error and difap- pointment. In all climates, and upon all foils, to preferve this tap-root from injury, and as much as poffible to affift its growth, is a general, and indeed the moft eflential principle in the cultivation of oak. With a due regard to this circum- ftance, the management of a plantation may be refolved into the three following pra6lical dire6lions : Premoiijly to planting the acorns, loofen the earth intended Inftruftlons f<» for their reception, by deep trenching, ^roujid"^ d^ Never travjplant, or in any way difturb, the faplings in- planting acorns, tended for timber. Keep the plant carefully pruned, till arrived at a proper height. More fully to elucidate the fubjed, and to prevent the pof- fibility of mifapprehenfion, it may be proper to give a more detailed ftatement, C 2 In on CULTIVATION OF OAKS. Oaks fof timber In determining on a fpot to form a plantation of oaks for arc never to i>c jj^ber, it muft always be recolleaed that the plants are to remain without removal in their firft fituation : the clearing and fencing may then be attended to as ufual ; and in the courfe of the winter, from September to March, the particular fpots intended for the reception of acorns, may be prepared for that purpofe, by digging a trench about three feet in width, and from three to iSx feet in depth, according to the clofenefs and tenacity of the foil. If grafs-ground, the firft fpit fliould be placed at the bottom of the trench ; and if more than one trench be neceflTary, they fliould be prepared in the fame manner, preferving a diftance of ten yards between each, if it be intended to employ the intermediate fpace in underwood, or for any other purpofe. Having made a careful feledion of acorns that are perfectly found, and in good prefervation, they are to be planted about the middle of March. Draw a drill in the centre of the trench ; two inches in depth, if the foil be heavy and loamy ; but three inches in a light and fandy earth. In this place the acorns two inches afunder, and cover them carefully with mould. When the plants appear, they muft be weeded by hand in the rows, and the earth of the trench round them cleaned with a hoe, once a month during the fummer. In October infped the rows, and thin them by pulling up every other plant : attention will of courfe be paid to remove the weak and crooked plants, and leave thofe that are talleft and ftraiteft. On the fecond year, the operation of thinning muft be repeated, at the fame time, and in the fame manner ; and, fliould any of the remaining plants have made lide-flioots ftrongerthan the general charac- ter, they muft be fmoothly cut off with a fliarp knife, clofe to the leading ftem. On the third year, the thinning is again to be repeated, and the general pruning commenced, by cut- ting off clofe to the leading ftem all the fide-fhoots of the firft year ; thus leaving the branches of two years to form the head of the following year. The removal of every alternate plant muft be continued yearly, till the trees are about thirty feet apart, at which diftance they may remain for timber. The pruning is to be continued, by removing every year, very fmooth and clofe to the main ftem, one year's growth of fide branches, till the plants are arrived at a ftem of forty, fifty. or CULTIVATION OF OAKS. 21 ' or fixty feet, and they may then be permitted to run to head J"{^[;^^°"'i^' without further pruning. oak. » The particular arrangement here recommended may be varied according to any pecuHarities of fituation, regard being conflantly had to the general and moft important principle of loofening the ground rery deep previoufly to planting the acorns. By this mode of culture, oaks may be raifed in almoft any foil; but, where it is poflible, a loam or marl is always to be chofen. Oaks thrive much the beft in fuch earth ; and, when affi fled by deep trenching and judicious pruning, attain in a few years to an immenfe fize. Thofe who have been accuftomed to notice the flow growth and ftunted appearance of oak trees, when denied the affiftance of art, and left to themfelves in the common way, would obfervu with aftonifliment the vigorous and rapid increafe of plants under the management now pointed out. The plants thinned out the firft three or four years, though not fit to be depended upon for timber, as tranfplanting ge- nerally injures very materially the future growth, may be re- • planted in the intermediate fpaces between the rows, for the purpofe of being afterwards removed ; or they may be ufefully placed in hedges, or other fpare and unoccupied fpots of ground. They fliould be headed down at the time of tranf- planting, as this operation affifts the procefs of nature, in reproducing or remedying any injury the tap-root may have received from the removal ; and, if proper attention be given to loofening the foil for their reception, and pruning them as they advance, in moft jnftances an adequate profit will be derived from the labour beft owed upon them. After a few years, the produce of the timber-plantation will be found very- advantageous. The young trees that are to be removed yearly, will always find a ready market for a variety of pur- pofes unnece{rary''here to enumerate. In addition to thefe advantages, if by this treatment of deep trenching previous to planting, and annual careful pruning during the growth, timber can be produced in about fifty years, of equal quality, and much fuperior in fize, to that which has been above one hundred years growing under improper management, or with- out the affiftance of cultivation; it will doubtlefs be allowed that a moft beneficial, if not abfolutely the beft poflible method of <* raiflng oaks,'' is here pointed out and afcertained. 22 CULTIVATION OF OAKS. Inftruaions for Xhis method of cultivation may perhaps be thought to occa- ^ly^ fjon fo much expenfe in manual labour as to prevent its being generally adopted : it might perhaps be fufficient to obferve, that if the work be conduced with judgment and economy, the future produce would afford ample returns for all neceflary expenditure : it rtiould alfo be recoUedled, that the previous preparation of the ground, and the fubfequent pruning of the plants, are both to be performed at that feafon of the year when a fcarcity of work will enable the planter to obtain af- fiftance upon ealier terms ; with this additional advantage alTo, of providing employment for the labourer at thofe times when the general flate of agricultural bufinefs renders it dif- ficult for him to find maintenance for himfelf and family with- out charitable relief. In 17jO, at Ingeflrle in StafTordfliire, the feat of Lord Chetwynd, fome plantations were formed and managed in a, great meafure according to the principles here flated, and the' growth of the plants were fo uncommonly rapid, and fo ex- traordinary, that it could not but attradl the notice of all con- cerned in the condud of them. The attention to the fubje6l, then excited, has been the occafion and ground of all the obfervations and experiments made from that time to the pre- fent, the refult of which is given in this paper. The extenfive plantations of the late Lord Denbigh, at Newnham Paddox, in Warwickfhire, are well known and much admired. The whole has been condu6led with great judgment. About a fquare acre has been employed in raifing oaks upon a plan nearly limilar to that now propofed, and aflt^rds the befl and mofl convincing proof of the fuperior utility and efficacy of fuch management. Had the Roble Earl been now living, 1 fhould have been enabled to have laid before the Society fome more detailed particulars ; That, however, is now impoffible ; this paper, therefore, in its prefent ftate, may perhaps be thought not altogether unworthy of notice, as tending to forward the liberal deligns of the Society, and con- tributing to the advantage of the public, the author conceiving that the befl method of raifing oaks is afcertained and flated in it. Should the Society be in any degree inclined to join in this fentiment, it may perhaps induce them to make fome alteration in tlie terms of their propofal ; as, according to the ftatements made MEMOIR ON COLOURED SHADOWS. 23 made in this paper, and indeed from what may be feen in Jnftru£lions fot every part of the kingdom, in the charader and appearance <="'^ivating the of oaks growing without cultivation, itfeems afcertained, that ** acorns fet with the fpade or dibble, without digging or '' tillage," can never be depended on to form good timber ; and even in the moft favourable circumftances of this cafe, the growth will be exceedingly flow and precarious. The fame may be faid of " young plants, previoufly raifed in nurferies, " and tranfplanted ;" for if the tap-root be cut, broken, or in any degree injured, which in tranfplanting it is almoft im- poffible to avoid, that plant will feldom become a vigorous and flouriQiing tree. To form a courfe of experiments on fuch a plant as the oak, is not a^'cry eafy matter. To fulfil expli- citly the conditions of the Society would require a great length of time, and would be attended with confiderable expenfe, from which future candidates may in a great meafure be exo- nerated. Theraifing even one acre in the manner here afcer- tained might be prod u dive of great pecuniary advantage, if the fafts and experience detailed in this paper are permitted to prove the inutility of the other two methods, and confe- quently to remove the neceffity of employing fo much ground upon them, at an expenfe they will never repay, Chelfea College, Nov. 4f, 1801. IV. A Firjl Memoir on coloured Shadows, ByCit. J. H. Hassenfratz. (Concluded from Vol. VI, page 285.; PART THE SECOND. JL HOUGH the (hadow produced by the concurrence of the shadows pro- folar light with that of theatmofphere, ufually prefents only that ^^^^Z lights, feries of colours contained in the portion of the fpe6lrum, arc more various between green and violet, it is not the fame with the co- j^gj^^^^fg^^e^ loured thadows obferved in the interior of rooms, when fe- f^re defcribed. veral lights dire6l or refleded concur with that of the at- raofphere to enlighten the plane on which the fhadow is obferved OA MEMOIR ON COLOURED SHADOWS. obferved ; thefe are capable of Aiewing all the colours of the prifm ; in fad, we fee red, orange, yellow, green, blue, indigo and violet, more or lefs blackened. Number of The number of thefe thadows is almoft always two or three, ihadows. fometimes four or five; it has even happened that we have didingu idled fix. When thefe fhadows are two in number, the colours they prefent are always thofe called complemmtary colours. Combination of The infinite variety' of colours obferved in the folar fpec- tTtrthe follT' ^'■""^ *"^y ^® imperfeaiy imitated by combining different pro- fpeftrum. portions of the natural colours, red, yellow and blue ; and, according to the obfervations of Newton, an artificial white may be formed, by mixing thefe^three colours. Tjpofe co- Complementary lours are denominated complementary, which muft be made colours. ^jj^j^ one or two of the tiiree colours cited, to produce an ar- tificial white with a given colour. To obtain an artificial white with a red, the yellow and blue muft be mixed with it. The yellow and blue make a green, green is therefore the complementary colour of red, and vice vcrfu. The complementary colour of the orange formed by yellow , and red is the blue. The complementary colour of yellow is violet. The term does As the complementary colours meet together in a great Ne J?o^nTa« '^^ number of cafes, we have thought it neceOary in the outfct theory oi the to give them that denomination, which makes no change in folar light, ^^^Q rgfults, by which Newton proves that the folar ray is compofed of an infinity of homogeneous coloured rays. If the fpe6lrum is divided into two parts at the point where the green commences, all the homogeneous rays of the lower part, that is tq hy, from the beginning of the red to the be- ginning of the green, are complementary to thofe of the upper part, that is to fay, from the green to the violet ; and that in the natural order of their appearance. The denomination of complementary colours has no other object but to point out two colours which are found together very frequently ; and to avoid, by this fimple medium, the circumlocution which their diftinc^ion would lead to. Complementary Whenever two coloured fhadows are feen, they are nearly colours of tsvo ajy^^ays complementary to each other; that is to fay, if the * fliade of one is red, orange, or yellow, that of the other is green, blue, or violet, 5 When MEMOIR ON COI-OUREP SHADOWS. 25 When the number*of the (liadows is three, one of them is of three j alnfoft always complementary to the other two. When there are four (liadows, two of them are fometimes of four, complementary to the other two; at other times, one of the ih^dows is complementary to the remaining three. When there are only two coloured ihadows, one of them is One of the fha- always of the colour of one of the bodies which refle(6ls the fg^fJJ'e colour as light. If the apartment, in which the fhadows are feen, is the reflected commanded by a covering of flates which reflects a bluilh light "S^'» on the plane where the fliadows fall, the two colours are blue and orange ; if the covering is of tiles, the colours are nearly the fame. If a meadow or trees refled light into the apart- ment, .the ftiadovvs are green and red. If the apartment has which may be coloured hangings which refledl the atmofpheric light or ^^at^^^^^^ j. ^^^"" of the fun, the fliadows will participate of the colours of the lights, reflected externally and internally. When the light is refleded through glazed windows upon or by paffing the plane where the fliadow is feen, as the glafs is rarely co- ^'^^Q^S^ S^afs, lourlefs, and generally tinged with green or violet, according as iron or manganefe predominates in its compofition, the fhadow participates in the colour communicated to the light in its paflage through the glafs. If the furface on which the dlfl^erent lights are received be or by the colour ilfelf coloured, the colours of the ftiadovv will be aflfbaed by it, °^J^f fujfaceoa .1 , r .11 1 ,. I which the iha- and the problem will become more complicated. dow is received. From the obfervations we have collected, it follows na- Inferences. turaliy, that the coloured fliadows of the interior of an apart- ment are capable of yielding all the colours of the fpedrum ; that thefe colours arfe governed by thofe of the bodies which reflefl the light and illuminate the furface on which the co- loured fliadows are obferved. Thus far thefe obfervations Other comple- ofl^er nothing which could not have been forefeen by every ^^^^^^V "^^" " J J dows not pro- perlon who had refleded a littl^ on fliadows; but that which duced by dired is remarkable is, that thefe fhadows are almofl: always accom- ^^^^^*°^* panied by other fliadows whofe colours are complementary to the refledled colours, although no body is difcovered which is capable of refle6ting thefe forts of colours. Here then is a new fliadow which feems conftantly to ac- company the firf^, whofe colour has a peculiar affinity for that of the light which produces the primitive fhadow, and depends on caufes which we purpofe to examine in a fubfe- .quent memoir^ Part OQ MEMOIR ON COLOURED SHADOW*. Part the Third. Shadows from IF in a clear moon-light night, at a time when the lamps different colours. ^^^ alight in Paris, an opaque black body be brought near a white paper, enlightened both by the moon and a lamp, two diftind coloured lliadows will be perceived, one reddifli, the oiher bluifh. If a taper, a candle, a lamp, or any other light, be brought near a white pafteboard enlightened by the moon, an opaqup body placed at a fmall diftance from the pafteboard, forms two coloured ftiadows ; that occalioned by intercepting the light of the moon is reddifti, and that produced by the other light is blue. Thefe two ftiadows may be obtained by enlightening a fur- face with the atmofpheric light and that of a lamp ; but this requires that the light of the atmofphere muft enter the r,oom where the experiment is made, through a fmall opening, in order that the fliadow may be well defined when this light is fingle. Theeffeawas By admitting the light of the atmofphere into a darkened not varied by room through an Opening of a decimetre(four inches) in diameter, the nature of one , .„ .^ . ,. n i i i i • i- i , , combuftible and illummatmg a white palteboard by this light and that of a body made ufc lamp, we have found that when the pafteboard was one or two * metres (yards) from the opening, two coloured ftiadows were produced; that of the atmofphere is conftantly red, and that of the artificial light, blue. We have employed the lights from coals, wood, tapers, candles, alcohol, and even hidro- gen gas. The greateft part of the ftiadows obtained from two different lights are of two tints, the one reddifti, the other bluifti. The variations in (lie colour of ftiadows are independent of the intenfity of the lights which illuminate the ftirface. We were careful in all the experiments we are going to relate, to place the light at fuch diftances that they fliould enlighten equally that part of the white pafteboard on which the ftiadows were projeded ; and to this end we followed the method made ufe of by Bouguer, and which confifts in receiving through two holes, on a piece of oiled paper, the rays from two dif- ferent lights, and removing the ftrongeft, or bringing forward the weakeft, until the two lights were of equal intenfity ; .always being careful to place the eye at an equal diftance from the two enlightened points. The MEMOIR ON COLOURED SHAPOWS. 27 The experiments were made in a dark room, every part Precautions »n of which was painted black, for the purpofe of deftroying the ^^^^^JJJ.S^^^J'^ ex- cplour produced by refle6led light. We at firfl illuminated the pafteboard by the light obtained Shadows from from the corabuftion t)f fifli-oil in a common lamp, and by the ^jfj^^^en gas and light of hidrogen gas, produced by the diflblution of zinc in fulphuric acid weakened with water. The (badow produced J)y intercepting the light of the hidrogen gas, was reddifh ; that ariting from intercepting the light of the lamp, was bluiih. At the beginning we only ufed a feeble light from the hidro- gen gas. Being fearful that the colour of the fliadows might be occaiioned by the weak light, we filled a bladder with the gas, and by compreffing the bladder ftrongly, produced a powerful bright light : the plane illuminated by this light and that of the lamp, afforded a fimilar refult ; the fiiadow from the hidrogen gas was reddifli, that from the lamp bluifli. Qn enlightening the pafteboard by the light of a lamp and from a lamp and that of alcohol, the interception of the light of alcohol pro-^'^°^°^> duced a reddiih fliadow, and that of the lamp a bluifli fliadow. By illuminating it with the light of the lamp and that of a from a lamp and candle, the (hadow from the candle was black, with a light- ^ '^^'^^^i reddifli tinge ; that of the lamp was black, with a light-bluifli tinge^ The pafteboard being illuminated with the light of a lamp from a lamp and and that of a taper, the ftiadow from the taper was black flightly ^ ^T?^^* reddened, and that of the lamp, black a little bluifti. The pafteboard illuminated, at the fame time, by the light from a lamp and of a lamp and that from the combuftion of wood, the fhadow ^°° ' thrown by the light of the wood was a violaceous blue ; that of the lamp a reddifli yellow. The experiment was tried with wood burning with difficulty. In different and producing little flame; with very dry wood producing ^^^"* much flame; with chips of wood producing a white flame, which reddened that of the lamp. When the furface was enlightened with lights of equal intenfity, the coloured fliadows offered little variation ; that proceeding from the light of the wood was violaceous blue, that of the lamp reddifli yellow. The firft experiment was repeated in glafs-houfes where The experiment wood is burnt. However bright the flame might be which '^JP^^^^'* '" * was emitted through the working flues, the fliadow produced where wood is by it on a furface alfo illuminated by the light of a lamp, was a ^"'""fj violaceous blue, while that from the lamp was reddifli yellow. On 28 MEMOIR ON COLOURED SHADOWS. in an iron forge J On illaniinating the pafteboard by the h'ght of a lamp and that from the combuftion of culm in an iron forge, the (liadovV arifing from the light of-the culm was bluifh, and that from the lamp reddith. In a glafs-houfe On illuminating the pafteboard by the light of a lamp and burnt • '^^^ ^"^^"^ ^^® culm burnt in the furnaces of a glafs-houfe, where the brilliant flame of the working flues reddened that of a lamp, the refult was fimilar to the preceding: the light from the culnv produced a blue fliadow, and that of the lamp a reddifli fhadow. with a lamp and When the pafteboard is illuminated by the light of a lamp "^° * and that from the combuftion of charcoal, the fliadow of the charcoal is blue, and that of the lamp red. The pafteboard illuminated by the light of a lamp and that of charcoal urged by the large bellows in a chemical furnace, fo as to produce a whitifli light as well as that violaceous light fometime* obferved in the furnaces of a forge and in tall fur- naces, conftantly afforded the fame refult. In thefe two cafes the fliadow from the light of the charcoal was bluifli, and that Pmbabillty that from the lamp reddifli. The identity of the colours of the the colour of fliadows obtained in thefe three experiments with charcoal^^ the fliadows is • r, , r ,r^ - ^ produced by the "o^w'thftanding the colour of the flame was different m each nature of the experiment, leads to an opinion that the refult depends on the nature of the combuftible. Neverthelefs, to obtain more prO' bability, we made furtber obfervations. We filled a chemical furnace with charcoal, and having covered it with its dome for the purpofe of comparing the fliadow of the dire6l light of the violaceous flame arifing from the combuftion of the char- coal, with that of the light of a lamp, we took notice of the fhadows of thefe two lights at the moment when the flame Singular change appeared at the fummit of the furnace. F6r a confiderable of colour in the ^j^^^ ^^ obferved that the colours of the fliadows were very Ibadows* „ uncertain : fometimes the fliadow of the lamp was blue, and that of the flame red ; at other times the fliadow of the flame was blue, and that of the lamp red. This alternate change in the colours of the fhadows from blue to red, continued until the charcoal, which was in the upper part of the dome, was completely inflamed ; then the colours of the. two fliadows be- came fixed, that from the flame of the charcoal became bluifli, and that from the light of the lamp reddifli. Repetition of As, from the obfervations of feveral perfons to whom thefe the expenm^t Jgf^l^^s ^gjg commui\icated, we were induced to believe that y urnmg c ^^^ MEMOIR ON COLOURED SHADOWS. ^ the great I'ntenfity of the light of charcoal obtained by its com* charcoal in oxi- buftion in oxigen gas, might change or make fome variation ^^"8'^^» in the colour of the fliadows, we ignited the extremity of a piece of charcoal, and urged its combuftion by a jet of oxigen gas ; tlie gas was contained in a bladder, which was prefled ♦ by the arm; the light obtained was extremely brilliant. A with a fimllar white parchment, illuminated at the fame time by this light ^^ " ^' and that of a lamp, prefented two coloured fliadows; that from the light of the charcoal was blue, and that from the lamp red. From the experiments we have detailed it refults, that the Summary of the fliadow of thelight of hidrogen and of alcohol is reddifti, when ^^P"^"^^"'^ > that of the lamp is blue ; that the fliadow of the light of wood, of culm, of charcoal, is bluifli, and that from the light of the lamp is reddifli; and as hidrogen and alcohol contain lefs , carbon than oil— and dry wood, culm, and charcoal contain lefs hidrogen than oil ; it would feem that the blue and red whence It Is in- colours of the fliadows of the two artificial lights, bear a relation ^^\^^^ that the • I I r r colour of the to each other correfponding with the proportions of thefe two ihadows depends combuflibles ; that the light produced by a fubftance in which "" *^^ predomi- hidrogen predominates, gives a reddifli fliadow, and that pro- gen ©r carbon." duced by a fubftance in which carbon predominates, affords a bluifti fliadow. Although our experiments appear to lead to that conclufion, and we took great care to be certain that the red and blue fliadows produced by the two lights were independent of the rapidity of the combuftion and intenfity of the lights ; never- thelefs, we dare not hazard the prefenting this refult as forming a general law; we prefer waiting until time and new experi- ments ftiall confirm or deftroy them. Recapitulation. FROM the obfervations and experiments related in this memoir, it follows, l/.-That the fliadows formed by the dired light of the fun and that of the atmofphere, vary from meadow-green to a violet-black, in a gradation through the blue, indigo, and violet ; and that this variation depends on the intenfity of the light (of the fun) compared to that of the atmofphere. 2d. That the fliadows formed in apartments by the light of the atmofphere and reflected lights, may prefent all the prif- matic We refumed. 30 SUBSTITUTE FOR GUKt-AK^BlCT. matic colours, more or Icfs changed by black ; and that the tints of the fliadows obferved are always complementary to each other. 3rf, That the fliadows produced on a pafteboard illuminated by artificial lights, are reddifli and bluifti, more or lefs dee'p ; and that very probably the bluifti and reddifli tints of the fliadows depend on the proportions of hidnogen and carbon in the combuftible bodies. ii4 '■ ^ Thefubjeato We purpofe, if the Inftitute judges this Tubje6i worthy ot their attention, to make known, in other memoirs, the expe- riments we have made to determine the different caufes which contribute to form coloured fliadows in every particular cir- cumftance. V. Account of the Preparation of the Hyacinthus nan fcriptus, or coffunon Blue-Bell, as a Suhfiitute for Gum-Arabic. In m Letter from Mr. Thonas Willis of Lime-Street, London, com- municated to Charles Taylor Efq, Secretary to the Society of _ Arts *. SIR, b'^MT^Delux ^ HAVE obferved in the Appendix of the lafl Monthly refpeftinggum Review, in their Report of the Chemical Annals, No. 115, from the hya- ji^^^ mention is made of a letter froni Mr. Deyeux, to the fcriptua. authors of the Annales de Chimie ; in which an account is given that a gummy fubftance had been difcovered, by Mons. Deyeux, to be contained in the bulb of the plant called hya- cinthus non fcriptus ; and that the reviewers only fay, " This " article does not at prefent require any further notice than annunciation." As I know. Sir, your benevolent difpofition in promoting and encouraging the arts, the fciences, and manufaflures of this kingdom, I beg leave to offer the follow- ing obfervatlons on the above-mentioned article, which I think a fubjedl proper to lay before your mofl excellent Society, and which I have no doubt may become of national utility. ♦ Exlraflcd from the Society's Memoirs from page 202{ The filver raedal was adjudged to this Communication. 4 In SUBSTITUTE FOR GUM-ARABIC. . 31 In the year, 1794, whilft colleaing plants in a wood for DIfcoveryof this botanical fpecimens, I obferved that the root of the hyacinthus ^^^hor^^n 1794 non fcriptus, the plant commonly called blue-bells, or hare- bells, was extremely mucilaginous ; and on tafting it, I dif- covered only a very flight pungency. I colle6ted a pound of the bulbs, and, after flicing and drying them before a fire, they yielded about four ounces of powder. I thought that by keeping the powder fome lime, the little acridnefs might gb off, as it does in the arum-root powder. I tailed it about fix months after, and found it perfedly infipid. I concluded it might be rendered ufeful for food or nouriftiment, but at that time purfued the matter no further. In the fprin? of 1800, gum-arabic havincr been a long time PropofalmiSo© , fr, , . .• r T.u 1.4K- -1 • to ufe it inftead very dear, and likely to continue lo, I thought this mucilagi- q/- g^jj^^a^abic. nous root might anfwer fome of its purpofes, for external ufe. I therefore procured feven pounds and a half of the bulbs, which, when diced and dried, produced two pounds of pow- der. Being foon afterwards in company with Mr. Charles Taylor, Secretary to the Society of Arts, &:c. I mentioned to him that I had difcovered a root which grew in great plenty • - in this kingdom, yielded a very ftrong mucilage, and which I imagined would anfwer the purpofe of gum-arabic, in fome of the manufactories. He faid, if I pleafed, he would fend fome of it down to Manchefter, to be tried by the calico- printers. Three or four ounces of the powder were given him, and Trial at Man- fent down there : he was informed, upon trial, that it an- ^^^j^^ ^^ ""* ^'' fwered the purpofes of fixing the calico-printers colours, equally as well as gum-arabic ; and in the fame proportion, of an ounce and a half of the powder, to four ounces of the mordant. Mr. Taylor received the famples of the printed cottons on which it had been ufed. On the 15th of January, 1801, I furnilhed Mr. Taylor with eight ounces more of the powder ; but have not lince heard the refult. As this root can be eafily procured, and ufed at a lefs price The root la than gum-arabic has been ibid for feveral years paft, I think *^^^^P* it may be rendered of great utility ; and the Society of Arts, &c. by patronizing it, may be the means of making it a public benefit. Care 32 SUBSTIT'UTE FOR GUM-ARABIC. Inftruftjons Care (hoiild be taken, and advice given, tliat Ihe wood^ [he'i^'i'tfand ^^^uld not be left deftitute of the roots ; and it would be ad- fecuring their vifeable to offer premiums for the cultivating the roots and growth. offsets, as they are very increafing. By fuch means a con- ftant fupply may be had, if the roots anfwer the intended purpofes. I do not prefume to offer any thing refpe6ting the mode in which the Society may think proper to divulge the difcovery, and promote the ufe of thefe roots; but I imagine, that if the roots are bruifed and ufed freth, they would anfwer Ihe purpofe better than when dried ajid powdered ; and as it is now a proper time of the year for taking them up, and will continue to be fo for two months, I wifti that the difcovery may be made known as foon as poffible. I have fent you fpecimens both of the dried roots and pow- der, that they may be feen at the Society's rooms, by the calico-printers. What I have done have been fcorched a little in drying; but the colour would be much better, if proper care was taken in drying them. I am. Sir, Your mofl obedient Servant, Lime-Street, THOMAS WILLIS. March 17, 1802. To John Baker t Efq. one of the Mem- bers of the Society of Arts, S^c. From the trials made before the commrttee with this powder, with hot and cold water, from famples of the printed cotton produced which had been printed therewith inflead of gum fenegal, and from experiments made in Manchefler, it ap- pears that the hyacinthus non fcrlptus may, in fiiany cafes, be found a ufeful fubftitute for gum-arabic. A Memoir VINOUS FERMENTATION. 23 VI. A Memoir on Vinous Fermentation: by Cit. Thenard *. 1 HE vinous fermentation has hitherto received more atten- The vinous fet" tion than the acetous or putrid, not perhaps that it has any ^J^njed to°be. thing in it more remarkable, or more worthy of our confidera-caufemoft ufe- tion, but becaufe it is in the natural order of things, to take * more intereft and fet more value on what is of moft immediate Utility. The date of the difcovery of the vinous fermentation ap- Known tothe pears too welleftabliaied to be called in queftion. AUhiftorians "™°? ^""^°' *^ . . , , nations, agree in laying, that the molt ancient nations knew how to prepare fpirituous drinks. It afcends therefore to the remoteft times ; and, if we pay any credit to the poets, we muft carry it back to the fabulous ages. Indeed it would be furprifing, Its phenomena if it efcaped the notice of the earlieft of men. An ebullition ^ ^' ' * arifing fpontaneoufly in a liquid, a whole mafs riiing of itfelf, a fweet liquor becoming vinous, the change of a faccharine matter into an ardent fpirit, are all extraordinary things, cal- culated to ftrike the attention, and awaken the defire of tracing them to their firft caufes. Accordingly there is no phenomenon ^^^ have led t« more early obferved, and none that has been the fubje6t of ^^[5. more confideration, or has given birth to more experiments; yet, from one of thofe contrafts that rarely occur in the annals hitherto little of fcience, though it has been the mofl ftudied, there is not ^"^^"* perhaps one, with which we are lefs acquainted. It has been Alichemifts a rock, on which the endeavours of chemifts in all ages have explain it» fplit. Becher, fo celebrated for his fubterranean phyfics, Siahl, the Neftor of the ancient chemiftry, Boerhaave, whofe ideas were fo great, Rouelle, to whom fcience is indebted for part of the progrefs it has made during the laft half century, and Macquer, that mafter in the art of writing, all failed in their attempts to penetrate this myftery of nature. Lavoilier, who except Lavoifier was capable of furmounting the greateft obftacles, is the only tmt^rog^iX perfon, who, enlightening the whole fphere of chemiftry by it. his genius, travelled this obfcure path without wandering out of his road. His inquiries into fermentation will ever remain His inveftlgation a model of vegetable analyfis. In this, as in every thing elfe vege^blf ^alv- * Annals de Chimie, June 1803. p. 294. Vol. VII.— Janu.\iiy, 1804. D ke 34? VINOUS FERMENTATION. he did, he obferved that firidnefs of dedudion and accuracy of operation, which are liis charaderiftics, and which may be confidered as tlie fourcc of the fplendid difcoveries, that will But he left it for ever illufirate his name. Still, notwithflanding the ex- imper c . cellence of what he did, he was far from leaving nothing more to be done. Though he flied great light on this part of fcience,'* the obfcurity with which it was enveloped was fo great, that it is flill feen only through a raift. This is a truth that did not efcape liimfelf ; he was well aware that he had only laid open tile path to the goal, which no doubt he would ha;i'e reached, no doubt he would have completed the career he had begun with fuch fuccefs, had not death, jealous of his fortune and glory, robbed fcience of his labours. In fermentation All we know of fermentation in fa6l is confined to this, that fugar IS convert- ^^j^^ faccharinc matter is converted into alcohol and carbonic cd into alcohol r • ^• r i n andcaibonic acid by means of an nitermediate fubuance. But what is the acid, by means of j^j^^m-^ of this fubftance ? and how does it a6l on the fugar? fubftmce. But Thefe two grand queftions form the fubje(5l of the prefent what is this? memoir; queftions that have been often attempted, without a£l? °^ °^ ' ever having been folved. Some have thought, that the ferment- IraagineJ to be ing principle refided in the extradive matter. Others would have ^traftive mat- jj_ ^^ j^^ -^^ ^j^^ mucilage, becaufe this more frequently accom- mucilage, ' panics the extra<5live matter. Some, again deceived by the ^^'^.^'i' . „ . prefence of tartar in wine, have imagined they found in this which laft IS not ' ,. t -r • n i r <• ■ 1 ri i found in all fer- the true torment ; but if, mltead or confinmg themielves to the menting liquors, fermentation of the muft of grapes, they had turned their at- tention to that of other juices, in which analyfis cannot difcover the exiftence of this fait, they certainly would not have fallen into this error. Others, laftly, inconfiderately adopting all thefe or a mixture of opinions, have afierted, that a mixture of thefe different matters * ' ^^* prefide as it were over fermentation, effe6ling the decom- pofftion of the fugar, and its converfion into alcohol *. Of thefe hypothecs fome are evidently falfe; others are feducing, and acquire; from fpecious reafoning fome degree of probability. But before we admit them, we mufl confult ex- * Mr. Thenard here gives a long note, to prove he had not feen the prize elTays written in 1787 and 1788 by Fabroni, from whom fome pel fons at Paris accufed him of having borrowed, and to fhow, that Fabroni and he differ eflentialJy in this theory,* but it is here omitted as irrelevant.. T, perience ; I VINOUS FERMENTATION. 35 perlence ; we ought, leaving them all out of the queftion, to deduce from obfervation the theory, which we are too apt to form beforehand. If the genius of Stahl, inftead of giving Stahl mifled by birth to phlogifton, a being that never exifted but in the JjyP^^^^'J^' J^* briihant imagination of that extraordinary man, had inter- periment. rogated nature by means of experiment more than he did, perhaps it would not have gone aftray ; perhaps Stahl would have difcovered the truth, and deprived France of the glory of having produced the author of the modern theory of che- miftry. Such is the courfe I have purfued. Before I formed Faasobferved or adopted any fyftem, I obferved fads, and deduced from ^ them confequences, which, it appeared to me, muft guide us to the view of what paffes in hquors under fermentation. But in a fubje6l of fuch nicety nothing is more eafy than to deceive ourfeives ; and it is particularly for the purpofe of correding my notions, if they be not juft, that I fubrait to the clafs the refult of my inquiries *. My firft obfervations were made on the juice of goofeberries. He firft examla- vvhich I had^ ftrong reafons to prefer to any other ; its fermen- |y.J°°3^g J^JJJ tation proceeding with moft celerity, fo that it is confequently meriting moft beft calculated to throw light on the caufes that produce it. ^"'*^^ ^5 All my refearches were direded at firfl to difcover the matter, in order to dlf- that ferves as a ferment. It would be making a great ftep, asThe'fermtn/* and almoft refolving the problem, or at leall difcovering a number of truths not yet known, to determine the nature of this matter, and toafcertain whether it be always one and the and whether it fame, or whether there be feveral that poflTefs this property, fubftance*^ or*"^ This important queftion had ftruck me long ago : I had even feveral. meditated upon itoccalionally, and promifed myfelf to attempt its folution, when the Inftitute propofed it as a fubjed of a prize. This was an additional ftrong motive to my purfuing it. 1 was far from being difpofed to admit feveral fermenta- Hefuppofed it live principles ; «very thing led me to believe, that there was Jl ^'^^^^^ but one, and that it was none of thofe hitherto fufpeded, fince in fafl neither extraftive matter, nor mucilage, nor tartar, &c. ads upon fu^ar. But this required pofitive demonftration ;an'i this, though and though I have yet no abfolute proofs of it, as it is by no "d,' mS'prt."' means demonftrated, that there are feveral, and one is ob- bable. jerved on all occafions, this opinion feems to me at prefent to deferve the preference. . * This paper was read to the National Inftitute. D2 Though 36 Goofeberry juice contains a (light- ly glutinous matter, which, feparated by filtrationj occafioned a mixture of fugar and water to fer- mcnt. and become vi- nous* Butasitfcarcely effefts this on fix times its weight J it may be prefumed to contain but a fmall portion of the fermentative principle. This ceuld not be obtained apart j not apparently altered by hav- ing produced fermentation j but it ceafed to yield ammonia. The germ of fermentation is therefore of an animal nature. not feparable by reagents. The author therefore had re courfe to fer • menution. VINOUS FERMENTATION, Through a linen cloth of clofe texture I prefled out the juice of a killogramme of goofeberries. It was turbid, and held in fiifpenfion a flightly glutinous matter, which I feparated by the filter, and waflied in a large quantity of water. As nothing is to be negle6led in experimental fcience, and the moft trifling fa6l frequently leads to important confequences, I fubje6led this matter to a regtilar examination. I firft mixed it with fugar and water, to fee whether it would caufe them to ferment ; and I foon perceived many bubbles of an elaftic fluid to be extricated, which I found to be carbonic acid. The effervefcence continued a week, and at the end of this , period the liquor was a pleafant drink, but flightly faccharine; it contained a great deal of alcohol, and might ealily have been mifl:aken for a wine not yet completely made. It may be fuppofed I redoubled my zeal and attention in the exami- nation of a fubftance, that offered me what I fought. It was natural firft to inquire, whether the whole of it were adapted to decompofe fugar ; but a fixth part of its weight being fcarcely able to effect this decompofition, I concluded, that it con- tained the fermentative principle only in fmall quantity. This I attempted every method in vain to feparate, and obtain apart: nothing therefore remained for me, but to compare it before and after it had ferved to produce fermentation. It was not apparently altered by this procefs ; being ft ill infipid, infoluble both in water and in alcohol, and aflfefting neither infufion of litmus nor fyrup of violets : but on diftillation it no longer afforded any trace of volatile alkali. This refult, at which I was not furprifed, and which a fecond experiment confirmed, was neverthelefs a ray of light, that confirmed me in the courfe I ftiould purfue. It fliowed me, that the germ of fermenta* tion was of an animal nature, it agreed with the ideas I had before conceived, and gave to my fufpicions an appearance of reality. I now examined the juice of goofeberries with great care, to difcover this animal matter, which I confidered already as the true ferment. As it was infoluble by itfelf, it muft be combined with fome fubftance, that held it in folution. All the reagents I employed failing to anfwer the purpofe, I had ■ recourfe to fermentation itfelf, and obferved the phenomena produced by it under all circumftances. I made my experi- ments on nearly a litre of filtered and perfedly clear juice. 4. The VINOUS PERMENTAIION. 37 The apparatus was placed in a ftove, where the thermometer Filtered goofe- Hood at 20'=' : it was not long before a fermentation was evident ; a^hea/of^zoS a large quantity of carbonic acid was prefently evolved ; much foon fermentedj froth was formed; the liquor loft its tranfparency, and it even ^3°blntc"icuf became fo turbid, that a fediment was thrown down, which was covertd with was more evident as the fermentation approached its end. This ^J"^^^* . ., ^ became turbid, fediment was of a yellowifli white colour, glutinous, void of anddepofited a tafte, grew brown on drying in the open air, and became f«di"ientof a (lightly acid. Thrown on redhot coals it burnt in the fame gimi^ous, in- ' manner as animal fubftances : diftilled in a fmall retort it af- fipid, grew forded a confiderable quantity of carbonate of ammonia even ana^ightW acid! cryftallized. It made fugar ferment with extreme prompti- On redhot coals tude. In fliort it was a fubftance perfedly analogous to the ^^j'^^j'{5iV.'* yeaft of beer. ftance, and af- I was eager to try whether this phenomenon were general, ^°/^^^ carbonate , ^° , ,. , r r • 1 • of ammonia as It ought to be accordmg to my mode or reaionmg: and m when diftilled. faa experience foon taught me, that it was common to all ^^ caufed fugar juice in a ftate of fermentation. The muft of grapes, the is prrfeaiy ana- juice of cherries, pears, peaches, aud apples, and the decoc- logous toyeaft. tion of barley and of wheat, afford yeaft in their fermenta- ™' fubftance •' ^ ' ■> common to all tion. The grape juice yielded more than the others, though fermenting lefs than that of goofeberries : accordingly it did not ferment J"^*^^^' . . fo readily as the latter. The juices of cherries and peaches yields moft next depofited nearly the fame quantity ; thofe of pears and apples ^ ^^^^ of goofe- aflbrded very little, which is the reafon why their fermentation The juices of is fo flow. I could have wiflied to have had a greater number P^ars and apples of fruits at my difpofal, that I might have varied my experi- ^henlre'they ments more: they were fufficient, however, to prove, that, ferment flowly. where alcohol is formed, a fediment of yeafl is commonly ]^^^^'°T°"'^ p ' formed where lorraed hkewile. II they who have any doubt on the fubjedl alcohol is pro- remaining will maturely coniider the two following experi- - Reward of Twentj/ Founds for the Jrtificial Frodu^ion of Falludium, JL HE following is a copy of a paper received by me under , cover, by the two-penny poft. It is written in the lame hand as a note which covered a fmall piece of the palladium menr- tioned to have been received by me laft Midfummer. (See Philof. Journal, June, 1803, Vol. v. p. 136.) Upon inquiry, I find, that Mrs. Forfter has received the fum of 20c£'. with inftruflions conformable to this paper. This original is cut indent-wife on the margin, and has part of a manufcript flourifli or paraph on each border, but no fignature. (COPY.) December 16, 1803. SIR, AS I fee it faid in one of your Journals, that the new metal It Is infifted I have called palladium, is not anew noble metal, as I have faid ^'^*' P^^J^dium . . . cannot be it is, but an impofition and a compound of platina and quick- formed by art; iilver, I hope you will do me iuftice in your next, and tell ^!i-^ ^ reward i» T -r y c ^r. n ■ ^< T. ^ oflerfd for any your readers 1 promile a reward of 20^ . now m Mrs. Forlter s procefs t© that hands, to any one that will make only 20 grains of real palla- *^*^*^» dium, before any three gentlemen chymift's you pleafe to name, yourfelf one if you like. That he may have plenty of his ingredients, let him ufe 20 times as much quickfilver, 20 times as much platina, and \ in ftiort of any thing elfe he pleafes to ufe : neither he nor I can make a fingle grain. Pray be careful in trying what it is he makes, for themiftake inuft happen by not trying it rightly. My reafon for not faying where it was found, was, that I might make fome advantage of it^ as I have a right to do. If you think tit to publifti this, I beg you to give the names of the umpires, as I have dbfij;ed Mrs. Forfter to keep the ' money till next Midfummer, and to deliver it only in cafe they can aflure her that the real metal is made by a certificate figned by you, and by them, on this check. I hope a little bit of whatever is made may be left with Mrs. Forftcr. letter 76 SCIENTIFIC NEWS. Letter from Lalande on the Meafure of a Degree of the Earth in Lapland*. Themeafurcof ASTRONOMERS have long fufpeaed, that there was hnd^bjTMauper- ^'^"^^ ^^^^^ ^^ ^^^ meafure of a degree of the earth taken in tuis, &c. fufpcft 1736 in Lapland, by Maupertuis, Lemonnier, Outhier/and e of enor. Celfius, becaufe this meafure was greater than it ought to Re-mcafured have proved according to all others. Mr. Melanderhielm berg^ &c. who*' '^^^ '^^'^ ^^^ 8°°^ fortune to obtain a repetition of this niea- found it to be furement. He informs me, that Mr. Swanberg, and three ^^elV^'^^^' °'^^^^^'' ^w^^^^"* aftronomers, have found the degree to meafure 57209 toifes in the latitude of 66*^ 20', which are 196 toifes Tht flattening lefs than by the French meafurement, and gives for the flat- i^'inhT^ tening of the earth ^\^, This agrees better with the other comparifons, and teaches us, that the figure of the earth is not fo irregular as was fuppofed, from the degree meafured in the north. Mechaingone to Mr. Mechain fet off on the 26th of April for Spain> whi- meafure a til- ^.j^^j. ^^ -^ ^^^ ^^ meafure a triangle of 93000 toifes, terrai- angle terminat- _ * , ° , ing at the balea- nating at the Balearic iflands, which will complete the grand ricifles. ^^^ important meafurement of the meridian, executed a few years ago by MefTrs. Mechain and Delambre. He is ac- companied by Meflrs. Le Chevalier and Dezauche, and his youngeft fon. This meafurement is very difficult, but no per- fon is more capable of furmounting difficulties than Mr. Me- chain, and we (hall have the 34th degree in the middle of thq ■whole arc meafured by Frenchmen. New metal. DESCOTILS has difcovered a new metal in the ore of platina, it is prefumed that palladium may be an alloy of this new metal with mercury. Abluc equal to Tbenard has difcovered a blue equally beautiful, and as fine u tramannc. ^^ ^^^^ ^^ j^p.^ lazuli, or ultramarine. Prize of gal- The National Inftitute has declared, that the galvanic prize vanifm deferred. n ^ i • ,i • o » Will not be given this year, Thefe three articles are from the Journal of VaU'Mons, * Journal dePhyfique, May, 1803, p. 400- Letter •ICIEKTIFIC WfiWS. TT Utter from Profcjfor Vrovst io J. C Delamctherie on a dan- gerous fulminating Powder'^, IN one of my late leaures, I made an experiment thai Dangerous ex^ might have been attended with ferious confequences to fome P"'"^^*^'- of my auditors. It is, perhaps, no exaggeration to fay, that the mixture of ^ oxigenated muriate with arfenic, takes fire with the rapidity of lightning. I am accuftomed to compare the quicknefs with which Mode of com- difFerent kinds of powder burn, by fetting fire to them in wkh^thaf of ^"* cannons of equal diameter, paffing each through a piece of gun powder. cork placed in water, fo as to fink in it almoft their whole length. In this manner I was defirous of burning the arfenical mix- A mixture of ture, by the fide of an equal quantity of gun- powder, in ^j^^^ ^^^ arfenic order to compare their flame and continuance ; but I had burnt with the fcarcely time to draw back a little after fetting fire to the two '^f^g^'^bSrftlhe* cannons, when the firft exploded and burfi:, breaking the cannon that con- glafs velTel, and throwing about the water in all the radii of ^^j'^^^'^''^^"^"- *' '^ ed It quite flat, the furrounding fphere. Though the mouth of the tube and andthrewabout the efcape of the flame were perfe6lly free, the cannon was ^^e water in burft from top to bottom, and fpread out as flat as a card. ]„ alldireaions. This powder is fo violent in its eflfeds, that I conceive it Its effefts are toa would be very dangerous, to attempt to make any ufe of it. ^j"^^'°"^ ^^ If two long trains be made on a table, one of gun-powder A long train of the other of this mixture, and they be in contad with each 'F.^'^f.^^P^^''.^ liK.6 liftntnin*'. •ther at one end, fo as to be fired at the fame time, you will ^yfee with great furprize, that one difappears like a flafti of light- IfJiing, while the other feems to burn with extreme flownefs. tetter from a Correfpondent on the Expediency of converting I'oreii^n Weights and Meafures into Englijk. To Mr. NICHOLSON. SIR, THE pleafure which your readers receive from the perufal of your Journal is fo much abated by the obfcunty arifing from the names of the French weights and meafures, that I Journal de Phyfiqae, May, 1803- p. 394. with fc 78 tClZVTtTlC NEWS. wifh to fugged to your confideration, that a rcduaion of them to Englifh terms, would be to you comparatively a fmall la- bour, in proportion to what it would be to the generality of your readers individually. Your labours tend to the ufeful purpofe of communicating fcience and general knowledge to the public of this country. To facilitate the acquirement of fuch knowledge, it fhould be communicated in the terms moft eafily intelligible to the* people ; not in fuch terms as require algebra, or a procefs in the Rule of Three, to give a precife idea of every meafure- ment. As your Journal becomes more extenfively circulated, there arifes a ftronger claim upon you from the public, in favour of the many who are too indolent, too bufy, or too ignorant to expound for themfelves this fpecies of hierogly- phics. I am. Sir, Your conftant Reader. ANSWER. The rule propofed to be followed in all our tranflations, though perhaps not precifely, and on every occafion, adhered to, is, that wherever the foreign denominations of weight or meafure are mere indications of the proportional quantities, (and may be confidered as pounds, ounces, or grains, or as yards, i'eet, or inches all through,) the original names are ufed without embarraiing the fubjefl with any redudlion into fra6lional quantities : In every other cafe the reduction is, or ought to be made. While I exprefs my acknowledgments to this reader for his advice and remarks, I beg leave to fay, that I heartily fubfcribe to his opinions as to facilitating the communication of knowledge, by the iimpleft: methods. It is my vvilh in the fide notes, and by every o^her means, to (horten the time, and affift the inquiries, of thofe whofe other duties forbid the indulgence of deep or continued refearches. W.N. ACCOUNT SCIENTIFIC NEWS, 79 ACCOUNT OF NEW SOOKS. A Syjlem of Theoretical and Practical Chefiiifiiy, in Tiuo Volumes Accum's fyftem with Plates. By Frederick Accum, Teacher of Prac-^ ^ enuftry. tical Chemifiry, Pharmacy and Mineralogy, and Chemical 0 Operator to the Royal Inftitution of Great- Britain. Octavo, Two Volumes i 733. and full Index and Contents, with Five Copper Plates, A. HIS work which, is dedicated by permiffion to the mana« gers of the Royal Inftitution, and patronized by a very re- fpeftable lift of fubfcribers, is drawn up for the ufe of fuch as are unacquainted with chemical fcience. The author, therefore, begins by defcribing fuch experiments as are beft adapted to exhibit the general nature of chemical a6lion. The laws of affinity, and alfo thofe which govern the phenomena of heat and light, are ftated by the method of fynthelis, and illuftrated by experiment. And thefe are fucceeded by the claflification of bodies ; namely, firft the principles un- decompofed, then the charafteriftic properties of the gafes, and thefe are fucceeded by the metals, alcalis, earths, &c.. The difplay of thefe, as to their properties and habitudes, by an orderly combination of general narrative and reafoning, with particular fadts, experiments or, operative proceflTes, conftitute the bufinefs of the prefent work, which will doubt- Icfs prove acceptable to the numerous cultivators of the fcience of chemiftry. i A praBical Ejfay on the Analyfis of Minerals, exemplifying the Accum's analy- bejl Methods of analyfing Ores, Earths, Stones, Iriflammable ^is of mineral*. Fojfilsy and Mineral Suhjlances in general, % Frederick Ac CUM, Teacher of PraStical Chemifiry, Pharmacy, and Mineralogy. London, 12 wo. 183 pages. ISO*. THIS active and indefatigable ledurer, has been requefted by his pupils and auditors, to dra^v up a {qI of concife direc- tions, to enable any per(bn not intimately acquainted with analytical chemiftry, to examine fuch unknown minerals as I be may meet with, and readily afcertain their compofition. In 80 SfclENTlFIC NEWS. In the accompliflimeni of this obje6l he has exceeded his firfi intention, and has not only given clear, and rather com- prehenfive inftru6lions for analyfing all tlie different genera, and principal fpecies of the bodies mentioned in the title, and commonly met with, but has alfo given examples of analyfis of the rarer or lefs abundant mineral bodies. Bofluf 8 hlftory j General Hiftory of Mathematics, from the earlieft Times, to <»f mathematics, »^- i j, . , Vr.- , i ^ -r. j /• . the Ml dak oj the Eighteenth Century, Iranjlated from t/te French of John Bojfut, Member of the French National Injii' tuie of Arts and Sciences, and qf the Academies of Bolos,na, Peterfburg, Turin, SfC. To which is affixed, a Chronological Table of themoji eminent Mathematicians, S-co. 566. p. Lon^ don, I SOS, One Vol. Oaavo. THIS juftly efteemed work is well tranflated under the in- fpe61i()n of Mr. Konnycaftle, of the Royal Military Academy at Woolwich, who has added an inlrodudory Preface, and the Table mentioned in the Title Paoje. A JOURNAL OP NATURAL PHILOSOPHY, CHEMISTRY, AND I ^.t : THE ARTS. FEBRUARY, 1804. ARTICLE L Defcription of an Apparatus, hy which the EfeSi of Atmofpheric Prejjure infupplyivg Wortri'Tubs and other Vejfels zvith Water on ike Syphon Principle, may he fecured againji any Interrup- tion to be caiifcd by the extricated Air. In a Letter from Sir A. N. Edelcrantz, Counfellor of the Chancery, and Private Secretary to the King of Svoeden, Member 9f the Sivedijh Academy, Sfc. fyc. To Mr. NICHOLSON, MY DEAR. SIR, vJ'N my late relurn from an agricultural tour in Scotland, t Introduaion 5 find you have in your excellent Journal, honoured me with J^^P^^^'"g the mention of fome ideas of mine, refpeding the applica- vours to fupply tion of fyphons to raife water, with lefs expence than ufual, wprm.tubs, &c. for coolers in diftilleries, condenfers of fteam-engines, &c. the aaion of th« The ufe of fyphons is fo well and To generally underftood, fyphon. that though the mofl obvious things do not always prefent themfelves firfl to the mind, it would have been furprizing if the fame notion had not likewife occured to others. In fadl, I have lince learned, that a perfon in America, more than twenty years ago, obtained a patent for ufing the fyphon to cool the worm-pipes in diftilleries, and though I neither know his name, nor the fpecification of his invention, I prefume it to Vol. VIL— February, 1804. G be 82 AtPARAtUS FOR l?ERfECTlNG THE bcfimilar to v^hat 1 have propofed. In addition i6v^hich, the ingenious contrivance of Mr. Howard, publiflied in a later number of your Journal, is alfo founded upon the fame h)droftatical laws. But whatever may be the cafe in refpefi to theory, no practical ufe feems yet to have been made of it, owing moft probably to un fore feen difficulties in the execution. The chief im- The principal of thcfe, in my opinion, as was mentioned thf TxTricatTon" '" ^^^^ former memoir upoH this fubjea, is the extrication of •fair which air from the water contained in the cooling veflel ; which air ftopsthccurrenujjgjj-jggj^p^jjjgj^ partly by its own elafticity under a diminiflied preflure, and partly by the heat, is accumulated in the upper part of the cooler, and interrupts the two columns of tht fyphon, fo as at laft to flop the motion entirely. For though it may polfibly happen, by the negligence of workmen, that the worm itfelf may not be fufficiently found to excludfe the external air preffing into the cavity, and introducing itfelf that way into the cooler, as is dated in the experiment of I^Ir. Howard; yet I am perfuaded that in moft inftances, this caufe may be taken for t life real one, inftead of the former, which can never fail to aft in proportion to the perpendicular height of the cooler, and the heat communicated by the worm.. As it is impoffible to obferve by what aftual means the air is produced, unlefs the whole apparatus were of glafs, fuch a miftake may eafily be made. In fad, if metallic pipes could not be made air-tight, even in a bended form, the exhauftions in air-pumps and iiill more in great condenfations * would be attended with almoft infuperable difficulties. P^or extrafting the air difengaged from the water itfelf, during the adion of the fyphon, which in a few hours time would neceflarily interrupt its motion, I have employed a few hours of leifure confiruCiiHg the following means, which I beg leave. Sir, to communicate to you; without pretending to claim a greater portion of your attention thap th^ir remote utility may appear to deferve. * In the experiments I made fome years ago, with an apparatus conil:ru6ted/or conde/ifing different gafes and/or producing a Jlronger artificial coldy than by any means employed before, I comprefled air in brafs pipes more than to ^y of its original volume, which if we fuppofe the cooler to be 15 feet high, is more than 50 times the dif- ference between the external and internal preffiue of air in the cooling worm of the new apparatus. On Not probable that this air •omes from without. Plan for ex- traftjng it. SYPHOJf ON A LARGE SCALE. * J3 On the top of the cooling veflel A, Fig. 1 . Plate V. let a A veffel filled fmall veflel B, called the air-veffel, be placed, communicating ^j.'^^,nTtop'^^ with A by a cock. With the top of B let another veflel C, and another at called the zvater-vefd be conneaed, having a cock C. Thefe ^"^^"J withX cocks have two parallel openings each, one for letting out air, upper partof chc the other for letting in water at the fame time to take '^s ^J^^-^^^jj'jj^^ place. Suppofe thefe three veflels to be filled with water cock only is and the fyph4m in adtion, the cock B open and C fliut ; then opened the ex- all the air produced in the cooler will rife through B and fill afcends, and the air-veflel ; and in the mean time the water will defcend. water defcends. The air-veflel being filled with air, let the cock B be fhut, ^J'^"^^^^,^PP" and C opened ; then the water from C will defcend, and the opened, the air air will efcape into the atmofphere. By this alternate motion oj^gf ^aJej^^fjug of the cocks, the air difengaged within the worm-tubs will in fiomaboTc. be continually extracted, as long as any water remains in C, . The principal object then mufl: be firfl to fupply the water The upper water in C, either by manual labour, or by a part of the mechanical "^jftheSl"'^' force employed to fill the artificial refervolr for the lower muft work with- branch of the fyphon ; and fecondly, to dired the alternative «"' «"'=^^'^^"^«- opening of the cocks, by a felf- regulating mechanifm ; which may be effeded in the following manner. Fig. 2. Plate VI. reprefents a fe6lion of the air-vejfel B, The cocks are B is the air and water-cock, communicating with the worm- flgat:'^ which tub or cooler beloWi A is the other cock for the fame when at loweft purpofe, communicating with the water-veflel C. A and B 3^^^^ ^^^''5"^^'^'^ being connedted by a metallic rod K L, their motions are fimul- upper cock ; and taneous, and the perforations are fo placed^ that when the when at highcft . ^, , r r 1 1 1 ^0^5 the con* twQ holes of one cock are open, thole ot the other are always trary. The (hut. E is a ball of lead or other weight, fixed on the lever a£tion is made O U, conneded with the quadrant F G, and the lever G H, turabl?ngweight,' the whole turning through one quarter of a circle round the Centre U ; m « is a part of a cog-wheel fixed to and Aiding along the quadrant G F, a6ling upon the teeth of the cock A, and forcing it, together with the cock B, one way or the other, as itfelf is moved by the levers U F or U G, either in the dire^ion from F to G, or from G to F* This alternate motion is produced by the floater POQR, (of which apian on a diminiflied fcale> is reprefented in Fig. 3.) having in its middle and hollow part a kind of fork O, through whi^h pafles the metallic rod H I, conne6ted with the lever H F, at the end of the quadrant GF. This floater in its afcenfion G2 lifts {gj{, SYPHON APPARATUS. lifts the little ball H at the end of the lever, and confeqaently the weight E ; and in defcending it ads upon the bail I, and forces the weight E in the contrary diredion, A fide viewr of this apparatus is prefented in Fig, 4. where the double openings in the cocks A, B, and the manner of fixing the weight E with its levers, are more diftindlly feen. In Fig. 2. the air-veflel is fuppofed half filled with air tranlinitted from the cooler. The cock B is fhut, and the cock A open, admitting water in place of the air. The floater is afcending, and when the fork O touches the ball H^ the weight E is Hfted, the quadrant begins to move from E to G, but the Aiding part mn remains in its place till the weight E, having pafTed the perpendicular and falling over the other .. fide, brings the point F in contaft with n, and forces at once both cocks in the contrary direflion ; by which A being (hut and B open, the air from the cooler rifes, and the water defcends. The floater confequently finks till it prefies upon I, drawing the weight E in its firft fituation, and turning the cocks again. This procefs will evidently continue to al- ternate. Every mechanical reader will fee the neceflity of turning the cocks in this apparatus by a fudden ftrpke. For if the floater were to z6t diredly and conftantly upon them ; there would be a certain moment when both would be (hut, and confequently the motion would ceafe. Another method Inftead of the Aider m n, the fame effe6l may be produced by c ains. 1^^ ^^^ chains, {Fig. 5.) on the ends of the levers FG, con- nected with the cock A ; the other apparatus remaining as defcribed above. This method may even in fome refpeCts ap- pear more Ample; but I have defcribed the other partly be- caufe I apprehend the contrivance to be new, and partly be- caufe the ufe of chains may in fome cafes be liable to ob- jections. An air-pump But I cannot avoid remarking that the moft fimple means of would be the gii a„d perhaps the bcA, on a fmall fcale, would be an air- fimpleft organ. • pump fixed on the top of the cooler, and connected with the pump that fupplies the artificial refervoir. And though the force required for extracting the rarified air, muft be in pro- portion to the perpendicular height of the fyphon; yet it cannot be more than what is required to raife a quantity of water necetfary to fill the place of the air, as in the former 3 apparatus PRETENDED NEW METAI.; PALLADIUM. 8^ apparatus. When it has been found by experiments^ how much air is extricated from a given quantity of water, running with a known velocity, under a given diminution of prelfure and heat ; the fize and power of the air-pumps may be deter- mined fo as to adt with full advantage, as long as tbefe cir-^ cum(lanc«s remain unvaried. But if they happen to change, the air-pump will either work too much, and expend an un- necetfary force, by extradting water after the air is exhaufted ; or too little, by extracting the air more flowly than it is pro- duced. On the contrary, it feems that the floater, if the yelTels and cocks be of fufficient fize, can never deliver more or lefs than is exa6lly required. This confideration, as well as the poffibillty of a conftant but would fupply of water for fmall veflels, without any pumping at all, J^^yy^^^^'^^ ^^'^Jl may in many cafes allow the firft apparatus to be ufed with apparatus, advantage, and even render it preferable, efpecially in elevated jyphons and great rarefadions, as mod commonly occur in pra£lice, when it would not only be very difficulty to keep the air-pump tight without great fridlion, but a quantity of vapour from the heated fluid would be expanded. This in- creafes the difficulty of the air-pump, but in the other con* trivance it is partly condenfed by the cold water in the'ajr- \'eflel trough, which it is obliged to pafs. I am with great efteem, My dear Sir, Your obedient humble Servant, A. N. EDELCRANTZ. II. Enquiries concerning the Nature qf a Metallic Subftance lately fold in London as a new Metal, under the title of Palladimn, , % Richard Chenevjx, Esq. F. R. S. and M.R. I. A.* 'N the 29th of April I learned, by a printed notice f fent Announce of a to Mr. Knox, that a fubftance, which was announced as a new"^'^"*^'^ ^*' metal, * From the Phllof. Tranf. 1803. i" *' Palladium, or newfilver, has thefe properties among/1 others ** that fhew it to be a new noble metal. " l.lt diflblves in pure Ipirit of nitre, and makes a dark-red " folution. 2i Green vitriol throws it down in the ftate of a re- ** gulus from this fojution, as it always does gold frpm a^ua regia, ; ---- — t,, 0^ jf $(5 FRETENDED NEW METAL; PALLADIUNf. metal, was to be fold at Mr. Forfler's, in Gerrard-ftreet* The mode adopted to make known a difcovery of fo much importance, without the name of any creditable perfon except the vender, appeared to me unufual in fcience, and was not calculated to inlpire confidence. It was therefore with a view to deted vyhat I conceived to be an im^pofition, that I pro- cured a fpecimen, and undertook fome experiments to learn it properties and nature. Its general pro- I had not proceeded very far, when I perceived that the ^' "• effe61s produced by this fubfiance, upon the various tefls, were fuch as could not be referred, in toto, to any of the known metallic fubftances. limmediatelyreturnedtoMr.Forfter, ^nd became poflefTed of the whole quantity which had been Jeft in his hands for fale. I could not obtain any information as to its natural ftate, or any trace that might lead to a pro- bable conje6lure. I^ummated fmall The fubflance had been worked by art : it had been rolled pieces.^ p^j jj^ flatting-mills ; and was offered for fale in fpecimens ponfifting of thin laminae. The largeft of them were about three inches in length, and half an inch in breadth, weighing on the average 25 grs. and were fold for one guinea. The other laminae were fraaller, in proportion to the price, roliih", like Subjefled to the fame treatment as platina, to procure a p. tina: Elafti- poJifl^efj furfacCj, palladium aOumed an appearance fcarcely to Flexibility con^ be dlftinguiflied from that metal. The lamince were not very iiderabic. Spe- ^igf^i^^ but were very flexible, and could be bent feveral times differing in the "^ Qppofitc dirc^ions without breaking. The fpecific gravity, fpecimens. I found to differ not a little from that which is flated in the printed notice, and to vary confiderably in different fpecimens. Some pieces of this fubf^ance were as low as 10,972, whil^ others gave i 1,482. " 3. If you evaporate the folution, you get a red calx that difFolves *' in fplrit of fait or other acids. 4. It is thrown down by quick- ** filver, and hy all the metals but gold, platina, and filver. 5. Its ** fpecific gravity by hammering, was only 11.3; but by flatting, ^* as much as 11.8. 6. In a common fire the face of it tarnifhes *i a little, and turns blue, but comes bright again, like other noble •' metals, on being ftronger heated, 7. The greatefl: heat of j^ ** blackfmith's fire would hardly melt it; 8. But if you touch it, ** while hot, with a fmall bit of fulphur, it runs as eafily as zinc, ** It is fold only by Mr. Forfter, at No. 26, Gerrard-ftreet, " Soho, London; in famples of five (hillings, half a guinea, and *.* one guinea eacl^/* rilKTENDtD NEW METAL; PALLADIUM, g7 Theeffedsof galvanic eleflricity Upon palladium, were tlie Galvanic cfFefts, fame as upon gold and filver. No oxidizement of the fubftance ^s &'^^<^ «' filver. took place ; but oxigen gas was emitted ; during the whole Jtime it formed a part of the galvanic circle in action, A lamina of this fubftance being expofed to the blowpipe, Became blue the fide removed from the immediate aciion of the flame ba- '^"^ ^^^' came blue; but the temperature at which this colour was produced, exceeded that at which (leel begins to lofe the tinge it had received at a lower heat. I expofed palladium, in an open vefTel, to a greater degree No oxidizement of heat than that which can melt ffold. No oxidizement ^>' ?''^"S Heat. ° Fuhon more eniued ; and, although the metallic flip was extremely thin, difficult than no appearance of fufion took place, even at the edges or ^^at of gold, corners. Upon increaiing the fire confiderably, I obtained a melted button ; but I cannot ertiraate the degree at which the fufion was efTeded. The button, by this treatment, had lofl a h'ttleof its abfolute F«fed button iV^eight ; but its fpecific gravity had increafed from 10,972 to more^dcnfe^^'^* ; 1 1,^7 1. It was of a grayifti-white. Its hardnefs was rather harder than iron, fuperior to that of wrought iron. By the file, it acquired the ^,re'fibrouf ^'^" colour and brilliancy of platina. It was malleable to a great cryftallized. degree. Its fra^lure was fibrous, and in diverging ftriac, which feeraed to be compofed of cryflals; the furface of the button alfo, when feen through a lens, appeared to be cryflallized. Palladium very readily combines with fulphur. I expofed Combines and .a certain quantity of it to a violent heat, without being able fu*i^^u7bv i°nl- •to melt it ; and^ at that elevated temperature, threw fome tion. Suiphuret Xulphur upon it. It immediately entered into fufion, and ^^^^''j" ^"'^ ^'"^ lemained in that fiate until the rednefs of the crucible was hardly vilible in the daylight. The increafe of weight in the button of the fulphuret, was fuch as could not indicate with exadlnefs the proportion of fulphur combined with it ; and I was fo limited in the quantity of palladium I could obtain on uny terms, that I thought it prudent to referve as much as po0ible for the inveftigation of more important properties. Suiphuret of palladium is rather whiter than the fubfiance itfelf, and is extremely brittle. Palladium, melted in a charcoal crucible, and kept in fufion Continued /or fifteen minutes, did not acquire any properties different ^?^°".^^P^'*" fxQOi thofe which I have already mentioned, infpeaking of the coal j no change. effea 33 PRETENDED NEW METAt J PALLADIUM. effefl of heat upon that fubftanoe. Hence we may conclude, that there is not any a6tion between charcoal and palladium. Allay. Palla- I put equal parts of palladium and gold into a crucible, for gray and fcfs * ^^^ purpofc of forming an alloy. The refult, owing to an accU duaiie, dent, did not weigh fo much as the fum of the quantities em- ployed; therefore, the proportions in this alloy were uncertain. Its colour was gray ; its hardnefs about equal to that of wrought iron. It yielded to the hammer; but was lefs du6lile than each metal feparate, and broke by repeated percuffions. Its fra6lure was coarfe-grained, and bore marks of cryftallization. Its fpecific gravity was 1 1,079. PaUadlum and Equal parts of platina and palladium, entered into a fuiion at platinaj denfer, ^ ^^^^ ^^^ much fuperior to that which was capable of fufmr Ids malleable. ,, ,. , / , ,t , r ,• „ r ,, . palladium alone. In colour and hardnels, this alloy relembied the former; but it was rather lefs malleable. Its fpecific gravity, I found to be 15, Ul. Palladium and Palladium, alloyed with an equal weigKt of filver, gave a divert whiter, button of the fame colour as the preceding alloys. This was harder than filver, but not fo hard as wrought iron ; and its polilhed iurface was fomewhat like plafina, but whiter. Its fpecific gravity was 11, 290, ITalladlum and The alloy of equal parts of palladium and copper was a copper: harder jjj^^jg more yellow than any of the preceeding alloys, and broke more eafily. It was liarder than wrought iron ; and, by the file, aflumed rather a leaden colour. Specific gravity 10,392, Palladium and Lead increafes the fufibility of palladium. An alloy of kadt more fufi-^l^gjpg metals, but* in unknown proportions, was of a gray grained, and colour, and its fra6lure was finegrained. It was fuperior to hard and brittle, qW the former in hardnef>>, but was extremely brittle. I foun(i its fpecific gravity to be 1 2,000. Palladium and Equal parts of palladium and tin gave a grayifh button, in- tm : grayiih, fgrior in hardnefs to wrought iron, and extremely brittle. Its brittle, compaa, ^ ^ fra6ture was comparand fine-grained. Specific gravity 8,175, Palladium and With an equal weight of bifmuth, palladium gave. a button bifmuth ; gray, ^jjj brittle, and nearly as hard as fteel. Its colour was very hard and ^ brittle. gray; but^when reduced to powder, it was much darker. Its fpecific gravity, I found to be 1 2,587. Palladium and Iron, when alloyed with palladium, tends much to dim inilhi iron. Palladium its fpecific gravity, and renders it brittle. Arfenic increafes the fufibility of palladium, and renders it extremely brittle, JFron^ PRETENDED NEW METAL; 1PA|,LADIUM. From thefe experiments, we may form the following tatle, ihewing the difference between the true and the calculated mean of fpecific gravity in the alloys of palladium. 89 Metals, Proportion, Specific gra- vity by cal- culation *. Specific gra- vity by ex- perinsent. DifFercnce. "Gold - uncertain. uncertain. 11,079 uncertain. J2 Platina - equal parts. 17,241 15,141 —2,100 Silver - equal parts. 10,996 11,290 + ,294 o B .2 Copper equal parts. 10,176 10,392 4- ,216 Lead - equal parts. uncertain. 12,000 uncertain. 1 Tin - equal parts. 9,34.0 ' 8,175 -1,165 Bifmuth equal parts. r*^ 10,652 12,587 + 1,935 '' ' Comparifon of the fpecific gravities of thefd alloys with the computed denfi* ties. I expofed ten grains of palladium to the adion of potafli, in Palladium fufed fufion during half an hour. The fubftance loft its brilHancy, ^iigh^°^'JJ ^j*. and diminilhed two grains and a half in weight; thefe were liancy. found in the potafh. The adlion of ibda upon palladium, does not appear to be With foda. quite fo violent. Ammonia, allowed to remain for fome days upon palladium. Ammonia in the acquires a flight bluifn tinge, and holds a fmall portion of ^e"minerox?da" oxide of palladium in folution. In all thefe cafes, the adiontion, and takes of the alkali is promoted by the contadl of the atmofpheric air, "P <'^' ^^^ ^^® "^^^ P^"*** ^^ ^ beautiful oraftge ; are partly re- diflblTcd. diffolved by fome of the alcalis ; and the fupernatant liquor of the precipitate formed by ammonia is fometimes of a fine greenilh blue. Sulphate, nitrate, and muriate, of potafli, or of ammonia, produce an orange precipitate in the falts of palladium, as in thofe of platina, when not in too dilute folution; and the precipitates from the nitrate of palladium are in general of a deeper orange. All the metals, except gold, platina, and filver, caufe very copious precipitates in folutions of palladium. Recent muriate of tin produces a dark orange or brown precipitate in neutralized falts of palladium, and is an extremely delicate tefl. Green fulphate of iron precipitates palladium in the metallic Hate ; and, if the ex- periment fucceed, the precipitate is about equal in weight to the palladium employed. Prufliate of potafli caufes an olive- coloured precipitate ; and water impregnated with fulphurette^l hidrogen gas, a dark brown one. Fluoric, arfenic, phof- phoric, oxalic, tartaric^ citric, and fome other acjds, together with tiieir (alts, precipitate fome of the folutions of palladium, and form various combinations with this fubftance. Such are the principal characters I have found in palladium, examined as a fimple metallic body. It does not appear that, in dating any of its properties, except its fpecific gravity, the printed notice has been guilty of mifreprefenlation. From PRETENDED NEW METAL; PALLADIUM- SI From thefe experiments, it would be difficult to fay of what Comparlfon of metal, or of what combination of metals, palladium confifts. ^J'" ^^"^y ^^^^ * . . ,. , . the other kwo\vn We could not fuppofegold or platinato bean ingredient m it, metals, as it is in fome meafure a6led upon by fulphuric and muriatic acids, and is wholly foluble in nitric acid. Silver is excluded, by theeffe6l of muriatic acid upon its folutions ; as is lead, by , that of the fulplmric. Tin, antimony, bifmuth, or tellurium, would have left an infoluble refiduum with nitric acid. No traces could be foundof any of the acidifiable metals ; and iron was looked for with particular care, but in vain. In a word, the precipitation by the metals, feems to exclude all thofe of cafier oxidability than mercury ; and this we fliould not fuppofe to be prefent, as copper is not in the leafl whitened^ when ufed to precipitate palladium. The ftriking fimilarity of many of the precipitates of palla- Itrefcmb'es dium with thofe of plalina, induced me to multiply the com- P'j^V"^ '" ^^"^ IT n , ir 1 t-rs of Its prCCipi- parative experiments ; and I conltantiy oblcrved contradictory tates, &^, fads. The fpecific gravity, eafy fufibihty, combination with , fulphur, precipitation by green fulphate of iron and by pruffiate of pota(h, together with other effeds, were fuch as I could not reconcile to the known chara6ters of platina ; unlefs I could fuppofe that a fubftance did exift, which could totally change its phyfical and chemical properties, or fo difguife them as to render them proof againft the evidence of chemical re-agents. The lighteft of the metals is tellurium ; yet, in order to pro^ duce an alloy of the fpecific gravity oF palladium, (fuppofing for a moment the real denfity of the alloy equal to the calcu- lated mean), it would require two parts of tellurium and one of platina ; and it is highly improbable, that fo large a pro* portion of tellurium could exift in any mafs, without being deteded. We have been told of very extraordinary anomalies in chemical affinities, by Mr. Berthollet ; and Mr. Hatchett has made us acquainted with fome, not lefs extraordinary, in the properti«s of alloys. Yet I think w^ ffiall ceafe to wonder// Uan alloy of at what has been related by thefe chemifts, when we leasn that/'^'*""'' andmer* palladium is not, as was fliamefully announced, a new firaple"^"''* metal, but an alloy of platina ; and that the fubftance which can thus matk the n>oft charafleriftic properties of that metal, while it lofes the greater nunmber of its own, is mercury. I confefs it was not from an analyiis of palladium that I was This was fyn- £r4 le^ to this rpfult j for I had convinced myfelf, by fynthefis, theticaiiy dif- ' ..„..-. y ^ J covered. ^2 PRETENDED NEW METAL J PALLADIUM, of its nature, and had formed the fubftance, before I could devifeany probable method of afcertaining its component parts. Admirable d'lf- In rcflecling upon the various modifications which fubftances pofal of pU- undergo when in union with each other, and on the variations tina and mercury i j • Vy which they produced in the laws of affinity by the intervention of new were prefented to bodies, I was induced to try whether by the affinity of platina each other and • i r i ^i i i . united.— Green W"" ^^^^ metal eafily reduced, it might not happen that a fulphatc of iron redudion of both would take place by green fulphate of iron, folution of pla- although no fuch effeft were produced upon each metal when tina} and alfo feparate. The raoft likely to fucceed, as being raoft eafily re- mercury. No ^"^ed, after gold, platina, and filver, was mercury. I poured precipitate took fome folution of green fulphate of iron into a fait of platin»a. The compounds ^"^ ^^^^ '"^"^ ^ ^^-^ ^^ mercury ; no precipitation took place were then n ix- I united the two liquors j and a precipitate exa611y referabling ed. Platina an(| ^{,^1 which is formed by green fulphate of iron in palladium, down together, was inftantly formed. I colle6ted the precipitate, and expofed The compound jj to a fifong heat; and, after repeated trials, obtained a me- was palladium, talh'c button, not to be diftinguiflied from palladium. It certainly is one of the moli extraordinary fads refpeding alloys, that two metals, by their union with each other, thould fo lofe the character i ft ic properties of each individually, that neither of them can be immediately detefted by the ufual Ijiethods. Nothing but an affinity of the moft powerful order I could produce fuch effects. But, to place the metals under the moil favourable circumftances for that affinity to exert its influence, and to promote their union, is not the refult of com-* mon methods. Among a great number which I have tried, many have failed, and none have been attended with uniform Palladium by the fuccefs. I have, however, formed palladium by the immediate immediate union m^JQ^j of platina and mercury ; and, as whatever may place the ot platina and '^ .. _ ^ ,,•',. ,. . . "^^ ' . mercury, apparent capricioulnels ot this combmation in a confpicuous point of view is not devoid of intereft, I (hall defcribe the means by which I have attempted to produce it, whether they •i failed, or were attended with fuccefs. SYNTHETICAL EXPERIMENTS. £jp. 1. It was not till after repeated trials of the mode juft mentioned, that I fucceeded in forming palladium. In many inftances, I obtained a button completely melted, of the . Specific gravity of 13, and fometimes more; not fo eafily fufed by ful|}hur as palladium; not foluble in nitric acid; and the abfolute F1.KTENDED NEW METAL; PALLADIUM. ^3 abfolate weight of which exceeded that of the platina originally employed. But, although this fubftance was not platina, I could not fay it was palladium. The moil fuccefsfal experi- Experiment i. ment by this method, was attended with the following cir. '^fj^fjj'g^ g"Jj cumftances. I difTolved one hundred grains of platina in nitro- ment of forming muriatic acid, and then put in two hundred grains of red oxide palladium by the of mercury, made by nitric acid ; but this not being lumcient tioned. to faturate the excefs of acid, I continued to add more, antil it ceafed to be difTolved. On the other hand, I prepared fome green fulphate of iron, and poured it into a long-necked raattrafs. I then poured the mixed folution of platina and mercury into the folution of green fulphate of iron, and heated the whole upon a fand bath. In lefs than half an hour, a copious precipitate was formed; and the infide of the mattrafs was lined with a thin metallic coat. The liquor was pafTed through a filtre, which I had weighed ; and the precipitate, after digeftion with muriatic acid, was well wafhed and dried. When I had colleded as much of this as I could, there re- mained upon the filtre 12 grains ; betides which, I had colled- ed264, in all 276. The fupernatant liquor flill contained a portion of mercury, and about eight grains of platina. There- fore, the 276 were compofed of 92 of platina, and 184 of mercury. From this it appears, that one hundred grains of platina, can determine the precipitation of near two hundred grains of mercury, by green fulphate of iron; and that, in this proportion, there is a reciprocity of faturation. The 264, collecled from the filtre, were expofed to a low red heat, and were reduced to 144. The twelve of the filtre would have given about feven ; therefore, the whole would have been 1 5 J . The fubflance was in the form of a fine powder, and had a metallic luftre. It was then put into a charcoal crucible, and fufed info a button. This button weighed 128 grains, and with the quantity left on the fibre, would have weighed 135. In this 135, there were 92 of platina; therefore it was com- It contamca ' pofed of about two parts of that metal and one of mercury. ^^'^^^ ^^° P*^* It was of the fpecific gravity of 1 1 ,2 ; was wholly foluble in mercury. - nitric acid; was eafily fufed by fulphur; was precipitated by green fulphate of iron : in a word, it was not to be diflinguifh- ed from palladium. Exper, 2. As another mode of forming palladium in the Experiment a., humid way, I put metallic iron into a mixed It^Iulicn of platina of'piatinaand* aDd ' ^4 PRETENDED NEW METAL; PALlADIUM.' mercury wis and mercury. Both m«tals were precipitated; and the ptefJ |,recipitatcd by cipitate was fubraitted to the fame treatment as in the formeil iron. The ^ fucccfs was lefs cafe; but the Tuccefs was not fo complete. Iron can pre- complctc* cipitate either platina or mercury feparately ; but green ful- phate of iron can perform its fundion only in favour of the affinity of platina and mercury. Their union is promoted by itsa6tion; and the effeds are, in all probability, fimultane^ ous. The combination of the metals takes place> if I may be allowed the expreflion, in their nafcent metallic ftate, and in a fixed proportion of mutual faturation* The union of the two metals, therefore, is in the prefent experiment lefs intimate, and the button which refalts from fufing the precipitate, is of much greater denfity. ^xp. 3. Zinc Exper. 3. The fame procefs was repeated, only ufing zinc IncompktL * inftead of iron, but the refultwas not more fatisfactory, Exp. 4. Mer- Exper. 4. Ipoured fome mercury into a folution of platina, rolution of pU- ^"^ heated them together for fome time. A precipitate took tina. place; but, upon fufing it into a button, I did not find it to be Incomplete. palladium. Bxp. 5. Mixed Expcr. 5. I diflblved the fame quantities of platina and mer* folutions of pla- (,jjj.y g^j. \i^ Exper. 1, in nitro-muriatic acid, and evaporated tma and mercury , i r ^ - 1 t » i -i- i 1 r f 1 evaporated and thotc loiutions together* 1 then volatilized as much as 1 could ignited. The of the mercury, at a red heat. At the end of the operation, ^^ ^^ I obtained precifely my original quantity of platina^ reduced to the metallic ftate; but not one particle of the mercury re- mained along with it. £xp. 6, 7. Exper. 6 and 7. The fame quantities of platina and mer- Piatinaandmer-^, diflblved In nItro-muriatic acid> were precipitated by cury precipitated •' . ^ r r j by phofphate of phofphate of ammonia; and the liquor was evaporated. The ammonia. No refiduum, in a glafly ftate, was expofed to a violent heat in a charcoal crucible; and I obtained a melted button, which weighed more than the original quantity of platina, and was of thefpecific gravity of 14,5. On account of the eafy fufi- Phofphuretof bility of phofphuret of platina, I likewife tried (o combine it platina. dlredlly with mercury, but could not fucceed. Ixp. S. Platina Exptr,8. I precipitated a mixed folution of platina and treci'pUa^ted^v ^^^^^^y» ^^y ^ current of fulphuretted hydrogen gas; and re* fulphuretted hi- duced (he infoluble powder. After many attempts, in which drogen. In one j obtained buttons of the fpecific gravity of 14,3 and 14,5, t inftance palia- ^ , . ... ^ . ° ,, % ,, .^ . ♦ dium. formed a piece weighing 1 1 grams, or the fpecinc gravity ot 11,5. This IfRElENUED NEW metal; ^Al.tAfiiUM. Q^ lli5. This laft was palladium; but I could not afcertaln the excefs of weight, as a part of the original precipitate had been loll. £xp. 9. I mixed a folution of muriate of platina with Ejcp. 9. Muriate rr , r i . • i /, • i • • T'l o* platina and prulliate or mercury, and obtained a (light precipitate. ■« "^ p^ufljjjg ^^ ^^^^ liquor was evaporated, and the whole refiduum expofed to a cuiy. Evapora* violent heat. This experiment did not fucceed. It was not jJe"t.^° ParSaf repeated fo often as the others ; but I have fome reafon to think fuccefs. it might be attended with fuccefs ; for I obtained, in one in- (lance, a (ew very minute grains, that were foluble in nitric acid. Exp. 10. I heated fome purified platina, in the form of a Exp. 10. AmaT* very fine powder, with ten times its weight of mercury, and mercuryl'"*Heat rubbed them together for a long time. The refult was, an drove oft' the amalgam of platina. This amalgam, expofed to a violent "^^^^'^y* heat, loft all the mercury it had contained ; and the original weight of the platina remained without incrcafe. Exp, 11, The belt method of forming an amalgam of Exp 11. Count platina, is that prefcribed by Count Muffin PuDikin. I dif- J^^'f amalgam folved a known quantity of plafeina in nitro-muriatic acid, of platina heated precipitated by ammonia, and evaporated the liquor. The fjJ^J^P^jjJ^*"^ refiduum was rubbed for a long time with a great quantity of mercury, and then expofed to a violent heat. Many operations failed ; in fome, I had a button of the fpecific gravity of 13,2. In one attempt, I fucceeded completely: from 30 grs. of platina, treated as above, I obtained a button weighing 43,5, of the fpecific gravity of 11,736, which had all the properties of palladium. Exp, 12. I fufed together, in a charcoal crucible, 100 grs. Exp. 12. Pla- of platina, 200 of cinnabar, 100 of lime, and 400 of calcined f.'"''* cinnabar, r 11-1 1 ,-i-ii , ""^^ ^^ hoxix. borax; and obtamed a button, which weighed more than fufed. the platina, and was of the fpecific gravity of li,7. It was not foluble in nitric acid; but combined with fulphur, at a fed heat. Exp. 13. In fome experiments I^hadmade, I found that jxp. 13. Pla- '• the furnace in which I formed thefe alloys, was capable of '^'"^ ^<^^<^<^ «"<* "^, melting platina, without the affifiance of any flux except -^"^^jj^ ^^g^^ *■ calcined borax. I therefore urged 100 grs. of platina, at a very ftrongheat ; and, when I judged the fire to have attain- ed its greatefl: intenfity, I poured mercury upon the platina, through a long earthen tube that terminated in the crucible, 2 and QQ PRETENDED NEW METAI, J PALLADIUM. and immediately withdrew the apparatus from the fire. No fenfible union of the metals had taken place ; nor had the platina increafed in weight. Exp. 14. Mer- Exp, 14. I put 100 grains of platina into an earthen tube* pSd"over°igl *"^ placed the tube horizontally in the above furnace. At nited platina. one end of it was a retort, containing 2lbs. of mercury. No effea. When the tube was at its greateil heat, the mercury was made to boil ; and the entire quantity parted over the furface of the platina, at that temperature. The experiment lafted one hour and a half; but the metals did not feem to have combined. Exp. 15. Pla- Exp. J 5. Mr. Pepys was fo obliging as to try the effeB, of ed"?nmercu'r"^" ^^^ ^^^^ powerful galvanic battery, in forming palladium. A and heated by piece of platina- wire was plunged into a bafon of mercury, galvani^. 3,^^ formed part of a galvanic circle. The wire was nearly in Little efiedt. „_ ,^ ,..- , ,, ^, tufion; but no combmation feemed to take place. The nature of this experiment did not allow of very accurate weighing; but the fufed globules of platina did not appear to have ac- quired the properties that conftitute palladium. Remarks. Dlf- Such are the experiments by which I attempted to form pofing affinities palladium. They were chiefly founded upon two principles; an imi a ion. ^jfp^^fjpg affinity, and aflimilation. In the one cafe, I endea- voured to prefent to the metals that compofe it, a fubftance which, on account of its affinity for fome menftruum necetTary for their fohition, and of their own tendency to combine in the proportions flated in E.rp. I, might caufe them to unite in the form of an infoluble compound. In the other cafe, I hoped to affimilate the properties of each, and, by making them fome- thingmore alike, to place them in the moft favourable circum- fiances for uniting. Exp. 1. was founded on the former, and Ejip. 8 on the latter of thefe principles. The platina al- In many inftances, when I did not form palladium, I obtained ways acquired ^ metallic button which was not platina ; and, when I did fo, it weight when its .11 1 1 • • 1 • «• 1 • properties were always weighed more than the origmal quantity of plalma thus changed, employed. In repeatirtg Experimenls 1,2, 4, 6, 8, 1 1, and 12, Mercury was I feldom failed ot having fuch a fubllai-vce. No effe6l.of this iftdirpenfable. j^jj^j j^q]^ place in any experiment, when mercury was not ufed along with platina; and the other metals were merely accelTaries, in promoting their union and precipitation. This i% fufficiently proved, by the uniformity of the refults in different proceHes, whether it was palladium or the fubftanco I now mention which was formed. The chief property vvhtch diftinguilhes PK.ETENDED NEW METAL; PALLADIUM. 5*7 dlftlngullhes the latter fabftance from platina, is its denfity. It is not iinufual to obtain it of a fpecific gravity folow as 13 ; very frequently 15 or 17. In the firft experiments, I fufpe6l- ed this h'ghtnefs to be owing to fome air-bubbles ; but repeated fufion, and comparative experiments upon platina, foon con- vinced me of the contrary. The augmentation of weight alfo, which the platina never fails of acquiring, proves that this metal has combined with fome ponderable fubftance ; and, in fad, the refult of thefe operations is, an alloy which is a mean betwixt platina in its pure ftate and what ha§ been called pal- ladium. It is, confequently, fubjefl to infinite variation. The firft efFefts which mercury produces upon platina are, to Mercury firft render it more fufible, and to diminifti its fpecific gravity. J^ort fuf»ble"a^ii(l The next new property conferred upon it is, the power of lighter j then uniting with fulphur ; and, laftly, it becomes foluble in nitric ^^JJ^^^ngJJjg a:cid. It is not however till the fpecific gravity is below 12, with fulphur; or 1 2,5 at raoft, that it has acquired this property ; and afl thefe and ihll more rr rs r „ . ,- ^ i r ^ ' r C ■ , ^cndcrS it foluble etiects follow the diredl order ot the increale ot weight i^ nitric acid, obfervable in the platina. vi<. under the It is not very difficult to combine a fraall quantity of mercury ,^"' ^ ^"^* ^ with platina ; but, to refolve the problem completely, and to The author of produce an alloy of thefe metals which fhall be of fo low a babw '^a? fo^'g fpecific gravity as 11,3, and fball be foluble in nitric acid, is fteady method of hot fo eafily accompli thed. From the repeated failures which ^o^^pofing it. I have experienced in thefe operations, I am much inclined to think that the author of palladium has fome method of forming it, lefs fubjedt to error than any I have mentioned. No doubt that perfeverance would put us in pofleffion of his fecret ; but, being prevented by want of leifure from purfuing thefe refearches at prefent, I have confined myfelf to eftablifhing the fa6t, and defcribing the proceffes which I have employed. Having thus acquired a certainty that mercury is a con- its decompofi- ftituent part of palladium, I made fome further experiments ^'P" ^^'"^^^^^'y upon it, with a view to its analyfis; but they have not been attended with fo much fuccefs. It might be expecled, from tlie great number of methods which have failed to form pal- ladium, that many might be found to decompofe it when formed. But I have found the converfe of fuch proceffes as did not fucceed in producing palladium, to be ineffedual in 'deftroying the combination. • • . ' Vol, VIT.—February, 1804. H analytical 98 PRETENDED NEW METAL; PALLADIUM. Anafytical ex- periments not luccefjful. Exce fs of mer- cury added to folution of pal- ladium. Palladium ftrongiy and durably heated. Cupellatlon. . Combuftion In oxigen. by gdvairifm. Wonderful dif- ferences between mixture and combination. Affinity not pro- portioned to the facility of union. ANALYTICAL EXPERIMENTS. Exp. 1, 2, and 3, The converfe of the fynthetlcal experi" ments 1, 2, 3, was made, but without any fatlsfadtory refult. Exp. 4. The converfe of Eip. 4 was made without fuc- cefs. I put fome mercury into a folution of palladium, and left them to^^ether for fome time. The precipitate which was formed was palladium, juft as it had been uled for the opera- tion. Exp, 5. I expofed different pieces of palladium to a very violent heat for two hours. In fome, a diminution of abfolute weight, with an increafe of fpecific gravity, took place; in others, neither of thefe effects was produced. The fpecimens which I had made were chiefly of the latter kind. Exp. 8. Cupellation did not afford any fatisfaflion refpe^t- ing the analyfis of palladium ; but the heat neceflary for this purpofe is fo great, that I could not place great reliance upon this experiment. It is difficult to detach the button from the cupel with accuracy. Exp, 7. I burned fome palladium In oxigen gas. A white fmoke arofe during the combuftion, and was depofited upon the fides of the glafs jar that contained the gas. But this fmoke was palladium, and not the mercufy feparated from it. Exp. 8. A flip of palladium, which Mr. Davy bad 4ho goodnefs to expofe, in my prefence, to the adtion of the ftroiig galvanic batteries of the Royal Inftitution, burned with a very vivid light, and a white fmoke ; but no mercury was feparated by this operation. . There is not any property of this compound which appears; to me fo wonderful, as that which is raanifefted by thefe ex- periments. It is a ftriking proof how unfounded was the opinion of fome philofophers, who fuppofed that the rapidity of combination was a meafure of the force of affinity. We do not know of any affinity among chemical bodies which is more powerful than that of platina and mercury appears to be. The obftacles which m\ift be overcome, in order to fix the latter metal, are a proof of this ; yet the difficulty of forming this combination to its full extent is extreme. The difference which exifts between the compound and its elements,. v\'hen merely mixed, either, in folution or othervvife, cannot be ! uis^-ar;. better tRETfeNDED NEW METAL; PALLADIUM. ^9 better exemplified than by comparing the refult of the 5th iynthetical experiment, with the difficulty of expelling mercury from the compound. I mud here obferve, that all the analytical experiments. The mercury . , , , , / -c could not be and many others, were made, by way ot companion, upon fcparated from the palladium I had bought, as well as upon that which I had the bought pal- made. But, although I had myfelf combined the mercury from'^ny"of the with theplatina, and confequently knew it to be in the com- author's real pound that refuked, I could not fucceed in feparating it. ^'>«»»'inationu Neither did the fubdance defcribed in a former paragraph, as intermediate between platina and palladium, allow one particle of mercury to efcape from it, by any procefs I have )^i been able to devife. The name of palladium conveys to our mind the idea of Objections to foraething abfolute, and therefore incapable of gradation. But ^.^jj°'^ ^* *' gradations in alloys are infinite ; and the alloy of platina and mercury is fufceptible of infinite variation. Palladium alfo brings to our recoJIeflion a contemptible fraud dire6led againft fcience ; the name, therefore, ftiould not be admitted. I have called it an alloy ; for it differs too much from the ufuai idea we have annexed to the word amalgam, but it accurately correfponds with our notions of the name I have adopted. The fads which I have related in this paper, appear at firft Thefe new fad* fight to have no fimilar examples in chemiftry ; and may not J^^j^g credit, gain immediate aflent from every perfon. The philofopher, indeed, will feel no humiliation in being forced to corred or to extend his knowledge; and will not altogether dilbelieve a fa6l, v becaufe he can adduce no parallel inftance, or becaufe it is not in unifon with his received opinions. Such condufl would be railing an infurmountable barrier againft the progrefs of fcience; it would be fetting up our own feelings in the place of nature ; 'and attempting to meafure what in itfelf is imraeafurable, by the narrow fcale of human comprehenfioH. But let us not confine our view of the fa6ts and principles that have been mentioned, to this lingle inftance. Let us trace them in a more extended circle ; and fee whether any thing may be found in nature that can apply to the prefent fubjed. The firfl prejudice, for fuch I mull call it, againft the pre- Theftraa^ fence of platina in palladium i?, the fmall denfity of the alloy, din^'^ution of . , , , . . , . , ,./..,; fpecinc gravity And no doubt it is extraordinary, that a metal the fpecific in this compound gravity of which is at lead 22, (Chabaneau fays 24,) com- muftnotpre- bined with another the fpecific gravity of which is nearly 14, ^"^ ***" * H 2 ihould 100 rRETENDED KEW METAL; PALLADIUM, fhould produce a mafs of the fpecific gravity of 10,972 ; not much more than half of that which calculation would denote. Other fimilar and inferior to either of its elements. In Mr. Hatchett's Pa- per upon the Alloys of Gold, to which I always refer with pleafure, we find fome extraordinary inftancesof anomalies in fpecific gravity, both in excefs and diminution upon the cal- culated mean. His experiments have not been doubted ; nor can their accuracy be called in queftion. The principle of de- viation in the true and the calculated mean is therefore ad- mitted. Who then can fay where this deviation Ihall end, or mark out limits to the operations of nature ? Particularly the But a no lefs extraordinary inflance of irregular denfity is difFerent Specific j^j, ^j^fy^e our eyes ; yet it has not fo much as attraaed our gravities of •/. t-,-.i/. , r gafifornr water attention. It IS true that it is taken from among the gafes, or fteamand a g^j^^ jf ^^ fuppofe that we have attained accuracy in experi- gafes which ments upon thefe fubjeds, I fee no reafon to refufe their evi- form it. Thefe dence in this inftancc. The denfity of oxygen gas, to that of arc as 7 4. ^j^fgj, jg ^^ | jq 740; and the denfity of hydrogen gas as J to 9792. The mean denfity of that proportion of oxygen and hydrogen gafes which confiitutes water, is to that of water as 1 to 2098; or, in other words, water is 2098 times heavier than the mean denfity of its elements in the gafeous fiate. But water is only 1200 times heavier than fleam, or water in the fiate of vapour. Therefore, there is a variation in -\-, of 898, or nearly half, between the denfity of water and its elements, when both are in the aeriform ftate. This fad, however, re- gards bodies only as they. remain in the fame ftate, whether of folidity, liquidity, or fluidity. The anomaly is mnch greater, if we contemplate them as they pafs from one of thefe ftates to the other. Yet we muft not omit the confideration of fuch a change, in the inftance of mercury alloyed with platina ; for the former metal, before liquid, becomes folid as it enters into the new combination. The fixation of ^ ftronger prejudice will perhaps exifl againft the fixation mercury is a fad of fo volatile a fubflance as mercury. It is certain that the inan*^others laboAirs of the alchemifis have thrown fome ridicule upon this and ought to fubjeft, as a philofophicial purfuil. Men of fcience have long excite no preju- fj,,(_.e declined the refearch ; and it is not probable that we are indebted to experiments undertaken in the true fpirit of phi- lofophy, for the prefent fixation of mercury. But, the fame caufe which induced us to look upon the projefl as chimerical,- 4 Ihould fRETENDED NEW METAL; PALLADIUM. fOl fliould difpofe us to admit it when accompli (lied. Every che- mift well knows that fimilar fixations of volatile fubftances are not uncommon If an ore containing fulphur, or arfenic, or antimony, be gently roafted, a great part of thofe volatile bo- dies is driven off; but, if a filling heat be fuddenly applied, Inftances; the the mafs unites in fuch e manner that a very fmall fliare of ^^jpi^^^^ arfenic, them efcapes. Mr. Hatchett has inftanced an artificial com- antimony. bination of gold and arfenic, from which he could not expel the latter metal, by any degree of heat. Yet arfenic, though lefs fufible, is not much lefs volatile than mercury, I will alfo add a cafe ftill more in point; viz. the combination of arfenic and platina, which is not to be broken by a fufing heat. An example of this fa6t, occurs again in water. The lique- Mercury havhig faction or folidification of two gafes to produce water, by a J.o^b?ieTJith lofs of caloric, never (hocks our mind, becaufe it is familiar to platina, may be us. We cannot fay what lofs of caloric may be fuftained by '" ^"^ *""^^ •^ . . ■' . ■' fituation as ox- mercury, in order to unite with platina ; or how far the pre- ygen jn many fence of the latter may contribute to expel caloric from the oxides; viz. not former. We know too, that at any temperature, without the ^^^^ ^eat, and aid of a combuftible body, to a6l as a reductive, we have not perhaps by few been able to difunite the laft portions of oxygen, from the ^ oxides of iron or of manganefe. Yet, in the ufual method of ' reducing a metallic oxide, the oxygen is furrounded by a much greater quantity of caloric than is necelTary to convert it into gas. Every fixation of a volatile fubftance is analogous to the prefent queftion; and they whofe minds have taken alarm ' from the novelty of the fa6l, may thus be familiarized with the neceflity of admitting it. But, it may be obje6led, in the inftances of iron or manga- Metals may nefe, oxygen is combined with a combuftible body, and re- <^ombine toge- . , • . 1 1-11 1 ri ^ • r^, . therbyanaffi- tamed m it by a decided and powertul affinity. There is no nity comparable reafon to fuppofe that fuch an affinity may not exift among *° ^^^^ °' ^ metals. We have been forced to acknowledge it, in a few gen, cafes, among the earths; and, from the profound and faga- cious refearches of Mr. BerthoUet, we have learned many new fa6ls, that promife us a rapid increafe of knowledge. I (hall beg leave to add a few examples, which are taken from that clafs of bodies to which the fubje6t of the prefent Paper be- longs, and (how that the metals obey the general law of mu- tual attra6tion. CTo be concluded in our next.) 102 INVESTI8ATI0H OF CIRTAIN THEOREMS No complete re fults have yet been had as to the figure and Snumer&tion. III. Jnvejligation of certain Theorems relating to the Figure of the Earth . By ]ofin ?LAYFAiK, F. R. S. Edin. and Profejfbr of Mathematics in the Univerfity of Edinburgh. ♦ 1. 1 HE obfervations which have been made to determine the magnitude and figure of the earth, have not hitherto led to refults completely fatisfadlory. They have indeed demon- magnitude of the ftrated the compreflion or oblatenefs of the terreftrial fperoid, but they have left an uncertainty as to the quantity of that comprelfion, extending from about the one hundred and feven- tieth, to the three hundred and thirtieth part of the radius of the equator. Between thefe two quantities, the former of which is nearly double of the latter, mod of the refults are placed, but in fuch a manner that thofe beft entitled to credit are much nearer to the leaft extreme than to the greateft. Sir Ifaac Newton, as is well known, fuppofing the earth to be of uniform denlity, atfigned for the compreflion at the poles ^j-^, nearly a mean between the two limits juft mentioned ; and it is probable, that, if the compreflion is lefs than this, it is owing to the increafe of the denfity towards the centre. Bofcovich, taking a mean from all the meafures of degrees, fo as to make the pofitive and negative errors equal, found the difference of the axes of the meridian = yj^. By comparing the degrees xneafured by Father Leifganig in Germany, with eight others that have been meafured in different latitudes. La Lande finds YTT, and, fupprefling the degree in Lapland, which appears to err in excefs, jjy ^^^ the compreflion. La Place makes it Sejour y^y, and, laftly, Carouge and La Lande y^-^. Thefe refults, which reduce the eccentricity of the meridians fo much lower than was once fuppofed, agree well with the obfervations of the length of the pendulum made in different latitudes. Were the earth a homogeneous body. Sir Ifaac Newton demonftrated, that the diminution of gravity undet the equator would be = ^TZt expreffed by the fame fraftion with the comprefCon at the poles. M. Clairault made after- wards a very important addition to this theorem : for ^le ihewed, that, if the earth be not homogeneous, but have a The refults of obfervcd eccen- tricity agree with the com- puiarions de- duced from the length of the fecond^ pendu- lum. ♦ Edinburgh Tranf. Vol. V. denfity ti%UAXtVa TO, THE T.IGTJilE O^, THE KARTH. 103 denfity that varies with any fundlion of the diftance from the centre, the two fraftions, expreffing the compreflion at the poles, and the diminution of gravity at the equator, when added together, muft be of the fame amount as in the homo- geneous fpheroid, that is, muft be = ^^ or -j-tt- Now, the fecond pendulum is conceded, from tlie beft and moft recent obfervations, to be longer at the pole than at the equator by T-ly, and this, taken from -j-jy, leaves y^^ for the compreHion at the poles. 2. But though t4-s, or fome fra6tion not very different from Why have not , , , °, . , , -, , , , , ,. ., the obfervations it, (hould be admitted as the moft probable value of the com- ^^ ^^^^ agreed predion, or ellipticity, as it is called, of the terreftrial fphe- better ? roid, it ftill remains to be explained, why all the obfervations^ "Confidering the care with which they have been made, do not agree more nearly with this conclufion. Among the cau(es ^ that may be affigned for this inconfiftency, though unavoidable ' miftakes, and the imperfection of inftruments, muft come in 'for a part, there can be little doubt that local irregularities in Uhe direction of gravity have had the greateft fliare in producing 'it. Of thefe irregularities, that which arifes from the attrac- Anf.— Prind- "tion of mountains has had its exiftence proved, and its quan- gt-raafon" V * ttity, in one cafe, afcertained, by the very accurate obferva- mountains have. *tionsof th« prefent aftronom«r-royal at Schehallien in Perth- jjg^^f."f°thr "(liire. We may trace the operation of this caufe ia many of plumb-line, 'the degrees that have been adtually meafiired. Thu??^ in the ''degree at Turin, when^ divided into two parts, and each efti- 'mated feparately, that which was to the north of the city, and * pointed toward Monte Rofa, the fecond of the Alps in efeva- } ""'tion, and the firft perhaps in magnitude, was found greatef in ^■'* proportion than that toward the fouth, the plummet having been attracted by the mountain above mentioned, and the ^ze- , iiith made of confequence to recede toward the fouth. There » ^are no doubt lituations in which the meafurement of a fmall air<^ might, from a fimilar caufe, give the radius of curvature of the meridian infinite, or even negative. But there is another kind of local irregularity in the dIre6tion Another more of gravity, that may alfo have had a great effea in difturbipg ^J'J"^'*^?'* ""^* the accuracy of the meafurement of degrees. The irregularity I mean is onearifing from the unequal denfity of the materials under and not far from the furface of the earth ; and this caufe of error is formidable, not only becaufe it may go to a great extent, 10^ INVESTIGATION 0¥ CERTAIN THEOREMS extent, but becaufe there is not any vilible mark by which its that the denfity exiftence can always be dillinguilhed. The difference be- °ear^th^"rth*s tween the primary and fecondary ftrata is probably one of the fuiface muft be chief circumftances on which this inequality depends. The "^" j^ greater to- primary ftrata, efpeclally if we include among them the granite, gionsthan ^^X often have three times the fpecific gravity of water, others, whereas the fecondary, fuch as the marly and argillaceous, frequently have not more than twice the fpecific gravity of that fluid. Suppofe, then, that a degree is meafured in a country where the ftrata are all fecondary, and happens to ter- minate near the junction of thefe with the primitive or denfer flrata, the line of which junction we (hall fuppofe to lie neaiiy eaft and weft; the fuperior attraction of the denfer ftrata muft draw the plummet toward them, and make the zenith retire in the oppofite diredtion ; thus diminiftiing the amplitude of the celeftial arch, and increafing, of confequence, the geode- Thls error may tical meafure affigned to a degree. From fuppofitions, no feconds*"^'^^^* way improbable, concerning the denlity and extent of fuch mafles of ftrata, I have found, that the errors, thus produced, may eafily amount to ten or twelve feconds. Accurate refults 3. While we continue to draw our conclufions, about the are therefore figure of the earth, from the meafurement of fingle degrees, onlvtobehad ° ' „ . ,. * ^ ,. ° .^ from large arcj j there appears to be no way ot avoidmg, or even oi diminitn- ing, the effeCls of thefe errors. But if the arches meafured are large, and confift each of feveral degrees, though there (hould be the fame error in determining their celeftial ampli- tudes, the effect of that error, with refpefl to the magnitude and figure of the earth, will become inconfiderable, being fpread out over a greater interval ; and it is, therefore, by the comparifon of two fuch arches that the moft accurate refult and thefe require is likely to be obtained. But, in purfuing this method, fince new modes of ^\^q arches meafured cannot be treated as fmall quantities, or computation. ^ . . . ,,. r iii- mere fluxions or the earth s circumference, the calculation muft be made by rules quite different from thofe that have been hitherto employed. Thefe new rules are deduced from the following analyfis. InTcftigatlon of 4. Let the ellipfis ADBE reprefent a meridian pafling formulab for through the poles D and E, and cutting the equator in figursofthc A and B. Let C be the centre of the earth, AC, the tutth, radius of the equator, = a, and DC, half the polar axis, = b. Let FG be any very fmall arch of the meridian, having its RELATING TO THE FIGURE Ct THE EARTH. 105 its centre of curvatulre in H ; join HF, HG cutting AC in Inveftlgation of K and L. Let (p be the meafure of the latitude of F, or the ^"'"""'f.' ^' ^ ' computing the meafure of the angle AKF, exprefled, not in degrees and figure of the minutes, but in decimals of the radius 1 ; then the excefs of "'^*' the angle ALG above AKF, that is, the angle LHK or GHF will be = )» fin*?!) *, as is demonfirated in the conic feftions. There- fore, if c be the compreffion at the poles, or the excefs of a above b, b^ =za* — 2ac + c*, or becaufe c is fmall in com- parifon of o, if we rejed its powers higher than the firft, i* == a* — 2«c,and FH = a» {a — 2c) (a^ — a^ fin »(?> -f a' fin* (p — 2ac fin 2?>) ^ = a^ (a - 2c) (a* - 2ac fia »?») ** 3 q Qc 3 But (a^ - 2ac fin «^) "Z" = a "^ (1 fin «?)) * a = a ■ (1 -}- — fin *^) nearly, rejeding, as before, the 3c terms that involve c*, &c. Hence FH = (a — 2c) (1 -| fin •?>) = a - 2c -f 3c fin 2^. Now 10^ INVESTICATIOKOF CEETAIN THEOREMS Inveftigabon o' *r •*__,-* • formulas for -Now 2 =

figure of the = (a - 2c)

by rejeding thofe terms that are fmall in corapari- on of the reil, v =z --— — ^, and d(nm~-nm ) ^W^ (g'm — gm) d(n'm — nm'y Thus 27 and m are found, and of confequence d-^-v and h-^-u, that is a and c, without negleding any terms that aie not of an order lefs than ; and when it is conlidered that a £l a — is lefs than , it will readily be allowed that it is quite a 22500 ^ ^ unneceflary to carry the approximation farther. 4 Jl.The fame thing that renders the comparifon of large The errors of arches of the meridian ufeful for leflening the effeft of errors obferyation ire • ^ r ■ ,....,. ^. r •, 1 .lefs the larger arifing from irregularities m the direction of gravity, makes it t^g grcg, ferve to diminifti the effe6l of all the errors of the aftronomical obfervalions at the extremities of the arches, from whatever caufe they arife. They are all difFufed over a greater interval/ and have an effefl proportionally lefs in diminifhing the accu- racy of the laft conclufion. 12. The meafurement therefore of large arches of the meri- Extenfive fur- dian, efpecially if performed in diftant countries, is likely to ^^ys particularly furnilh the bell data for afcertaining the true figure of the earth ; and on this account extenfive and accurate furveys, fuch as that above mentioned, are no lefs interefting to fcience, in general, than conducive to national utility. The furvey of this ifland, when completed, will furniQi an arch of the meri- dian, beginning at the fame parallel where that meafured in France terminates, and nearly of the fame extent, fo that the length of an arch of more than 16**, or almoft a twentieth of the earth's circumference, will become known. Theditferent portions of this arch compared with one another, or with the V - arch 110 INVESTIGATION OP CERTAIN THEOREM* arch meafured in Peru, will afford a variety of data for deter- mining the true figure of the earth. Obfervations of But furveys of the kind now referred to, afford likewife tTSL^meridian ^^^®'* "^^^er'a's ^roi" which the folution of this great geogra* and of parallels phical problem may be deduced. Thefe are chiefly of two of latitude. fo^ts^ viz. the magnitude of arches, either of the curves per- pendicular to the meridian, or of the circles parallel to the equator. Examples of the firft of thele have been given by General Roy and Mr. Dalby ; the obfervations which follow are directed toward both. Large perpcndi- 13. With refped to the meafurement of arches perpendicu- veilj'difficuk ^^^ ^^ ^^® meridian, it may be obferved, that the direaions of meafurement J gravity at different points of fuch arches do not interfedt one another at all, unlefs the diftances of thofe points from the faid meridian be very fmall. On this account the meafurement of a large arch perpendicular to the meridian would involve in it confiderable difliculty ; to avoid which it is neceffary that the arch meafured be but fmall, or one that does not greatly ex- and fmall ones ceed a fingle degree. Such meafurements are of courfe ob- erroneous from noxious to all the errors that arife from the deflexion of the partial gravjta- , , , . r • i r ^ tion. plumb-lme, and cannot therefore furnilh data for determining the figure of the earth, equally valuable with thofe which may be derived from large arches of the meridian. The method of determining the figure of the earth, from degrees of the perpendicular to the meridian, is not however without its ad- vantages, and in certain circumftances is preferable to any other that proceeds by the meafurement of arches equally fmall. This method is twofold ; as a degree of the meridian may be compared with a degree of the perpendicular to it in the fame latitude ; or two degrees perpendicular to the meri- dian, in different latitudes, may be compared with one an- other. The advantages peculiar to each will appear from the following inveftigalion. To find the axes ^^' Let It be required to find the axes of an elliptical fphe- of a fphcroid roid, from comparing a degree of the meridian in any latitude a2cg."rth"°^ ^'^^ ^ degree of the curve perpendicular to the meridian in merid. with one the fame latitude. of the perpend. Let theellipfis ADBE (Fig. on page 105) reprefent a meri- dian, of which a degree is meafured at F. Let the perpen- dicular RELATING TO THE FIGURE OF THE EARTH. Ill dicular to the meridian in F meet the lefs axis DE in R. Then T« find the axe» R will be the centre of curvature of the circle cutting the me- f ^ fphcroid . . irom comparing ridian at right angles in F ; for at any point in that circle mde- a deg, of the ^ finitely near to F, the diredion of the plumb-line, or of gra- "J^rid. with on* vity, as it always pafles through the axis DE, will cut DE in R ; it will therefore alfo interfed FR in R, fo that R is the centre, and FR the radius, of curvature of the perpendicular to the meridian. Let H be the centre of curvature of the meridian itfelf at F : draw FO perpendicular to DE, and let the latitude of F, or the angle OFR = q>. Alfo let AC = a, CD =:bf and a — b =€, as before. Then from the nature of the elliplis, FO = ''*^''^^ and becaufe fin FRO : 1 : : FO : FR, v^a» cof *(p -f b"- fin ^* that is, cof ?) : 1 : : FO : FR, FR =• ^a* cof »cp -f- b"- fin ' a* . c* b^ FR : FH : : i* j. (a* cof ^* -1- 6* fin * + 6* fin 9*)» and dividing both by — r- 1. we have (a*cof* -f b* fin * «* f^» . r «.. u «^-. I-TY ^ = IT cof ?>* + fin *^. Hence D -^"'^'. cof ^ This laft formula, therefore, gives the ratio of a to i when D, D' and if we aim only at an approximation, which ihde^d is all that is neceflary in this inquiry. Since c denotes the compreffion, or fmce a-^czzh, and therefore a^ — 2aCZZ b^ nearly, confe- quently the radius of curvature of the meridian at F, that is j^ _ g^ (q^ — 2ac) a^ (a—Qc) (a^ — 2ac fin <|)*)* aM I — -^ fin (p^)^ ^ a Sc (a — 2(^) (1 — ^— ' fin *. From thefe equations we obtain, rejecting always the higher powers of c, C =. — ^ i, a = mD' i— —^ — —_ ; and 2cof(2)* 2 cof 9^ c D' — D « 2D' cof being — 30^ 41^ From this — zr D'— D 331 1 which 2D'cor»cp ■" 2x61 182 X (cof 50"* 41/)* "^ 148.4 is nearly the fame refult with that deduced fn tlfie paflage juft referred to. Indeed the folution of this problem, contained iil the Trigonometrical Siirveif, is quite unexceptionable ; and the theorems here offered are not given as containing a more accurate folution, but one that is in fome refpedls more fimplej Whether the The al>bve compreflion, if qy© remarks already made be well rnagnitudc of founded, is much too great, being mor6 than double of what prcve an irrcgu- was obtain^ from comparing the whole arch of the meridian lit figure. meafurei in Frai)cevvith the whole of that meafured in Peru. At' the fame tune, it is right to obfeirve, that all the other eom- parifons of the degrees of the meridian, with tliofe of the curve perpendicular to ifc, ifiade frotii the obfervations in the fouth of England, agree nearly in giving the fame oblatenefs to the terreftrial spheroid. For this circumflancci it is cer- tainly not eajy to account; the unparalleled accuracy with ivbich^Ke' S^noie of the m^afurement has been condudled, makes it in the higlie^ degree improbable that it arifes from any *-tror ; and eve» if errors were to be admitted, it is not iikely that they fliOuld all fall on the fame fide. The authors of the TrigdinomeiTical Survey feem willing, therefore, to give Mp the elliptic figure of the earth, (Ibid. p. 527); but before we abandon that very natural and fimple hypodiefis, it may perhaps be wortli vvhile to attend to the following confi- dtrations, 20 tlfitATING to THE FIGURE OF THE EARTH. jfjl '20. In the part of England, where the meafures we are now Obfervations to treating of have been taken, theftrataare of chalky and though irregularity pro'- of great extent, are bordered, on all the fides that we halve bablyarlfes from accefs to examine^ by ftrata much denfer and more compad. ft^ncesT""*" Toward the weft the chalk is fucceeded by limeftone, ftnd that limeftone by the primitive fchiftus and granite of the weft of Devonlhire and of Cornwall. On the eaft we may fuppofe that fomething of the fame kind takes place, though the fea prevents us from obfervihg it, as the chalky and argillaceous beds extend in this diredtion to the coaft, and probably to fome diftance beyond it. Now the meridian of Greenvvich The merldlaa of may be confidered as dividing the trad of country, occupied ^''*^^"^'^'? ?P* J » ^ J ' t pears to divide a by thefe lighter ftrata, into two parts, in fuch a manner, that- chalk country, the plummet being carried to a diftance from it, either eaft or ^^f ■"& on each welt, approaches to the denier ftrata, and is ot courle attracted ib-ata of lime- by them, fo that the zenith is forced back, as it were, to the ^""^j fchiftus, meridian of Greenwich, and does not recede from it, in the which^Ty^at- heavens, at fo great a rate as the plummet itfelf does, on trading the the earth. Hence the longitudes from this meridian, eftimated li^^^ wav^out- by the arches in the heavens, intercepted between the zenith wards, muft re- and the faid meridian, will appear lefs than they ought to do ; ^j"^^ * longer and too much fpace on the furface of the earth will of confe- ingorwefting to quence be afljgned as the meafure of a degree. In this way correfpond with D' is made too great ; and we may fuppofe the circurhftances igftjai arc. fuch that D, on going north or fouth, h not enlarged in the jy D . fame proportion; hence ■ will be augmented, and of (^ courfe - will be reprefented as too great. This explanation a may perhaps appear very hypothetical, and it is certainly pro- pofed merely as a hypothefis. It is a hypothefis, too, that lays claim only to a temporary indulgence, as it is propofed at the very moment when it may be brought to the trial, and when, by a further continuation of the furvey toward the-jiorth, it will probably be determined how far the diftribution of the ftrata of this country affeds the direflion of gravity. It will indeed be curious to remark what irregularities take place on advancing into the denfer ftrata of the north. The limeftone. and fandftone ftrata of the middle part of the iftand will fucceed^ to the chalk of the fouth, the primitive and denfer ftrata ftill ' I 2 occupying 116 LEUSTH OF THE SOLAR YEA3.. occupying the weft, at leaft at intervals, as in Wales, CaiU* ' berland, and Galloway. Further to the north, that is, beyond theTay, the ftrata became entirely primitive, mofl of them of the denfeft kind, and in the interior of the ifland, with a very few cxeptions, continue the fame to its moft northern extre- mity. In the furvey of Britain, therefore, feveral fituations inuft occur where the plummet, pafliiig from lighter to denfer ftrata, ought to give indications of fome irregularities in the direction of tlie gravitating force. It will be feen hereaftet how far thefe conjedures are verified by experience. (To he continued,) IV. On the Determination of the Length of the Solar Year, By Mr, R. Winter. Red Crofs tVharf, London-Bridge, 13th Jan. 1804. To Mr. NICHOLSON, SIR, Determination ^HOULD you confider the following communication as de- of the length of ferving a place in your valuable Journal, by inferting it you Adual years. Will obhge \,, Your's, &c. R. WINTER. To determine the precife length of the Solar Year is an ob- je6l of primary utility in aftronomy, as being the bafis for af- <;ertaining the periods of all the moving bodies in the univerfe. , Various and accurate methods have been given for deter- mining this period; but as the following unites fimplicity, to the advanced ftate of fcience, thefe chara6lers may render it worthy of your con fi deration. Given, the time and place of the fun in the ecliptic, and the time of its returning to the fame place; the obliquity of the ' ecliptic for the prefent time, together with the decreafe there- of, ptjr year, to find the length of the folar year. According to Ptolemy, the place of the fun was Sagittarius i^o 22' 50'^ anno. 130, Dec. l^th. 11^' 3S»* 40- (reduced to the ^EW METAL IN CRUDE PLATINA, &C. 117 the meridian of London,) its return to that place in 180t ac- cording to Mayers tables improved, is Dec. 13th. 0^- 19™- 36* the interval, (allowing for bifTextiles, &c.) is 6114.16"- 12*^ 40'"* 56** which divided by 1674, the number of years, gives 365^- 5^'49'^' 42" Now the obliquity of the ecliptic, as ob- ferved by Caffini in 1655, and Flamftead in 1689, being com- pared with that obferved by Horn{by in 1772, Mafkelyne in 1769, Bradley in 1750, and Mayer in 1756, and a mean of their obfervations taken, will give for the decreafe of the ob- liquity of the ecliptic 59'' per century, or 35 ^'^4. per year. Ac- cording to thefe calculations the obliquity of the ecliptic for 1 804 will be about 23^ 27 '49''; then as the fun moves over this fpace in one quarter of a year, fay as 23° 27' 49" is to J of the given year, fo is the decreafe of the obliquity of the ecliptic* per year 35'''4 unto 55^\ which taken from 365°' 5^' 49"* 42* gives for the length of the folar year 365°' 5^- 48'"' 47'- and the time the fun moves over the proceffion of the equinoxes is 20 minutes 27 feconds, which being added to the folar year will give 365°' 6^- 9". 14" for the length of the fidereal year. But by afluming I of the year thus found, and working as before, it will give the length of the year more accurately. V. ExtraSis from a Letter of R. Chenevix, Efq. P. R. S. from Drefden, to Charles Hatchett, Efq. F, R, S. containing Infor^ mation refpe^ing the new Metal contained in Crude Flatina ; Beet Sugar ; the non-exiftence of Agvjlile as a peculiar Earth; and a Defcription of a new Furnace for Chemical Operations, Cofumunicaied by C. Hatchktt, Efq, I SUPPOSE you have heard of the new metal contained in New metal In cruce platuii* raw platma. Here is what Berthollet has jult written to me upon the fubjed : <* Des Coftils diffblves raw platina in nitro-muriatic acid, and precipitates it by muriate of ammonia at feveral times; the firft portions are yellow, the laft redder. He reduces the red precipitate, and obtains an alloy. He expofes this alloy to a current of oxygen, and a blue oxide is volatilizedj pure platina remains behind. The blue fublimate is the oxide of his new 118 N?W »f:ETAL JN CRUpE PLATIKA, &e. new metal; on the fame day Fourcroy and Vauquelin read their paper at the Inftitute, ^nd mentioned fjmilar experir paents.'* Palladium affert- Van JVIons writes me word that at Paris they Tay that it is of the ncwmetal^'^*- P^^^'^^^i* ^^^ ^^^is new metal, which with mercury compofes with iperwiy. palladium; but that has very little to fay to the purpofe, for the lingular thing in palladium is, nof what regards platina, but jwr'hat regards mercury, and the fufibility of the combination. ,J3efides there muft have been platina in my palladium, as I 400k the metal reduced fron) the red and yellovy falts indifcri. J ^inately. M»nufaaure of Lanlpadlus tells me that he has made feveral hundred weight Um^Xs^^ of fugar from the red beet ; but the manufadory he eftablifhed has failed. It coil him within two gros per lb. as much as the common fugar of equal quality, but then he had a refiduum fit Tor fermentation, which was clear profit. Aguftlte IS i had made fpme progrefs in the analyijs of the Saxon beryl, inerely phof. when I received a letter fron> Berthollet, in which he told me ^ * that Vauquelin had found the aguftite to be nothing more than phofphate of lime. I continued my experiments however, and obtained the following refults. Having boiled muriatic acid upon the pi^lveri^ed mafs which contains the Saxon beryl. Muriatic folu- 1 obtained a folution of the pretended agurtjte. I precipitated tioaof Saxon ^^y ammonia, and, upon examining the precipitate, found it amm. gave phof."' ^o be phofpbate of lime. To have no doubt as to the phofpho- of lime. This .rJQ. acid, I treated 1500 grains of this prepipitate with half by fulph. acirt^ ^*'-^ weight of fulphuric acid, walhed the mafs, and evaporated and the purified to drynefs. I re-diflolved as much as was foluble in diftilled reduced w ac • '^^^^^^» ^"^ faturated the liquor by ammonia. By evaporating t«al phoiphorus. once more, I obtained phofphate of ammonia, which I de- compofed at a ilrong red heat, and obtained phpfphofic acid, which gave no trace of fulphuric or any other acid, or of any dearth, alkali, or metal. I mixed this with pounded charcoal, and by diftillation in a ftrong fire obtained a confiderable quan^ ' tity of phofphorus. Thus then the fimple earth of Mons- I'rDfnfdorf is^ phofphate' of lime. I havQ NEW METAL IN CRUDS ?LA,T.XNA, &C, ^19 1 have conftru6ied a wind furnace here, which is in fotne re- Chemical fur- fpeds to be preferred to the ufual form. The fides, inftead of of acone, nar- being per'pendiciiIar,areinverted,ro that the hollowfpace is py- roweft above. •J- t A. XT- J.. 1 • • r- ■ , r Its g.eat advatt- ramidical. At the bottom the openmg is thirteen inches Iquare, tage is that the and at the top but eight. The per- fueldefcends pendicular height is 17 inches, o^^f^jring* ^^ This form appears to me to unite the following advantages. Jft. A great furface is expofed to the air • which, having an eafy entrance, rufhea through the fuel with great rapidity. 2d. The inclined fides aft in fome meafure as re verberating furfaces: And 3d. The fuel falls of itfelf, and is always in clofe con- tact with the crucible, placed near - the grate. This I believe to be the principal advantage. The ' late Dr. Kennedy of Edinburgh, whofe opinion on this fubje£t claims the greateft weight, found that the firongefi heat in our .common wind furnaces was within two or three inches of the ^rate. That therefore is the moft advantageous pofition for >; the crucible, and dill more fo when we can keep it furrounded ^with fuel. It is inconvenient and dangerous for the crucible j ';^lo flir the fire often to make the fuel fall, and the pyramidical reform renders this unneceflary. It is al(b more ea(y to avoid a fudden bend in the chimney by the upper part of the furnace advancing as in this conftrudion. a is a grate; c and c are two bricks, which I can let in at pleafure to dirainifh the ca- pacity ; b is another grate, which I can place upon the bricks c and c for fmaller purpofes ; d and d are bricks which I can place upon the grate b to diminifti the upper capacity, fo that in fad I have four different fizes in the fame furnace. I have had forae very ftrong fires in ufing the whole capacity from the grate a to the top e without the bricks c and c ; but I am at a lofs for our good Englifli coaks. The bricks have all been ground down to the flope of the furnace and fit in with toler# able accuracy. They are totally independent of the pyramid dical form, &i.c, of the furnace. 4ii99unt- 120 DAMASCUS SWORD BLADES, VI. Account of an E3peri7neTit to imitate the Darnqfcus Suord Bla^ei:^ In a Letter from Mr. James St odart. To Mr. NICHOLSON, Dear Sir, On ^vord blades O AVI NG lately had an opportunity of examining fomo in general. fword blades, which appeared to bedefeftive, I was induced Quality too . i r ,i . . rr.t r i • rw • r i r often defe^ive. ^^ make the following experiment, j he lubject is lurely ot fome importance, and perhaps never more fo than at the pre- fent moment. We hear of fwords having broken in battle, and we can hardly imagine a more diftreffing circumftance, Thofe which I have feen are certainly in no danger of failing in that way, for on the contrary they ar^ evidently too foft, and confequently cannot form a good cutting edge. I am not ac^ quainted with the procefs ufed in making fword blades, but ^m inclined to fufped that the price allowed is not equal to Experiment. the labour necefTary to form a good inftrument. The following Steel and iron ^jethod, which I believe to be nearly the fame as that pradifed bars were welded ^ - , y • ^ t r r ^ iii ^•r,- i t together, at Damalcus, but which 1 lulpecl would be too difiicult and expenfive for general application, may perhaps lead to fome more fimple method of accompli filing the defired purpofe. I took fix fmall ba/sofgood malleable iron, and the fame number of ftieer fleel, and laid them one on another alternately, as if forming a galvanic pile; I then with the afliflance of an expert workman, committed them to a clean forge fire, and with Forged out, care we fucceeded in welding them into a folid lump. This was forged into a ilout flat plate, which being heated to white- Twifted, flat- nefs, was by means of llrong tongs tvvified fpirally until it tencd, ■ii^\n formed a cylindrical tube. In this twifled (late it was heated, mercd flat. ' hammered flat, and again welded, and after being forged into a convenient form and fubflance, was doubled throughout its whole length, fomcwh^it in ihe manner of (he back of a faw. An edge of ftcel ^ flip of good fteel was inferted, and another welding heat a baclToMhe"''" taken, which confolidated the whole mafs. I need not fay compound, this flip of fleel was intended for our edge. The remaining part of the procefs was Ample; it conflfted only in forging it into the fliape of the blade we wanted; which on examination proved perfectly found in every part. Being eager to witnefs foHjc proofs pf excellence and beauty which my expectation PAMASCUS SWORD BLADES, 121 had anticipated, I too haflily and without due confideralion proceeded to harden it by heating and quenching in water; 3nd had ihe misforlune to fee it cracking in feven or eight dif- Itcrac'ced la ierent places. I have no doubt this wasoccafioned by the un- ^^ "*'"S' equal expanfion and fubfequent contraclion of the different parts of the mafs, Jn ray next trial I fhall guard againft this accident. Enough however remained found to prove it both ^— but promifei good and beautiful; the edge bears the fever eft trials at the "'^^l* lame time that the whole blade has fufficient tenacity. I have poli filed a part of it, and by applying a weak acid, produced an appearance, which though by no means equal to the beauty of what is called the Daniafcus water, leaves me little reafon The Damafcua to doubt of accompliflung that appearance in my next trial, "^^f"* My intention is to multiply my pieces of metal, to repeat the procefs of tvvifting, and certainly not again to quench in wafer. I (hall take the liberty to tranfmit to you an exact account of ipy next experiment, and if fuccefsful, to accompany it with a fample of the metal formed into a blade of fome kind or an* pther. I am with much refped, ' - " Dear Sir, Your obedient fervant, J. STOPART. Prand,Jan, 19///, 1804. '.., P. S. Why is the appearance produced on Damafcus fteel Inquiries con^ by the application of an acid called the water? Is it not dif- """""'S the , 1 r • I • ^ jt 1 1 • t -11/^- , Damafcus watcf jerent degrees or oxidation ? * and what is the acid belt fitted upon fteel, to produce this appearance. I had a paper given me fome ten years ago on this fubjed, by a gentleman whofe name I do not know. Unfortunately I have miflaid it. In addition to what you have publiflied on the fubject in your valuable Journal, pray furnifii us with any other facts that may have come to'your knowledge fince that period. The fiibjecl; appears to me to be worthy of philofophical refearch, and perhaps of national encouragement. * I have always fuppofed fteel to be lefs readily foluble than pure iron; and that the carbon which is feen on the face of the former dpring the procefs of darnatking, defends it from the acid, while the fibres of iron are etched by corrofion fo as \o exhibit the peculiar vaving lines of this operation, N< leiUr J22 EFFECTS OF THUNDER. VII. tetter from a Correfpondent on the Efftdis of Thunder onfermenU ing Liquids; the Chemical A6iion of Sound, and Tremulous , Motiom, xvith otlwr Obfervations, NexLcajlle, Dec, 16, 1803. To Mr. NICHOLSON. SIR, l^ONVERSATION is certainly one of the moft defirable means for the increafe and diffemination of knowledge, what- ever defcription it may be of, and if the following remarks, urifing from an accidental convcrfation with a fcientific friend, be not altogether unworthy of your notice, you may make what ufeof them you think proper; and if thought worthy of being prefented to the public, you are at liberty to make any iiecelTary alteration in the flile that will render them more wor- thy of the honour I folicit. Changes pro- ^^ ^^^ h^QVi obferved, fo often indeed,' that it has almoft be- riuccd in beer conae a popular remark, that the noife of thunder produces a thunder^^*'" fiirprifing change on beer, and on cream; the firft becoming four, and the latl rancid, when they are agitated by this extra- Suppofed pre- Ordinary found. It has alfo been obferved, I believe, that the ventative re- effects of thunder on malt liquors maybe prevented by laying ^^'^^)* a cord over the calk, at each end of which, a flone, or other hard and ponderous fubftance is fufpended and kept in contact with theoutfide of the veflel containing the liquid liable to be affedcd by this kind of noife. The efFea fup. Now we may be able to form forae judgment of the manner poied to arife in which thefe liquids are afiefled, by attending to the tremu- 1^11^°^"°"'' lous motion produced on thofe glafles called linging and mufi- . calglafTes, when the furface of the firft is agitated by the breath; ^ and the liquid in the laft by the vibration produced by the finger drawn along the rim of the glafs, which varies in its tone in proportion to the quantity of liquid it contains. In the courfe> of the tone or found, if the glafs be prefled with the finger, the found either ceafes or is confiderably diminithed, and upon ap-r plication of the finger at the commencement of the found it will be evidently felt that both the glafs and the liquid are in a Hate of agitation, and that this agitation ceafes or flops when the agitated body is touched by anpther in a quiefcent Hate. Thil JEFPECTS OF THUNDBE. ' 123 This tremor, fo communicated, may in my opinion be the Which may pro- commencement of that inlenfible or rather imperceptible agi- j^enclmentof lation neceffary to the produftion of the different fiates of fer- the fermenutrrc mentation, which when once began, may be corjiinued, pro- ^g'tation. vided the circumftances of temperature, &c. be equally fa- vourable as atfirlL Now we perceive that this motion ispro^ duced by found;* and a fonorous body lofes this vibration on being touched, and the found itfelf of courfe ceafes. In like manner the inteftine niotion arifing from the vibration occafion- ^d by the noife of thunder, being prevented from taking place ,)by the conta6t of the fufpended Itones with the fides of the ; /cafk, the enfuing fermentation cannot commence, and the beer ^is preferved from running into the acetous fermentation. This infenfible motion is alfo neceflary to affift the abforb- ^ jtion of oxygen, without which neither beer can grow four, ^ nor can cream become rancid ; for violent agitation will not produce the like effed even though accompanied or affifted • yvith the neceifary increafe of temperature. It was alfo obferved by the gentleman with \yhom I was con- Decompofition yerfing on this fubjecl, that butter by being overmuch waflied of water or ay: or wrought in water Ipfes cpnfiderably of its yellow colour, and acquires in a great meafure the palenefs and confidence of tallow. It might be worth while to ipake fome experiments in this way, how far animal oils or fat are capable pf decom- pofing atmofpheric air or water. The circumftances jiecef- fary to determine Ihe mutual change on each, are agitation, and a frequent change of furface. The abforption of oxygen would takp place in both cafes, the refiduum of atmofpheric air being azotic gas, and that of water hydrogen gas. I had found by experiments, and that fome time before I favv the circumftance publicly noticed, I may fay, even before the new theory of chemiftry was promulgated, that the union between Rancid oils com« piercury and the fat with which it was combined in the com- ^'"<= ^®"«*" W'lJ^ pofition of the ointment, became much more intimate and ^efli"'^ perfed on being kept for fome time, and that the rancidity, which I thought arofe from the developement of fome peculiar acid, was prevented from becoming fenfible by that acid being abforbed by the metal. From thispircumftanpe, and from this fuppofition, I was Jpd contrary to the diredions and cqmmands f J mean among other caufcs producing it. of J24< EI,ECTRICAL MACHINE. oF the Royal College of Phyficians, to ufe a little rancid fat or oil, in order lo facilitate my labour and favour my indolence, and I was agreeably furprifed at ray fuccefs. The College order the pureft and fweeteft fat to be ufed; neverthelefs the utmoil diligence and care in rubbing the mercury with it does wot produce fuch an accurate combination at firft as is accom- pli (hed, after being fet by for a week or two, and this my be made evident by comparing two fpecimens of ointment made . with equal care and diligence, the one being quite recently finilhed, and the other having afterwards been kept undifturbed for two or three weeks. — I merely offer thefe hints for the con- (ideration of wifer heads than mine, and fliould they with this view be honoured with a place in your valuable repofitory, your ijidulgence will be moll refpeflfully acknowledged by Sir, Yours, &c, NORTHUMBRIENSJS. VIII. JmproT^mcnt of the EliciricalMaddnef chiejfj/mih refpe6t to ijie Rubbers; by Mr, Wolff, of Hanover'^, Pefcription of xVlY ele6lrical apparatus is a plate machine, conflruded on Uic machine. ^j^g pj^j^ ^^f ^j^^t defcribcd by Van-Matum f, with a few flight The plate. alterations, which are principally in the rubbers. The plate is eighteen inches in diameter, and the piece of wood, which receives the fcrew that faflens the plate to the axis, is an inch and half in diameter. The rubbers (at the extremities of which, toward the axis, are flicks of black fealing-wax, rounded at each end, and overhanging or projefting on three fides) are in conta61 with the glafs for the length of 5f inches, Confequently the diliance from the circular or central piece of wood to the rubbers is 2j inches, to which extent the plate ♦ From GilbeiVs Anrahn der Phy/ichy 1802, No. 13. p; 601. f Obfern;ationi fur la Phy/ique, Vol. 38, p. 437, or PhilofophicaJ Journal, 4to. Series, No. 2. % is EI^ECTRICAL-MA-Clt'lTIS^ I2j' k coated on both fides with a fufficient thicknefs of v'arnifli *. , The bow of the conduaor, which confifts of a hall fix J"ches J^'j.e^c^^^^u^or in diameter, to which is added a moveable tube with feveral fitting pieces that terminate in balls of different fizes, had at firil, at each of its extremities, as in Van-Marum's machine, a brafs cylinder three inches long and one inch thick, with an hemifphere at each end. But as condu6tors of this corii'" Aruflion are liable to difcharge themfelves, on account of thaf faiall diameter of their hemifpheres, even before they have received their full charge, I have preferred putting one Ixafs ball three inches in diameter on the upper end of the fupqrior condudor ; and another on the lower end of the inferior con- ductor. Thefe balls likewife ferve the purpofe of collecting the fluid excited at the extreme parts; for the balls, both above and below, projedl confiderably beyond the thicknefs of the plate, and prevent the efcape of the fluid as much as is poflible, particularly in a machine lefs high in proportion than that of Van-Marum. The conductor is only 4f inches diflant from the table, confequently only half the difiance of Van- Marum's ; yet the fluid does not efcape, till the conductor is overcharged. The efcape ot the fluid is prevented likewife The efcape of by an infulating fquare of glafs 42 inches, niade rough and gj^Cs piji^e pigeed eoated with copal varnifli, which is placed on the table beneath on the table be- the lower conduaor, its three fliort feet being let into the ^^'^^j."^*^*^ '^'"'' table. This fquare of glafs may be ofed on feveral occafions as an infulating fi:and. The four rubbers are made of dry walnut wood foaked in The rubbers amber varnifli, and are 5^ inches long, If broad, and a little ^ "-" ^ * more than | of an inch thick. The metallic plate that com- municates with the leather covered with amalgam, is only an If inch broad, and is fixed externally to the centre of the piece of wood. The rubbers are preflfed toward the glafs by means of a fpring. They are covered with a piece of thick woollen, upon which is a piece of fine neat's leather. After the leather is faftened to the wood, it is wetted, and prefixed between • This varnifli is compofed of copal, two ounces; gura fanda- Amber varnifli rac, one ounce j white amher, one -ounce 3 olibanum, half an ^Y,''°^'"'^ '^^ ounce J powdered and diflblved in one pound of alcohol by digef- tion in a glafs matras. When the folution is perfeilly cold, it is pafled through the filter, two ue KtECTRIC At MA^^INE. two boards, where it is kept till it is again dry. Thus it Is rendered very flat, and its edge very fliarp, and all its parts will apply to the furface of the glafs. This piece of leather is covered with another a little broader, the rough furface of which is towards the glafs, and its lower edge on the fide to- wards which the plate moves ; and its upper edge on the other fide from which the plate moves, being likewife very Iharp. The piece of filk is applied with accuracy to this leather. Before it is fattened on, it is heated, and befmeared firft with butter of cacao, then with a large quantity of Kieirt- mayer's amalgam*; and after it is fattened on, it iscompreflfed in conjun6tion with the wood, or prefled ftrongly againft the machine. The leather is next covered with amber varnilh, amalgam is fpread over this, and after the varnifli is dry, it is fmoothed with a burnittier. This is repeated feveral tinies. The whole being very dry, and the rubber being prefled fo as to touch the glafs in all points, the leather coated with amal- gam is covered with a piece of fine white paper, as long as the leather, and half an inch broader, fo as to cover the fearti that fattens the lilk to the leather, and the paper is fattened to the wood above or below, accordingly as it is on the afcend* ing or defcending fide of the plate. Dry paper is known to be capable of acquiring a high flate of eledlricity, which induced me to try this fiibttance as an immediate rubber. The following are the advantages, that by my experiments, repeated and varied in a great number of ways, I have found paper employed as a rubber to poflefs over every other known fubftance. 1. The glafs is not rendered dull by the fridlion, as happens at length, and by frequent ufing, when it is4tt ifiimediate contaft with the amalgam, does not be come 2. By the immediate cental: of the amalgam, the glafs fre- fireaky, quently contrads ftreaks here and there, that occafion a circulation of the fluid. This cannot take place in the con- ftruclion I propofe. 3. Neither the glafs nor the filk can be foiled. It is well known, that (he cleannefs of the glafs, as well as of the nefs of the whole rubber and the whole machine in general, is of importance in machine ad- Tanug^otts. « I add to this ama]g*m as much filver, as the mercury can dif» ibUe in conjunflion with the zinc. ' ' 3 producing The rubber covered with. fine white paper. What led to thisv Its advantages. The ghfs not rendered dull. and neither it nor the filk is foiled. Clean ELECTItltJAX MACHINE. 1Q!7 producing -an IntenCe degree of eledhicity. It is true, that Rubbing the it has heen propofed to apply the amalgam to the glafs in- g^^ inftead of iiead of the rubbers ; but the greater effeft, that feems to be the rubbers a bad produced by this laft method, is only apparent, and confifts "^^^ entirely in the circulation of the fluid on the glafs, while far from exciting or accumulating more of the fluid, this procefs and the circulation difperfe it. 4. The amalgam on the leather docs not require to be fre- The amalgam quently renewed. The duft of the amalgam, that is depofited f^g^g^^^j. [gJcw! on the edges of the paper, is injurious only when accumulated ing. there in fufficient quantity to be conveyed to the glafs, from which however it may eafily be removed. 5. The return and pafTage of fparks to the rubbers are The return and rendered more difficult, as the paper fufficiently covers the ^ th? rubb^e^ borders of the rubbers, that are turned toward the axis. more difficult, 6. In my conftrudion the rubbers may be larger than in the The rubbers Hfual way, and in reality they are larger in proportion in my '"^■^ ^ ongcr. machine than in Van -Mar urn's. No fpark pafTes the axis, ^P^rks do not unlefs the air be very damp ; for the fluid, in cafe of a ftrong accumulation, flies in preference to the oppofite rubber over a quarter of the periphery of the glafs. I am perfuaded, that, by adopting my conftru6tion, the rubbers of a plate of 32 inches, fuch as Van-Marura's is, may be eleven inches in- ilead of nine, in which cafe there would ftill be two inches for the diameter of the piece of wood that fattens the plate to the axis, and three inches for the difi:ance from this piece to the rubbers; which I think would be fufficient in thefe circumflances ; and the fridion being on a larger furface of the plate, the effect mufl naturally be much greater. I fliall farther triah try this alteration of the rubbers on large plates of Bohemian glafs, as well as on Englifli cylinders of 18 inches diameter, and 'J I inches long. The refult I have already obtained with afmall cylinder gives me reafon to hope much more complete fuccefs with a large one. 7. With my rubbers the fridion may be rendered much The friaion greater, than with thofe the amalgam of which is in immediate ^^y^^"^^'^^ - 1 1 /• » much greater, .i contact With the glafs, and foils it; befides, the plate turns and is uniform, with an uniform friction. 8. The aaivily of the machine is extraordinarily increafed '^^^ a^iyity of by this coiiftruaion. The greater fr^fedom with which the traoJdfnarily hiT plate creafcd, and whv. 128 CITLTIVATION OP THE SUNFLOWER* plate moves,- even under a greater prelFure, and he paper^s preventing the glafs from being foiled, would be fufficient to produce this efTedj even if the greater prelfure alone did not occaiion a more powerful effect than can be obtained from common machines. IX. On the Cultivation of the Sunjioxuer, and its Advantages *4 the fun-flower | jh£ funfiower, helianihus annuus L, is faid to have been recommended to ^- • _,, r - cukivators. brought to Lurope from I'eru. There iare two fpecies, one annual, tlie pther. perennial:, of thefe the latter is only orna- mental, but the annual is of luch ufe in agriculture, that it dei^rves to be made known to our readers. The feeds are white, gray, or blackidi ; but this difference of cOiQur is entirely accidental, as feeds of either colour pro- duce the others reciprocally. There are two varieties, how- ever, that appear to me permanent, the funflower with a fmgle ftem, and that with a branchy flem, which is lefs corarppn. The feed fliould be fovved in fpring, when nothing is to bs apprehended from the froft, that would deftroy the young plants., The ground (liould be well broken and manured, if you. would have an abundant crop. You may fow broadcaffj and afterward thin the plants: but it is better to dibble tha feed, placing two in a hole, the holes a foot dltlant, Und the rows two feet afunder. If both feeds germinate, -the weaker plant (hould be pulled up. The plants (hould be weeded, and tiie earth dug up between the rows at a proper time. The height of the plant will be from fix to nine feet: the fialks ar« large, fome of them being feven or eight inches in circum- ference near the ground. It flowers in July or Auguft, and the feeds are ripe in Autumn, at the fame time with Indian corn. Rainy feafons deftroy many of the plants : the foot of the flalk rots in the ground, the leaves fuddcnly dry up, the ilalk breaks of at the root, and the plant dies. A few funihiny days flop the progrefsof this difafter. Seeds, have tsVo va- rictfts. Method of cul- tivatio/i. Rainy feafons bad. La JPecihff Pb.ilofophique, No. 26. June, 1803, p. 607, The ^kw VEGETABLE SALT. 129 The leaves of the funflower furnifti abundance of agreeable The leaves are ^ , , . , . . r o- -iL i. excellent fodder. Tedder tor Cattle : they at-e gathered in fuccellion without any ^^rceptible injury to the plant; and after this crop of ex- cellent fodder, you may exped another of feeds that is very iibandant. Some ftalks aflTord not lefs than ten thoufand. The Mode of gather- ;beft mode of gathering them is to cut the flower ftalks, and/"^^'^ Bs the calyx is very thick, to hang them up in an airy place, that they may dry fpeedily. . When they are in flower bees flock to them frbm all quarters Be?s fond of tftft ■^ liowers. to gather honey. t The feed is rather farinaceous than oily, which they who The fefd jffbrds ■have attempted to exprefs oil from them did not confider. It Quantities. ^ is truej that oil may be exlraded from them, but in quantities 'too fmall to make it worth while to cultivate the plant for this purpofe. But if the feeds of the fubftance be incapable of aflx)rding Good food^ for 'loil with advantage, they are valuable for feeding animals * * tommonly kept in the country. They are perfedly well fuited to (heep, pigs, and other animals ; but they produce a particularly for more flriking effed on poultry. Forthefe no food is niorepro-^'JJJjJj'Jjj^Pj^" fi table, or occafions them to lay more eggss. laying. The dry flalks burn well, and afford very good aflies ^oil^^^^^^^l^^^^^^^"^ lye, becaufe they contain a great deal of alkali. In ftiort, much alkali, from the eafe with which it is cultivated, the abundance of its produce, and the change it makes in crops, the funflower may be coniidered as a new fource of wealth to the farmer. A X. Chemical Examination of a neiu Vegetable Salt, and of a neiy Acid difcovered in it : 6jf Kl a p r ox h *. JL HE vegetable production, which forms the fubje6t of the Hot climates ijrefent examination, affords a freQi proof, that hot climates ^^Jlj Jj.^^y^^Jf liave not only a great influence on the elaboration and par- cold, and create ticular modification of a great number of vegetable fub- ""'^ *'"^** flances, but that they caufe productions to be formed, the leafl: veftige of which is not to be found in the fame plants in the northern regions. I * Scherer's Allegemeines Journal derChemk) 1803, Nc. 55. p. 1. Vo]L. VII.— February, 1S04. K This 130 ^^"^ VEGETABLE SALT. A fulinc mafs f ^ig produdion confifts of a faline mafs, excluded froir/ th(? trunk of a mul- trunk of the white mulberry, inorus alba L. which was oblerv- berry tree in • ed and gathered by Mr. Thompfon, in the botanical garden ^^*^''y- at Palermo. External charac- xhe faline mafs in its native fait, as found On the furfabe of the bark, has the appearance of a coating in little gramulous drops of a yellowifti and blackifli brown. The fubflance of the bark is equally penetrated with this fait. ' ; ' '^^^^' The firft property by which it is diftinguiflied is its tafte, which comes nearefito that of the fuccinic acid. Effeft of heat. On burning coals this fait fwells up llightly, emiting a vapour fcarcely perceptible to the eye, but irritating the organ of fmeil, and leaver a flight earthy refiduum. Lixiviation > To feparate the fait, fix hundred grains of bark loaded affords a light, ^,jjj^ -^ ^^^^^ ^^ ^^ ^^^ lixiviated with a fufficient quantity pale fuK, in- ' ' -^ radiating •>eedl?s5of water. The lixivium, which was of a brownifli red colour •notdeliquefccnt. was filtered, and evaporated for cryfiallization ; when three hundred and twenty grains of a light fait were obtained, re- fecnbling in colour a pale wood, and corapofed of fiiort needles united in radii, and not attrading the moifture of the air. jjttle folublein Though thefe cryfials do not form till the lixivium is greatly looncn'iUHiza. ^^"^^"^'^'^ ^7 evaporation, the fait, neverthelefs, belongs to kie. the clafs of thofe that are little foluble ; for 1000 parts of water diffolve only 'ib parts with heat, and 15 parts cold. Contiinsno jhe folution of this fait was not rendered turbid by the jip un ci . j^^g^jj^ Qj. ^^ water of barytes, which proves, that it contains Lime precipitat- no fuiphuric acid. The alcalinule carbonates precipitate fora 1 . ^xom it, an earth of a brown wood colour, which by a flight heat is calcined to whitenefs. This earth diflblves with efl^er- vefcence in nitric acid, and was precipitated from this folu- tion in the form of fulphate of lime by means of fuiphuric acid ; and, in that of oxalate of lime by oxalic acid. Precipitates The folution of the fait readily precipitates acetite of lead, acetjre oflead, ^^^ the precipitate formed is reduced onburnino: coals. The an.i nitrate or * ' o filvcr and mer- nitrate of filver was precipitated by it in a pale brown, light, *^'y* and fliining fcales, and the nitrate of mercury in whitifli flocks. Hence it con- Thefe experiments indicate, that the fait in queflion is % tains lime, with Neutral lalt, compofed of Hme and a peculiar veeetable acid. ix peculiar ve- • • , i i • i g. til) e acid, and This acid, however, was combmed with an extradive matter, extradivc mat- which- Tendered the precipitates, that otherwife would have * , been white, either of a deep or pale wood colour. Fifty >fEW VfcGETABLfi 3ALt, "131 Fifty grains of the calcareous fait were heated to Incan-By ftrong heat clefcence, in a retort communicating with the P^^^n^^^'co-and^carbonic^" chemical mercurial apparatus^ and twelve cubic inches ofgafes,— hidrogen gas mingled with carbonic gas wer^ obtained; that burnt with a ftrong flame. The bulb of the neck of the re- tort contained ah acid liquor, on which fwam a fluid brown an acid liquor^ •1 1 ,1 - .1 • . • r • I 1^ • 'T'L anda fluid brown Oil, both together weighmg ieven or eight grains. The re-^jj^ iiduum in the retort confifted of a fpongy conglobulated mafs having a fpungy of a pale brown colour, interfperfed with coally Particles, ^^^^'J^'J™* j.^^ and difl^olved in nitric acid with effervefcence. This.folution, and a carbona- being filtered, was precipitated with carbonate of ammonia ; "°"^"**"*^* when 21 grains of carbonate of lime were feparated. The coally matter that remained on the filter was very light, weigh- ed four grains and half, and burned on a teft, leaving a re* Iiduum of a quarter of a grain of calcareous earth. Another portion of the calcareous fait was precipitated by By carbonate of Carbonate of ammonia> and the liquid remaining was eva- f^io^g flender^^ porated by a gentle heat to cryftallize it> when it furniflied a prifms wa>ob- falt in long and flender prifms. tamed. The liquor left, after the cryftals Were feparated, vvas ex- The remaining amined by feveral metallic re-agents. The folutions of filver, eiJTa'rfous'me^-' mercury, copper, iron, cobalt, and uranite in nitric acid, tallie folutiens* and ihofe of lead and iron in acetic acid, were powerfully precipitated by it. The precipitate of copper was of the colour of verdigris ; that of cobalt of a pale reddifli colour ; that of uranite of a yellowifti colour; that of iron of a dull brown ; and thofe of filver, mercury, and lead^ of a bright brown wood colour. The fame liquor was rendered flightly turbid after a time ^"'^ ^^^ ^^'' by the water and acetite of barytes, the muriate of tin and owing'toThe gold, and the nitrate of nickel ; but thefe precipitations might sxtradive mat- be the effea of the extradive matter, that adhered to the ^lYgVuy Sid! acid, rather than of a combination of this with the metallic •Oxides. I (hall proceed to the experiments I made with a view of Experiments to obtaining the acid of the calcareous fa;lt pure. °^^^^*" ^^"^ ^^''^ Forty-five grains of the precipitate obtained from the de- The precipitate compofition of the calcareous fait, by the acetite of lead, ,'^'^^^^5^'^''^^ ']^, . , •, r 1 ,i-i 1 • -ij-i J. . , * lead mixed with ware mixed with aicrupleot lulphunc aciadttuted by a drachm fuJphuricacid. of water. The fulphate of lead was feparated, and the liquor Decompofed by- evaporated. It afforded by cryftallization thirty-four grains of " ^ 9^id (alt in fine needles of the colour of pale wood. K2 la 132 NE^ VEGETACLE SALT. Decompofed by In the fame manner thirty grains of the dry calcareoits fait Su.phunc acjd. ^^^^ decompofed by twelve grains of fulphuric acid, properly diluted. The fulphate of lime being feparated, the fanve acid fait was obtained, ""i^lctl^^ The taf^e of fuccinic acid is flill more marked in the acid is oot deliqucf- itfelf. The acid fait remains dry in the air ; it is eafily foluble ctntt diffolves j^ alcohol as well as in water. It does not precipitate the readily in alcahol m- r i • i-i • r i and does notprc- metallic lOJulions like its lalt. cipitsce metaliic Twenty grains of tlie acid fait were flightly heated m a fmall In"he"etortan S^^^^ retort. Firfl, a couple of drops of an acid liquor came acid liquor came over, the tafte of which was perfectly analogous to that of the cdom-lefrTrS- -^^^^'^^^^ ^^''^' Next a concrete fait arofe, that adhered flat parent cryftala againft the top and part of the neck of the retort, in the form fublimed j and ^f prifmatic cryftals, colourlefs and tranfparent. A coally re- a coal remained. _, .,., r ^ liduum remamed m the retort. htonSy to the^^ ^ fimilar faline fublimation was not obfervable with the lime. calcareous fait : we muft therefore conclude, that the acid ad- heres flrongly to the lime, and cannot be feparated from it by heat, without being decompofed. The acid wafhed Xo feparate the fublimed fait from the coally refiduum, the tallized. ^^ ' whole contents of the retort were difiblved, and the liquor filtered. The folution was perfedly clear, and by fpontaneous evaporation depofited the acid fait in colowlefs cryftals, Sublimarfon the fj^Q^ this it appears, that a gentle fublimation is the befl beil mode of ob- , r . • • , •, ri tr • ■ r i taifiing it pure, mode or obtainmg the pure acid lalt, and treeing it Irom the extradlive matter, to which it adheres too flrongly to be fe* parated from ii in the moift way. Perhaps may be The fmall quantity of the calcareous fait I had left, did not ^ u?b"r tree 2il^o ^ ^^ ^^ carry the examination as far as I could have wiflied, in this climate, in order to -determine the fpecific characters of the acid. It is poffible, that the mulberry trees in this climate may likewife furnifli the fame lalt, and I (hall proceed to inquire into this without delay. A new acid, the ' 'pj^^j experiments related, however, feem fufficiently to the fdit moroxy- ellablifli the point of the acid obtained, being a new vegetable kte of lime, ^^id, which comes ncareft to the fuccinic, both in its tafte and otlier qualities. We may therefore provifionally give it the name of moroxylic acid, and the calcareous fait containing it that of moroxylate of ii)ne. XL On ?;yOOLF's ROTATORY APPARATUS. 133 XL On Mr. Woolf's Invention for equalizing the ASlion of a Crank, in contradijiinaionto the Efftd of the Fly, in pro- ducing an uniform Efedt againji a variable Rejijiance. In a l^etter from Mr, T. Jones. To Mr. NICHOLSON, SIR, 1 BEG leave to fecond Mr. Fafcy's requefl: for an expla- J"^"j'y !1^P^S;' nation of the fubftitute f<^r the fly and equalization of the fubftitute for a adion of the fteam engine, in producing a rotative motion, fly. given in your valuable work for November laft : or, I (hall efteem it a favour if you can dire<5l me where I can fee it at work *. It appears to me, that the inventor has loft fight of the value of that organ which he intends to fuperfede, and that he has not applied it in cafes, where a machine is required to produce an uniform efl^e6l on a variable refiftance, in which cafe the mere equalifation of the a6lion of the power on a revolving crank would have no value at all. The beft attempt that I h^ve feen to unite thefe two im- Another attempt portant points, is in a fteam engine ereded by Mr. Horn- gfje^^ blower, at MeflTrs. Meux and Go's, brewery, where the a6lion of the power on the pin of the crank, may have been in the ratio of the fines of each refpedlive arc in its revo- lution round the arbor of the fly, I fay, " may have been" and I wonder '\t was not, (ince that mode of communication would have fo eafily admitted it,-— theoretically at leafl: ; |hen indeed, a very light fly would ferve to turn the crank paft the upper and nether part or points of the circle ; but it could not have anfwered in regulating the unequal refif- tance which is found even in grinding malt^i or pump works ; and in my humble judgment, the fly muft for ever keep its place and importance with evepy judicious mechanic, I am, in rnuch bodily indifpofition, S I R, Your humble fervant, T. JONES, Surry Roadj 1th Januari^ 1804. * If there be one at work near London, I have no doubt but Mr. Woolf the inventor, who is refident engineer at Meflrs. Meuj^'s brewery, will readily (liew it, N, Farther 134 woolf's rotatory apparatus. farther Remarks on Mr, Woolf's Rotatoria Apparatus, ^* w^ir"*^"""' ^ ^ ^^^^^" ^^ ^^^^^'^ the efTed of Mr. WoolPs contrivancq tory apparatus/ {-^f^'- 1* ^^^^^ XI. Vol. VI. November .1^03.) more intelli- gilple to my readers in general, I ihall here explain the fame in a popular way. I will fuppofe, by way of fimplifying the fubjecl, that the rod B is fo long as to act always nearly in the perpendicular, and that the adion upon the fmall wheel is alfo in ithe fame diredion, namely, conftantly that of gravity. The en- graver has omitted to continue the rod of the pifton fup- pofed to Work in the barrel G, and the proof canie too late for it to be altered in time. The effedl at the pin F in the little wheel, is precifely the fame as if a weight was conti- nually hanging there. Effeftofthe 1. In the pofition here (liewn, the power of the engine ^^\oh Tn diffc- ^^^^ "^^ ^^ ^^ ^^^* ^"*^ ^^^^ weight at F has its full operation. ^eqt pofitions. —2. When C has moved through half the quarter circle to the right hand, F will have arrived at the loweft point; confequently the poWer of the engine will aft by a lever eiqukl to the line of 45^, or feven-tenths of the radms: oi* feven-tenths of the full power of the engine will then a6l bn the great wheel, and the weight at F will no't a6l at all : —3. When C has moved through an entire quadrant, the power of the engine will be the greatefl poflible on the J^reat wheel, but at the fame time the weight will have arrived at the horizontal line beneath E, and will oppofe the former action. The motive force will therefore be equal to the excefs of the power of the engine beyorid the weight. 4. When C has> moved through another half quadrant^ the action oh the great wheel will be equal to feveh«tenths, as i\\ No. 2. and the weight, having arrived at the highefl ^ point will not ad at all. 5. When C has moved through half a circle, and is at the lower flation in the great wheel the engine will not ad, and the weight having arrived again at F. will have its full operation as in No. 1. four ' ^y P"^"^"^^g *^^^ fimple method of examination, we fee positions n .that 1. there are four pofitions in which the arm C tlanding which the coun- ^j. ^^ inclination of 45° to the horizon, and the arm F per- aocffe'l/ " p^jidicular to thefamelthe regulating weight cau' have no effe^, WOOI.F"'S'ROTATOKT apparatus; 135 effeS, whatever be its njeafure ; the ad^ion will be ef- i'ddual to fcven-tenths of" the direct or entire ad ion of tiie arm. B in the tangent to the great circle ; 2. that when the two in whtd>th* arm C is either perpendicularly u

veit. f ft ON EXTINCT VOLCAN©!^. } 37 To my great fatisfa^lion, after having traverfed pumice A quarry of (tones and volcanic fcoria?, I arrived at the foot of a quarry j^^^y^ "JJ^^^ j[^^ of lava, fr®m which hewn flones for building and millftones miliftoncs were were taken. This quarry was wrought in the open air, ^^^, Wroueht in th- was covered with a bed of mould about eighteen feet deep, open air, and Thethicknefs of this ftratum demonflrates the high anti- "^^'^'^ ^^^^ ^ r , , ., r ' ■ . ^'g"teen feet of quity or the volcano, while at the fame time it prevented mould. me from tracing the courfe of the lava, particularly as above Above it fcatter- this lava, nothing is to be found but fcattered blocks and fragments ^of fragments of lava, fcoriae, and pumice flones. I went to lava, fcoria, and the top of the mountain, however, in hopes of difcovering P""^'^^ **o"e. where the center might have been ; for the mountain of Agemberg not Agemberg, all the rocks of which are torrefied, and the * ^"J^*"' ftate of fcoriie, was not a crater. The rnountains, by tains furround- which it is furrounded on the weft, appeared tc me to be of'"g 'tj of the the fame nature, without any indication of the mouth from ♦^""^"^^"^^» which the fire ifiiied. The fummit of mount Agemberg Is very bare, but on The top of defcending a few paces, I foqnd a very pleafant copfe. A ^^]^,^'ie^Jf ^^^^* narrow path, which I took at a venture, led me, after fome down a pleafant twenty fieps, to a grotto, in which was a tomb, with an f°P^"» *" ^'^"-"^ ' r •\- r T? • 1- PT- ,• /- IS a grotto, con- iBlcription trom Job, reminding man oi his nothingnels. taining a tomb. By the fide of this grotto is another, inhabited by a hermit, ^"other inhabit- with a table of volcanic ftone in the centre, which he ufes a third in \di'icl> for different purpofes. A little higher up, I difcoveied a 's a" altar, a pi- third, fmaller than either of thefe, containing a rufiic altar ; fwo^ol" three '"'* pn one fide was a pigeon-houfe, and lower down, two or bafons of water, three IJttle bafons of water bordered with fliells. I quitted this mountain with regret, to traverfe another. Another moun- which, though covered with wood, feemed to indicate the t'ees'^anrdtet''' pxifi:ence of a crater; but I could perceive no trace of™''"!^* one, the trees, and the thicknefs of the mould, letting me bloc^J'onYv^^^ fee nothing but fcattered blocks of lava and fcoriiB. and fcoria. My examination was foon finiflied, and I refumed the ^" ^^e road to road to the abbey of Haach. In this I found nothing but Saach^'pumice pumice fipnes, lava; in fome places of the bafaltic kind, ftones, lava, i^ fcoris, a few fragments of hornfione fchifius, and blocks IJfSc,*'l^"is,^* of quartz ; all fcattered about on a firatum of earthy which homftone, fchif, itfelf was compofed merely of river-livnd and pumice *J'/''JJ'^^ ''^°''^* A^ne. on a ftratum of The '"''^^'' ^and and pumice ftcae. J38 ON EXTINCT VOLCANOES. The crater fald The incumbent of the village belonging to the abbey, fn*' its fiuiation * ^'^''^i^ed me, that the crater, of which I was in fearch, was- iiijc. a lake near his parifh. fefttgiUf dif! ^^^^^ fituation of this lake difplays much grandeur. It is terem colours, furrouuded by a chain of mountains covered with trees ; t^xt fwtte^er' ^^^ ^*^^ ^^ '^^'^'' longed from north to fouth ; and it requires blocks of lava, near two hours to walk round it. TKe^ank a popr The weft fide offeri? to view at firft nothing but a fpacious On the north, ''^ed of argil, divided into bands of diftbrents colours ; after block, of lava, this appears a fmaller bed of hornftone ; and the reft exhibits cleic p^rpendi- ^"^7 ^'^"^^ fcattered blocks of lava. The bank is an indif- cui^iy, fcrent meadow. Shltetiay,* a*^^ The north fide bpgins with fome of the blocks of lava juft teifperfedwlth mentioned: next appears a pretty extenftve bed of horn- '^'"d^f^ ^\^^^ ftone, the very numerous fifiures of which are uniformly Onthe^art, perpendicular to the hoiizon: and a little farther on, is a compad and coniiderabic bed of fat clay, as white as fnow, interfperfed pr>rous lava, aad .,,,,, rx ii n ibcnwuhtim ^'*^" blocks or lava and Iprnuone. nearly perpetidi- Qn approaching tlie eaft Ihore, iiothing is to be found On*the fouth a ^"^ ^^^'^' "' i'ome places compact, in others poious, and the level meadow, mountain there is nearly perpendicular. vCTed wltT "^^^ l-aftly, on the fouth fide, the ground becomes level, and fliePs. is firaply a meadow. The ftrand is covered with fhclls, Ti»e prev3t)mg partly whoJe, partly broken; and hence I conclude, that winds N. and ^ -^ ... ^ ./.,..'. ^ N. VV\ the prevailing winds in this autiict, are the north and north- The lake has no weft. . - apparent influx -pj^jj, |^j^^ ^j^^g ^^^ appear to me to receive water in anv of water, but a ri /- m fivulet runs part : yet, on the fouth it has an outlet, that furnilhes a fmall ^ofTiitanthe t^rook, watering the groijnds of Medermich. The depth V i' reatWin ^^ ^^^ ^^^*^ varies greatly, being upwards of four hundred depth, m )re feet near the middle, It abounds with fiih, particularly than 400 feet jj^^ ^^^ ^1^^ blocks of ftone fcattered over its bottom, near the middle, f^ ' - r , ^ ■ -^- 1 1 r 1 1 Abounds with render the uie or the net nearly impracticable, lo that the £{k, but the bot- |j,^p j^ almoft exclulively onployed for catching them, ufe^nets!"^ ^ The abbey, to which this lake belonged, was a fpacious The abbey bai't building, proclaipiing the opulence of its founder. It was bythe count Fa- b^iiij. [^ ]093, by Henry count of the Palatinate of the- he'b"*in" ila^m- i^hine, and lord of this lake. Broverus, in his annals of ei by the noe- Treves, fays, that the phantoms and lights, which this prince torna. 9j>pe3\- ^ every night on the mountainy around him, induced hir^, ance or fires on j o the mouncjuns. to ^ EXTINCr v6lCA^6E*§^ Once a volcano* I had no doubt, that this mountain was once a vofcano, if < figure alone proves it. I went beyond it to the quarries that were working, and which were to the north, at the foot of a' Near it quarries gentle declivity, feparated from the Calberg by a valley, ^f !h^'* • through which a fmall brook flowed to the eaft. Thefe quari fpeciesj ^ies are parts of vaft beds of that kind of lava, which the Ita- lians call piperino. It is in general an earthy lava, contain- ing a pretty confi'derable quantity of fragments of compa6l: wrou'^h'!"^^^ lava. This ftone is foft, and eafily wrought. It is almoft in fomc places every where in a horizontal flratum, but varies in its texture^ a volcanic brec- f^^ j,^ ^^^^q places it appears in the form of a volcanic breccia, ciaj in others . '^ \' r r j n ef afandftone m Others it has the texture ot land-ltone. texture. Having accompiiftied my objed, which was to difcoverthe dermcnTch to ^* volcanic openings, that furnilhed the lava of this diftridl^ I Coblentz. returned to the Medermenich, where I flept; and the neit The plain dU day I reached Coblentz. The plain I crolfed was covered vercd with frag- ^,jjj^ fragments of quartz, trapp, and pumice {lone. Near ttapp, and ' 06lundung, on the high road, we find rocks of flate, which pumice ftone, ^^q working. After leaving this village four gently floping innl flate'^quar- mountains appear on the left^ ftretching from eaft to weft, Ti6s, and feparated dniy by narrovv valleys, Theif figure induced ranicmoun-'"'^''"^ to vifit them'; and I found th^m compofed of pumice tdnS, ftones and fcoride. The firft and fecond are merely fegments «f two fmall craters, the northern part of which has been car- ried away. The other two, which are covered with trees^ appear to me to have formed but one crater of vaft extent^ Their lava en- the fouthern part of which is deftroyed. The lava of thef6 cfufted with \iit\e mountains is encrufted with an immenfe number of little p^oxen? *^° cryftals of piroxen. This reddifli lava contains a pretty con- It is reddiOi, fiderable quantity of reddifti mica in large leaves, frequently and contains red- j^^j^ ^ ^^^ ^^-^^^ Almoft at the foot of the eaftemmoft moun- fliin mica in large leaves. tain this ftone is procured, to be ufed in conftrudting walls^ Uled in walls, though it is too porous, and at the fame time too hard, to be employed as hewn ftone. View from thefe ^^om the fumrait of thefe heights the profpe6t is beautiful heights. and grand. From the eaft to the north appears the magnificent bafin watered by the Rhine from the caftle of Ehrenbreitftein to Andernach. The (even mountains (Siebenberge) raife their ancient heads on the north. On the weft, the view in- cludes from north to foath all the mountains juft defcribed; and ON SPECTACLE GLASSE!?. 243 and on the fouth it is terminated by mountains covered with wood, the neareft of which appeared to me to be volcanic. At length I arrived at Bafnheim, remarkable for nothing but ^^^if^^^-^^ the EngliQi gardens belonging to the lord of the manor; and Fuojice ftoncoo thence to Coblentz. I found pumice Hone on the road, and ^^ ro-Jdandia m itrata where pits had been dug in the ground. XIII. On an hnprovement in the Form of SpeStacle-GlaJfes, i»yWiLLi am ' . HYDb Won. A ST ON, M D. F. R. S. Communicated by tht .Tmufl h^ve been remarked by perfons wbo make "^^ of J"^Frfcaion of fpedlacles, efpecially thofe who require glaflTes of thort focal objeas out of diftance, that obje6ls feen through them appear diftin6l, only <^enter are diT- ^ when viewed through the central parts of the glalTes ; that when the dire6lion of the fight E O, Fig. 1 . page 14-5 is con- fiderably inclined to the furfaces, objects appear diftorted, and that this dcfe<5l is greater in proportion to the greater obliquity of that line. ' It is on this account that opticians have lately made, and j^cwedy fonncr^ recommended fpe^Sicle-glafles of lefs diameter than thofe make die glaffes formerly in ufe, thinking that the extreme parts of the field Smaller j— of vifion, which from indiftin<5inefs were of little ufe, might be fpared without much inconvenience. But this alteration but to iJttIc in the lize of the glafles could hardly claim the merit of an ^^^^» improvement; fi nee for one defeat, it only fubftituted another fcarcely lefs objed^ionable. It feems indeed rather extraordinary, that, during five centuries which haveelapfed fince the invention of fpedlacles, neither theory nor accident fhould have produced any con- tiderable variation from the original conflrudion. ' It was indeed conceived by Huygens, that the glafies, in- Huyghens pro- (lead of being equally curved on both fides, as is cufiomary, P"J5.^ that the ^ (hould have the curvatures of their oppofite furfaces in the ture In fpefta- proportion of fix to one, b6cauf Fig. 3. To Fir / It is only neceflary to add, that the advantage of this im- E*P«"cncc coa*.. provement in the form of fpedacle glaffes has been confirmed f^l^e!'^"' **°*'" by a fufficient number of experiments on different perfons, and that thofe in particular who are very long or very fliort lighted, are much benefited by them. * To mathematicians it will be evident that any ray which does not pafs through the center of a lens, cannot be at right angles to both furfaces } but they will alfo perceive that when any fmall ob- lique pencil makes equal angles with the two furfaces of a thin lens, the inclination ©f it to each is fo fmall, that its focal length B D, Fig. 4. will not fenfibly differ from A C that of a central pencil. Vol.VII.—February, 1804.. L The 145 •nd a manufac- tory is eftablifh- cd. The fpeftades are called perif- copic. GUN TO THROW DOUBLE-HEADED StfOf. Tlie moft advantageous proportions of curvature for obtain- ing the different focal lengths now generally diftinguiihed by certain numbers, have alfo been duly confidered; and the nianufaflure of fpeflacles, on this conftru6tion, has been un- dertaken by Meflrs. P. and J. Dollond, to whom the exclufive fale of them is fecured by patent, and whofe well known ikill in the conftru6lion of optical inftruments, enfures to this im- provement every advantage of corre6l execution. From the opportunity afforded by thefe glafies of looking round at various objects in one pofition of the head, it is thought they may not improperly be diftinguiflied by the name of Perifcopic Spectacles. XIV. Letter of Enquiry concerning a Gun to throw double-headed Shot; ivith the Editor^s Reply i SIR, To Mr. NICHOLSON. de- Jnl, at the Royal lililitutioii. Drawing andde- iJlAVING this inftant feen, at the Royal Inftitution, a (lieet g'an'on'a paper of paper printed by Nicliols, printer. Earls Court, Newport Street, Soho, containing a drawing and defcription of a gun to throw double-headed fliot, I take the liberty of writing this on a page of a little note-book there, which niuft be my apology for the paper, to entreat that you will obferve upon it in your in- valuable Journal, becaufe I fear that it is not a fafe inltru- ment. A confiderable diftance is to be obferved between the powder fired and the fliot to be difcharged by it. I have al- ways confidered that an interval fo kept was the occalion of the burfiing of fo many guns. Pray is this fafe? And fiiould not a line be cut on the arms to which the bullets are attached, to mark txadly the diftance of the attaching bar at each extre- mity from the muzzle, when the balls are equally rammed down. As the knowledge of its fafety may contribute to its fervice if really ufeful, I hope you will think this application not idle. I am. Sir, Your con flant R e a d e r . ANSWER ANSWER. W. N. THE paper alluded to in the letter of my correfpondent. More particular Contains an engra^fing of the ftiaded fedlion of a gun having a account* double borcj but only one chamber ; from which each bore dire6tly leads i but they diverge from each other in an angle of about eighteen degrees. The charge of povvder is to be placed in the chamber^ and the two (hot, one for each bore, are conneded by a bar having two joints or hinges at an equal diftance from its middle. By this contrivance, by bending the compoifnd piece at the hinges, the (hot can be put into the bores of the gun; and when the explofion blows them out^ their divergence caufes the bar to become (Irait, and confe- quently is expe^ed to do mifchief proportioned to the extent of its length. The title of the paper is, " Horizontal Seflion of a Gun for Title of tliei projeaing double-headed Shdt, invented by Lieut. Colonel P^P-^.^J^'*^^'^* Blaquiere, 22 Dragoons, July, 1803. Recommended to be ufed againft an invading Army on board his Majefty's Gun- Boats ;*' and in the diredlions care is prefcribed, that the fame length of bar ftiall be left out of each muzzle to prevent acci- dent 5 and it is dated to be a great advantage, that a confider- able diftance (liould be left between the powder and (liot, as; hy this means the powder acquires itsgreateft potfible force. My opinion was atked concerning a gun of this defcription This gun iri- which another inventor had pnopofed, fome time previous to'^^^^f^ ^^^^ ^y _,. ,- - ^ , , r ' I , fi- . another perfori. Midlummer la(t, to throw cham-lhot ; and the oblervations that then occurred were, 1. If there be the leaft difference its probable between the windages or the blaft in each bore, or in the cafual^'^^^*^ impediments, one (hot will precede the other* 2; If they go out fairly together, their velocity of feparation will be to the direct' velocity as the chord of the angle of divergence is to the radius. In the prefent gun the balls will feparate w'ith one- third of the velocity with v^rhich they advance. 3. That the violent feparation of the (hot from each other, will moft pro- bably, in either of thefe cafes, break the chain, or the bar, or the joints. 4. Or if no fradlure takes place, the fudden check ivill, by the elafticity of the metal, caufe the (hot to approach again to each other. 5. To which I may add> that it may be doubted whether the embarra(rment of one of thefe bar-fliots ^ preceding the other might not occation a dangerous obfiruc- L2 .(ion. 1^^ t'ROGNOSTiCS OF tHE WEATliEKi tlon, and that there are many fa6ls which fhevr, that it is unfafd to permit any conliderable expanfion oF, or fpace for, the blaft of powder, before it fliall act on the proje6lile. Jntrodaftion. Pr )gnoftics of the weather. XV. Prognopcs of the Weather, efiahlijhed hy long-Continued Obfer-^ vation upon the Condudl and Appearances of Birds, Beajls, JnfdSis, Plants, Meteors, the Heavenly Bodies, Minerals, d^c. Cmnmunicated by a Correfpondent. SIR, To Mr. NICHOLSON, It is a well known general fad, that (hephcrds and othere;, whofe occupations lie in the open air, do not unfrequently poflefs the fkill of foretelling the weather for conliderable pe~ riods of time in advance, and that they ground their obferva- tions upon the phenomena exhibited by animals, and other bodies expofed to the a6lion of the elements. Some of the maxims on this fubjedl, which poflefs the fan6lion of ancient acquiefcence, are fuch as probably would not fland the teft W modern fcientific examination ; but on the other hand, there are many of which the rationale appears not difficult to explain, and others which, from their empyrical value, are highly de- ferving to be fludied and made out. I have for thefe reafons, as well as from a fenfe of the immediate utility of this know- ledge, thought it by no means impertinent to beg that you would oblige the world with the enclofed, which is the bed colledion of fa6ls I have met with. It is taken from a fmall pamphlet printed at Edinburgh, without date or the name of bookfeller or author, but apparently many years ago, intitled, A Succinct Treatife of Popular Aftronomy. If this commu- nication (bould meet the honour of infertion in your excellent , Mifcellany, I hope it will be followed by fome explanations from your fcientific correfpondents. I am. Sir, Your obliged reader, R. B. ' Signs PROGNOSTICS OP THE WEATHER. J 49 Sigm of Bain from Birds. SEA and frefli water-fowls, fijch as cormorants, fea-gulls, Prognoftics of muir-hens, &c. flying from fea, or the frefli waters, to land, Rai,7frorn birds fiiew bad weather at hand : land fowls flying to waters, and thofe (baking, wafliing, and noify, efpecially in the evening, denote the fame: geefe, ducks, coots, &c. picking, fliaking, wafhing, and noify j rooks and crows in flocks, and fud^enly difappearing ; pyes and jays in flocks, and very noify ; the raven or hooded-crow crying in the morning, with an inter- ruption In their notes, or crows being very clamorous at even ; the heron, bittern and fwallow flying low ; birds, forfaking their meat and flying to their nefls ; poulfry going to rooft, or pid- geons to their dove-houfe ; tame fowls grubbing in the duft, and clapping their wings ; fmall birds feeniing to duck, and wafti in the (and ; thef late and early crowing of the cock, and clapping his wings ; the early finging of vvood-Iarks ; the early chirping of fparrows ; the early note of the chaffinch near houfes ; the dull appearance of robin red-breaft near houfes ; peacocks and owls urtufually clamorous. Signs of Wind from Birds, Sea and frefli water- fowls gathering in flocks to the banks^ Wind from and there fporting, efpecially in the morning ; wild geefe flying high, and in flocks, and dire^ing their courfe eaftward; coots refllefs and clamorous ; the hoopoe loud in his note ; the kingVfiflier taking lo land; rooks darting or fliooting in the air, or fporting on the banks of frefli waters ; and laflly, the appearance of the malefigie at fea is a certain forerunner of violent winds, and (early in the niorning) denotes horrible tempefts ?it band. Signs of Fair Weather from Birds. Halcyons, fea-ducks, &c. leaving the land and flocking to Fair weather the fea; kites, herons, bitterns and fwallows flying high and from birds, loud in their notes; lapwings refl;lefs and clamorous; fparrows after fun-rife reftlefs and noify ; ravens, hawks and keftrils (in the morning) loud in their notes ; robin red-breaft mounted high, and loud in his fong ; larks foaring high, and loud in their fongs ; owls hooting with an eafy and cle^ note ; bats ap-r pearing early in the evening. Signs 150 FROGNOSTICS OF THE WEATHER^ K Signs of Rain from Beajla. Ramfroiri Afles braying more frequently than ufual; hogs playing^ ^ ' fcaltering their food, or carrying ftraw in their mouths ; oxeq fnuffijig theiair, looking to the fouth, while lying on their right fides, or licking their hooves; cattle grafping for air at noon; calves running violently and gamboling; deer, flieep, or goats, leaping, fighting or pufliing; c^ts wafhing their face and ears ; dogs eagerly fcraping up earth ; foxes barking, or wolves howl- ing; moles throwing up earth more than ufual ; rats and mice more reftlefs than ufual ; a grumbling noife in the belly of hounds. Sigm qf Rain from lnftQ.s. Jl^ain from in- Worms crawling outof the earth in great abundance; fpidets lefts* falling from their webs ; flies dull and reftlefs ; ants haflening to their neils ; bees haftening liome, and keeping clofe in their hives ; frogs and toads drawing nigh to hpufes; frogs croaking from ditches; toads crying on eminences; gnats finging more than ufpal; but, if gnats play in the open aifj, /^N^ ■ or if hornets, wafps, and glow-worms appear plentifully in "^ the evening, or if fpiders webs are feen in the air, or on the grafs, or trees^ thefe do a]l denote faiir and warm weather ^han.d. - Signs of Rain from the Sun. ILain, from fun. Sun rifing dim or watcrilb ; rifing red with blackifli beams mixed along with his rays; riling in a mufly or muddy colour; fifing red and turning blackilh ; fettirg under a thick cloud ; fetting with a red iky in the eaft. N. B. Sudden rains never laft long; but when the air grows thick by degrees, and the fun, moon, and ftars thine dimmer apd diinmer, then it is like to rain fix hours ufually. Signs of Wind from the Sun, Wind from the ^"" rifing pale and fetting red, with an iris; rifing large in iun. furface ; rifing with a red fky in the north ; felting of a bloody colour ; fettirg pale, with one or more dark circles, or ac- companied with red flreaks ; feeming concave or hollow | feeming divided, great ftorms ; parhelia, or meek funs, never appear, but are followed by tempefts. PROGNOSTICS UF THE WJ^ATHER. ]51 Signs of Fair Weather from the Sun. Sun rifing clear, having fet clear the night before ; rifing Fair weatb«? while the clouds about him are driving to the well; rifxng ^''"'"^ * "'*' with an iris around him, and that iris wearing away equally on all fides> then expefl fair and fettled weather; rifing clear and not hot ; fetting in red clouds, according to the old obr fervation; The evtning red and morning grey, Js the fare Jign of a fair day. I Signs of Rain from thq Moon* Moon pale in colour, rain; horns blunt at firfl rifing, rain; Rain, from thp horns blunt, at or within two or three days after change, de- ^°'^^' .^fiotes rain for that quarter; an iris with a fouth wind, rain ^ext day; wind fouih third night after change, rain next day; I fthe wind fouth, and the moon not feen before the fourth night, ;Tain raoft of that month ; full moon in April, new and full ilttoon in Auguft, for moft part, bring rain; mock-moons are .^he forerunners of great rains, land-floods^ and inundatiion. Sigjis of Wind from the Moon, Moon feeming greatly enlarged; appearing of a red co- w^nd from the lour; horns ftiarp and blackilb ; if included with a clear and '"'*°"* ruddy iris; if the iris be double, or feem to be broken in parts, tempefts. N.B. Ori the new moon, the wind for the moft part changes. When the moon, at four days old, has her horns fliarp, (he foretels a tempeft at fea, unlefs (he has a circle about her, and that too entire, becaufe, by that (he fhews that it is pot like to be bad weather, till it is full moop. Signs of Fair Weather from the Moon, Moon feeming to exhibit bright fpots; a clear iris with full f^^"* weather ^ r .1 r - ,-11 r u 1 1 . /- ^ "oni the moon, moon; horns fliarp fourth day, fair till full; horns blunt at fir ft rifing, or within two or "three days after change, denotes rain for that fjLiarter ; but fair weather the other three quarters ; moon clear three days after change or before full, always de- notes fair weather. After every change and full, rains for the mod part, fucceeded by fair fettled weather j moon clear and bright, always fair weather. Si^ns 152 PROGNOSTICS OF THE WEATHER. Weather from ftars. Rain from clouds* Wind from clouds. II ^In from jaiobow. Signs of Weather from the Stars, Stars feeming large, dull, and pale of colour, rain ; or when their twinkling is not perceptible, or if encompanfed with an iris. In fummer, when wind is at eaft, and ftars feem greater than ufual, then expc61 fudden rain; ftars ap- pearing great in number, yet clear and bright, feeming to ftioot or dart, denote fair weather in fummer, and in winter . froft. Signs of Rain from the Clouds. In cloudy weather, when the wind falls, rain follows ; clouds growing bigger, or feeming like rocks or towers fet- ling on mountains tops ; coming from the fouth, or often changing their courfe ; many in number at north weft in the even; being black in colour from the eaft, rain at night; but out of the weft, rain next day ; being many like fleeces of wool, from the eaft, rain for two or three days; lying like ridges about mid-day in the fouth-weft, ftiews great ftorms both of wind and rain to be nigh. Signs of Wind from the Clouds. Clouds flying to and fro; appearing fuddenly from the fouth or weft ; appearing red, or accompanied with rednefs in the air, efpecially in the morning; being of a leadifli colour in the north-weft ; (ingle clouds denote wind from whence they come; but if at fun-fet, clouds appear with golden edges, or diminifli in bulk, or fmall clouds fink low, or draw againft the wind, or appear fmall, white, and fcattered in the north-weft (fuch as are vulgarly called mackerel) when fhe fun is high, Ihefe are figns of fair weather. N. B It is often obferved, that though the mackerel flcy denotes fair weather for that day, yet for the moft part, rain follows in a day or two after. Signs of Bain from the Rainbow. After a long drought, the rainbow denotes fudden and heavy rains; if green be the predominant colour, it denotes rain, but if red, wind with rain; if the clouds grow darker;, rain; if the bow feems broken, violent ftorms ; if appearing at noon, much rain; if in the weft, great rain, with thunder. N.B. PROGNOSTICS OF THE WEATHER, 153 N, B. It is obferved, that if the laft week in February, and the firft fortnight of March, be moftly rainy, and attended with frequent appearances of the bow, a wet fpring and fum- mer may be expedled. Signs of Fair Weather from the' Rainbow. The rainbow appearing after long rains, denotes fair Fair from raio- weather at hand ; if the colours grow lighter, fair ; if the bow ®^* fuddenly difappears, fair ; if the bow appear in th' morning, it is the fign of fmall rains, followed by fair weather ; if ap- pearing at night, fair weather ; if appearing in the eaft, in the evening, fair; if the bow appear double, it denotes fair weather at prefent, but rain in a few days ; if in autumn, it continues fair for two days after the appearance of the aurora borealis. expedl fair weather for at leaft eight days more. Signs of Rain from Mifis. If mifts be attracted to the tops of hills then expe6l rain in Rain from a day or two; if in dry weather, they be obferved to afcend"^'^'' more than ufual then expedl fudden rain; mifts in the new moon always foreftiew rain in the old; mifts alfo in the old moon denote rains to happen in the new ; a mifty white fcare, in a clear Iky, in the fouth-eaft is always a forerunner of rain. Signs of Fair Weather from Mifis, If mifts diffipate quickly, or defcend after rain, it is a fure Fair from ralfts« fign of fair weather; a general mift before fun riiing near the full moon, denotes fair weather for about a fortnight running. If after fun fet or before fun rife, a while mift arife from the waters and meads, it denotes warm and fair weather next day. A mifty dewonthe infide of glafs windows (hews fair weather for that day. Signs of Rain from inanimate Bodies. ^ Wood fwelling, or ftones feeming to fweat; lute or viol Rain from in- ft rings breaking; printed canvas or pafted maps relaxing ; fait ^""^'« ho^^ts, becoming moift; rivers finking, or floods fuddenly abating; remarkable fpaikling of lamps or candles; remarkable halo about the candle; great idrynefs of the earth; pools feeming troubled or muddy; yellow fcum on the furface of ftagnant waters; dandelion or pimpernel fliuttlng up; trefoil fwelling in ftalk, while the leaves bow down. N, B. A dry fpring is always attended with a rainy winter. Signs 154* PROGNOSTICS OF THE WEATHER, Sigrii of Wind from inanimate Bodies. J^imate bTJeT Winds fhifting to the oppofite point; fea calm, with amur. muring noife; a murmuring noife from the woods and rocks; when the air is calm; leaves and feathers feeniing much agi- tated; tides high when the thermometer is high; trembling or flexuous burning of flames; coal burning white with a mur- muring noife; thunder in the morning with a clear Iky ; thun- der from the north. N, B. Whenfoever the wind begins to ftiift, it will not reft till it comes to the oppofite point; and, if the wind be in the north, it will be cold; if in the norlh-eaft colder; if in the fputh ; ^t brings rain ; but if in the foulh-weft more rain. Signs of Rain ceafn}g. R^lnceafipg, The fudden clofing of gaps in the earth; the remarkable rifing of fprings or rivers ; if the rain begins an hour or two before fun rife it is like to be fair ere noon ; but if an hour or two after fun-rife, it for the moft part, happens to continue all day and then to ceafe; when it begins to rain from the fouth with a high wind for two or three hours, and that the wind falls, and it ftill continues raining, it is then like to continue for twelve hours or more, and then to ceafe. N. B. Thefe long rains feldom happen to hold above twenty- four hours, or b^pperx above once a year. Signs of Wind ceafng. Wind ccafing, -A hafty (bower after raging winds is a fure lign of the ftorra being near an end. If the water ruckles and frequent bubbles arife, or if the halcyon or kings-fifljer attempts the fea while the ftorraJafts, or moles come out of their hples, or fparrows chirp merrily, thefe are all certain figns of the ftorm ceafing Both fea and frefti water fi flies by their frequent rifing and flut- tering on the furface of the water, foretell iheftorm nigh over, but efpecially dolphins fpouting up water in a ftorm Ibretell a, calm. N. B. Let the wind be in what quarter it vvill upon the neyf moon, it prefently changes. Sigm of Hail, Kail. Clouds while. Inclining to yellow, and moving heavily though the wind be high is a fure fjgn of hail; if the eaftern- Iky before fun* rife be pale, and relracU'd rays appear in thick - clouds^ ^ROfrNOSpripS OF T|tB WEATHER. J5j5 cloucjs, then expeft great ^orms of hail; white clouds infum* mer are a fign of hail, but in winter they denote fnow, efpe- cially when we perceive the air to be a httle warm; in fpring .or winter when clouds appear of 4 blueifti white^ and expand much, expert fmall hail or drizjsling, which properly is no other tlian frozen mifts. Signs of Thunder. ^ , ^ . . Meteors fhooting in the fummer's evening, or chops and clefts Thunder^ In the earth, when the weather is fultry, always foretell thun- der is nigh; in fummer or harveft, when the wind has been fouth two or three days, and the thermometer high, and clouds rife with great white tops like towers, as if one were upon the top of another and joined with black on the nether lide, expe(^ rain and thunder fuddenly ; if two fuch clouds arife, one on either hand, it is then time to look for fhelter, as the thunder is very nigh« N.B. It is obferved that it thunders moft with a fouth wind ;and leafl with an eail. Signs of Cold and Frojiy Weather. Sea-pyes, ftarlings, fieldfares, with other migratory birds Cold and fr«fty« appearing early, denote ^ cold feafon to enfue; the early ap- pearance of fmall birds in flocks and of robin redjrbreafts near houfes; fun in harveft after fetting in a raid or broaden than u(i|al; moqn bright, with iharp horns, after change; wind ftiifting to the eaft or north after change; iky full of twinking ftars; fmall clouds hovering low in the north; fnow falling fmall, while clouds appear on heaps like roclts. N. B. Frofts in autumn are always fucceeded with rain. ^ignt of Thaw. Snow falling in large flakes while the wind is at fouth; Thaw, cracks appearing in the ice ; fun looking waterith ; the moon's hornsblunted; (lars looking dull ; wind turning to the fouth; wind extremely ihifting ; it is alfo obferved, that, if 06lober and November be froft and fnow, January and February are ^ike to be open and mild. Signs of Drought. Fair weather for a week together, while the wind is all that Drought. iime in the fouth, is, for the mofl part, followed by a great drought; Pcflilential fcafons. 156 PB-OftNOSTlCS OF THE WEAT-HBR. drought; if February be for mofl rainy, fpring and furamer ' quarters are like to be fo too; but if it happen to be altogether fair, then expert a drought to follow; if lightning follow after twenty-four hours of dry and fair weather, drought will fol- low, but if within the twenty-four hours, exped great rains. Signs of Hard Winters. Hard winters. A moift and cold fummer, and mild autumn, are fure figns of a hard and fevere winter ; ftore of hips and haws denote the fame ; the hazel-tree flowering is ever obferved \o fore- tell the fame; acorns found without any infed is a fure prog- noftic of a hard winter. Signs of Pejiilential Seafons. A dry and cold winter with a foutherly wind; a very rriiny fpring, ficknefs in fummer'; if fummer be dry with the wind northerly but (he autumn rainy ard the wind foutherly, great ficknefs is likely to follow ; great heats in fpring time without winds; roots having a lufcious tafte, while the wind has beeri long foutherly without rain ; and laflly, great quantities of ftinking atoms, infefls or animals, as flies, frogs, fnakes, locufls, &c. Experiments of the Leech Worm. Leech worm. Inclofe the leech worm in an eight ounce vial glafs, three fourths filled with water covered with a bit of linen, let the water be changed once a week in fummer, and once a fort- night in winter. If the leech lies motionlefs at the bottom in a fpiral form, fair weather ; if crept to the top, rain ; if reftlefs, wind ; if very reftlefs, and without the water, thunder ; if in winter at bottom, froft; but, if in the winter it pitches its dwelling pn the mouth of the vial, fnow. Signs of Weather froni the Barometer.. Xarometer. In calm weather, when the air is inclined to rain, the mercury is low ; but when tending to fair, it will rife ; in very hot weather when falling, it forefhews thunder ; if rifing in winter, froft ; but, if falling in froft, thaw ; if rifing in a continued froft, fnow; if foul weather quickly on its falling, foon over; if fair weather quickly on its rifing, foon over ; alfo if rifing high in foul weather, and fo continuing for two or three days, before SIMPLE REPEATING WORK. 157 before the foul weather h over, then expe6l a continuance of fair weather ; but, if in fair weather the mercury fall low, and fo continue for two or three days, then expie^ much rain, and probably high winds. N, B. In an eaft wind, the mercury always rifes and falls loweft before great winds. XVI. A New, Cheap and Si7nple Apparatus for repeating the Hours, and Quarters in Clocks and Watches, By Mr, J.M. Elliot. Communicated by the Inventor, JL HE great expence of repeating watches in the firft pur- New and fimple chafe, as well as in the fubfequent repairs, have induced Mr. repeating mo- Elliot to turn his thoughts towards reducing their conftru6lion to a greater degree of (implicity, and confequently to dimi- nifh the charges in both thefe refpeds. In the mechanifm reprefented in plates VII. and VIII. the parts and their arrangement are fuch that without the ufual ap- paratus of pinions, pullies, chains, or racks, the watches re- peat both the hour and the quarters, viz. the hour firft and the _ quarter afterwards, or the hour or the quarters feparately; or ^ either of thefe firft as may be wilhed, without interruption, and by one hammer. As feveral of thefe pieces have been made and difpofed of in this country as well as exported, the pradlicability as well as the coft are both afcertained, which laft is about one third of the former charges. Plates VII. and VIII. reprefent the parts of this new ma- chinery. Fig. 1. fhews the principal pieces as attached to the upper pillar plate by means of a pottance A B C D, called the repeating pottance, kept to its place by the fcrew x, — a b fhews the pendant attached to a fteel axis upon which the repeating apparatus is fixed and carried. In the adual time piece thefe parts are as clofe to each other as convenience will allow ; but ihey are here reprefented for the fake of difiin6tnefs, as if at a difiance from each other. Tims, they are made to a6t and perform the ftriking by turning the axis of the pendant to the fight or left. c is a part of the bell feen edge wife, d and I are two arms «r pallets, which being fitted upon fquares on the axis are 4 moved I^g SIMPLE RBI^BAtiVG WORK. New and ftmpfe moved round whenever the axis i«? moved by means of tli^ grating mo- pendant. The firft d ferves to drive the work for ftriking the hour, and the latter / the work for the quarters. The firfl: of thefe apparatufes confifts of e the hour-locking fnail (fee alfo Fig. 2.) which is fitted on the axis by a round focket or pipe, upon which focket alfo is fixed (fteadily) the hour repeating wheel g [Fi'g- 1 and 2,) and (on a round part) the ratchet wheel h, which laft is drawn by a fpiral fpring ^ ^ in the di- reftion oppofite to that which is produced by the pallet d {Fig, 1 and 2) * is the hammer urged by its fpring t? outwards, and the defigncT has, I am forry to perceive, omitted to make a Iraall tail from the center pin near k towards g the hourrepeat-^ ing wheel. Now the a6tion of ftriking is firaply this ; when ' by turning the pendant exacts upon the fmall pin in e, the wheel g with its ratchet wheel A are carried round, and the teeth of g a6t on the tail of the hammer, and give more or fewer ftrokes, according to the number that pafs. The number is regulated thus, a {Fig. 4.) is the flar-wheel as ufual, and b the hour fnail fcrewed on the fame ; c is the click with its back fpring, and n 2 is the hour-locking lever, which terminates in an hook at z that maybe feen in Fig» 2. bearing againft the hour-locking fnail e. This hook will evi- dently be nearer to or farther from the axis of the locking-fnail e, according to the portion of the other end of the lever which bears again (1 the hour fnail b, and will confequently flop the pendant in its motion fooner or later by its oppofition to one of the flops of the fnail e. As the ftar wheel a is carried regu- larly round by the canon pinion as ufual, its fituation will de* termine the number of ftrokes. The inftant the pendant is let go, the fpring k a6ls upon the ratchet wheel, and reftores the original iituation ready fof iiriking again. After this account of the hours, the ftriking of the quarters will require little explanation, I [Fig. 1 and 5.) is the pallet or arm ading (by a reverfe motion of the pendant,) on the locking fnail in, which carries the contrate wheel p, for ftriking the quarters by its action, upon another tail r of tiie hammer ; and the original fituation is reftored by a ratchet wheel O and its fpring, {fee Fig. 6.) In Fig. 4-. is feen the quarter fnail ^ with its leVCr hk, who(e hook for regulating the number, may be feen at D in Fig. 5< and the fnail is prevented from going back by a fixed hook. 3 SCIENTIFIC SClENtlFlC NEWS. J59 I SCIENTIFIC NEWS. ly ^ Prize for the Artificial Compofition of Palladium. In confequence of the intimation received by the anonymous paper of which a copy is given in the laft number of this Journal, at page 75, I waited upon Mrs. Forfter, who per- fonally aflured me that (he holds the fum of twenty pounds, (which was paid to her by the fame unknown perfon who placed the palladium in her hands,) under the truftor engage- ment to pay the fame to the bearer of the certificate mentioned on the faid paper, at any time before Midfummer next; and that, if not claimed during that time, fhe fliall afterwards confider herfelf at liberty to repay the money when demanded by the fame unknown perfon. I have therefore requeued Charles Hatchett, Esq. F. R. S. and Edward Howard, Esq. F. R. S. to join myfelf as judges of the produ6l which may be made in our prefence, agreeably \^ to the before-mentioned paper ; to which propofal they have confented. And I have no doubt but that the commiffion will enable me to prefent to my readers an account of whatever may be the refultof this public invitation. Prize adjudged at the lajt Public Meeting of the National Inftitute'^. THE decree of the government, May the 2nd. 1803, that Annual prize for anthorized the Inftitute to accept the capital of 10000 franks, ^^emoftufeful [417o£'.] offered by Lalande, exprefles, " that, agreeably to the paper or oblerva- intention of the donor, the intereft ftiould be laid out annually ''°"* in a gold medal, which, or its value in money, (hould be given to the perfon, in France or elfewhere, the members of the Inflitute only excepted, who ftiould have made the ob- fervation, or written the memoir, that might appear moft conducive to the progrefs of aftronomy." Accordingly, on the report of the committee nominated for Decreed to the purpofe, the phylical and mathematical clafs decreed the ^'' 9'^^" ^°' prize 10 Dr. W. Olbers, for having difcovered, in the courfe a planet!^"' of the year 10, the planet to which aftronomers have given the name of pallas olherfiana. * La Decade Fhilofophique, No, Si). Julj- 1803. p. 142. the 2^Q SCIENTIFIC NEWS. The Dr's. merit Before this difcovery Dr. Olbers enjoyed conliderable re- asanaftronomer.p^jj^^j^^ among aflronomers, for a differtation on the moft eafy and commodious method of calculating the orbit of a comet ; and for the laborious calculations and obfervations he had made, to re-difcover Ceres, or Piazzi*s planet, which in faCl he did perceive, and was the firft to announce to us. Tei/lerian Society at Haarlem* Te\ferian fo- THIS fociety has propofed the following queftion: ■uSioiT'" *' ^^^ ''^^ application of pretended fupernatural principles to phyiics contributed to the progrefs of the fcience ? or does not the hiftory ot this fcience prove on the contrary, that all the progrefs made in natural philofophy has been owing to ob- fervations, experiments, ihe conclufions drawn from them, and mathematical calculations and dcmonftrations ?" The prize is a gold medal of the value of 400 florins (c£'40), and the anfwers to the quefiion, written in Dutch, Latin, French, Englidi, or German, maft be fent to the fociety be- fore the 1ft of April, ISOi. *^* r/if explanation of the fuhjecls of the queries of R. B, in our lafi, (page 7].) are deferred for imnt of room, * Iti Decnde Philofophiciuei No. 33. Anguft, 1802. p. 382. A JOURNAL OP Natural philosophy, chemistry, AND THE ARTS. MARCH, 1804. ARTICLE L t)€fcription of a new Steam Digefierfor Philofophical Refearches* By Sir A. N. Edelcrantz, Counfellor of the CJiancery, and private Secretary to the King of Sweden ; Member of the Szvedyh Academy, Sfc. SfC, Communicated by the Author* JL HE interelling and curious phenomena which this machine Excellence and prefented, from its firfl: difcovery by l'>pin, have always ren- "5'','^^ °^f *' dered it a defirable part of the chemical apparatus ; but the difficulties and dangers attending its ufe, have, at the fame time^ prevented its applications from being fo general, as the impor- tance of the obje6l feemed to promife. Many, and fome of i Ihem fuccefsful, attempts have been made to adapt this inftru- went to economical and culinary ufes; but thefe being com- monly limited within very few degrees of heat above the boiling point, fuch digefters> though they can be ufed with fafety, are at leaft inaccurate in the permanence, and uncertain in the determination of the elafticity and heat of the vapours a6ling in each experiment, which confequently cannot be either pre- cife or comparable with others : and though feveral ingenious philofophers, fuch as Watt, Betancourt, Smith of Geiflen, Van ImprovemenU - Marum, &c. have in later times very much improved their fcientific application, enough of imperfe6lion flill feems to remain to prevent their general ufe, and to afford fufEcient fcop« for. further improvements. Vol. VIL—Mari^h, 1804. M As 162 NEW STEAM DIGESTER. As long ago as the year 1793 I applied my thoughts to r«i* der this inftrument lefs imperfed, and though I cannot flatter niyfelf with having fucceeded in any confiderable degree, a (hort account of my attempts may not perhaps be thought quite ufelefs. The ufoal My firft obje6l was to obtain a perfect clofure for the digefter, clofwig the di- "'^'^'ch is necelTary not only for increafing the heat, but alfo for gefter is faulty preferring the contents. In former contrivances this has ge- in many ix- nerally been effefled by a metallic cover prefled on the top of the veflel by means of fcrews, wedges or other mechanical con- trivances, with a circular piece of leather, paper, or other foft material between both. I alfo tried thefe methods in a great variety of ways, but always found fuch covers either leaky, on applying moderate prelTures, or when the preflure was ftronger, too curaberfome for a courfe of varied and repeated experi- ments. Befides which, at the degree of 260 or 270® Fahr. the leather, as obferved before by Mr, Betancourt, is commonly decompofed or burnt, and linen or paper ceafe to clofe at a ftill lower temperature ; as foon as the moithire, they are imbibed New cover wilh becomes converted into vapour. I therefore ufed another jvhjch fits by a ^^y,^^ Qp a particular kind, confining of a thick circular plate, conical interior , ^ ' =» ^i • l furfacc, without With its edge turned conical, and grouud to fit exactly m the packing. under fide of a metallic ring of the fame conical form, folded to the mouth of the digefter, in which the plate was previoufly included. When the vefTel was ready for experiment and the plate lifted up fo as to apply to the ring, it clofed as exadly as could be defired, and the increafed force of the fteam, which tends to render other covers defective, had in this a contrary effedt. Two difficulties were thus overcome, that of a cura- berfome preffing apparatus, and the infufficiency of packings; but as the circular plate in this conftru6^:on w^as made to re- Inconvenlence main conftantly in the digefter, I found that though it was laid of this coutri- j^^^^ i]^q U jg of \i^ \^ fome experiments this mode was atteixled with an inconvenience which I was defirous of removing. I fucceeded by making another circular ring, turned with both fides conical, to be put between (he circular plate and the open- ing of the digefter, fitting exactly to each of them. This ring ab, Fig. 5. Plate iX. paftes over. the cover cd, when both are lowered, the, ring remaining in thedigeftor; but the circular plate is taken out through the enlarged opening ef. Though Iha4 vaoce« NEW STEAM DIGESTIR, 1(>3 I had by this contrivance,* in a great meafure diminiflied the inconveniences, yet the intermediate ring remaining in the veflel, and the increafed difficulty of executing a more com- plicated inftrument, urged me to attempt forae other more ex- peditious mode of clofing. I ftiould almoft be afliamed to confefs that the moft fimple simple and mod and, as I preCume, tiie be(> contrivance of all, did not occur accurate clofurc. to me before I had tried the more complicated ones ; if many refpedtable examples had not proved that the eaiieft and ftiorteft ^ method is often the moft difficult to find. The reafon is obvi- ous: Simplicity, like truth, is only one; the bye paths of error are ipnumerable. This method confifts in making the cover fimply an oblong, Defcrlptlon of fquare, or oval plane brafs plate^ accurately ground againft the the fame. It it inferior furfaceof a (imilar frame of the fame metal, fixed and fitsagainft a foldered to the opening of the digefter. This frame has an Surface within* oblong aperture, through which the cover may be put in or taken out at pleafure. When put in and prefTed gently againft the frame, it will by the means of a little oil,^ have adhefion enough to bear its own weight, till the fteam begins to a6t, which will clofe it perfe<5lly. But for greater fecurity afmall piece of wood, fixed with a fcrew, will keep the plate joined to the frame, and ferve at the fame time as a handle. Fig. 1» Plate IX. reprefents the longitudinal feflion of the whole in- ftrument, with all its parts; abh the covering plate, ground and fitted agaiuft a fquare metallic frame cd, foldered X to the veflel at c/, which ought to be made of hammered copper at leaft If line thick. Fi^, 2 is the tranfverfe fedionof the fame apparatus, and Fl^, 3. a plan of the brafs plate, where the dot- ted lines mark the opening of the frame c d, Fig. 1 . and the * The digefter with a conical plate, and the fafety-pifton defcribed below, firft executed in Stockholm, 1793, was exhibited to the members of the Royal Society in Berlin, in Feb. 1802j and a de- fcriptioitvof it, printed in the Obfervations Phyliques of Mr. Dela- metherie, Feb. 1803. t The different force of adhefion of the fame metal, in employ- ing different oils, is remarkable, and may afford a field for future ^nveftigation. X Befides foldering, the parts Ihould be joined together with rivets 9v fcrcws. M 2 pjtrt 164 lutvr STEAM ClGfistER. part covered by the fame. Fig, 4. h i is the wooclen handle turning round the fcrew g, Fig. 1 , 2. to conneft the metallic planes. It is a kind of button or key. Peculiar fafety My next objed \yas to render the inftrument fafe, and to ^h^^^^(T^^'*^^ place the operator's mind independent of any apprehenfion of he^egulatedr*^ ^^^^' accidents. For this purpofe, (befides the ftrength of the veflel and its different parts, which ought to be as folid as con- veniently can be made,) a metallic cylinder mn is fixed to the plate a 6, to the inferior open extremity of which a metallic fphere m b, perforated with fmall holes, adheres by mere fric- tion, allowing the vapour, but not the folid or, other matters, to pafs into the cylinder, which contains a folid pifton ko, made of the fame metal * and exa6tly ground into it, fo as to fink down by its own weight if lifted, without however permitting the vapour to efcape. This vapour when heated to a certain degree, will raife the pifton above one or more of the capillary holes 5 4", on the fide of the cylinder and then efcape. The pifton will remain ftationary or ofcillating at a height, where the quantity of fteam efcaping is equal to the quantity produced in the fame time by that fire, confequently at a low point if the fire is weak, or, if the fire is intenfe, at the top, where a larger hole prefents a compleat iflue to the fleam and prevents the poflibility of accidents. Conditions for To adapt the inftrument thus conftrucled to exa6l and cora- accurate experi- parative philofophical experiments, three things feem to be d?gefter. i. To ''^^"^''®^' ^' *^ afcertain the degree of heat of the interior know the tern- fluid contents f by a thermometer; 2. to increafe that heat at Trcommand p'^afure ; and 3, to fix it invariably, if it be defired, inde- the heat, and 3. pendent of the poffible increafe of the fire, during the courfe To render it of the experiment. itcady though • r r 11 • r 1 the fire be not The firft is obtained by means of ai fmall iron cup p q, fol- {°: dered into the plate, and containing fome mercury. A. fine ther- The temper- ^\ / , , , • ^ , - , , ature meafured mometer pafled through a cork, bemg fixed m the cup, the te^ * ermome- ^ Great care (liould be taken to make both of the fame metal, for in one inftance when I had the pifton made of the fame brafs with the cylinder, but of another day's cafting, this infinitely fmall dif- ference was ftillfuffieient to produce a different force of expanfion, in confequence whereof the pifton, which moved freely at 212% ceafed to move, and was quite fattened at 260'. f It is perhaps fuperfluous to obferve that a digeftor is only in- tended for experiments with fluids or bodies furrounded with them, and confequently never contains materials in a dry ftate. degree NEW STEAM DIGESTER. 16S «J, gives the variation or error in -, which error therefore increafes, co'teris paribus, a§ the fquare of the fecant of the latitude, fo that, on approaching the pole, it increafes without limit, and is ultimately infinite. Compa- rifons of this kind may therefore be expelled to give refults the more accurate the nearer they are to the equator, under which circle they will be the mod accurate of all. Here, again, however, another circumftance muft be taken into- confidera-* tion, viz, that the method of afcertaining the differences of longitude by the convergency of the meridians, fo convenient in furveys of this kind, is applicable only in high latitudes. In a trigonometrical furvey, therefore, of a country lying much farther fouth than Britain, a different method of afcertaining the longitudes of places muiJt neceflarily be adopted. 22. The J^gi INVESTIGATION OF CERTAIN THEOREMS To dctcriplne 22. The theorems, which were next propofed to be confi- the figuie of the^jg^gj ^^^ ^^^^ ^^^^ determine the figure of the earth from the earth trommea- ' ^ , , fures of the per- meaiures ot degrees ot the curve perpendicular to the meridian, pendicular in j^ different latitudes. For this purpofe let D' be a degree of tu4ci. *^"^ ^^ thefe curves, in the latitude ^', and D'^ a degree of one of them, in another latitude (p'\ Then c being the compreffion, . as before, we hav^ by § 18. ?«D'==a + c fin ^^', andalfo wD"= a + c fin *?)'V Hence m (D'- D'O = c (fin «(?)'- fin *(?''), and therefore c zz ^ ^^, - — r-rr.. This formula may be rendered more convenient for calcula* tion, by confidering that fin *^' = ~ , fo that fin *(?)'- fin *?)" = 1 - cof '^f?'- 1 + cof 20^" cof2(?)^^ cof2^'-. cof 2$'= 2 fin (^ + r) X fin ((f-?", wherefore fin 'ip'-fin ''?" = fin (', by (ubftituting for c, we have w(D'-D")fin*^ , '"^ =^^+fii.(^'+nxfin(^'-n* ^""^ ?»(D^-Dnfing(?) 24. Laftly, fince mD^ = o + c fin *$'', andwD'''=^ + cfin»r methods of Undiner ^ is to be preferred, under given circum- pe"'^"^"'''^ '" ^ a different htU fiances. Suppofe, for inftance, a degree of the curve perpen- '*^'^"* dicular to the meridian, in the latitude cp' to be D'', and a de* gree of the meridian itfelf in the fame latitude to be A' ; it is required to find in what other latitude (p'\ a degree D'^ per-. pendicular to the meridian, muft be meafured, in order that the comparifon of D' and D^', and of D' and A, may give values c of — , In which the probable error is the fame. Here, agreeably to an obfervation already made, we may. In c Older toeftimate the error produced in ^, in confequence of an error in the determination of D', and D'^, and A, fuppofe the error to afFe6t D'— D", or D'— D'' only, without paying any regard to the variation of D'' in the denominator. There- c D'— A fore, fjnce by ^ 18 we have - = —t~ ^r-— ,, and again by § 24, •^ ^ a 2iy cof *?> o J ^ c D'— D^** » ^ termining D'— A, and D'— D", and alfo that thefe are the only errors, their effeft will be the fame, in both cafes, if 2 cof ^— fin '^'' the quantity fought, and add cof ^'* to both fides of the preceding equation, then 3 cof *?>' = fin *(?)' + cof *(f)' - fin ^^'' = 1 - fin ^^p" = cof *'' therefore muft be fuch, that cof (p" ~ ^ 3 X cof ' — , — , the cofine of (p'^ will be ~ 1, and ^' therefore zz 0. Now, ^40 44' is the arch of which the cofine zz — rmearly, therefore if a degree of the meridian, and of the perpendicular to it, be meafured in latitude 54° 44-', the comparifon of thefe with one another will give a refult as accurate as if the degree of the perpendicular, in that latitude, were compared with the de-r gree at the equator, and more accurate of confequence, th^n if pny other degree of the perpendicular to the meridian, were to ^e CQinpared with D'« $6, Henc^ JYO INVESTIGATION OF CERTAIN THEOREMS. To determine 26. Hence, alfo, the comparifon of the degree of the mcri- the figure of the (Jlan, and of the perpendicular to it, in the fouth of England, is fares of the per- better than if a degree of the perpendicular meafured in that pendicular in latitude were compared with a degree at tiie equator. For if, tif«r'^''^" "' ^^'^ equation cof ^'^ rz (cof (?') X x/ 3, we make (p' ZZ 50^ 4-Vi (or any thing lefs than 54® 4V,) — fin *$') and thcreforci A a r D ~ A a 3a (fin ^?>- fin^^')* Now, it has been already fiiewn, that, by comparing D and D' we have — = — r-r — ttt-* Suppofing, therefore, equal er- a 2D' col *(f> « « o 1 rors to be committed in the determination of D — Aj and of RELATING TO THE FIGURE OF THE EARTH. 171 D'— D, and alfo paying no regard to the inequality of A afid D' in the denominators of thefe fra6lions, as it is notfo great as materially to affed the quantity that is fought for here, we Ihall have the errors in - nearly the fame in both formulas, when -- 3 fin *?>', or when 2 -• col ?)* = fin *?> — fin *(p', that is, adding cof *9 to both fides, - cof *?! n fin *

', and, therefore, - 5 5 -cof ^^Jzz 1 - fin *'zz cof *(?)', orcof 'zr (coftp) v'-. o »> 29. If, therefore, cofJpzZv/-* cof (p'ZI 1, that is 4] 'j then we will have (p^ z=. 35** 7^, fo that D muft be compared with a degree of the meridian as far fouth as 35^ 1', in order that the refult may be as good as when D and V>' are compared with one another. From this it is evident, that the method of comparing de- The former me- grees of the meridian, and perpendicular in the fame latitude, thod h preferable r , 1 •/•/>! /. , unlefs the degs. has even an advantage over the companion of degrees of the of the mer. be meridian in different latitudes, unlefs thefe lafi are taken at a^arafunder. confiderable difiance from one another. In this way may many ufeful conclufions be derived con- cerning the degree of credit due to meafurements already made, as well as with refpe6l to the feleiSlion of the places where they are to be made hereafter. On thefe I (hall enter The /ormermc- no further at prefent, and fiiall only add, that, befides the ad- ^hodalfo fup- vantages or diladvantages which the method of comparmg to- obfervers and gether degrees of the meridian and perpendicular in the fame *^ ^^'"^ inftra* latitude has, and which are fubje6ls of calculation, it has an- ' . other 272 INVESTIGATION OF CERTAIN THEOREMS, Other aHvantage, which in the cafe of theBritifli furvey is un- doubtedly very great, viz. that all the data arc furniflied from one fyftem of trigonometrical operations; executed according to the fame plan, with the fame inftruments, and by the fame obfervers. To determine 30. One other application of geometrical meafurements to die earth's difcover the figure of the earth yet remains to be confidered. ngure by com- . , . ■' paling an arc of This is the comparifon of an arch of the meridian with an arch the rr.er. with of a parallel of latitude which croffes it. The meafure of a {n fame lat. parallel of latitude can be executed readily, and is not confined to a fmall arch, as in the cafe of a perpendicular to the meri- dian. The plumb-line, while it is carried along the circum- ference of a parallel to the equator, tends continually to the fame point in the earth's axis, fo that there is no difficulty in afcertaining the amplitude of the arch meafured, providing there be no unufual difturbance of the dire6lion of gravity. As an arch of a parallel to the equator, however, is not the fliorteft line between two points on the furface of the fpheroid, the meafurement along that furface will not give the length of the arch truly. To obviate this difficulty, it is only necelTary to follow the method fo properly introduced into the TrigonomC'^ trical Survey, of reducing the meafures, both of lines and angles, to the chords and to the planes of the redilineal tri* angles contained by them. In this way, the chord of an arch of a parallel of latitude ipay be determined, however great the arch ; apd it is worthy of being remarked, that, whatever be the defle61ions of the plumb-line at the intermediate ftations, when the redu6lions are all properly made, the length of the chord meafured will not be aflfe6led by them ; the amplitude of the arch indeed may be aflfefled by fuch defle6tions, if they happen at its extremities ; but the eflfe^ of this error will b© rendered the lefs, the greater the arch that is meafured. We may fuppofe, therefore, that the chord of a large arch of a parallel of latitude is meafured, ar^d the amplitude of the arch itfelf {it the faiTie time accurately ^fcertained. This laft may ' be done, either by ipeafuring the convergency of the meridians, if it be in a high latitude, or by any other method of afcertain- ing diflferences of longitude which admits of great accuracy. The chord being thus given in fathoms, and the arch fubtended by it being given in degrees and minutes, the radius of the parallel itfelf becomes known, 3 J. NoW;, HfeLATMfG TO THE FIGi/rE OF THE eARTH. 173 31. Now, if we would compare the radius of a parallel thus To deftern&Ine found, with a large arch of the meridian, we fliall have by that ^^^u^^^^y c„„. means a determination of the figure of the earth, not lefs to be paring an arc of relied on than that given in the beginning of this paper, ^p /""• ^^ w i The inveftigation is eafy by help of the theorems in § 5 and 6. in fame lat. Let FO be the radius of a parallel to the equator, which palTes through F, the latitude of which is (p, and is fuppofed known ; and let FO found by the method juft defcribed be ~r, then^ . , a^ co( (p a cof (p* as m ^ 4. r zz — - ■ ■^=-. — ■ =-- ZZ . ^ v/«* coi'^ +^^ ii" ^- c fin «fin^». Let-l-=:/, then/ = a4-cfincp)2. col

{T^^}i attention (o thefe reflridions. Tlie gentleman, jiift namedl^ will forgive a remark, which I certainly fliould not have made, it I had been iefs iiUerefted for the fuccefs of the work, in which he has allifted with fo much ability* III. Enquiries concerning the Nature qf a Metallic Sahfiance lately fold in London as a new Metal, under the Title of Palladium, % Richard Chenevix, Esq. F. R, S. andM. R. I. A.* (Conclu ded frofn page 1 0 1 J kXPERIMENTS TO PROVE AFFINITY AMONG THE METALS, Inftances of Exp. 1. 1 dilTolved one hundred grains of filver in nitric affinity in metals ^p|(j^ g,-,(j precipitated by neutral muriate of platina. The by muriate of precipitate, well waflied and dried, was of a bright Uravv- platina carried colour, and weighed 147 grs. Reduced in a charcoal crucible, cent" of the* ^^ yielded a button weighing 121 grs. and of the fpecific gra- metal. vity of 1 1,6. The difference of weight, between the original hundred grains of filver and the 121, was owing to 21 grains of platina^ which had been drawn down irt precipitation along with the filver; by an affinity for that metal. This alloy is a6ted upon by nitric acid^ and a great part of the platina isdif- folved along with the filver, nor is it very eafy to feparate them , by the common methods. | Mercury and Exp. 2. I diffolved one hundfed grains of filver in nitric ii;ver precipitat- acid, and added about 1200 of mercury. I poured the mixed tv '" e^^fuu"^ folution into a folution of green fulphate of iron, and obtained phate. a very copious precipitate. When waflied and dried, it weigh- ed 939, and was a perfed amalgam, in the due proportion of mutual faturation. Its fpecific gravity was 13,2 j but no mer- cury remained with it after expofure to heat. Mercury and Exp. 3. I diffolved one hundred grains of gold in nltro^ gold precipitated muriatic acid, and added to it about 1200 grains of mercury^ gaveTfine bluT Green fulphate of iron, poured into this mixed folution, caufed metailic powder, a precipitate weighing 874. It was in the form of a fine blue powder, not refembling an amalgam, though wholly metallic Its fpecific giavity I could not afcertain ; but all the mercury was expelled by heat. - . The re-agents which I ufed in the following experiments, with recent mu- wcrc rccent muriate of tin, and green fulphate of iron. To riaie of tin, aud ^ brin2 t^RETENDED NEW METAL; PALLADIUM. 177 bring the examples of anomalous precipitations, in mixed fo- green fulphate Jutions of the metals, more clearly Into view> it will be ne-^ 'J^°"» *^ "' cefTary to ftate the adion of thefe falts, upon a folution of each metal when feparate. By recent muriate of tin we have, with a folution of ^old, Action of the the well known purple of Caffius. With platina, the coldiirof tj^oj^ ^1^, of the liquor is much heightened. With mercury, there is a tions of gold, total reduction. .With copper, a reduction from the black ^^^^y"^^'^"^"^^ oxide at 20 per cent, of oxigen, to the yellow oxide at 1 1 ,5 arienic acid, per cent, of oxigen. With arfenic acid, a redudion to the,^!^^^''' '^^'^» *"' ... . . . tirnony. ftate of white oxide. With filver, with lead, with antimony, no redudion. Green fulphate of iron reduces none of theof green fulpbate metallic folutions, except thofe of gold and filven ti on of gold and Wiien mixed folutions of the metals are expofed to the filver oniy. a6lion of recent muriate of tin, or of green fulphate of iron, we have the following refulls. Bxperiments 4, 5, 6, 7, and 8. Muriate of tin, poured into Exp. with mixed a mixed folution of gold and mercury, precipitates both metals ^^^ ^ ^^ ^.'j^ ^^ together; and there are no traces of the purple. Mixed fo- reagent, lutions of gold and antimony, alfo of gold and arfenic acid, are a6led upon in the fame manner. Mixed folutions of gold and copper, alfo of gold and lead, afford refults fimilar to thofe of each metal when feparate. Experiments 9, 10, 11, 12, and 13. With a folution of platina and arfenic acid, muriate of tin gives no precipitate; but the colour of the liquor is more heightened than if the platina had been alone in folution. Platina and antimony give a precipitate by this re-agent, after ftanding fome>time ; but the efFed is re- tarded by the excefs of acid in the folution of antimony. Pla- tina and copper, alfo platina and lead, are aded upon as the feparate folutions of thefe metals. Platina and filver are precipitated together by green fulphate of iron. Green fulphate Experiments 14, 15, 16. Mercury and copper, mercury arid lead, alfo mercury and arfenic, are precipitated in the metallic ftate by recent muriate of tin. ^ From thefe experiments it is evident, Ift. That gold has an affinity for mercury, for antimony Deduaiorsof and for arfenic. ' ^^f tlT"" gold and mcr- 2d. That platina has an affinity for filver, for mercury, and cury, antimony, for antimony: and that it is influenced by the prefence of*'"^^"l^'P^^'^'"* arlenic. cury, antimony} 3d. That filver has an affinity for mercury. f»Jver and mer- Vol. VII.~March, 1804. N ^^* Th^^Z\l^^^\Z, arfeni^ J78 ' PRETENDED NEW METAL; PALLADIUM. 4th. That mercury has an affinity for copper, for lead, and for arfenic. This feries of experiments is not intended as a fyftem of metallic affinities ; but as a few fa6ls ftated to corroborate an aflertion. I am well aware that many others might be noticed ; but it is not my intention to enter further into this fubjed, in the prefent paper. The general importance of the principle, and the extenfive influence it is likely to have upon chemiftry, demand that it fliould be treated by multiplied refearches. The experiments that can elucidate it are of the mofl delicate nature, and require peculiar care; for they do not always fucceed, unlefs performed under the mod favourable circum- flances. Mixed folutiona When mixed folutions of three or more metals are expofed , ^wo'^metat'L ^^ ^^^^ ^dion of recent muriate of tin, or of green fulphate of more ftriking iron, their a6lion upon each other appears in a much more *"e^xr°'^^ ^°"^' ^"^i"g* as alfo in a much more complicated point of view. EXPERIMENTS UPON PLATINA. Ixp. on platina. I ffiall now (late fome experiments which I have had occaiion to make upon platina, during the foregoing refearches. Very little is known concerning this metal, its oxides, or its falts; and, although I have not had occaiion to extend the enquiries very far, yet my experiments may ferve to eftablifti a few points. Platina diflblved I diflblved a quantity of puriHed platina* in nitro-muriatic ^Tlri'^V'''"^' acid, and precipitated by lime. A great portion of platina nitric acid } the remained in the liquor, although I had ufed an excefs of the acid expelled above earth. I rediflblved the precipitate in nitric acid, and by heat; oxide evaporated to drynefs. The refult was, a fubrtitrate of platina. reduced by f then expofcd the mafs, in a crucible, to a heat capable of Hinpeig 1 . g^pgiijpg the acid altogether ; and the oxide remained alone. When this was reddened, at a heat which certainly was not capable of melting filver, the oxide was reduced, and ap- peared with a metallic luftre. The weight of the various* * By purified platina, I have always underftood, in this Paper, platina reduced, at a gentle heat, from the fait obtained by pouring a CO! centrate folution of muriate of ammonia into a concentrate fo* lution of platina. produ^ PRETENDED NKW METAL; PALLADIUM. 179 products, in the above experiments, was fuch as to give the following proportions in the oxide, and the fubnitrate of platina. Yellow oxide of platina is compofed of, SnTpamTthe Platina ... 87 Oxigen - - - - I3 JOO. Subnitrate of platina is compofed of. The above oxide of platina - 89 Nitric acid and water - - - 1 1 oxide ; and of the fub* nitrate. 100. But, in the reduction of this oxide of platina, it became of a green colour ; and remained during forae time in that ftate. Nitrate of platina fometimes becomes of a pale green at the edges, when evaporated to drynefs ; and ammonia affumes a green colour when in holds oxide of platina in folution, as we have feen more particularly with palladium. This, therefore, is a fecond oxide of platina. It contains but feven per cent, of oxigen. \ diflblved a known portion of platina in nitro-muriatic acid, and expelled the nitric acid, by pouring in a fufficient quantity of the muriatic; and then evaporated to drynefs. By this expe- riment I learned, that the infoluble muriate of platina is com- pofed of. Yellow oxide of platina - - 70 Muriatic acid and water - - - 30 Two oxides of platina ; yellow with 13 per* cent, oxygen ; green with only 7 per. cent. Compon. parts of infoluble mu- riate of platina ; 100. I then expelled the muriatic acid by the fulphuric, and eva- porated again to drynefs. I found the infoluble fulphate of platina to be compofed of. Oxide of platina Acid and water 54,5 45,5 100,0. and of the in- foluble fulphatSi^ I By much the moft delicate teft for platina is muriate of tin. Munateoftln U A folution of the former, fo pale as hardly to be diilinguiftied f^a^f piatUm! from water, affumes a bright red by a fingle drop of the recenjt muriatic folution of the latter metal. If mercury be prefent, the colour is much darker. Recent muriate of tin, poured into a folution of the muriate formed by the red oxide of mercury, N 2 * converts 180 PRETENDED NEW METAL; PALLADIVM. The prufliates do not precip. platjna or mer- converls it into the muriate formed by the lefs oxigcnizcd acids; but, (hortly after, tlie mercury is reduced to the metallic ftate. Hence it was, that the alloy of platina and mercury always gave a deeper coloured precipitate than platina, with muriate of tin. Neither platina nor mercury are precipitated by pruffic acid or by the prufliates. But, if fulphate, nitrate, or muriate of eury fingly j but platina be poured into prufliate of mercury, an orange-coloured they do jointly, precipitate is immediately formed; and, in fomc cafes, a mixed folution of platina and mercury gives a fimilar pre- cipitate by pruffic acid alone. Platina is fimply Platina is one of the metals which are precipitated by ful-- hydrogen! "^ * phuretted hydrogen, without the neceffity of a double affinity. Order of affinities The affinities of platina differ much from what is generally •f^iua with ^^jgj i^ jj^g tables. By the few acids I have had occafion to try, oxide of platina is attraded in the following order: ful- phuric, oxalic, muriatic, phofphoric, fluoric, arfenic, tartaric, citric, benzoic, nitric, acetic, and boracic. That fulphuric acid fliould attrad the oxide of platina with greater force than the muriatic, is an unanfwerable argument to an opinion which was long fupported by many philofophers, and which is not yet altogether abandoned by them. Muriatic acid has been faid to contribute to the folution of gold or platina, in nitro. muriatic acid, in the fame manner as ful- phuric acid is fuppofed to promote the decompofition of water, during the folution of iron by that acid diluted. The affinity of muriatic acid for the oxide of gold or of platina, has been looked upon as the difpoling caufc that nitric acid is decom- pofed by thofe metals. But it is evident that fome other ac- tion takes place; for, fulphuric acid, which has a ftron^er affinity for oxide of platina frhian muriatic acid, does not in the leafl: promote the decompofition of nitric acid by gold, or bj platina. Remarkable theoretical oS fervatlon. CONCLUSION, ^ . ^ The fubflance which has been treated of in this paper, muft On the nature , , . . ^ , i r and ufc of convmce us how dangerous it is to form a theory before we are general hypothc- provided with a fufficient number of fa6ls, or to fubflitute the refults of a few obfervations, for the general laws of nature. If a theory is fometimes ufeful, as allandard to which we may refer our knowledge, it is at other times prejudicial, by creat- ing PRETENDED NEW METAL; PALLADIUM. 131 ing an attachment in our ralnds to preconceived ideas, which have been admitted without inquiring whether from truth or , from convenience. We eafily correct our judgment as to fafts; and the evidence of experiment is equally convincing to all perfons. But theories, not admitting of mathematical demonftration, and being but the interpretation of a feries of facts, are the creatures of opinion, and are governed by the various impreflions made upon every individual. Nature laughs at our fpeculations ; and though from time to time we receive fuch warnings as (hould awaken us to a due fenfe of our limited knowledge, we are prefented with an ample com- penfation, in the exteniion of our views, and a nearer ap- proach to immutable truth. The affinities of metals for each other are likely to be of the The affinity of moft extenfi ve inifluence in chemiftry. They will promote fcep- ©ther, fo ftrongly ticifm with regard to future difcoveries, and throw fome doubts Acwn in the upon our prefent knowledge. Palladium is certainly not lefs J[L^f„duce * different from the elements that corapofe it, and from all other doubts to the metals, thap any two can be from each other. Within the laft "f^ meta?*"^ fifteen or twenty years, feveral new metals and new earths have been made known to the world. The names that fupport thefe difcoveries are refpe6table, and the experiments decifive. If we do not give our aflent to them, no (ingle propofition in che- miftry can for a moment (land. But, whether all thefe are really fimple fubftances, or compounds not yet rcfolved into their elements, is what the authors themfelves cannot pofitively af- fert; nor wquld it in the lead diminifh the merit of their obfervations, if future experiments fliould prove them to have been miftaken, as to the fimplicity of thofe fubftances. This remark (liould not be confined to later difcoveries ; it ipay as; juflly be applied to thofe earths and metals with which we have been long acquainted. With regard to the melals, we have feen how little depend- Bilttle metals ance is to be placed on fpecific gravities. A contrary anomaly ft^f more fu»- to that which operates upon platina and mercury, jmay take pUfied. place in others ; af)d they may become as much heavier than the mean, as the former become lighter. In this flate of union, they may for a long time appear homogeneous, even by the teft of chemical re-agents. One of the properties that renders pietallic fubflances fo precious is, their eafy formation into fuch inftruments as our necefhties require. The fragile metals are but of fecondary confequepce; and, at molt, ferve to conf |g2 PREIENDED NEW METAL 5 PALLADIUM. on thufe which are du6lile, fome quality which adapts them better to particular purpofes. It often happens that, by being alloyed, two du6lile melals become fragile; but we have n6 inilance of the contrary efle6l in any high degree. It is there- fore more to be fuppofed that we (bould look to fimplification among the fragile melals ; and, even at this early period, it may not be too fpeculative to coniider the metallic bodies In an order which may bring together thofe which poflefs the greateii number of fimilar characters. Comparifons of ^g 3,^ inftance of this approximation, it may be obferved, metallic bodies . • , 1 , , i o . • . .1 c with this viewj ^^^^ nickel and cobalt Itrongly participate in the properties ot copper and iron. The two former metals were long regarded as mixtures; and the doubts of the ancient chemifts, who feared to pronounce as to their nature, may ftill be proved to have more foundation in truth than the aflTertion of the moderns, who have declared them to be fimpie. ACted upon by the fame menftrua, forming infoluble compounds with the fame acids, and foluble alike in other fubftances, they have but one or two marked properties that lead us to coniider tiiem as diftin5t metals. But palladium has at leaft live or fix characters, as Itrong as thofe of any metal whatfoever, that diftinguifli it, not only from its elements, but aifo from all other metals, and earthsalfo. Among the earths, this approximation is flill more apparent. A leading character of thefe fubftances is, their tendency to enter into faline combination, in which they receive new pro- perties, and perform new functions. If we rank them accord- ing to this general tendency, we fliall have the following order ; barytes and ftrontia; lime and magnefia; glucine and alumina ; zircon and lilica. And, if we confider them two by two in this order, which is a natural one, we lliall bring together precifely thofe which differ by the fmalleft number of chemical characters. Conclu£on. This inveftlgatlon might be purfned flill farther; but we rauft wait the refult of experiments ; a wide field is open for releafch. In the dark ages of cheraiflry, the objeCt was, to rival nature; and the fubftance which the adepts of thofe days were bulled to create, was univerfally allowed to be fimpie. In a more enlightened period, we have extended our enqui- ries, and multiplied the number of the elements. The laft talk will be to fimplify; and, by a clofer obfervation of nature, to learn from what a fmall liore of primitive materials, II that we behold and wonder at was created. IV. Obfervation I REMARKABLE STRATA OF FLINT. 183 IV. Ohfervations on fome remarkable Strata of Flint in a Chalk-Pit in the Jjle of Wight, in a Letter from ^zV Henry Charles Englefield, Bart. F. R. S, to John Latham, M. D, F.R.S,andL.S.* Dear Sir, J\s you confidered the fpecimens of flint which I (hewed Introduftory you worthy of the notice of the Linnean Society, I tranfmit^^^^'^^^'^^^"** them to you, together with fucb an account of the fituation in which I found them, as may perhaps lead to a guefs of the caufes of their prefent very extraordinary condition, and will at leaft ferve as a guide to thofe who may wifli at a future time to infpefl the curious pit where I found them. Before I enter on the particular defcription of that fpot, I cannot help faying a few words on the lithology of the ifland in general, which has not that I know of, been defcribed, as it highly deferves, by any naturalift. Had 1 been equal to fuch a talk, opportunities of obfervation were wanting, and the phenomenon which I am about to defcribe, was difcovered by me fo fliort a time before I quitted the ifland, that I had not time to infped more than one pit, befjdes that in which I obferved it. The Ifle of Wight, which is nearly of a rhomboidal form. Geological ac- lies with refpe<5t to its tour angles, almoft abfolutely in the four count of thMfl^ points of the compafs. It is divided into two very nearly * equal parts by a range of chalk hills, whofe general diredion "^ is due eaft and weft, Thefe hills do not, however, lie in a ftraight line, nor are they at all of equal breadth or height throughout their extent. At Bembridge, where they form the eaftern point of the ifland, they rife abruptly from the fea to the height of about 400 feet ; and bending a little to the northward, they continue of nearly the fame elevation, and a very narrow breadth, till they terminate at the valley through which the Medina runs. To the weft of the Medina the range grows confiderably wider and is fubdivided into feveral fubordinate vallies. This additional breadth gives the fouthern limit a great curvature to tlie fouth, while the northern line remains nearly ftraight. Their elevation increafes much, and at Mottifton is 700 feet. The acute and perpendicular , * From the Tranf. of the Linncjin Society, vol. IV, pronjontory 184- REMARKABLE STBATA OF FLINT. Geological 3c- promontory in which they terminate to the weft, well known cf Wight. ^y ^^® name of the Needles is nearly as high as Mottifton, Befide tl^ valley of the Medina, this range is Angularly in- terrupted by two vallies exaftly fimilar to eacfi other, at the two ends of the ifland. Brading Haven renders Yaverland at the eaft almoft an ifle, and the Yarmouth inlet cuts off the weftern end fo nearly, that at high tides it is quite infalated at freftiwater gate. To the north of this range of chalk hills the foil is chiefly clay, with a fuperftratum, in many parts of gravel, the clay is interfefted with many beds of ftone of different qualities, and which appear to lie in great confulion. Of thefo fome are grit with a flight admixture of calcareous matter, others have nearly equal parts of fand and lime, and others are purely calcareous. In the firft which are of great hardnefs, very few extraneous bodies appear. In the fecond, are many fine impreffions of fliells, while the laft are almoft entirely compofed of moulds of turbinated ftiells^ fo as to appear quite honeyrcombed by them. This ftone is however, of great durability for the walls of Cowes Caftle, which was built by Henry VIII. and is expofed to the fea air from the weft and north, are as perfedl as on the day in which they were built. Below all thefe ftrata of ftone at eaft Cowes, and juft above a bed of black and folid clay is a ftratura of (hells about two feet thick, of which a fpecimen accompanies this; and which is totally compofed of thefe Ihells without any admixture or earth whatfoever. As the Lea makes great inroads here, vail heaps of thefe ftiells He on the beach, and feem juft waftied up by the waves, inftead of being torn from their bed in the cliff*. They appear nearly in the fame ftate as thofe on the Hampfliire coaft, which have long been famous among na-^ turalifts. In the bed at eaft Cowes, there appears, however, no variety ; for I could fee no fpecies but what are here ex^ hibited. Whatever confufion in the ftrata appears to the north of the chalk range, or in that range itfelf, difappears to the fouth of it, where the ftrata are nearly in a horizontal pofition, and Angularly regular and undifturbed. The fea coaft from Bem-» bridge, fouth to the Needles, except in the fmall extent of Sanduwn Marfti, is every where higher than the immediately (optiguous land of the ifland, and to the fouth-eaft^ rifes into REMARKABLE STRATA OT FLINT. 185 a vaft range of hills running from Dunnofe weft to St. Catha- Geological ac- rines. The fubftratum oF theCe hills feem every where to ^J"^'^^^^^'- ^^*» be clay lying in ftrata of different colour and purity. The loweft is black and very hard ; approaching to (hale. Above this fome ftrata have a great mixture of fand, and take the appearance of a foft ftone, breaking into very regular cubical forms. Thefe ftrata extend over the whole fouthern part of the ifland, and terminate againft the chalk range very fuddenly. Above the clay ftrata is a bed of ftone in thin layers, and of very mingled materials, but in general very hard. Great quantities of chert or flint modules appear in this ftone. The general thicknefs of the ftratum is from 150 to 200 feet. Above this the higheft hills of the range have a ftratum of chalk, not pure or white as that of the chalk range properly fo called, nor producing flint fo black. The height of Dunnofe is 800 feet above low water mark, St. Catharine's hill is at leaft 850. Of the former I had no opportunity of examining accurately the thicknefs of the ftrata, but at St, Catharine's the ftrata are as follow. Chalk - 250 feet Stone - 200 feet, or perhaps not quite fo much Clay and Sand - 400 feet. 850. This arrangenient accounts entirely for the formation of that fingular coaft called the Underclifl^, which extends from Dunnofe to St. Catharine's ; and is compofed of the confufed fragments of the upper ftratum of rock, which have given way find rolled down, as the fubftratum of clay has been waflied •way by the fea. In moft parts the procefs feems nearly at a ftand ; the coaft being now prote6led by the fallen rocks ; but at St. Catharine's, great devaftation is ftill taking place. The earth-fall mentioned laft year, was a very fmall operation, when compared with the relics of former convulftons. From this fliort Iketch of the general pofition of the ftrata in the inland, I return to the particular fubjedl of the prefent paper. The chalk pit, which I am about to defcribe is fituated on Defcrlption of ? the northern edge of the chalk range juft out of the village of ^^'i^„P'' f^ ^ n 1 f 1 . 1 1 i 1 I . , .. .^ Caiiflbrook, Cantbrook, and about an hundred yards beyond the divifion with feams of pf the roads to Yarmouth and Shorvvell, The pit is open to ^'"> finguiarly ' , broken or "le Mattered, 1S6 REMARKABLE STRATA OP FLINT. the eaft. The ftrataof chalk are very regular from two to fivtf feet in thicknefs, and divided by Teams of flint from fix inches to nine inches in depth: The flints are as ufual in nodules of difl^erent fizes from the fize of the fift to twice the fizc of a man's head. The whole dip northward with an inclination of »t leaft 67 degrees. Perpendicular fiflures run through the whole from north to fouth, the tides of which are nearly at flat and fmooth as a wall. As thefe fiflures are followed with convenience ip working the pit, an extenfive face was laid open when I faw it, and the appearance was as in the annexed Iketch. See Plata XI. On examining the beds of flint nearly, I was aftoniflied to find that every flint, though lying in its place, and retaining perfeftly its original fliape, was more of lefs barft and fliattered, fome few were only fplit into large pieces, but the greater part were broken into fmall fragments, and fome abfolutely reduced to impalpable powder. From one which had fufl'ered the moft, the annexed fpecimen was taken. The powder was fo very fine that I conceived it muft have been mixed with chalk; but on wafliing it with diluted marine acid, I found that it was purely filiceous. Indeed the chalk which furrounds thefe flints is uncommonly folid, and does not exhibit cracks or marks of any violence except the great fif- fures before mentioned. A fpecimen of the flint powder after wafliing in the acid is fent with the other. I muft obferve that I had but an imperfect opportunity of in- fpefting the flints which lay at a diftancefrom the fiflure, fucb however as I could fee in the bed then working appeared to have been lefs fliattered in proportion as they were more remote from the fiflure, but all had fuffered more or lefs. About 200 yards below the pit, and nearer to Cariibrook village, the road is in part cut through the chalk, and the beds of flint expofed by that means exhibit the fame appearances as thofe in the pit above. Obfervaiions of The chalk pit above Shide Bridge, which is the only one I the flints in j^^^j ^^^ opportunity of examining after my difcovery of the phcenomenon above defcribed, prefents in fome degree the fame appearances, but does not aflbrd fo good an opportunity of viewing the ftrata as that at Cariftirook. The ftrata did not appear to me to lie fo regularly nor the flints to be difpofed fo much in beds as at Carifbrook. They were however ex- tremely 4 REMARKABLE STRATA OP FLINT. 187 tremely broken and (battered and apparently the moft fo where they lay moft in ftrata. The ftrata had alfo a great inclination or dip to the nortii. Although it would be rafli to attempt to account for this ver^ Conjeaure as to fingular ftate of deftrudion of the flints in the Caritbrook pit, thaulie^ftrala^'afe yet it is impoffible not to offer fome conje6lures on the fubjed. the period when There can be very little doubt tliat the ftrata though now fo ^^^'^ ^^^eTn^ inclined was originally formed in a horizontal pofition. When dined to flideon the tremendous convulfion took place which funk them to the each other, and , . » the flints were fituation m which they now appear (at which time the chan- crufliedby this nel which feparates the Ifle of Wight from the main land was enormous aftion. perhaps formed) the ftrata of chalk, in the a6t of fubfidence had a tendency to Aide on each other, and this would be exerted moft fenfibly where from the admixture of the flints the cohe- fion of the parts of the chalk was the weakeft. This motion or rather ftrain of fo enormous a weight might in an inftant fliiver the flints, though their refiftance ftopped the incipient motion, for the flints though cruflied to powder are not dif- placed, which muft have been the cafe had the beds flipped fenfibly. This conje6lure is perhaps ftrengthened by what I obferved in a few detached nodules of flint in the chalk ftrata which did not appear to have fuffered as thofe in the beds of flint have done. I may here add that it feemed as if in fome places the fine powder of the flints had run down, and inveft- ed the nearer parts of the fiflTure with a thin coating of the agglutinated duft; but this may poffibly have taken place fince the face of the filfure has been expofed to the weather. Perhaps it may not be totally foreign from the prefent fub- Appearances of jea to mention that in a very great chalk pit at the village of gJj^J^JfjPjjJjj^^" Prefton, a mile north of Brighthelmftone, in which the flints lie ftone. in a very regular and nearly horizontal ftrata, but which has alfo vaft perpendicular fiflfures in the chalk ; the fiflures are in many places filled to a confiderable extent with a very thin vein of pure flint exaflly as if the flint, not being quite hard when the fiflfures took place, had been fqueezed out of the beds and run into the fifllires as foft pitch would do. I do not mean at all to fay that this was the cafe, but merely todefcribe the appearances. In the chalk pit juft below the church at Brighthelmftone another fingular appearance may be feen. The upper part of the chalk is in feparate mafles, not properly rubble, but with all their tender angles ftiarp exadly as if juft broken J88 ^^W MERCURIAL AlH-WMT, broken to pieces to put into the lime kiln, and quite clean, nearly of a fjze, and alraolt without any chalk powder mixed with them. I remain, &c. Sorcthampton, Jan, 22, 1 800. V. Defer iption of a mercurial Air-pump, of unlimited exhavjiing Poiver, with a Wooden Pijton, working in a Wooden Cylinder, ^ Sfc, By Sir A, N. Edelcrantz, 4^* ^c. Communicated by the Author, ConftruAion of aIaVING refided a long time in a place, where no ma* •n air pump in thematical inftrument maker could be had, I was obliged to 4ualfpace is left, contrive fome method of conftruding an air-pump, in which common workmen and common materials could be er^ployed, Beiides which, as in almoft all former conftrudions of this in-. iirument, a fmall fpace exifls in fome part of them, where the air remains condenfed, &nd confequently a limit is fixed to the expanfion, I was defirous, if poffible, to remove this feemingly material, though in good pumps infinitely fmall defed. Thefe confiderations led me many years ago to a contrivance, of which the following fliort defcription may give a notion, referving a, more detailed one, with a more particular account of its effeds, to a future publication. Defcription with A B C D, Plate XII. is a folid piflon of wood, cylindrical or a drawing. fquare, * moving up and down in a fimilar wooden box or tube. It operates by ^ * » * ' mercury raifed E F G H, by means of rack-work at H. The pifton fills the and lowered m a ^^^ j„ j^g whole length as exadly as poffible, without touching wooden pipe, by . -.-^. -oi^i -r. i r i a plug, and the and producmg friction agamit the tides. i*or that purpole the upper communi- pjfton is guided at the lower end by an iron rod KI, fixed in receiver is made ^^^^ bottoiTi of the box and entering the pifron, and at its upper through ati iron part by a roller, which runs along the inner furface of the bar- *^°^ * rel. The cavity of the wooden box extends through the canal F Mf to the iron cock O, and communicates at M with a per- * I have, m the execution, preferred the fquare form, as raor« eafy to make exaft and equal in its whole length* f All the wooden parts are made of ftrong oak, and are covered with a good refinous yanViQi, to prevent the ahforption of mercury: pepdicular KEW mercurial AIR-^UMP. 189 pendicular glafs tube M N and the glafs fphere P» This fphere Air pump oper- is conne6led with an iron cock Q R, having two oppofite per- cut7 i/a wood* forations, one going horizontally to R, where a fmall outfideen barrel, &c« valve permits a communication with the glafs ball SY; the other, placed perpendicularly, opens a pafiage from the com- mon receiver VT to the fphere. The inftrument being thus conftruded, the box HEFG, is filled with mercury to the dot- ted line a a, or about fix inches, and the pifton being alter- nately preffed down or raifed as ufual by the crank work, the effedl of the machine is as follows: The cock Q R being turned as in the figure, the communi- cation with the receiver is fliut, and that with the external air, through a fmall hole S in the glafs fphere S Y, being open, the pifton in defcending prefTes upon the farface a a, and forces the mercury out of its place, it confequently rifes in the fmall fpace between the piflon and the wooden tube, a a to bb, and at the fame time in the glafs tube N P to a correfponding height N. The prefTure being continued, the mercury flill rifes fo as to fill the whole tube, the fphere P, and laft of all makes its way through the cock Q R and the valve R. forcing every particle of the air contained in M N P out before it. When a drop of mercury appears in Y, the piflon is moved the contrary way, and by its afcenfion the prefTure on the mercury is diminifhed, which finks and evacuates the fphere P, leaving a place for the air from the receiver which is admitted by turning the cock Q R, in the other diredlion *. P being filled with air, the * cock is turned again, the piflon again defcends, and expels the air, by raifing the mercury a fecond time, and in this manner the exhauflion may be continued at pleafure ; The raechanifm and efFed of this inflrument being, as I prefume, rendered clear by the preceding defcription, I fhall only add a few re- marks. The necefTary force to prefs down the piflon, being a little more than the whole weight of a column of mercury of the bafis D C, and the height of the barometer, is confiderable in the beginning of the operation, but diminifhes as in other air- pumps, when the air in the receiver becomes more rarefied ; when the external atmofphere afls more powerfully in fupport • The alternate turnings of the cock may eafily be performed by a fimple appendage conne^ed with the motion of the piflon. 2 of 190 N^W MERCURIAL AIR-PUMP. Air pump oper- of the column M N, which in every fiicceffive flroke becomes cu"^i/a"wood- ^'8^*^'"» ^''' ^^^ exhauftion is nearly coinpleat, when its height rn barrel, &c. will be that of the barometer. In order to equalize the preffing force more nearly during the whole operation, the upper end of the pilton may be loaded with a weight equal to half the original prefliire. The mercury being a fluid, fills every angular fpace as it pafles, till it opens its way through the valve R; confequently no particle of air can be left in a condenfed ftate to be more rarified or diminillied by the next ftroke of the pifton. By this means the common defefl of air-pumps feeras to be remedied, and the exhauftion unlimited. Belides, as neither moifture or oil are introduced in this pump, the vapours arifing from them in great exhauftions are prevented. The quantity of mercury required, when the diameter of the wooden box and of the fphere P are four inches, will be about fixty pounds, which if taken out by the cock O, may ferve alfo for another ufeful apparatus in the fame laboratory: the mercurial air holder. Several projects for mercurial air-pumps have been publifhed before, although I think none executed; but a comparifon will, as I fuppofe, ealily ftiew this conftrudion to be quite different from any of them. For greater foUdity, I have in the execution made three- fourths of the tube M P of iron. The fphere P is hkewife fixed and faftened by means not fliewn in the figure, but which may without dilTiculty be apprehended. Excepting the cock Q R, which requires fome precifion of workmanfliip, all the parts of the machine may be executed by common workmen, fucb as carpenters, fraiths, &c. who ar«i^ every where to be found. VI. On; SUFPLY OF WORM TUBS BY THE SYPHON. ' 191 VL On the Comhin/ilions for fupplj/ing Worm Tubs ztith Cold Water, by the Syphon, tilth an eajy Method of fecuring the Joints of . fuch Hj/draulic Apparatus againjl the Adtnijjlonnf the External Air. In a Letter from Mr. Wm. Close. To Mr. NICHOLSON. SIR Dalton,Feb. 13, 1804. 1 HE combinations which have lately appeared in your Jour- ^^^'f"'? *^y. nal, for fupplying worm tubs, condenfers, &c. with cold water, dplejsajjplica- have recalled my attention to certain experiments which I tor- b!e to the fupply merly made with the fyphon; and I am of opinion that the |^^^ "^ '" "' method propofed will fucceed very well upon the fimple con- ftrudlion of the apparatus delineated in Plate IV. Vol. VI. of your Journal, if all the parts are made air-tight, and a fufHcient ^ quantity of water be provided to keep the fyphon in conttant adlion, under an impending column of two feet. For the air difengaged from the water in the worm-tub will rife into the bend of the fyphon at B. Plate IV. Vol. VI. and be carried down the defcending column and emitted at C. The worm tub may be effedually fecured againft the admif- Eafy method of fion of the external air through the joinings of the ftaves, by "(g^'^'^f-^ u being placed in a larger tub filled with water; no air then can furrounding th© poffibly enter the interior tub fo long as it is covered, and the ^^"""^ ^^^ ^'^** workmanfhip muft be very bad, if the fyphon (hould draw the water out of the exterior velTel, fo faft as to produce any in- convenience in replenilhing it as often as it fubfides. The worm mull be made air-tight before it is fixed in its To fet the ma- I place. If the fupply of cold water at A fhould be interrupt- ^he"n ^^"^^^ cd, the fluid in A will fubfide to a level with the furface of C, and, if much air be difengaged during this fufpenfion, and while the water is impending in the apparatus, the fyphon will probably not refume its operation : In this cafe the two aper- tures muft be clofed, and the apparatus filled with water. You will remember the principles on which I planned the Account of the conftrudion of a machine for raifing water by the fyphon. I phon engine for- liave the complete model of fuch a machine : it has four light, ""^'^X defcribcil. felf-a6iing valves, and when thefe are not prevented from jcjofin^, by impurities in the w^ter, &c. it perfornjs very well. The 192 - «Ui»PLY 6t WdRM TUBS BY fPIE sVi^HOT^* The fyphon is not quite two inches wide ; it fifes abojit ^4 inches above the refervoir in which it is placed, and the de* fcending column is fix inches longer than the afcending one. The machine is conftrucled with all the parts reprefented in Flatc III. Vol. I. but under a different arrangement. It deli- vers about three pints of water every minute, at 31 inches above the refervoir : the alternations are repeated every five feconds. Its power In In the operation of this machine, a bulk of air equal to Mrryirigdown ^j^^gg -^mi^ of water is carried down the defcending column every minute, when the fall i§ only fix inches ; but I am cer- tain from experiment that the fyphon would clear itfelf of a much greater bulk in the fame time. Hertce the In an experiment on the 29th of May 1802, with a fyphon worm tub fy- ^f the above dimenfions, and a fall of fix inches, it appeared effedual In car- by a graduated bottle which received the raifed water, that the ryingoffthe fyphon would take a quantity of air equal in bulk to four from^the water, ounces of water at leaft, every three feconds. I think, there- fore, that the fmall quantity of air which will be difengaged from the water in the worm tub at a low temperature, by the operation of the fyphon, with a fall of two or three feet, will be carrieJ off as fall as it is produced, unlefs the pipe be very narrow in proportion to the tub, I am. Sir, Your*s refpeclfully, WILLIAM CLOSE. VII. An Anfzver to Dr. Wollaston*s Statement, " Of an Im- provement in the Form of Spedacle-Glaffes ." By Mr, VfiL* L I A M Jo N E s , F. Am.P.S, Optician, Holborn, Tbefpeaaclc ObSERVING in your Journal for laft Months that Dr. glafles of Dr. W. H. Wollafion, by a paper inferted therein, is attempting wnfured!" *° introduce into the conftruaion of fpedacles, the well known and obfolete form of leps called a menifcus ; I beg leave. Sir, to offer through the channel of your fcientific and impartial record, a few obfervations on his arguments ; and my reafons why I do not confider the contrivance as entitled to any claim either of novelty or improvement. Wheu-i REMARKS ON SPECTACLES. 193 When a printed book, or other obieft, is received through Aberration of ro, . r , , r\ r ..-n light refrafted a convex Ipectacle-glais, or other lensot a Ihort local diltance, ^y lenf«s. fuch as from feven inches down to four inches or lefs, the in- diftinflnefs obferved of the furrounding parts, when the central appear diftincl, arifes from the fpherical figure of the lens, and is by Opticians called the longitudinal aberration of the lens. There is another kind of aberration connected with this lens, called the lateral aberration, which is occafioned by the prifraatic form of the lens, producing different refrangibility of the rays of light, and blending the prifmatic colours with the appearance of the obje6l. It is the longitudinal aberra- tion only that I have now occafion to confider. This aberra- tion in lenfes of the Time foci, increafes with the diameter and thicknefs; and of the fame diameter is in the inverfe pra« portion to the foci. The rays ilTuing from diftant objecls, are more parallel to each other when incident upon the lens, than thofe from proximate ones; therefore the aberration will be lefs. Hence, it may be inferred, tliat when fpedtacle-glafles have Contradlng th« been made larger in diameter than is fufficient to obferve i'^^^"~J f. through, the angular extent of obje61s have very properly been approved. fomewhat reduced in diameter, fo that a perfon might ufe them without much inclining the axis of his eyes, or finding it inconvenient or unnatural to move his head a little. For the aberration is thus diminiflied, and confequenfly the objedlion in a great degree removed, except when the glafles are of ; • ' ;• very lliort foci. In concave glafles, the aberration or indiftindnefs is of a Concaves, fimilar nature ; the defe6l of thefe being from the imperfect divergence of the rays, inftead of the imperfect convergence in convex glalfes. Spedlacle-glafTes are now generally made of the double Remarks on concave, and double convex forms or nearly fo : for a little !^P^'^^*^l*^V".^ . 1. .. ^ f. , ^ ^ , , fo"i2 ot *he im* alteration ot hgure does not affed the general appearance of provements objedts viewed through thenj. It is in fcience, as in other "^^'^^ ^" ^*^« ^* cafes, that general utility does not always depend on trifling alterations. Spedacles are recorded to have been invented about the year 1300, and from much reading and many years experience in this fmall, but invaluable article, I really do not know, that during the elapfed time, any optical inflrument ' y of any kind whatfoever has undergone more innovation, and Vol. VII. —March, ISOI. Q attempti 194, The original form moft ap- proved. Theorem of Huygens con- jfideied as unlverfally ap< pUcabl^ Eye glaffes of fpe£tacles. Remarks on Jfcnfes ; to af- certain the value of Dr. Wollafton's patent fpec- REMARKS ON SPECTACLES. attempts at improvement. Of many within my knowledge^ I (hall only (ele€t the following as entitled to any degree of commendation. /Ij/fcough's crown glafs fpeflacles. The bi- fe6ted glaflfes of Dr. Franklin. Rihright's double glalTes. The vifual glafl'es of that learned Optician Mr. Martin. The fquare convex form by Siour. The patent combined glalfes of Meflrs. Watkins and Smitli, injudicioufly called achromatic, confifring of a convex lens, combined with a menifcus or con- cave convex lens. In tlie various mountings of the fram«sS there is a flill greater variety. Notwithrtanding Ihefe contrivances, univerfal experience has caufed the original and iimple form of glalfes to fuperfedo them; and it affords an indubitable proof, that it is the belt and moft converiient that can be dcvifcd, when clear glals, accurate tools, and good workmanOiip are ufed. The theorem given by Ilui/gemj and demonftrated by many other fubfequent writers on optics, proving that a convex lens having its radii of cuivature in the proportion of one to fix, has lefs aberration than any other form of lens, when the greateft convexity is towards the obje6l; and the fame for the concave lens ; mud hold true fpr any ufe whatfoever, for which fuch a ibrmed lens may be required. It does not appear to have occurred to Dr. W. that the eye glalTes ufed to magnify the images formed by the object glaifes in teiefcopes are of the beft form, when with the curves of the proportion above mentioned. In the eye pieces of the beft achromatic teiefcopes, they are always applied, and in high powers, the image frequently fubtends an angle from the centre of the eye glafs of fixty degrees or more. I have never feen any corre^i dioptrical theorem, that tended to prove that a menifcus, fingly, or combined, will anfwer fo per- fectly the fame purpofe. The ordinary purpofes of vifion, are very well anfwered by the common glafl'es, under an angle as large as eighty or ninety degrees, and the beft artifts, or draughtfmen allow^ that 60^ is as much as a fixed pofilion of the eye ought in perfpective to embrace, to convey a juft reprcfentation on the optic nerve. To perfons, the humours of whofe eyes are fo decayed as lo be deficient in their original refradlive power, glalfes of fliort i'oci REMARKS O^ SPECTACLES. 195 foci will, to them, render the extreme parts of objefls fome- Remarks on what confufed; but in a raucli lefs degree than to perfons, with certam thecal uc perfect eyes, or undecayed humours. of Dr. Wolla- In telefcopes and microfcopes, the aberration is "dually cut ^"'^^jat^nt off by the infertion of circular apertures or flops; but in fpec- tacles this is not eflenlially neceffary, nor does the want of them or the figure of ihe glafles, prove that they are con- ftitutionally bad and prejudicial. ' The obfervation of Dr. W. that only a portion of the glafs a little larger than the pupil of the eye, is employed at once, is onlyjuft inafmuch as it relates to the mind, being intent on a point of an objed ; but not fo in regard to a general view. For the refra6tive power of the lens does moft admirably colledt all the infinite number of pencils of rays, or cones, into one concurrence at the pupil of the eye ; where they crofs or in- terfe6l each other : yet, fuch is the exquifite fubtilty of light that no confufion or irritation takes place. Man is thus bletfed by affifled vifion, as he is in vitality by the refpiration of air. Dr. W*s inferring the form of a menifcus from the (hape of a globe, is manifeftly erroneous ; and in refpe6t to fpe6tacles in« appropriate. A glafs globe or fphere without any fenlible thicknefs, to an eye exa6lly placed in its centre, admits all the incident rays to pafs throughout it unrefracled. If the eye deviates from the centre, a refradion will take place, and that in proportion to the thicknefs of the fphere. Rays of in- cidence pafs perfedly unrefradled through truly ground plane, or parallel glafs, to an eye before k ; and let the axis of the eye, be ever fo much inclofed, unlefs the glafs be very thick, the obje6t will ftill appear perfed, and no refraclion of the incident rays will be obferved. It is obvious, therefore, the nearer a lens approaches to the figure of a plane, the more perfect it mufl: be. The figure of a menifcus, which Dr. W. withes to adopt, is as different from a fphere, as a plane. Its figure is com^ pofed of two portions of fpheres, of different radii. When with a pofitive focus it is mathematically demonftrable, that it has entirely the properties of a convex lens, and with a negative focus the properties of a concave one. When the radius of the exterior curve, is lefs than that of the interior it is a convex fort of lens, and magnifies; but, when the radius of the interior curve is lefs than that of the other, it is 02 a con- 196 REMARKS ON SPECTACLES. ^ Remarks on a concave Icn?, and diminifbes. It has alfo been demonftraled, Jenfes} to al- ,1,1 1 r r •/• 1 /• certain the valve "1^* '"^ nearer the form of a menilcus approaches to that or a of Dr. Wolla- plano convex or concave, the more perfeft it will be, and fton's patent 1 1 r 1 • fpcdlaclcs. produce lets aberration. I ftiall difpenfe here with the proofs by algebraical and analytical formulas, as any qualified reader will find them in the optical works of Huygem, Molineux, Euler, D*Alembert, Smith, Emerfon and Martin ; and many others. The rays of light ifluing from a near objed to a fpedacle glafs before the eye, are in diverging pencils or cones, and the menifcus form of glafs of any certain pofitive focus, will refract them towards a flate of parallelifm into the eye, necef- fary to produce ditlind vifion, in decayed fight, pre- cifely in the fame manner as a double convex or piano convex glafs of the fame focus would do. A menifcus with a negative focus, ads no ways diflferent from the double or piano concave glatfes; the rays of light being divergent fomewhat to coun- teract the eflfeds of too great a convexity in the humours of the eye of a ftiort fighted perfon. Perhaps, it is hardly neceffary to obferve, that imperfe6l vifion in the optical fenfe, confifis in the long fighted eye, in the rays of light not being fufficiently converged by its humours, to meet on the retina of the eye, but falling beyond it ; and in a fliort fighted eye by the rays converging too much, fo as to meet before they reach the retina. Varying the geometrical figure of a lens, does not con- ftitute any new optical principle, for any of the common fpecies of lenfes, may be cut into the form of a fquare, a triangle, an oval, &c.*all figuratively various, but confifting only of one optical principle. The ufe of the menifcus has been abandoned by Opticians, by its containing in comparifon with other lenfes, the greatefi: fpherical furface, and confequently producing the greatell aberration. Reducing the curvatures of the menifcus elongates the focus, in the fame manner as in other lenfes, and there- fore reduces the aberration. Hence in fpedacle-glalfes that are not of fliort foci, no preceptible diflference will be found » to perfons unacquainted with optical experiments. There are various pradtical methods that will point out to perfons the aberration of lenfes here fpoken of, and that the minifcus REMARKS ON SPECTACLES. 197 meniTcus caufes thegreatefl of any of the other forms of lenfes ; j^^^g^';''^^^''"^^ but, the following, 1 would recommend as the mod eafy and certain the valve illuftrative. ofDr.Wolla- Take a menifcus lens about the fize of a fpe6lacle-glafs, fpe^adcj^"^ and with four inches pofitive focus, and take alfo a piano con- vex or a double convex, of the fame diameter and focus, in a room with one lighted candle, at a diftance by night, hold the convex glafs near to the white wall or wainfcot fide of theroom, between itandthecandle;movethelens backwards andforwards till a clear image of the candle is formed, which will beadiftin^ inverted image of it; do the fame with a menifcus, and there will be this difference obferved by the menifcus, that incir- cling the vivid image of the flame, there will be a faint white light, which is the circle of the aberration ; and, evidently fliews, that it is the worft form of the two for a fpedacle- glafs, or any other purpofe. Two convex double glalTes placed together in one cell, contain lefs aberration than one glafs of the fame diameter and focus ; and two piano convex-glafles with their convex fides placed together in one cell, give ftill lefs aberration. It is lofs of light only that can be objected to. They are too weighty to be adopted in fpedacles, but in eye pieces of large telefcopes for viewing celeflial obje6ts, they have been ufed * with great advantage. To engravers, miniature painters, and other artifls, they are moft ufeful, as by (hort foci and large apertures, they give them the moft diflin6l view of a large furface placed before them. For the fatisfadion of an intelligent perfon, who may be difpofed to have an ocular proof of the properties of glalTes as herein advanced, I have confl:ru6ted a frame, containing a i double convex, piano convex, a menifcus, two piano con- I vexes, with their convex fides to each other, all of the fame diameter, and the foci about four inches, and by which may be feen that the greateft peripheretical indifiin6lnefs is with the menifcus glafs. This apparatus will be fliewn by ap- plication at our manufaftory in Holborn, The menifcus as a figure for a fpe6tacle glafs I conlider very objedionable. To afford a large field of view, its diameter muft be confiderable; which for a (hort focus will increafe thicknef-?, protuberance outwards, and weight; and, in con- cave glaflTes occafion the frames to be made thicker; theglalTes Will 1^8 OCCULTATION OF A STAR BY MARS. will be more liable to be fcratclied and broken than thofe of the common form, and when the frames are metallic, more likely to increafe than diminifli tliat indelible mark made on the nofe by the weight of the frame, fo frequently complained of by perfons who wear fpedlacles almoft conftanlly. A great deal of fuperfluous light alfo paffing through the glafTes, mufl be evidently prejudicial; and, it appears to me that the con-» cave figure of the inner fide of the menifcus will a6t as a powerful reflector to condenfe the rays of light and heat upon the eyes, and ultimately prove thereby of ferious injury. I have in my pofTeffion a menifcus I'pedacle glafs, taken from a fpeiftacle frame, which 1 can prove to have been made many years ago; and, finally, as this form is neither new in principle, or in practice, I am at a jofs to know upon what fort of difcovcry his Majefly^s letters patent have been fo- licited. ' I am, I Sir, Tour's, &c. W. JONES. VIIL Jn Account of an Occultation of b Nebulae Sagittarii, by the Planet Mars, on the 17 th of April 1796, obferved by Sir Henry Englefield, Bart. F, U. S. In a Letter aiU drejjcd to the Rev. Nevil MaskeIkYNe, />. D. f. R. S, and Jftronomer Royal, * DEAR SIR bccukatiou of a J[ BEG leave to communicate to you an obfervation, which planetMarsV ^ ^ ^^^ ^^'^ g^^^^ fortune to make, of an occultation of a fixed flar by the planet Mars ; and which, as far as lean learn, was feeii by nobody in this country but myfelf and Lady Buck, at whofe houfe at Peterfliam I made the obfervation, and to whom I fliowed the planet when nearly approaching to con- jun6iion with the ftar. •Thefe obfervn- Obfervations of this kind may be ranked ^mong the rareft tions are very phenomena in afironomy. Mr. De La Lande records but jarc. * ♦ From the Journals of the Royal Inilitution, No. 16, p. 38* four 6CCULTATI0N OF A STAR BY MARS^ 19^ Four fince ibe invention of telefcopes. Of thefe, one only is by Mars, and that fo long ago as about the year 1630, by Gaflendi. The curious and very important conjun6lion of Mars with pli aquarii, in 06lober 1672, whence Caffini had hoped to deduce, with great accuracy, the parallax of Mars and the Sun, was miffed by bad weather at the moment of the occultation. Since that time, I do not know that any ob- fervation of this kind has been made. The night of April 17, 1796, being very clear, I was led Account of the by mere accident to diredl my telefcope to Mars, about two*'^^^'^^^^°"* o'clock in the morning ; and I faw with equal pleafure and furprife, a liar, about three of his diameters to the eaft of him, and in a line perpendicular to his horns, he being then gibbous. It was evident that an occultation would take place, and I prepared every thing for the obfervation. The telefcope I ufed is an achromatic of Ramfden, the InftrumentSs aperture 2.7Ji, with a (ingle eye-glafs, magnifying 100 times. The clock is a very good regulator, with a wooden pendulum, and to be depended on to lefs than 2 feconds in the 24 hours. « The obfervations for the time were made with an excellent fix incii Hadley's fextant of Ramfden's, and an artificial horizon of mercury. The pofition of Peterfham, as deduced by a furvey made Place of the oWi by me fome years fince, from the Royal Obfervatory at Kew, which was one of the points fettled by General Roy in his great furvey, U U \Q!' in time weft of the Obfervatory at Greenwich in longitude j and its latitude by the fame furvey 51°26'31.^ To return to the obfervation. The Iky, during the whole Collateral cir- time, was perfedly free from clouds, but was remarkably full «"n^^a"««« of vapours, which at times produced a greater undulation in" the limb of Mars, than I ahnoft ever faw. The wind was in the eaft, and probably the columns of warm air blown from London, mixed very irregularly with the atmofphere of Pe- terfham. This ftate of the air, and the low altitude of Mars, whofe fouthern declination was 23**i, rendered it impoflible to diflinguilh with certainty the ftar, from the protuberances in the waving limb of Mars at the moment of immerfion, though the brilliant and filvery light of the ftar contrafted ftrongly with the dull red hue of the planet. The obfervation of the immerfion of the ftar is therefore uncertain, to near a minute 20Q OCCULTATION OF A STAR BY MARSr of time. At the emerfion the ftate of the air was rather more favourable than at the immerfion ; and as the ftar emerged from behind the dark limb of Mars at a fenfible diftance from his enlightened edge, this obfervation is much more certain than ' that of the immerfion ; and is probably true, to five, or ten feconds at mod. EfFcft of the The fiar at its firft emerfion, certainly appeared much fainter ttmofphere of jjj^^ jj jj^j f^^^y afterwards ; but I cannot preteBd to decide, Mars, probably. , , . .... /•.,., that this apparent dimmution ot its light was owmg to any other caufe than its great proximity to the fuperior light of the planet. Yet it was at firfl fo faint as to be very doubtfully viiible, and in lefs than a minute was very confiderably brighter. As in this interval of time, its difiance from the planet was not very much increafed, it is probable that the atmofphere of Mars might have been the caufe, at lead in fome degree, of this appearance. Occultatlon of a Occultation of h f by the Planet Mars, April 17, 1796, ^tXr'' atPeUrJham. Immerfion of b ^ per clock 15'' 4' 48''' Uncertain to nearly one minute. Emerfion of b ^ per clock ..... 15** 24' 28^ Certain to five, or ten feconds at moft. ' The flar pafied to the north of the centre of Mars. The immerfion was about one third, or at moft two fifths of his femidiameler north of the centre. The emerfion uot quit« / half the femidiameter north of the centre, by eftimation. The clock, at the time of the occultation, was faft on mean time 0** 4' 2l|" The immerfion was therefore at . . .13'' 0' 26|'^ The emerfion at . . li** 20' 6f'^ Mean time at Peterfliam. And, Greenwich being 1' 12'' in time eaft of Peterfbam^f the obfervations reduced to tlie meridian of Greenwich are. Mean Time. Apparent Time. Immerfion ... 15'' V 3}^'^ 15^ 2' 28i" Emerfion ... Id'' 21^ 18|" 13" 22' 8|" Although this obfervation is fubje61, from the circumfiances ilaled before, to an uncertainty of half a minute in time, a$ to the middle of the occultation ; yet, as the geocentric mo- tion OCCULTATIOU OF A STAR BY MARS, 20l tion of Mars, was at this time not quite two feconds of a de- Occultation of 1 . 1-1 , I . £• . 1 rt 1 • ^ fixed ftar by gree in three minutes, his place (that or the itar being accu* j j^^ pj^^g^ j^jjj^ rately known)j may certainly be determined by this obferva- tion within a fingle fecond ; with a view, therefore, of afcer- taining the accuracy of the tables of Mars, given in the laft edition of De la Lande*s Aftronomy, the longitude and lati- tude of Mars were computed with care as follow ; 1796, April l?*^ 15** 12' 18''' apparent time at Greenwich. Gcoc. Long. Geoc. . Lat. Auft. Mars 8' 27 "* 7^ 37" 0^ 20' ^l'' 40"' uncorreded, for aberration or parallax. And April, IS** 15^ 12' 18" his place was 8* 27° 23' 2" 0° 22' 53" 18'". His daily motion in longitude^ was therefore 0° 15' 25", and in latitude 0° 2' 16" 38'" increaiing. His aberration in longitude at the time of obfervation, was ~ 3".97, and his horizontal parallax, that of the Sun- being taken at 8''.72, was 11 ".7 12. The parallax iii longitude and latitude, computed by the tables of the Nonagefimal for Greenwich, given in the Con-^ naijfarice des Terns for 1775 is. Par. Long. + 1".772, and Par. JLat. -I- 1 1".2. The apparent place of Mars at the time of the occultatiorv ' was, therefore, by thefe tables, Geoc. Long, Geoc. Lat. Auftt g. 27© 7/ 34/^.8 0° 20' 52''.9. But the place of the ftar, as fettled at Greenwich, was' at the time of occultation. Long. Lat* Auft. 8* 27° 6' 19" 0^ 20' 41" And as the centre of the planet pafled about two fifths of his feraidiameter fouth of the ftar, and the apparent diameter of Liars at that time was very nearly fourteen feconds and an half; the difference of latitude between the ftar and Mars, roay be eftimated at three feconds, without poifible error of above half a fecond. The apparent place then of Mars, as found by obfervation, was, Geoc. Loo^. Geoc. Lat. Auft» 8* 27 *» 6' 19'' 0° 20' 41" ; and the error of the tables is in longitude 4- l' 15". 8, and in latitude + 1 2". Had 202 ' OCCCLTATION OF A STAR BY MARS. Occultat:on of a Had this obfervation been made under favourable circum- sl«etMats. dances, the diameter of Mars mighl probabl)' have been de- duced from it with a great degree of accuracy ; although fuch determination would always have been fubje6l to uncertainty, • from the eftefis of the refraction of his atmofphere, which it is impoffible to eftimate, but which feems, from fome circum- ilances, to be very confiderable. In the prefent obfervation, two other caufes of uncertainty txift. The firft is, the doubt of the duration of the occulta- tion ; the fecond, the poffibility of miftake in the eftimaticn of the difiance of the ftar from the centre of Mars. The firft of thefe caufes cannot induce an error of more than two thirds of a fecond in the eftimate of his diameter. Pro- bably the error is not more than half that quantity. The probable error arifing from the fecond caufe, may amount to about the fame quantity as the former. Of this I formed as near a judgment as I could, by drawing Figure 2, Plate XJI. and placing the path of the ftar at its utmoft limits of diftance from the centre by my eye. If the effecis of both thefe caufes lie the fame way, an error of a fecond and an half in the determination of the diameter of Mars, may pof- fiblyarife; but it is highly probable, that the error is very much lefs than that quantity, putting the etfeds of refraction out of the queftion. Having, therefore, to the bell of my power, compared all the circumftances of the obfervation, and the efiecls oF the above caufes; I confider the equatorial diameler of Mars, as refulling from it, to be at that time 14'^5-: and as the diftance of Mars from the Eartii was llun 0.74456, the Sun*s mean diftance being 1, the diameter of Mars at the mean diftance j of the Sun, would be 10''.8. Dr. Herfchel, in iiis laft paper on Mars, makes it 9''.H. As all the caufes of error in my obfervation, tend rather to dirainifli than increafe the fize of the planet, I am furprifed that I ftiould have exceeded his eftimate ; which is, however, lefs than that of former aftronomers. This, Sir, is all that has occurred to me on the fubjed of this very uncommon obfervation. You will perceive, that I have not, in my eftimations of the diameter of Mars, or of the diftances of the ftar from his limb, made any mention of the fpheroidical figure of the pla« net. Thediifercnces in the refults would be perfeClly infen- fible. IMPROVEMENT IN TIME-PIECES. 203 fible, if that element had been confidered ; and as I never Occultatlon of a ha\'e been able to perceive the difference of his diameters, I n]zntt Mars, -cajinot but fufpecl it to be lefs than Dr. Herfchel fuppofes. I am, Dear Sir, Your obliged and faithful, Maj/23, 1797. H. C. ENGLEFIELD. P. S. In the Connaiffunce des Terns for the jear VI. page 457, and year VII. page 428, are accounts of an obfervation of this occultatlon, made at Aubenas, or Viviers (for it is not certain at which of thefe places) by Mr. Flaugergue, member of the National Inftitute. It is not clear from thefe accounts that he adually faw the emerfion : at 15*58'25^^ apparent time, he faw the ftar^ difiant from the limb of the planet only by an interval equal to the fuppofed breadth of the dark part of the difc of Mars, ahd it was extremely faint, but perfectly white. Its poiilion was about 20® to the weft of the vertical, and above the horizontal diameter. Mr. Flaugergue fuppofes that the ftar paffed within a fecond of the northern limb of Mars, and muft have been hidden ten minutes and an half. , As the place of obfervation was in a lower latitude than Xondon, the obferver there muft have feen the ftar pafs nearer the centre of Mars than I did, the effeCl of parallax being lefs, and the occultation muft in confequence have lafted longer : but my obfervation proves, beyond a doubt, that the ftar paffed much nearer the centre than Mr, Flaugergue fuppofes, as I loft light of the ftar at leaft nineteen minutes and an half. IX. Letter from Mr. Ezekiel Walker, containing a confiderahle Improvement in Time-Pieces by Mr. Barraud, with Rt» marks. To Mr. NICHOLSON, SIR, 1 HE method of determining the longitude by time-keepers. The determlna- poffeffes fome advantages fuperior to any other that has yet *^°" °^ '°"6*'^"''* been propofed. In the firft place, this method is attended is^morTVafytS with ^^^ 1)6 oftener 204 IMPROVEMENT IN TIME-PIECES. made than by with very little trouble ; and, fecondly, the longitude can be other methods, found oftener by a time-keeper than by any other means. I have not met with a more ftriking proof of this pofition, than in the voyage of La Peroufe round the world in the (hip La Remarkable cafe Bouflble. Between the 1ft of Auguft 1785, and the 8th of in proof. September 1787, this celebrated navigator took only 72 lunar obfervations ; but he took 393 obfervations on the longitude by his time-keeper No. 19. This is an unequivocal proof of the benefits that navigation derives from this mode of finding the longitude. But time- keep- It is to be regretted, however, that time-keepers are ex- ers are very ex- pgnftve and liable to ftop, or go irregularly. Were it not for liable to irregu- thefe inconveniences, no other method of finding the longi- ^'^^y* tude need be fought after. But a difcovery was made by Mr. 1 Barraud, about the clofe of the laft century, on the effeds of oil on time-keepers, which not only reduces them in price, but contributes to their performing with greater precifion. Difcovery of Mr. Barraud had frequently communicated to me his im- Mr. ^5^"^^*^^ provements in chronometry, but this difcovery on the effeds keepers areren- of oil, appeared a matter of fo much importance, that I wrote dered more per- ^^ ^^-^^ requefting his leave to publifli it, and the following cheaper. extract is taken from his obliging anlwer. To Mr. WALKER. DEAR SIR, London, Jan, 2^ i 1804-. Letter from Mr. I AM much pleafed to find that it is your intention to favour Banaud. \]^q public with your obfervations on chronometry, and fliall derive fatisfadion in contributing my mite to fo defirable an end : you are therefore welcome to ufe fuch information as my experience of fads enables me to furnifli. Jewelling the The ftate of my regulator I have already defcribed [in a holes of time- f^^mer letter! , from which I infer, that fo far from jewelled keepers IS inju- -• . , , , r i i riousj holes being advantageous in clock-work, they are ablolutely injurious. That they are equally fo in chronometers, I have had abundant experience, having found, almoft without ex- the oil in fuch ception, in chronometers coming oft' a long voyage, the oil in holes bt'ng ^ much worfe condition in the jewelled holes (particularly in than in brafs thofe where the fridion was confiderable) than in the brafs holes. ones. I have therefore been induced, in every inftance, to rejed jewelled holes, and introduce thofe of brafs, and the altcralirii fMPROVEMENT IN TIME-PIECES. 205 alteration has been conftantly favourable to the performance of the tirae-keeper. I flioiild be happy in having a communica- tion with you viva voce on this theme, &c. &c. I am, &c. P. P. BARRAUD. That Mr. Barraud has not made this alteration in his chro- nometers, in a hafty manner, will appear from the following extrad taken from another of his letters. ^ To Mr. WALKER. DEAR SIR, London^ July \1 , 1800. SINCE we parted, I have found additional reafons to believe that jewelled holes (where friclion is great) are in- jurious. A box time-keeper which I have recently taken to Inftance of a pieces, on its return from a long voyage, had the oil in the ^'Tl^'^^JP^""? •'^ brafs holes in a much purer ftate than in the jewelled ones. In was much more the former it ilill remained in a ftate favourable for adion, but/''^*^'^^'^ i^^ the in the latter, the pivots were fo fixed by the tenacity of the the brafs holes : oil, as to require force to extricate them ; the fteel was alfo deeply ftained, and had parted with all its luftre, &c, &c. I am, &c. P. P. BARRAUD. From thefe and many other obfervations made by Mr. Moft probably Barraud upon the effeds of oil on time-keepers, it appears ^j^/a ^^^^'^^ °^ that fmall particles of fteel are worn off by fridion in the jewelled holes, and mixing with the oil, form a glutinous fub- ftance that caufes the time-keeper to go irregularly. On the ASiion of Cold on Oils, IT is a known property of fome oils, that they freeze much Olive oil free«c» fooner than water. The oil of olives freezes at 42^^ ^^ ^^ '^^i ^^^S'"^* Fahrenheit's fcale, confequently the pureft oil of this kind will lofe its fluidity fooner than that which contains fome aqueous particles. Hence we may conclude, that watch- makers ought to make choice of that oil which freezes with the leaft degree of cold ; and as cold has no power to decom- pofe olive oil, it need not be rejected on account of its having aflUmed the concrete form. In 20ff lAW OF GALVANISM IN BURNING THE METALS, In confequence of this oil freezing much fooner than watcr^ the following queries feem to claim our attention ; Hence it may Swery 1. Will a time-keeper go at the fame rate when the ceffarrto\dtuft ^'' '^^ frozen, that it did when the oil was in a fluid ftate ? and keep time- If this query be anfwered in the negative, 2uerj/ 2. Would keepers at tern- jj j^^^ jj^^j^ ^^ improper to adjuft the compenfation balance in pcratures be- * * •' ^ twcen 43' and frofty weather ? i©o'« 2uery 3. Would it not be better to adjuft the compenfation for the efFeds of heat and cold at 43** for the greateft degree of cold, and at 96 or 100** for the other extreme ? A chronometer adjufted in this manner, (hould never be expofed to a greater degree of cold than 43. This may be eafily done with pocket chronometers, but to keep the oil from freezing in box time-keepers, in cold climates, more care may be requifite. Oil has other properties which ought to be carefully examined before it be applied to time-keepers, but this is an inquiry which muft be left until forae future opportunity. I am. Sir, With much refpe6t. Your humble fervant, E. WALKER. X. Letter from C. Wilkinson, Efq. containing FaBs upon which Dedudtions are made to Jhexv the Law of Galvanifm in burn" ing the Metals, according to the Dijpofition of equal Surfaces qf charged Metallic Plate, To Mr. NICHOLSON, SIR, AF the following obfervations fiiould be deemed worthy of infertion in your valuable Journal, I fliall take the liberty of troubling you with fome further remarks hereafter. I am. Sir, Yours refpedfuHy, Soho Square, C, WILKINSON. 5 When tAW OP GALVANISM IN BURNING THE METALS. ^Qjff When the French philofophers had afcertained that a feries Introduftion-, of galvanic plates produced etledls on animal fubftances in pro- portion to the number oF plates employed, without any regard to the furface of each plate, they concluded from their ex- periments, that the eifeds of a galvanic battery on metallic liibflances are in proportion to the furfaces of the plates em- ployed. I have lately been engaged in experimeiits with thq moftextenfive galvanic apparatus hitherto conftru6led, from which fome circumftances have occurred, in fome refpeds 'militating with the dedudions of the French philofophers. A galvanic trough containing one hundred fquare plates ofOnehunditJ four inches in the fide, each plate formed of a plate of zinc sa^vauic phte» * . , r , . of four incae» and copper foldered together; when charged with a folution or fquare burned nitrous acid 'and water in the proportion of about 25 parts half an inch o€ water to one of acid, exhibited a power capable of igniting half an inch of fleel wire of about one feventieth of an inch in diameter. When two fuch troughs were combined endwife, the power Other trough* was doubled, and when four were thus arranged, the quantity burned mw? of wire ignited was quadrupled : hence I afcertained in a very v/ire inpropor- extenfive arrangement, that the power is invariably in propor- 5 °"of '?^t""°*" tion to the number of plates employed. A galvanic trough confiding of fifty fquare plates of eight A trough of inches each in the fide was charged with a fimilar prepared fo- ^^^^l P'^'^'^* ^ * r r . much more lutlon, and this arrangement I found capable of igniting fix- power, teen inches of the fame wire as was employed in the former experiment. When two, three, and four troughs of the fame fize were —which in- eombined, the lengths of wire ignited proved to be in propor- cjeafed propor- tion to the number of plates employed; fo that two hundred number, eight inch plates ignited more than five feet of wire. Thefe experiments prove that the powers increafe in a Examination of greater ratio than as the furfaces of the plates employed. For ^^ J.^^"^'**^ four hundred plates of four inches, containan equal furface with power of largt^ one hundred plates of eight inches; and the former will only P'^*^"' ignite two inches of the fame wire, of which the latter will ignite thirty-two inches. If this proportion fliould be obferved in experiments with ^y ^V^^^ ^o^l plates of different fize, it will appear that the powers of ig- bu^rned's ts £* niting, as meafured by the length of wire, increafe, in batteries fquare of tha of the fame total furface, as the fquares of the furfaces of thet'''^^"^^''y ^•'" Elementary plates, lingly taken in each, A plate. ^)$ LAW OF GALVANISM IN BURNING THE METAL*. Reafonlngon A plate of eight inches diameter expofes a furface four times h^ ^'^ll* e greater than a plate of four inches, and fuppoling the quanti- throw our dec- ties of electricity given out, to be in proportion to the furface tncity move expofed to the chemical a6lion of the fluid'^, the intenfity of (or rapidly. , . ... rapidity of evolution from) ea" "^X ^^^ ^^P^^ ^n this fubjeft,* I have divided the va- heavenly bodies, rious objeds whicli aftronomy has hitherto brought to our view. Into twelve clalFes. The firft comprehends infulated ftars. As the folar fyftem prefents us with all the particulars that piay be known, refpe6ting the arrangement of the various fu- bordinate celeftial bodies that are under the influence of ftars which I have called infulated, fuch as planets and fatellites, • afteroids and comets, I fliall here fay but little on that fubjed. It will, however, not be amifs to remark, that the late addition of two new celeftial bodies, has undoubtedly enlarged our know- ledge of the conftruftion of the fyftem of infulated ftars. Whatever may be the nature of thefe two new bodies, we know that they move in regular elliptical orbits round the fun. It is not in the leaft material whether we call them afteroids, as I have propofed ; or planetoids, as an eminent aftronomer, in a letter to me, fuggefted ; or whether we admit them at once into , the clafs of our old feven large planets. In the latter cafe, how- ever, we muft recoiled, that if we would fpeak with precilion, they (hould be called very fmall, and exzodical ; for, the great inclination of the orbit of one of them to the ecliptic, amounting to 35 degrees, is Certainly remarkable. That of the other is alfo confiderable ; its latitude, the laft time I faw it, being more , than 15 degrees north. Thefe circumftances, added to their fmallnefs, fliow that there exifts a greater variety of arrange- ment and fize among the bodies which our fun holds in fubor-» dination, than we had formerly been acquainted with, and ex- tend our knowledge of the conftrudion of the folar, or infulated fidereal fyftem. It will not be required that I fliould add any * See Phil. Tranf. for 1802, p. 477, and oar Journal, V. 72, thing POSfTION OF irOUBtE STARS. ' Git thing farther on the fabje6t of this firft article of my claffifi- General obfer- cation ; I may therefore immediately go to the fecond, which 7^^"' °"t^g* treats of binary fidereal fyftems, or real double ftars. heavenly bodies. We have already (hewn the poffibility that two ftars, what- foever be their relative magnitudes, may revolve, either in circles or ellipfes, round their common centre of gravity; and that, among the multitude of the ftars of the heavens, there ihould be many fufficiently near each other to occafion this mutual revolution, muft alfo appear highly probable. But neither of thefe confi derations can be admitted in proof of the aftual ex- iftence of fuch binary combinations. I (hall therefore now proceed to give an account of a feries of obfervatipns on double ftars, comprehending a period of about 25 years, which, if I am not miftaken, will go to prove, that many of them are not merely double in appearance, but muft be allowed to be real binary combinations of two ftars, intimately held together by the bond of mutual attradion. It will be neceflary to enter into a certain theory, by which thefe obfervations ought to be examined, that we may find to what caufe we ftiould attribute fuch changes in the pofition, or diftance, of double ftars, as will be reported; and, in order to make the required principles very clear, I ftiall give them in a few (hort and numbered fentences, that they may be referred to hereafter. In Plate. X. Fig 1. let us call the place of the fun, which Theory of ths may alfo be taken for that of the obferver, O. In the centre of "^^^^""^ °^ '^ an orbit or plane N F S P is a Geminorum ; and, if any other ftar is to be examined, we have only to exchange the letter a for that by which fuch double ftar is known. This letter is always underftood to reprefent the largeft of the two ftars which make up the double ftar; and a general expreflion for its fmaller companion will be x. N, F, S, P, reprefent the pofitions of the different parts of the heavens, with refpe6l to a, north, fol- lowing, fouth, and preceding ; and the fmall: letters n, /, s, p, ftand for the fame dire6lions with refpedl to O. xaP, is the angle of pofition of the two ftars x and a, with the parallel F P. As the motion of an obferver a fre6ls the relative filuation of objeds, we have three bodies to confider, in our inveftigatlon of the caufe of the changes which will be pointed out; the fun, the large ftar, and the fmall ftar, or, as we have ftiortly called f2 them. Theory of the motions of the ftars. CAUS& or tHE CHAHOES OV RELATIVE them, O, », X. This admits of three cafes : a motion of one o? the three bodies ; another, of two ; and a third, of all the three bodies together. We (hall now point out the confequences that will arife in each of the cafes. Single Motions. No. 1. Motion of x. When a and O are at reft, the motion of j: may be alTumed, fo as perfedlly to explain any change of the diftance of the two ftars, and of their angle of pofition. No. 2. Motion of a. When x and O are at reft, and a has a motion, either to^wards P, N, F, or S, then the effed of it, whatever may be the angle P a O, will be had by entering the following Table, with the dire6tion of the given motion. Motion. Diftance. Angle. Quadrants. -f 1ft and 4th 2 3 a? + aF + + 1 4 2 3 aN + -f 1 2 3 4 aS -f + 1 2 3 4 No. 3. Motion of O. 1 ft cafe. When a. and x are at reft, and the angle P a O is 90 degrees, a proper motion of O, towards either j!7,/, w, or «, which will be extremely fmdll when com- pared with the diftance of O from », can have no effed on tiie apparent diftance, or angle of pofition, of the two ftars ; and therefore no other motion, compofed of the diredions we have mentioned, will induce a change in the comparative fituation of a and X, 2d cafe. When the plane P N F S is oblique to the ray « O, and the angle P o^ O more tlian 90 degrees, the efl^eft of th^ motion of O will be had by the following Table. Motion POSITION or DOUBLE STAKS, Motion. Diftance. 1 Angle. Quadrants. Op + — I ft and 2d 3 4 Of — + ] 2 3 4 On + + 1 3 2 4 Os + + 2 4 213 Theory of the motions of the ftar*. 3d cafe. When the angle P a O is lefs than 90 degrees, the following Table muft be ufed. i Motion. Diftance. Angle. Quadrants. Op + 1ft and 2d 3 4 Of + — I 2 3 4 On + + 1 3 2 4 o. + + 1 3 2 4 ■ ^ Double Motions. No. 4. If we admit different motions in two of our three )dies!, and if the ratio of the velocities, the dire6tions of the lotions, and the ratio of the diftances of the bodies be given quantities, a fu]ppo(ition in which we admit their concurrence, may explain tlie phenomena of a double ftar, but can never be probable - Motions of the three Bodies. No. 5. If we admit different motions in every one of the three bodies, O «,, x, and if the velocities and directions of the motions^ 214 ^AUSE OF. THE CHANGES OF RELATIVE Theery of the motions, as well as the relative diftances of the three bodies are ftws^^ " * determined, an hypothefis which admits the exiftence of fuch motions and fituations, may refolve the phenomena of a double flar, but cannot have any pretenfion to probability. The compafs of this Paper will not allow me to give the ob- fervations of my double ftars at full length ; I fhall therefore, in the examination of every one of them, only ftate thofe parti- culars which will be required for the purpofe of inveftigating .the caufe of the changes that have taken place, either in the diflance, or angle of pofition, of the two flars of which thd double flar iscompofed. As the arguments in the cafe of moft of thefe flars will be nearly the fame, it may be expelled, that the firft two or three which are to be examined will take up a confiderable fpace, and the number of doable ftars, in which I have already afcer- tained a change, amounting (o more than fifty, it will not be poffible to give thera all in one paper ; I ftiali therefore confine the prefent one to a moderate length, and leave it open for a continuation at a future opportunity. a Geminorunu Obfervatlonsand From my earlieft obfervations on the diflance of the two flars inferences re- which make up the double flar in the head of Caftor, given in ch^angef of re- *-^® ^^^ ^^ ^y catalogues of double flars, we find, that about 23 lative fituation years and a half ago, they were nearly two diameters of the iyneareacT°'"^^!:se ^ar afunder. Thefe obfervations have been regularly •ther. continued, from the year 1778 to the prefent time, and no al- teration in the diflance has been perceived : the flars are now flill nearly two diameters of the large one afunder. It will be neceflary to enter a little into the pra6licability of afcertaining diftances by a method of eflimation apparently fo little capable of precifion. From a number of obfervations and Experiments I have made on the fubjefl, it is certain that the apparent diameter of a flar, in a refle6ling telefcope, depends chiefly upon the four following circumflances : the aperture of the mirror with refpeft to its focal length ; the difiin61nefs of the mirror; the magnifying power ; and the flate of the almofpher* at the time ®f obfervation. By a contraction of the aperture we can increafe the apparent diameter of a flar,, fo as to maki it refemble a fmall planetary difk. If diflindnefs ftiould wanting, it is evident that the image of objeCls will not be ftiai an( other. rOSlTION OP DOUBLE STARS. ' 2l5 and well defined, and that they will confequently appear larger Obfervationsand than they ought. The effect of magnifying power is, to occafion fpe^ing the a relative increafe of the vacancy between two liars that are changes of re- very near each other ; but the ratio of the increafe of the dif- j^ ftars «trcme- tance is not proportional to that of the power, and fooner or ly near each later comes to a maximum. The flate of the atmofphere is per-* haps the raoft material of the four conditions, as we have it not in our power to alter it. The effeds of moifture, damp air, and hazinefs, (which have been related in a paper where the caufes . that often prevent the proper adion of mirrors were dif- cuffed,) (how the reafon why the apparent diftanceof a double ilar fhould be affedled by a change in the atmofphere. The alteration in the diameter of Ardurus, extending from the firft to the laft of the ten images of that ftar, in the plate accompany- ing the above-mentioned paper,* (hows a fufficient caufe for an increafe of- the diftance of two flars, by a contraction of their apparent difks. A (kilful obferver, however, will foon know what ftate of the air is mod: proper for eftimations of thi;; kind. I have occafionally feen the two flars of Caftor, from l{ to 2 and 2| diameters afunder ; but, in a regular fettled temperature and clear air, their diftance was always the fame. The other three caufes which affe6lthefe eftimations, are at our own dif- pofal ; an inftance of this will be feen in the following trial. I took ten different mirrors cf feven feet focal length, each hav- ing an aperture of 6,3 inches, and being charged with an eye- glafs which gave the telefcope a magnifying power of 460. With thefe mirrors, one after another, the fame evening I viewed the two ftars of our double fiar; and the refult was, that with every one of them, the ftars were precifely at an equal diftance from each other. Thefe mirrors were all fufficiently good to ftiow minute double ftars well; and fuch a trial will confequently furnilh us with a proper criterion, by which we may afcertain the goodnefs of our telefcope, and the clearnefs • of the atmofphere required for thefe obfervations. To thofe • who have not been long in the habit of obferving double ftars, it will be neceffary to mention, that, when firft feen, they will appear nearer together than after a certain time; nor is it fo foon as might be expeded, that we fee them at their greateft * Sec Phil. Tranf. for 1803, page 232, Plate III. diftance. Q\Q tAVSE OF THE CHANGES OF RLLATlVK Cibfervationsanddiftance, I have known it to take up two or three nlonthsTy fpeSrthr' ^^^^^^ ^'^6 ^ye vvas fafficiently acquainted with the objea, to changes of re- judge with the requifite precifion. lative fituation ' Whatever may be the difficulties or uncertainties, attending mftars extreme- ti,-! •• t n r ^ r n i ly near each the method of determining the diftance of two dole ftars by other. an eftiraation of the apparent diameter, it mufi: however be con- fefled, that we have no other way of obtaining the fame end w^ith fo much precilion. Our prefent inftance of a Geminorum, will ftiow the degree of accuracy of which fuch eftimations.are capable, and at the fame time prove^ that the purpofe for which I (hall ufe the eftimated interval between the two ftars will be fufficiently anfwered. By an obfervation of the 10th of May, 1781, we have the diameter of the largefl; of the two ftars to that of the fmalleft as 6 to 5 ; and according to feveral n:>ea- fures I have taken with the micrometer, we may admit their diftance, diameters included, to be five feconds. Then, as the vacancy between the two ftars is nearly, but not quite two dia- meters of the large one, I ftiall value it at 1|-. From this we calculate, that the diameter of the large ftar, under the circum- llances of our eftimation, is nearly V',S5 : fo that an error of one, quarter of fuch a diameter, which is the moft we can admit, .will not exceed 0",34'. Nor is it of much confequence, if the meafure of 5^' ftiould not be extremely corred; as a fmall miftake in that quantity will not materially affe<5t the error of eftimation by the diameter, which, from what has been faid, if the meafure was faulty to a fecond, would not amount to more than one-fifteenth part of it. Having thus afcertained that no perceptible change in the diftance of the ftars has taken place, we are now to examine the angle of pofition. In the year 1779, it was 32° 47' north preceding; and, by a mean of the three laft meafures I have taken, it is now only 10° 3S'. In the fpace of about 23 years and a half, therefore, the angle of pofition has manifeftly under- gone a diminution, of nolefs than 21^ 54'; and, that this change ha- been brought on by a regular and gradual decreafe of the angle, will be feen when the reft of the meafures come to be examined. The accuracy of the micrometer which has been ufed, when the angles of pofition were taken, being of the utmoft im- portance, it becomes neceflary to afcertain how far it will be fafe to rely on the refult of the meafures. It might be eafily fliown POSITION OF DOUBLE STjWRS. 5^17 ftinwn that, in the day time, a given angle, delineated^ on a card, Obfervationsand J n. 1 , ■ ,■ n 1 r II 1 inferences re- ann Ituck up at a convenient diltance, may be tu!l as accurately fpefting the mealured by a telefcope furnilhed with this niicromeler, as it changes of re- can be done by any known method, when the card is laid on a jnft^rs ext^reme* table before us ; but this would not anfwer my purpofe. For, ly near each objeds in motion, like the ftars, efpecially when at a diftance °'^®^* from the pole, cannot be meafured with fuch fteadinefs as thofe which are near us, and at reft. The method of illuminating the wires, and other circumftances, will likewife afFe6l the accuracy of the angles that are meafured, efpecially when the diftance of the ftars is very fmall. I fliall therefore have re- courfe to aftionomical obfervations, in order to f«e what the micrometer has adually done. January 22, 1802. The pofition of A Orionis was taken. 1ft meafure, 52^ 38' fouth preceding; 2d meafure, 54^ 14'. Mean of the two meafures, 53° 26'. Deviation of the mea- fures from the mean, 48'. ^ March4, 1S02. II Monocerotis. 1 ft meafure, 28 « 18' fouth following; 2d meafure, 26^ 49'. Mean of the two, 27° 34'. Deviation from the mean, 45'. February 9, 1803. a Geminorum. ift meafure, 6** 11' north preceding; ,2d meafure, 4° 48'. Mean of the two, 5° 29'. Deviation from the mean, 41'. September 6, 1802. n Coronae. ift meafure, 89^ 42' north following ; 2d meafure, 89° 38'. Mean of the two, "89° 40'. Deviation from the mean, 2'. When thefe obfervations are confidered, we ftiall not err much if we admit that, in favourable circumftances, and with proper care, the micrometer, by a mean of two meafures, will give the pofition of a double ftar true to nearly one degree; but, as the opportunities of taking very accurate meafures are fcarce, it will be neceflary to have recourfe to forae more dif- cordant obfervations. February 18, 1803. ^ Orionis. ift meafure, 72° 58' fouth preceding; 2d meafure, 67*24'. Mean of the two, 70° 11'. Deviation from the mean, 2^ 47'. But a memorandum to the obfervation fays, that the even- ing was not favourable. We may therefore admit, that in the worft circumftances which can be judged proper for meafur- ing at all, an error in the angle of pofition by two meafures will not amount to three degrees. It 2lg CAUSE d% THE CHANGES OF RBtATIVE Obfcryations n will be remarked, when we come to compare fingM and inferences ^ i • i i i , ,.^ .... refpefting the "^calures which have been taken on diJfTerent nights, that they changes of re- are fomewhat more difcordant ; but I have not ventured to ftrrrextr"emery ^^i^^ t^^m on that account, except in cafes where it was near each other* pretty evident that fome miftake in reading off, or other ac- cident to which all aftronomical obfervations are liable, was to be apprehended. Nor can fuch difagreements materially afFe€t the conclufions I have drawn, when it appears that the deviations happen Ibmetiraes to be on one fide, and fometimes on the other fide, of the true angle of pofition. For, fince that angle is not a thing that will change in the courfe of a few nights, the excefs of one meafure will ferve to correal the defed of another; and we are not to think it extraordinary, when flars are fo near together, and their motion through the field of view (in confequence of the high magnifying power ^e are obliged to ufe) fo quick, that we (hould now and then even fall fliort of that general accuracy which may be had by a careful ufe of the micrometer. I ftiall now enter into an examination of the caufe of the change in the angle of pofition of the fmall ftar near Caftor. A revolving ftar, it is evident, would explain in a moll fatisfadlory manner, a continual change in the angle of pofition, without an alteration of the diftance. But this, being a cir- cumftance of which we have no precedent, ought not to be admitted without the fulieft evidence. It will therefore be right to examine, whether the related phenomena cannot be fatisfadtorily explained by the proper motions of the ftars, or of the fun. Single Motions, ' (a) The three bodies we have to confider, are O, a, andx; and, fuppofing them to be placed as they were obferved to be in the year 1779; the angle x a>?, in Fig. 1, will be 32'^ 47' north preceding. We are at liberty to let the angle PaO be what will beft anfwer the purpofe. Then, in order to examine the various hypothefes that may be formed, according to the arrangement of the principles we have given, we ftiall begin with No. 1 ; and, as this admits that all phenomena may be refolved by a proper motion of x, let us fuppofe thisfiar to be placed any wliere far beyond a, but fo as to have been feen, in the year 1779, wheie the angle of pofition, ti2^ 47' north pre- ceding POSITION OP DOUBLE STAllSr f219 tsedlng, and the obferved diftance, near 2 diameters of the large Obfervatiom flar, required it. With a proper velocity, let it be in motion refpedUngllMt* towards the place where it may now be feen at the fame d if- changes of re- tance from Caftor, but under an angle of pofition only 10^ 53' |n ft^rf «trem«- north preceding. It may then be admitted, that a fmall decreafe ly near each of the diftance which would happen at the time when the angle °*^'* of pofition was 21^ 50', could not, have been pej;ceived; fo that the gradual change in the obferved angle of pofition, as well as the equality of the diflance of the two flars, will be fufhciently accounted for. But the admiffion of this hypothefis requires, that a Geminorum and the folar fyflem fhould be at refl; and, by the obfervations of aflronomers, which I fhall foon have occafion to mention, neither of thefe conditions can be con- ceded. {b) If, according to No. 2, we admit the motion of a, wq fliall certainly be more confifient with the obfervations which iflronomers have made on the proper motion of this fiar * ; and, . » &s a motion of the folar fyfiem, which I fhall have occafion to mention hereafter, has not been rigidly proved, it may, for tha fake of argument, be fet alide ; nor has a proper motion of the ilar X been any where afcertained. The retrograde annual proper motion of Cafior, in right afcenfion, according to Dr. Mafkelyne, is 0'',103. This, in about 23| years, during which time I have taken notice of the angle of pofition and diftance of the fmall fiar, will amount to a change of nearly 2'',47, ' Then, if we enter the fhort Table I have given in No. 2, with the motion aP, we find, that in the firfl quadrant, where the fmall flar is placed, the diftance between the two flars will be diminillied, and the angle of pofition increafed. But fince it appears, by my obfervations, that the difiance of the frars is not lefs now than it was in 1780; and that, infiead of an in- creafe in the angle of pofition, it has actually undergone a diminution of nearly 22 degrees; it follows, that the motion n of a Geminorum in right afcenfion, will not explain the obferved alterations in the fituation of this double flar, li^ * See Tobije Mayeri Opera inedita. De motu jixarum propria, page 80. Alfo Dr. Maskelyne's firfl Volume of Obfervations. Ex- planation and \5iQ of the Tables, p. iv. Or Mr. Wollafton's Ai- tronomical Catalogue, end of the Preface. Likewife Connoiffance des ^empspQur l" Annie VI. p. 203. Sur le Mowvement particulier pro* pre a differentes Etoilesj par Mons, De la Lande, according. other. q<20 CAirSfi 6F THE CHANGE Of RELAYlVE ObiVrvatlons according to Mr. De la Lande's account*, we fliould alftf and intcrctces /- , , , . ,,.,,.. , . . re(pc ajng he confider the annua! proper motion or » m decimation, which changes otte- \g gjveii 0'',]2 towards the north, we lliall find, by entering lative fituation rr-. i i • ■ • .• Tk.T . ^'/„^ .i ^ xl^ in ftars extreme- ^""^ Table with the motion «tN, amountmg to 2 82, that the !y near each. diftance oF the two ftars will bo ftill more' diminifhed ; but that, on the contrary, the angle of pofition will be much lelfened ; and, by combining the two motions together, the apparent difks of the two flars fliould now be a little more than one-tenth of a fecond from each other, and the angle of pofition 35 degrees fouth preceding. But, fince neither -of thefe effects have taken place, the hypothefis cannot be ad- mitted. (c) That the fun has a proper motion in fpace, I have fliown / with a very high degree of evidence, in a paper which was read at the Royal Society about twenty years ^go f . The fame opinion was before, but only from theoretical principles, hinted at by Mr. De la Lande, and alfo by the late Dr. Wilfon, of Glafgow + ; and has, fince the publication of ray paper, been taken up by feveral afironomers^, who agree that fuch motion exifts. In confequence of this, let us now, according ia No. 3. affign to the fun a motion in fpace, of a certain velocity and dire6tion. Admitting therefore a, and x to be at teft, let the angle PaO be 90 degrees; then, by ihe ift cafe ot No. 3, we find that none of the obferved changes of the angles of pofition will admit of an explanation. There is moreover an evident conceiTion of the point in queftion, in the very fuppofition of the above angle of 90 degrees ; lor, if a? be at the fame diftance as a from the fun, and no more than 5'' from that ftar, its real diftance, compared to that of the fun from the ftar, will be known; and, fince that muft be lefs than the 40 thoufandth part of our diftance from Caftor, thefe two ftars muft neceflarily be within the reach of each others altradion, and form a binary fyftem. (d) Let us now take the advantage held out by the 2d cafe of No. 3, which allows us to place x far behind a ; in which * See page 21 1 of the treatife before referred to. t Philof. Tranf. vol. Ixxiii. p. 247. J See my note in Phil. Tranf. vol. Ixxiiii p. 283. § See jiJJronomiJhes Jahrhuch fur das Jahr 1786; feite 259. Ubir die fortruckung unferes Sonnen-Syjiems, von Herrn Fffejfor Prcvoft. IJnd fur das Jahr 1 ^0^, feite 113, fituation JPOSITION 0F DONBLE STARS. 221 fituatlon, the angle PaO will be more than 90 degrees. The Obfervations ** , r- 1 ^"'^ inferences Itar X being lets than a, renders this hypolhefis the more refpeaing the plAufible. Now, as a motion of Caftor, be it real or apparent, changes of re- has adlually been afcertained, we cannot fet it alide ; the real j„ ^^^^^ extreme^ motion of O, therefore, in order to account for the apparent one ly near eachi of a, muft be of equal velocity, and in a contrary direction :° "* that is, when decompofed, (y',l05 towards/, and (^\\2, to- wards s. The effedl of the fun's moving from O towards/, according to the 1ft Table in No. 3, is, that the diflance be- tween the two liars will be diminifhed, and the angle of pofi- tion increafed. But thefe are both contrary to the obferva- tions I have given. The motion of O in declination towards *, according to the fame Table, will ftill diminifh the diftance of the two liars, but will alfo dirainifli the angle of pofition. Then, lince a motion in right afcenfion increafes the angle, while that in decimation diminiflies it, the fraall ftar may be placed at fuch a dillance that the difTerence in the parallax, arifing firom the folar mbtion, fhall bring the angle of pofition, in 23f years, from 32^ 47' to 10" 53' ; which will explain the obferved charige of that angle. The di fiance of the dar x, for this purpofe, muft be above 2| times as much as that of a from us. But, after having in this manner accounted for the alteration of the angle of pofition, we are, in the next place, to examine the effe6l which fuch a difference of parallax muft produce in the apparent diftance of the two ftars from each other. By a graphical method, which is quite fufficient for our purpofe, it appears, that the union of the two motions in right afcenfion and declination, muft have brought the two ftars fo near, as to be only about half a diameter of the large ftar from each other ; or^ to exprefs the fame in mea- furesi the centers of the fiars muft now be V',S nearer than they were 23| years ago. But this my obfervations cannot allow ; for we have already fhown, that any change of more than 3 or 4-tenths of a fecond muft have been perceived. If, on the other hand, we place the ftar x at fuch a diftance that the folar parallax may only bring it about 4-tenths of a fecond nearer to a, which is a quantity we may fuppofe to have efcaped our notice in eftiraating the apparent diftance of the two ftars, then will the angle of pofition be above 20 degrees too large. This fhows, that no diftance, beyond Caftor, at which we can place the ftar, will explain the given obferva- tions, • ^ Jf22 CAUSE »F THE CHANGES OP RELATITB Obfervationi C^) The laft rernaining trial we have to examine, is to fupi TtfptklnTthl P°^®'^ ^^ be nearer than »; the angle P aO, will then be lefa changes of rela- than 90 degrees ; and the effe6l of a motion of O towards/, ftlr^ «Trerely'" ^^ ^^^ ^"^ ^^^^^ '" ^°' ^* "^'^^ ^^ ^" increafe of the diftanc« ■ear each other, o^ ^he two ftars, and a diminution of their angle of pofition. But tiie motion O^, which is alfo to be confidered, will add to the fncreafe of the diftance and counteract the diminution of the angle. It is therefore to be examined, whether fuch an increafe of .diftance as we can allow to have efcaped obferva- tion, will explain the change which we know to have hap- pened in the angle, during the laft 23 1 year. By the fame method of compounding the two motions as before, it imme- diately appears, than we cannot place the fmall ftar more than about 1 -tenth of the diftance Oa on the fide of Caftor, with^ out occafioning fuch an increafe of the apparent diftance of the two ftars as cannot poffibly be admitted ; and that, even then, the angle of pofition, inftead of being lefs, will be a few degrees larger, at the end of 23f years, than it was at the beginning. This hypothefis, therefore, like all the fore- going ones, muft alfo be given up, as inconfiftent with my obfervations. It is moreover evident, that the obfervations of aftronomers on the proper motion of the ftars in general, will not permit us to aflume the folar motion at pleafure, merely for the fake of accounting for the changes which have happened in the ap- pearances of a double ftar. The proper motion of Caftor, therefore, cannot be intirely afcribed to a contrary motion of the fun. For we can affign no reafon why the proper motion of this ftar alone, in preference, for inftance, to that of Arc- turus, of Sirius, and of many others, Iliould be fuppofed to arife from a motion of the folar fyftem. Now, if they are all equally intitled to partake of this motion, we can only admit it in fuch a direction, and of fuch a velocity, as will fatisfy mean direction and velocity of the general proper motions of the ftars ; and place all deviations to the account of a real proper motion in each ftar feparately. Double Motion, (/) In order to explain the phenomena of our double ftar, according to No. 4, by the motion of two bodies, for inftancft « and Xf it will be required that they both (hould move in given 4 diredions^j POSITION OF DOUBLE STARS. 22^ direQions ; that the velocities of their motions fliould be in a Obfervations given ratio to each other ; and that this ratio fliould be com- ^"^ *"^f ^^°*i^' pounded with the ratio of their diftances from O ; a fuppofi- changes of rela- tion which muft certainly be highly improbable. To ftiew this tive fituation ia with fufficient evidence, let us admit that, according to the j^^^^ each othcrji beft authorities, the annual proper motion of Caftor is — 0'^ 105 in right afcenfion, and 0'',12 in declination towards the north. Then, as the fmall ftar, without changing its diftance, has moved through an angle of 2 1'* 54', the only difference in the two motions of thefe ftars, will be exprefled by the extent of the chord of that angle. To produce the required effeft, it is therefore neceffary that the motion of a, which is given, fliould regulate that of the fmall ftar, whofe relative place at the end of 23^ years is alfo given. Then, as a moves in an^ gle of 53'' 31' north preceding, and with a velocity which, being exprefled by the fpace it would defcribe in 23f years, will be 3''',51, it ijf required that x (hall move in an angle of 29 '^ 25', like wife north preceding, and with a velocity of 3''',02. The ratio of the velocities, therefore, and the direc- tions of the motions, are equally given. But this will not be fufficient for the purpofe : their diflance from O muft alfo be , taken into conlideration. It has been fhown, that the two ftars cannot be at an equal diftance from us, without an evi- dent connexion ; it will therefore be necefTary for thofe who will not allow this connexion, to place one of them nearer to us than the other. But, as the motions which have been af- fumed, when feen from different diftances, will fubtend lines whofe apparent magnitudes will be in the inverfe ratio of the affumed diftances, it is evident that this ratio, if the motions are given, muft alfo be a given one ; or that, if the diftances be affumed, the ratio of the motions muft be compounded with the ratio of the diftances. How then can it be expected that fuch precife conditions fliould be made good, by a concurrence of circumftances owing to mere chance ? Indeed, if we were inclined to pafs by the difficulties we have conjfidered, there is ftill a point left which cannot be fet aflde. The motion of the folar fyftem, although its precife direction and velocity may ftill be unknown, can hardly admit of a doubt ; we have therefore a third motion to add to the former two, which con- fequently will bring the cafe under the ftatement contained in our 7th number, and will be coniidered hereafter. jB24 CAUSE OF THE CHANGES OF RELATIVE Obfervatlons (g) If we ftiould intend to change our ground, and place and inferences the two motions in O and Xt it will then be conceded, that the changes of rela- "^°^'^" ^^ ^ '^ °"b' ^" apparent one, which owes its exigence tive fituations into the real motion of the fun. By this, the effed of the folar ^''a'r wcTothL. parallax on any ftar at the fame diftance will be given ; and it cannot be difficult to aflume a motion in x, which fliall, with the effefl of this given parallax, produce the apparent motion, in the direction of a chord from the firft to the laft angle of pofition pointed out by my obfervations; taking care, however, not to place the ftars a and x at the fame diftance from us ; ufing the inverfe ratio of the folar parallax as a multiple in the affigned motion. For inftance, let the fun have a motion of the velocity exprefled as before by S'\5l, and in a dire6lion which makes an angle of 53^^ 13' fouth following with the parallel of a Geminorum ; and let the fmall flar x have a real motion in an angle of 18*^ 40' fouth preceding from the pa- rallel of its filuation, and with a real velocity which, were it at the diftance of a, would carry it through 8^^89. Then, if the diftance of the fmall ftar be to that of the large one as 3 to 2, the effefl of the folar parallax upon it will be y of its eff*e6t upon a ; that is, while a, which is at reft, appears to move over a fpace of 3'',5I, in an angle of 53^ 31' north pre- ceding, the paralla6tic change of place in x will be 2", 3 4 in the fame dire6lion. This, though only an apparent motion, will be compounded with the real motion we have afligned to it, but which, at the diftance of », will only appear as l" ,26 ; and the joint effedl of both will bring the ftar from the place in which it was feen 23 1 years ago, to that where now we find it fituated. a, in the fame time, will appear to have had an annual proper motion of — 0"A05 in right afcenfion, and (y',12 in declination towards the north ; and thus all pheno- mena will be explained. From this ftateraent, we may draw a confequence of con- ftderable importance. If we fucceed, in this manner, in accounting for the changes obferved in the relative fituation of the two ftars of a double ftar, we ftiall fail in proving them to form a binary fyftem ; but, in lieu of it, we ftiall gain two other points, of equal value to aftronomers. For, as a Ge- minorum, according to the foregoing hypothefis, is a ftar that has no real motion, its apparent motion will give us the velo- city and direction of the motion of the folar fyftem ; and, this being $ POSITION OF DOUBLE STARS. ^^^ being obtained, we (hall alfo have the relative parallax ofobfervations every ftar, not having a proper motion, which is affeded by ^"^ inferences the folar motion. Aftronomical obfervations oh the proper changes of rela- motion of many different ftars, however, will not allow us t©''ve fituation in- account for the motion of a Geminorum in the manner ^^'^^^ nt&t llch^iJx* the foregoing inftance requires ; the hypothefis, therefore, of its being at reft, muft be rejeded. (/i) If we place our two motions in O and a, we ftiall be led to the fame conclufion as in the laft hypothefis. The known , proper motion of a, and the fituations of the fmall ftar in 1779 and 1803, given by my obfervations, will afcertain the apparent motion of x, now -fuppofed to be at reft. Then, fince the change in the place of x muft be intirely owing to the effed of parallax, it will confequently give us, in the fame manner as before, the quantity and diredtion of the motion of the folar fyftem, and the relative diftances of all fuch ftara as are affedled by it. But, here again, the folar motion re- quired for the purpofe is fuch as cannot be admitted ; and the hypothefis is not Maintainable. Motion of the three Bodies, (i) There Is now but one cafe more to conftder, which is, according to No. 5, to alTign real motions to all our three bodies ; and this may be done as follows. Suppofe the fun to move towards X Herculis, with the annual velocity 1. Let the apparent motion of a, Geminorum be as it is ftated in the aftronomical tables before mentioned; butfuppofe it to arife from a compofition of its real motion with the effed of the fyftematical parallax, as we may call that apparent change of place of ftars which is owing to the motion of the folar fyftem. Let the real motion of x, aided by the effect of the fame pa- rallax, be the caule of the changes in the angle of pofition which my obfervations have given. We may admit the largeft of the two ftars of our double ftar to be of the fecond magni- tude ; and, as we are not to place x too near a, we may fup- pofe its diftance from O to be to that of « from the fame as 3 to 2. In this cafe, O will move from the parallel of an in an angle of 60® 31^ north following, with an apparent annual velocity of ,4536. The motion of a in right afcenfion, may be intirely afcribed to folar parallax; but its change of declination, can- not be accounted for in the fame manner. Let us therefore ^ Vol. VII.— March, 1804.. Q admit 'g^C CAUSES or THE CHANG5S OF RELATIVE ©bfcrvations admit that the folar velocity, in the direction we have caTctr- jr/eahT'th" ^^^^^' ^'^' produce an apparent retrogate motion in a, which, changes of rela- i" '^^l vcars will amount to 2",085 in right afcenfion. But the tive fituations in fame parallax will alfo occafion a change in declination, to- «car each other, wards the fouth preceding, of 3",701 ; and, as this will not agree with the obferved motion of a, we muft account for it by a proper motion of this ftar direftly towards the north. The real annual velocity required for this purpofe, muft be 1,3925. The apparent motion of x, by parallax, at the diftance we have placed this ftar, will be 2'',832 towards the fouth pre- ceding ; and, byadigning to it an annual proper motion of the velocity I,3'354, in the direction of 73® 10' north preiSbding its own parallel, thecf!e6l of the folar parallax and this proper motion together, will have caufed the fraall ftar, in appear- ance, to revolve round «, fo as to have produced all the changes in the angle of pofition which my obfervations have given ; and, at the fame time, ex. will have been feen to move from its former place, at the annual rate of 0", 105 in right afcenfion, and 0'^,12 in declination towards the north. In this manner, we may certainly account for the phenomena of the changes which have taken place with the two ftars of a Geminorum. But the complicated requi files of the motions which have been expofed to our view, muft furely compel every one who confiders them to acknowledge, that fucb a combination of circumftanccs involves the hrgheft degree of improbability in the accomphfliment of its conditions. On the other hand, when a moft fimple and fatisfadory explanation of the fame phenomena may be had by the etfeds of mutual at- traction', which will fupport the moving bodies in a permanent iyftem of revblution round a common centre of gravity, while ' at ihe fame time tliey follow the direction of a proper motion which this centre may have in fpace, it will hardly be poftible to entertain a doubt to which hypothefis we ought to give the preference. As I have now allowed, and even (hown, thepoflibility that the phonoiwena of the double ftar Caftor may be explained by proper motions, it will appear that, notwithftanding my fore- going arguments in favour of binary fyftems, it was neceftary, on a fornjer occafjon, to exprgfs myfeH in a conditional man- ner,* I ON FRUIT TREES. ^ 227 iner,* when, after having announced the contents of this Paper, I added, " Jliould tliefe obfervations be found fiijiciently conclu- five ;" for, if there (hould be aftronomers who would rather explain the phenomena of a fmall ftar appearing to revolve round Caftor by the hypolhefis we have laft examined, they may certainly claim the right of aflenting to what appears to them moil probable. (To be continued.) XII. On ^ Nature of the Varieties of Engrafted Fruit-TreeSi with a Plan for increafing the Number of New valuable Fruits, By T. S. Dyot Bucknall, E/^. M. Pf. To Mr. CHARLES TAYLOR. SIR, . - , »30iVIE friends have requeued that I would introduce another Introdu£lion, Paper on the Nature of the valuable Varieties of engrafted Fruits, as they are of opinion that the EiTay in the 17th Vo- lume of the Tranfa6lions of the Society is not fufficiently ex- tended for a fubjed fo important to the Fruit-growers, and thofe interefted in the productions of Fruits. As a proof of ray willingnefs to make the Orchardift as perfedt as I can, I beg you to prefent my compliments to the Society, with t|ie following elucidations. This is a fubjed in rural oeconomy which ought to be much Importance* belter underftood than it is, in order to enable the planters to judge of the forts proper to be planted, either as an article of pleafure, profit, or recreation ; as much of the credit of the plantation muft arife f«jm judicioufly choofing Trees of the beft, new, or middled -aged forts, and not of the old worn- out varieties, which latter cannot, in the planting of Orchards in common fituations, ever form valuable Trees , and muft end in the difappointment of the planter. Engrafted Fruits, I have before faid, and I now repeat, are Grafted fruits ate not permanent. Every one of the kaft refleaion muft fee that not permwient. • See Phil. Trans, for 1802, page 486. t Sgciety of Arts, xx. 144. Q 2 there 523 *^N FRUIT TREES. there is an eflential diflbrence between the power and energy of a feedling plant, and the tree which is to be raifed from cuttings or elongations. The feedling is endued with the ener- gies of nature, while the graft, or fcion, is nothing more than a regular elongation, carried perhaps through the feveral re- pealings of the fame variety; whereas the feed, from having been placed in the earth, germinates and becomes a new plant, wherever nature permits like to produce like in vegelation ; as in the oak, beech, and other maft-bearing trees. Thefe latter trees, from each paffing through the ftate of feedlings, are perfedly continued, and endued with the fundtions of forming per fe6t feeds for raifing other plants by evolution, to the continuance of the like fpecies. §■ The varieties This is not the cafe with engrafted fruits. They are doomed continued by ]^y nature to continue for a time, and then gradually decHne, for a time, till atiaft the variety is totally loft, and foon forgotten, unlefs recorded by tradition, or in old publications. Reafon, with which Providence has moft bountifully bleffed fome of our fpecies, has enabled us, when we find a fuperior variety, to engraft it on a wilding ftock, or to raife plants from layers and cuttings, or even to raife up the roots, and thus to multiply our Iburces of comfort and pleafure. This, however^ does not imply that the multiplication of the fame variety, for it is no more, fliould laft for ever, unlefs the fpe- cies will naturally arife from feed. Procefs of raifing Nature, in her teaching, fpeaks in very intelligible lan- fruits, and lu- guage, which language is conveyed by experience and obfer- grafting. vation. Thus we fee that among promifcuous feeds of fruits of the fam'e fort, one or more may arife, whofe fruits fliall be found to poffefs a value far fuperior to the reft in many diftin- guifliable properties. From experience, alfo, we have ob- tained the power, by engrafting, of increafing the number of this newly-acquired tree, can change its country, give it to a friend, fend it beyond the feas, or fill a kingdom wilji that fruit, if the natives are difpofed fo to do. Thus we feem to have a kind of creative power in our own hands. From the attention lately paid to the culture of engrafted Fruits, I hope vve are now enabled to continue a fuppofed happily acquired tree, when we can find it, for a much longer duration than if fuch variety had been left in the ftate of un- aflifted nature ; perhaps I may fay for a duration as long again, or ON FRUIT TREES. 229 or fomething more. After thefe fanguine expectations, I may Procefs of raifi«g reafonably be afKcd, to what does all this amount ? for here crelfiif "them by there is no direct permanency — and why ? The why is very grafting, obvious — becaufe the kernels within the fruit, which are the iQQd of the plants' for forming the next generation of trees, will not produce their like. I allow they may do (o acci- dentally ; but nothing more can be depended on. For example, fuppofe we take ten kernels or pips of any apple raifed on an engrafted ftock ; fow them, and they will produce ten different varieties, no two of which will be alike ; nor will either of them clofely referable the fruit from whence the feeds were colledled. The leaves alfo of thofe trees raifed from the fame primogenious or parent flock, will not aSluallj/ be a copy of the leaves of any one of the varieties or family, to which each is conne6led by a vegetable confanguinily. I intentionally ufed the word aSiually, becaufe a refemblance may be found, though not much of that is to be expelled. I beg that what has been laft mentioned may not be taken as a difcouragement to attempts for railing new varieties. I was obliged to fpeak very ftrongly, in order to place the cul- ture upon its true foundation. I think it need not be obferved, that there is no acquiring a new variety, but through the means of a feedling plant ; and therefore whoever willies to fucceed mud attempt it that way, or wait till others in their planta- tions may more fortunately produce it. In choofing the feeds, that apple is moft likely to produce the cleared and fined plants, whofe kernels are firm, large, and well ripened. The fize of the fruit is not to be regarded; for large apples do not always ripen their fruit well, of rather for cider the fmall fruits are generally preferred for making the ftrongeft, higheft-flavoured liquor. And from what I have been able to colled in the cider-countries, it is there the opi- nion, that an apple fomething above the improved crab pro- mifes the beft fuccefs. This advantage alfo attends the prac- tice : if there are no valuable apples raifed from that attempt, thefe wildings will make excellent ftocks to engraft upon. Gentlemen who adually employ themfelves in attempting to acquire new varieties, (liould remember that they ought to feled all the fets, from the bed of apple-quick, whofe appear- ance is in the leaft degree promifing, and plant them together, «l fach a dillance as to allow each to produce its fruit, which will 95D ^^ FKUIT TRHES. \v»H happen in about twelve, fifteen, or eighteen years. Mf Jriend Mr. Knight, who undoubtedly is the firft in actual ^^'^ertious for procuring ihefe happily acquired new varieties, has had two plants bear fruit at fix years old, and one at five. 'J'iie cider-countries have ofi'ered feveral premiums for pro- curing new varieties, and (bme with good effeft. Premiums have been given both (o Mr. Knight and Mr. Alban. When the new variety is to be raifed Irom a valuable ad- mired apple, I (hould recommend the placing thefe feeds iiv a garden-pot, filled with mould from an old melon-bed ; carrying the pot into a retired (ituation near the water, and giving attention to run the plants to as large a tize us is con- venient within eighteen months. W ilh this view, the pot Ihould be placed in the green-houfe the firft winter ; and when the plants are afterwards to be let out in the fpots, tlicy /hould not be placed under the drip of trees, or mucix cxpofed to the winds. Two inftances have been mentioned, the improved crab, and moft admired apple; but prudence fays, try all forts, and fomething probably will arife ; and the procefs is attended with little trouble or expence to a perlon who conftantly re- iides in the country ; yet, after all this fcientific care, the apple may want flavour, and be in other refpects nothing better than a common wilding. It is an undoubted fad, and worthy of obfervation, that all the ditferent trees of the lame variety have a wonderful tendency to fimilarity of appearance among themfelves ; and that llie parent flock, and all engrafted from it, have a far greater relemblance to each other, that can be found in any part of the animal creation ; and this habit does not vary to any extent of age. Fails refpeaing -^^ ^" encouragement in attempting to increafe the number engrafted fruits, of new valuable fruits, we can prove that the golden pippin '^'iil'eQcI,lc. '^ "^^^^® Englith. The red-ftreak, a leedling of Hereford- fliire, if not raifed, yet was firfl brought into notice by Lord m Scudamore, and was for a long time called Scudamore's Crab. The Stire Apple was accidentally raifed in the Foreft of Dean, in Gloucefterfliire, and took the name of Forcfi Stire. The cider made from this apple was the ftrongeft the country ever produced, according to any living record. The Haglo- crab, the befl cider fruit now remaining, was difcovered 5 in OK F*UIT TREE«. Qgl m the parifti of Ecloe, on the banks of the Severn ; and, about F^fls refpeain^ r r r ' . 1 r . . • engrafted fruits, fixtj' or leventy years ago, many Icions were taken trom this their degree of tree by Mr. Bellamy, and engrafted on feedling flocks about pcrmaucncc, &ca Rofs. Thefe are now grown old ; and, to afcertaln the age of the variety, 1 went with Charles Edwin, Elq. to Ecloes, in hopes of feeing the primogenious of this family. The proprietor of the efiate acquainted Mr. Edwin that it had cea(ed to bear years ago, and was cut down. Thole at Ro(s are but poor bearers now, and 1 fliould fuppofe the variety muft be 14^) years old, though Marftiall, who wrote in the year J 7 86, mentions thefe trees were prolific, and he fuppofcs the fort to be about eighty years old ; but, from prelent ex- perience, it muft be much more. The Tinton Squafti-pear is of Glouceftecfliire; the Barland and Old-field were near Ledbury, Herefordihire. The two laft pears clearly bear the names of the two fields where they were raifed. The Bar- land fell about fix years ago, vifibly from weight and longe- vity, which was fuppofed to l?ave been about 200 years. There had beeif many other names of efiimation handed down to us, though the realities are now totally worn out, and have ceafed to exili. Can any better proof be defired, that en- jjjrafted fruits are not permanent, then the regret we feel for the lofs of thefe old valuable fruits. t To make my paper as fliort as convenient, I have dwelt only on the apple and pear ; yet all the engrafted fruits are under the fame predicament of the feed not producing its like, and the ofifspring in time falling into a nothingnefs of growth and bearing, though that fpace of time muft certainly depend on the natural longevity and hardnefs of the fort, foil, pofition, care, &c. All thefe are more fully exprelTed in the papers publiflied in the different volumes of the Tranfadions of this Society, and the two volumes of the Orchardift, wherein the 4?vhole fyftem is extended, to form a rational culture ibr the management of Standard Fruits. It fliould be remembered, that as I am now alluding to tlie flate of adual permanency, fifty years are to be accounted as nothing; and as often as we come to that point, we are com- pelled to refort to our firft affertion, ** That engrafted fruits are not permanent, they being continued from elongations, and not raifed as a repetition of feeds." This is the only rational 232 ^N FRUIT TREES.. Fads rcfpeaing rational way as yet introduced of accounting: for the lofs of engrafted fruits, , 11/1, • . r r • «. ... r ^ % their degree of ^"G Valuable old varieties ot fruits. Should a better fyftembe permanence, &c. introduced, I fliail readily adopt it; but this fufficiently anfwers the purpofes of the planter. Some years ago, from due inveftigation and thorough con- viftion, I propagated this principle ; and it was publiflied in the 17th volume of the Society *s Tranfa6lions, in the follow- ing words: " All the grafts taken from this firft tree, or parent iiock, or any of the defcendants, will for fome generations thrive; but when this firft flock fliall, by mere dint of old- , age, fall into adual decay, a nihility of vegetation — the defcendants, however young, or in whatever fituation they ' maybe, will gradually decline; and, from that time, it would be imprudent, in point of profit, to attempt propagating that variety from any of them. This is the dogma which muft be received. I do not expeft a diredl aflent, neither do I with it, for it (hould be taken with much referve ; but it is un- doubtedly true." Tiiefe confiderations fiiould ftimulate us in fearching after new varieties, equal, or perhaps fuperior to thofe of which we regret the lofs. Obferve that, from the time the kernel germinates for apple-quifck, fliould the plant be difpofed to form a valuable variety, there will appear a regular progreffiye change, or improvement, in the organization of the leaves, until that variety has flood, and grown fufficient to bloflbm and come into full bearing ; that is, from the flate of infancy to matu- rity ; and it is this and other circumflances, by which the in- quifitive eye is enabled to form the feledion among thofe ap- pearing likely to become valuable fruits. But from that time the new variety, or felefled plant, compared with all the en- graftments which may be taken from it, or any of them, thefe lliall (hew a raoft undeviating famenefs among themfelves. It is readily allowed, that the different varieties of fruits are eafiiy diftinguillied from each other by many particulars, not only refpecling their general fertility, and the form, fize, fhape, and flavour of the fruit, but alfo the manner of the growth of the tree, the thicknefs and proportion of the twigs, their (hooting from their parent ftem, the form, colour, and confidence of the leaf, and many other circumflances, by which the variety can be identified; and were it poffible to engraft ©N FRUIT TREES, 233 engraft each variety upon the fame flock, they would ftill Fa^s refpeaing retain their difcriminating qualities, with the mofl undeviating thSTdegree of * certainty, permanence, &c. The proper conclufion to be drawn from the ftatement in the laft paragraph, is this — that were any one to put the thought in pradice on a full-grown hardy or crab flock, it would produce an excellent proof that engrafted fruits are not permanent. For if twenty different varieties were placed to- gether, fo that each might receive its nurture from the fame flem, they would gradually die off in aftual fucceffion^ ac- cording to the age or flate of health of the refpedive variety, at the time the fcions were placed in the flock ; and a difcri- minating eye, ufed to this bufinefs, would nearly be able to foretell the order in which each fcion would aflually decline. Should it alfo happen that two or three fuckers from the wild- ing (lock had been permitted to grow among the twenty grafts, fiich fuckers or wilding (hoots will continue, and make a tree afier all the reft are gone. A further confequence would re- fult from the experiment : among fuch a number of varieties, each of the free growers would ftarve the delicate, and drive them out of exiftence only fo much the fooner. ft mufl be obferved, that this fuppofed ftem is the fofter-parent to the twenty fcions, and real parent to the fuckers ; and thofe the leaft converfant with engrafted fruits know the advantage ac- iquired from this circumftance. And here it is worth while remarking, that a Gafcoyne, or wild cherry, will grow to twice the fize that ever an engrafted cherry did. By an experiment we have had in hand for five years, it will appear that the roots and fiem of a large tree, after the firft fetof fcions are exhaufted or Worn out, may carry another fet for many years ; and we fufpe6l a third fet, provided the engrafting is properly done, and the engrafter choofes a new variety. Now the Ripfton pippin, of Yorkfliire, is the fa- vourite, as being a free grower and good bearer, with fine fruit. This however may be certainly depended on, that when a new apple is raifed from feed, if a fcion were placed in a retired fituation, and conftantly cut down, as a (lool in a copfe-wood, and the apple never fuffered to fulfil the intentions of nature in bearing fruit, the pra6litioners of the following ages may fecure fcions from that ftool, to continue the variety much longer. Hence, though I have written as much as is in my 234* ON FRUIT TREES. Fa£hrerpeaing my power againfl permanency, yet I have taken fome pains engrafted truits, . ■" ' ,**, , ^ -^ i ^ , „. . , their degree of "> allure the planters, that lorecaft, leleaion, pruning, clean- ptrmdnence.&c.Jinefs, and care, will make the orchards turn to more profit, lor the riiing generations, than what they have done for the laft hundred years. To place the nature of varieties in its true light, for the information of the public, I muft maintain, that the different varieties of the apple will, after a certain time, decline, and a(f^ually die away, and each variety, or all of the fame ftein or family, will lofe their exiftence in vegetation; and yet it is a known fact, and mentioned in the 17 th volume of the Tranfa •/- i i nature of the be made m the eye itlelt to produce diftinct vjfion by the rays pencils of light J of the feveral pencils, as R. B. remarks, but much more on a circumftance commonly noticed by authors, but by him over- looked, namely, the degree of convergence between the op- tical axes of the two eyes which is required to avoid fquinting, or ANSWERS TO OPTICAL QUESTIONS. 2i37 or the phenomenon of two images. In proof of this, if he will take two pens or pencils or other pointed objedls, and, fliutting one eye, endeavour to apply tlieir points end-wife to each other but on the by moving them acrofs the line of fight, he will find how ^'y^^^''^^^^^^^^^* much lefs precifely one eye can give a judgment on diftances, perfpeftive. than both eyes. And our judgment of diftant objects is efta- bliflied not at all upon the nature of the pencils, but on the perfpedive arrangement or angular magnitude of the objects together with their gradual obfcuration (from the interpofed mafs of air) called aerial perfpedtive. Hence we find that the feveral parts of a well drawn tketch of mere lines, and flill more of an excellent painting, give all the notions of diftance, though there cannot be any difference in the divergence of the pencils of light to correfpond with that effeft. The confciouf- nefs that a body is approaching or retiring arifes little if at all from any change in the pencils ; in near objedts that notion is rather gained from the required change in the optical axes, and in thefe and all diftant objects it is almoft entirely produced by the angular magnitude becoming larger or fmaller, while we contemplate the appearances. Thefe truths will explain the image in the concave mirror : The image In For 1. When the face is near the mirror, the image is feen by ^ concave niirroF r , • I . . , , . :; ^^^'"s to retire a great convergence ot the optical axes, which becomes lefs and advanct and lefs as the obferver retires, at the fame time that the image ^^°^ ^^^^'^ itfelf fubtends a lefs and lefs angle: — It therefore, for both reafons, appears to retire. 2. At a greater djftance the image feems ftationary while the obferver retires, becaufe the angular enlargement of the image is nearly compenfated by its dimi- nution from increafed diftance; and 3. At a ftill greater dif- tance the angular enlargement increafes fo faft that the image feems rapidly to come forward until it is loft in confufion.— If both eyes be kept open, the obferver has a contiderably* accurate notion of the real diftance of the frame, which, to- gether with the confufion of two different images prefented to the eyes, may lead him to have the fentiment of a mere angu- lar enlargement; but if one eye be covered, the notions of re- treat, ftationary pofilion, and rapid advance of the image will infallibly be adopted. 2. With regard to the concavo-convex mirror, none of the pencils of light are brought truly to a focus. If we conceive the furface of the mirror to be divided into zones by lines 4 drawn the effects of a concavo-convex mirror* 238 ANSWERS TO OPTICAL QVESTIONS. Explanation of drawn perpendicularly acrofs the (hortef! arc of convexity thai palTes through the vertex ; and thefe hnes to he mdefinitely near each other; — or to fpeak lefs mathematically, if the mir- ror were divided into fmall parallel ftripes, drawn ri^ht acrofs its concavity ; — each of thofe fmall zones or ftripes will refledl the light of any diftant obje^ to a focus before the mirror with- out any fenfible error; whence it will diverge in a kind of flat pencil; and thefe pencils themfelves will not be parallel to each other, but will diverge from a point behind the mirror or vir- tual focus; fo that this laft divergence of the pencils will be at right angles to the divergence of the rays that compofe them. If therefore we attend to the portion of light which enters the eye from what may be taken to be a radiant point of the image, in this cafe, we (hall perceive that they cannot be brought to a correct focus on the retina. For if the eye be adjufted to the place of convergence before the mirror, the focal fpot will be elongated in the dire6lion of the arc of convexity; and on the contrary, if the eye be adjufted to the virtual focus of the con- vex, or point of divergence, the rays of the pencils will not be duly collected, but will render the fpot on the retina oblong in the diredion of the arc of concavity. Neverthelefs, if the dillance of the eye be fo great, as that the difference of ad. fuHment for thefe two points (hall not produce any fenfible ef- feci of this kind, the whole image will appear fufficiently neat and diftin6l, though a little deformed; that is to fay, thofe di« menfions which are governed by the concavity, will be fome» what greater than thofe governed by the convexity; becaufe .as we may affirm, the concave mirror is nearer the eye than the convex. From (his general explanation, it will be eafily underftood that tho image raufl difnppear and become utterly confufed by the quantity of crofs aberation, when any attempt is made to examine it with a convex lens; and that it will be impollible to form an image of the fun or of any other objed upon the furface of paper or other fimilar material. In fa6l the refleded light from the fun confi/dered as a himinous point, will converge before the mirror to a line or cauftic curve of which I have not yet confidered the properties ; but which, if the concave mirror were cylindrical, would be a right line at the dillance of half the radius from the vertex. .J-j^ is not neceffary after what has been faid to enter into any fuller explanation of the reafon why the im#ige is inverted, (that is to fay either right handed w upfide-down) with regard r to ANSWERS TO OPTICAL dUESTlONS. 239 to the relative pofition of its parts conlidered acrofs the con- cavity, and the contrary along the lines oF convexity; — or, while thefe lines have their pofition altered by rotation of the mirror, the image itfelf w ill alio appear to revolve with twice the velocity. Thefe effeds, as well as that of the extreme diftortion of the image, feen when the objed is within the cen- tre of concavity, will be eafily apprehended by the reader, whofe notions of optics are fufficient to enable him to under- ftand the preceding paragraph. 3. The enlarged appearance of the fun and moon at low Why the (ky altitudes or near the horizon, and the apparent flatnefs of the and^^the fun and concavity of the fky have been explained, as my correfpondent moon large in obferves, by reference to the diminithed light of the heavenly *^= ^onion. bodies, when it pafles through a long portion of the atmof- phere, and likewife to the notions of diftance which are ob- tained by looking over a long row of terreftrial objeds. That is to fay the explanation is grounded on the fuppoiition or no- tion of greater diftance along the horizontal line deduced from confideration of the aerial and the geometrical perfpe6tive. The obfervations and objections of R. B. appear to me to be perfectly well founded. I think the effedl is produced almoft entirely by the geometrical perfpeflive, not of the houfes, trees, and other land objeCls, but of the clouds themfelves. When the clouds are in low diftinft flakes with clear openings be- tween them, the angular magnitude both of the clouds and their intervals will be greater near the zenith, and will dimi- nifti as the zenith diftance encreafes, fo as on fome occafions to exhibit the appearance of objeds running out to an immenfc cli^ftftnce in the concavity of an extremely flat dome. On the contrary, when lofty towering mafles of clouds rife from the horizon to a confiderable elevation facing the fetting fun, or otherwife fo circumflanced that the tint of the whole mafs fliall be very little varied, the mind, fo far from adopting the notion of an extended dome in that part, fliall receive the impreflion of an immenfely elevated wall, with very little curvature as it rifes. Both thefe conditions are not unfrequently to be feen at one and the fame time, and the flcy is then,, according to the obfervation of R. B. very far from exhibitinij; a figure of regular dimenfions. A great viariely of intermediate forms and groups of the clouds often prefent themfelves, by which the apparent figure of the (ky will be made to difl^er from thefe extreme 9afes. When the Iky is perfectly and clofely clouded, we hav^ 340 SHAVING WITH WATER. have perhaps very little notion of an apparent figure unlefs from our former habits, or from the angular motion produced by the wind. This will be greateft near the zenith, and by (hewing us that the clouds over our heads are nearer than the others, will give us aconviflion of the figure of aflat arch. Cotton in ink recomnricnded. Shaving with water. Ufeful Notices refpe^ing various ObJeSls. By a Correjpondent, Cotton in Ink, R. B. A HE ancient pra6lice of putting cotton in ink is almoft en- tirely given up. But when we confider that the colouring matter of ink is merely a precipitate, in the ad of flow fub- fidence, and that the gum as well as the Gallic acid, are fub- je6l to fpeedy decompofition or mouldinefs by expofure to the air, we fliall fee good reafons for refuming it. The black fe- cula is kept fufpended by the cotton ; the fluid is prevented from circulating by hea,t, cold or mechanical agitation, and confequently prefents a very fmall furface to the air; and laflly the method of dipping tends to keep the pen clean and in good condition. I can take upon me to aflTert that ink in cotton is blacker, more durable, and much lefs liable to become mouldy. The latter effedt may be almoft entirely prevented byoccafion- ally turning the cotton upfide down, that is to fay, every two or three days Shaving zvith Water. IN fome of your early numbers the operation of fiiaving has been rather amply difcufled by yourfelf and correfpondents. I have nothing to add in the way of reafoning to what has been there brought forward; but I take this opportunity of noticing ^ fadl. Long ago it was obferved to me that the foap anfwers no other purpofe than that of clearing the fliin, in proof of which it was aflerted that the face fo cleaned may be fhaved quite as well without the lather as with it. I made trial of this procefs, but did not find it fucceed, becaufe I wiped the fkin dry. But I have fince found that if the beard be well waflied with foap, and then with clear, water, the operation of fliaving may be very efl^e<5tually and pleafantly performed, while the water continues upon the fkin. The effects are that the razor cuts more keenly and clofely, and the fkin feems to be much lefs tender. I leave your other correfpondents to reafon and difcover the caufe of the excellence of this method ; in the mean time I ftiall continue to ufe it, unlefs a ftill more con. fiderable improvement fhould be made. J O-USrM-A L. OF NATURAL PHILOSOPHY, CHEMISTRY, AND 'fli'k "-Amc APRIL, 1804.. ARTICLE I. '..,■■ : ' ^ )' t ^■, ■ > " ; ^^ Experiment proving the Advantage of Perifcopic SpeSlacles. Coni'- municated in a Letter from W. H. Wollaston, M. D. F.R.S. . ToMr.NZCHOLSON. SIR, • ■ '■ : - " JL HE opinion given by Mr. Jones, in your laft Journal, re* Mr. Jones's fpefling the improved form of fpedacle-glafles, on which I had improved fpec- delivered my fentinients in the number preceding (p. 144,) in- tacle glaffes, duces me to addrefs you once more upon that fubjedt. It appears wholly uhneceflary to follow Mr. J. through his referred to ex- various obfervations, or to remark upon the experiment by " which hedecfciveshimfelf; becaufe all doubt of the advantage of the perifcopic glaflTes may be removed by the follovving dired comparative trial, which any perfon vyho choofes can make without difficulty. ' -I have before me two gl^fTes, eath of four inches " pofitive With tht form focus," as propofed by Mr. J. the one double-convex, which ^^^gnded by Mr". i^i his judgment is pronounced to be " indubitably the bejl and Jones, 'inoji convenient that can be devifed*' (p* 194) ; the other a con- 'tavo-convex, or menifcus^. which he thinks "evidently the •ivor/t of the tzvo for afpedUtckr^gh/s," (p. 197*) When I fix the former at the diftance for moft diftin£t vifion the extent of ' ;Oppofite to a printed oaavo page, and approach my eye to the cimpwed'with ' Vol. \ai.-~ApRiL, 1804, R gMs, that by th* 24^2 REMARKABLE STRATA OF FLINT. perifcopic glafs -glafs, I cannot without pain read quite twenty-four linef?; but * upon fubftituting the perifcopic glafs fixed in the fame pofition, I can with exfe difcern every word in the page, which contains forty lines. —or rather as The enlargement of the field of view obfervable in this trial is futficient to evince the fuperior utility of the perifcopic glafs ; but were there occafion to compare more nearly the circular areas that may be fe^n with equal diftinclnefs, they would be found to differ by a ratio as great as that of three to one. A correfponding This dilFerence is of courfe more evident in glaflTes of fo high flialJovve^^lcnfes. po^^r than in thofe generally ufed by long-fighted perfons for common purpofes; but it cannot be doubted, that a corre- fponding, though fmaller, inequality fubfifts wherever there is the fame diflimilarity of conftrudion, even when the focal dif- tance is longeft. ponclufion. The advantage in queftion is therefore indifpirtably proved by dired experiment; to the notelty of it Mr. J. himfelf has unintentionally contributed very fatisfaftory evidence ; but as to its importance, thofe alone, who have the misfortune to la- bour under any defedl of vifion, muft ultimately decide. I remain. Sir, • . Your obliged humble fervant, Mardi 20, 1804-. W. H. WOLL ASTON. IL AddUional Ohftrtations onfome remarkable Strata of Flint in tht Jjle of Wight, in a Letter from Sir Charles Englefield, Bfirt. F. R. S. /o John Latham, M. D, F. R. S. andL. S* (See Page 183 o/ the prefent Number,) Dear Sir, Obfcrvations on 1 FEEL much flattered at the notice taken -of my Paper on remarkable ' ^ijg ^.h^jj; pjts in the Ille of Wight by the Linnean Society ; ftrata of flint in , , .^ , , ? r .l • the Ifle of ^"^ ^^ i wiln to render my account or the very curious appear- Wight. ances obferved by me in them as perfe6l as I can, the follow- ing additional obfervations on the fubjedl made during a fecond vifit laft year are, by your favour, fubmitted to the Society. » Linnean Tranfa^lions, Vol, VI, Tlie KEMARkABLE STRATA OF FLINT, 243 The pits I laft year infpefled are as follow, beginning from Obfertatlons on Brading pit, which is at the eaftern point of the great ridge, the Ifle of where the valley of Brading-haven interfeds it, and feparates^'S^'^* it from the Yaverland-hill, which terminates in the fea at Culver and Bembridge. A road cut into the chalk above Knighton. Afhley-down pit, about three miles eaft of Newport. A pit very near to and fouth'of Cariibrook caftle. The cliffs ^n^l eaves of Frefliwater bay, both eaft and weft of the valley which interfe6ls them entirely and runs from Frefti water to Yarmouth. The Yaverland chalk is therefore the only part which I have not examined; and little doubt can be entertained of its fimilarity to the reft of the range, to which it evidently belongs. In Brading pits fome flints appear in detached nodules, and thefeare found and unbroken. The inclined ftrata of flijit are vifible, but not to advantage, owing to the manner of working the pits. In thefe ftrata the flints are univerfally (battered, forae intoabfolute powder, others inlogrofl^er powder and fragments mixed. But betides thefe , ftrata, the chalk in this pit is divided by vaft perpendicular filTures, as fmooth as plaifter walls, and in fome of thefe fif- fures flint has formed, which appears broken like that in the ftrata. The road above Knighton only juft cuts into the chalk ftra- tum, but all the flints vifible in the banks are extremely fliat- tered. The pit at the weft end of-Aftiley-down, near two large bar- rows, is the moft extenfive and fatisl'adory of any I have feen. The perpendicular face of the chalk, where worked, is not lefs than fifty or fixty feet, and its direction is at right angles to that of the ftrata, and parallel to their line of dip: — of courfe they are feen to very great advantage. The ftrata feems to dip northward more rapidly than in any other place where I could obferve them. The angle of inclination is from 75 to 80 degrees. There are not layers of flints between every layer of the chalk. Some of the chalk is peculiarly folid, and rifes in very large matTes affeding a cubic form. Their folid vein is from twenty- five to thirty feet thick, and is in ftrata from three to four feet. In all this folid part there are very few flints. Both above arid below this harder bed (fpeaking of the ori- ginal pofition of the ftrata) the ch^lk is fofter, and has more R2 flints 244 REMARKABLE STRATA OF FLINT. Obfervations on flints in it. The ftratified flints in this pit are full as much ftrTta'of fUnt ^^^^^6^^^ ^s any I had feen. The nodules are not at all broken, in the Ifle of Many of the ftratified flints are much defaced in this pit by an Wight. admixture of pyrites, fo as to be quite opaque like a coarfe jafper, and thefe flints are much fofter than the others^ as is al- ways the cafe in the impure flints. In the chalk pits near Carift)rook the ftrata are not fo vifible as in the pits north of the c.aftle (defcribed in the firft papers) but the flints are to the full as finely, though perhaps not fo generally broken. In one flint I obferved that though it lay in its bed undifturbed, chalk as if in a fluid ftate had run into one of the fifl'ures. Every appearance of this pit indicates that the chalk, fince its (Gratification, has received a moft violent fliock. The chalk at Freftiwater bay appears in high perpendicular clifl?*s, particularly on the weflern fide of the bay. Both on the eafl:and welt the ftrata dip northward near 80 degrees, and the dip feems to run eaft and weft very regularly. The weftern clitf has a very regular and perpendicular face to the eaft ward ; and here the parallel direction of the ftrata, each feparated by a thin line of black flint prefents a moft curious appearance. The flint here is often found in thin plates of confiderable ex- tent, fometimes not above an inch thick, and feems formed from each fide of the fpace which it fills, as the exterior parts (or tliofe neareft the chalk) are the pureft and blackeft, and it is gradually whiter towards the middle, where there is often a foft line of chalk included between the two plates of flint. All the ftratified flints are more or lefs fliattered, and fome are re- duced to very fine powder. The cave at Frefliwater, which is really a beautiful as well as a very curious one, is formed by the adionof the fea on thefe nearly vertical ftrata. They are of different hardnefs, 2«id all interfecled with filTures at right angles to the ftrata. When the fea ads on and wears away a foft ftratum, a gallery is formed, and the upper parts of the ftra- tum between fiflure and fiflure drop out, much in the fame way as bricks are apt to do out of the flat arch over a window, the harder contiguous ftrata ferve as walls to the gallery, but are by degrees perforated in different parts, and become irregular pil- lars, fupporting the vaft weight of the hills above, until the a6tion of the fea weakens them fo far that they fall, and a part of the face of the hill goes witli them, fo that the cave is con- flantly, although flowly, changing its form. 4 Larger REMARKABLE STRATA OP FLINT. ^45 Larger mafles of the harder ftrata, defended by their flint obfervatlons on coating, alfo ftand up in the bay as infulated rocks of different ^^^^^^^f^i^nt (liapes, and much refembling the Needle Rocks, which are jn the IHeof exadly of the materials and formed by the fame procefs. In Wight. this part of the chalk flratum, I faw feveral foffils remain which I had fought in vain in the pits 1 had vilited. One was lingu- lar, it had the appearance of part of a very large (hell, regu- larly flriated, and almoft flat, I have often feen fmall frag- ments apparently of a limilarflieil in chalk, but never a large piece. It was fo firmly fixed as not to be removed without a chiffel, which I had not. To thefe obfervations on the chalk of the ifland, I mufl: add, that this whole range, although really chalk, is much harder than the chalk of the South-downs, infomuch that the carpen- ters cannot ufe it for drawing lines, but import chalk for that purpofe from Portfdown hill above Portfmouth. They alfo call the ifland chalk by the name of marie, which is, however only the Britifli name for chalk, and appears in many compound names, fuch as Marl-borough on the Wiltfliire chalk hills, and the very figni/icant one of Albemarle, or white chalk. As I have made fome further obfervations on the fouthern range of hills which form the back of the ifland, I willtrefpafs on your patience a little longer, particularly as they in fome degree contradid, or rather corred, what I had advanced on that fubjefl in my former letter. When the northern front of thofe hills is viewed from Afliley down, the ftratura of ftone mentioned in my former letter as lying diredly under the chalk of St. Catharine's and Dunnofe hills, appears every where to maintain an horizontal pofition ; and fo in its general pofition, particularly in its northern front, it certainly does, but juft behind the village of Ventnor, the ftratum entirely difappears, as if it had been ingulphed in a great chafm, and a deep and narrow valley runs winding into the chalk hill of St. Boniface, though it does not penetrate through it, which feems the remains of the fifllire into which the ftone had funk. The appearances of the .great ftone ftratum, from Niton eaftward to Ventnor are noted as follows in the journal made on the fpot. On an attentive Jnfpe6lion of the ftrajta of the under clifl^, it appears that the great ftratum of rugged and laminated ftone, I i ; which 246 KEMARKABLE STRATA OF FLINT. Obfervations on which firft appears at the weft fide of St. Catharine^s, and ftrau of flint whence ranging eaft ward, forms the front of the cliff, over- in the Ifleof hanging the Underway dips in its fouthern face gently to the ^^5^^* eaftward. The cliffs at Mirables are much higher above the fea than thofe at St. Laurence, and from thence they decline, till at the opening of the hill above Ventnor they totally dif- appear. A fmall crag juft peeps out of the eaftern face of this dell, and the whole hill of St. Boniface is^ as far as can be feen, compofed of chalk. As however this, like all other chalk hills, is in the ftate of a fteep Hope, covered with turf, perhaps by giving into its face the ftony ftratum might be difcovered. It is alfo to be obferved that the chalk, which is not vifible above the rock at Mirables, begins to appear foon after, and grows gradually thicker as it proceeds eaftward. At St. Laurence it forms a thick cap to the rocks ; and at Steephill Shute, its Ihick- nefs is very much encreafed, and foon after nothing but chalk appears in St. Boniface's hill. In what form the rock re-ap- pears at Dunnofe to the eaft of St. Boniface, I have had no opportunity of examining. I (liould not, dear Sir, trouble you with thefe defedive ob- fervations, but that every notice, however imperfect, may be of ufe when conne6ted by future obfervations, and that they may ferve as a ftlraulus to other travellers, who often go over this beautiful Hne of country, to turn their attention to its fin» gular natural phenomena. I fend vou two fpecimens of the broken flints, one from Brading, the other from near Caritbrook, but the tickets are miflaid, and I am not fure which is which, I remain, &c. Tilney-Street, May 26, 1 80 1 . III. - Account of a Machine for fweeping Chlmnies, by aBlafi of Aif^ Jn a Letter from Mr. J. C. Hornblower, Engineer, To Mr. NICHOLSON, Dear $ir, Introdufticn. J. SHALL be much obliged if you will allow me a page oi two in your Journal for a defcription of a machine I have latel; got up for the purpofe of cleanfing chiranies from foot, Mj MACHINE FOR SWEBPING CHIMNIES. 247 wiih js, if poffible, to keep alive the fpark that has been kindled by a truly philanthropic individual, with a view to reftore a degraded clafs of our fpecies to their rank in civil fociety. The machine, as it is conftrufted folely for the purpofe mentioned above, is certainly novel in its intention, and without a better acquaintance with its principle and operation than the public are at prefent in polTeffion of, it is not likely to gain that notice which in my judgment it is entitled to. There is a propenfity Propenfity to in us to turn into ridicule any thing that will admit of a ridi- jions, culous conftru6lion, or afford an opportunity for the difplay of our wit; and fuch is the unfortunate circumftance of this ma- chine, that grinning takes precedence of gravity the moment it is announced as a candidate for the gold medal at the Adel- phi. However, happy for it, and thrice happy for me, there, is a tribunal which can judge fairly and fcientifically of its merits, for which I prefent it as follows. The body of t^e machine A, Plate XIII. is made of copper, Defcriptionof of about Sib. to the fquare foot, and its contents are abou^t ^^^^^^P^"[^J^ three cylindrical feet. In the middle of the cover, which is which air is foldered on, is a fyrintje or condenfer, having its handle as '^°"'^5"^^'^» '^PT^* ,, ^ r ^ r I - - r , municates with appears above the cover. On one tide or the cover is mierted a tube charged a crooked pipe, having a valve opening inward in its inner or ^"^'^ ^""^'f . lower. end; the ftem of which comes up through the pipe, and being blown up terminates with a button C. The pipe is continued by a flex- '^.^ chimney ible leather one, to which is united the tin plate tube B B.- foot^^ °^" This tube B B has a crofs bar of tin plate fixed edge-ways in the bottom or breech of the tube which detaches from the leather pipe fomewhat like a piftol barrel, leaving a piece of tube about fix inches remaining to the leather pipe, into the bottom of which this cafe bar is fixed, and ferves to receive a. charge of fmall gravel, having a piece of paper firft laid on the crofs bar ; the other part of the tube is then to be replaced, and the air-veffel fuppofed to be full ; the valve is preffed down by a little lever accompanying the machine, and its contents are difcharged into the (haft of the chimney; and if there is any foot worth fweeping away, it will come down. Obfervations concerning the Machine. I do not pretend to have made any new difcovery in the This operation conftrudion or application of the machine, for it is well known jf fin^i^ar to that a mulket has often been applied for the fame purpofe^ and up the'cSamey* with 248 MACHINE rOR SWEEPING CHIMNIES. with as good effe6l as need be, barring the hazard of fettlng fire to the foot; and indeed, when a chimney has accidentally taken fire, it is the beft and moft expeditious mode of putting it out, at leaft of bringing the foot into a fituation by which it may be extinguithed. Eftimate •£ the I have faid that the vefTel contains nearly three cylindrical velocity of the feet, and we cannot crowd three atmofpheres of air into it, in extei\ded air, and , . r its ejffea in the which cafe there will be 42 lbs. per inch fquare at round nura- chimneyj toge- bers, preffing againft the charge in the tube, or rather againll ther with that of , , , , , . r • , ,- . . the gravel. the valve, the tube being 2^ inch diameter, which amounts to 168 lbs. for the whole area. This air will all be difcharged in one fecond, the mean velocity of which may be fairly reckoned at 60 feet, in that time having impetus in itfelf fufficient to carry away any foot of confequence in a chimney of 100 feet high ; but when we take into the account the charge of gravel, being alternately incident and reflected on all fides of the chimney, we need not fear to affirm that it is perfectly applicable to its intention. Additional tubes j^ render it as univerfal as poffible, there muft be another chimiiies. tube, to be occafionally ufed, when the fide of the chimney near the fire place is gathered over in order to bring the throat of the flue over the fire, as at Fig. II. from a to b, or it ftiould be in feveral pieces, to conform to the height of this gathering, and in this cafe the charge muft be at the upper fiflure at b, and the pipe flayed as perpendicularly as can be conveniently done; for which purpofe there is a piece made to fix on the pipe, having two flems, as Fig. III. which if put in the bear- ing fide of the pipe, will keep it upright and in the crater of , , the flue. The machine thus conftru6ted is to be laid on a little truck, and tranfported from houfe to houfe, with a gallon of gravel to begin with; becaufe until it has obtained the good opinion of the public, it would not be neceflfary to attempt fuch regulations as would afterwards be deemed requifite to facilitate the operation. Trial at the This poor thing, brought forth under other difadvantages Sodet "If Arts befides its Angularity, was conduaed to the Adelphi, to un- in the Adelphi. dergo an eventful trial, in competition with fome others, who had no fuch fingularity to be imputed to them; they being all defcendents of the flock of one family, the reraoteft relation between each not being more diftant than coufin-german. — Other machines Qne of them however poflefled great originality and ingenuity alfj exhibited ' in Ifhcre. MACHINE FOR SWEEPING CHIMNIES. 249 in the defign. It confifted of a congeries of bruihes, which in Bruihes. preparation for a6tion were collapfed by their conftru6tion fo as to admit of being thruft up the chimney with very little re- fiftance, and when it had gained the top, on pulling a firing, it expanded tothedimentions of the chimney, and brought the foot down before it; but from want of a mechanical attention to its conftru6lion, fome parts being too ftrong, and fome too flight, it broke in the firft experiment. Another (very elegant inftrument) was prefented to the A finglebruft. committee, confifting of a large brufli, fuch as I have feen in fome churches to fweep down the cobwebs, with a feraper at- tached to it; lengthened to the height of the chimney by a feries of whalebone rods, whipped together as in the conftruc- tion of waggoners* whips, very accurately jointed to each other. Indeed this was eflential and common to them all, except one; and that was a brufh, not to be fent up the chimney, but down it, by getting on the top of the houfe, and putting it into the chimney, and fo letting it fall to the bottom. However, it Notion that the was faid, they would all do very well but mine, as a machine frf„°t'eronly to like that was adopted to a redilinear flue only ; whereas theirs a ftralt flue, had fo many joints and other properties to conform to a curva- ture, that they would be fure to go through a crooked flue as j»mb iikai well as a ftrait one. When the late Do6lor Johnfon had any thing advanced to The fame him of the marvellous kind, his way of hefitation to admit it, °^"'^^* was by faying " It may be very true, but it is impoflible." — So I fay with refped to the difpofition of thefe rods, when (et in competition with a volume of air going at the rate of fifty feet in a fecond from the lower part of the chimney to the top. What is there to flop it? What is there to pre vent its conform- ity to the curvature or ano^/es, if you will? The manner in which thefe bruflies a6l, let their conftru6lion To hloto down be what it may, is by ftriking off" the foot. What does a boy ^nzJZ^lsto within the flue with the brufli in his hand? To be fure iweep- Jweep it down, ing is the moft appropriate term for what he does; but then, unlefs, we attend to the peculiarity of the adion, and confi- der how far it is poflible to effe<5l that fweeping by another mode of action, we fliall not get any further than the boy in the flue. But is it not as eafy to conceive of a quantity of air being put into aftion along a road or a ftreet, fo as to fweep f way the dufl before it ? No; you will fay, it blows it along; k but £ any of the candidate's inventions, any further than a fair thruft up th» chimney' 'f With another in the fame room I fuppofe. Aecquni 252 CAUSE OF THE CHANGES OF RELATIVE IV. Account of the Changes that have happened, during the laji Twenty" five Years, in the relative Situation of Double Stars ; xvith aii Invefiigation of the Caufe to which they are owing. By Wil- liam Her scHEL, LL. D. F, R. S, From the Philofophical Jranfaaiom for 1 803 . * (Concluded from Page 221.) I Obfervationsand J[ SHALL now enter into a more detailed examination of the ipefting the feveral angles of pofition I have taken at different times, and changes of rela- fhow that they agree perfeflly well with the appearances which tlve fituatlon in rauft ari(e from the revolution of a fmall ftar round Caftor. A ftars extremely near each other, calculation of thefe angles may be had, by finding the annual motion of the fmall ftar, from the change of 21® 54'', which has been fliown to have taken place in 23 years and 142 days. Accordingly, I have given^ in the firft column of the following table, the lime when the angles were taken. In the fecond, are, the angles as they were found by meafure ; they are all in the norJ,}»-pi"eceding quadrant. The third column contains a calculation from the annual motion of 56^,18, obtained as before mentioned: it (hows what thefe angles fliould have been, ac- cording to our prefent fuppofition of a revolving ftar. And the laft column gives the difference between the obferved and calculated angles. iTimes of the obfervations. Obferved angles. Calculated angles. Differences. Nov, .5, 1779 - 1 32^ 47' 1 32" 47' 0® 0' Feb. 23, 1791 - | 22 57 1 22 11 + 0 46 Feb. 26, 1792 - 27 16 21 16 + 6 0 Dec. 15, 1795 - 13 52 17 42 - 3 50 M'^rch 26. IHOO 18 8 13 41 4- 4. 27 r.pnl '23, I.SOO 10 :^o 13 37 - 3 7 vDec 3:^ 1801 - 7 58 ; 12 2 - 4- 4 ,J^n. iOif 1802 r 10 58 . 12 . 1.... - 1 8 Jan. 23. J 802 - 10 28 11 59 -• I' 31 Feb. 28, 1802 - 13 0 11 53* + 1 7 Ff b. 11,1 803 - 7 53 11 0 1 - 3 7- 29 March 23, 1 803 13 23 10 54 4 2 March 27, 1803 1 10 53 10 53 0 0 On avri:^osiTioN OF d.ouble stars. 253 \ Oh looking over the fourth column of this table, it will be Obfervatlonsand found, that the differences between the obferved and calculated fp/^i"g t^e ' angles are not greater than may be expeded, confidering that changes of rela* mod of the early meafures are fingle, and cannot have the ac- ^^^5 eSremely" curacy which maybe obtained by repetition. Even as they near each other* are, we muft acknowledge them fufficient to afcertain the gra- dual change in the angle of pofition of the two flars. In one place, the difference amounts to fix degrees; but it will foon appear, that a more accurate annual motion gives a calculated pofition which takes off much of the error of this meafure. In a converfation with my highly efteemed friend the Aftro- nomer Royal, he happened fome time ago accidentally to men- tion, that Dr. Bradley had formerly obferved the two ftars of a Geminorum to ftand in the fame diredion with Caftor and Pollux. It occurred to me immediately, that if the time of this obfervation could be nearly afcertained, it would be of the greateft importance to the fubjedt at prefent under conlider- ation. For, (liould Dr. Bradley*s pofition be very different from a calculated one, it would induce us at once to give up the idea of a revolving ftar. The obfervation was made by Dr. Bradley with a view to fee whether any change could be perceived in the courfe of the year, by which the annual parallax of the ftars might be difcovered. Dr. Matkelyne, who had this informa- tion from Dr. Bradley in converfation, had made a memoran- dum of it in his papers. He has been fo kind as to look for it ; and, as foon as he found the note, he fent me the following copy, which I have his permiflion to tranfcribe. " Double jiar Cajior. No change of pofition in the twojlars : If* the line joining theniy at all times of the year, parallel to the line *' joining Cajior and Pollux in the heavens, feen by the naked ** eye." Dr. Matkelyne informs me, that (he obfervation muft have been made about the year 1759 ; and alfo mentions, that he himfelf verified the fa6l, as to the line joining the two ftars ap- pearing through the telefcope parallel to the line joining Caftor and Pollux, in 1760 or 1761 ; but that he did not examine it at various times of the year. The advantage of having an angle of pofition obferved in 1759 by Dr. Bradley, and fo foon after verified by Dr. Maf- kelyne, will give us an addition of 20 years to our period. On calculating the right afcenfion and polar diftancs of Caftor and Pollux 254 CfX.'JSE OF THfi CHANGE OF RELATIVE Obfcrvstionsand Pollux Tor November 5, 1759, it appears, that a line drawn fpeS!ne*the ' ^^^^ PolluK through Caftor, muft have made an angle of changes of rela- 56^ 32' north preceding with the parallel of that ftar ; and, this ftlrstSe'^cl'" being alfo the pofition of our double ftar, we have an interval near each other, of 43 years and 142 days, for a change of 45° 39', from the time of Dr. Bradley's obfervation to that of my laft meafure of the angle. By this we are now enabled to corre6t our former calculation, which was founded upon a.fuppofition that the firft angle of pofition I had taken vv as perfe/^ ; but this could hardly be expeded, and on examination it appears that the meafure was 2® 40' too little. The annual motion, by our increafed period, is 1° 3',1 ; and the computation of the angles of po- fition in the third column of the following table, as well as the differences contained in the fourth, ate made according to this motion. Times of the obfervations. Obferved angles. Calculated angles. Differences. Nov. 5, 1759 - j 56^* 32' BG'^ 32' 0° 0' Nov. 5, 1779 - 32 47 35 29 - 2 42 Feb. 23, 1791 - | 22 37 1 23 36 - 0 39 Feb. 26, 1792 - | 27 16 1 22 32 + ^ 41- Dec. 15, 1795 - | 13 52 I 18 32 - 4 40 March 26, 1800 | 18 8 1 14 3 + 4 5 April 23, 1800 | 10 30 13 5S - 3 28 Dec. 31, ISOl - 7 58 12 12 - 4 J4 Jan. 10, 1802 - \ 10 53 1 12 10 - I 17 Jan. 23, 1802 - | 10 28 i 12 ■ 7 - I 39 Feb. 28, 1802 - | 13 0 1 12 I + 0 59 Feb. 11, 1803 - 1 7 53 1 11 1 1 - 3 8 March 23, 1803 | 13 23 1 10 54 + 2 29 March 27, 1803 j 10 53 10 53 0 0 When the refult of this table is compared with that of the former, it will be feen that my obfervations agree not only very well with Dr. Bradley*s pofition, but even give more equally divided ditlerences than beTore, fo that the excefs and differ- ences counteract each other better than in the firft table. The time of a periodical revolution may now be calculated from the arch of 45^ 39', which has been defcribed in 43 years and 142 days. The regularity of the motion gives us great leafon to conclude, that the orbit invvhich the fmall fiar moves about POSITION OF DOUBLE STARS. ^^ about Caftor, or rather, the orbits in which they both move Obfervationsanci round their common centre of gravity, are nearly circular, and J-pea'ng^he^' at right angles to the line in which we fee them. If this Ihould change of rela^ be nearly true, it follows, that the time of a whole apparent ftaJ'stxtremel'" revolution of the fmall ftar round Caftor, will be about 342 iiear each other, years and two months. y Lconis, Our foregoing difcuffions will greatly abridge the arguments which may be ufed, to fliew that this liar and its fmall com- panion are alfo probably united in forming a binary fyftem. But, in order to give more clearnefs to our difquifition, we iliall follow the arrangement which has been ufed with a Ge- minorum, and prefix the fame letters to our paragraphs. Then, if any one article fliould appear to be not fufficienlly explained, we need but turn back to our firft double ftar, where the fame letter will point out what has already been faid more at large on the fubje(5l ; and an application of it may eafily be made. The diftance of the ftars y and x, as I fliall again call the fmall one, has undergone a vifible alteration in the lafl 21 years. The refult of a great number of obfervations on the va- cancy between the two ftars, made with the magnifying powers of 278, 460, 657, 840, 932, 1504, 2010, 2589, 3168, 4294, 5489, and 6652, is, that with theftandard power and aperture of the 7-feet telefcope, the interval in 1782 was J of a diameter of the fmall ftar, and is now |. With the fame telefcope, anct a power of 2010, it was formerly f of a diameter of the fmall ftar, and is now full 1 diameter. In the years 1795, 1796, and 1798, the interval was found to have gradually increafed ; and all obfervations confpire to prove, that the liars are now i a diameter of the fmall one farther afunder than they were for- merly. The proportion of the diameter of y to that of x, I , have, by many obfervations, ellimated as 5 to 4. The firft meafured angle in 1782, is7** 37'north following*; and the laft, which has been lately taken, is 6° 21' fouth tbl- * In my fecond Catalogl^e of double Stars, (Phil. Tranf. for 1785, page 48,) the angle of pofition is 5® 24'. This was taken April 18, 1783 ; and, not being acquainted with the motion of the fmall ftar, I fuppofed it to, be more accurat* than the former meafure. lowing. 056 CAUSES OF THK CHANGES OF RELATIVE Obfcrvationsand lowing. The fum of thefe angles gives 1 3** 58', for the change fpeaing the " ^^^^ ^^^ taken place in 21 years and 38 days. To account for change of reia- this, we are to have recourfe, as before, to the various motions t° t'tdr °f 'he three bodies, near each other. Single Motions. (a) The motion of x alone cannot be admitted, lince it is known that y Leonis is not at reft. The annual proper motion of this ftar, according to M. De la Lande, is + 0'^38 in right afcenfion, and 0'^04< in declination towards the fouth. (b) 7 cannot be the only moving body; becaufe its mo- tion in right afcenfion only, which, in 2 1 , 1 years, at the parallel of y, amounts to 7'^49, would have long ago taken it away from the fmall ftar. ^ (c, d, e,) The fun cannot be the only moving body ; becaufe its motion in right afcenfion will not account for that of 7 Leonis, which ftar therefore cannot be at reft. And, if we were willing to give up the former aflTumed folar motion, in order to fix upon fuch a one as would explain the motion of r, we fliould be under a iieceflity to contradict the united evi- dence of the proper motions of many principal ftars which are in oppolition to it. Double Motions, (/) When two motions are propofed, we cannot fix upon 7 and X for the moving bodies, unlefs we ftiould fet afide the folar motion, and this, we know, cannot properly admit of a doubt. (g) That we cannot allow O and x to be the two bodies in motion, follows from the infufficiency of the folar motion to account for that of 7, which muft be real, or at leaft partly fo. (A) If O and 7 are the moving bodies, the given fituations of X, in the years 1782 and 1783, point out an apparent motion of ar, which muft be intirely owing to the folar parallax ; and, therefore, thofe who will admit this hypothefis, muft grant the difcovery of the motion of the folar fyftem, and of the propor- tional parallax of the two ftars y and x. Let us however exa- mine whether any motion of the fun, fuch as we can admit, will account for the change of pofition and diftance pointed out by my obfervalions of the fmall ftar near y Leonis. The i»081T10N OF DOUBLE STARS.' Q^'J The joint efFed of proper motion and parallax, has carried y Obfervatlons anrt from its fituation in 1782 to that where we now find it. The l"^^!"^^' ''^^ ipecting the fmall ftar, having all this time, in appearance, accompanied y, change of rela» muft have gone through a fpace of 7^98, in a diredion whicl) Jj^^/f^^f,'^", '" makes an angle of 8^ 30' fouth following with the parallel of „gaf each other. y, in order to be at its prefent di fiance from it, and at the fame time to have undergone the required change of its angle of po- lition. Now, as the fuppofition we are examining requires this fmall ftar to be a6iually at reli, it will be neceiTary to ailign to the fun an oppofite motion of the fame velocity, in order to make that of x only an apparent one. The confequence of this will be a retrograde motion of the fun, which it is well known cannot be admitted^ Motion of the three Bodies, (i) A motion of all the three bodies, is the only way left to explain the phenomena of our double ftar ; and I (hall noW again point out the very particular circumftances vvhich it is requifite fliould all happen together, to produce the intended effea. ILei the motion of the fun, with the fame annual velocity 1, as in the cafe of a Geminorum, be dire6led towards x Herculis. Then the effed of this motion will (hew itfelf at the place of y Leonis, in the annual velocity of ,3314, and in a direftioh which makes an angle of 31** 1 1'' fouth preceding with the pa- rallel of thatftar. In this calculation, I have admitted thedif- tance of the largeft of the two ftars of 7 from the fun to be 5> that of a- Geminorum being 2. But, if any other diftance fhould hereafter be con(idered as more probable, the calcula- tion may be ea(ily adapted to it. The confequence of the pa- rallax thus produced on y Leonis in 21,1 years, will be an ap- parent motion of 2''',788 fouth preceding^ in the abovemen- tioned direction ; and, on i, it will be in the fame time, and in the fame direction, l'',09i. As the fmall ftar muft not be too near y, we have, in tlie calculation, fuppofed it to be at the diftance of 4 from O. The real annual proper motion of y is required to be 3,5202; and its direction muft make an angle of 3** 40' north following with the parallel. B.y this motion alone, y would have palTed Over a fpace of 9^'87 in 21,1 years; but, when it is combined with the apparent motion ariling from parallax, the ftar will come into its prefent fituation. Vol. VII.— April, 1804. S The ' 258 CAUSE OF THE CHANGES OF RELATIVE Obfervatlons and The real annual motion of x muft be 4,6294, in a dire6lIon fpeSingThr ^° 20' fouth following. This will carry it over 9^74, in 21,1 changes of rela- years; and, when combined with the apparent motion which trve fituatlon in ^^e folar parallax will occafion, both together will bring it to ftars extremely . ^ . , n »ear each other, its proper ditlance from yLeonis, and to a fituation which will agree with the laft obferved angle of pofition. From what has been faid, it is again evident, that not only as many particular circuraftances mufi: concur in explaining the phenomena of y Leonis as we have pointed out with a Gemi- norum^ but that a very marked condition is added in our fecond double ftar, which requires an adjuftment of velocities in y and X, which fiiall a]fo fit the fame folar motion that was ufed in a Geminorum. And this proves, that every additional double flar whicii requires the fame condition in order to have its ap pearances explained, will inforce the argum.ents which have been ufed, in a compound ratio. If, on the other hand, we have recourfe to the fimplicity of the known effcds of attraction, and admit the two ftars of oiir prefent double ftar to be united in one fyftem, all the foregoing difficulties of accoundng for the obferved phenomena will vanifli. Whatever may be the proper motion of the fun, the parallax arifing from that caufe will affeft both ftars equally, on account of their equal diftance from the fun. The proper motion of y Leonis alfo may be in any diredion, and of any given velocity, fuch as will agree beft with aftronomical ob- fervations; fince the motion of a fyftem of bodies will not in- terfere with the particular motion of the bodies that belong to it, fo that our fecondary ftar will continue its revolution round the primary one without difturbance. It will now be neceifary to exainine the obferved angles of pofttion, and to compare them wiih calculated ones ; but, as there has been a change in the diftance of the two ftars, it is evident that, if they revolve in circular orbits, the ftiuation of the plane of their revolution muft be conftderably inclined to the line in which we fee the principal ftar. Let N F S P, Fig. 2, be the orbit in which x revolves about y placed in the centre. Suppofe a perpendicular to be ercded at 7 leading to O, not expretfed in the figure. By an obferva- tion of Feb. 16, 1782, we have the aiiglc F y .r = 7^^ 37' north following ; and the proportion of the apparent diameter of y to that of X has been given as 5 to 4. It has alfo been afcer^ tained POSITION OF DOUBLE STARS* ♦ 259 lamed, that the vacancy between the apparent diameters, Obfcrvationsand when the firft angle of pofition was taken, was | diameter of j-pg^^""^^^' the fmall flar; aaid the lall angle of pojSt ion being 6° Sl^changcsof rela- . foulh following, with a diliance between the ftars of | diame- ^^^ fituation In ,r n • r , "^''^ extremely . terot the fmall itar, we obtain (he two points or centres of the near each other. fmall ftars ^cjc', through which an ellipfis abxx'cd maybe drawn about 7. This will be the apparent orbit in which the fmall ftar will be feen to move about 7, by an eye placed at O. And the inclination of the orbit to the line in which we fee the double flar, will be had fufficienlly accurate to enable us to give a calculation of the feveral angles of pofition that have been taken. The ellipfis we have delineated ftiews that the fmall flar, in its firtl fituation x, could not be much paft its conjunc- tion at b, and that, confequently, in palling from x to x\ the • parts of the apparent elliptical arch, which are projedions of the real circular arch h A", would be defcribed in times nearly proportional to the time in which the whole arch has been de- fcribed. Upon thefe principles, the third column of the fol- lowing table has been calculated. Times of the obfervations. Obferved angles. Calculated angles. Differences. Feb. 16, 1782 - 7° 'il'nf 1 7*» 37^ , 0^ 0' April 18, 1783 - 5 24 nf 6 51 - 1 27 Jan. 24., 1800 - 3 16- sf 1 4 15 ! - 0 59 Feb. 19, 1800 - 3 23 sf 4 IS i - 0 55 March 26, 1800 | 3 47 .s/ 1 4 22 1 - 0 35 Jan. 26, 1802 - | 6 4 .v/ 1 5 35 1 + 0 29 Feb. 10, 1803 - 1 3 33 sf 1 6 16 1 - 2 43 March 22, 1803 • | 6 32 sf \ B 20 1 + 0 12 March 26, 1803 | 6. 21 sj: \ 6 21 1 0 0 The difference between the calculated and obferved angles, contained in the fourth column of the preceding table^ is fo little, that we may look upon the gradual change of thefc angles as eftablifhed by obfervation ; and we may form a calculated efti- mate of the time which will be taken up by the mutual revo- lution of the two ftars. The apparent places xx\ being referred to their real ones, give the arch h h', which has been defcribed in 21 years and 38 days ; and this arch, feen from the centre y, is about 6* 20' : it follows, that the length of a whole revolu- tion of our fmall ftar round y Leonis, will be about 1200 years. S 2 e BoolU 2^C) ^AUSE Of THl CHANGES ©P RELATIVE I Bootis, Obfervations and This beautiful double ftar, on account of the different colours infcrcnccrs re- ©f the ftars of which it is compofed, has much the appearance changes of rela- of ^ planet and its fateUite, both ftiniing with innate but diifer- tivc ikuation in gntly coloured light. »ear MchoTher. There has been a very gradual change in the diftance of the two ftars ; and the refult of more than 1 20 obfervations, with different powers, is, that with the ftandard magnifier, 460, and the aperture of 6,3 inches, the vacancy between the two ftars, in the year 1781, was \\ diameter of the large ftar, and that it now is 1|. By fome earlier obfervations, the vacancy was found to be confiderably lefs in 1779 and 1780; but the7-feet mirror then in ufe was not fo perfed as it Ihould have been, for the purpofe of fuch delicate obfervations. By many eftimations oC the apparent fi:^e of the liars, I have fixed the proportion of the diameter of £ to that of r, as 3 to 2. Auguft31, 1780, the fir ft angle of pofition meafured 32** 19' north preceding*; / and, March 16, 1803, I found it 44.** 52', alfo north pre- ceding : the motion, therefore, in 22 years and 207 days, is 12^ 33'. It fliould alfo be noticed, that while the apparent motion of a Qeminorum, and of y Leonis, is retrograde, that of « Bootis is diredl. A proper motion in this ftar, if it has any, is iiill unknown ; our former arguments, therefore, cannot be applied toil, with- out fome additional confiderations ; and, as many others of my double ftars will ftand in the fame predicament, I fhall give an outline of what may be faid, to fliow that this, and probably many of the reft, are alfo binary fyftems. Single Motions, (a — e) If I Bootis is a ftar in which no proper motion can be perceived, we may infer, from the highly probable motion of the folar fyftem, that this ftar, which is of the third magnitude, and on that account within the reach of parallax, muft have a real motion, to keep up with the fun, in order to prevent an * The angle of pofition, in my fiifl Catalogue of double Stars, Phil. Tianf. for 1782, page 115, is 31° 34' (it fliould be 54) ftorth preceding. This will be found to be a mean of the three firft meafuies hereafter given in a table of portions. apparent POSITION OF D0UBLE STARS. " 261 •pparent change of place, which muft otherwife have hap- Obfervations and pened. In this cafe, no fingU.' niotion can be admitted to ex- J-pe^""^^' plain the phenomena of our double liar. But, if a real proper change of rcla- motion of t Bootis fliould hereafter be afcertained, the argu- ^j^^ fituation in ..,,,,, ftars extremely Itients we have ufed in the ca(e of 7 Leonis, will lead to the near each other, fame conclufion. Double Motions. (/) t and X cannot be the moving bodies ; and our former argument (/) will apply to every double ftar v\ hatfoever. {g) O and X cannot be alone in motion; for, if no motion in I can be perceived, it muft move in a fimilar manner with the fun, and none of the three bodies will be at reft But, if its proper motion fliall hereaf'er be found out, it muft either be exactly the reverfe of the f )lar motion, and therefore only an apparent one; or it will be more or lefs different. In the latter cafe, all the three bodies muft be in motion ; in the former, the exacl quantity of the folar motion will be difcO" vered, and the relative parallax of many ftars may be had by obfervation. (A) If O and « are the two bodies in motion, and if at the fame time no motion in e can bo perceived, then the apparent motion of x muft be intirely owing to the difl^erent efle6t of the folar parallax on i and r; but (he effefl of the folar parallax on X, can only be in a doedion contrary to the motion of the fun, which, being north following the fmall ftar, whether it be nearer or farther from us than e, muft have an apparent motion towards the fouth preceding part of the heavens. But this is diredly in oppofition to my obfervation of the motion of the fmall ftar, which, thefe laft 23 years, has been direded tCf» wards the north following. Motion of the three Bodies, (i) Let the motion of the fun be again towards x Herculis j then, if no motion in e Bootis be perceivable, it muft movQ exaftly like O. Highly improbable as it is, let it be admitted. Then, in addition to this extraordinary fuppofition, a third motion is alfo required for x, which, aided by the (olar parallax, is to carry it like wife within a quarter of a diameter of f, into the fame place where, though unperceived, the large ftar has hQQn carried b^ its own motion j that i^, in order to be appa- rently 3 0(52 CAUSE OF THE CHANGES OF RELATIVE Obfcrvatlons and rently at reft, the fan, e Bootis, and its fmall companion, rauft- fpealnrthr' ^'' move exadly alike, fetting aiide the very little difference in change of rela- the pofition and diftance of the fmall Jftar, which, in the whole, tive fituation in amounts to little more than 6-tenths of a fecond ; than which, ftars extremely . . . ' near each other, certainly nothing can be more improbable. But, if £ (hall hereafter be found not to have been at reft during the time of my obfervations upon it, then its place will be given ; and, fincealfo the fituation of x, with refpecl to s, is to be had from my angles of pofuion and diftances of the two ftars, the cafe will be fimiiar to that which has already been confidered, in the paragraph {i), under the heed of y Leonis. I may here add a remark with regard to e Bootis, which will be applicable to feveral more of ray double ftars. In the milky- way, a multitude of fmall ftars are profufely fcattered, and their arrangement is very different from what we perceive in thofe parts of the heavens which are at a coniiderable diftance from it. About £ Bootis, which is fituated in what I have for- merly called figuratively a nebulous part of the heavens *, there are, comparatively fpeaking, hardly any ftars ; and, that fo remarkable a ftar as s fiiould have a companion, feems alraoft to amount to a proof that this very companion is, as it appears to be, a connected ftar. The onus probmdi, therefore, ought in juftice to fall to the Ihare of thofe who would deny the truth of what we may call a fa6t ; and I believe the utmoft they could do, would be to prove that we may be deceived ; but they can- pot {how that this ftar has no connexion with % Bootis. This argument will be much fupported, when we conftder that many of the double ftars in the milky-way are probably fuch as have one of the fcattered ftars, nearly in the fame line, at a great diftance behind them. In this cafe, the two ftars of the double ftar have no connection with each other; and the great number of them in the milky-way, is itfelf an indication of this effect of the fcattered multitude of fmall ftars. In the ftngle conftellalion of Orion, for inftance, we have no lefs than 43, pointed out by my catalogues ; ten of which are of the firft glafs, and yet have undergone no change of diftance or pofition fince I firft perceived them. But, with apparently infulated ftars, fuch as i Bootis, the cafe is juft the reverfe. * Sec Phil. Tranf. fpr |784, page 449. If>* POSITION OF DOUBLE STARS. 253 If, in confequence of our former arguments, and the prefent Obfervatlons and remarks, we place £ Bootis among the ftars which hold a fmaller f^^^i^^g ^he " one in combination, we may delineate its. orbit as in Plate VIII. change of rela-, -n- Q ' tive fituation in *^^S' '^' ' / ftars extremely . Let P N F S reprefent a circle, projeded into the elliptical near each other, orbit axx'bcd. e is the large ftar ; and x xf are the firfl and lafl meafured north preceding iiluations of the fmall one, as given in the following table. Times of the obfervations. Obferved angles. Calculated 'angles. Diiferences. ^Hguft 31, 1780 32'' 19' 33« 58' - I'' 39' March 13,^J781 30 21 34 13 - 3 52 May 10, 1781 - 33 1 1 34 18 - I 17 Feb. 17, 1782 - 38 26 34 40 -f 3 46 Aumilt 18, 1796" 45 32 41 4-0 1 + 3 52 Jan. 28, 1802 - 49 18 44 19 . -f 4 59 Auguft 31, 1802 46 47 44 36 1 +2 11 March 23, 1803 43 43 1 44- 52 - 1 9 March 26, 1803 44 52 44 52 0 0 The real motion from h to h' is projected into that from x to x' I and, while the elliptical arch fubtends an angle of 12^' 33', the circular one will be about 4'^ 50'. From the figure of the orbit, w^e may conclude that the fmall flar, in its firft pofition, at x or A, was not more than between 30 and 40 years pall its conjundlion; and that, confequently, the parts of the arch x a/, were nearly proportional to the times of their being defcribed. The pofitions have been calculated upon this principle; but with fome allowance for the firft ob- ferved angle, which I fuppofe to have been a little too fmall ; and, though the differences of the obferved and calculated angles are pretty eonfiderable, the obfervations are ftill fuffi- ciently confiftent to prove the gradual change of the fituation of the fmall fi:ar. * . . The quantity of the change in 22 years and 207 days, will Ihow that a periodical revolution cannot take up lefs than 1681 years. The real figure and fituation of the orbit, with many other particulars, are ftill unknown ; it is, therefore, unneceff fary to point out the uncertainties in which the inveftigation of the periodical time of the fmajl ftar about « Bootis muft long remain involved. ^ Herculis^ 264' CAUSE OP THE CHANGES OF RELATIVE C Herculis, Obfervations My obfervatlons of this (lar furnifh us with a phenomenon refpea'mg"the ^'^'^'^ '^ "^^ '" aftronomy ; it is, the occultation of one ftar by changes of rela- another. This epoch, whatever be the caiife of it, will be ftlr*stx"remel"^ equally remarkable, whether owing to folar parallax, proper ■ear each other, motion, or motion in an orbit whofe plane is nearly coincident with the vifual ray. My firft view of this ftar, as being double, was July 18, 1782. With 460, the ftars were then | diame- ter of the fmall ftar afunder. The large ftar is of a beautiful Jjluifli while j and the fmall one afli-coloured. July 21, of the fame year, I meafured the angle of pofition, 20^ 42' north following. With the ftandard power, the dif- tance of the ftars remained as before. With 987, they were one full diameter of the fmall one afunder. In the year 1795, 1 found it difficult to perceive the fmall ftar; however, in Odtoberof the fame year, I faw it plainly double, with 460; and its pofition was north following. Other bufinefs prevented my attending to this ftar till the? year 1802, when I could no longer perceive the fmall ftar. Sometimes, however, I fufpe6ted it to be ftill partly vifible; and, in September of the fame year, with 460, the night being very clear, the apparent difk of ^Herculis feemed to be a lit- tle lengthened one way. With the ten-feet telefcope, and a power of 600, I faw the two ftars of »i Coronae very diftindlly ; and, having in this manner proved the inftrument to a6l well, i direfted it to ^ Herculis, and found it to have the appearance of a lengthened, or rather wedge-formed ftar; after which, J took a meafure of the pofition of the wedge. Our temperature is feldom uniform, enough to permit the uf« of very high powers; however, on the llth of April, 1803^ I examined the apparent dilk, with amagnifier of 21 40, and found it, as before, a little diftorled; but there could not be more than about I" of the apparent diameter of the fmall ftar wanting to a complete occultation. Moft probably, the path of the motion is not quite central; if fo, (he difli will remain a little diftorted, during the whole time of the conjundion. Our prefent obferva- tlons cannot determine which of the ftars is at the greateft dif- tance; but this will occafion no difference in the appearance; for, if the fmall ftar (liould be the neareft, its light will be, equally loft in the brightnefs of the large one. .''^' • ' The POSITION OF DOUBLE STARS. Otf^rvations and Inferences refpefting the changes of rela- tive fituation in , ftars extremely . near each other. As a confirmation of the accuracy of thefe obfervatjons, we may have recourfe toa pofition of the lame ftars, deduced from the places of them, as they are given in Mayer's Zodiacal Catalogue. By two obfcrvations reduced to the beginning of the year 1756, the preceding one was S'^S before the other in right afcenfion, and 5'^3 more north than that ftar. From this we calculate the petition, which was 54** 21' 37'^ north pre- ceding. The interval from the ift of January, 1756, to the 21ft of November, 1781, is 25 years and 325 days. When this is added to the period I have given, we have 47 years and 105 days, for a motion of 24^ 2^ The annual motion, deduced from this lengthened period, which is 30',5, differs lefs than 1^ minute from that which has been calculated from my obfcrvations. With the affiftance, therefore, of Mayer^s obfcrvations, which greatly fupports our calculation, we may- conclude, that the two ftars of y Virginis revolve round each other in about 708 years. Account of the Invention of the Compound- Barrel and Winch, and its ufeful Application on a Large Scale, In a Letter from Afr.J. J. Hawkins. To Mr. NICHOLSON. SIR, IN No. 25 of your ufeful Journal, p. 50, you mention the compound-barrel and winch, as the invention of the celebrated Mr. George Eckhardt. Not in the leaft wiftiing to frbtrad from the well known in- The compound ventive talents of that Gentleman, I beg leave to fay, that, t^alfotn-*"'^ if it was invented by him, it was alfo invented to my certain vented by Mr. . knowledge, by the late Mr. Robert Mc Kean of Philadelphia, ^* ^*^ ^^^' fon to the prefent governor of Pennfylvania. 4 Mr. 2^8 «OMPOUNb BARK EL AND WJfNCH. Ini795orx796. Mr. Mc Kean communicated the idea to me a few day* Dcfcripiion. aft^r it firft occurred to him, in the year 1795 or 1796 ; his plan differed, however, in two points^ from that defcribed in your Journal ; for, firftly, he made ufe of handfpikes apphed into holes in the end of the largefl: barrel, whenever the winch did not afford him fufficient power; and, fecondly, when he found it neceifary to raife any thing above the level of his windlafs, he added two other puUies for the rope to pafs over. Dimenfionsand About the year 1797, Mr. Mc Kean ereded a faw-mill ZmTuni°^^ worked by a fleam engine, at Bordenton in NewJerfey; terrel. where he employed this crane to raife his logs, from the ground to the frame on which they were to be cut, being a height ef about twelve feet ; the circumference of the largeft barrel was about fix fee tj and its length three feet; the fmalleil barrel was of the fame length, and its circumference three feet, making the difference of their circumferences three feet ; and, confequently one turn of the barrels, raifed the log one foot fix inches ; and eight turns only were fufficient, to elevate it the height required. Its power as one This windlafs was turned with handfpikes fix feet long ; 90 twenty. which, at the place where the power is generally applied, would defcribe a circle of about 30 feet ; fo that the power obtained, is as one to twenty. The length of rope neceflary, including that which paffes round the pullies, and from thence to the barrels, is about 55 feet. A common Now in order to raife a weight 12 feet high, with a power tackle would ^^ ^^^ ^^ twenty, by means of the common block pullies, have required • /• • i • i five rimes as r>o lefs than 270 feet of rope is neceifary ; there is, however, much rope; this difference in the fizes of the ropes, that, in the former but thinners cafe fupporting one half of the weight to be raifed, whereas in the latter it has only to fuflain one twentieth part of it. This windlafs '^^^ windlafs has the peculiar property of holding the weight floes not run at any part of its rife or fall, without needing a ratchet-whee] ^own* ^^^ catch ; by reafon of the two parts of the rope pulling on oppofite fides of the barrels ; and although one pulls on a longer lever than the other, yet it is not fufficient to overcome the fridion on the axis, whiclimufl of neceffity be large, iti order fo give the requifite flrength to the machine. Itpromifes to be I have lately introduced a fmall windlafs of this kind, into fuu"'^^^'^ a piece of piachiner^ requiring altefpate elevation and de- preffionj %ALVAN1C APPARATUS. ' g^^ preffion, and find it extremely convenient ; and I have no doubt it will be adopted in a great variety of machinery when its valuable properties are generally known. I ain> Sir, Yours, &c^ J.J.HAWKINS. 11, Nat} Lijle Street, March 17, 1804. VI. Propofal for cdnjiru6iing a Galvanic Apparatus of Great Power, for the Combujition of Metals. By a Corref pendent. I.R.I. To Mr. NICHOLSON. SIR, A HE following idea of a mode of increafing to an immenfe Increafe of degree the galvanic power of inflaming metals, took its origin ^y^j*"^^ ^^^* from Mr. Wilkinfon's paper on that fubjefl in your laft Journal ; and I beg that if you think this communication can be of the fmallefl ufe to that ingenious gentleman, that you will fend it to him before publication. I can hardly think that it could have efcaped his penetra-by one fiagle tion, (though I cannot account for his omitting theobfervation) P**'^^'^ ?*''• that the natural confequence of his difcovery relative to the ratio by which the galvanic trough increafes in its power of inflaming metals, is, that the maximum of effe<5t wjH be pro- . duced (from a given furface,} by one pair only ; fo that the fame furface of metal that in his apparatus at prefent confirudt* ing and diftributed into 50 pairs, will burn 108 feet of fteel wire •5*^ of an inch thick, if concentrated into one, will have the fame eflfeft on 5400 feet of the fame wire ; an enormous in-f creafe of a power that may become as noble a prefent to the •♦rts, from fcience, as the fteam-engine has proved, I ha veal fo turned my thoughts towards making a new form Defcrlptlon of of apparatus, on the above principle, fo as to condenfe it into ^^ propofed ap- as little bulk as poflible.' Thefimple inrpe6lion of the drawing P*^*^"'* accompanying this will fufficiently illuftrate it j the fcale is of three inches to a foot, [PL XV.) it reprefents part of the ground plan of a trough, of about ten feetlong, two feet broad^ and t wo and half feet deep : the black line reprefents the copper, the dotted the .270 ^'^ """"E FASCINAflMO FACULTY the zinc, the white the acid liquor, and the fliaded part the wood: the fcale is made large for the fake ofdiftindtnefs ; two fpigots or turncocks are adapted to the end by which the liquor may be drawn off; a contrivance of great ufe, but impra6lica- ble in the prefent form j only two convolutions of the plates are exprefled, and the turns are made about three inches wide, to facilitate the foldering of the zinc plates to the copper ; the liquor is confined in as fmall a fpace as poffible, to prevent the unneceflary wafte of acid. It may alfo be con{lru6led with one metal only, on Mr. Davy's plan ; in that cafe, the fulphuret will occupy one fide of the plate, and the acid the other. Hoping that the above may merit a place in your very excellent Journal, and be of ufe to my fellow labourers •m fcietice, I remain. Sir, Your mod obedient humble Servant, I. R. I. an old Correfpondent, Edinburgh, March 13, ISOk VII. J Meuwir concerning the Fafcinatihg Faculty which lias been af- ci*^cd to the Rattle-Snake and other American Serpents, By Benjamin Smith Barton, M. D*. From the Ainerican Tranfadions, Vol. IV. FiDEM NON ABSTULIT ERROR, Naturalifts fre- NaTURALISTS have not always been philofophers. The quently too cr€» „. , , ^ ,. • , . , • t • i • t tiulous. flight and luperncial manner in which they nave examined * Since this memoir was read before the Society, it has been con- fiderably altered, and fomewhat enlarged. I hope, the alterations will render it more worthy of the notice of thofe who, like myfelf, derive plealure and happincfs from the contemplation of the works and operations of nature, on this globe, 1 fear, I fliall be thought to have treated the queftion in too dlf-i fufive a manner. I have not, indeed, laboured to be concife. if the memoir is more extenfive than was neceftarj', I flatter myfeli it will be admitted that it, at leaft, contains fome new and interei jng fafts. I fubmit it to its fate. B. S. B. This interefting paper has been deferred from the preffure of otW matter of more immediate and temporary claim. W. N. mat ASCRIBEP TO THE RATTLE-SNAKE. 271 many of the fubjedls of their fcience ; the credulity which has accompanied them in their refearches after truth, and the pre- • cipitancy with which they have decided upon many queftions of importance, are proofs of this aflertion. There is a queftion in natural hiftory that has, in an efpecial Fafcmatlon by- manner, folicited from me thefe obfervations. I mean the queftion concerning the fafcinating faculty, which has been afcribed to different kinds of American ferpents. It is my intention to examine this queflion, in the memoir which I now prefent to the Philofophical Society. Of this fafcinating faculty we have all heard and read. In many of our country iituations, there is hardly a man or a woman, who will not, when the fubjed comes to be men- tioned, ferioufly relate fome wonderful ftory, as a convincing proof of the dodrine. Children feem taught to believe it. generally bcliev- I think, it is fometimes one of the earlieft prejudices im- ^ '" menca. printed on their tender minds. It is a prejudice which often increafes with their years; and even in that happy period of life when the mind is moft firm, and the leaft propenfe to the belief of extraordinary things, the ways of which we are not capable of fcanning, I have known this prejudice fo deeply and fo powerfully rooted, as to mock the light and furenefs of fa^ls, and all the ftrength of reafoning. It is not my intention, in this memoir, to give an analyfis, or Examination of complete view, of everv thine: that has been written on the *^^ queftion ..."'. . . psopoied. fubjed. Nor is it my intention to examine the many flories, related by authors, in fupport of the fafcinating faculty of ferpents. For the firft talk, I have not leifure ; and, as to the fecond, I fliould think my time ill employed in pointing out the grofs ablurdities which feem to conftitute a neceflary part of many of thofe (lories. I think it proper, however, to obferve, that I have anxioufly fought for, and have patiently perufed, the volumes of tales publithed in favour of the do6trine which 1 mean to controvert. I aim at giving a general, though correft, view of the General view* queftion, uninfluenced by the bold aflertions of ignorance, or by the plaufible conjedures of fcience. In the invefliga- tion of the queftion, I have fought for fads : thefe have been my guides. I have ftudioufly endeavoured to follow where they feemed to lead. Perhaps, they have led me aftray. Tha gfjj ON THE FASGINATlNd f ACULTf The manner in which the fuppofed fafcinaling power of ferpents is exerted has often been related, by different writers. I (hall endeavour to convey forae idea of the bufinefs^ in at« few words as I can. Se fur'o^d ^^^ fnake, whatever its fpecies may be, lying at the bottom procefs of fnakes of the tree or bufti upon which the bird or fqairrel fits, fixes m fafcinating j^g gy^^ upon the animal which it defigns to fafcinate or en- iDther animals » '' chant. No fooner is this done than the unhappy animal (I ufe, for the prefent, the language of thofe who differ from me in opinion, on this fubjefl) is unable to make its efcape. It now begins to utter d moft piteous cry, which is well known by thofe who hear il^ and underftand the whole machinery of the bufinefs, to be the cry of a creature enchanted. If it is a fquirrel, it runs up the tree for a (hort diflance^ comes down again, then runs up, and, Jaflly, comes lower down. ** On that occafion," fays an honeft but rathfer credulous writer *> ** it has been obferved, that the fquirrel always goes down more than it goes up. The fnake ftill continues at the root of the tree, with its eyes fixed on the fquirrel^ with which its attention is fo entirely taken up, that a perfon accidentally approaching, may make a confiderable noife, without the inake's fo much as turning about. The fquirrel as before mentioned comes always lower> and at laft leaps down to the fnake, whofe mouth is already wide open for its reception. The poor little animal then with a piteous cry runs into the fnake\sjaws, and is fwallowed at once, if it be not too big. but if its fize will not allow it to be fwallowed at once, the fnake licks it feveral times with its tongue, and fmoothens it, and by that means makes it fit for fwallowing \" Other accounts It would be eafy to cite, from different authors, other ac- are not material- ^Qynl^s of the manner in which the enchantment is performed; ^ *' * or, more properly fpeaking, of the conduct, or behaviour^ of the enchanting and enchanted animals. But between thefe accounts, there is hardly a fpecific difference. There is con- fiderable unity in all the relations that I have heard, or read* * Profeflbr Peter Kalm. f Travels into North- America j containing its natural hiftory, and a circumftantlal account of its plantations and agriculture in general, &c. &c. vol. i. p. 317 & 318. Alfo vol. ii. p. 207, 208, ^09 & 210. Engliih Tranflation. London s 1770& 1771. However^ * ASCRIBED TO THE R AtTLE-SNA K^. ^7S However, thofe who wifli to examine this part of the fubje6l more fully, will, at leaft, receive fome degree of entertain- ment from the perufal of the many authors who have believed and aflerted, that ferpents poflefs a power of fafcinatirtg other ^ animals. That the belief in the exiftence of this power (hould have Credulity in the been fo general among the uninformed part of a people, ought gj^'^J^Jd-** not to be wondered at. The human mind, unenlightened by faience, or by confiderable refledion, is a foil rich in the weeds of fuperftition, and credulity. It is ever prone to believe in the wonderful, even when this belief, as is often the cafe, brings with it fears, and cares, and mifery. The bondage of the mind in fuperftitious credulity is great and heavy. Neither religion ^or virtue can give it its freedom. This it obtains from fcience. How important, then, even in this point of view, is the enlargement of the mind by fcience! ^"* '^ isftranga r» • • r I r r n • rt i i- that men of But it is, lurely, a matter ot tome aitoniinment, that this ability have belief (liould have been admitted, in all the fulnefs of its ex- alfo admitted travagance, by men of learning, of obfervation, and of genius : by thofe who have the book of nature in their hands ; that book which will, in fome future and fome happier age, eradicate many of the prejudices which disfigure, and which mock the dignity of human nature: by claflical fcholars, grown old yji thediibeliefof fimilar fables, heightened and embelliflied hy the charms of poetry; and alfo by the infidel, who denies the authenticity of fcripture-miracles, ^qw of which, even though they were not fhown to be truths, a* e more improbable than the imaginary fa6l which I am examining. I have fought to difcover the original, or fource qf this This notion Is ^ belief. I do not find any traces of it among the ancient vVriters "°^ f°^"'^ j" 5^® /••I y-> T-. Ti-1- ni-,1. writings of the 1)1 either Greece or Rome. 1 think, it is molt likely that no anciems. fuch traces can be found. Lucan, had ferpents been thought to pofiefs a fafcinating faculty in his age, and in the country in which he lived, would, probably, have availed himfelf of its exifience, in his beautiful account of the march of Cato's army through the Libyan-Defert*; and had fuch a notion prevailed in the earlier days of Lacretius, would we not find Ibme mention made of it in the poem De Rerwn Natura, one of the fined and mod varied produdions of the human mind ? Clafiical fcholars may poflibly, however, difcover the dawn * Pharfalla, lib. IX. Vol. VII.— April, 1804. T ' ©f i 274. It does not ap- pear to have originated nor to be much, if at ail, admitted among the In- dians* ON THE FASCINATING FACULfY of this notion in Greek and Roman authors, unread by me. On this fubjed, I have not puHied my inquiries as far as I wifhed to have done. It is not unhkely that I may examine the queftion more curioufly, at feme future period. It is probable that in the mythology of Afia and of Africaf, we (hall difcover fome traces of this notion, fo intimately connected with the fuperftitious credulity of a people, and even fo naturally arifing out of an imperfed view of the manners of ferpents. If we believe the Reverend Dr. Cotton Mather *, Mr. Dud- ley f , and other perfofts, who had refided in North-America, we are to look for the beginning of this ridiculous notion among our Indians. How far, however, this is really the cafe may, I think, be doubled. F^is certain that, at prefent, the opinion is by no means univerfal among the Indians. Several intelligent gentlemen, who are well acquainted with the manners, with the religious opinions, and with the in- numerable fuperftitious prejudices of the Indians, have in- formed me, that they do not think thefe people believe in the notion in queflion. My friend Mr. John Heckewelder, of Bethlehem, writes to me, that he does not recolle6t to have heard the Indians fay that fnakes charm birds; though he has 4>requently heard them fpeak of the ingenuity of thefe reptiles in catching birds, fquirrels, &c. Mr. William Bartram fays, that he never underftood that the nations of Indians among whom he travelled had any idea of the fafcinating power of fnikes j. On the othet hand, however, a Mohegan-Indian told me that the Indians are of opinion that the rattle-fnake can charm, or bewitch, fquirrels and birds, and that it does this with its rattle, which it (hakes, thereby inviting the animals to defcend from the trees, after which they are eafily caught. According to this Indian, his countrymen do not think that the fnake, in any manner, accomplithes the butinefs with its eyes. A Choktah. Indian alTured me that the rattle-fnake does eharm birds, &c. but he was honeft enough to confefs that he • The Philofophical Tranfaftions, abridged, vol. v. part ii.;| BO. 339. p. 162. •J* Ibid; vol. vi* part iii. no. 376. p. 45. X MS* note> communicated to me by this ingenious gentleman. di