mA be ee 02 ORS 58 02 a i + fi ath i} i i i i ‘ 4athe Se Soelene= os! 3 star + aestesetesy Sitesi ebaheLtichehs bert by Peer ste: Te etts sb thiet Le seed ee ~ i lis HH j ut piapar a] * h ends bere ot bebe pope ese Siipeee titers tiersat avy oes whens pebapne es bees bot i! webs be hd Le pabenes Sih ree Gast +b TTL etre Hh th shrek tit seit fees +t tS sebehesy: eee res ss os aehe tebe bene h it itis a He] Hine rertite ai ope 04 eceesresseeret’ irhed - re i thed her eateeegc te tsi tte| 33 or o ae peoerese sere? = ps fret il HyuisnHs oa FPvarhtieet Bioper tes thes She bbe ttl t+ te ” ++ {ite . it + trisesessnsatet ite: Saseet yi ve rshetit tee ePaty Se eseure: sy thcteded “4 | esters esata isents ion eva fant Li tf a? . aa is easaes tg > il iene ir ph (aS con a ky =) a a ay uty if 7 i ¥ \ us ‘ il! A i Xt TAs, ‘ hatte A ay hh Ah A | RN eb yet at ‘pti he ' ee vata! | PN Apia 1 ae ASTM i! BRAM YN Abe aly oO ainn ee i F aoert , ‘ } te) — f iI ¥ ‘ Li A , ‘pt: ‘ ne hah } ; i ) i i eT Aue N Ae hal H ai il { P 4 it ) Beye Np Pegta eae ett Ml A JOURNAL NATURAL PHILOSOPHY, CHEMISTRY, AND Pak). SAR. TF: 8: VOL. XVI. Flustrated with Cngravings. BY WILLIAM NICHOLSON. LONDON: PRINTED BY W. STRATFORD, CROWN COURT, TEMPLE BAR; FOR THE AUTHOR, AND SOLD BY J. STRATFORD, No. 112, Hoxsorn-Hrxz. —— 1807. ; é 2 y | yioe 2 apeth ee me i >. aidar Ct, oh) ena ret eR ; eho’ Aaa: oaahes udkt . oes Lid cy : 3: wie ‘an! Se P. rey Ae a { a Py hiss yaa F Ea ot dob ote * te My : ay. hb ac 8 % ne tt lag he ‘ a ae | y. ¢} ae ie of tae eat ' - @ ao "usa M . CRE alte } ; te WE ris Me ie or ii PORTIS: | “ voy ss Pts pee W au ce abut aes hie x one. “is veto odie Tt Ad ay ‘a Wate P43 mtu, : fei JM gue ee ar t: soaitli ok 5, e is ast. 8 L aii’ 5; uh L. - ane rene iat aoe 9 cus + A * . ie \ magi wad . af Bigg ; Ptah feat ii Pe . q mtr ‘bueval A-nnith Ws hs L Wie “es 4g % y, Bus Me ~ i _ Se re Ses Gee 2 ae ‘ ie = + - pel 2a a que baie. a a: “a: a ot “sae. ai 4eeh's syetnl eal | Riss Ege, pe TT Bi nes =o] Sees ant’: aiden) ty 6 tal fi whe fiblanabuas . 7 A ‘onaaeaiatt beve vd, TH meh vou h <3 ena vd eatooA guiliesd 20} ehadza hl 0 tea Soy sake VE r9y0 aden uncer biteneit aii: PREFACE. Tue Authors of Original Papers and Communications in the present Volume are, G. Cumberland, Esq.; X.; Mr. John Tatum, Jun.; Mr. John Webster; Mr. W. Skrimshire, Jun.; G. €.; John Bostock, M. D.; Mr. J. Hume; R. B.; Mr. Knox; T. Thomson, M.D. F. R.S. E.; Dr. Halliday; Sir H. C. Englefield, Bart. M. P. F.R.S.; David Brewster, M. A.; A.; A Constant Reader. Of Foreign Works, Dr. Carradori; M. Montgolfier; M. Bouillon Lagrange; M. Ch. Hersart; Professor Proust; M. De Lalande; Samuel Mitchell. : And of British Memoirs abridged or extracted, Mr. John Gough; Mr. William Watson; Dr. J. A. Hamilton, Dean of Cloyne; Rev. James Little; Thomas Andrew Knight, Esq. F. R.S.; Matthew Flinders. Esq.; Mr. W. Hardy; Mr. Andrew Flint; James Smithson, Esq. F. R.S.; G. Mitchell, M. B.; Patrick Neill, A. M.; Mr. Peter Her- bert; Mr. John Antis; J.C. Curwen, Esq. M. P.; John Pond, Esq.; Sir John Sinclair, Bart. M. P.; Dr. William Roxburgh; Mr. H. Steinhauer; Rev. Peter Roberts, A. M.; Dr. Cogan; Rev. William Richardson; Mr. George Gilpin; Mr. S. Grandi; Mr. Neill Snodgrass ; Thomas Egan, M. D. F. R.S.; William Alexander, M. D.; John Alderson, M. D.; Rev. Gilbert Ausein, M. RI. A.; Mr. Edward Martin. Of the Engravings the Subjects are, 1. A Diagram by Mr. John Gough, to illustrate the Doctrine of mixed Gases ; 2. A very simple Scale for Drawing the Vanishing Lines in Perspective, by G. Cumberland, Esg.; 3. Figures by Dr. Herschell exhibiting the singular Outline of the Disk of Saturn; 4. Three Figures exhibiting the Acoustic Experi- ment of the Invisible Girl: 5. An expanding Band Wheel for driving Machinery, by Mr. Flint: 6. A new Door Latch, -by Mr. Antis: 7. An improxed Book Case Bolt, by Mr. Peter Herbert: 8 Mr. Hardy’s Compensation Balance for a Time Keeper: 9. A Calorimeter for measuring the rela- tive Effects of Fuel, by M. Montgolfier: 10. Apparatus used in the Manufactory of forged Iron Vessels: 11. An Astronomical Circle, by Mr. Troughton: 12. A Drag for raising the Bodies of drowning Persons. by Dr. Cogan: 13. Sir H. C. Englefield’s Method of adjusting the Transit In- strument: 14. A new Astrometer, by David Brewster, A. M. ; 15. Mr. Snodgrass’s Methods for heating Rooms by Steam ; 16. Apparatus for transferring Gases over Water, Mercury, &c. by the Rev. Gilbert Ausein. TABLE TABLE, OF; @ONITENTS TO. THIS SIXTEENTH VOLUME. JANUARY, 1807. Engravings of the following Objects: 1. A Diagram, by John Gough, Esq. to . illustrate the Doctrine of Mixed Gases; 2. A very simple Scale for Drawing the Vanishing Lines in Perspective, by G. Cumberland, Esq.; 3. Figures by Dr. Herschell, exhibiting the singular Outline of the Disk of Saturn; 4. Draw- . ings ona Quarto Plate, shewing the manner in which the Experiment of the Invisible Girl is performed. I. Description of a very simple and useful Scale, for dividing the Vanishing Lines in Perspective. In a Letter from G. Cumberland Esq. - Page 1 II. An Essay on the Theory of Mixed Gases, and the state of Water in the At- ~ mosphere. By Mr, John Gough. Communicated by Dr. Holm. _ 4 From Lp 14 IV. On Comparative Micrometer Measures, In a Letter from the Rev. Dr. ~ J. A. Hamilton, Dean of Cloyne, to the Rev. J. Brinkley, F. R. S$. From _ the Irish Transactions, Vol. X. av : Sh, at 20 Y. Observations on the Metallic Composition for the Specula of reflecting Tele- scopes, and the Manner of casting them; also a Method of communicating to them any particular Conoidal Figure; with an attempt to explain, on Scientific Principles, the Grounds of each -Process: and occasional Remarks on the Construction of Telescopes. By the Rev. James Little. From the Irish Transactions, Vol.X. —- - - - 30 VI. On the inverted Action of the Alburnous Vessels of Trees. _By Thomas Andrew Knight, Esq. F. R. S. - - = - 62 VU. The Invisible Lady, being an Explanation of the Manner in which the Ex- periment exhibited in London, by M. Charles and others, is performed. In a Letter from a Correspondent. - = . 5 69 VII. Mr. William Russel of Newman-street has offered Proposals for publishing by Subscription, Two Engravings of the Moon in Plano. By the late John Russel, Esq. R. A. - - - - - 71 TX, Letter of Enquiry from a Correspondent, whether the Light and Heat Company is intitled to Public Encouragement. - 3 73 X. Observations of Dr. Carradon, shewing that Water is not deprived of III. On the comparative Culture of Turnips. By Mr. William Watson. the Society of Arts, Vol. XXII. - ~ - 7” its Oxigen by boiling. - - tap es ee XL. Scientific News, Royal Society. - - y 2. T9eFS .. FEBRUARY CONTENTS. v FEBRUARY, 1807. Engravings of the following Objects: 1. An expanding Wheel for driving Ma- aed. by Mr. Flint; oA new Door Latch, by Mr. Antis; 3. An improved Book Case Bolt, by Mr. Herbert; 4. An Expansion Balance invented by Mr. Hardy. I Account of a Fact, not hitherto observed, that the Galvanic Power heats Water while decomposing it in Part. Ina Letter from Mr. John Tatum, Jun. 81 ‘I. Account of the Discovery of the Means of illuminating by the Gas from ~» Coal, by Dr. Clayton, previous to the Year 1664. In a Letter from Mr. John Webster. - - = = - 83 Ail. Observations on the Metallic Composition of the Specula of reflecting Tele- - scopes, and the Manner of casting them; also a Method of communicating to them any particular Conoidal Figure; with an Attempt to explain, on ‘Scientific Principles, the Grounds of each Process, and occasional Remarks on the Construction of Telescopes. By the Rev. J. Little, - 84 IV. On the Absorption of Electric Light by different-Bodies, and some of their _ Habitudes with respect to Electricity. In a Letter from Mr. William Skrim- shire, Jun. - - - - - - 101 V. Observations upon the Marine Barometer, made during the Examination of _ the Coasts of New Holland and New South Wales, in the Years 1801 » 1802, and 1803, By Matthew Flinders, Esq. 7 = = 107 VI. Letter from a Correspondent, on the Exhibition of the Invisible Girl. 119 VII. Description of a new permanent Compensation-Balance for a Time-keeper. By Mr. W. Hardy. - - - Can - 120 VIII. Description of an expanding Band Wheel to regulate the Velocity of Machinery. By Mr. Andrew Flint. oe] - - 126 IX. Account of a Discovery of Native Minium. Ina Letter from J. Smithson, Esq. F. R. S. to the Right Hon. Sir Joseph Banks, K. B. P. R.S. 127 _X. Account of a new semi-metallic Substance, called Menacane, and its Ores. By the late G. Mitchell, M. B - - = - 12$ XI. On the Cultivation of Grapes. By G. Cumberland, Esq. — - 140 XII. Useful Notes and Observations respecting the Islands of Orkney and Shet- ~dand. By Patrick Neil, A.M. - - - - 145 XIII. Description of a very useful Bolt for Bookcase Doors. By Mr. P. Herbert. 154 XIV. Description of an improved Door Latch, By Mr. John Antis. 155 XY. Scientific News:—Method of preventing Wet from being introduced into Rooms by Windows which shut together like folding Doors, 156—Extempo- raneous Printing Press, used by Country Comedians, 157-—Art of Printing from Designs upon the Surface of Stoné, 158—Gilding by Means of Zinc, 159—Clock of the famous John Harrison, which does not require cleaning. 159 —To Correspondents, 160. MARCH. vi CONTENTS. ‘MARCH, 1807. Engravings of the following Objects: !. A Calorimeter, by Montgolfier for measuring the relative [ffeets of Fuel; 2, Apparatus used in the Manufactory _of forged Iron. Vessels. I. Experiments on Palm-Oil, by John Bostock, M.D. Communicated by the Author. . = = = = - 161 IL. Description and Use of a Calorimeter, or Apparatus for determining the Degree of Heat, as well as the Economy attending the Use of various Kinds of Fuel. By M. Montgoltier. - - - - 167 Hl. Letter from Mr. Hume, ef Long Acre, respecting the Carburetted Hidrogen Gas procured from Coals, by Dr. Clayton, early in the last Century. 170 IV. Curious Observations on the Wind, by Roger Asham. In a Letter from a a Correspondent. - . - - - 171. V. Observations on the Marine Barometer, made during the Examination of the Coasts of New Holland, and New South Wales, in the Years 1801, 1802, and 1§03. By Matthew Flinders. - - - 173 VI. Analysis of the Substance known by the Name of Turquois. By M. Bouillon La Grange. - - - - SrrrcUlga VIE. Account of Mr. Curwen’s Method of Feeding Cows, during the Winter ‘Season, with a View to provide Poor Persons and Children with Milk at that ‘Time. - - - 190 VIII. Some Account of the Manufacture of Forged Iron Vessels, at Fromont. By M. C. Hersart. - - - - Fe 196 IX. Description of an Astronomical Circle, and some Remarks on the Construc- tion of Circular Instruments. By John Pond, Esq... 5 200. X. On the Utility of the Lichen of Iceland as Food. By Professor Proust. 2 10 XI. On the breeding and feeding Game Cocks. | By Sir John Sinclair. Li XII. Observations on the Culture, Properties, and comparative Strength of Hemp, and other Vegetable Fibres, the Growth of the East Indies. . By Dr. William Roxburgh. - - - - 223 XIN. Some Account of a very Singular and Important Alum Mine near Glasgow. - - - J a f 232 X1V. Method of Weaving Cloth of a surprisingly fine Quality. By Mr. William _ Neven. 235 XY. Extract of a Letter from Mr. H. Steinhauer. - - cet XVI. Letter to the Editor, concerning the Blacking for Leather. — - 237 XVIFf. Scientific News:—Astronomy, 239—Beavers in Westphalia, ib,—Letter from the Rey. Peter Roberts, A.M, ib. APRIL. CONTENTS — vii’ APRIL, 1807. Engravings of the following Subjects: 1. An Astronomical’ Circle, by Tr . ton; 2. A Drag, for raising the Bodies of drowning Persons from the Water ; 3. Diagram of anew Method of adjusting the ‘Transit cata Communi- cated by Sir H. C. Englefield, Bart. M. P. F.R.S._& L On the Inflammable mi formed corn the Dissiiaban: of Peat. By Thomas Thomson, M.D. F. R. S. E. ani be Bal II. Observations on Professor Leslie's phe of Caloric. ey Dr. Halliday, of Halesworth. - - - - 270 Hil. Description of a Drag for raising the Bodies of Persons who have sunk under Water. By Dr. Cogan of Bath. - - he Lak OTS Iv. Arguments against the Volcanic Origin of Basalt, derived from its Arrange- ment in the County of Antrim, and from other Facts observed in that Country. By the Rev. William Richardson, late Fellow of Trinity College, Dublin. 27T ¥V. Method of adjusting a Transit Instrument in a Plane of the Merdiani By ‘Sir H.C. Englefield, “Bart. M.P. F. R.S. &c. - - 291 p VI. Observations on the Variation, and on the Dip of the Magnetic Needle, made at the Apartments of the Royal Society, between the Years 1786 and 1805 inclusive. By Mr. George Gilpin. - > - 294 VII. A few Remarks on a Pamphlet entitled “ Mr. W. Nicholsen’s Attack, in his Philosophical Journal, on Mr. Winsor and the Natioeas Light and Heat ‘Company, with Mr, Winsor’s Defence.” - - 308 VIII. Account of the Small Whales in the Seas near the Shetland Isles. By Patrick Neill, A. M. Secretary tothe Natural History Society at Edin. 310 TX. Method of preparing Pannels for Painters. By Mr.S.Grandi. - 316 X. Scientific News: Small Portable Fire Engine, 318—Enquiry respecting Grease Spots, ib—-To Correspondents, 320. MAY. viii CONTENTS. MAY, 1807. Engravings of the following Subjects :. 1. Apparatus for heating Rooms by Steam. By Mr. N. Snodgrass; 2. A new Instrument called the Astrometer. By Mr. Brewster; 3. Improved Pneumatic Apparatus. By Mr. Austin. I. Description of a New Astrometer for finding the Rising and Setting of the Daye and Planets, and their Positions in the Heavens. By David Brewster, .M. ee - - - - - 320 Il. Questions and Remarks concerning the best Methods of destroying: the In- sects which infest Dwellings and Furniture. By a Correspondent. 324 III. Account of the Method and Advantage of heating Apartments and Manu- . factories by Steam. By Mr. Neil Snodgrass. - - 326 IV. Experimental Inquiry into the Nature of Gouty and Gravelley Concretions. By Thomas Egan, M.D. F. R. S. - - - 335 V. An Essay, Phisiological and Experimental, on the Effects of Opium on the living System. By William Alexander, M, D. > - 346 VI. On the Methods of improving Poor Soils, where Manure cannot be had. By John Alderson, M. D. - - - - 360 VII. Description of- an Apparatus for transferring Gasses . over Water or Mercury, &c. By the Rev. Gilbert Ausein, M. R.I. A. - 377 VIIL. Description ef the Mineral Bason in the Counties of Monmouth, Gla- morgan,-Brecon, Garmarthen, and Pembroke. By Mr. Edward Martin. 381 EX. On the Water Pits of the Glaciers of Chamouny. By a Correspondent. 383 — X. Remark by M. De Lalande on the Distance of the Stars. = 386 XI. Observations on the Soda, Magnesia, and Lime, contained in Water of the Ocean; shewing that they operate advantageously there by neutralizing Acids, and among others the Sceptic Acids, and that Sea Water may be rendered fit for washing Clothes without the. Aid of Soap. By Samuel L. Mitchell, of New York. - - . - 387 JOURNAL : OF NATURAL PHILOSOPHY, CHEMISTRY AND 2 EE, AR ETS: JANUARY, 1807. ARTICLE 'f. “Description of a very simple and useful Scale, for dividing the Vanishing Lines in Perspective. Ina Letter fron G.Cum- , BERLAND, Esq. ) To Mr. NICHOLSON. SIR, 44:3 Wee . A VARIETY of occupations and speculations have of late Introduction. forced me to neglect some former engagements, to use my poor endeavours in promoting the laudable ends of your truly inte- resting publication. But that I may not be thought to have entirely forgot them, I send you the following trifle, ess however simple the idea, will, Iam sure, be the more valued by you on that very ac- account, it I have justly estimated the noble seapoStR a your intelligent mind. ! Having been in the habit of drawing for my amusement all The valuable my life, and feeling the value of that acquirement, it has been al of Perspec- my practice to recommend to others as much of that acquisi- tion as can. with very little trouble be attained; I mean the putting into perspective common objects; such as simple landscapes, machines, buildings, and the interior of apartments, manufactories, 8c. And where I have had an opportunity to Vor, XVI.—Jan. 1807,—No. 65, B ate 4 PERSPECTIVE DRAWING.- May be very give four or five close lessons, I have generally seen my end easily acquired Obtained to their great satisfaction, without ever shewing thenr the Jesutts, or any other voluminous treatise ; books that have hindered more from the study of art, than they have ever made artists; for amoment’s consideration on this subject will convince any mind, capable of reflection, that, to accomplish the general ends that even most painters have in view with respect to that art, itis only necessary to know the use of the points of Hewhocan put sight-and horizontal line. For while men have agreed to avoid horizontal and evel lings in all their constructions that are intended for use or Pee e rig per- babilation, we shall only want h knowledge of the art lines into per- habitation, we shall only want as much knowledge of the a spective, will as will enable us to. put these into perspective, and to assit us soon be able to th = do every thing @t first, before, by practice, we have attained a correct eyes reaseh oe for practice, daily practice, will soon do all the rest, even by barely drawing the interior of a large apartment or gallery, with the objects continually before usin common use. Simple contri- To gave time, however, and to imprint the few lessons ne- vance for Va- r 5 ; 5 nishing-Lines. Cessary to be given on’ the mind ofa learner, I have, some time | 93 back, made use of the following simple contrivance, which I ‘now send to you, as the most likely means of universally pro- moting this necessary preliminary study, where the first gene- It isa ruled pa- ral principles have been instilled :—Take a sheet of paper of A having the an octavo size, and rule it with very/black ink, from A to B. nes thereon. ; : é (Fig. 1, Plate 1). This represents the horizontal line; then fix a point in the centre, at C ;. this we will call the moveable point of sight: afterwards cross it, as in the plate, with as many diagonal lines as you please; and thus you have an in- strument prepared that will be a sure guide to an inexperienced eye, in taking the perspective lines of all objects placed at right angles; such as streets, buildings, churches, apartments, &c. by mearly placing it under the leaf you mean to draw them on from nature, so as to see them faintly through, as boys do their writing-coptes, when young and inexperienced. A correspond- But, to make this instrument more complete, we should add french hl a plate of glass of the same size as the leaf of the drawing- milgr lines... book, on which the like dark lines should be drawn so as, by ‘holding it up perpendicularly, we may see, and, as it were, render tangible, the truth of perspective lines of buildings; and for those whose sight is bad, or for very young people, it would —or a copper- not be amiss to take a copper-plate of the like dimensions, and . plate, or print-\.. sents . 7 I f BP ict lence with a fine needle gently scratch out the like iimes, in which aes a PERSPECTIVE DRAWING. ease there will be no necessity to take off the burrs, as the en- ravers call the ridges raised in ploughing copper; and, from this plate, ‘en thousand impressions may be taken of the faint lines, by way of guide, on the drawing-book of a young begin- her, without injuring the plate; for I can assure your readers, Utility of en- that it is more difficult to erase a slight scratch from a sharp Tighe piele needle on copper, by the act of cakitie impressions, than ‘the deepest cut of the graver; the reason of which is, that the ridges of the skin of the printet’s hand can never enter that fine fine, whereas, in a coarse one, he polishes the edges of it down by every operation, and thus renders it a smooth channel, at last undefined, and incapable of retaining the printing ink; and the reason Lam. so diffuse on the subject is, that I think the knowledge of‘ it may be generally useful, particularly to those — patticularly who wish to extend the publication of botanical outlines: as it” aul is not necessary to be taught the art of engraving for those who ‘can draw lines; to.design, on copper the peculiarities, of plants, or their anatomy. How to trace deeper lines with certainty on copper as easily as on paper, I will have the pleasure to com- municate to you at my next leisure moment. cata ie mulote oye ene we may adda sheet of perpen- Sheet for per- dicular lines, by. which means the uprights will all be shewn ; ere and for very heavy, intellects, at first even the horizontal scale might be useful, though I never found it so among my acquaint- ance; There are also-many little helps of simple contrivances to further the first acquirement, of this plain branch of the art ; that, if you approve the idea, I shall with pleasure transfer from my portfolio: but, with respect, to the applic ation of this already described, it will be necessary,to permise, that the scale should be longer. than the drawing-book each way; by which means, by barely, sliding it.to lis right) or left, you can at pleasure place your point,of sight more or less to the right, or left, or “middle of the horizon; and,.to be prepared for all, circum stances, it would beas well to be provided also with a scale having a high horizon, and another with a very low one, such as the Dutch painters generally used, and which ever produces a picturesque effect, by giving many profiles of the elevations, and multiplying the lines of lights, Ble a Thus you have an easy expedient for a first help—practice practice will will accomplish the.rest; for we all know, or should know, oe the B 2 ~~ 4 ON. MIXED GASES. that daily practice discloses to the industrious draftsman all the arcana of optical, aeveal, ard linear perspective, destitute, it is. true, of terms to describe his acquirement; but to his own mind: a perfectly intelligible and useful rule, by the help of which he can, with certainty, imitate all he sees onthe theatre of the universe. With respeet and esteem, EI am, Sir, Your obliged humble Servant, Bristol, Dec. 4. 1806. G. CUMBERLAND, i a TORS An Essay on the .Theory of mixed Gases, and the State of Water in the Atmosphere. By Mr. Youn Goucnu. Com- municated by Dr. Hoime.. ae hcg ws Four essays appear in the fifth. volume of the Memoirs of verted to, the Literary and Philosophical Society of Manchester, which contain many new ideas relating to the constitution of mixed. gases, and the sate of water in the atmosphere. The design ef these papers is evidently intended to remove certain. diffi- culties which must strike every man of science, who happens to peruse M. de Lue’s Theory of atmospherical Vapour. This attempt has the double recommendation of ingenuity and novelty ; but the leading opinions of the system, even in its: present form, are lable to several objections, which 1 am going to point out, being generously invited to undertake the task, by the author himself. My doubts relative'to the sub- _ ject arise partly from. mathematical considerations, and in part from the evidence of experiment. Certain: objections of the first class dispose me-to conclude, that an atmosphere construc- ted on Mr. Dalton’s plan, will appear upon examination to be sepugnant to the principles of the mechanical phylosophy ; and a direct appeal to experiment has moreover convinced me,. that well established faets contradict the essential points of the theory.. Concise view 10 begin with the objections of the former class: T am of Mr. Dalton’s ready to admit the existence of a fluid mixture, such as we find. pee cde MiX- described at page 543, in the* fifth volume of the Manchester * See our Journal, Vol, VJ, p. 257. ON MIXED GASES. 5. Memoirs, with this reservation, that the concession is made, fyamination of merely for the purpose of shewing such a combination to be Mr. Dalton’s incompatib'e with the usal course of things, for a moment ; oe et which being demonstrated, the inutility of the fundamental _ hypothesis will follow, as a necessary consequence.+To give a concise view of Mr. Dalton’s general notion of the subject, ‘we are to suppose a number of distinct gases to be confined in a space common to them all; which space may be circum- scribed by the concave surface of 2 vessel, or the compressing power of an external fluid: besides this, we must imagine the constituent particles of each andividuel gas to be actuated by a mutual repulsion, while, at the sametime, they remain per- fectly indifferent to the particles which compose the other fluids that are confined in the common space; in short, we are to conceive, that the particles ofeach gas act upen those of their own kind in the manner of elastic bodies; but that they obey the laws of inelastic bodies, as eften as they interfere with corpuscles of a different denomination. After premising the preceding particulars, we may conceive a certain arrangement of the elementary parts of a fuid mixture, in which the ad- justement of the whole shali be of description which wil ” form, from particles of any one denomination, a homogeneous fluid, possessing its own separate equilibrium ; consequently, éech gas will exist as an independant being, and exercise the fanctions of its elasticity, just as if all the other fluids were withdrawn from the common space. This systematic arran- gement in an assemblage of gaseous substances cannot be maintained, unless one particular method of disposing its com- ponent parts be observed ; wich consists in that distribution of the elements which will produce a separate equilibrium in the fluid composed by the elementary corpuscles of each denomi- mation , consequently, the equilibrium in question cannot take place unles the necessary disposition of the heterogeneous particles be first established ; so that the former requisite of the theory is entirely depended on the latter.—-After having ace quired a distinct idea of a fluid mixture, composed of gases possessing separate equilibria, we come in the next place to investigate the mechanical properties of such a compound ; in ihe prosecution of which enquiry, the comparative densities of the constituent fluids must be first determined ina horizon- tal plane, the situation of which is given in the common space, B3 6 Examination of Mr. Dalton’s theory of mix- ed gases, ON MIXED °GASES.* Let the figure P- MI N.K V, Plate 1, Fig. 2, represent this space, in which M V N K is the given plane.—Now since every point of this plane may be supposed to be at an equal distance from the ¢arth’s centre, the density of every homoge- neous gas supported by it, »will be the: same in all parts of it. Let the constituent fluids be denominated:A and B; alsolet C denote the compound ; moreover let the densities of A and B, at P, bepandq; let P X and X Y be two equal evanescent parts of the line PV. . Now seeing the pressure acting upon an elastic fluid is as the density of it, the fluxionarie increments of p and q, are as these quantities; but the densities of A and B, in the point X, are equal to the sums of p and qg united to their increments respectively ; let these sums be called e and JF; then eis tofas p is to g, by composition of proportion: in like manner we. find the density of A at Y to be to that of B at the same point aseis tof; i. e. as pis to g 5 thence it follows that the fluxionary increments of the two densities have uni- versally the givin ratio of pto.g; consequently the centempo- rary fluents, or the densities themselves have the same given ratio: now what has been proved of the two-gases A and Bmay be extended.to any other numbers, viz. the ratios of. hein densities, on the same horizontal plane will be given, The ratio of A.B; &c. being found te be constant, we can) proceed to investigate the proportions of the quantities of mats. ter contained in these fluids: Let D and.d be the densities of A and B, in the plane MKNV;; also let W and w be the quan- . tities of matter of each kind, contained in the variable space PMKNV; call PV 2, andthe area of the plane MKNV y: now the fuxion of the space PMKN.V .is exprssed by y into. the fluxion cf x; moreover, the quantities of matter, in two solids are in the complicate ratios of their magnitudes and den- sities, or inthat of their densities only; if their magnitudes be equal; therefore the fluxion of W is to that, of w as Dei is to ds because the fluxionary magnitude is_ common both to W and ; bat Dis to das p to q,.a constant ratios. consequently fasion of W is to fluxion of w as p is to q; therefore, W has to. w, the same given ratio ; that 1 is, the matter in Ais to the mat-. ter in Bas pis to, gq; In the next, place, let R and r be the. distances of the centres of gravity of A and B, from the point P, taken i in the line PI: then R into the fluxion of W. i is, equal to the. product, ¢ of D, Y,.% and the fluxion of a, from a swell, ON MIXED GASES. 7 known theorem in mechanics; for the same reason, 7 into the Bodie onat fluxion of w is equal to the product of d, y, x and fluxion «; hence R into fluxion of W is to r into fluxion of w, as D isto d3 but D is to d, as fluxion W is to fluxionw; therefore R and x are equal: consequently the centres of gravity of A and B coincide, and the point of their coincidence is also the centre of the sytem C. Thus it appears, that when the component gases of a fluid mixture possess separate equilbria, their densi- ties are every where ina givenratio; and they have a com- mon centre of gravity; the converse of which is equally true, viz. if their. densities be not every where in a given ratio, and if they have not a common centre of gravity, they do not possess separate equilibria. “It is necessary to observe, in this stage ef the inquiry, that though we admit the particles of A and B to be inelastic in relation to each other, the concession must be strictly confined to the particles themselves ; for the gases which are composed of them are elastic bodies: they therefore receive and communi- eate motion according to the laws which are peculiar to bodies of this description. The foregoing properties of a fluid mix- ture, which has been supposed to be duly adjusted, is now to be used in the examination of the fundamental proposition of the new theory intended to explain the constitution of the atmosphere. According to this proposition, if two gases come into contact, the particles of which are ‘perfectly inelastic in respect of each other, the particles of A meeting with no re- pulsion from those of B, further than that repulsion, which, as obstacles in the way they may exert, would instantly recede from each other as far as possible in their circumstances, and consequently arrange themselves just as in a void space. The precedingare the words of the author of the Theory; and it is readily granted that the particles of such a heteregeneous mix- ture would recede from each other as far-as circumstances will permit; the present subject of inquiry then brings the dispute to this issue—can that arrangement take place amongst the “particles of two or more gases, which will make their centres of gravity coincide in one point? For the separate equilibria of the fluids, which enter into the constitution of the com- pound, will not be established until this arrangement be per- fectly formed. The completion of this process being essential to the new theory, the effect of it has been, perhaps, too Mr. Dalton’s theory of mixe, ed gases. 8 ON MIXED GASES. ~ Examination of hastily inferred in the fourth proposition of Mr. Dalton’s first Mr. Dalton’s theory of mix- éd gascs. essay; for I am sorry to ohserve, that the inference is not supported by demonstration, drawn from the doctrine of me- chanics. Itis the business of the present essay to supply what has been omitted, and to investigate the consequences which must arise from the collision of two heterogeneous gases, differing in their specific gravities. The existence of the fluid mixture, required by the theory, has been granted already, for the sake of argument; and in order to continue the inquiry, it must be remarked at present, that the necessary internal arrangement of the com. pound C, is liable to be disturbed perpetually by accidents resulting from the course of things; to which course the author of the theory undoubtedly wishes to accommodate his ideas. ~ The preceding assertion may be exemplified in a manner which is familiar, and may be applied with ease to natural phenomena: let us suppose then an additional quantity of the gas A to be thrown into the pneumatic apparatus, containing the compound C, which was in a state of proper adjustment previous to this event. No one will imagine, that this fresh matter can diffuse itself through the mass of C with the same expedition that the electric fluid shews in expanding along a conductor: this supposition is contradicted by various appear- ances, from which the following one is selected ; agitation is known to accelerate the union of oxigen and nitrous gas. The quantity of A then, which has been newly admitted, will re- main at first unmixed with B; but it will act immediately with a repulsive force upon kindred particles diffused through the compound C. This new modification of A will not preserve the density of its parts every where in a constant ratio, ta the density of the corresponding parts of B; and this change will disjoin the centres of gravity of A and B; which has been proved above. But when these points are placed apart, the separate equilibria of the fluids cease to exist, which has also been demonstrated before; therefore A and B begin to act and react mutually ; which circumstance disturbs the necessary ° adjustment of C, and forces it to assume another’ character. It has also been proved in a former paragraph, that the two fluids will act upon each other in the manner of elastic bodies, even when the heterogeneous particles are supposed to-be mu- tually inelastic ; consequently A and B will begin to obey the @N MIXED GASES. | eS Jaw of their specific gravities, as soon as their centres Of gra- Eyaminationof vity are separated by introducing into the space occupied by a rae C, a fresh quantity of A or B: in consequence of this altera- perigee tion the centre of gravity of the heavier fluid will begin to de- scend while that of the lighter moves upwards. When once the centres of two gases are placed apart, their separation will _ become permanent; because, when at a distance, they are urged in opposite directions by a force resulting from the dif- ference of the specific weights of the two fluids; and this con- - trariety of efforts must continue so long as the two centres are disjoined ,; consequently this opposition of force must be last- ing ; seeing nothing can put an end to it but an union, which it will always prevent. Nor can the mutual repulsion of the constituent particles of each gas, considered apart, in any man- ner promote the junction of the centres of gravity of the two fluids; because the action and reaction of a number of bodies amongst themselves do not alter the state of their common centre of gravity, whether it be at rest or in motion: so that A and B are under the necessity of observing the law of their specific gravities, just as if the kindred particles of each fluid were actuated by no reciprocal repulsion nor any other cause of reaction. The doctrine of gases, which are mutually ine- lastic, is rendered indefensible by the preceding arguments; for the hypothesis is thereby exposed to a difficulty which the author of the theory justly remarks, makes a mixture of mu- tually repulsive gases of different specific gravities an impro- bable conjecture; so that his own objection ultimately dise countenances the leading opinions of that theory which it in- duced him to adopt in particular. At the same time, philoso- phers are convinced that the atmosphere is a compound of gases, possessing various degrees of specific weight: they moreover know, that different chemical agents perpetually dis- turb the equilibrium of the compound, as some of them con- stantly absorb while others unfold the gases of which it is com- posed. The preceding facts are certain: consequently the heterogeneous elements of the atmosphere must be united by a common tie, which may be denominated a species of affinity, at least while our knowledge of the subject remains in its pre- sent imperfect state. The transparency of the great body of air surrounding the earth, also affords a strong argument for ’ the chemical union of its component fluids; and, at the same 10 ON MIXED: GASES. Examinaticn of time, discountenances the idea of the compound being a me~ Mr. Dalton’s theory of ‘mix- ed gases. chanical mixture of any description whatever; for when a number of diaphanous bodies of different specific grawities are raixed together, they form an aggregate which is opaque ; but the union of the substances by fusion renders the mass . transparent in many instances. Now as the atmosphere is diaphanous, we are obliged, by the principles of sound argu- nent, to consider it in the light of a compound, the ingredients of which are united by a chemical tie.—Whatever may be the condition of the elastic fluids which enter into the composition of common air, one thing is certain froma preceding para- graph of this Essay ; namely, no on@of them can maintain a separate equilibrium as long as it makes an individual of the aggregate; consequently, each particle of the compound must be urged by a force resulting from the general action of the mass, not by a pressure occasioned by a particular member of if. On this account, it is impossible for the acqueous part of eommon air to preserve the character of a gas at low tempe- ratures; because steam cannot support 30 inches of mercury unless it is heated to 212 degrees of Farenheit’s thermometer ; were it then practicable to' mix vapour of a less heat with at- mospherical air, the spring of the gases would reduce it in an mstant to the state of a liquid; so that the difficulty, which renders De Luc’s theory objectionable in its original form, is not removed in reality by the present modification of it. . The theory of mixed gases has been found to be indefen- sible on the principles of the mechanical philosophy; and I suspect that part of it which relates to the separate existence of vapour in the atmosphere, will prove equally unfortunate when brought to the test of experiment. Mr. Dalton, in all probahility, supposed he had done all that the confirmation of this theory required, by inventing the doctrine of separate equilibria, for nothing more has been offered in support of his opinions, particularly of that relating to the existence of un- combined vapour pervading the atmosphere,, unless the state- ment of the following experiment, with his explanation of it, may be referred to this head. If two parcels of dry air, which are equal in bulk, density and temperature, be confined by equal columns of mercury, in two tubes of equal bores, one of _ which is wet and the other dry; the air, which is thus ex+ ON MIXED GASES. posed to water, will expand more than that which is kept dry, Examination of provided the corresponding augmentations of their tempera- tures be equal; which phenomenon is thus explained on the principles of the theory. The vapour that arises from thé sides of the wet tube, possesses a spring of its own; therefore- it takes off part of the weight of the mercury from the air, and thereby leaves it to expand itself, so as to re-adjust the equi- librium. ‘According to this explanation, if 7 and g represent the length of the columns of dry and moist air. at any tempe-. rature; and ifc denote the length of a column of mercury, equal in weight to the pressure that confines the contents of the tubes; and if f be put for the spring of vapour of the same temperature measured by a column of mercury, we have le : ; “fe - ¢==—— from which we also get c= c—f; : g—l the last expression affords us an opportunity of comparing the preceding explanation, and therefore the theory itself with facts; for, according to the experiments of Mr. Schmidt, 1000 parts of dry air at 32 degrees of Farenheit, will expand to 1087,11 parts, by being raised to 59 degrees, in contact with water; call this Mi ciedae according to the same author, 1000 parts of dry air at 32 degrees will expand to 1053,61 parts, by being heated to 59 degrees in a dry tube; let this number be 7; then g—/ = 33.50: but f, or the spring of vapour at 59 de grees, is .507, according to Mr. Dalton; then Goo l,16e;. Nence.c — 16,19 pay ae which expresses the height of the barometer, together with the column of mer- cury contained in the tube. If the temperature be stated at 95 degrees, c will amount to little more than 8 inches: now it is highly improbable that Mr. Schmidt made his experiments when the barometer stood at a height indicated by either of these numbers.—This application of the theory to practice, affords a presumptive evidence that the principles of it are not altogether just, supposing the experiments of Mr. Dalton and Mr. Schmidt to’ be correct : but a positive ‘proof of a want of accuracy in these’ principles may be obtained by introducing a small change into the ‘manner of conducting the experiment made with moist air. This alteration consists m discarding the stopple of mercury, and substituting the simple pressure of the. Mr. Dalton’s theory of mixe ed gases. 12 ON MIXED GASES. Bxamination of atmosphere in the room of it: because when this substance, Mr. Dalton’s theory of mix- @d gases. which is impenetrable to steam, has been removed, the redun- dant vapour will, according to the theory, flow into the at- mosphere, thereby leaving the moist air of the tube to follow the law of expansion observed by dry air. With a view to find whether this be the case or not, | filled a bottle with run- ning water of the temperature of 59 degrees, which, when carefully poured out again, weighed 7794 grains. .The bottle, having a dew left sticking to the sides of it, was placed in water at the temperature of 126 degrees: the mouth, which remained about an inch above the surface, was covered with my hand, care being taken to remove it frequently for an imstant to permit the vapour and expanding air to escape. After keeping if in this situation about two minutes, I secured the mouth in the manner described above, and inverted it in a quantity of the same water, where it was reduced to 59 degrees; in consequence of which it. took up 1622 grains of water, leaving a space equivalent to 6172 grains. If the ex- periment be now inverted, 6172 parts of air will oceupy the space of 7794 such parts when its temperature is raised from 59 to 126 degrees; which is nearly double the expansion of , dry air in like circumstances, For, according to Mr. Schmidt’s experiments, 1000 parts of dry air of 59 degrees will become equal to 1133,03 such parts, by being heated to 126 degrees; therefore, by the rule of proportion, if 1000 parts give an ex- pansion of 1133,03 such parts, 6172 parts give oniy 820: but the difference of 7794 and 6172 is 1622, which is nearly the double of 820. The preceding experiment, and others which I have made of the same kind, demonstrate that moist air ex- pends more than dry air under like circumstances; and the fact subverts the notion of uncombined elastic vapour mixing with the atmosphere. The accuracy of the fact may be dis- puted; the doubt however is removed by repeating the expe- riment: but so long as my statement remains uncontradicted, the consequences of it to the theory in question, cannot be controverted by argument: for if elastic vapour, mix with the air, it does more than merely enter the pores of this fluid; for, according to my experiment, it enlarges these pores at: low temperatures, which we know to be impossible, unless the heat of the compound arises to 212 degrees. Those who are ON MIXED GASES. “13 “sonvinced of the superior expansion of moist air, will readily Bestatabien of apply the principle to certain interesting phenomena, in par- Mr. Dalton’s ticular to the origin of Tornadoes in hot countries, and the pepe kt Variation of the barometer in temperate climates. Mr. Barrow, an intelligent traveller in South Africa, ob- serves, that the atmosphere in Caffraria is sometimes heated to 102 or 104 degrees: this is succeeded by local thunder storm, attended with heavy falls of rain and hail, as well as violent hurricanes. I do not pretend to assign the refrigerating cause, or the agent that produces precipitation in this case ; T only have to observe, that the portion of air must lose much of its elasticity, which is suddenly cooled to 70 or 72 de- grees, and at the same time parts with the water it held in solution. This partial diminution of spring will destroy the equilibrium of the adjacent parts of the atmosphere, and may be supposed to produce the tornadoes of the tropical regions. The same cause probably gives rise to the fluctuations of the barometer in milder climates; for though the changes of tem- _ perature are less in the milder than in the hottest parts of the globe, the agents that precipitate the water, of the atmosphere, #ppear to act on a more extensive scale, and through a longer duration in the former situations than they do in the latter. Wet weather is neither momentary nor local in Europe; pre- vinces, and éven kingdoms are deluged with rain for weeks together. The air, which discharges such an abundance of water, will lose part of its spring, according to Mr. Schmidt’s experiments, even when it suffers no change of temperature: now it is evident that the equilibrium cannot be restored in an instant; because the diminished elasticity must be augmented in this case by currents of air coming from remote places. The diminution of spring in the atmesphere is shewn by the fall of the barometer ; and the subsequent ascent of the mercury indi- _ €ates the arrival of the restorative currents. According to this explanation, the barometer will rise slowly but gradually in the centre of the rainy distri ict, while the motions of it will be more rapid and less regular towards the verge of the storm. High winds will also prevail in wet seasens, arhiel will blow 5 aM the parts where the elastic force vf the air is least; that is, where the rains are most abundant.—I know not what @laim to originality is due to the foregoing hints towards the 14 Culture of Tur- neps. TUR NEPS« theory of the barometer; they have, however, the merit of being a.natural consequence of an established fact; I mean the great dilatation of air saturated with moisture, which must undergo a proportionate contraction when deprived of water,’ On the comparative Culture of. Turnips. By Mr. Wiliam Watson*. Havine been long, and pretty extensively employed in Agriculture, in a district where the turnip husbandry is ‘much practised, and being satisfied that when the soil is proper, and the management Fen great crops of that invaluable root are the most profitable means of obtaining luxuriant and pro- ductive crops of corn, &c. and of laying a solid foundation for future abundance in the increasing quantity of manure, I have paid particular attention to the different modes pursued in its cultivation. It is with great pleasure, therefore, that in the list of premiums offered by the Society, instituted at Lon- don, for the Encouragement of Art, &c.—a Society whose patriotic and laudable exertions deserve the most warm and grateful thanks of every real friend to the British empire,—I observe one for the best set of experiments made with a view of ascertaining the most. advantageous of these modes ; 3; and, having tee a comparative sti with great accuracy, © I beg leave to request that you will do me the honour of laying this paper, which contains an account of it, before the Society. That there are situations in this kingdom in which eight acres of Jand may be found of an uniform quality, I do not doubt. I must, however, remark, that I never found that number of acres contiguous to each other, or Properly situated, for an accurate comparative experiment, in the fallow land of any farm in which I have been concerned, so precisely similar in soil and condition, as to induce me to think that I ‘could have exhibited the result of so extensive an experiment as irrefra- gable evidence of the superiority of any particular mode of entre: Besides I could not have attended eithet to the mi- nute mixing of the necessary quantity of dung for eight acres of ground, so as to have rendered it of an uniform quality, * Society of Arts, Vol. X XIE. TURNEPS. et) nor to the weighing of all the turnips upon that quantity of cultiviaion of land, without which, (when I adverted to the difference of t eH by Mr. William Wat weight occasioned even by a scarcely perceptible difference in .4.., the cealcters of similiar solids) I could not have totally di- ‘vested myself of some doubts as to the accuracy of the result. Fo these reasons, I could not satisfactorily conduct the ex= periment on so large a scale as that proposed by the Society ; and though 1. am thereby prevented fromm becoming a candidate for the Medal,—a reward by which I should have considered myself highly honoured,—yet I hope this Communication will not be deemed altogether unimportant; and that it will, in some degree, forward the views of so distinguished a body. Every part ‘of the ground upon which this experiment was made, had been managed fora series of years, in exactly the same manner. After being three years in‘grass, it produced a crop of oats in 18023 in the autum of which year it was once ploughed. © In May-and June following, it received thrée furrows in the common way, and was conipletely puiverized and cleaned; after which it was divided into - four flat ridges, about eight: yards broad, each ridge containing precisely 4719 square ‘feet. "The soil is. a dry, ‘light ‘sandy loam, mixed with smalf hard’ stories, incumbent ona thick. sud: stratum of gravél; and the four ridges were so much alike soil and condition, ‘that Lihink I may assert, that the most ‘accurate chemical operator could not have proved’ the smallest difference ‘in these respects.. On the 22d of June last, theridge, No.1, was manured with dung; immediately after which, the’ manure was regularly spread over it, and ploughed in.’ The whole ridge then received a single working, with a light short-tired harrow; and-while the moisture was Fresh, the turnip-seed was sown witha machine, in rows, upon a flat surface with thirteen inches intervals, About the samé hour, the ridge, No. 2, was prepared and formed into small tidges, or drills, upon which the turnip-seed was deposited in Fows, with ‘a macliine, twenty-six inches from each other. The dung in about one third of the raised drills on this ridge was partly left without being completely covered in. Early the next morning, the ridge, No. 3, was us fornved into small ridges, or drills, with intervals of twenty-six inches. On ‘the’ tops'of these ridges, ‘a proper machine quickly depo- sited the turnip-seed in single rows, pi oy in the same mode as that pursued in No.2. On this ridge, however, Ne. 16 TURNEPS. Cultivation of 3, every atom of the dung was carefully covered with the Turneps, by Mr. William Watson. plough. Immediately after No.3 was finished, No. 4 was dunged and sown with turnip-seed, in the usual manner, in the broad-cast method.—Every part of the four ridges was manured with dung of the same quality. It was not thoroughly rotten, but had arrived ata more advanced stage of putrifac- tion than that used by farmers in general ; and, in order that its quality might be uniform, it was carefully taken from one part of the fold-yard, and well turned over, and mixed in the field*. An equal quantity was applied to each ridge, at the rate of fifteen two horse cart-loads + per acre. The turnip-seed was likewise of the same quality and kind, and was sown on each ridge at the rate of about one pound and a half per acre. The succeeding weather was remarkably dry and unfavourable for the growth of the turnips, only one light shower having fallen, from the time the seed was committed to the ground, to the 16th of September following.—Notwithstanding this, however, the whole of the four ridges planted exceedingly well, though not so early as I could have wished; and their progress into the rough leaf, as well as their appearance for some time afterwards, was propitious. From the extreme se- verity of the drought, however, and the natural dryness of the land many of the plants in every ridge were killed. No. 1 lost the greatest quantity; No. 2 the next, espe- cially on those drills where ihe dung was not all completely covered in; and No. 4 scarcely so many as No. 3, — Throughout the whole crop, vegetation seemed extreme- ly languid, and the turnips were generally of a small size ; the largest were produced on Nos. 2 and 3, in the drills with intervals of 26 inches. These intervals were twice horse-< hoe. In these rows the plants were left about eleven inches asunder. Numbers 1 and 4, in which the plants were set out at about twelve inches from each other, were thrice hand- hoed with great accuracy. The several operations of plouh- ing, sowing, and hoeing, were performed in the same kind of weather on each ridge. I attended the whole of them my- self, and can safely say that the utmost precision and impartia- * Dung was the only manure applied, + The cart was five feet three inches long, three feet three inches broad, and one foot six inches high, in the inside, TURNEPS. 17 My were observed. ‘The four ridges were carefully. sur- Cultivation of « € . ; turneps, by Mr. rounded with proper rails to prevent damage, and no depreda- William Wats tions of any kind were committed *, On the first of this month, so2. all the turneps which were. produced on these ridges were drawn up, and carefully and. exactly weighed, after their tops and‘tap, or fibrous roots, had been cut off. The produce of each ridge wasasunder:— ‘ No. 1, drilled on a flat surface, stones. ibs. bs. with intervals of 13 inches 144 10-14 to the stone, No. 2, drilled on small ridges, with intervals of 26 inches, and with a part of the dung not perfectly covered in 193 5—ditto. No. 3, drilled on small ridges, with intervals of 26 inches, ‘and all the dung well covered Dera oe ek) OED a dite, sINo. 4, broad cast. . . *s. 168 12—ditto. Remarks on the different Modes of Culture. No. I. In this method of management the dung is. applied in a manner exactly similar to that practised in the broad-cast husbandry; and experienced agriculturists well know, that even after it has been thoroughly putrefied, it cannot be wholly covered by the earth in the mode of ploughing, pursued under ‘that system of cultivation. In almost all cases, the harrows are used to produce an even surface after the last ploughing, and immediately before the seed is committed to the ground. By this operation more of the dung is left upon the surface; and when it is considered that much of it is applied in a long or half-rotten state, it will readily be conceived, that a still greater quantity will be left exposed on the surface of the ground ; in which situation it can conduce but Kittle, if-any thing, to increase its fertility. * Except that a moje destroyed a few plants on three drills on 0, 1 | Vor, XVIL—Jan- 1807.—No. 65. Cc 18 Cultivation of turneps, by Mr William Wat- son. TURNEPS. Under this mode of management, the plants may be left ‘at more regular distances in hoeing than in the broad-cast method; but I am mow inclined to dispute that that operation can be performed at an expence materially, if at all, less thar among those obtained in the latter way. The plants are generally left in the rows at about twelve inches apart, so that an acre will produce about 40,200 turneps, when'the crop is 2. full one. Nos. II. and III. Some practical agriculturists, as well as chemical philoso- phers, have contended, that dung should be thoroughly putre- fied before it be applied to the soil; and others maintain, that it is more ‘beneficial to apply it in a half-rotten state. Into this dispute, Iam not, at present, inclined to enter. Let it © suffice to say, that a great majority, probably upwards of three-fourths of the farmers, in almost.all the extensive turnip districts in the kingdom, apply it either in the latter state, or before it has arrived at a much more forward stage of putre- faction; and if rotten dung (thoroughly putrefied) cannot be wholly covered in this common mode of ploughing, it is obvi- ous, asI have before remarked, that, in the other state, a still greater part must be rendered nearly useless by exposure to the solar rays, &c. Inthe management now under consi- deration, however, every atom of it may be buried, if the spreaders and ploughmen are attentive. That management is as follows: As soon as the land has been properly pulverized’ and cleaned, a double-mould board plough, drawn by two horses, is used to raise small ridges, about 12 or I4 inches high, with intervals of twenty-six inches, and the tops, of about an inch or two broad. All the drills should be equal in size. The height shouldin some measure be regulated by the quantity and state of the dung. Immediately after the smalf ridges or drills are formed, a man witha cart, drawn by one or two horses, lays a sufficient quantity of dung for three or five drills (in small heaps), in the interval, while the wheels of the cart run in the adjoining spaces. In this manner all the other intervals are manured. As soon as the-dung is _carefully spread in the bottoms of the intervals, another double- mould board plough (also drawn by two horses moving in the intervals), splits the ridges along their tops. This operation TURNEPS; 19 Sa, completely covers the whole of the dung, and reverses: the Se of tops and intervals. A roller about ten inches diameter, and whe, Wate four feet in length, drawn by one horse, is now moved along son: the ridges. , It covers two at a time, leaving the tops gene- tally about ten or twelve inches broad, in the middle of which the turnep-seed is deposited, in a rut made by the coulter of the sowing machine, which is fastened to the hinder part of the above roller by a cord about -nine feet long; the distance between each row of turnip-seed, being twenty-six inches; and if the ploughing and spreading have been properly per- formed, the dung will be nearly beneath the rows. Thus the agriculturist is not subject to the waste of any part of his ma- nure, and reaps the superior benefit of having the turnep-seed regularly sown, ina rut of a proper depth; penetrating nearly to the dung in the middle of the small ridges;—a method which seems better calculated to give to the cultivator of the field advantages similar to the rapid and vigorous vegetation promoted by the hot-bed of the garden, than perhaps any . other mode of culture. The importance of having all the dung perfectly covered, is evinced by the result of the above experiment; for, with the exception of a small part of it, in a few drills on No. II., not being perfectly covered with the soil, there was no aGateie whatever between the manage- ment of that ridge and the mode pursued on No. Il]. In dry weather, the roller is moved twice along each ridge, first to compress the soil, and next to close the rut made by the coulter of the sowing machine, to secure the turnep-seed from depredation and drought: but if the soil be so moist as to stick to the roller, it is moved only once along each drill; and some able husbandmen are of opinion, that this is the most_ advantageous mode in any state of the soil; that without the second rolling, the turnip-seed will vegetate regularly; and that, while young and tender, the plants will be beneficially sheltered by the rut of the sowing-machine in adverse weather. Some cultivators form the drills, or small ridges, with a common single plough, and in many situations they are made more straight and neat than with the double plough. With the latter, however, they may, in most situations, be suff- ciently well formed, at about half of the expence incurred by using the single plough, which does mot cover the dung better than the other.—The skuffler, an implement with three or five C2 20 TURNEPS. ce me hoes is sometimes used to clean the intervals. Some, How- Willett, Wat. ever, prefer using two small ploughs of the common form, son, four or five inchés broad at the bottom, and fastened together by screws, which increase ot diminish their distance from each other, according to the breadth of the intervals. This im- plement is drawn by one hotsé, and, by being moved once along each interval, cuts a proper quantity of earth from each side of the row afpldate ; and by proceeding’ in this manner, a ridge of earth is laid up im the middle of each interval. This niode is the best in situations where the drills are not perfectly straight. Where they are quite straight, an implement is used, which, instead of moving the earth from each side of one drill, cuts it off the inher sides of two drills; and in either method the hoeing of the intervals may be performed with equal expedition. A few weeks after these small ridges are formed in the middle of the intervats, they are generally split - by a double plough drawn by one horse, the earth being laid close against the turneps on edch side. These operations ‘not only déstroy the weeds in the intéfvals, but give to that part of the land the advantages of a bare fallowing, and, besides’ being greatly cheaper, are much more fertilizing than hand- hoeing. In this mode of cultivation the turnips attam a greater size than under the broad-cast method, or that with narrow intervals; and though the plants are generally left at about eleven inches apart in the rows, which reduces the number of dh acre, when the crop is a full one, to about 21,900, the result of the above experiment will not be sur- prising, when it is considered, that from the properties of similar solids, the weights of well-formed (spherical) turneps, are in the ratio of the cubes of their diameters, and conse- quently that one of eight inches and a half diameter will weigh nearly as mnch as three of six inches diameter each.—Nearly all the farmers in this district use their utmost endeavours to obtain turnips of a larger size, which, together with the other .Important advantages derived from it, has long induced them to prefer drilling on small ridges, with broad intervals, to any ~ other mode of culture; and within the last twenty years, it has become the aJmost universal practice in the counties of" ‘ Northumberland, Roxburgh, Berwick, and East Lothian,— an extensive and extremely well managed district; in which, L believe, the rents of land are considerably higher than in any TURNEPS. 2} other m this kingdom. ey several, the drills are not drawn at Cultivation of right angles to the ridges (I mean the common ridges of the William Wat ¥ field), but ina diagonal direction ; it having been found, that son. the seed-furrow in the succeeding spring, together with the effects of common harrowing, not only reduces the land to an even surface, but that after such management, the crops of corn are uniformly luxurient and productive, the manured parts being, in these operations, well mixed with the soil in the in- teivals. Lam satisfied, from my own practice, and pretty accurate observation on that of others, that with considerably tess manure, as weighty a crop of turneps may be obtained by this method of cultivation, as by that with narrow intervals, or in the broad-cast husbandry ; and, as it is generally difficult to raise as much dung as will manure the whole of the fallow land, at the rate of fourteen to sixteen loads an acre, this, in promoting the growth of more extensively luxuriant crops, and tucreasing the quantity of manure for those which succeed, is an invaluable advantage. Besides, in unpropitious seasons, when, under the broad-cast and ‘narrow drill system, a judicious agriculturist would not cultivate turnips on land he has not been enabled thoroughly to pulverize and clean, he would * venture to raise them where the spaces between the rows are sufficiently broad for the admission of the horse and the plough, under an idea that before their tops covered the in- tervals, (which they generally do about the beginning of Oc- tober) his ground could,be brought into.a proper state—You will no -doubt remark, that the crop I obtained even on No. III., was but scanty; and conceive, however, notwith- standing that circumstance, that the experiment satisfactorily shews the superiority of the mode of management pursued on _that ridge.—By the same mode, I obtained a crop on the Jand . surrounding that en which the experiment was made, which, . considering the.extreme dryness of the summer, and ‘that it was sown at the same late peried of the season as that upon the experiment ground, may be reckoned a very pro- .ductive one; and, as the soil was not superior in quality, it __ may be of some consequence to endeavour to account for this difference. The land marked out for the experiment, con- tained some couch and other weeds, which I wished to eradi- -cate; it therefore received a.common ploughing only a few days previous to.the seed being commited to the ground. The 22 TURNEPS, Cultivation of surrounding land had lain for a much longer time between the ‘Turneps, by Mr. William Watson. Jast ploughing and the seed-furrow, and contained more mois- ture at the time of sowing them than the other; and though this, in a humid season, would not have caused a material difference in the crops; yet, in a summer so extremely dry as the last, it was attended with important advantages. To these I may add others; for dung having last year been unu- _ sually plentiful, it was manured with about ¢wenty loads an % acre, and with dung in a very moist state; whereas, that ap- plied to the land on which the experiment was made, lost a considerable portion of its moisture by evaporation, during the time of mixing well, for the purpose of rendering all parts of it equal in quality.—Perhaps it may not be deemed unim- portant to state, that the prevailing opinion is, that very dry seasons are more unfavorable to the turnips raised on the smalk ridges (drills) than to those produced on tand with a flat sute Jace. No. IV. The same objections which have been urged against the manner of applying on No. I. may be advanced against the mode of cultivation pursued on this ridge, under which the plants cannot be left with such precision and regularity as in the drill husbandry, Expence of each mode of Culture. The management pursued on Nos. I. and IV., is less ex- pensive up to the time the plants become fit for hoeing, than that pursued on Nos. II. and lil, This saving of expence, how- ever, 1s overbalanced by the cheapness of hoeing under the latter mode, and by the advantages derived font that opera- tion being performed before the plants become too large. The general expence of hoeing broad-cast turneps, in this quarter, is about seven to ten shillings per acre, of 4840 square yards. Those in drills, with narrow intervals, will cost as much ; and when it is considered, that an acre of these contains twice as many rows as the same quantity of ground under the broad intervals, and that these intervals are quickly and efficaciously hoed with the horse and plough, it will be readily conceived that the latter mode is the least expensive upon the whole. As the turneps under this experiment did not grow uniformly, MICROMETER MEASURES. 23 some parts were much sooner fit for hoeing than others. Cultivation of The person that hoed them was sometimes not employed ae ae among them above an hour in the day ; which prevents my gon, furnishing an accurate account of the expense of hoeing each ridge. So easy is the operation of hand-hoeing the small ridges or 4rills with broad intervals, that in this quarter, it is nearly all performed by women, boys, and girls. 1f we depended on amen, as the farmers do in some other districts, we could not perfectly hoe much more than one third of our turnip crops. a Iam, Sir, i Your most obedient Servant, W. Watson. North Middleton, near Wooler, by Belford, Northumberland, Feb. 18th, 1804. “On ‘Comparative Micrometer Measures. In a Letter from _. the Rev. Dr. J. A. Hamitton, Dean of Cloyne, to the ' Rev. J. Brinwxxey, F.R. §.* , Observatory, Armach, Jan. 10, 1806. DEAR SIR, BEG leave, through you, to communicate to our Academy Three methods “the following paper, on comparative observations made with °f measuring : small angles— different kinds of micrometers ; which, I hope, may be deemed the’ wire mi- worthy their notice. It was suggested to me, so long since as Te BAG di- “in the year 1794, that a comparative view of the Gecalt of the Meee hae me measures, made under similar circumstances, of the diameters sextant. of the heavenly bodies, with the different kinds of micrometers, that are now most generally used by astronomers, might have ‘considerable use; as well in confirming the determinations of the values of the diameters, as given by former observations, as in deciding on the merits of the different instruments, and is * Trish Transactions, yol, X. Q4 ON COMPARATIVE shewing, at one. view, a'sort ‘of harmony ‘of ‘micrometers. My own opinion, on this subject,-entirely coinciding with’that ~ of the learned friend, who made this :proposal, 1 »sét »about making comparative observations of the'measures of the sun’s Description and account of the wire mi- crometer. Its scale deter- mined. diameters, as taken with the old wire micrometer, made inthe best manner, by Mr. Dolland; with ‘his divided object glass micrometer , and with a ten-inch’reflecting sextant, executed, in a very capital style indeed,by Messrs. Troughton. BeforeI :proceed to the detail of the observations, it may»be proper to premise .a short account \of:the nature and ‘adjust- ments of the several instruments, that were the subjects of this experiment. The wire micrometer, as its name denotes, measures intervals, by the separation of two moveable wires : these wires should perfectly coincide, when the index of the scale marks 0 or zero: and the quantity of the separation of the wires, made by the turning of the screw which effects it, is denoted by revolutions, and parts of revolutions, of the index, over a graduated circle, attached to the micrometer- screw ; which, in ‘this instrument, consists of fifty sub-divi- sions. ‘There are several ways of ascertaining the values of these revolutions and sub-divisions, in arcs of a great circle in ‘the heavens, The method which I adopted was ‘this; the inicroscope being fitted to an achromati¢ telescope, on an equa- torial stand, I carefully separated the wires by fifteen exact revolutions ; and then turning round the whole system, till a fixed“wire, at right angles to the measuring wires, was in a plane parallel to the equator, I measured, by the ‘sydereal clock, the time the sun’s limb, and various fixed stars took, to run along the fixed wire, from centre to centre of the.mea- suring wires. This trial was very frequently and repeatedly made; andthe stars and sun’s limb, being -all reduced-to the equator, the general result gave 121",1, for the equatérial in- terval of the fifteen revolutions. This interval, reduced to space, made each revolution of the figured head = to 2’ and 1” of measure; and, of course, each of the fifty sub-divisions = to2",42 nearly of an arch of the equator. In making the subsequent measures of the sun’s diameter, or. that. of any other celestial arc, the measure was always finished, by mov~ ing the wire in the direction in which the. fifteen revolutions were originally made, The advantage-of this micrometer is MICROMETER MEASURES. 05 principally this: that; in adjusting the telescope, and the-mi- Its scale deter- crometer ‘wires, ‘to distinct vision, no alteration is made, by mined. the difterence of ‘the conformation of the eye, or of focal dis- stance, that. suits that of the observer, im the value-of the arc to be measured. The principal defects of it are: the diffi- culty of judging accurately of bisections, or contacts -of the fine wires, by the limbs to’be measured ; and the impossibilt 'y of observing any diameter, except the one perpendicular to the equator. The object-glass micrometer is an instrument, now so fami- te a ob- liar to’every person conversant in the use of astronomical in- ea yo struments, that it is only necessary to say, that mine was made, and adapted to a triple object-glass achromatic tele- scope, of 42 inches focal distance, by Mr. Dolland, and its scale very carefully verified by himself; and that the scale is, as usual, divided into.inches, 10ths, 20ths, and vernier divi- sions: that, when it is applied, it lengthens the focal ditance of the telescope about 6 inches: thus making it 48 inches, or 4 feet focal distance. = * The advantages of this ‘species of micrometer are: the Its advantages. large scale, the fine images formed, and the facility of measur- ing diameters in every possible direction. Its imperfections are: that, to different eyes, and under different circumstances of the same eye, the lengthlof the focal-distance, that suits distinct vision, will vary ; and,’of course, ‘the quantity of the measures, given by the.scale, are liable to a small variation. The goodness of ihe telescope is, also, in.some degree, im- paired, by the application of this contrivance of a divided object-glass. ‘ 4 It should be noted, that the wire and object-glass microme- ters, were both adapted,.in their turns, to the same achromatic telescope ; ‘artdhthe comparative observations made as neap to each other, in point of time, as possible. : The diameters of the sun,‘measured by the ten-inch sextant, Ten-inch sex- were’ taken with a small achromatic telescope, magnifying tant of Trough- about twelve times, and were observed on the limb, and on the oe arch of .excess, several times alternately ;. the measures being always finished in the same direction of 'the’micrometer-screw: and the quarter of the double measure was used as the semi- diameter, with the addition of 3”; which is the known dimi- nution of the image of the sun’s semidiameter, after the reflece “9 ON CUMPARATIVE tions and refractions it undergoes in the process.. As the three kinds of micrometers, just described, are so completely different from each other, in their.construction, adjustment, and mode of mensuration, I consider them as fully sufficient to make an experiment on the probable consistency of the results which may be obtained from different good micrometers; and shall now proceed to give a detail of the actual observations. . Observations Semidiameters of©,as given of the sun’s 1794. S. Dr. ©. in the Nautical Almanack. 4. diameter. August 26, D. O. G, Mier. 2 15/. 53",835 1K gn Wire Micr. . . § 15’. 54,03 15’. 53/342. A Sept. 3, D. O. G. Micr, . «+ 15’. 56”,01 Wie Mick, . cis 2 ios oa 0 A set of ten, all agreeing on the sextant, on the limb, and arch of ex- CCES 5S a hes le UES gee I 5. §5”,4, Sept. 11, TE. Se Wi D.O. G. Micr. 3.5.3. 19. Error of V. + 2 ar gO § 15! 57" Ae ©. S. Dr.W. Micr. 15.41.4 15’. 57,1 Sextant, 15°. 55.43"... . 15’. 58”,0 15’. 56”,54 Sept.17, R. D’s. Dr. of ©. 15. 43. W. a 15’. 58",3 , " Sextant, 70°. Pee oh Tol aS 19! 58!,9, Ee Sept. 27, DiO. Gi Mier. tii Sor .48 PbO) 14585 Wire Micr. C0, 2’ 6 2) & at 16’. 1",95 16. Vee Sextant + 3%, «+6 +0+ +) 16’ 1”,70 - MICROMETER MEASURES. 97 Semidiameters of)as given Observations Oct, 4, 1794. S. Dr. ©> in the Nautical Almanack, of the sun’s D. O. G. Micr. J . s e ° . 16’. gu” ay 1 1 , " Belin seer eee CIE. 41 Cig 3”,6, . . > . BeniahL G) 3, 2 c.5 5 +> of XO" 3°50 diameter, SES The wire micrometer measures, taken from this time till the next vernal equinox, are omitted; inasmuch, as being taken nearly in a vertical circle, the excess of the effect of refraction on the sun’s L. L., required a correction from the tables of refraction; which is lable to some degree of une certainty at low altitudes, They were found, however, to agree very nearly. Dec. 14. By a set of measures of the sun’s diameters, on the limb and arch of excess, taken, with great care, parallel to the horizon, images extremely distinct, and no discernible spring whatever in the index. Dec, 15, @’s S. Dr, ++ 3" =) 16”.18”,0 Pore: Gee) 4 ey eet k 16’. 17,83 Semidiameters of ©, as given in the Nautical Almanack. Dec. 29, Dr OoGe Miory je 51S LEHSReD 1’, 19.2 Sextant -+ a ee ee © « @ 16’ 18”,0 ip ar ae DD Feb. 16, 1795. DPOLG. Miers 888 69.) 2°27 A6'~ YS" AS Set of good observations > ~ 16’. 13”,7. with sextant, .....) 16’. 13”,0 £8 Observations of the sun’s diameter, a re MICK. .e + et hte . ON COMPARATIVE 1795. March 30th and 3ist. “Day very favourable; various.isets of measures. taken with divided object-glass and wire mictometers. The -extremes of the divided ohject-glass micrometer measures never exceeding 1%. Those of the wire microme- ter 0. S.,.Dr.@: Do ra, Ric ua ae, ee En ee 16’. 1”,9 eee June 8th. The two different.micrometers were applied to the 42-inch achromatic telescope, and vg scales verified. Semidiameters of ©), as given jn the Nautical j)Almanack. Sameday, D. O. G. Micr. ees oe @, 15’. 46! 1,95" , an “Wire Micr.- . 22's; 15’, 46,45 15’, 48,1. June 9, D.0.G. Micrs 6.4). £ TQIG' A", 95 GF pry Troughton’s sextant + 3”, § 15’. 46,0 aah een June 15, D. O. G. Micr. 6 8 '@, @.. 6 4 15’. 45,9 i i r " Wire Mier, o 8 @ : ary het es’ } 15". 46,7 5. AT ode June 19. The measures, with the different micrometers, were taken-with-the greatest care ; and a mean of internal and external contacts, of the _suun’s limb to ‘the micrometer wires, ,was used as the wmeasure of the -sun’s disk by the ywire«micro- mefers/: «J - cee ee ata * This curtation of the-sun’s-semidiameter is the effect of the difference of refraction of the L. L. of the sun from the upper. _’ MICROMETER MEASURES. a Observations Mean apogealsemi- Semidiameters of ©» of the sun’s S. Dr. ©). diumeter of the sun. asgiven in Nau. Alm, diameter. D. O. G. Micr. 15.5 45" 26 f it & +f a “ Wire Mier. : 15’. eae Ae eee fis eaters V788. The sextant, on June 25th, shewed, from a careful set of measures, the apogeal semidiameter of the sun, 15". 44”. “ oe . : . clérmuination On attending to the difference of the sun’s apogeal semi~ of the sun's ‘diameters, as shewn by the divided object-glass micrometer, apogeal dia- and the wire micrometer, I had recourse to some former as- ™*'S* tronomical records on this subject. By referring ta De la Lande’s Astronomy, article 1387, I find, that, in the year 1758, Dé la Caille observed the apogeal semidiameter to be 15’. 47.2; and that De la Lande, in 1760, made it 15’, 4525. These two measures happen to correspond so exactly with mine, as made with the different micrometers, that it may be a matter of some consequence, to inquire, what kind of micrometers they used to deduce their respective semi- diameters. | It is unnecessary to extend these observations any farther. I shall, therefore, only add to this paper, that it will appear, by . comparing the divided object-glass micrometer’s measures of the sun’s diameters, of Decembers 15, 1794, and of June 19, 1795, that the difference of the perigeal and apogeal diameters of the sun was found to be 65",14. De la Lande found this difference 64,8. but he calls it, in round numbers, 65". _ Note. Where no notice is taken of the time of observa- tions, it is to be understood they were taken very near to noon, afid as soon after each other, as micrometers could be changed. ’ The originals of these observations, and several others, are. * This measure comes nearer to the calculated apogeal semi- diameter of the sun than the former; but as, at the making. of thesé observations, the state of the dir caused the sun’s limb te undulate, perhaps the divided object-glass micrometer, having @ much greater magnifying power, than was used withthe wire micrometer, its observaffons may have been rendered more un- certain, Excellence of the Reflecting Telescope. Particularly the . Newtonian. REFLECING TELESCOFE. to be seen in the registry of observations kept at the Observa+ tory, Armagh, for the years 1794 and 1795. I have the honour to be, Dear Sir, Your faithful and obedient Servant, JAMES A. HAMILTON: Observations on the Metallic Composition for the Specula of refiects ing Telescopes, and the manner of casting them: also, a Me- thod of communicating to them any particular Conoidal Figure: with an Attempt to explain on scientific Principles, the grounds of each Process: and occasional Remarks on the Construction - of Telescopes. Bythe Rev. James Lirris* "Tuere are but few things produced by the united effort of mechanical artifice and intellectual labour, which have done more honour to the ingenuity and invention of man, than the reflecting telescope; which has many advantages over any of the dioptrical kind, notwithstanding their improvement, by acromatie glasses. It will bear a greater aperture, and may be made to magnify more, (as being more distinct,) in propor- tion to its length, than the others, as they are at present made; and its dimensions and powers are unlimited. What its excel- lence is, especially the Newtonian construction of it, has been proved by Dr. Herschell, to his own honour, and that of the age, and country, and patronage, which encouraged his la- bours. Accordingly, the persons, eminent for science and — mechanical ingenuity, appear to have felt a peculiar and disin- terested pleasure, in contributing to its improvement: and the late discovery of a metallic composition for the mirrors of it, which will bear as high a polish as glass, reflect as much light as glass transmits, and endure almost equally well, without con- ‘tracting tarnish, is a farther encouragement to prosecute its improvement to perfection. * Trish Transactions, Vol. X. REFLECTING TELESCOPE. St Among others, I had formerly, from admiration at its con Introduction trivance, bestowed some attention on the mechanism of this —— its _ instrument: and, as it would have spared me some expence of time and trials, if any other person had previously suggested to me the hints, which 1 am to relate; I imagine they will be of use to others, in directing or assiting the course of their la- bour, in the same pursuit. I had also taken some pains, to understand the merits of the different constructions of this te- lescope: but, as this inquiry ended in a conviction, that the Newtonian form of it is the most perfect that can be hoped for; (it being the nature of its great author to persevere in his researches, till he had arrived at a complete solution of his doubts, and comprehension of the subject ;) so I have only to report what resulted from my experience in the mechanical fa- brication of it, as to the method of casting the mirrors, and communicating to them the proper figure. Before I had heard of the improvements of the Rev. Mr. On the nature Edwards, in the composition of the specula for telescopes, I of the Meta — had made many experiments myself with that view; which lead me to give full credit to his report of the superior excel- lence of that composition which he recommends: because I had found, that the qualities of hardness, whiteness, and indis- position to contract tarnish, necessary to ,a speculum, could not, by any admixture that I could hit upon, be produced, un- less the metal were so highly saturated with tin, as to be ex- cessively brittle ; and because I found that this brittleness, however inconvenient insome respects, was necessary to ren- der it susceptible of the highest polish: for no metal yet known, except steel, (which, from its disposition to rust, is un- fit for this. purpose,) will take as high a polish as glass will, un- less it be more brittle than glass. And indeed this property is common to all substances which we know, that are capable of such polish: they must be very hard, and, as such, brittle; for the polishing powder employed would stick and bed itself in any soft metal, instead of cutting and polishing it. From the result of my trials, I-contented myself with the Silver renders composition mentioned hereafter, as being in every respect suf- *¢ Soft; but the ficient for the purpose, and inferior to none in whiteness, lustre, pat ae tended and exemption from tarnish: for, as to the addition of silver, I ound that, when used even in a very small quantity, it had aa extraordinary property of rendering the metal so soft, that I was 32 PEFLECTING TELESCOPE. deterred from employing it: and unless it shall be found that, without this effect, it makes the metal less porous than other- wise it might be, or less frail and brittle, I am certain that it may, in every other respect, be dispensed with. I had no op- portunity to try it, inthe precise quantity Mr. Edwards recom- mends, (though I did so before, in very nearly that proportion, ) since I first saw his memoir on that subject. Sir Isaac New- ton made trial of a very small portion of it, and found the same effects from it as I experienced: but it is possible, that, if it were added in the just proportion discovered by Mr. Edwards, it would be an improvement, and useful ingredient,.in the com- position *, T must observe here, that a metal, not liable to contract tare aes gi san nish from the air, is otherwise susceptible of it accidentally ; from imperfect when there happen to be minute holes in its surface, caused by sean the air, or sand, &c. in casting it. Such cavities will be filled with the dust, or rusty solution of the brass, in grinding ; which will, in time, become a sort of vitriol, and act on the contiguous parts of the speculum, producing a canker in it, which will spread, in form of a cloud of tarnish, around each cavity. Insuch a case, to prevent this, I would advise, to lay the mirtor, as soon as polished, in warm water, and, after drying, while it remains heated, to rubit over with spirit-var- nish , from which it may be cleansed, hy a piece of fine linen dipped in spirit of wine. The varnish will remain in the cavi, ties; and, by defending the impurities in them from the action of the air, will probably preserve them from becoming corrosive to the metal. rT .. From numerous experiments, of the qualities of different com’ The Composi- Phys i : tion, copper, positions, made by several persons, it appears, that no combi- oo ony sil- nations, ofany other metals or semi-metals, are fit for specula, Tr, and ar- ; s€nic. '* Having read somewhere, that zinc and gold made the best speculum-metal, I tried it ; and found, that the zinc was sublimed from the gold in fusion, and arose to she top in the crucible, forming a white, hard, spongy mass. The metal, called tutanag, is fit for specula, when melted with tin; but Jam certain, that what { procued, under the name of tutanag, was a mixture of brass and copper, &c.; for the zinc, in the brass, rose from it, during the fusion, in white flowers, REFLECTING TELESCOPE. 33 except those of copper, brass, tin, silver, and arsenic. I tried no semi-metal, except the latter, which whitens copper, and unites intimately with it: because it is stated, in the treatise of the Art of Assaying, by the observant and accurate Cramer, that all the semi-metals rise in flowers, during the fusion: which would certainly make the metal porus. On this. ac- count, 1 would have rejected the brass, because of the zinc contained in it; but that it seemed to render the composition whiter, and less apt to tarnish, than it would be without it. It will have little tendency to rise in flowers, if the speculum-me- tal be fused, with the lowest heat requisite, and if the brass be of the best kind; because, in this, the zine is more perfectly united with the copper, and both are purer. I used, for this purpose, the brass of pin-wire : and, because the quantity of 74. bras e it was only the one eighth part of the copper employed, which, I imagined, would receive too fierce a heat, if put alone into the melted copper ; I first added to the brass, in fusion, about an equal quantity of the tin; and put the mass cold into the melted copper ; supplying afterwards the remainder of the tin, and then the arsenic ; the whole being generally in the follow- ing proportion: viz. 32 parts best bar copper, previously : fluxed with the black flux, of two parts tartar, and one of nitre, oe 4 parts brass, 16$ parts tin, and 12 arsenic. I suppose, with others, that, if the metal be granulated, by pouring it, when first melted, into water, and then fused a second time, it will be less porous than at first. In this process, whatever metals are used, and in what pro- How to deter- portions soever, the chief object is, to hit on the exact point of MIDE the Sa- i i 2 ~ turation of the saturation of the copper, &c. by the tin. For, ifthe latter be tin and copper. added in too great quantity, the metal will be dull-coloured and soft; if too-little, it will not attain thé most perfect white- ness, and will certainly tarnish. It is too late to discover the im- perfections of the metal, after the mirrors are cast and polished ; and no tokens given of them (that I know) are sufficiently free from ambiguity, But I observed the following, which: proved, in my trials, at first view, indubitable marks of the degree of | saturation; and I think it fit to describe them particularly, as they have not, to my knowledge, beén noticed by others. When the metal was melted, and before I poured it into the Mask, I always took about the quantity of an ounce of it, witha Vor. XVI.— Jan. 1807. No, 65. D 84 REFLECTING TELESCOPE. small ladle, out of the crucible, and poured it on a cold flag; and observed the following appearances : From a cast First. Ifthe metal assumed, in cooling, a lively blue, or Specimen. purple colour, commonly intermixed with cloads, or shades of green or yellow; and if, when broken, the face of the fracture exhibited a silvery whiteness, as bright and glistening as quick- silver, without any appearance of gfain, or inequality of tex- ture; then the degree of saturation of the metal, “_ the tin, was complete and perfect. And the frac- Secondly. If the surface of the metal became of a dun ot ture and Co- mouse colour, and especially if of a: brown or red; and, when ela broken, the fracture exhibited a more yellow, or tawny hue,’ than that of quicksilver; then the quantity of tin in the com- position was deficient, and it was necessary to add more.* — Thirdly. If the colour was an uniform dull blue, like lead, ‘where broken, discovered a dull colour, with a coarse grain, like facetts; the due saturation was exceeded, and there was an over proportion of tin in the metal. Explanation of These colours would be more distinct, if a small quantity the colours. —_ of the metal were cast in a flask, which had been previously smoaked, by a candle, made of resin mixed with tallow; in which way I used to prepare the moulds. I attribute the formation of the colours to this: that, as the calx of every metal has its own peculiar colour, so, the heat of the melted mass, calcining some of the particles on its surface, which are in contact with the air, these display the colour of the calces of those ingredients which prevail in the composition. Whence, it may be expected, that, if the copper is the redundant metal, the mass will exhibit a reddish tinge, which is appropriate to the calx of copper; and, if the tin be prevalent, a blueish die ought to appear. Either of these colours, therefore, appear- -ing unmixed, shews the redundance of that metal, to which each belongs. And, as brass, when cast alone, has always a * This can always be done by degrees, and without any trou- ble, till the point of saturation is found ; whereas, if too much tin were added at first, there would be a necessity for melting more copper separately, and repeating the whole process: and different specimens of copper will require different proportions of tin; so that the due quantity can never be known, a priori, but on trial only. ‘REFLECTING TELESGOPEs yellow tinge, so, when these three colours are exhibited in a cloud-like mixture, they shew an equality and due proportion of their respective metals m the compositiun. When too large a mass of the metal is cast together, ils intense and lasting heat calcines the surface so deeply, as (when exposed to the air) to obscure the colours; so that a small quantity will best serve to exhibit them. As to the method of casting the mirrors, it has been di- Method of rected, to leave the ingate, or superfluous part of the cast, “* so large, as to contain a quantity of metal, equal to that in the mirror itself; which would occasion a great waste of it, and render it not easy to cast, at once, more than one mir- 38 _ For in each mould; and »even this might be done so injudi- Large ingate ? ciously, as not to afford security against a miscarriage of the cast. But it will appear, that this great quantity of metal and incommodious manner of casting it, are by no means ne- cessary. However, a judgment cannot be formed, of what may be the safest and most eligible method for casting the mirrors, unless it be considered, what are the circumstances attending this operation, in the case of malleable metals ; and how the management of speculum-metal, in this respect, must differ from that of them: since there must be peculiar difficulty in casting, in sand; a metal more brittle than glass. When any fused metal is poured into the flask, the external Effects of the parts of it, which are in contact with the mould, congeal and harden sooner than the internal parts; and form a solid shell, filled-with the rest of the metal, in a fluid state. This will, consequently, remain in a state of greater expansion, from its heat, than the external crust; and its particles will, in the act of shrinking as it cools, recede from one another, as being more easily separable, and cohere, on each side, with the par- ticles already fixed and grown solid: by which means a va- cuum will be formed in the middle, and this will be gradually filled by the superincumbent metal, which has been later poured in, and remains longer in a fluid state. But, when there is no more metal supplied. the void, which was in this way latest formed, remains unfilled ; and then the shell of the metal, adjacent to the vacuum, as yet remaining soft, and unable to bear the weight of the atmosphere, resting on it, sinks, and is pressed down into the vacuum: hy which means, D2 contraction of fused metals, 36 -—particularly in speculum- metal, REFLECTING TELESCOPES a pit or cavity will be constantly and necessarily formed in the face of the cast, in that part of it which was last congealed; which cavity will commonly be larger or smaller, in proportion to the quantity of metal in the cast. , The event will, in this respect, be the same with speculum- metal, as it is, in the case of that which is tough and malle- able: only that, as the former, in cooling, arrives sooner at its natural state of hardness and brittleness, its external solid shell will not bend, but break, and fall into the void part under it; and thus form cracks, or abrupt chasms, in the places, where tougher metals would contract only regular depressions. And also, when the body of the east is small, or the mould is so damp or cold, as te congeal, not only the surface, but the substance, of the cast too soon, and thus prevent a gradual ‘influx of the fluid metal, to keep the central part as distended, as the exterior shell was, when it became fixed; the farther contraction of the interior parts of this. brittle, refractory metal, after it has become solid; will be apt to form rents in it, be- Remedy: by a supply of the melted metal, _ cause its substance will not bear extension, without rupture. It would be an obvious remedy of the above inconvenience, if there could’be contrived a reservoir of fluid metal, to des- cend into the interior part of the cast, and fill up the void made in it, as fast, and as long, as it is forming bythe cone traction of the metal. Now, this is effected, by having’a jet or appendage to the cast, of sucha size, form, and position, as will be effectual to retain the metal, composing it, in a state of fluidity ; and also to suffer it to descend into the inte- rior of the cast, until all parts of the same become fixed, and incapable of receiving any farther influx of metal. For.thus,_ ‘all the imperfections, that would otherwise be in the cast itself, will now exist only in the appendage to it, which is -@ supernumerary part, to be afterwards seperated from it. ‘This appendage ought to be of the form of a prism, and’ as ‘nearly that of a cube, as the operation of moulding it in the rin the form of a prismatic appendage, sand will permit s for, in this gross shape, the metal in it will be the longer cooling. It should be connecied with that part, of the mirror, which is uppermost in the flask, and joined ‘to it by a neck, equal im thickness to the edge of the mirror, (but so posited, that the face of the mirror may project-a little above it), and, in breadth, about twice the thickness. This neck ought to be as short as possible, i. e. Just so as te “REFLECTING TELEZCOPE, permit it to be nicked round with the edge of a file, in order to break off the prism from the mirror when cast: for thus the ‘heat of the large contiguous body of the prism will keep the neck from congealing ; which, if it happened, would stop the liquefied metal, in the prism, from running down into the mirror. And, to prevent this, the prism ought not to form directly a part of the main jet or ingate, by which the metal is poured into the flask; for so the jet would cool sooner than the large mass of the mirror, and bear off the weight of the atmosphere, which ought to press on the fluid metal in the prism underneath, and force it down into the mirror, to fill up all vacuities in it. Both the prism and the mirror, therefore, ought io be. filled by a lateral channel, opening (from the principal ingate) into the top of the prism; which latter should ‘be formed broad and flat, and not taper upward, like a pyra- mid, lest, by cooling where it grows narrow, it might forma solid arch, and oppose the pressure of the atmosphere. When it is fashioned, as here directed, and made of a bulk equal to a third or fourth part of the mass of the mirror, or even a fifth or sixth part, when the mirrors are of large size, there ‘will ever be found, in the top of the prism, after the metal is cast, a deep pit or cavity, which contained the metal, that had ran down into the mirror, after the outer shell of the mirror, and sides of the prism, had become solid and con- gealed; and the mirror itself will be found perfect, without any sinking or cavity; which could only be formed by an injudicious disposition of the jet or appendage, permitting the metal in it to freeze sooner than the whole mass in the mirror, and thus stopping its descent into it.. If several mirrors be cast together, in the same flask, there_must be such a separate appendage made to each of them. ? $7 In this manner I have (without a failure in any) cast many The small spe« mirrors of different sizes, and sometimes several of them toge- mirrors for Gregorian telescopes, cannot be cast in this man- ner; for their masses being but small, they cool too quickly, to receive any additional infusion of metal; and their outer edges, suddenly forming a solid incompressible arch, the central parts, in contracting towards it on every side, sepa- rate, and are rent asunder. And this has happened, even when I cast them in: brass moulds made. red hot : on which D3 culums to be i ‘ made out of a ther in one flask. But very small ones, such as the little par, 38 Reference to Edward’s Trea- tise. See our Journal, quarto series, vol. V. 'Figuration of the mirrors. REFLECTING TELESCOPE. account, | have been obliged to form them out of pieces of the: - metal, cast in long thin ingots or bars; which, by nicking them across with a file, could be easily broken into square pieces, whose corners could be taken off, and rounded in the same manner. I do not repeat the other precautions to be observed in this process, which have been already so well and sagaciously described by the Rev. Mr. Edwards: but the circumstances above mentioned, a prudent attention to which, is, in my’ opinion, essentially necessary to the success of it, are not to be collected from any directions published on the subject that are’ known to me. And though particular artists may, by large experience, arrive at a sufficient knowledge in this’ matter, for their own practice; yet, to render that knowledge general, and to contribute, as far as I could, to the improve- ment of this instrument in any hands, being the design of this essay, I thought it necessary to state the above particulars fully} though I doubt not that these, as well as other matters of moment in the operation, are known to many, who chuse not to make them public. Thus the great skill, in the con- struction of the telescope, acquired by Mr. Short, seems not to have been transmitted to any successor. I come now to speak of the most difficult part oF the me- chanism of this instrument, that of communicating a proper figure to the mirrors; on which depends the powers of the telescope, when its dimensions are given: for the manner of polishing them, to the highest degree of lustre, has been al- ready well understood did described. They who have tried this part of the work, and know how inconceivably small is that incorrectness of form, which will produce grievous aber- rations of the rays of light, will, I am sure, readily subscribe to the assertion, that * hoc opus, hic labor est.’ Methods have indeed been proposed for accomplishing it; but not a single hint given, that I know, of the modus operandi, or the grounds of these methods: insomuch, that, when I first tried to polish mirrors, I had no idea why any figure of them, different from that of a sphere, should result from the modes of polishing recommended. But, on my making the altempt, in the ways proposed by Mr. Mudge and by Mr. Edwards, I was surprised to find, that sometimes a spheroidal or other irregular figure, and sometimes (though rarely) a conoidal one, was produced REFLECTING TELESCOPE. 9 fo) by each: the cause of either being to me then unknown ; and disappointment or success appearing to depend on mere accident, and not on the degree of pains and accuracy used in the process. ° At length I began to suspect, that these variations, in the The methods event of the process, (which will be hereafter accounted for,) eles arose from some property, not adverted to, in the pitch that from the pro- covered the polishing tool ; which material has been generally PoVy Ss Pe: used for this purpose, of communicating a proper figure, as well as a high polish, to the mirror, since it was first recom- mended by Sir Isaac Newton; being commonly spread on the polisher, to about the thickness of a crown-piece, and then covered with the polishing powder: (the manner of doing which I suppose the reader to be acquainted with, as also with what has been made public on the subject, by Messrs. Hadley, Mudge, Edwards, &c.;) and I was confirmed in my suspicion, from the following reasons, after I had found them approved by many repeated and diversified experiments. Pitch is a soft unelastic substance, which; as such, will The pitch, ; Hele te -_ though hard, is suffer a permanent change of form, when it is made to sustain yielding. - a degree of pressure sufficient to communicate an intestine motion to its particles: and this property directs us to con- sider, what may be the effect of the pressure of the mirror on it, when spread on the polisher, as to the figure it may then gradually acquire, during the operation of polishing, and the resistance and friction it will. oppose to the mirror; for, by reason of the tenacity of its substance, it -will resist a certain degree of pressure, without change of its form, but will yield to a greater pressure. But it is by its resistance the mirror ‘is worn down end polished ; if, therefore, that resistance be ° not uniform and equal, on the whole surface of the polisher, neither will the abrasion of the mirror be equal in every part; the consequence of which must be, that both will degenerate from an uniform curvature, i..e. from a spherical figure; the mirror from unequal friction, and the polisher from its mobility, by which it will adapt to the successive alterations produced... in the figure of the mirror; their mutual action and reaction inducing a change in both.* ; . ee This change, however, being so little, as to be imperceptible by the senses, and, in the imagination, referable to various other . D4 40 The law of its giving way. Explanation. Yt recedes uni- formly, ' REFLECTING TELESCOPE, As the pitch is (in ourpresent inquiry) to be considered as an homogeneous substance, we must suppose, that its resist~ ing force, as well as that of the pressure of the mirror on it, are uniformly diffused over the surface of the polisher: and, from hence, it may not, perhaps, be easy to conceive, how the surface of the mirror could sustain from it any inequality of resistance and friction, In fact, these would be equal and uniform, in every part, if the pitch were a substance, either of perfect hardness, or perfect fluidity: but it will. hereafter appear, that its consistence must not be so hard, as to render it incapable of any change of form: but,:on the contrary, sa soft, as to yield, in a small degree, ‘1o the pressure of the mirror,: at the same time, oppgsing a resistance, sufficient to wear down and polish it: and-the inquiry is, how that resist- ance is modified. Bodies of perfect hardness, such as glass, flints, &c. will not admit a total intimate change of their form, in all their dimen- sions, without a dissolution and permanent separation of all the particles composing their masses, (except when they are brought: to a state of fusion by heat). But soft, viscid, semi- fluid bodies, such as lead, pitch, &c, will suffer such change, _ preserving the cohesion of their particles, yet, at the same time, undergoing a general intestine motion: of all the par- _ causes, it becomes necessary, in order to establish the true cause, not only to deduce its existence and effects solely from reasoning on physical principles, but also to obviate other different conjec- tures that might be formed, by stating fully those circumstances that take place in this operation ; and which, indeed, are neces- sary to be clearly understood in judicious practice, Both these ends cannot be answered, in a disquisition new and intricate, without a minute explanation: and this, I hope, will be received. as my apology, for the prolixity of this account, which I would. » gladly have curtailed, if knew how to do s0, without making it less intelligible or useful to the practical optician. This class of readers will forgive any diffusiveness on a mechanical subject, if the perusal may tend to spare them the greater labour of fruitless experiments 5 ; or afford any hint towards conducting them more judiciously ; and as for their use this paper was designed, I have adverted to such various matters as I thought most worthy their attention; and which yet have not been so fully and familiarly explained by others, as. they ought to be, for the instruction of an artist, REFLECTING TELESCOPE. Al ticles among themselves: so that the coat of pitch, pressed, on each side, between the parallel surfaces of the mirror and polisher, will, by their force, be equally extended laterally in every direction; by which an equal quantity of motion will be communicated to all its particle: since no particles, except those at the extremities, can move, without protruding others, and these, the rest, successively, as if the mass were a fluid body. But, though all parts of the surface of the polisher receive an —but with dif- equal pressure and motion, all do not exert an equal degree of cugen resistance to that pressure: for those parts, that cannot move ent parts of the without displacing and overcoming the resisting tenacity of a sapien. greater quantity of the surrounding mass of pitch, than other parts do, must oppose the greater resistance to the mirror, as having that of the other parts superadded to their own. For ascertaining this, the force impressed, and the quantity of pitch, confining any annular tract of the polisher, should be computed. In the present case, where the coat of pitch is a thin equal statum, of circular form, we need regard only its su- _perficial dimension, an‘ consider all parts of it as alike situated in the above respect, which are equidistant from the center, or from the outer edge of the polisher. To this purpose, let the surface of the polisher be conceived Deduction of to be composed of an indefinite number of concentrical zones or wa ae annuli, Each. of these will sustain an unifurm pressure, from pressure. the mirror, proportional to its area, because, the force im- pressed on the mirror, and its attraction to the polisher, is equally diffused'on it. The areas of these annuli, taken sepa- rately, are the differences of the two circles, whose periphe- ries inscribe and circumscribe each of them; and they are consequently to each other, as the differences of the squares of their diameters, or as those of their radit; and the series of them taken, in order, from the center to the extremity, are strictly as a rank of igurate numbers proceeding from unity, viz. the odd‘number 1, 3, 5,7, &c. But, since their breadth is supposed to be infinitely small, they may be taken as. propor- tional to their mean diameters or radii, i. e. as their distances from the center of the polisher ; which distances will, therefore, represent the pressure on each annulus, and the quantity of ‘ motion communicated by that pressure ; sceing it must be, as AS This resistance may be raised, —by taking away some of the surface of - the pitch at proper places. REFLECTING TELESCOPE, the number of particles the annulus contains that are moved ; 1. €. as its area. But the resistance to the force impressed, on any annulus, being as the quantity of pitch to be put in motion by it, will be different, not only as the annulus is nearer to, or farther from, the margin of the polisher, but different, also, as this has either one margin only, or two, i. e. when the polisher is entirely co- vered with pitch, or when it has a space left uncoated at the middle; Which latter always is, and must be the case, when the great mirror of the Gregorian telescope is to be polished, wiltich has a perforation at its center. First. When there is no vacant space in the middle :- the resistance to the several annuli will be as the circumambient spaces only; because, the pitch not being compressible, it is only into these, and not towards the center, it can, in yielding tothe force or weight of the mirror, extend itself, by lateral motion: and the space, surrounding any annulus, is the diffe- rence between the circular area of the polisher, and that in- scribed in the annulus: and is, relatively to the rest, measured by the difference of the squares of their radii, viz. of the dist-- ances of the edgé of the polisher, and that of the annulus, from the center. But since, in this case, the bodies (of pitch) are unelastic, there can be no augmentation of motion; nor can Effect of acen- tral hole, the quantity of motion and action communicated, and, conse- quently, the resistance to it, and reaction, exceed that which is impressed: on which account, I imagine, that the resistance to the several annuli is to be taken as proportional to the pres- sures they sustain, and measured by them, i. e. by their magni- tudes or areas, or the number of particles in them, to which a motion is imparted ; which were stated to be as their respec- tive radii or distances from the center: and, consequently, ] suppose the resistance to be the inverse of this, or as the distances of the annuli from the outer edge of the polisher ; which distances measure the direct resistance, or the quantity of pitch, to which equal motion, with that in the respective annuli, is communicated. And from hence it follows, that, if a mirror, previously ground toa spherical figure, were to be polished on such a polisher as this: the resistance and friction of the pitch, being greatest, and increasing to a maximum at the center, and diminishing towards the extremity, would wear down and - REFLECTING TELESCOPE. 43 polish the mirror, most in the central part, and least towards ‘fits edges; thus giving to it a curvature, the reverse of a conoid, which it ought to have, and which it can never at first acquire correctly, by any other mode of polishing, but that of wearing it most down (and thus reducing its curvature), towards its extremities.* Secondly. When there is a hole made through the center of the polisher, or a void space left there, uncoated with . pitch.t . . In these circumstances, the pitch will have liberty to ex- —shewn in - pand itself (when yielding to the pressure of the mirror), 2 ye Lae towards the center, as well as the edges of the polisher: and, a polisher. as the resistance and friction, in any annular tract of it, is as the direct extent of pitch, bounding it on either side, it fol- lows, from what has been laid down, that it will encrease in any part, as the-distance of the same annulus encreases, from each extremity of the coating of the polisher ; and will be in a ratio compounded of the distances, from the interior and exterior margins of the pitch. So that, if the breadth of the polisher between these margins were, (for example,) 5 inches: then the pressure and friction in the middle tract, equidistant from the outer and inner edges, ‘would be, to that prevailing at the distance of half an inch from either margin, as 63 to 235 (nearly as three to 1;) and the same, at proportionate dis- tances, in polishers of any other size; which unequal pres- sure could never produce, in the mirror, a regular curvature of any species; and, in the spaces nearer to the margins, the inequality of pressure would be still greater. Whence may be conceived the impossibility of pean mirrors correctly, on - polishers disposed in this manner, without some remedial con- trivance; whether the face, or area of them, be of a circular shape, as directed by Mr. Mudge and others, or oval, as pro- posed by Mr. Edwards: for the mirror would be thus least reduced, and left of a spherical form, at the middle and edges; and be worn down, and hollowed into a different and irregular curvature, in the intermediate tract. * lt will be hereafter shewn, for what particular purpose, solely, such a poljsher may be employed. + There ought always to be a hole made through the polisher ‘: 'o prevent t the confinement of air or water, near the centre of it. 44. Remedies. Make the po- lisher larger than the mir- ror. Contract the center hole. Cut out some of the face of the polisher where the re= action is great- est. In this way, the small, as well as the large specu- lums, may be duly figured. KEFLECTING TELESCOPE. ‘For these inconyéniences, however, arising from the un- equal friction of the polisher, there are the following easy and adequate remedies : which will, in the sequel, be more fnlly explained, and applied as in practice, to effect the degree. of curvature, or any correction of the same, which may be requisite. . ) First. Sitice the curvature of the mirror ought to be gra- dually-reduced towards its edges, which can only be effected by an increase of friction in the corresponding part of the polisher; and that this latter effect is to be produced in any part of it, by enlarging the surrounding coat of pitch: it fol- lows, that, for this purpose, the breadth of the polisher must be enlarged above that of the mirror; and .this in the same degree, as the curvature of the mirror isto be diminished: so that the polisher is to be of greatest breadth, for a mirror. of an hyperbolic, and least, for one of a spherical figure. This, however, is to be done, under the limitations hereafter mentioned. Secondly. To preserve the regular gradation of curvature. towards the middle of the mirror, the uncvated space, at the center of the polisher, should be contracted to a certain limit, which will be defined; though, for the reasons above men- tioned, it can never be filled up altogether. Thirdly. Where the resistance and friction of the pitch, 3 in any tract on the face of the polisher, is computed as above, or found in effect, to be too great ; it may be lessened and regulated, in any degree, by cutting, out of that part of its. surface, some of the pitch, at proper imtervals, in narrow. channels or furrows: the number and depth of which ought, to be proportioned to their distance from the edges of the coat oi pitch directly, and to the reduction of curvature, proper te the corresponding parts of the. mirror inversely, and should be in a ratio compounded of both ; for, by these cavities, the con- tinuity of the pitch being dissolved, its resistance, Phesitiyion thereon, may be modified at pleasure. In this manner may the polisher be so digpostel, as to come municate a correct figure to large mirrors, and even to those of smallest size. Now, whatever success may have attended the. efforts of other, persons, in communicating a proper figure to the great speculum, (especially Mr. Short, whom I have, manifold reasons for believing to have been among the most’ ~~ 9 REFLECTING TELESCOPE. BS eminent opticians, as well as artists, that have laboured in the improvement of this instrument;) I have not heard, that any method has been. proposed, of communicating, to the Jittle mirror of the Gregorian telescope, any other than a spherical form, which yet may in this manner be done. And it must, in this telescope, be a thing most desirable to accomplish ; especially when its size and aperture is so great, that it ‘would be difficult to impress, on the extensive surface of its great mirror, (merely by the small alteration of figure, which could be produced, in the delicate operation of polishing,) the degree of change, from its prior state of spherical curva- ture, which would he requisite; since the defect of form, in this mirror, may, in. these cases, (as will be shewn,) be easily compensated, in the figuration of the little mirror. For the greater size of this latter, in such instances, will render it ‘capable of more steady handling and motion, and more equal pressure; and so more manageable, and susceptible of a cor- ‘Tect figure, in proportion as'the encreased magnitude of the “great mirror renders it unmanageable: which «is, plainly, a great advantage, in the fabrication of this telescope; whose Mirrors will thus, in the cases where it is most especially ne- cessary and desirable, admit mutual correction and compensa- tion for each other’s defects. The principles, or physical causes, operative in this process, Difficulties of _as above stated, seem to be incontrovertibly evident; and, as ‘¢ ean Lam nof aware of any. paralogism admitted. in the reasoning ‘upon them, I must suppose, that a mode of operation, con- formable to these principles, is the thing chiefly requisite to ‘ensure success. In this view, I have attempted to conduct _the process; and, as the almost insuperable difficulties attend- ‘ing it are felt, even by those whose inventive powers and _Tesources ought to afford the highest hopes of accomplishing _the object, and yet disappoint them in their attempts at high perfection;* so I, among others,,may be allowed to state the * Sir Isaac Newton, who had himself laboured in this under- ’ taking, of polishing the concave mirror of his own telescope, and _ with suchtalents for the work, and such success, as to discover _ that method of doing it, which has, to this day, been followed, observes, (to use his own words) that ‘ optict instruments bd might be brought to any degree of perfection imaginable, pro- * vided a reflecting substance could be found, which would po- 46 Argumentsand inferences res- pecting the process of po- REFLECTING TELESCOPEs difficulties; that, to my apprehension, occurred in the enter¢ prize, and to obviate objections; as, from hence, there may be suggested some hints, to facilitate or abridge future labour to others, or to prevent hopeless trials: I must observe, then, that different effects must necessa= rily follow, from using, in the process of polishing, pitch of a softer or harder consistence. If the pitch be ofa temper quite lishing murors. hard and unyielding, no part of the surface of the mirror can be made to suffer a higher degree of friction than the other parts of it, unless these latter parts be elevated and detached ae the face of the polisher, and disengaged from contact with ; because, in this case, both mirror and polisher are sup- a to preserve their general shape regular and unaltered ; and therefore, the contact, and, consequently, the friction, must be either complete and equal, on the whole surface, or none at all. For, if we suppose, that, by the wearing down *¢ lish as finely as glass, and reflect as much light as glass trans- *« mits, and the art of. communicating to it a parabolic figure be ‘* also attained. But there seemed (said he) very great difficulties, “and Z had almost thought them insuperable, when I farther ** considered, that every irregularity, in a reflecting superficies, «‘ makes the rays stray five or six times more out of their true ‘© course, than the like irregularities in a refracting one; so that ‘© a much greater curiosity would be here —— than in Bgur- ‘* ing glasses for refraction. . .. . &c. <« But having afterwards thought on a tender way of polishing, ‘© proper for metal, whereby, as [ imagined, the figure would also “* be corrected to the last, (i.e. to the utmost) [ began to try what * might be effected in this kind; and, by degrees, perfected an «‘ instrument... .. &c. ... . and afterwards an otherone.” _ The tender way of polishing, which Sir Isaac Newton here mentions, was (as he afterwards described in his Optics,) to cover the polisher with pitch : and he declares, that he imagined the figure, as well as the pollsh, would. by means of this, be per- fected. Icannot help thinking, that this extraordinary man, - who was born to anticipate others in invention, as well as disco- very, had the same ideas as are here detailed, though he did not explain, nor, perhaps, succeed in, the application of them in “practice: for he states, (in his Principia) that a spherical mirror will reflect the oblique pencils, issuing from the extremities of the field of view, as truly as a parabolic one, and seems to despair of effecting a more correct figure, : ce REFLECTING TELESCOPE. AT of the mirror towards the extremities, it is made gradually to Arguments and change its spherical form, the part of its area, so abraded and mice diminished, cannot subside into a state of actual contact with process of po-~ the polisher, unless the other parts of it are elevated and disen- lishing Mirrors. gaged from the polisher, at the same time ; or unless it may be imagined, that the particles, worn off the mirror by friction, are applied and adhere to the corresponding parts ‘of the polisher, so as to raise and augment its surface, just as much as that of the mirror becomes depressed and reduced. If this effect could be supposed to take place, it would follow, that, in every variety in the direction of motion in the mirror, the friction must tend to wear down the edges, rather than the middle of the mirror ; because the motive force is always ap- ‘plied to a part of the handle to which the metal is fastened, raised more or less above the surfaces in contact. The effect of which must be, to communicate to the toremost or advanc- -ing half of the mirror’s surface, a pressure downward, on the face of the polisher, equal to the force expended in moving the mirror forward ; and thus to abrade and reduce the several parts of the mirror’s surface, proportionally to their respective distances from the center; by which its curvature will be made to approach to that of a parabola; by its wearing down most towards the edges: and this, weather the motion be con- . ducted in lines diametrically across the polisher, or with round strokes; so as that its center should describe, every time, a little circle, about the center ofthe polisher. This is, however, - entirely on the supposition, that the edges of the polisher become raised, by the adhesion of the dust worn from those ofthe mirror: for, ifthis were not the case, but that the po- lisher were to retain its spherical form, while that of the mirror was altered, the contact could not be general between .two surfaces of dissimilar shape. If these adhered together in one part, they must be dissevered in another: and the force, _necessary to seperate them in this latter part, which can never _be greater than that required to. move the mirror forward, must yet be more than equal to the force of cohesion, in the part of the mirror, which, in each stroke, is to be disengaged fiom the polisher. This pressure is found, in the case of rs bodies in contact, to be incomparably greater than the weight ' of the atmosphere, which is equal to about seventeen or eigh- _ teen pounds on every square inch of the surface of the mirror: 48 Arguments and inferences res- pecting the wracess of po- lishing mirrors. REFLECTING. TELESCOPE. | and, when this latter is brought so near that of the polisher, as to suffer friction from the powder bedded in it, their mutual attraction will amount to a much greater force than is requisite to move forward the mirror: no part of which can, therefore, be disengaged from the polisher, nor, consequently, be une- qually worn down, so as to produce, in its surface, a form dif- - ferent from a spherical one, or from that of the polisher. This reasoning and conclusion will equally stand, whether it be supposed, thatthe force of cohesion is confined to the very surfaces in contact, or extends to a little distance from them, diminishing in the duplicate, or any other ratio of that distance; and that the bodies are not wholly removed out of the sphere of attractiou when there is a small interval between them. For, as this force is greatest at the very surface; so, the bodies in contact cannot be disjoined atalf, to the smallest distance, but by a force superior to the whole cohesive force. It may, perhaps, be imagined, that the pressure of the atmosphere ought to be taken into consideration, and be added to the force of cohesion, which keeps the surfaces in contact with each other. But this pressare acts as much upon the coat or plate of water, which must be interposed between the surfaces of the mirror and polisher, as upon these surfaces themselves: and, because the pressure upon any part of a confined fluid, is propagated tothe whole of it, in every di- rection; so, the weight of the atmosphere, resting on the edges of this fluid plate, tends as much, by the interposition of the same, te buoy up, and force assunder, the surfaces resting on it, as it does to compress together these surfaces, by its action on themselves; and exerts itself equally to prevent ‘their approach on one side, as their recession on the other. I conceive the agency of these forces to be this : that the plate of water is so strongly attracted by she surfaces nearly in con- tact, as to be kept from running off, and has its outer edge exposed to the weight of the air ; whose pressure is thus com- municated to all the particles of the water, and, by its me- diation, to the contiguous surfaces of the mirror and polisher. aind, though all these are really compressed together, by the surrounding atmosphere, yet I conceive that this does not hinder their gradual separation from being effected: because, as fastas that separation takes place on any side, the air and waterrush in between the surfaces, to fill up the vacuity, as REFLECTING TELESCOPE. 49 it is formed ;_and no farther resistance arises to their disjunc- ee tion, than what is owing to the viscidity of the fluid interposed, cee and to the force of cohesion ; which latter acts, in this case, process of po- quite different from any external force of compression; and [ishing mirrors. prevails, as I apprehend, to a small distance from the surface, diminishing in the ratio of some high power of that distance. * And hence I suppose, that the weight of the atmosphere is wholly inefficient, in keeping the mirror and polisher in mutual coherence, when any liquor of perfect fluidity is between them; and that the force of cohesion acts alone to this effect. Ac- cordingly, it is found, that, when the polisher is somuch wet- ted with water, that there is formed a continuous plate of this fluid between it and the mirror, an additional force, sufficient to squeeze out the water interposed, becomes requisite to bring the surfaces into actual contact, and to produce so much friction between them, as will serve to wear down and polish the metal; which process will be found, in these circumstan- es, to advance very slowly and irregularly. And, on the contrary, when so little water is applied to the polisher, that it is only made damp, and scarce wetted, (i. e. when there is net a coutinuous body of liquid interposed between it and the mirror,) then its contact with the metal will be so intimate and strong, that the latter will polish very quickly. For then their surfaces approach within the sphere of the attraction of cohe- sion: insomuch that, if all moisture were suffered to evaporate, the mirror and polisher would cohere so firmly, as not to permit any friction, oreven a separation of their surfaces, and the polisher would be destroyed; for then the weight of the atmos- phere, also, would be superadded, when no fluid is interposed : * If it were supposed, that the force of cohesion is confined to the surface of bodies, and acts only in the state of actual contact; it would be hard to conceive, why a drop of liquor should ascend, in 2 conical glass-pipe, whose narrow end was elevated: since the drop ought, on this supposition, to be attracted as much by the surface below, as by that above it: and its weight ought to make it descend ; and there would be nothing to make it spread beyond the space of contact which it occupies: whereas if the attraction extends, directly in right lines, to a distance from the - sides of the pipe, the composition of their forces ought to make the drop ascend, and spread itself in its caurse, as it happens in fact. Vor. XVI.—Jan- 1807.—No. 65. E ‘50 REFLECTING TELESCOPE: ~ all which shew that their cohesion, when a fluid does intervene, Hard pitch will not give a good figure, nor will it receive the po- lishing powder. is not caused by the pressure of the atmosphere. Agreeably to this, the sagacious Newton directs, that, towards the end of the operation, no more moisture should be applied to the polisher, than what it will contract, from the operator’s breathing on it. Indeed, a person, who has formed a just conception of his genius and intense application of mind and considered the hints and precepts he has given in this work, can hardly doubt, that he could, and, perhaps, would, have furnished a theory of the rulesand method of this whole process had he not imagined it would, at that time, be regarded as a matter of too little importance, to deserve so minute an ex- planation, which must be necessarily prolix, and seem un- worthy of him, who was occupied in more sublime speculations. From this it follows, that, when the pitch is of unyielding hardness, it will not, in any mode of polishing, communicate to the mirror the desired shape, if the dust worn from the mirror, does notalter the shape of the polisher. And, as this seems not likely to happen, so I was not surprised, that my efforts, to effect the desired figuration of the mirror, by using very hard and refractory pitch, failed of success. And there is this inconvenience, moreover, in the use of such pitch, viz. ‘that it makes so great resistance to the sinking and bedding of the polishing powder in it that the particles of the powder, however fine it may be, will, on any fresh appli- cation of it, or when any grains of it are accidentally dislodged from the pitch, roll about loose on the polisher, and scratch the face of the mirror, so as to destroy the polish before given ; thus making any fresh application of the powder inadmissible, unless the pitch were to be softened by heating it, which would destroy its former figure, and render the operation uncertain and tedious. It was to allow the polishing powder to fix itself, without rolling loose on the polisher, and to suffer all its parti- cles, however different in size, to sink init, so as to form an even surface, that Sir Isaac Newton, in his sagacity, employed a coat of pitch on the polisher, as a soft substance, that would _ yield to the powder, when impressed on it by the mirror, and not afford such resistance, as to make it fret the face of the metal; andalso asa substance endued with another property equally necessary, that of being perfectly unelastic. For ao elastic substance will ever communicate an exquisite polish to REFLECTING TELESCOPE. 3 metallic speculum, though it would to glass, crystal, or jewels ; because no metal can be cast, perfectly free from small pores: and any elastic substance, if employed to polish it, would insinuate itself, together with the polishing powder, into these pores, and wear down their edges in such a manner, as to convert every pore into a long furrow or cavity: which would occasion the destruction of the whole surface of the metal, as was truly observed by Sir Isaac Newton. And thus it appears, that; to make the pitch too hard and refractory, would be to destroy every property in .it, which renders it eligible i in this operation. 51 If the positions, before stated; be well founded, it seems 0 The polisher follow, that the desired change i in the mirror, from a spheri- cal to a conoidal figure, can only be effected, by a change in the shape of the polisher, gradually accommodating itself to the alteration, produced in that of the mirror, during the process of polishing. Nor, indeed, can it well be conceived, how the mirror could alter its spherical form, if that of the polisher remained unaltered; fora conoid could never, in the usual way, and without a partial separation of the surfaces in contact, be polished on a segment ofa sphere, nor even on that of a conoid, if, during the friction of their surfaces, the center, or vertex of the one, were to be moved to any considerable distance from that of the other. So that the strokes, in polishing, must never ultimately be carried so far as to remove the center of the mirror to too great a distance from that of the polisher ; even though its surface were so hard, as to preserve its figure unaltered by the pressure of the mirror.* * For the several reasons above mentioned, I am inclined to think, it will be very difficult to discover a method, different from that here explained, of communicating, at the same time, a perfect figure and polish to a speculum. Itisplain, that New- ton could think of no better; though | imagine that, in this in- stance, he tried his inventive powers with those of Des Cartes, who had published a method (in theory elegantly geometrical) of figuring optic glasses. And I cannot dissent from those, who think this was the method employed by Mr. Short, with such success, in figuring the mirrors of his telescopes; [ mean a con- duct in the operation, sagaciously adapted to the properties of the pitchy coating of the polisher. It must be obvious to the reader, that none of the remarks or directions, contained in this essay, can be meant to apply direct- must chahge its figure while that ofthe mits _ ror changes. 52 The pitch should be 2 little harder REFLECTING TELESCOPE. Agreeable to these positions, I found, in my trials of po- lishing mirrors in the common way, by straight or round than cof—mon. Strokes of the mirror, on the polisher, that the operation was more easy and successful, when I used pitch of nearly the common consistence, than when I employed such as was made very hard, by long boiling it, or by the addition of much resin. Such softer pitch will admit more than one ap-~ plication of the polishing powder, without scratching the metal, or spoiling its previous polish; by which means, the process will be moge expeditious. It will instantly accom- modate itself to the successive alterations in the form of the. metal; as this, by wearing down towards its edges, gradually changes from a spherical, to a conoidal shape: and it will promote this effect, by opposing a greater resistance to the ly to the polishing any speculum, whose magnitude is too great, to admit of being moved ona polisher, of equal size with itself. Where the friction, and force of cohesion, of such large surfaces in contact, and the weight of the mirror, exceed the motive power that can be employed, a polisher, of less extent than the whole surface of the mirror, must be applied, to traverse, in suc- cession, the several parts of it; and the motion-must be given, not to the mirror, but fo the polisher. Instruments of far less enormous magnitude than Doctor Herschell’s great telescope, are. sui generis, and require particular methods of polishing the mir- ror adapted to their size. For such, no person should presume to propose any method, which he has not approved in practice: though, as the general principles here Jaid down, are, with due accommodation, applicable to a polisher of any shape or extent of surface ; it should seem, that, if such great mirrors could be po- lished by a regular and uniform motion, their polishers might be made such segments or sectors, &c. of the area of each respective mirror, and of such breadths in different ports ; and the furrows, made in the coating of pitch thereon, of such number, proximity, and depth, as to afford, in the tract of the motion of each part, a degree of pressure and friction, reciprocally proportional to the degree of curvature, proper to each concentric zone of the mirroy’s surface ; which would tend to produce the desired figure, so-far as a polisher, covered with pitch, could be made instrumental to this purpose. For though the size and shape of the polisher were ta: remain unaltered, yetits resistence and abrading power might be considerably modified, by varying the number and depth of the furrows, made in the pitch which covers it. And the effect of a process, thus conducted, will be commensurate to the time it is ‘persisted in, REFLECTING TELESCOPE. 53 metal, and greater friction towards its extremities, when its previous disposition on the polisher has been judiciously pros vided, in the manner before explained. But, to fulfil these intentions effectually, a certain kind of Desdiption of motion, of the mirror on the polisher, must be carefully ob- Lhe Sek served, during the operation: for, as the softer pitch will proper for give continually yield, and sink under the pressure of the metal ; #78 the Aguree so, the form of the polisher, degenerating in every shook; ‘: must be recovered, and preserved correct. According to the principles before laid down, the face of the polisher must be considerably larger than that of the metal, in order to afford a greater resistance to the speculum, towards its extremities : so that, as the metal covers only a part of the polisher, if the former were to be confined in its motion, the pitch, sinking under it, would expand itself laterally, and become heaped up suddenly, around the tract of the mirror’s pressure 5 which must, therefore, to obviate this, be so conducted, as to traverse, in quick and regular succession, every part of the polisher, in order to recover the regularity of its figure as fast as it becomes vitiated. And this is effected in two ways: either by enlarged circular strokes of the metal, brought. considerably beyond the edges of the polisher, in order to repress, towards the center, the pitch, which had become raised near its edges, or by straight diametrical strokes, across its surface, in every direction siecevively either of which. will tend to preserve the figure of the polisher, and, conse- quently, of the mirror, nearly spherical. As, however, a spherical figure is not that which is ultimately intended, so these modes of conducting the process are to be pursued only till the mirror has acquired a sufficient polish, and a figure nearly spherical: and then, in order to give it a parabolic or hyperbolic shape, the motion of the mirror, on the polisher, should be such, as that the center of it may describe a spiral line round the center of the polisher, by enlarging the cir- cular strokes, till the edge of the mirror arrives at the edge ef the polisher; and then contracting the motion gra- dually, till the mirror returns to the center, in the same spiral course. By which means, any sudden and irregular eleva- tion of the pitch, beyond the place of the mirror, will be prevented ; while, at the same time, it will become regularly elevated, from the outer edge, i in the form of-a conoid, and E3 Method of tak- . ing away part of the face of the polisher. REFLECTING TELESCOPE, thus be adapted for communicating the same figure to the mirror. I have been led to adopt and practise this method of poe lishing mirrors, by the train of reflections and reasoning herein described, and with sufficient success, for its unre- served recommendation. In one particular, it corresponds with the method published by Mr, Mudge, in the Philoso- phical Transactions, viz. in the direction of the motion used in polishing the mirror. But this seems to have been pre- scribed by him, without any respect to the properties of mobility and inequality of friction, in the pitchy coating of the polisher ; which things he has not noticed. And yet, as any sort of motion, without a proper regard and adaptation to the qualities of the pitch, would be ineffectual, it is here attempted to supply that defect; because no method can be rightly pursued in practice, nor its success be uniform, nor any: figure already given to the mirror be altered, if those artists, who would follow it, are ignorant of the principles and agency on which it is really founded. For, in every process of so subtil and delicate a nature, some untoward accidents and circumstances must occur, which will grow above the control and correction of any person, who is not aware of the secret causes from whence they arise. In such cases, the practice will be as imperfect as the theory is. It has been above explained, how the middle zone, or tract of the polisher, equidistant from its inner and outer edge, when there is a void at the center, will oppose a greater de- gree of friction to the mirror, than the other parts of the polisher. And, to prevent the unequal wearing of the mir- ror, by the increased action of this zone, it will be~- proper, that, agreeable to the methods of prevention of this effect before mentioned, there should be circular furrows indented in the pitch within this zone, more or fewer, according to the size of the mirror, and the designed degree of its curvature ; in order that the pitch may subside into the furrows, and thus the resistance and friction in that tract may be diminished. This will be very easily accomplished, by putting. the po- lisher on the arbor of a lathe, and cutting out some of the pitch in circular grooves, with a small sharp and concave turning chisel, wetted with water, in which some soap has been dissolved. And this may be performed and repeated, REFLECTING TELESCOPE, 54 if necessary, without any injury to the surface of the po- lisher, if it be previously wetted, to prevent the splinters of the pitch from sticking to it; which may be washed off, by a soft brush or pencil, from the polisher, it being immersed in water. _ Since, in the Gregorian telescope, the defect of figure or 13, better that curvature, from that of a conoid, in one of the mirrors, may the small spe= be compensated by a conirary. curvature in the other; and poate since, in either of the mirrors, whose breadth is given, the degree of variation in its figure, from that of a sphere, ought to be so much the greater, as its focus, or radius of curvature, is shorter ; it will, on this account, be far more difficult, to effect a proper figure of the small mirror in this telescope, than of the large one; because the former must bea greater segment of the sphere, than the latter. _ For which reason, instead of making the one. of an elliptic, and the other of a parabolic form, I imagine it would (with the exceptions before mentioned) be more proper to rest content with a sphe- rical form in the little mirror, (by which means, several of these Jatter, being fastened, with cement, beside each other, on the same handle, might be accurately and easily ground and polished together, on one tool and polisher, made suffi- ciently large); and to employ the great efforts on the large mirror, in rendering it of an hyperbolic form ; which is not at all more difficult than it is to make it parabolic: for, on ac- count. of the small extent of surface of the little mirror, it is very difficult to govern and regulate its motion and pressure, so as to communicate to it any certain figure, if polished by itself singly ; as it must, be, when it is to be of any other than a spherical form. Yet, even this may, by an intelligent and dexterous artist, be accomplished, to a considerable degree of ee pe perfection, in the manner above mentionned, as I have re- may be given, peatedly experienced; though the process is much more easy and certain, in figuring the large mirror (under that limitation ofits size before intimated): for the greater the surface to be polished is, the less will any inequality of pressure, in the operation, alter the form of the mirror, or the polisher; such inequality, being a part only of the motive force employed ; and the more extensive the surface is, the less proportion does the motive force bear to the force of cohesion, which tends to preserve an uniformity of pressure in the mirror, and of figure 56 A larger spe- culum is most easily figured. REFLECTING TELESCOPE. in the polisher. And I believe it is on this account, rather than that of preventing aberrations of the rays of light, froma supposed spherical shape of the mirrors, that telescopes of greater apertures and foci are more accurate ; the larger sur- faces of their mirrors having atendency, during the opetation of polishing, to preserve the regularity of their figure. For, let the aperture of a telescope be ever so large, with respect to the focus of the great mirror; yet when the object is very remote, the central part of the field of view (the rays of light from which are parallel to the axis,) ought to appear perfectly distinct, if the metals were wrought up to the correct figure of conoids: and the vulgar doctrine of aberrations, which relate only to spheres, is entirely inapplicable. The only standard, for the measures of the apertures and foci, is the degree of ingenuity in the workman, who fabricates the in- sirument. There are many defects in figure, besides a sphe- rical form of the mirrors; and it happens but too frequently, that a telescope is very indistinct, froma bad figure of them, though that figure is the nearest to a conoid of any regular curve: for this is often the case, when the central, the ex+ treme, and the intermediate parts of the mirror, successively and separately exposed to receive the light from the object, appear to have the same focus. And this mostly occurs, when the mirrors are small ; certain tracts, or portions of their sur- face, being more worn down, by thé grinding or polishing, than others, arising from the difficulty of preserving an uniform pressure during the operation, and, consequently, a regular figure of the polisher. Another method, different from that now described, of communicating to mirrors a parabolic form, has been discove- red by the late Rev. M. Edwards, and published in the Nau- tical Almanack, for the year 1787. He recommends, to make the edge of the polisher the periphery of an ellipse; so that the face or area of it may not be round, but oval :. the shortest diameter of the ellipse being equal to that of the mirror; and its longest diameter to be to the shortest, as 10 to 9. And he affirms, that a mirtor, finished on such a polisher, will prove to be of a parabolic form; if the process be conducted, by employing, throughout the operation, straight strokes of the mirror, diametrically acros the polisher, in every direction. Now in the method recommended by M. Mudge, whatever REFLECTING TELESCOPE. 57 kind of motion be used, in bringing the face of the mirror toa polish, the parabolic form is directed to be acquired, only by a circular motion in polishing: Mr. Mudge having declared, that the effect of such straight strokes would be, to produce no other than a correct spherical figure in the mirror. Here, then, are opposite motions, and declared to be productive of con- trary effects, proposed by two very intelligent, artists, with a view of promoting the same effect; the only difference being this, that, in the onecase, the face of the polisher is supposed to be round, and in the other, oval: a difference that a person may well imagine to be (as it really is) of very little impor- tance ; and he may be easily led to suspect, that the presumed effect of either mode is only imaginary ; thata spherical figure of the mirror has been mistaken for a parabolical one: or that, if the latter has been produced, it may have been, not by method, but by chance; and he may naturally distrust any rule or method advanced for this purpose. Thus, when dif- ferent instructions are given, by different persons, without any reasons or explanations assigned as the foundation of them, the whole rests on authority; authorities clash, and then the worst may be followed, or all be rejected; and, for want of a guide, an uncertain practice be adopted. It is for this reason, T have judged it necessary here, (as also in former essays, made public,) to be very minute, in attempting to investigate the grounds of any method to be pursued, and the principles of ac- tion, in the operation of the instruments I am treating of. I have made a trial of the method of polishing, proposed by commendae Mr. Edwards, with attention to all the circumstances, which he tion ef the me- directs to be observed ; and, from the result, | have reason to Spa ag = believe, that his method is a good one, and will, if judiciously ear applied, produce as correct a figure of the mirror, as, perhaps, any other, yet made public, But, whoever will attentively in- vestigate the nature of the operation, will, I think, cease to wonder, that modes of conducting it, seemingly so dissimilar, tend to the same effect , and perceive, that the contrariety is Not real, but merely apparent *. For, in either method, it is not the direction of the motion * In the methods of figuring the mirrors, published by Mr. Mudge, and by Mr. Edwards, it is stated by Mr. Mudge, that he frequently, during the process, applied to the polisher a concave 3S REFLECTING TELESCOPE. The radial and employed, nor the shape of the area of the polisher, which, ins the spiral stroke com- pared. Poubt which may be pre- ferable. reality, produces a conoidal form in the mirror; but a gradual alteration in the curvature of the face of the polisher, by yield- ing of the pitch, under the pressure. And, therefore, when any part of the area of the polisher, whether it be round or oval, is more extended than that of the mirror; the pitch, moving laterally, will become elevated, and its curvature les- sened, in that part, Sothat, ina polisher of oval shape, whose conjugate diameter is equal to that of the mirror, the pitch will ascend and accumulate, in the patt, which lies without the circular area of the mirror, inscribed in the ellipse. The exe tremities of the mirror will, therefore, be worn down, when each part of them is made in rotation, by straight strokes across the polisher, in the transverse diameter of the ellipse, to tra- verse that part of it, which circumscribes the circle; and, by such strokes made twice, directly in that diameter, and oftener obliquely, in each rotation of the mirror, as the operator moves round the polisher, during the process, the regular shape of the polisher is preserved. But it is easy to conceive, that the same effects would follow, though the polishing.. were;,con- ducted, not by straight strokes across, but by round strokes, in a spiral direction, as ahove mentioned, And I am doubtful, to which of these motions the preference should be given; or whether they ought not to be interchangeably used, to pro- duce the most elaborate form in the mirror; asalso, whether this method, of Mr. Edwards, 1s better than the former, by Mr. Mudge, above described. For I have been deprived of lei- sure ee opportunity (by the war, and public troubles, during the French invasion and the rebellion ; in which, most, of my instruments, for such purposes, were lost, in the plunder and tool, which he calls a bruiser; by, which he must have preserved or recovered, the figure of the polisher, and, consequently, of the mirror, that otherwise must have become vitiated, by the unequal resistance of the pitch; and Mr. Edwards made furrows in the coating of pitch, or his polishers. It is to these circumstances, and not to the direction of the motion employed, or the elliptie area of the polisher, that, I can think, was owing to the success, attendant on their methods: the bruiser being necessary, to supply the defect of furrows in the pitch; and the oval form not essential, when there were such, duly disposed, and also the pone of. proper size, &c, as here directed, -REFLECTING TELESCOPE. 59 destruction of my house,) to prosecute the experiments, which might have enabled me to speak with more precision ; and which I would have done, from the desire I had, to contribute to the perfection of so noble an instrument as the neflecting te- lescope, I know, that both methods will, in judicious practice, pro- Both may suc ; duce the desired effect ; but this effect will be limited, in de- eeed. gree of perfection, and sometimes frustrated, when the causes and circumstances, that operate in it, are unknown, In either method, and with a polisher of round or oval shape, it is indis- pensably necessary, that there should be furrows made in the coating of pitch, (to allow it to subside, in regular gradation, from the middle to the edges,) by indenting it, either in squares, as is usually done, or in circular channels; both which must be renewed, as they become filled up and obliterated; which will always happen soonest in the middle zone or tract of the polisher, between the center and other edge, whether the fur- rows be circular or longitudinal: and, if this be not done, the regularity of curvature would not be preserved in the mirror, or the polisher. But, since there is no obstacle to the subsidence of the pitch, near its outer edge, and its inner edge, when there is a void space at the center, I believe the furrows ought not to be made there, but in the intermediate space only. And I am of opinion that it is, from the judicious dis- —put these position of these furrows, the most correct shape of the mirror must be fur- is to be acquired, whether the polisher be round or oval, or pinche: i the pitch hard or soft : for I found, that, in Mr. Edwards’s me- thod, and with pitch, even as hard as he recommends, the channels made in it were, towards the end of the operation, nearly obliterated, in the middle zone of the polisher. But this will not happen so soon, nor so dangerously, with hard as with soft pitch ; nor will the correction of the impaired shape of the polisher be so difficult, when it is ofan oval, as when of a circular area: there being, in the former case, less of irregue Jar surface in it, to be reduced; anda more steady, uniform, and simple motion, in grinding, may be pursued; which, as it will admit of a less degree of expertness and sagacity in the ar- tificer, will be more commonly attended with eminent suc- cess * (To be Continued.) sali ahi that a polisher, whose area is of an oval form, would be better adapted to the formation of a parabolic, than an CIRCULATION OF THE SAP. sie . . sta VI. _ On the inverted Action of the alburnous Vessels of Trees. By Theory de- duced from faets, by the author: that the sap circu- Yates through the leaves and deseends through the bark. Tuomas Anprew Knicur, Esq. F.R.S. From the Phi- losophical Transactions, 1806. I HAVE endeavoured to prove, in several Memoirs* which you have done me the honour to lay before the Royal Society, that the fluid by which the various parts (that are annually added to trees, and herbaceous plants whose organization is similar to that of trees}, are generated, has previously circu- Jated through their leaves f either in the same, or preceding hyperbolic curvature, in the speculum ; and that the latter will be most correctly formed by a polisher, whose area is nearly circular. For, in order to make the speculum hyperbolic, the longest dia- meter of the oval polisher must be considerably greater than the shortest one, 1. e. than the breadth of the mirror: as will be evi- dent, from a consideration of the circumstances I have endea+ youred to explain. And, asthe mirror must be carried, by the strokes in polishing, to the extreme verge of the polisher; so, when it is to traverse it, in the direction of its longest diameter, it will have its center or vértex removed too far from that of the po- lisher, to acquire from it a true conoidal figure. Either, therefore, the face of the polisher should be round; or, if it be oval, it ought to be rendered a less eccentric ellipse, by having its shortest diameter greater than that ef the mirror, which will allow the ex tent of the polisher to be reduced, by contracting proportionably its tranverse diameter; i.e. it must be brought nearer to a circular figure. For the objection, mentioned by Mr. Edwards, to a round shape of the polisher, when it is to be considerably larger than the mirror, viz. ‘‘ that it makes the latter perpetually into a “ segment of a larger sphere, and by no means of goad figure,” I apprehend to have chiefly arisen, from an omission, in those whe tried it, to make furrows in the pitch, in the proper tract, on the surface of the polisher; which, if it had been done, would have produced, not a spherical, but a canoidal figure. ’ * In the Phil. Trans. for 1801, 1803, 1804, and 1805. + During the circulation of the sap through the eaves, a transparent fluid is emitted, in the night, from pores situated on their edges ; and on evaporating this liquid obtained from very luxuriant plants of the vine, I found a very large residuum CIRCULATION OF THE SAP. ” ee season, and subsequently descended through their bark ; and after having repeated every experiment that occurred to me, from which I suspected an unfavourable result, 1 am not in possession of a single fact which is not perfectly consistent with the theory I have advanced. There is, however, one circumstance stated by Hales and Apparent ob- Du Hamel, which appears strongly to militate against my 8 ore, hypothesis ; and as that circumstance probably induced Hales Hales and to deny altogether the existence of circulation im plants, and Du Hamel. Du Hamel to speak less decisively in favour of it than he pos- sibly might otherwise have done, I am anxious to reconcile the statements of these great naturalists, (which I acknowledge to be perfectly correct,) with the statements and opinions I have on former occasions commuicated to you. Both Hales and Du Hamel have proved, that when two Th4 the stem circular incisions through the bark, round the stem of a tree, below an an- apiaicbiciat cr Seinll :distnee Gow ‘cach other, and when the spl aphualy bark between these incisions is wholly taken away, that por- and grows, tion of the stem which is below the incisions through the bark ‘vsh lite. continues to live, and in some degree to increase in size, though much more slowly than the parts abeve the incisions, They have also observed that a small elevated ridge (bowrrelet) is formed round the lower lip of the wound in the bark, which makes some slight advances to meet the bark and wood pro- jected, in much large quantity, from the opposite, or upper lip of the wound. I have endeavoured, in a former ictal, * to explain the Explanation of cause why some portion of growth takes place belo: inci- this fact. sions through the bark, by supposing that a small part of the true sap, descending from the leaves, escapes downwards through the porous substance of the alburnum. Several facts stated by Hales seems favourable to this supposition; and the existence of a power in the alburnum to carry the sap in different directions, is proved in the growth of inverted cut- tings of different species of trees.t But I have derived so to remain, which was similar in external appearance to carbonate of lime. It must, however, have been evidently a very different substance from the very large portion, which the water held in solution. I do not know that this substance has been analyzed, gt noticed by any naturalist. * Phil, Trans. for 1803. + Ibid. for 1904. 62 CIRCULATION OF THE SAP. many advantages, both as a gardener and farmer, (particdlarly in the management of fruit and forest trees,) from the expe- riments which have been the subject of my former memoirs, that I am confident much public benefit might be derived from an intimate acquaintance with the use and office of the various organs of plants; and thence feel anxious to adduce facts to prove that the conclusions I have drawn are not inconsistent with the facts stated by my great predecessors. ‘The first mo- It has been acknowledged, I believe, by every naturalist tion of the true who has written on the subject, (and the fact is indeed too i Obvious to be controverted,) that the matter which enters into downwards the composition of the radicles of germinating seeds existed previously in their cotyledons ; and as the radicles encrease only in length by parts successively added to their apices, or points most distant from their cotyledons, it follows of neces- sity that the first motion of the true sap, as this period, is downwards. And as no alburnous tubes exist in the radicles of germinating seeds during the earlier periods of their growth, the sap in its descent must either pass through the bark, or the medulla. But the medulla does not apparently contain any vessels calculated to carry the descending sap; whilst —through the the cortical vessels are, during this period, much distended and bark. full of moisture: and as the medulla certainly does not carry any fluid in stems or branches of more than one year old, it can scarcely be suspected that it, at any period, conveys the whole current of the descending sap. Cortical vessels AS the leaves grow, and enter on their office, cortical ves- from the bases sels, in every respect apparently similar to those which des- of the leaves, by which the Cended from the cotyledons, are found to descend from the sap descend. _ bases of the leaves ; and there appears no reason, with whieh I am acquainted, to suspect that both do not carry a similar fluid, and that the course of this fluid is, in the first instance, always towards the roots. The ascending The ascending sap, on the contrary, rises wholly through sap passes the alburnum and central vessels; for the destruction of a - Saeco at portion of the bark, in a circle round the tree, does not imme- central vessels. diately in the slightest degree check the growth of its leaves” and branches: but the alburnous vessels appear, from the experiments 1 have related in a former paper,* and from those * Phil, Trans, for 1804. CIRCULATION’ OF THE SAP. 63 t shall now proceed to relate, to be also capable of an inverted action, when that becomes necessary to preserve the existence of the plant. As soon as the leaves of the oak weré nearly full grown Experiments in the last spring, I selected in several instances two poles of rae athe the same age, and springing from the same roots in a coppice, which had been felled about six years preceding ; and making two circular incisions at the distance of three inches from each other through the bark of one of the poles on each stool, I destroyed the bark between the incisions, and thus cut off the stem and roots, through the bark. Much growth, as usual, took place above the space from which the bark had been taken off, and very little below it. Examining the state of the experiment in the succeeding winter, I found it had not succeeded according to my hopes: for a portion of the alburnum, in almost every instance, was lifeless, and almost dry, to a considerable distance below the space from which the bark had been removed. In one in- stance the whole of it was, however, perfectly alive; and in this I found the specific gravity of the wood above the decor- ticated space to be 114, and below it 111; and the wood of the unmutilated pole at the same distance from the ground to be 112, each being weighed as soon as it was detached from the root. Had the true sap in this‘instance wholly stagnated above the decorticated space, the specific gravity of the wood there ought to have been, according to the result of former experi- ments,* comparatively much greater: but I do not wish to draw any conclusion from a single experiment; and indeed I see very considerable difficulty in obtaining any very satis- factory, or decisive facts from any experiments on plants, in this case, in which the same roots and stems collect and convey the sap during the spring and summer, and retain, within themselves, that which is, during the autumn and winter, reserved to form new organs of assimilation in the succeeding spring. In the tuberous-rooted plants, the roots Experiment and stems which collect and convey the sap in one season, va Deh Be) and those in which it is deposited and reserved for the suc- ceeding season, are perfectly distinct organs; and from one * Phil. Trans, for 1805, 64 CIRCULATION OF THE SAP. vof these; the potatoe, I obtained more interesting and decisive results.’ 38 My principal object was to prove that a fluid descends from the leaves anel stem to form the tuberous roots of this plant; and that this fluid will in part escape down the al- ‘burnous substance of the stem when the continuity of the cortical vessels is intetrupted: but I had also another object in view. ; ey st The early va- Every gardener knows that early varieties of the potatoe rieties.afford. never afford either blossoms or seeds; and I attributed this neither blos- ees Le a . . soms nor seeds, peculiarity to privation of nutriment, owing to the tubers being ‘because the — formed preternaturally early, and thence drawing off that por- ca ae tion of the true sap, which in the ordinary course of nature true sap which is employed in the formation and nutrition ef blossoms and might have seeds formed them. j i 3 Cuttings of the 2 therefore planted, in the last spring, some cuttings of a potatoe ma- very early variety of the potatoe, which had never been ee e ‘© known to blossom, in garden pots, having heaped the mould tubers, as high as I could above the level of the pot, and planted the portion of the root nearly at the top of it. When the plants had grown a few inches high, they were secured to strong sticks, which had been fixed erect in the pots for that pur- pose, and the mould was then washed away from the base of their stems by a strong current of water. Each plant was now suspended in air, and had no communication with the soil in the. pots, except by its fibrous roots, and as these are perfectly distinct organs from the runners which generate and feed the tuberous roots, I could readily prevent. the Taegu formation of them. Efforts were soon made by every plant blossoms and t& generate runners and tuberous roots; but these were fruits. destroyed as soon.as they became perceptible. An increased luxuriance of growth now became visible in every plant; numerous: blossoms were emitted, and every blossom afforded fruit. 2" The redundant Conceiving, howeyer, that a small part only of the true sap was made sap would. be expended in the production of blossoms and on vided ped seeds, I was anxious to discover what use nature would make instead of the of that which remained, and I therefore took effectual means oe to. prevent the formation of tubers on any part of the plants, except the extremities of the lateral branches, those being the points most distant from the earth, in which the tubers. CIRCULATION OF THE SAP. 65 are naturally deposited. . After an ineffective struggte of a few weeks, the plants became perfectly obedient’ to my wishes, and formed their tubers precisely in the places I had assigned them. Many of ‘the joints of the plants during the experi- ment became enlarged and turgid; and I am much inclined to believe, that if I had totally prevented the formation of regular tubers, these joints would have acquired an organiza- tion capable of retaining life, and of affording plants in the succeeding spring. I had another variety of the potatoe, which grew with Another expes great luxuriance, and afforded many lateral branches; and a nee just at that period, when I had ascertained the first com- mencing formation of the tubers beneath the soil, I nearly detached many of these lateral branches from the principal stems, letting them remain suspended by such a portion only of alburnous and cortical fibres and vessels as were sufficient to preserve life. In this position I conceived that if their leaves and. stems contained any unemployed true sap, it could not readily find its way to the tuberous roots, its passage being obstructed by the rupture of the vessels, and by gravi- tation; and I had soon the pleasure to see that, instead-of re~ turning down the principal stem into the ground, it remained and formed small tubers at the base of the leaves of the de- pending branches. The preceding facts are, I think, sufficient to prove that the gence the tu- fluid, from which the tuberous root of the potatoe, when bers are form- * growing beneath the soil, derives its component matter, exists mnt zag pail previously either in the stems or leaves; and that it subse- the stems or quently descends into the earth: and as the cortical vessels, Wt a during every period of the growth of the tuber, are filled with the true sap of the plant, and as these vessels extend into the runners, which carry nutriment to the tuber, and in other instances evidently convey the true sap downwards, there appears little reason to doubt that through these vessels the tuber is naturally fed. _ To ascertain, therefore, whether the tubers would cone groyip of the tinue to be fed when the passage of the true sap down the tubers imped- cortical yessels was interrupted, I removed a portion of bark ll Ma a of the width of five lines, and extending round the stems of descending _ several plants of the potatoe, close to the surface of the %#P: ground, soon after that period when the tubers were first Vo L. XVI.—Jan. 1807,—No. 65. ¥ 66. CIRCULATION OF THE SAP. formed. ... The, plants continued some time in health, and during that. period the tubérs continued to grow, deriving their nutriment, as I conclude, from the leaves, by an inverted action. of the alburnous. vessels. The tubers, however, by - no,means attained their natural size, partly owing to the’ de- clining-health of the plant, and partly to the stagnation of'a _ portion.of the true sap above the decorticated space. Probability that. The fluid contained in the leaf has not, however, 'been- ge 2 arcs proved, in any of the preceding experiments, to’ pass down- the alburnum wards through the decorticated space, and to be: subsequently - where the — discharged into the bark below it: but I have proved with Pe i amputated branches of different species of trees, that the water. which their leaves absorb, when immersed in that. fluid, will be carried downwards by the alburnum, and con}: veyed into a portion. of bark below the decorticated spate >. and that the insulated bark will be preserved alive and moist: during several days ;* and. if. the moisture. absorbed» by a leaf can: be thus transferred, it appears extremely probable: that the true sap will pass through the same channel. ‘This power in the alburnum to carry fluids in different directions: probably answers very important purposes in hot climates, ° where the dews -are abundant and the soil very. dry; for. the moisture the dews afford may thus be conveyed: to» the extremities of the roots: and Hales has proved that the leaves absorb most when placed in humid air;.:and that the sap descends, either through the bark or ialdonilen aes ing the night. i This invertea. Jf the inverted action of the alburnous aceaie in: njthe blend action of the corticated space be admitted, it is not difficult to explain the. pam Fag Cause why some degree of growth takes place below such in the experi- decorticated spaces on the stems of trees; and why a small: mens Oat portion of bark and wood is generated on the lower lip of “the wound. ..A considerable. portion of the descending true) sap certainly. stagnates ‘above the wound, and of that .which y>. “escapes, into the bark..below it, the greater: part'is) probably: carried towards; pend: into, the roots; where it preserves’ life,’ # This, eapesincat sie not succeed till the leaf has attained © its fyll-growth and \maturity,;and the alburnum of the nquaat shivot. its perfect organization. Gi 1 ee Per ays _ > i ae = CIRCULATION OF THE SAP- 67 and: occasions ‘somedegree’ of growth to take place. But asmall portion of that fluid will -be “carried upwards by capillary attraction, ‘between the bark and the alburnum, — exclusive of. the immediate action of the latter substance, and: the. whole ‘of this will stagnate the lower lip of the wound;. where I conceive it generates the small portion of wood and bark, which nate and Du Hamel have de- scribed. I wath scarcely have dsonghit an-account t of the preceding Interesting experiments worth sending to you, but that many of the eee conclusions I have drawn in my former memoirs appear, at oe ical first view, almost incompatible with the facts stated by Hales tion of the fir. and» Du. Hamel, and that I had» one fact to communicate relative to the effects produced by the stagnation of the descending sap of resinous trees, which appeared to lead to important consequences. I have in my possession a piece of a fir-tree, from which a portion of bark, extending round its ~ whole stem, -had been taken off several years before the tree: was felled ; and of this portion of wood one part grew above, andthe other» below, the decorticated space. Conceiving that, according to the theory I am endeavouring to support, The wood the wood above the decorticated space ought to be much aa pier de- heavier than that below it, owing to the stagnation of the space is much descending sap, I ascertained the specific gravity of both denser. _ kinds, taking a wedge of each, as nearly of the same form as I could obtain, and I found the difference greatly more than I had anticipated, the specific gravity of the wood above. the decorticated space being 0.590, and of that below only 0,491 : and having steeped pieces of each, which weighed a hundred grains, during twelve hours in water, | found the lat- ter had absorbed 69 grains, and the former only 51. The increased solidity of the wood above the decorticated Whence consi- space, in this instance, must, I conceive have arisen from the ao stagnation of the true sap in its descent from the leaves ; and derived in therefore in felling firs, or other resinous trees, considerable felling: advantages may be expected from stripping off a portion of their bark all round their trunks, close to the surface of the ground, about the end of May or beginning of June, in the summer preceding the autumn in which they are-to be felled. For much of the resinous matter contained in the roots of _ these is probably carried up by the ascending sap in the E'? 68 The increased solidity is not confined merely to the Vicinity of the decorticated space. CIRCULATION OF THE SAP. spring, and the return of a large portion of this matter to the roots would probably be prevented :* the timber I have, however, very little doubt would be much improved by standing a second year, and being then felled in the autumn; but some loss would be sustained owing to the slow growth of the trees in the second summer. The alburnum of other trees might probably be rendered more solid and durable by the same process: but the descending sap of these, being of a more fluid consistence than that of the resinous tribe, would escape through the decorticated space into the st in ne larger quantity. It may be suspected that the increased solidity of the wood in the fir-tree 1 have described was confined to the part. adjacent to the decorticated space ; but it has been long known to gardeners, that taking off a portion of bark round the branch of a fruit-tree occasions the preduction of much blos- som on every part of that branch in the succeeding season. The -blossom m this case probably owes its existence to 2 stagnation of the true sap extending to the extremities of the branch above the decorti¢ated space ; and it may therefore be expected that the alburnous matter of the trunk and branches of a resinous tree will be rendered more solid by a similar operation. I send you two specimens of the firewood I have aesrned! the one having been taken off above, and the other below, the decorticated space. The bark of the latter kind scarcely exceeded one-tenth of aline in thickness ; the cause of which I propose to endeavour toexplain in a Fate communication relative to the reproduction oF bark. * The roots of trees, though of much less diameter than their trunks and branches, probably contain much more alburnum and bark, because they are wholly without heart wood, and extend to a much greater length than the branches; and thence it may be suspected that whem fit-trees are felled, their. roots. contain at least as much resinous. matter, in a fluid moveable state, as their trunks and branches; though not so much as is contained, in a concrete state, in the heart wood of those. — ' INVISIBLE GIRL. 69 : Vil. The Invisible Lady ; being an ‘Explanation of the Manner in what _ the Experiment which was exhibited in London, by M. Charles and others, is performed. In a Letter from a Correspondent. A Musi . ie are __, The experi- MS the acoustic experiment of the Invisible Girl, which ment of the has excited so much attention and curiosity, does not appear oie to have been hitherto explained in any publication, I have peen publish- sent you the following drawing and description of the manner €4. in which it is performed. I must, however, in justice ob- serve, that the conduct of this experiment has been kept in the most profound secrecy by the exhibitors, and that my in- formation was obtained from the account given of it by Mr. It Decal ga Millington, in one of his philosophical lectures, last winter, yoneet aD in Chancery-lane; where I witnessed the experiment in its in his lectures, full effect ; and by a comparison of his account with -the ex- hibition which I have since visited, and find perfectly to agree ‘with: his description, { am fully convinced they are one and the same thing. If therefore you think the account ‘Isend you worthy of insertion in your valuable Journal, it is quite at your service, and it may perhaps afford information, and gratify the nd of some of your readers. I am, Sir, your’s, &c. . . PAT nd X. Fig. 1, plate 2, represents a perspective view of all the The apparatus gnae apparatus of the Invisible Girl as you enter the room. ee It consists of a mahogany frame, not very unlike a bed- pets connected ‘stead, having four upright posts aaaa, about five feet con pela high, at the corners, which are united by a cross rail near =~ the top, b b,and two or more cross rails near the bottom, to strengthen the frame: these are about four feet in length. The frame thus constructed stands upon the floor, and from each top of the four pillars aa a.a spring four strong bent ~ brass wires, converging at the top c, where they are secured by a crown and other ornaments. From these four wires a hollow copper ball, of a foot in diameter, is suspended by slight ribbons so as to cut off all possible communication with the frame. ‘This globe is supposed to contain the in- —and the sounds seem to proceed ~ from the trum- pets. But the sound is really con- veyed by a tube, “INVISIBLE GIRL. visible: being, as the voice apparently proceeds from the in- terior of it;: and for: this purpose it is equipped with the mouths of four trumpets, placed round ‘it’ in an horizontal direction, and at: right angles te*each other, as may be more distinctly seen at fig. 2, where g is the globe, ddd d the-trumpets, and-4 bd the frame surrounding: them, being about half an inch. from them. _When a question is’ pro- posed, it is asked from any side of the frame, and spoken into one of the trumpets, and an answer immediately pro- ceeds from all the trumpets; so loudias to be distinctly heard by an ear addressed to any of them, and yet'so distant and feeble, that it appears as if coming from a very diminutive being. In this the whole of the experiment consists, and the variations are, that the answer may he returned in several languages, a kiss will be returned, the breath, while speaking, may be felt, and songs are sung either accompanied by the piano forte, &c. After describing the manner in ohn this effect is hepugh about, it’ will immediately appear that. the whole deception consists in a very trifling addition to the old and well-known mechanism of the Speaking Bust, which consists of a tube from the mouth of a bust, leading to a confederate in an adjoining room, and another tube to the same place, ending in the ear of the figure. By the last of these, a sound whis- pered to the ear-of the bust is immediately. carried to the confederate, who instantly returns an answer by the other tube, ending in the mouth of the figure, who seems to utter it: and the Invisible Girl only differs in this one cir- cumstance, that an artificial echo is produced by means of the trumpets 5 and thus the sound no longer appears to pro- ceed in its original direction, but it is completely reversed, The apparatus necessary to produce this effect, is seen ‘In Description of fig. 3, where 5d represent two of ‘the legs of ihe frame, one of the tube and other appara- tus. which, as well as half the hand-rail, is Sade into a tube, the end of which opens in the rail immediately opposite the center of the trumpet. TPhis hole is very small, and con- cealed by reeds or other mouldings, and the other end com- munigates by a long tin half-inch Pipes p Ds concealed under the boards of the floor, /f, and passing, concealed, up ‘the wall of the room to a large deal case, £, almost similar to an inverted funnel, large: neheugh to contain the confederate, MOON IN’ PLANO. and:a»piano-forte.. Any question asked: into one of’ the trum- » pets, «will be immediately reflected back to the orifice of the tube,.and distinctly heard by a person in the funnel, and - the answer uttered by them, ora song or tane from the piano- forte will be distinctly heard at the mouths of the trumpets, >but nowhere else, and there it will seem to come precisely _ from, the interior of the globe. A> small hole closed’ with glass is left through the funnel and: side wall of the room, as at w;,by means of which the concealed person has an oppor- tunity of observing and commenting upon any cenarmnce shit er take ace in the room, MO RSy ‘ = - Vil. Mr. Witriam Russer, of Newman Street, has offered Pro- posals for publishing, by Subscription, two Engravinys of the ~ Moon tw Piano. By the late ears util neg Esq. R.A. ei ‘with the following adress. Tue late Mr, Russel, celebrated amongst . men of science ~ for the production of the Lunar Globe; left, at his. death, ~ two Lunar Planispheric Drawings, the result of numberless telescopic observations scrupulously measured by a micrometer: one of which Drawings exhibits the Lunar Disk in a state of direct opposition to the sun, when the eminences and depres- sions are undetermined, and every intricate part, arising from ‘colour, form, or inexplicable causes, is surprisingly developed __and exquisitely delineated ; and the other, of precisely the same proportion, represents the eminences and depressions of ~ ‘the moon deéermined as to their form with the utmost accuracy, BY producing their shadows when the sun is only a few degrees _ above the horizon of each part. The former of oe was “beautifully and most correctly engraved by Mr. Russell, who had likewise very considerably advanced in the engraving of the latter, when death terminated his labours: it is, however, ‘left in such a forward state, that it will be finished with the _greatest exactness, and all possible dispatch, ~ Mr. William Russell, son of the late Mr. Russell, proposes “to 0 publish, by subscription, these lunar plates, which have been ra! a MOON IN (PLANS, long, promised. to the scientific world : and the» first engraving is now offered-for their inspection., The whole will be incom- patably. the most complete lunar wark ever.offered in. any age —a work, the more. carefully it is: examined, -either as to -its accuracy or elegance (effected indeed, by extreme labour during twenty-one years), the:more it will excite the wonder: asi id miration of the diligenti inquirer. $0): tp)! a The utility of these engravings is best. candi nial mn the author’s own words: “ The principal.use of the moon to as= tronomers, is, that of ascertaining the longitude of places. by the transit ofthe earth’s shadow, when the moon iseclipsed. The shadow of the earth coming in contact with many known spots, if the observation be made in different “places at the same time, the longiaude of each place could by this means be ascertained with great precision, provided the spots to be made choice of be sallighenide represented and recognised 5 but there being wo faithful. delineation of the moon, and the edges of those spots which are known being undefi- ned, the observations made have’ not been so useful as could be wished: for this purpose, it is believed, Mr. Russell’s labours will be found very useful, and. will very much add to the certainty and precision of the observations on Lunar elipses; as the chief design of his planisphere, representing the moon in a state of opposition to the sun, is directed to this end, and which he has spared no pains in bringing to perlection.” These engravings, it is expected, will not only prove of great utility to the astronomer, but lead to very important specula- tions in natural philosophy. The remarkable changes of forms in vatious eminences, the different radiations of light observable at one ageof the moon and not at another, with its numerous surprising phenomena, are in these plates faithfully and fully expressed, soas to forra.a work, it is presumed, highly inte- resting in the departments either of Astronomy or Natural Philosophy. es CONDITIONS. 1. The diameter ofeach Planisphere is fifieen inches. —2.The impressions shall be delivered in the order of subscribing. —3. The price to subse ribers for the work is five guineas : an ad- vance will be mage to non-subscribers, when the whole has been completed,.—4 One half of the above sum to be paid LIGHT AND HEAT COMPANY, 73 at the time of subscribing ; when one part of the work will _ also be-delivered.—5. The description, &zc. of both plates will be given when the second plate is paid for and delivered.—§. The-whole of the printing shall be executed by the first prinieae the best wove paper, ~ Subscriptions arealso received at Mr. Fapen’ s, Scabpapher to his Majesty, and to His Royal Highness the Prince of Wales, Charing Cross. . Sir Josern Banxs, K. B. Sir H. ENGLEFIELD, Diz. Masi nies? MILNER, HerscuHeEn, Hon. H. Cavene ' prsa, Earl! of E¢rrmont, are amongst the names already a aio VIil. Letter oy tei Srom a Correspondent, whether the Light and Heat Company ?s entitled to public Encouragement. To Mr. NICHOLSON. ~~ SIR, og SEND yen, a collection of papers which have beeri cir- Letter of in- culated. by Mr. Winsor, -patentee for lighting apartments by ing Me Wie the gas from pit-coal, who is soliciting an immense subscrip- sor’s Light and tion, in order to-establish a public company. On former oc- Heat Company. casions, I observe that you have not hesitated to give your Opinion without reserve, upon subjects by which the public might be benefited. I trust you will suffer the same motives to operate on the Se Dia occasion. Lam, Sir, Your obliged and constant reader, M. P. “REPLY. Ww. N. ra; sO Uicervicth Thad Pr of the wll aike in nrfNestion some time ~agoyIvdid not find sufficient motives for spaying any: pavti- 74 LIGHT? AND “HEAT OOMPANY, cular atténtion to it, until the spapers' were sent me by my correspéndent, and they now comeso late, that I can treat the subject only in a cursory'manner. The following remarks Will require no apology to my readers for the freedom with which they are made. a re iy reer | I. "Fo give light by the gas*from coal was. many years ago known, long done’ by Lord Dundonald. « it was afterwards shewn in public, Sein nig 2m? 1784, by Diller and others. Mr. Murdoch (see Philos, patent: Journal, XI. 74. for May’ 1805) extensively applied this practice in Cornwall in 1792, and afterwards at Schon 1798, and since. And’many years afterwards, Mr. Winsor takes out a patent for this very object. He is not the first inventor as’ to the public use and exercise thereof, and therefore his patent is void by the statute of James I. | - pag mire II. Mr. Winsor, in his paper intitled. Terms and Conditions, 8 anew in- 6'¢. says his patent is vested in four respectable gentlemen, vention, he whose names, for the respectability of his project, he ought renders it void, ; ; . by sharing it to '0 have given as well as his own, He proposes, that, instead more than five. of the co-palentees engrossing the whole of their patent privi- leges to themselves, they will share them with\a large and respect- able number of their countrymen. Now as the Letters. Patent are merely grants of privileges, it cannot be questioned but that every one who shall be admitted to any share or interest in the privileges so granted, will become a joint patentee ; and of course, that if that number exceed five, the patent itself scriber, the patent itself, even if not otherwise exceptionable, becomes a nullity. 3 ae ; There i¢ no Ill. Mr. Winsor solicits subscriptions, on the condition that Sige A a company shall be established by an act of the legislature, an Set Oe a if the legislature were at his command, or as ifan act of i parliament could be had as a thing of course. I do not think it needful to discuss his calculations of profits, and the statistic inferences he pretends to draw from them. Much as they are open to objection, I would only ask, whether the legislature is likely to consent that he and his subscribers shall levy Gpon the nation an ‘annual interest of 5751. for every 5l, subserip- LIGHT AND HEAT COMPANY. "5 tion, to the amount of many millions—even supposing his merits as an inventor to be as much above par as my first paragraph appears to place them below it nee _IV. Lastly, as a matter of prudence between man and man, Neither the partners nor I would ask who are the responsible trustees for the subscrip- trusiees of tions, which, at five pounds each, would amount to one hun- Mr. Winsorare known. dred thousand pounds? I am very far from inviting a discus- sion of any man’s private character unnecessarily, and of Mr. Winsor I know absolutely nothing: but I must say, that in a —but they concern of much less apparent magnitude than the present, e Siew common sense and common integrity ought to have dictated — the insertion of the names of trustees in the printed papers before me. Two respectable banking-houses are indeed named for receiving subscriptions, and 1 should hope, for jy, ;. hoped that their credit as honourable men, that they have consented to the bankers be bankers to persons who are known and recommended to Who Know the | roject, do them as fair and proper connections, more especially in a also know the project of such apparent moment and doubtful import. [ tustecs. dare not presume the contrary; and all that I have to say on this head is, that it would have been. no more than simple justice and open dealing, if they had insisted that the public should also have known where the powers may be placed of drawing for the monies in their hands, and disposing of the whole at the pleasure or discretion of such drawer. Observations of Dr. nes taal BR ie, vile Water’ is not de~ Wate Pee of its Peg y Pe. ay ; $3. . i / Mess, ‘Humboldt ‘and Gay-Lusee, in an interesting memoir presented to the National Institute, and. entitled, “ Experiments on Ludiometric Methods, and the proportion of the constitutuent _prineiples ‘of the atmosphere, &c.,” are, as it appears, . of opinion, ‘that ‘ebullition is the most: effectual means of depriving water “of oxygen, . In effect, they: have availed themselves. of this. operation only for obtaining this 76 _ OXIGEN aoe WATER. end; and they afterwards assert, that where water is gradu- ally heated, the proportion of oxygen encreases as the: heat approaches toebullition; whence they have concluded, that in the degree of the heat constituting the temperature of ebul- lition, the oxygen is most easily driven off, and that there is no other power for disengaging it. But we find, by experi- ence, that ebullition is not sufficient to divest the water of all the oxygen it contains, whether attached or combined. Ebullition deprives water of much of the oxygen and other gas with which it is impregnated, but it cannot entirely separate them ; for it is proved that water well boiled always retains oxygen, Nothing but congelation, and the respira- tion of fishes, can clear water entircly of its oxygen: these two are the only means that complete the separation from water of all oxygen it contains interposed between its glo- bules; for it is not till then that we obtain an exact proof of its being divested of it. As to the rest, the detaching and decomposing power of heat, at the degree of ebulliticn, is not sufficient to overcome the affinity and attractive power of all the oxygen united with the water ; a part of it ‘remains obstinately fixed, in spite of all the heat. .. Fishes, as I have elsewhere observed, are the eudiometers of water, and one of those, shut up in a body of water, is capable of separating, by means of its respiration, in several hours, all the oxygen from the water, and to exhaust it en- tirely of this principle. It is by this method that boiled water is proved to be not entirely divested of oxygen, but still con- tains it, If we take a quantity of water, and boil it for any length of time, and then pour it quite boiling into a bottle, or a glass vessel with a narrow neck, so that it be full up to the top; if a portion of oil be poured upon it to prevent the air from penetrating, and it be then suffered to cool: in this state, let the vil be removed, and a little fish thrown in, and the oil be immediately replaced, the fish will continue to’ live some time in this water, and will be seen to breathe. Lik Ebullition, therefore, has not removed all, the oxygen of the water; but.a portion of it remains sufficient to serve for the respiration of the fish; for when the water is really deprived of all its oxygen, fishes thrown into it die instantly, OXIGEN IN WATER. Because they cannot breathe. This is -@ matter’ of fact! = any one can verify. bi isakti wll But again, let us take Lae and infroduce it by Tittle: avd little into a glass bottle, continuing to do so in proportion as it melts and lessens in bulk, till, being entirély melted, it shall fill the bottle with water up’ to the brim; let oil be ims mediately poured on the surface, so that it shall rise some inches in the neck of the bottle; let ‘us then permit it to _acquire the temperature of the atmosphere, which 1 suppose to be warm, and capable of melting the snow ; if, in’ this case, by some expedient, the oil placed on the snow water, and which embarrasses the neck of the bottle, be drawn ‘off, and we introduce, with the greatest possible quickness,’ a fish, as vigorous as possible, and cover the water immediately over with oil, we shall see with what pain this ‘animal is“Affécted in Pig water; he is attacked with a mortal convilbion, ai ina little time ceases to live. rp i see Such water as is obtained ‘from’ melted shove, “is “equally _ obtained from ice or from hail, by introducing pounded ice or hail, by little and little, into a bottle,’ with the attentioris here mentioned; and by throwing ih ‘a fish, afier these mat- ters are melted, the animal dies’ in “this as in i bikie water," viopelegd nae po Meigs Thus we clearly see that ‘congelation expels tal water all. ths oxygen it contains, and on that account fishes “cat- not | live, because they cannot breathe i in ite mmm ah of snow, : 7s under whatevér’ form it _may be, is a mortal Lirias for” the inhabitants of that fluid, because they find it Vout “of ‘oxygen gas, . which stops ‘their respiration, "These Waters ae’ ek- hausted of oxygen, | like that which’ has sé cived' ae ie Pia tion of one of these animals. until its death." Ifa bottle be ‘filled. with any, kind ‘of walter, ‘that’ i8 to 8) fs say, of river,, ‘of, ‘well, -or of spring water,” ae ‘a Tittle’ fish be put into it 5, and_ aflerwards to hinder ‘thet! Water frém the absorbing oxygen of the atmosphere, if dibs poured into theneck of the bottle upon the watet, the fish will live'many” hours ;, but after, he shall, by rege Jive exhatisted all onal foarrs it he will die as soon as ahe4 isin this’ water. ° But if it be wished that the water should again become fit for 77 OXIGEN IN WATFR. maintaining the life of fishes, this may be instantly effected by pouring it into a large vessel, where it can again absorb the oxygen of the eae he same observation is true with regard to the snow water; we may render it capable of supporting the lives of fishes, and of serving for their respiration, if we put it in a vessel that shall expose a large ‘surface to the air, in order that it may again absorb the oxygen it has thrown off during the congelation. Snow or ice water is then, without any doubt, destitute. of oxigen, as well as that which has served for the respira- tion of fishes, who have the faculty, by this process, of “Sepa rating and of absorbing all the oxygen, which is there ina state of solution. There is not the slightest difference oo ee snow and. ice water; with regard to the privation of their oxygen; both are divested of it. So that what those two respectable physicians have advanced in their memoir, does not appear to be well founded. It appears, according to them, that ice contains a portion of oxygen, but that water in congealing throws off a great part of it, mixed with azotic gas, and that water in its transformation into snow throws off less air than when transformed into ice; because, when they caused snow newly fallen to melt, by gradual warmth, they have obtained from it a mass of air almost double that afforded by melted ice. It is true we see much air disengage itself from snow while melting : but it is not any air contained in the frozen or chrystalized water which constitutes the snow ; but it is an air confined between the interstices of the snow, remaining attached to the faces or surfaces of the chrystals that com- pose it; and itis for this reason that we see much air pro- ceed from the snow while meiting. I have already stated, many of those observations in two memoirs on snow water, inserted in the Journal de Physique of Paris, of Ventose, in the year 7, and of Thermidor, in the year 9; for which reason I shall not extend these reflections to any greater length. SCIENTIFIC NEWS. — r) C& DiIIh he ; oe tad : Ona Nig) B99 SCIENTIFIC NEWS. «Royal Society. fei Bakerian Lecture has been lately read before. the Chemical Royal Society by H. Davy, Esq. F.R.S., on Electricity con- spencyof elec- Ticilye sidered as to its chemical agencies. Mr. Davy has found that a great number of bodies are capable of being ‘decomposed by electricity ; particularly those, containing alkalies, acids, » alkaline earths, and metallic oxides: and he finds that their elements are separated in a voltaic circuit, made with water, ihe voltaié in such a way, “ that all acid matter arranges itself round the current s¢pa- : rates acids from positively electrified metallic point, and all alkaline matter, Weir Wasess am and the oxides, round the negatively electrified point. in that the a this way, he decomposes insoluble as well as soluble com- eae aems- pounds. Sulphuric acid and the earths are separately pro- the positive cured from the earthy neutral compounds, and soda and pot- iat heute ash evolved from minerals and stones containing them, the negative. By the attracting and repellent powers of the different This power is electricities, acid and alkaline matter are transported through ¢? Sin"® ieee it will prevent menstrua for which they have a strong attraction, and through the usual ef- animal and vegetable substances, Thus sulphuric acid will fects of chemi- 7 ; 3 I cal affinity. be repelled through an alkaline solution from the negative to positive point, and vice versa; potash or lime will be repelled from the positive point to the negative, through an acid solution. Mr. Davy explains these phenomena by means of some other Mr. D.’s ex- experiments. As in ‘ Voltas contacts of metals, copper oe sa and zine appear in opposite states; so Mr, Davy finds that that he finds acids and alkalies, with regard to each other, and the metals, oe aoe me possess naturally the power of affording electricities,” and possess respec- may be said to be respectively in states of negative and po- UVély the ne- aie c : : __ Sative and po- sitive electrical energies; and the hodies naturally negative sitive states, are repelled by negative electricity, and the bodies naturally 24 Shea quen ar positive attracted by negatively-electrified points, -— ae by the contrary states, 80 Question : whether che- mical affinity and clectric energy be not the same power? These general principles ex-— plain many galvanic and chemical facts, and afford new methods of analysis. SCIENTIFIC, NEWS. As chemical affinity is modified, destroyed, “or increased, by modifying, destroying, or increasing the natural electrical states of bodies, and as all bodies that combine chemically, which have been accurately examined as to their electricities, are in states of opposite energy, Mr. Davy puts the question, “Whether chemical unions and decompositions are not the result of the electrical energies of the bodies? and whether elective affinity is not the same property with electrical ener- gy?” He enters into various illustrations and applications of this theory, which naturally arises from the facts... | The ‘general principles explain | a number of phenomena before obscure : why acid and alkali were obtained from water apparently pure; the acid and alkaline bases produced by the different poles of the pile ; the decomposition of muriate ‘of soda between the plates; the separation of water into oxygen and hydrogen, by attracting and repellent powers acting equally upon other bodies. The experiments offer new methods of analysis, and. will apply to the solution of many natural phznomena, , 5 0 I et en > ee rar ae me ea Printed by Paolo Da Ponte, 15, Poland-Street, Oxford-Streete Wicholsons Phitos Journal Vol. XVLPLIP. 40. Scale for the vanishing Lines of Perspective | by Geo Camberland E£7q. Theory of mixed Cases Toa 3. ! sy by John Gaaghki9. ames Nathrd “ thei’ aa itholsons Lhiles.Journal VolLAVL pl.2 /p, 80. Hi | i" q WA } ra i i mei) it ll i | [| a ; The invurtble Lady. Nichwisons Lhiles Journal Vol AVL plz p. 60. a | a Se - JOURNAL NATURAL. PHILOSOPHY, CHEMISTRY, AND THE ARTS. ere See FEBRUARY, 1807. rs ARTICLE I. Account of a Fact, not hitherto observed, that the Galvanic Power heats Water while.decomposing it in Part. Ina Letier from Mr. Joun Tarum, Jun. To Mr. Nicnoxson. Sir, In the various galvanic communications which I have Circumstance had the pleasure of consulting in your invaluable Journal, as meaaapeie | well as in lectures and volumes on that interesting ‘sub- ied, ject, to which I have attended, I do not recollect any men- composition of tion being made on a circumstance attending the decompo. ¥"""' sition of water, which I observed about two months ago, in preparing for a public lecture 1 was about to deliver, which, if you think worthy a place in your Journal, is very much at your service. In the experiment alluded to I made use of four troughs Experiment. : : 3 , Water was de- of the following dimensions, viz. two of 26 plates, each composed by plate 50 inches, and two troughs of 25 plates, each plate 36 teorehs ck con= Ae Vou. XVI.—Fers. 1807. a4 G siderable sums inches, face. P 82 GALVANISM. inches, of course I had the power of 4400 inches. The oxidating fluid I made use of was good nitrous acid, with aboué sixteen times its bulk of water. On passing the gal- vanic fluid through about one ounce of water, by means of platina wires, I was much surprised at the quantity of calo- Much heatwas ric which was liberated as the water became decomposed 5 producedin the temperature of the tube which contained the water the water. ; seemed to be about (as near as I could judge by the touch ) 180° of Fahrenheit; but as I wished to ascertain the tem- perature more correctly, I immediately applied the bulb of a thermometer, though it was very unfavourable to ascer- tain the temperature, as the bulb of a small thermometer could touch a tube of one inch diameter at a very small sur- Thethermo- face, but the mercury soon rose 10°, Not having any person meter shewed with me, and endeavouring to regulate the wire which com- xo deg: municated from the battery to the tube of water with one hand, while the other was engaged in holding the thermo- meter against the tube. I accidentally brought the positive and negative platina wires in contact, which exploded the gases, and forced the tube violently up a considerable height, which falling on the table, broke, and prevented me accom- plishing my wish relative to the temperature of the water under decomposition. Another expe- A short time after, in my lecture on the subject, I noticed riment. the circumstance ; and one or two of my audience, after the lecture, on applying their hands to the tube while the water was decomposing, hastily withdrew them on account of the heat. ; Icannot, Sir, account for the liberated caloric by, any How was the : . : ‘ heat produced? Other means than supposing that the galvanic fiuid furnished more caloric than was necessary to convert the water into gases. If, Sir, this meet with an insertion, I shall commu- nicate more on the above subject the first opportunity ; until when permit me to remain, Your’s, most respectfully, Dorset Street, JOHN TATUM, Jun, Jan. 5th, 1807. i LIGHT “FROM COALs 83 Ti. & ; Account of the Discovery of the Means of illuminating by the Gas from Coal, by Dr. Cuayton, previous to the Year 1664. Ina Letter from Mr. Joun Weester. To Mr. Nicnotson, Sir, I READ with great pleasure your just observations on ie ae Mr. Winsor’s gaseous proposals for enlightening the inha- ago discovered bitants of this metropolis. The purport of these few lines is merely to say, that the discovery of the carbonated hy- drogen gas took place previous to the year 1664. Happening a short time ago to be reading some of Boyle’s manuscripts, in the British Muscum, I met with a paper of the following title (Ascough’s Manu. 4437). ‘¢ Experiments concerning the Spirit of Coals, in a letter ra Dr. Clay- to the Hon. Mr. Boyle, by the late Rev. Jas. Clayton, D-D. * B. Mus.” As I did not copy the whole of the paper, I have taken the liberty of sending you the few short notes 1 made at that time. The experiments were undertaken by Dr. Clayton,in Con- pyistory of the sequence of having discovered that gas, issuing from fissures discovery. near a coal-pit at Wigan, in Lancashire, ignited when a burning candle was presented to it. Dr. Clayton on observing this effect distilled coal. He ee first observed that ‘¢ Fleghm” came over, afterwards aC¥}\cceived’ *¢ black oyle,” and then an ‘* inflamable spirit.” He col- the gasin a lected the last product into bladders, and amused his friends bladder. by pricking a hole in a full bladder and igniting the gas. If you think it worth while to insert this in your valuable Journal, it may be the means of gratifying some of your readers by referring them to the original paper, the number of which I have already put down. “From your obliged humble servant, Jan. 5, 1807. JOHN WEBSTER. G2 84 The polisher must be of pitch, rather soft, The larger the polisher the flatter the figure. REFLECTING TELESOOPE, Til. Observations on the Metallic Composition of the Specula of reflecting Telescopes, and the manner of casting them ; also a method of communicating to them any particular. Conoidal Figure; with an attempt to explain, on scientific Principles, the Grounds of each Process, and occasional Remarks on the Construction of Telescopes. By the Rev. James Litrin*, [Concluded from p. 59.] Tar consistence of the pitch is, in this business, an article of the first importance. Soft pitch will give to the polish a higher lustre, and will less expose the face of the mirror to scratches: but, if it be too soft, the mirror will sink in it, like a, seal in soft wax; and the figure of the polisher cannot be preserved, nor the furrows in it from being defaced. It must, therefore, be always harder than common pitch is, in a mean temperature of the air in this climate. And, after the polishing powder is bedded in it (which must at first be laid on so copiously, that the pitch may not rise up to the surface, between the particles of it, ) and when the mirror has been worked on it a little time, then all the loose particles of the powder ought to be washed off, from the edges and furrows of the pitch, with a sponge, or brush, (made of fine hair,) under water, that no grains may get on the surface, and injure the polish. And, if this be attended to, and the pitch be a little softened by heat, when the powder is first applied, it may be used of a con- sistence hard enough, without inconvenience: but, if it be made so hard, as not to sink at all, or expand itself, under the mirror, I believe it will never communicate to it a perfect figure. From what has been here laid down, it must be obvious, that, by diminishing the size of the polisher, whether it be ofa ‘Srewiae or elliptic'shape, the curvature of the mirror: will be brought nearer to that of a circle; and, by enlarging the polisher, the curvature will approach to that of an hy- * Irish Trangactions, Vol. X, perbola, REFLECTING TELESCOPE. 85 perbola, when the precautions here given are observed. Both these may be done, by spreading the 0% on the polish- er, toa greater or lesser extent. In the Gregorian telescope, the excess of curvature, iN The defects of the great mirror, may be remedied, by a defect of it’ in the mi large see . * . A : culum may e€ little mirror, and vice versd. It must be desirable, to a a compensated fabricator of this instrument, to understand why this is so; by the figure of and how achange in the curvature may be effected: for an the smaller. artist cannot well execute a project, the design of whichis to him unknown; nor improve by trials, even repeated, if they are made in the dark. I apprehend, that, in this kind of telescope, the mirrors are commonly selected, out ofa number finished of each size, as they happen to suit each other: and, if there should be but few pairs in the assort- ment, se hice ievesnaviabe compensate one another, few good telescopes will be produced. ‘This would be less frequently the case, and the Gregorian telescope be more improved, if a more certain method were known, of giving, to each pair, their appropriate figure at first, or of altering it in either, where it is defective. Perhaps persons, not much versed in optics or geometry, may be assisted, in discovering the evil, and the remedy, from the following remarks; which are given in words, in order to dispense with a diagram. The curvature of the circumference of a circle is uniform Popular obser« im every part, being (in anarch of it, of a given length) so Vai Te: daisy much the greater, as the radius is smaller, and vice versa. But the curvature of the ellipse, parabola, and hyperbola, is not uniform, but continually diminishes, from the vertex of these curves, (which answers, in the present case, to the center of the mirror,) to the extremity on each side; but it diminishes less in the ellipsis than the parabola; and in this than inthe hyperbola. So that, if we suppose a bow to be bent, at first, intoan arch ofacircle, and, when gradually relaxed, to become, towards its extremities, more and more straitened, as it unbends, while the curvature, at the very middle, remains the same, it will successively form. these three curves, in the above order. And, if concave mirrors had the same curvature with them, they would have the following properties. If the speculum be of a parabolic form, rays of light, The parabolic falling on it, parallel to its axis, or issuing from a luminous speculum is point good for the 86 Newtonian or Gregorian tele- scope. REFLECTING TELESCOPE, point in the same, so very distant, that they may be regarded as parallel, will converge, by reflection, to one point in the axis; which point is the focus. ‘The same is nearly true of rays coming from luminous points not far from the axis, or lying ina very contracted field of view, so as to make buta very small angle with the axis: the rays, coming from each single distinct point in the object, are converged to so many single distinct points in the image, formed at the focus of the mirror. Hence, the excellence of a parabolic mirror, for the larger speculum of the Newtonian or Gregorian tele- scope*, lf * But, because a parabolic mirror reflects, to one point, rays, that fall on it, parallel to its axis, it follows, that it will not converge, toa point, rays, that are diverging or inclined to its axis. The former, (if the point, from whence they radiate, be in the axis of the mirror,) would be reflected from any line, drawn diametrically across the mir- ror, in a caustic curve double and cuspidated: the latter, (being in the same plane in which is the radiant point, infinitely distant, and the axis,) would form acurve nodated. So that the excellence of a para- bolic mirror is for viewing remote, but not near objects. And a per- son might thus be deceived, who would judge of the goodness of a telescope, only from its rendering print legible, at a small distance, from whence the breadth of the great mirror would subtend an angle of sensible magnitude: for the pencils of rays that issue, diverging from each point of the printed letters, will be reflected, by the central part of the mirror, to a focus nearest to it; and the rays of each pencil, that fall on the exterior annuli of the mirror, will be reflected to points more remote from it. So that if, in the Newtonian and Gregorian telescope, the great mirror were of the correct figure of a parabola, and the little mirror, of the latter, were that of an ellipsis; and, if either telescope were adjusted to distinct vision, when the innermost zone only of the great speculum is exposed to the light; yet, the oh- ject would be indistinct, if seen by the rays reflected from the outer zone, unless the little mirror were removed farther from the great one. Hence, aspherical mirror is better than a parabolic one, for viewing very near objects; and neither of them can be equally adapted for viewing these and very remote objects. The distinctness of the tele- scope is, therefore, best proved, by directing it to the stars: if it shews, clearly, the fasciz,on the disk of the planet Jupiter, or the ring of Saturn, it will deserve to be approved of, I have ground and polished, in the manner here described, the mirrors of a little Gregorian tele- scope, of nine inches focus, which shewed these objects most distinetly} and I could not afterward, with much greater pains, execute another one, (neither indeed did I ever see one,) of that size, of equal accuracy; which served to convince me, of the exquisite correctness required in the . — REFLECTING TELESCOPE. 5 87 ‘ If the mirror be of an elliptic, or oval, curvature, rays, ‘The small spe- issuing from single points, in, or extremely near to one of Tae to 3 P F e elliptical. its foci, and falling on it, (such as the rays proceeding from the single points in the image, formed by the parabolic larger syeculum,) will be converged to so, many single distinct points, in the other focus of the elliptic mirror. Hence, the excellence of an elliptic figure, for the smaller speculum of the Gregorian telescope *, But the case is very different, the figure of the mirrors, and of how great perfection the instrument is susceptibie. Telescopes have been recommended, for their enabling persons to read gilded letters, at a considerable distance; but this is an improper method for determining their merits; for (beside the ground of error now mentioned) a much greater quantity of light is reflected from gilt letters, than from those of eommon print on paper. * But this will not be the case, if the rays diverge from points, remote from the axis of the speculum, as to make a con with it, and to fall very obliquely on the speculum : which would be fying power of the case, if the field of the telescope were too large, or if the focus of the Gregorian the great speculum were too long, with respect to that of the lesser Te one: because, in either case, the image, formed by the great mirror, chip demean: which is the object, with regard to the lesser, will have too great lati- ent on the eye- tude; and the extreme pencils, diverging from it, fall, with too much piece. obliquity, on the latter, to be collected by it, to single points, in the second image. And, on this account, there is, in the Gregorian tele- Scope, a limit set to the degree of magnifying, so far as this depends on the mirrors, be their figure ever so correct. And, if any aberration prevail, in the image formed by the larger concave, they will be mag- nified by the lesser, were it perfect, in the proportion of the focus of the former tothat ofthelatter. Iam of opinion, that it is better not to aim at a high degree of magnifying, by the little mirror of this tcle« scope; but, to endeavour to secure the correctness of the second image; and tolay the chief stress of the amplification (as it is in the Newtonian telescope) on the eye glasses ; because of the above circum~ stance, which no-correctness, nor compensation of the mirrors, can remedy. From this inconvenience, here stated, the Newtonian tele- scope (the most perfect of all the constructions, that ever were or ever will be devised) is entirely free. This the author effected, by putting the eye-glasses on a different axis from that of the mirrors; by which he was enabled to make the lesser mirror a plane surface. And it will appear, on due consideration, that he was obliged to introduce this change, in Gregory’s telescope, of necessity; and not from a low am- bition, to which his mind was superior, that of obtruding his own inventions, to supplant those of equal merit by other men: though he has not stated all the imperfections of the Gregorian form, nor the advantages of his own; having only, in answer to objections, and, as it were, reluctantly, mentioned the chief circumstances, justifying the 5° It is adviseable siderable angle that the magni- alteration he had recommended. in 88 REFLECTING TELESCOPE. in a spherical or hyperbolic mirror, From either of these, the rays, which issuein acone or pencil, from single, lumi- nous, distinct points, in a very remote object, and fall on them, will not converge again, toso many single points; bat will, in the mean focus ,of the mirror, be dispersed, and blended together in a smaJl degree, yet sufficient to produce an universal haziness and indistinctness, ovee the whole sur- face of the object viewed in a telescope, having its large mirror of these forms, because it occurs, with respect to every point in such object; of which the following are the circumstances. Effects of sphe-- If the‘mirror be spherical, those rays, nearly parallel of vical mirrors. PF ; F ; 2 each pencil, which fall on it, next to its centre, will con, Contrary aber- ration of the hyperbolic murror. verge toa point more distant from the mirror, than the focus of any rays, that fall between the centre and outer édge of the mirror. And those, that fall on the outer extre- mity of it, will converge to a different point, nearest to the mirror: and the rays, which are incident on the several con- centrical annuli, indefinitely narrow, of which the face of the mirror is composed, will have an indefinite number of points of convergence; each annulus its own point, and all lying in a series, in the axis of the pencil, between the points, or foci, of theextreme, and of the innermost. annu- lus *. So that no entire incident pencil will, after reflec- tion, converge to one point, unless the radiant point were ‘in the centre of curvature of the mirror. The property of an hyperbolic mirror is of the same na- ‘ture, but with effects reversed: for, in this, the rays parallel ‘to its axis, which are incident on its outer annulus, will converge to a point the most distant from it; andthe rays, falling on its’ innermost annulus, will have their focus the nearest to'it. Andthis is easy to comprehend: for, as the curvature of the hyperbola continually diminishes from its vertex, on each side, a parallel, or diverging pencil, falling * This property of a spherical mirror has never, so far as ' know, been synthetically demonstrated, by any optic writer, thou, it isa fundamental theorem in catoptrics. Mr. Robins derisively obj. ed to Dr. Smith, that he had not demonstrated it. The Doctor, I believe, might have retorted the same charge on Mr. Robins. I have some reason to think, it is difficult to give such a demonstration of it, and that it will reflect credit on the person who furnishes it. at REFLECTING TELESCOPE, ata distance from the vertex, on a mirror of this form, must (as in the case of a mirror of greater radius, i. e. of less cur- vature) have its focus formed farther from it, than if it were incident near the middle or vertex, where the curvae ture < ? the mirror is that of a circle of lesser radius. 89 And thus it ighrvsion’ that, as the seyeral pencils, re- These errors flected by the g#at mirror, when it is spherical or hyper- 47¢ Pot cor~ | ki ; : ted by the bolical, do not converge, each to a single point, but to a kal ieee series of points, whose length is the depth of the focus of the lum. mirror; so, neither do these pencils, in proceeding on to the little mirror, diverge each from a single point, but from the same series of points. So that, though the little mirror ‘were formed truly elliptical, it would not make each of these pencils converge again (at the place of the second image, formed behind the first eye-glass) to single points, but to another series of points; by which the rays of con- tiguous pencils would be blended with one another, and make the object which is viewed, by means of these pencils, so transmitted to the eye, and, by it, refracted to a third series of points, near the retina, at the bottom of the eye, appear hazy and indistinct. \ These remarks will be applied to our present purpose, by Inductions. considering : > First. That the rays, reflected by the several annuli, in the surface of the great mirror, will fall on the annuli of the same order, in the little mirror; the rays from the outer, inner, or intermediate annuli of the one, proceeding to the like annuli in the other. Secondly. ‘That the farther the focus, or point of con- vergence, of any annulus of the great mirror, is distant from that mirror, the nearer will be the point of divergence of this part of the whole pencil, (among the series of such points), to the little mirror. Also, that the interval, be. tween any one point in the series and this mirror, cannot be altered, by moving the mirror, without, altering the intervals of allthe rest; which, after the telescope is brought to the distinctest vision, cannot be permitted. Thirdly. ‘That, if the focus of any annulus, of the gfeat Rationale af mirror, be farther from it, than those of the other annuli, the figure of and, consequently, nearer to the little mirror than those ; ‘R¢ small mir the rays, issuing from it, to this mirror, will not be reflected Vou. XVI.—Fes. 1807, H by ror, 90 Instructions for examining the adaptation of the mirrors to each other, / RETLECTING TELESCOPE. by it, to the same point with those of the other annuli, un- less the curvature of the corresponding annulus, of the little ’ mirror, be increased, in the proportion of its radius to that ofthe great mirror; for, then only will the focus of rays, reflected by this annulus of the little mirror, be shortencd, as much as, by the effect of that of the same annulus, of the great mirror, it would otherwise be lengthened. The same > is true, vice versa, if the focus of any annulus, of the great mirror, be shorter than those of the other annuli. Fourthly. That, if there be any excess or defect, in the curvature of the great mirror, from that of a parabola, (and, consequently, a contraction, or elongation, of the foci, of the extreme rays of the reflected pencils, ) there is no remedy, while this remains, but to make the little mirror so much deficient, or excessive in curvature, from that of an ellipse, (and, benbugecublis to lengthen or contract the foci of the extreme rays of the pencils reflected by it,) as its focus is, in proportion to the focus of the great mirror; there being no other means of reducing all the rays, of each pencil, to one point, at the second or conjugate focus of the little mirror; by which alone, the second image, consisting of such points, can be formed, and viewed distinctly, beget the last eye-glass. From all which, it is manifest, that, if the curvature of the great mirror be hyperbolical or deficient, then that of the little mirror ought te be spherical or excessive; and if the great mirror be spherical, the other must be parabolical or hyperbolical, according as its focus is long or short, in respect of that of the great mirror. Should the telescope be faulty, from indfstinctness of vision, it may be corrected, by altering the figure of either of the mirrors, as shall be most practicable. And, to know what the alteration should be, the method, directed by Mr. Mudge, may be followed, of excluding the light from the central, middle, or extreme zone of the great mirror, by fixing, on the mouth of the tube, three annular diaphragms of pasteboard, &c. answering, in size and shape, to these_ zones respectively; by removing any of which diaphragms, the light will be admitted to the corresponding part of the mirror. If, then, by help of the adjusting screw, the ob- ject be first viewed distinctly, when the inner or central zone, 7 REFLECTING TELESCOPE. zone, only, of the mirror is uncovered to the light; and it be necessary, afterward, when it is seen by means of the exterior zone only, to remove the little mirror farther from the great one, (by turning back the adjusting screw,) in order to distinct vision; then one, or both of the mirrors, is deficient in curvature, i.e. the great one is hyperbolical, or the small ene parabolical. And, on the contrary, if it be necessary, in this process, to bring the little mirror nearer to the great one; then one or both of the mirrors is spheri- cal. For, in the former case, it is plain, that the mean focus of the outer zone of the little mirror is nearer to the second eye-glass, than that of the inner zone; since it is necessary to withdraw that focus, by putting back the little mirror: and the contrary is evident, in the latter case. ‘The former could happen, only by the focus of the extreme rays, of each single pencil, being too far from the great specu- lum, (i. e. frem its being hyperbolical,) and too near to the little one; or from the latter being deficient in- curvature, near its edges; and thus throwing the focus of ‘the rays, that fall there, too far from it, and too near to the last eye- glass. The second effect could arise only from a figure of the mirrors, the reverse of this. In the Newtonian tele- scope, there can be no doubt, where the defect of curvature is, because it has but one concave mirror. When it has been thus determined what the defect is, means must be employed to correct it; and it may be ex- pected, that, unless some certain snitsele of effecting a dif. ferent curvature of the great mirror, from that of the little one, is discovered, and skilfully practised, there will be but few good telescopes, of the Gregorian form, constructed. For, if both mirrors be polished, in the same manner and method, it islikely, that the defects in their figure, and the species of their curvature, will be the same in both. Where. as, it has been shewn, that all these ought to be directly contrary in one, from what they are in the other ; referring to the parabola and ellipse, as the standard degrees of cur- vature. gees Now, the circumstances, which, in the method of polish- ing above-mentioned, havea tendency to produce particular Species of conoids, fate been already explained, and need‘ ‘not be repeated. But, as to the means of altering. any figure H 2 already 91 How to correet the curvatures —by means of* the polisher, without grind ing anew. REFLECTING TELESCOPE: already given, to the -great mirror, in the Newtonian tele- Scope, or to either of the mirrors in the Gregorian, which hap- pens to be unsuitable to the other one; I have to observe, that, in my trials, I have found this could be effected on the polisher, without putting the metal to be ground again upon the hones. Forif it has, at first, becn formed to a toler- ably correct figure, of any species, then a very small re- duction, of the substance of the metal, will produce a suffi- cient alteration of itsform. If the change required consists in a diminution of curvature, a continuation of the process, under the regulation before-mentioned, will, without any alteration of the polisher, generally, be sufficient to pro- duce it, from the degree of curvature of a circle, to that of the ellipse, parabola, or hyperbola, in order; or from any of these, to the others, in succession*. But, if the degree of curvature, already given, is to be increased, and to verge more toward the circle, as the limit, (beyond which no con- trivance could carry it,) then the polisher must undergo an- alteration. Its breadth should be diminished ; the space, at the centre, left uncoated with pitch, should be greatly con- tracted ; and, in the case of the little mirror, which has no perforationin it, entircly filled up; save that a small hole, ‘through the polisher, tapering, from the back of it, up. wards, to its surface, should be left, for the pitch to sink into, when it becomes closed, and too much compressed, at the centre; and the furrows, in the pitch, gradually deepened * Hereit may be proper to observe, that, as the curvature is con- stantly diminishing by the mere continuance of the operation, so the process is not to be pursued any longer, after the polish, and the desired figure, are found to be perfectcd. And the metal must always be. brought to a very fine face, anda correct spterical figure, on the hones, or on alcaden tool, bedded with the finest washed emery, before the process of polishing commences; because if all scratches, from the grinding, be not previously obliterated, the polishing must, in order to efface them, be continued so long, as ‘to diminish the curvature of the mirror beyond what is requisite; especially, if the area of the polisher be not of anoval, but of a round shape; which latter has a greater tendency, than theformer, to diminish the curvature of the mirror and to renderit hyperbolical, And the correction of ‘this, afterward, might require a troublesome alteration of the polisher, or even make . it necessary to put the metal again upon, the hones; and yet, in the Gregorian telescope, the -hyperbolic figure is the proper one, for either of the mirrors, if that of the other specelum be spherical. toward REFLECTING TELESCOPE, 93 toward the edges. I believe, that (for the reason before given) the uncoated space, at the center, ought always to be as much smaller, on every side, than the perforation in the mirror, as the greatest range of the strokes, in polish- ing, advances the centre of the mirror beyond that of the Experience polisher, having the same shape as the polisher itself; and one this that it ought to be smallest, or no other than as just men- maak tioned, when there is no hole in the mirror, _ Lhave, in this method, with certainty of success, as veri- fied by examination of the progressive change of curvature in the mirrors, from a greater degree to a less, and vice vers, effected the desired configuration of them: which serves to confirm me in the belief, that the circumstances, above pro- posed, are those which are really operative, in communicat- ing the diversity of figure to telescopic mirrors; and that neither the direction of the strokes in polishing, the size or form of the polisher, consistence of the pitch made use of, or other accidents, are of any farther moment in the pro- cess, than as they serve to modify the resistance of the pitch, in the several parts of the surface of the polisher. Whe- ther, by attention to the principles here laid down, it would be possible to produce an hyperbolic form, in the convex _mirror of the Cassegrain telescope, 1 have been prevented from endeavouring to ascertain by experiment, from those casualties, affecting my situation in life, which I have already intimated. But it shouldseem, that it would, to a certain ’ degree, be practicable, from the means I have suggested, of producing a progressive, specific alteration in the figure of the polisher; if [have judged rightly of the existence and cause of that alteration. . And if it should be found possible to give, to a convex Proposed im- speculum, an hyperbolic curvature, the same could be done ashes , tothe convex object glasses of dioptrical telescopes: which scopes. isa property still wanting to them; a want which makes them inferior to reflectors, even when they have been ren- dered achromatic, if the aberrations from their spherical figure remain, after those from refrangibility are removed : which aberrations, taken laterally, as they always ought to be, are asthe cubes of theapertures. So that, if the lineal aperture be doubled, and the light admitted, which is as the square of the aperture, quadrupled, in order to increase the te magnifying / Observation of Huygens that very small pen- cils produce indistinct Vision. The author thinks that the indistinctness arises from faults in the object-glass, and not in the eye itself ; REFLECTING TELESCOPE: magnifying power four times, (or to double the lineal -am- plification,) preserving an equal brightness in the image; ‘ the telescope must be made four times longer, that it may remain equally distinct *; an inconvenience, from which it must be very desirable to exempt this telescope, by correct- ing the figure, and, with it, the aberrations of its object glasses. - It is not the object of this essay, to investigate any parti. culars,in the construction of the telescope; (which would open a large field of inquiry ;) but to try to assist mechanical contrivance in its fabrication. 'T'o this end, I think it fit to add a remark, on the property of the pencils of rays, respecting the latitude of each of them, where they fall on the pupil of the eye; first discovered by the great Mr. Huy- gens; as I suspect that the inconvenience he mentions, as resulting from a certain breadth of the pencil, may casually exceed thelimit stated by him, and may admit of a practical remedy. He observes, that if the latitude or breadth of the pencils, at the.pupil of the eye, be very small, (so as not to exceed, if I remember right, the sixtieth part’ of an inch,) the vision, by the telescope or microscope,’ will be indistinct so tliat, unless the pencils be of greater breadth than this space, at the place of the eye, the instrument will be de- fective: and he attributes this to something in the natural conformation, or in the humours of the eye; which, conse- quently, willadmit of no remedy.: On this may I presume * Aconception of thismay be, perhaps, most familiarly acquired, by considering, that if, of two object lenses, the aperture, and also the focus of one, be twice as great as those of the other, the angles of inci- dence, and refraction, of the extreme rays, which come from a very remote object, and form the cones or pencils made by both, will be equal; and the pencils themselves, and their aberrations, will be simi- _lar figures; all the lineal measures of that of the larger lens, being double those of the other. In order, therefore, to reduce the lateral error or diameter of the circle of aberrations of the former, to an equality with that of the latter, while the aperture, which is the base of the pencil, remains double; this pencil must be made twice more narrow or acute thanbefore. And, to effect this, its length or focus (which, at first, was twice as great as that of the other pencil) must be doubled; so that now it must be four times as long as the smaller pencil; i.e. the lengths should be as the squares of the apertures. te REFLECTING TELESCOPE, 95 to observe, that the latitude of the pencil, as it enters the eye, is the same as that with which it falls on the last eye- glass; and, that the effect of it, which Mr. Huygens attri- butes to the eye, may, therefore, as naturally, be attributed to the eye-glass, as to the eye*; especially when an anato- mical dissection of it will demonstrate, that the perfect transparency ofits humours, and exquisite polish of its cor- nea, or outer coat, (not to talk of its achromatic property, ) far exceed, in this optic instrument of the Deity, any thing that can be manufactured by man. In fact, the polish given to the eye-glass, and the transparency of the glass itself, is always imperfect; and many points in its surface, which ought to serve for the regular transmission of light, will be obstructed by its roughness and Opacity ; so that, if the pencils occupy but avery little space on the lens, no points of fair transmission may there remain; and the few rays, that pass through, may be so distorted, by irregular refrac. tion, and inflection; in the glass, and in the eye-hole, that the vision must be indistinct. And this was the more likely to happen, in Huygens’s time; because, neither the fine polish- ing powder, of colcothar of vitriol, was then in use 3 (and Mr. Huygens used nothing but tripoli;) nor was the method of polishing, tal the help of BEeA; divulged by Sir Isaac AOE ae Newton. If this conjecture be right, the remedy is, to use proposes that both these helps, in communicating an exquisite polish to these should be the eye-glasses; especially the smaller one, where the Pp netics breadth of the pencils is reduced, in the same proportion as and polish. its radius, oras the increase of its magnifying power; and; also, to avoid using flint glass for this purpose; “as it is found to be the least transparent of any, as well as most dispersive. ie I may here also observe, that, as the transparency and. fence Rams« polish of glass must ever be, to a'certain degree, imperfect; sehen so the projected improvement of Mr. Ramsden, to avoid the * °°"* '™ dispersion of the rays, by throwing the image just before. the first eye-glass, is unlikely to answer: because, in this ease, each of the pencils would occupy little more than * When a white ground is viewed through a telescope which gives avery slender pencil of rays, the want of transparency in the parts of the eyc is seen by spots and other figures, which move along with that -ergan while the telescope is kept motionless. —N. a point, 96 The eommon colcothar ob- jected to. The author makes his col- cothar by REFLECTING TELESCOPE. a point, on the surface of thelens; and, if that point should be opaque, or unpolished, or covered with dust, no rays of the whole pencil could be transmitted through it: which would, probably, happen to too many of the pencils, and affect the image, which is composed of these pencils; whose latitude, therefore, ought to be greater than the limiting measure stated by Mr. Huygens. And, to effect this, with as high a charge as the instrument will bear, a part of the amplification should be thrown away, on the first eye-glass; and diminished, by shortening its focus; that the pencils being, by it, rendered more obtuse, may fall, with greater divergence, and latitude, on the second eye-glass, which may thus be made shorter, and on theeye. For it is not to be supposed, that the image, formed in a telescope, can be viewed, by a small lens, with as much advantage as an object may. The rays, from each point of the latter, fall upon the whole surface of the lens; and, therefore, a sufficient num- ber of them, to fill the pupil of the eye, must be trans. mitted ; whereas, the rays, from each point of the image, occupy only a small speck on the lens; in no-case larger, in effect, than the pupil of the eye; and must, when so con- tracted, be the more obstructed, by any imperfections in the glass. } . As, therefore, the fineness of the powder, employed in giving the highest lustre and polish to the specula, and to the cye-glasses, is of great importance, in that process : and, as I found, that the crocus, or colcothar of green vitriol, (now used, as the fittest for that end,) could seldom be procured, so free from grittiness, as to be capable of leviga- tion, to a sufficient degree of fineness ; insomuch, that I was obliged to attempt to make it myself; it may be useful to state, that, by the following easy method, I succeeded in producing some of excellent quality. Considering that the vitriol, distilled in close vessels, might probably contract this grittiness, in its calx, from an union of some of its component parts, or principles, with slowly roasting 446 water contained in the vitriol, (which is the metallic the copperas, or green sul- phate of iron. _ salt of iror,) and that this might prevent its perfect calcina~ tion; I thought it best to perform the distillatton in the open air, and to begin with exhaling the water. Accord. ingly, I commenced with slowly roasting the vitriol or cop- peras, ¢ REFLECTING TELESCOPE; i 97 peras, broken into grains as small as shot, by holding: it over the firc, ona fire-shovel, till the moisture in it appeared to be driedaway. I then putit into acrucible, and kept it~ tus uncovered, ina clear fire, till it had been some time red hot*; And levigating by which, the spirit or oil of the vitriol was distilled from. ion nag with it, and the calx or colcothar remained, of a brownish red colonr, and of a perfectly equal texture, entirely free from the hard or gritty particles ; and it was easily levigated, “when moistened with water, ona piece of looking-glass- plate, by apiece of the like glass having a handle of brass cemented toit. This furnished a very fine and impalpable powder, capable of communicating to the specula, or lenses, the most exquisiice polish and lustre +. To apply with precision, and afford a fair trial.of the Good specu- _ method of polishing I have recommended, it is necessary ane ee farther to consider, that the advantages, resulting from cor- j¢ cither the rectness of figure, in the mirrors, may be ai sia by an Sine opatly undue position of them, or of. the lenses, im the instrument, centered, or or by adefect of form in the lenses, whose edges may hap- not placed on pen to be thicker on one side than on the other; i.e. they tesameaxs may not be complete, or equally curtate segments of spheres; and, consequently, that a proper trial and estimate cannot be made, of the figure of the mirrors, unless these and the eye-glasses be right in these respects ; especially in the Gre- gorian telescope, whose adjustment is a matter of more nicety aud difficulty, than that of the Newtonian. And since, in the former, the surfaces of the mirrors and lenses ought all to have one and the same axis, viz. that of the’ instrument, in which are to be all their foci; it is necessary this should be cautiously ascertained; because contrary deviations of them, in this respect, might apparently com. pensate one another, and escape detection, though they would really be attended with the aberrations of enlarged apertures. * Isuppose that the fire ought not to be too high, or too long con- tinued in this process, lest it should convert the calx of the iron into glassy scoria. Experiments will determine the due regulatton of the heat, so as to ensure success to the operation in every instance. The heat ought to be so great, as to give the colcothar, not a brown, but 2 red colour. _t The same powder, spread on leather, would give the smoothest edge to razors and lancets, &c. Vor. XVI.—F es. 1807. I The 98 Directions for placing the mirrors. The specuhums - may be very truly set by the solar rays, REFLECTING TELESCOPE. The centre of the great mirror ought to be in the com- mon axis of the instrument; and the position of it in its cell, in thetube, may be known thus. Let the little mirror be taken out of the tube; and let the round, central dia- phragm, before-mentioned, (which ought to be made of a flat piece of tinned plate, or a brass plate, made clean and bright enough, to reflect the light strongly, but not polished,) be fastened across the mouth of the tube, exactly in the middle of it; and let a round hole be made through the plate, the centre of which shall be in the axis of the tube, and its diameter so large, as that the whole disc of the sun may be viewed through it, at the eye-hole of the telescope, when the eye-glasses are taken out. ‘Then, directing the instrument to-the sun, or the full moon, when very bright, so as that its whole dise shall be secn through the hole in the diaphragm; (using a lightly tinged screen-glass, to look at thesun;) if the light, reflected from the great mirror to the diaphragm, occupies on it, a circular area, concentrical withthe hole made at its centre, the mirror is rightly placed, and its focus is in the axis of the tube. But, if the edge of the illuminated circle approaches nearer to the hole in the plate, onany side, the same side of the mirror inclines to- ward the axis of the tube, its cell not being exactly vertical to it; or otherwise, the centre of the mirror is not in that axis, as it ought to have been. If the outer one, of the three aforesaid diaphragms, be, at the same time, applied to the mouth of the tube, so as to expose only the middle zone of the great mirror to the light; the circle of light, re. flected by it, to the central diaphragm, will appear better defined on it. But the adjustment of both mirrors and lenses may, at the same time, be proved, by the following most ‘easy an certain method, if exactly pursued : Having eroded: that the little mirror shall be so sup- ported, that its centre may always move in the axis of the. great tube; and proved that it is so, as Mr. Edwards pre- scribes, by taking off the mirror, and seeing, through the eye-tube of the telescope, (without the lenses,} that the hole, in the middle of the little round plate, to which hat mirror is screwed, concentrical with the plate, corresponds with the intersection of two cross hairs, tied diametrically across REFLECTING TELESCOPE, across the mouth of the tube: then let the little mirror be replaced, and the eye-tube taken out, and let the telescope be directed to the sun’s centre; which may be done, by the help of the little dioptrical telescope, called a finder, affixed to the instrument, if it be farnished with such; or otherwise; may be effected, with sufficient exactness for this purpose, by pointing the telescope to the sun, so as that the shadow of the little mirror may coincide with the hole, in the great mirror; which will be, when the great tube is so placed, as to project its shadow of acircular form. In these circum- stances, let the light, reflected from the little mirror, through the round perforation in the great one, be received.upon a plane, placed at some distance behind the latter, at right angles to the axis ofthe tube. Thelight will occupy a cir- cular area on the plane; and, if the centre of the light be coincident with that of the shadow of the little mirror, this mirror is not only parallel to the great one, but both are duly adjusted, at right angles, to the axis of the tube; which, also, then corresponds with their axes. But, be- cause the little mirror and its shadow, and also the cone of light, reflected from this mirror, are of greater breadth than the perforation in the great one; the boundaries of the re- Aiected light, and those of the shadow, cannot be seen wholly on the plane, through the hole in the great mirror, in any one position of the telescope, Let, therefore, the axis of the telescope be a little diverted from the centre of the sun, till the shadow of the edge of the little mirror falls within the hole in the great one: by which, some dis rect light will pass through, next the shadow, and appear on the plane, in form of a crescent: and, at the same time, the circle of the reflected light of the sun will have moved across the shadow; till, by a certain degree of obliquity, in the direction of the telescope, the edge of the circle of the re. flected light will be in contact, externally, with the crescent of the direct light. And, if the crescent be always of the same breadth, when this contact takes place, on every side, by a diverting of the telescope, from the centre of the sun, successively, in every direction; then both the mirrors are parallel, and at right angles, to the axis of the instrument. But, if the crescent be broader, in any certain position of ee the tube, when the circle of reflected light just touches its 12 edge $ | “99 100 =~ and the eye lenses after- wards set. Position of the eye-hole. REFLECTING TELESCOPE. edge; then the side of the little mirror, corresponding with that of the illuminated circle, where it is in contact with the crescent, makes too great an angle, with the axis of the instrument; and it must be reduced to a right angle, by screwing forward the adjusting screw of the little mirror, in ‘that part, having previously withdrawn the opposite screws. When the mirrors are thus found to be rightly placed, and the eye-tube and lenses are restored to their places; if the whole image, of the great mirror, be not Visi- ble in the eye-hole,.when this is in the common axis of the instrument, then the lenses are defective; either, some of them, or some of their surfaces, or the tube they are fixed im, being inclined to the common axis; and, by this means, aistorting the cone of rays, from it. Which irregularities must be rectified, before a true estimate can be formed, of the correctness of the mirror’s curvature. The distance from the smaller lens, at which is the point of decussation of all the pencils of light, and the place where the cye-hole ought to be, may also be most easily and most accurately found, by directing the telescope to the sun, having taken off that part of the eye-tube behind the lenses; and Jetting the light fall on a plane, moveable back and forward, behind the second cye-glass, and kept at right angles, to theaxis of the specula and lenses; the place, at which the image of the great mirror, with the shadow of the little mirror described on it, is seen most distinctly formed on the: plane, ought to be the place of the eye- hole, ELEOTRIC LIGHT. 1 01 LiViorsis ti ihsi Hey lisa On the Absorption of Electric Light by different Bodies, and some of their Habitudes with respect to Electricity. \ Ina Letter from Mr. Wu, Sxrimsuire, Jun. , Communicated by Mr, Curuzertson. y vn Wisbech, Jan. 14, 1807. Dear Sir, As you thought my former account of some electrical ex- Phosphores- periments on the phosphorescency of calcareous substances cence of bodies worth sending to Mr. Nicholson’s respectable and valuable ik ia Journal, I now trouble you with a second letter, contain~ ing the results of other experiments, made with the same view, upon the different species of the remaining earths that were within my reach. But I do not intend to stop here.— And as I perceive the chief value of my inquiries will rest, upon their being a dépdt of numerous facts, whereon other philosophers may more successfully build than my abilities will enable me to do, it becomes necessary for me in this, and any future communication upon the same subject, to speak more in detail than I at first intended. If in this state, you should still think them worth public attention, I shall be glad to see them inserted in the Philosophical Journal. Barytic Genus. Carbonate of barytes afforded no spark, but was very Barytic com- luminous when the shock was passed above it, though the pounds. “Jight was of short continuance. Sulphate of barytes.—The several specimens of this sub- stance, which were subjected to experiment, were all lumi- nous by the electric shock, but were not so brilliant as the carbonates; they also differed from them in giving very good sparks when placed upon the prime conductor; except some specimens, consisting of small crystals, which acting as so many points, gave out the electric fluid to the atmosphere, and would not allow a spark to be taken from them, It is curious, and worthy observation, that in these two barytic species the facts turn out exactly the reverse of what takes place 102 Sulphuret of barytes, Muriatic genus, Mica gives sparks, ELECTRIC Licur: place in the calcareous genus, in which the carbonates give sparks, though they are slightly luminous, compared to the sulphates, which are brilliantly phosphoric, but afford no spark; whereas in the ‘barytic genus the carbonates are beautifully luminous, but give no sparks, while the sulphates afford good sparks, butare slightly phosphorescent. Sulphuret of barytes was but slightly luminous by the electric explosion ; in which it essentially differs from the sulphuret of lime *, which is the most brilliant phosphorus, both by the electric and solar light, that I have yet seen. _ Muriatic Genus. Magnesia, pure, and carbonated, were both luminous by the electric explosion ; the light, however, continued but for a short time. Sulphate of Magnesiais very luminous through its whole substance. Sulphuret of Magnesiais luminous, but not more so than the carbonate. ; ) Turkey tobacco-pipes.—The bowls of these articles af- forded tolerable sparks, but were scarcely luminous, except in the track of the electric fluid, when the points of the discharging rods rested upon thesurface. ! ‘Chlorite gave sparks, which, upon its surface, branched off in minute, different-coloured points, something similar to, though not so brilliant as, the spark taken from any lac. quered substance, such as gilt leather, or lacquered wooden ornaments. ‘The explosion rendered it luminous. Steatites, Talc, and fibrous Amianthus, gave sparks, and were slightly luminous by the explosion. Asbestus.—A thin polished slab of this stone gave sparks similar to Chlorite, but the ramifications upon its surface were more numerous, and more variegated. _ Mica affords sparks, but I could not observe it luminous by the explosion, When held in the hand it allows the sparks to run along its surface, to strike the finger at a con, * Canton’s phosphorus is so readily illuminated by electricity, that alarge lump, newly made, partaking of the exact shape of the cru- cible, and having never been exposed to light, being placed upon the prime conductor, was beautifully bespangled with brilliant spots, merely by taking the spark from various parts of its surface, “sme 3 siderable z ELECTRIC LIGHT, siderable distance, and to which it gives the sensation of a shock, rather than that ofa spark. When the ‘shock is pissed along its surface, the fluid leaves an indelible: mark, similar to its effect upon glass. Micaceous Schistus gave a spark, which was ramified upon the surface of the stone, andsomewhat more coloured than in the Chlorite. It was scarcely phosphorescent, except in the track of the electric fluid. Argillaceous Genus. 103 Adin affords a purple spark, which is rather ramified upon Argillaceous its surface. It is luminous through its whole substance, 8°°¥% when the explosion is made above its surface; but it is shat. tered to pieces when the shock is passed through it. Pipe-clay gave a spark, and was luminous by the explo- sion; but when it was formed into tobacco-pipes, and. baked, it was scarcely if at all luminous, though it con- tinued to afford sparks. A greenish, foliated clay, found near the surface of the ground at Derby, gave a tolerably good spark, and was very phosphoric by the explosion taken above it. The luminous track left by the electric fluid, when the points of the dis- chargers rested upon the surface, continued several minutes. A blueish clay *, dug at Wisbech, and provincially termed Gault, or Golt, affords a spark, and becomes luminous by the explosion. Slate clay, or Shale, affords a spark, and isluminous; but from trials made with different specimens, it appears to lose its power of absorbing teh in proportion as it becomes bituminous +. Slates.—All the slates afforded sparks, and absoabed nd This clay, which is frequently dug inthe Fens, near Wisbech, con- tains sulphur, and if, when fresh dug, it be held before a fire, it gives out @ strong suffocating odour of sulphurous acid. -+ At the time of writing the above observation on bituminous shale Thad not the most distant recollection of a paper on ‘the light of natural phosphori, by M. Carradori, translated in an early number of the Philosophical Journal, where it is mentioned, that luminous rotten wood, and other such like substances, ‘‘ become phosphorescent in proportion as they have lost their inflammable principle, and that the property of ‘absorbing, and retaining the light, depends on that cir- cumistance.’’Nicholson’s Journal, gtoseries, Vol. lI p. 135. 2 electric f 104 Argillaceous genus. ELECTRIC LIGHT, electric light from the explosion. But a slate used in this’ neighbourhood, brought from Colly Weston, in Northamp- tonshire, and which. effervesces with acids, is by far the most beautiful. -When the shock is taken above the centre of a piece some inches.square, not only the part immediately be- low the rodsis luminous, but the surface of the slate appears bespangled with very minute brilliant points to some distance from its centre; and when the points of the dischargers rest upon the surface of the slate, these minute spangles are de- tached, and scattered. about the table in a luminous state. The eck of light between the rods continues ga aaa cent. several minutes. Hone stone, of adirty greyishcolour, gave a geind nei te and was phosphoric by the explosion. Fuller’s Earth gave a good bright spark, but was very slightly luminous, cxcept im the track the fluid = in its passage from one rod to the other. Reddle gave no spark, but a purple stream, attended with avery sharp hissing sound. It was rather more luminous than Fuller’s Karth. ‘z Armenian Bole affords a spark, which is ramified upon its surface:, Itis not luminous by. the electric explosion; even’ when the points of the dischargers rest upon it, no track of light is visible; but several minute fragments are iagitnkes from its nN Terra Sigillitica of the shops gives a apart ‘and is phos- phoric after the explosion. Basalt gives sparks which are radiated upon its surface, but not ramified as in Chlorite and micaceous Schist. It was phosphoric only in the track formed by setae the dis- chargers upon it. Bricks of various kinds afforded small purple sparks, of a bright red colour onthe surface. They were very slightly luminous by the explosion; but afforded a bright track of light between the points of the dischargers when en rested upon them. Tiles of different kinds: afforded similar uh to ‘the aaa except that most of the tiles were rather more luminous than the bricks, when the electric explosion was madeabove them, especially a yellow tile, with a redish tinge in the fracture, which, from its greater phosphores= cence, , ELECTRIC LIGHT. cence, and its slightly effervescing with: acids, I suspect to contain more calcareous earth in its composition than the others. - Queen’s ware, glazed, gives a good spark, which is flame coloured, and radiated on its surface; but it is not phos- phoric. When fractured, the unglazed surface affords a purple spark, and is luminous by the shock. All the different kinds of Pottery-ware which I tried gave the same results, except slight varieties in the colour of the sparks: anda common dirty white ware, which was lumi- nous on its glazed surface when the shock was passed above it. From what I have hitherto observed, | am induced to believe that all glazing, in which a metallic oxide is used, is not phosphoric, but gives a good spark. Allunglazed Pottery is luminous by the explosion, and gives a vivid track of light when the dischargers rest upon its surface. Siliceous Genus. _ Rock Crystals wereall phosphoric by the explosion ; and Siliceous some of them that had two or three particles of ore upon 8"™* their surfaces, were transparent by the spark when it passed from the ore to the knob of the discharging rod, otherwise: the crystals gave no sparks, but merely a hissing stream. A rhombic crystal was rendered luminous through its whole substance by the explosion, retaining its light several minutes. At the instant after the explosion it emitted a red light, but which very soon became white. Siliceous sand, washed and dried, was not luminous, ex- cept where the points of the dischargers were in contact ’ with it. Quartz is phosphoric, and shines with a uniform dull white light. It gives a purple stream instead of a spark. After the explosion it affords the same odour as when two pieces are rubbed together. Flints afford small purple sparks, both from the external coat and the surface of the fracture. The explosion does not render them so luminous as Quartz, but the external coat is more phosphorescent than the fr acture, ees | in the track of the discharge. Vou. XVI.~—F rz, 1807, K. taki 105 106 Siliceous genus. f£LECTRIC LIGHT. Lapis Lazuli affords a very good spark, and is luminons by theshock. Egyptian Pebbles, Scotch Pebbles, Felspars, Agates, Calcedonies, Carnelians, and Jaspers, gave hissing purple sparks, and were luminous by the explosion. Several of these substances give out the same odour as when two pieces are rubbed against each other. Porphyries and Granites gave a hissing purplespark, and were luminous by the shock, which, when passed upon the surface, produced avery bright track of light, which in some specimens, especially in a piece of whitish Granite, continued luminous for several minutes. Pudding Stones gave a similar hissing spark ; and the oval pebbles being more luminous than the siliceous sand, in which they are imbedded, were readily distinguished in the dark when the shock was passed above the surface of the stone. Mochoas gave very good sparks from the arborescent parts, but only a hissing stream from the stone itself, which is slightly luminous by the shock, but affords a bright track of light between the ends of the discharging rods. The Yorkshire Stone, which is used for flat pavement, gives a purple spark, and seems to become luminous by the electric explosion, in proportion as it partakes of a calca- rcous nature, for those specimens which are verging toward. micaceous schist, (and in which I have found lamina of sul- phur nearly the tenth of an inch thick,) are scarcely at all Juminons, : Pumice Stone on some parts of its surface gave only a hissing stream, but on others very good sparks, which ap- peared to penctrate through its substance, as if it contained some metallic particles within it. ‘The shock rendered it slightly luminous, but it afforded a very bright track of _ light along its surface, between the ends of the dischargers. The semivitrified ashes of a Haystack, which was con- sumed by spontaneous combustion, gave only a hissing stream, aud was slightly Juminous by the electric explosion ; but when the shock was passed upon its surface it afforded a bright track of light. Various kinds of Glass are not luminous, neither do they give MARINE ‘BAROMETER. 107 give aspark. But the dark green glass of which wine bottles are made, when by exposure to air and moisture, or under other circumstances which may enable it to reflect the prismatic colours with brilliancy, is capable of giving @ spark, and emitting light, after the electric explosion has been made above its surface. Strontian Genus. Native Carbonate of Strontites, instead of a spark, gave grrongian only a hissing purple stream, but was very luminous by the genus. explosion. ; I remain, Your’s, &c. W. SKRIMSHIRE, Jun. a V. Observations upon the Marine Barometer, made during the Examination of the Coasts of New Holland and New South Wales, inthe Years 1801, 1802, and 1803. By Marruew Fuinvers, Esq. Commander of his Majesty’s Ship Investigator, Ina Letter to the Right Hon. Sir Josppn Banks, Bart. K.B. P.R.S. &c. Sc. &c. From Philosophical Transactions for 1806. Isle of France, Aug. 19, 1805. A FORE-KNOWLEDGE of the wind and weather isan Great advan- object so very interesting to all classes of men, and the tages ofa fore» changes in the mercurial barometer affording the means nema: 7 which appear most conducive to it, a system that should The barometer with certainty explain the connection between the variations indicates it. of the mercury and those in the atmosphere under all cir. cumstances, becomes gready desirable; to seamen, more especially, whose safety and success depend so much upon being duly prepared for changes of wind, and the approach. ing storm, it would bean acquisition of the first importance: in a more extended view, I may say, that the patriot and the philanthropist must join with the philosopher and the mari- ner in desiring its completion. Sa long and widely-extended ‘a course of observation, however, scems requisite to form a K 2 even 4 108 MARINE BAROMETER. even a basis for it, that a complete system is rather the object of anxious hope than of reasonable expectation. Much has been donc toward it, but so much appears to remain, that any addition to the common stock, however small, or though devoid of philosophical accuracy, I have thought would be received by the learned with candour. With this prepos- . session, I venture to submit to them some observations upon The land and s€a winds are more particu- Jarly indicated, and also their strength. the movement and state of the mercury upon the coasts of New Holland and New South Wales, the Terra Australis, or Australia, of the earlier charts. The principal circumstance that has led me to think these observations worth some attention, is the coincidence that took place between the rising and falling of the mercury, and the setting in of winds that blew from the sca and from offthe land, to which there seemed to be at least as much reference, as to the strength of the wind or state of the at- mosphere; a circumstance that I do not know to have been before noticed. The immediate relation of the mest mate-. rial of these facts, it is probable, will be more acceptable than any prefatory hypothesis of mine; and to it, therefore, I proceed; only premising, that a reference to the chart of Australia will be necessary to the proper understanding of some of the examples. My examination of theshores of this extensive country began at Cape Leuwen, and continued eastward along the south coast. _ In King George’s Sound, December 20, 1801, after a gale from WSW, the mercury had risen from 29,42 to 29,84, and was nearly stationary for two days, the wind being then moderate at NW, with cloudy weather. On the 92d, the wind shifted to SW, blew fresh, and heavy showers of rain occasionally fell; but the mercury rose to 30,02, and remained at that height for thirty hours; and on the weather clearing up, and the wind becoming moderate in the same quarter, it rose to 30,28. G Fresh breezes from E and SE caused a rise in the baro- meter in King George’s Sound, once to 30,20, and a second tine to 30,18, although the Bak ee at these times was hazy: but with Hight winds from the same direction, which were probably local sea breezes only, the mercury stood about 29,95 in that neighbourhood. od Example, Jan. 12, 1802, in Dilipasassiaitiols acide pelago, MARINE BAROMETER. pelato, the mercury rose to 30,23, previously to a fresh breeze setting in from the eastward. In the evening of the 13th it blew strong from ESE, with hazy weather, anda rapid fall of the mercury to 29,94 had then taken’ place ; but instead of the wind increasing, or bad weather coming on, the wind died away suddenly, and a light breeze’ came off the land at midnight, with cluudy weather. At the Cape of Good Hope, which is nearly in the same Jatitude, the mercury rises with the fresh gales that blow there from the SE in the summer season. The weather that accompanies these south-east winds, is nearly similar in both places; thé atmosphere being without clouds, but contain- ing a whitish haze, and the air usually so dry as sensibly to atiect the skin, particularly of the lips. 3d. Jan. 22. Three degrees east of the Archipelago, the mercury fell with some rapidity down to 29,65 with the wind trom ESE. It was eight o’clock at night, and we prepared ior a gale from that quarter; but at ten, the wind suddenly shifted to WNW, coming very light off the land. On its veering gradually round to SSW, clear of the Jand, at noon, 23d, it freshened, and the weather became thick ; yet the mercury had then risen to 29,84, and at cightin the evening to 29,95, though the wind then blew strong. It continued to rise to 30,16 as the wind shifted round to SE, and fine weather came on; but on the wind passing round to ENEand NNE, which was off the land, the mercury fell back to 29,73, though the weather was fine and the wind moderate. On a sudden shift of wind to the SW, a fresh breeze with hazy weather, it again began to ascend, and a similar routine of wind, producing nearly the same effects upon the barometer, again took place. The effect of sea winds in raising the mercury, in epposition to a strong breeze, and of Jand winds in depressing it, though they were light, was here exemplified in two remarkable instances, 4th. Inthe neighbourhood of the Isle of St. Francis of Nuyts, longitude 1334° east of Greenwich, we experienced a considerable change in the barometer. For nine days in January and February the wind continued to blow con- stantly, though moderately, from the eastward, mostly from theSE. It appeared like a regular trade-wind or monsoon, -but so far partook of the nature of sea and land ‘breezes, as commonly 109 Observations and inferences to ascertain the correspon- dent changes of wind and weather to be expected after change in the marine baro- meter, 110 MARINE BAROMETER, Observations commonly to shift more to the southward in the day, an:l te andinferences blow more from east and NE in the night. The weather was to ascertain F the correspon- Very hazy during these nine days; so much so, that for six dent changes, of them no observation of thesun’s altitude, worthy of con. of Bia ad fidence, could be taken from the sea horizon, although the expected after Sun was sufficiently clear; and in the whole time, the mer- change shah cury never once stood so high as 30 inches, but was fre- Bhs A quently below 29,70. I considered this to be the more ex- traordinary, as settled winds from the eastward, and especi- ally from SE, had before made it rise and stand high upon this coast, almost universally, even when there was a consi- derable degree of haze. The direction of the south coast, beyond the Isle of St. Francis, and even abreast of it, was at that time unknown to me; but I then suspected, from this change in the barometer, that we should find the shore trending to the southward, which proved to be the case. The easterly winds, then, whilst they came off the sea, caused the mercury to rise upon the south coast ; but in this instance that they came from off the land, they produccd a contrary effect ; but it is to be observed, that the most hazy part of the time, and that during which the mercury stood lowest, was two days that the wind kept almost constantly on the north side of west, more directly off the land: its height was then between 29,65 and 29,60. The haze did not paniitiel a away on the wind shifting to the westward; notwithstanding which, and that the new wind rose to a strong breeze; and was accompanied with squalls of rain, the mercury began to ascend, and ‘had reached 29,95 when the squalls of wind. and rain were strongest ; the direction of the wind being then from SSW. On its becoming moderate, between SSW and SSE, the mer, cury ascended to 30,14, and remained there as long as the. wind was ne ieee 5th. Going up the largest of the two inlets on the south coast, in March, we were favoured with fine fresh breezes from SSW to SSE, sometimes with fine, sometimes with dull weather, the mercury rising gradually from 30,08 to 30,22. In twenty-four hours afterwards, it fell below 30 inches, and a light breeze came from the northward, off the land, with finer weather than before. The mercury continued i fall to 29,56, where it stopped ; the wind having then ceased to blow TPiACLAAGS MARINE BAROMETER. iL. blow steadily from the northward, and become variable. In Observations twenty-four hours more, the wind set in again to blow fresh se ai no from the southward, the mercury having then returned to the correspon- 29,94, and itwas presently up to 30,22 and 30,28. It kept jaar ore nearly at this height for several days that the southwardly ..,therto be” wind blew fresh, but on its becoming lighter, and less steady expected after in its direction, the mercury descended; and in the calm pga ae i which followed, it had fallen to29,90. This example affords meter. clear proof of afresh wind from the sea making the mercury rise, whilst a light wind off the land, with finer weather, caused it to descend. 6th. ‘The calm was a prelude to a fresh gale; but the mercury began to rise at eight in the evening when it had just sprung up; by the next noon it was at 30,10 when the wind blew strongest, and in the evening at 30,22. This gale began as gales usually, if not always do upon this coast, in the north-west quarter, and shifted round to SW and SSW ; _but quicker than I have generally seen them: there was no rain with it, nor was the atmosphere either very hazy or cloudy*. The mercury continued to rise till it had reached 30,25, and then was stationary as long as the wind remained between south and west; but on its veering round to the eastward of south, a second rise took place, and for forty hours the mercury stood as high as 30,45, the wind being then between SE by S and east: the weather was very dull and hazy during the first half of these forty hours, but finer afterwards. As the winds between SE by Sand east slanted off the main land, this example seems to be in opposition to the 4th, and leads me to think, that it might have beer the ‘yery extraordinary kind of haze, and perhaps some peculia- rity in the interior part of the land abreast of the Isle of St. Francis that in part occasioned the fall of the mercury with south-east winds ; as much, perhaps, as the circumstance of the wind coming from off the shore. ' After this rise in the mercury to 30,45, it fell gradually ; but, for thirteen days, kept above 30 inches, the winds being generally between SE and SW, but light and variable, and the weather mostly fine. . , * Tafterwards learned from Captain Baudin, that this gale’ was much heavier in Bass’ Strait than we felt it at Kanguroo Island. 7th 112 Observations and. inferences to ascertain the correspon- dent chariges of wind and weather to be expected after change in the marine baro- macter, MARINE BAROMETER, 7th, North-eastwardly winds, off the land, were the next that prevailed ; they were light, and accompanied with cloudy weather and spitting rain. The mercury fell to 29,70, and remained there till the wind shifted to the west and southward, when it began to rise, and in two days was up to 30,42, At that time we were off the projection marked II. in the chart, in 1394° east longitude ; the wind had then veered to the epee es idl along the shore, with a steady breeze, and the mercury remained nearly stationary so long as it lasted ; but on the wind dying off, and flawing from one side to the other, it descended quickly to’ 30 inches. A breeze then sprung up at NW, which, within twenty-four hours, shifted suddenly to SW, and blew a gale which had ~ near proved fatal to us. It was accompanied with rain and very thick weather, and lasted two days; by which time, the mercury had descended to 29,58. 3 8th. In Bass’ Strait, for Lan days in the month of April, the mercury stood above 30,40 with the wind from the south and eastward, sometimes blowing fresh: the weather generally fine. It then fell half an inch in eight hours, anda wind set in soon after from the north-westward which continued four days, blowing moderately, with cloudy weather, and sometimes a shower of rain; the mer- cury remaining stationary between 29,83 and 29,89. On thissecond wind dying away, a strong breeze sprung up which fixed at WSW with squally weather; but for three days no alteration took place in the barometer, until the wind shifted to NW and north, and the mercury then descended to 29,52, though the gather was finer, and wind more moderate ches before. 9th. Passing along the south coast of Australia the second time, we experienced light winds from the sea for forty hours in D’Entrecasteaux’s Archipelago, in the month of May: they were variable between WSW and SSE with dull cloudy weather, and the mercury stood very high, being up to 30,50 most of the time. The wind then came ‘round to N by E and NNW; previously to which, the mercury began to descend, and it kept falling for two pie till it reached 30,19 Rheeeh the weather was not so cloudy as before, and the find was equally light. On the wind — vecring to west and WSW the mercury rose te 30,25 ; but it MARINE BAROMETER. it now came on to blow fresh, with squally thick weather, yet the mercury continued nearly stationary for twenty- four hours, appearing to be kept up in consequence of the wind having shifted round to SSW, more directly from off the sea. On its increasing to a gale, however, there was a pretty rapid descent in the barometer to 29,96; but the ascent again was equally rapid, and to a greater height, on the wind becoming moderate. Ina short calm that succeed- ed, the mercury stood at 30,42, but on the wind setting in from the north, which was from off the land, it fell to 30,25,. and remained there two days: we had then reached Bass’ Strait. From these examples upon the south coast, it appears, generally, that a change of wind from the northern, to any point in the southern half of the compass, caused the mer- cury to rise, and a contrary change to fall; and that the mercury stood considerably highcr when the wind was from the south side of east and west, than, in similar weather, it J 11S Observations and inferences to ascertain. the correspon- dent changes of wind and weather to be expected after change in the marine baro- meter. did when the wind came from the north side ; but, until it is - known what are the winds that occasioned the mercury ta ascend, and what to descend, upon the other coasts of Australia, it will probably be not agreed, whether it rose in consequence of the south winds bringing in a more dense air from the polar regions, and fell on its being displaced by that which came from the Tropic;—or whether the rise and higher standard of the mercury was wholly, or in part, occa~ sioned by the first being sea winds, and the descent because those from the northward came from off the land. The height, at which the mercury generally stood upon — the south coast, seems to deserve some attention. It was very seldom down to 29,40, and only once to 29,42. Of one hundred and sixty days, from the beginning of Decem- ber to May, it was nearly one-third of the time above 30 inches; and the second time of passing along the coast, _ from the 15th of May to the Ist of June, it only descended to 29,96, and that for a few hours only, its average standard _ for these sixteen days being 30,25. Upon the eastern half of the coast, beyond Cape Catastrophé, in March, April, and May, the mercury stood higher than it did on the western half in December, January, and February: the average standard of the first was 30,09, but that of the © ~ Vor. XVI.—F rs. 1807. L latter 114. MARINE BAROMETER. Observations" latter only 29,94. At the Cape of Good Hope, the mean andinferences height in the Darron during eighteen days in October to ascertain the correspon- and November, was 30,07. dent changes of wind and weather to be expected after ‘change in the marine baro- meter. o The marine inf ometer on board the Investigator, supplied to the astronomer by the Board of Longitude, was made by Nairne and Blunt, and had, I believe, been employed in one or more of ne voyages of Captain Cook, and perhaps in that of Captain Vancouver. I suspect, that it was not suspended so exactly in the proper place, as the latter instru- ments of these makers probably are; on which account, the motion of the ship cansed the mercury tostand tod fel and perhaps one or two-tenths of an inch might be deducted with advantage from the heights taken at sea, but I think hot when the ship was lying steadily at anchor in the harbour. The barometer stood in my cabin, and the height of the mercury was taken at day-break, at noon, and at eight in the evening, by the officer of the watch; as was also that of the thermometer. The general effects produced upon the barometer by the sea and land winds, on the east coast of Australia, will be learned from the following abridgment of our meteorological journal : ist. In the run from Cape Howe, in 371° south latitude, to Port Jackson, in 34°, once in the month of May, and once in June, I found that the mercury descended with light winds from north, NW, west, and WSW =; whilst during fresh breezes from south and SW it ascended, and steod considerably above 30 inches; with the wind at NE and NNE it also kept above 30 inches, but not so high, nor did it rise so fast, as when the wind was from SSW. From between south and east, the winds did not blow during these. times. ‘This example does not differ so much from those on the south coast as to be decisive of any thing. 2d. The observations made during a stay of ten weeks at Port Jackson, in May, June, and July, 1802, are more in point than almost.any other. ‘Strong eastwardly winds — were very prevalent at that time, and were almost always accompanied with rain and squalls; yet this weather was foretold and accompanied by a rise in the barometer, and the general height of the mercury during their continuance was 40, 20: higher if the wind was on the south side of ESI, and ‘lower a MARINE BAROMETER. i 15 lower if on the north side of east. The winds from south observations and SSW, which blow along the shore, kept the mercury up and inferences to about 30,10, when they were attended with fine weather, - Baya as they generally were; but if the weather was squally, dent changes with rain, is stood about 29,95. During settled winds from ° Paloma pel between WNW and SW, With fine weather, the mercury antleciea wiheeat generally stood very “sc down at 29,60 *; and what is change in the more extraordinary, when these winds were less settled, and poof at the weather dull, with rain occasionally falling, the range of the mercury was usually between 29,80 and 30,10; nearly the same as when th: wind was at SSW. with similar weather ; the reason of which may probably be, that at some distance to the southward. these westwardly winds blew more from the south, and were turned out of their course, either by the mountains, or. by meeting with a north- west wind farther to the northward. Lhe winds from north and NW blew very seldom at this time: the mercur y fell on their approach. To the state of the mercury during our second stay at Port Jackson, in July, 1803, and part of June and August, it is not in my power to refer, as I’ have not been able to obtain that part of my jonrnal from General De Caen. The effects of some winds upon the barometer in this 2d example, are considerably different to what they were upon the south coast. The wind at WSW or SW with fine weather, had always caused the mercury to rise and stand high, and those from the NX to fall; whereas here, the eiiects of those winds were almost directly. the reverse, The winds from SSW, $i, and as far as east, made it rise on both coasts, with the exception of the 4th example on the south; and from between north and WNW the mercury _ fell in both cases and-stood low. 3d. Steeringalong the east coast, from Port ; Jenin to the northward, in July, we had the winds usually be- ‘+ My friend Colonel Paterson, F.R.S. commander of the troops at Port Jackson, in judging of the approaching weather by the rise and fall in his barometer inthe winter season, told me, that he had adopted arule directly the reverse of the common scale. When the mer eury rose high, he was seldom disappointed in his expectation of rainy, bad weather; and when it fell unusually low, he expected a continuance of fine, clear weather, with westwardly winds. : = L2 tween 116 Observations and inferences to ascertain the correspon- dent changes of wind and weather to be expected after change in the marine baro- meter, MARINE BAROMETER. — tween south and SW, and sometimes WSW, the mercury being nearly stationary at 30 inches; but meeting with a spurt of the south-east trade wind in latitude 24°, we found it rise to 30,30 for two days. A westwardly wind brought it back:te 30 inches for a short time; but on the trade wind finally setting in, it fixed itself between 30,20 and 30,30, as long as the wind preserved its true direction. 4th. The month of September, 1802, and the greater part of August and October, we spent upon the east coast between the latitudes 23° and 17°. The south-east trade is the regular wind here, but we had many variations. Whilst the trade prevailed, the average standard of the mercury was 30,15, and the more southwardly it was, and the fresher it blew, the higher the quicksilver rose, though it never excecded 30,30. When the trade wind was light, » it was usual for a breeze to come off the land very early in the morning, and continue till eight or nine o’clock ; but these temporary land winds did not produce any alteration in the mercury, which kept at these times about 30,10. When the trade wind veered round to ENE, or more northward, which was not seldom, the mercury ranged between 30 inches and 30,10; and when a breeze from north or N by W prevailed, which was the case for a considerable part of twenty days we remained in Broad Sound, its height was something, but not much less. These northwardly winds 1 take to have been the north-east wind in the offing ; which had been partly turned, and in part drawn out of its direction, by the peculiar formation of this part of the cast coast. There are but few instances of any steady westwardly wind prevailing; when such hap- pened, they were generally from the north side of west ; and at these times therange of mercury was between 29,95 and 30,05, which was the lowest I at any time ‘saw it on this portion of the east coast. ‘Che barometer was of great service to me in the inyesti- gation of this dangerous part of the east coast, where the ship was commonly surrounded with rocks, shoals, islands, or coral reefs. Near the main land, if the sea breeze was dying off at night, and the mercury descending, I made no scruple of anchoring near the shore; knowing that it would either be a calm, ora wind would come off the land; but if MARINE BAROMETER. 1 17 if the mercury kept up, I stretched off, in the expectation Observations that it would freshen up again ina few hours. Amongst pines oe the barrier reefs, when the wind was dying away, the baro- |, correspon- meter told me, almost certainly, from what quarter it would — next spring up. If the mercury stood at 30,15, or near it °° WNT 40S and was rising, I expected the proper trade wind ; and if expected after higher, that it would be well from the southward, or would pgs mins blow fresh; and if it was up to 30,30, both. The falling | cter, of the mecury to 30,10 was an indication of a breeze from the north-eastward ; and its-descent below 30 inches that it would spring up, or shift round to the westward. This regularity of connection between the barometer and the direction of the wind, is perhaps too great to be expected at a different time of the year; and it is probable, that we should not have found it continue so strictly, had our stay amongst the barrier reefs been much prolonged. 5th. Leaving the east coast in the lat. 17° south, we steered off to the northward for Torres’ Strait, in the latter part of October. As we advanced northward, I found the mercury Stand gradually lower with the same kind of wind and weather. The difference was not material till we reached the latitude 13°, but afterwards, the south east wind which had before kept the mercury up to 30,15, then permitted it to fall to 29,90; and the winds from ENE and NNE to 29,85. Was this alteration owing to the want of density in the air brought in by the south-east winds, in this lower latitude ?—to our inofeased distance from the land ?—or a was it, that the south-east wind was no longer obstructed -by the coast, having a passage there through Torres’ Strait ? , Fd _ , The difference between the height of the mercury, during @ north-east and a south-east wind, was much less here than _ before, although the weather was most unfavourable during the time of the north-east wind, and should have increased the difference in their effects. Was this owing to the gene- ralapproximation to that equality which has been observed to take place.in the barometer, in very low latitudes ?—or that the north-east wind, still meeting with resistance from the coast, had one cause for keeping up its power, which the south-east wind had lost? Ina general summary of the winds on the east coast, / those Tis Observations and inferences to ascertain the correspon- dent changes of wind and weather to be expected after change in the marine baro- meter, ' MARINE BAROMETER. . those that came from between south and east caused the mer- cury to rise and stand highest, as they had also done upon the south-coast, with the exception of the 4th example. The winds from NE kept the mercury up above 30 inches on the east coast, and caused it to rise after all other winds except those from the southeeastward; but on the south coast, the mercury fell with them, and stood considerably below 30 inches ; because, as it appears to me, they then came from off the Jand. During north-west winds, the mercury stood lower than at any other time upon both coasts ; and on both they came from off the Jand. | Moderate winds from the south-westward, with fine weather, caused a descent of the mercury on the east coast ; and during their continuance it was much lower. than with winds from the north-eastward ; but upon the south coast it rose with south-west winds, a stood much higher than when they came from the opposite quarter. For this change I cannot see any other reason, than that the wind, which blew from the sea upon one coast, came from off the land in the other. Although the height of the mercury upon the south coast of Australia was, upon the average, considerably above: the medium standard 29,50, it was still greater upon the east: coast: I cannot fix it at less than 30,08 or 30,10, whereas upon the south coast, I should take it at 30 inches; both subject to the probable error of one or two-tenths of an inch in excess. This’superiority seems attributal to the greater prevalence of sea winds upon the east coast, and particularly of those from Sit, which, whew all other circum. stances. are equal, I have observed to raise the mercury higher than any other on this side of the equator, analogous to the effect of north-east winds in the northern hemisphere ; and perhaps also, the superiority may be in part owing to the east coast having a more regular chain of higher moun. tains running at the back of, and parallel to it, which presents a greater obstruction to the passage of the wind over the land, than it meets on the south coast. (To ke Continued) \ INVISIBLE GIRL, VI. Letier from « Correspondent, on the Exhibition of the Invisible Girl. Fo Mr. Nicyonson. Sir, Bristol, Jan. 9, 1807. "Ture account of your correspondent X. of the manner in which the Invisible Girl amused the lounging public, ex- actly agrees with one which I sent to Mr. Walker, of Con- duit Street, about two years ago, except that X. seems to have failed, as I did, in discovering the mode by which ‘she saw the company ; for one cannot.be satisfied with being told, that ‘* a small hole closed with glass is left through ‘¢ the tunnel and side-wall of the room;” having carefully examined the room of that exhibited at Bristol, and ascer- tained that there could be no such aperture. Besides, we know that to see through any hole of a very small size the division must be nearly as thin as a shect of paper, and a hole through a tunnel and side-wall must have been very long, indeed much too long tosee people through. As my - friend never answered that letter, [ concluded that he either doubted of my account being the true one, or that he could not explain satisfactorily how the view of the company was acquired at Charles’s exhibition; although he would not have been long at a loss to invent some expedient, had it been worth his while. 119 Confirmation of the former explanation of the Invisible Girl. Question, How did she sce thg- company? ‘ In fact, thinking it might hurt the harmless exhibitors, or Account of av Jessen the amusement of the public, I desired that account exhibition a8 might not be published, unless necessary to prevent super- stitious uses being made of the trick ; and, after all, we lose | by all these discoveries when made public, much innocent pleasure, as I well remember was the case when Mr. Thick. ness unveiled some such exhibitions. That which I saw at Bristol and Bath had a loose rail with eight legs; seven of which the operator always removed from their places to blunt suspicion, but the eighth I always found immoyably fixed, and that was ever the leg toward the cloget where the lady sat who directed us. Mis Bristol, 120 NEW BALANCE. His rail also was covered opposite the mouths of his trum- pets with stained paper; but you could feel the vibration on the holes when any one answered, and peoples’ hands had a little indented them by accidental pressure. As to a small camera, I do not think it was ever used here, or at all neces- sary for the lady, asa yard of tube with a trumpet mouth would have answered all the purposes: as, however, you have been at the pains of satisfying the general curiosity in so handsome a manner, excuse me if I request. your corres- pondent to complete the instrument by disclosing what he actually knows of the mode of complete vision by direct or indirect reflection ; being always, Sir, fs Your’s, N G.C. P.S. You have omitted thrce leticrs in the diagram of the perspective lines. Vil. Descripiion of a new permanent Compensation-Balance for a Time-keeper. By Mr. Wu. Harpy*. Description of WV : cure i two compensa- E have at present two compensation-balances ; one tion balances sourt consists of several slips of brass and steel soldered, or a gas in fluxed together, and disposed in form of two S$ §’s on the é balance, but this is almost now out of use. The other is a - steel balance, having a rim of brass fluxed upon its outside, and cut open in two or three places, with sliding weights ou the rim, to increase or diminish the effect of the balance. ‘The nature of the balance (the only one now in use) is wel known, as well as its defects, which it is unnecessary for me to state at this time, as I shall have a better opportunity of pointing them out at large, should I be ordered to attend the Society. Instead of this uncertain way of constructing a balance, which never continues long in ie same state, but requires Objections. ” Cottman cue to the Society of grt! who voted a are of thirty guineas. to NEW BALANCE. 121 to be adjusted every time the watch wants cleaning ; I have rejected this mode altogether, and have contrived a method of applying the direct expansion of metals, which I find by experience to be constant and permanent in its effects. My balance consists of a flat steel bar, which forms its The new ba- diameter. Beneath this steel bar are two metallic rods, lang described secured at one end by a stud, formed out of the steel bar, ; and the other end acting on the short end of a lever, formed out of the other end of the same steel bar, being made to spring at the place where the centre of the lever would fall; to this lever is\fastened a small cylindrical ‘stem of brass, upon which a small globe of brass slides or screws ; there is also a screw passing through the stem, to Serve to regulate to mean time. Another metallic bar, equal and similar, and furnished like the other, but reversed in posi- tion, is placed parallel to it. Mode of acting. ‘When the whole balance is heated, the metallic rods will Action of the push forward the short ends of the levérs, and which mee eg, quantity will be just equal to the difference of the expansion ii of the two metals. Suppose the short ends of the two levers to be each equal to 1, and the long ends of the levers to be each equal to 20, then it is evident that the motion of each globe will be twenty times the excess of the steel bar and metallic rods nearer to the centre of the axis of the balance, than before the expansion took place ; and, what is a very grand and necessary property in the motion of the two globes, they will always move directly to the axis of the balance ; that is, their action will be constantly in a plane, passing through theaxis of the globes and axis of the balance, To increase or diminish the expansion of the balance, will be only to slide or screw up or down the globes upon . their stéms, until the balance produces the desiy ed effect, Additional Remarks on the Balance now in Use. The rim of brass and steel of the common balance, how- Manner in | » which th ever intimately. connected when first fluxed together, are by Ba nce: eh évery change of temperature endeavouring to break the pansion b3- connection, and do by little and little tear themselves det asunder, at least in a partial degree, for the fracture is VOL. KVL —f rs. 1807. M often 122. The new ba- Jance has no soldered or welded sur- face. Its weights NEW BALANCE. often visible, so that the balance has nothing permanent in its nature. New adjustment is necessary much oftener than the instrument requires cleaning: but that adjustment is of no duration; for, as the pores are more torn than at first, the balance becomes worse and worse, and at last quite useless for what it is intended. I make use of the direct expansion of metals; for the bars of my balance are independent of each other. They are connected only at the extremities, and the excess or difference of the expansion of the two metals is communi- cated to the short ends of the two spring levers. Its dura- bility can therefore no more be doubted than that of the gridiron pendulum, where the direct expansion of metals produces the desired effect. The two globular weights. were described in my last letter move nearlyin ag moving constantly in the. same plane, which passes a diameter. A noxious vi- bration of the weights in the common ba- lance. through their centres and the axis of the balance; and I should have added that, as to sense, they also move in the same right-line which passes through the centres of the globes, and cuts the axis of the balance at right angles; for the versed sine of a very small arch, or the difference be. tween the radius and co-sine, is in this case a quantity so small that it cannot be perceived ; and however we increase or diminish the expansion of the balance, or whatever may be the degree of temperature, it still retains this admirable property, namely, that the two spherical weights move not only in the same plane in a strict mathematical sense, but also in the same right line in a physical one, This quality, united with the direct motion of the brass bars, renders the motion of the globes simple and uniform, and therefore the effect (depending on such simple and direct causes) is regular and certain, The common balance, when in motion, causes the weights to fly off or recede from the axis of the balance, and this flying off will increase and diminish with the arch of vibra- tion in the balance: for, as there is nothing to brace the rim at the extremity of which the weight is suspended ; as the arch of vibration increases, the weight and rim are ‘thrown outward as much as the centrifugal force of the weight exceeds that of the elasticity of the rim, And as the arc of vibration diminishes, and consequently the . . centrifugal NEW BALANCE. centrifugal force, the weight is thrown inward by the elasticity of the rim. ) ; My weights or spheres are firmly braced in every degree of temperature, and consequently not influenced in the smallest degree by any change in their centrifugal forces ;. therefore, in every respect, this balance may be considered as permanent. 123 The great difficulty in constructing a balance, and in The new ba. applying the direct expansion of metals, is to contrive it so lance preserves as that it shall preserve its equilibrium in every degree of ptecqtnenee temperature, and-also admit of having all its parts made perfectly equal and similar by mechanical means. Both these important problems I have solved, by the introduction and application of a different principle from any yet used in the cqnstruction of the balance of a timekeeper; and I am fully satisfied, from a variety of experiments which Ihave made, that by this total change of system, I have made a higher step towards the perfection of time-keepers, than has been effected by any other means that haye come within my knowledge. eo Letter to the Secretary, by the Editor*. Dear Sir, - I take the liberty to express my opinion of the compen. sation-balance, which Mr. Hardy has submitted to the consideration of the Society of Arts. I think it a very excellent contrivance: the following are some of the reasons which, | presume, will entitle it to the approbation of that respectable Institution. 1st.—The invention of confining the flexure of the steel Advantages of bar to a small part near the end is new, and no less re- Mr. Hardy’ markable for its ingenuity and simplicity, than for the steady effect it produces. | . 2d.—The whole combination is particularly firm; and as the workmanship depends upon faces which are either * The useful and patriotic society to which this letter was addressed _ through their Secretary, is always ready to receive communications respecting the subjects proposed for their consideration; —N. | 124 NEW BALANCE. plain or turned in the lathe, it can very easily be manufac+ tured without requiring uncommon skill in the workman. ' 3d.—As it has neither working surfaces of contact, nor joints nor levers, it will regularly obey the minute changes of temperature, and will not act by jerks or starts. Explanation 4th.—In the expansion-bar consisting of two metals, of the mode of connected longitudinally by soldering or otherwise, the action in bars of brassand differences: of length between them, wien heated or cooled, steel'fused or are found to: produce .a bending of the whole bar, which : acy to- “is more the thinner its component. parts. . At the very surface of contact, and at a considerable distance on each side of that surface in thick bars, the principal effect must consist in what workmen would call wire-drawing the one metal, and upsetting the other. It is reasonable to think that this process must affect the properties of a balance so constructed, and cause it to deviate in the course of time from its original adjustment. This objection to the com- mon expansion-balance “appears to be ‘obviated in Mr. Hardy’s invention. The flexure of the brass takes place through its whole length, in a regular manner, and is in quantity but small; and the, flexure in the reduced parts of the steel bar will be equally slight, if the thickness of that part be made to bear the same proportion to its length. Hardy’s ba- Hence, and upon the whole, it may be concluded that when Jance has not once it is adjusted, it will not alter, and that in all changes the same faults of temperature it will be similarly affected, and will return to its original figure whenever the geek pe eae is restored. It is easily 5th.—Artists will probably consider it as a desirable — property ‘of the present instrument, that the adjustments for temperature being in lines aah parallel to the verge, will have no practical effect in deranging the adjustment for position. I have the honour to be, Dear Sir, Your most obedient ser vant, WILLIAM NICHOLSON. Soho-square, March 7th, 1805. To Cuarzes Taytor, Ese. quer A cer- NEW BALANCES): 125 A certificate, dated March 6th, 1805, was received from Mr. Alexander Cuming, of Pentonville, stating that he had seen Mr. Hardy’s expansion balance; that in his opinion it has considerable merit, and promises. te, aet wniigrisigy; steadily, and permanently. ~ Reference to the Engraving of Mr. William Hardy's Perma. nent Balance, Plate 1V. Fig. 4, 5 ; expressing in inches. and decimal parts of an inch, the dimensions ve the several _ pieces. ! Fig. 5. A A. Two slobes which slide on the eylindieal Figure and _ stems of two upright levers, and are fastened by screws, diagrains of by which the. effect. of the expansion‘ is inceance onithenew ba- diminished. | ‘tn CC. Two equal and similar screws, by. which the watch is adjusted. to mean time. D D. The verge. or axis of the balance. Ho EE. The combination of. the steel bar wil tlie. brass bars. ‘ Fig. 6.8 S. The steel bar, whose length iss.,.... 1.600 HES DRGAGER n.d» 20 ordi asld .asord equates 9 028m Te otRIGKNESS . oodh baw (aaanmbaun alk 0. Blogs BB, Two similar and equal brass bars, in length ACN gene eececes econce @eexeere ‘we eeerdeonecve 1,470 ' To breadth eaeht . dati. ee ececer ee eeweseees 0.078: An, thickness; GaGhy . 15/5 sisi» 5 sblitestace, O082 Length of the two springs formed out of. the: __ steel Bice) doh Uiee s abeicde « bey eanioid nevis evdla © Ath vc 0:030. 126 The relative velocity of machinery connected by band is not variable, Invention of the author to make it so. IMPROVED WHEEL. VIII. ‘Description of an expanding Band Wheel to regulate thé Velocity of Machinery. By Mr. ‘imp Fi LINT*, In the usual method of Jiuatechihe machinery, by a band, running over two wheels or riggers ; it is obvious that the relative velocity of the wheels is in the inverse ratio of their diameters ; and these diameters always remaining the same, no alteration of the velocity can be obtained, but by a corresponding variation in that of the moving power applied. To enable the artizan to regulate the velocity of his machinery at pleasure, the moving power remaining as before, or to retain the same motion, with an alteration in that of the applied force, is the purpose of the invention, the models of which are now laid before the Society. In this model are shewn two methods of attaining this desirable object ; in both, the periphery of the band-wheel is divided into any convenient number of parts, according to the size of the wheels, (in this case twelve) which may be placed at any given distance from the centre of the wheel, (within the limits of the machinery) and thus, by enlarging the circumference of one band-wheel, while the other is equally diminished, to alter the relative velocity of each at will.” These parts of the periphery, which 4 term V’s, and are to move in grooves, cut in the large wheels A and B, Fig, J. and II. in the direction of their radii, and are weaved by a spiral thread in the small wheel C, which thread takes in the teeth of the racks on which the V’s are fixed. A part of the shaft on which the wheel A is fixed, is made circular, to admit the small wheel C to turn round inde- pendently of the other, and thus to extend or contract the racks and V’s in Fig. I1].—Fig. IV. is a section of part of the rigger, in which the letters refer to the same parts as in » Fig. I. and II. * Society of Arts, Vol. XXIII. A premium of fifty guineas was awarded for this invention. ; n NATIVE MINIUM. 197 In the wheel D, the same effect is produced by the screws, €, ¢, &c. which are made alternately right and left handed, and turn with equal motions, by means of the equal bevil-wheels f, f, &c.-fixed at their ends near the axis of the ‘wheel. Fig. V. is a section of the same. The wheel C, Fig. I. and II. is moved round the shaft d by the pinion g, on the axis of which is fitted occasionally a winch. The screws of the wheel D, Fig. III. may be also turned, by means of a winch applied to their projecting heads h,h, h. It is proper to notice that the number of the screws must always be equal. ANDREW FLint. Goswell Street, London. IX. — Account of a Discovery of native Minium. In a Letter from James Smrtuson, Esq. F.R.S. to the Right Hon. Sir Josreu Banks, K.B. P.R.S.* MY DEAR SIR, I BEG leave to acquaint you with a discovery which I Character and have lately made, as it adds a new, and perhaps it may be habitudes of thought an interesting, species to the ores of lead, I have tive minium found mtnium native in the earth. It is disseminated in small quantity, in the substance of a _ compact carbonate of zinc, _ Its appearance in general is that of a matter ina pulveru- Jent state, but in places it shows to a lensa flaky and crys- talline texture. Its colour is like that of factitious minium, a vivid red with a cast of yellow. Gently heated at the blowpipe it assumes a darker colour, but on cooling it returns to its originalred. At a stronger heat it meltg to litharge, On the charcoal it reduces to lead, * Philosophical Transactions for 1806. : In 12p It seems to be produced by decay of ga- lena. The natural history of me- nacane has been little at- tended to. “Cassellin Hesse, MENACANE, AND ITS ORES. — In dilute white acid of nitre, it becomes of a coffee colour. On the addition of a little sugar, this brown calx dissolves, and produces a colourless solution. By putting it into marineacide with a little leaf gold, the gold is soon entirely dissolved. When it is inclosed in a small bottle with marine acid, and alittle bit of paper tinged by turnsol is fixed to the cork, the paper in a short time entirely loses its blue colour, mr be- comes white. A strip of common blue paper, whose colour- ing matter is indigo, placed in the same situation undergoes the same change. The very smal] quantity which I possess of this ore, and the manner in which it is scattered amongst another sub- stance, and blended with it, have not allowed of more quali- ties being determined, but I apprehend these to be sufficient to éstablish its mente This nativé minium seems to be produced by the decay of a galena, which I suspect to be itself a secondary produc- tion from the metallization of white carbonate of lead by hepatic gas... This is particularly evident in a specimen of this ore which I mean to send, to Mr. Grey ille, as soon as I can find anopportunity. In one part of it there is a cluster of large crystals. Having broken one of these, it proved to be converted into minium to a considerable thickness, whileits centre is still galena. Mio ee Tam, &c, JAMES SMITHSON. March 2d, 1806. An Account of « new semi-metallic Substance, called Mena- cane, andits Ores. By the late G. Mrrener; M.B.* Styce the discovery of Menacane, by Mr. Gregor, the distinguishing properties of the peculiar metallic substance it 5.0% drish, Transactions, Vol. x, are contains MENACANE, AND ITS ORES. contains have been so fully developed, and ‘satisfactorily: ascertained, by the united exertions of Kirwan, Klaproth, Vauquelin, and Lampadius, that little is left to wish for, so far as the chemical characters are concerned. As an object of natural history, it has, as yet, been little attended to., It is therefore hoped, the following attempt, to supply in some, measure that deficiency, so far as the present data allow it, will proveacceptable to the naturalist. Itis scarcely neces- sary to observe, that I follow Werner’s method most ex- actly: asit is to him that we are indebted for the successful vindication of Mineralogy, as an independent province in: the feederal state of natural history; and which acknows: ledges, in Chemistry, the powerful and indispensable ally, not the imperious and arbitrary law-giver. 129 Of the genus Menac we are already acquainted with five Five species. species or ores. It is, however sufficiently probable, that several new species will, at no distant period, be added to the list; and that this metal is more widely distributed, and more generally diffused, and plays, perhaps, a more impor- tant part, than is at present suspected. MENAC, GENUS. es : 1. Rutile. Tribe of Rutile.... 2, Rutilite. 3. Nigrine. Tribe of Menacane..4 4. Menacane, ‘ 5. Iserine, pee FIRST SPECIES. RUTILE*. Titantte of Kirwan. Rutil of Werner. Sagenite of Saussure, EXTERNAL CHARACTERS. Species I, Rutile. _ The colour varies from light hyacinth to dark brownish External chas. red. Is found crystallized. 1. In right angled four-sided * Probably the anatase of Hauy is a variety of Rutile —R. J. Vor, XVI.—Fexz. 1807. N prisms, racters, 130 Observations on Rutile. MENACANE, AND ITS ORES. prisms, acnminated by four planes, which are set on the Jateral.planes. 2. Insix-sided prisms, which are said some- times to exhibit a tendency to a six-sided acumination. 3. Tn acicular and capilliform crystals, whose regular shape is no longer determinable, and which are, moreover, shila sep compressed. The crystals are longitudinally sulcated, often very deeply; are commonly small, and very small, rarely middle sized. The acicular are often fascicularly aggregated: the capilli- form crystals are often in a singular manner reticulated, the interstices forming equilateral triangles ; exteriorly, shining and moderately aaa 5 interiorly, glistening ; the lustre adamantine. The principal fr ached is foliated with a two-fold cleavage, cutting each other at right angles: the transverse fracture is imperfect and minute conchoidal. The fragments are cu- bical. It sometimes exhibits slender, columnar, distinct concretions. Is usually translucent, sometimes only trans- lucent at the edges. Hard. Brittle. Gives a pale orange yellow streak. Js easily frangible. Heavy, in an. inferior degree, about 4,200. ] _ OBSERVATIONS. The larger crystals, particularly those from Hungary, are often curved, have frequent transverse rifts, are sometimes broken entirely across, the ends removed to some distance from one another, and the interstices filled up with the sub- stance of which the matrix consists: sometimes two crystals meet under an angle more or less obtuse, and are joined like the corner of a frame. The crystals are, morcover subject to great irregularities, arc seldom fully crystallized, and, therefore, rarely acuminated ; the four-sided prisms are often slightly rhomhoidal ; the six-sided prisms, from Hungary, are usually dilated, and-seem coraposed of accumulated acicular crystals, from whence arise the columnar distinct concre- tions ; the six-sided prisms, from France, are said to origi- nate from the truncation of two opposite lateral edges of the four-sided prism; the capilliform crystals are sometimes coloured green, from chlorite earth. By some authors, this fossil has becn said to resemble red silver ore; but the slightest acquaintance with the oryctognostical Shabicters is sufficient to shew the difference ; a geognostical character also furnishes ‘ MENACANE, AND ITS ORES. EST furnishes us here with an easy means of distinguishing this fossil from other ores of a red colour. Rutile is generally’ of cotemporaneous formation with its associated fossils';’ whereas red silver ore, red orpiment, &c. being formed in veins, are always of later formation than the rock on which they are seated. Some systematic writers have confounded it with rubellite, with which it has scarcely two Cmaneaneres in common. CHEMICAL CHARACTERS. 7) 7" | Without addition, or even with phosphoric salts, it is in- ree erage che fusible by the heat of the common blow-pipe ; with borax or rutile. alkali, it affords a hyacinth red transparent glass ; with | the heat excited by pure air, it gives a milk white bead, and suffers a considerable loss of weight. It isinsoluble in the mineral acids, before it has been melted with alkali, but yields readily to acid: of sugar; is precipitable by acid of galls witha bright red, and by Prussian alkali with an hand~ some dark green colour. ‘The method of analysis I shall omit, as belonging properly to mineralogical chemistry ; the result has shewn that this fossil consists wholly of the calx of Menac. GEOGRAPHIC DISTRIBUTION. 1 This fossil has hitherto been discovered in but few places, Geographic distribution: of and in moderate quantity, principally near Rosenau, IN rytile. Upper Hungary; in Mount St. Gothard, in Switzerland; in Fischthal, inthe high mountains of Saltzburg; ‘near St. Yrieux, in France; in the province of Burgos, in Spain; in the forest of Speysart, near Aschaffenberg, in Franconia; at Beresooskoi, in Siberia; and Olapian, in Transylvania, GEOGNOSTIC OCCURRENCE. The Hungarian rutile is found imbedded in a kind of Geognostic quartz, passing into rock crystal, and forming nests in mica occurrence of slate; it is therefore of cotemporaneous formation with the Riggs rock in which itlies. That from St. Gothard, in Switzer- land, occurs partiy in those drusy cavities, which are not unfrequent in granific mountains of high antiquity, lying in or upon the rock crystal, adularia, and foliated chlorite, with _ which those cavities are lined, and partly dispersed through, fits N2 or 132 Species Ih Rutilite. External cha- racters, + : MENAOANE, “AND ITS OREs. or. Seated‘in, the scarcely: perceptible clefts of one of those nameless chloritic rocks, which abound so much throughout the Alps jin general. That. from Aschaffenberg is said to occur in granite; that from Saltzburg is found imbedded in massive common tremolite. The asi from Spain and Si- beria is embedded in rock crystal. It would therefore ap- pear, that this fossil lays claim to great-antiquity, the time of its production falling within the period of the earlier primi- tive rocks, and that the metal it contains probably surpasses, in that respect, tin, molybdena, and mpseteD, Vieing even with iron and manganese *, The above description has been chiefly neha from. an ‘attentive examination of the specimens of rutile existing in the best collections of Vienna and Saxony, Pas ar : ‘SECOND SPECIES. an | RUTILITE. “Calear reo-siliceous titan ore of Kirwan, Titanit of Klaproth. EXTERNAL CHARACTERS. The colour varies from brownish ed to dark reddish brown. Has been hitherto found only crystallized in very rhomboidal four-sided prisms, acutely bevelled at the extre- mities, the bevelling planes set on the obtuse lateral edges. The crystals are small, and very small, seldom middle sized. Exteriorly, they are mee ear. glistening, with a resinous lustre. The fracture is imperfect and minute con- * Von Buch has discovered rutile in layers of quartz, in clay slate (Thonschiefer), near Nihlbach, in Saltzburg, in the vicinity of metal- lic layers, consisting of copper glance, copper pyrites, iron pyrites, nickel, and rarely native copper: alsoon the mountain Brennkogl, in the valley of Fusch; where it occurs in mica slate, either reticularly aggregated in rifts, orin acicular crystals, accompanied by those singu- lar cylindrically aggregated crystals of foliated chlorite, in venules of almost coeval formation with the rock itself—Buch’s Geognostiche Beobachtungens—R. J. - Rutile has also been discovered by Von Humboldt, on the summit of a mountain near Caraccia, in’ New Granada, at the height of 1316 toises.—R. J. 5 choidal, MENACANE, AND ITS ORES. choidal, passing into the uncyen. The fragments, are inde- fexmainatély angular, tolerably sharp edged. The transpa- rency varies, from translucent, through translucent. at the edges, to opaque. Is semi-hard, bordering upon hard. Brittle. Gives a greyish white streak. _ Is easily: frangible. Not cecal hers > appncaching the heavy (3,500). 1s a OBSERV. ATION s. The lateral planes meet alternately under angles of 135° and 45. From the foregoing fossil it is sufficiently distin- guished by crystallization, fracture, inferior hardness, and specific gravity. From grenatite it may readily be discrimi nated, by the difference in crystallization, Pectare, and sort of lustre. a CHEMICAL CHARACTERS. Before the blow-pipe it suffers no change, nor in the heat ofa porcelain furnace, when exposed in an earthen cru- cible; but in a crucible of. charcoal it melts to an imperfect black glass, owing to the partial reduction -of the metallic contents. -With considerable difficulty, and only by re- peated digestion, marine acid dissolves a third part of the weight of this fossil, consisting partly of the menac contents. Klaproth, from itd these’ characters are taken, found it to consist of nearly equal. parts menac-calx, silex, and lime, to which Vauquelin joins a large portion of iron calx. GEOGNOSTIC OCCURRENCE. 133 Observations on rutile. Chemical chas racters. In the mountains of Passau, this fossil is found imbedded Geognostic in a coarse granular aggregate of felspar and hornblende, and occurrence of felspar and actynolite; therefore belonging to the’ genus green~ ~stone, and order of primitive trap. In Norway it Oc- curs in rocks belonging to the same formation, in which the celebrated layers of magnetic iron ore lic, and is associated with hornblende, and several individuals ofa tribe not as yet sufficiently examined and described, -but which evidently constitute middle links between Abtadtive and hornblende, and to which the names arendalite and acanticone have been applied. Near Dresden and Bri linn it is found dispersed through sicnite; and at Galway, in Ireland, in an Bacom. monly beautiful porphyritic sienite. _ Hence it appears, that this rutilite. 134 Species III. Nigrine. External cha- racters. Observations on nigrine, MENACANE, AND ITS ORES. this fossil has only occurred:in rocks belonging to primitive trap, or in sienite, the last crystallization which took place within the primitive period, and must therefore be-considered as a later production than rutile. Here a consideration of the laws of crystallization countenances the observations on the order in which the primitive rocks follow one another. The rutile, consisting of few and simple elements of cotem- porary origin, with a granite, in which rock crystal occupies the place of quartz, and adularia that of common felspar, sufficiently bespeaks a period, when the solution being purer and more tranquil, furnished an earlier and purer crop of erystals; while the confused and irregular crystallization of primitive trap and sienite, together with the greater impurity of the felspar, and very compounded nature of the horn- blende and rutilite, indicate an inferior purity of the solu- tion, and, consequently, later precipitation of the crystallized mass, THIRD SPECIES. NIGRINE. Nigrin of Werner. EXTERNAL CHARACTERS. The colour is dark brownish black, passing into velvet black. Is found in larger and smaller angular grains, and pebbles. Externally, moderately. glistening. Internally, principal fracture is glistening ; the transverse fracture mo~ derately glistening. Lustre, adamantine. The principal fracture is imperfectly foliated, with a single cleavage; the transyerse fracture is flat, and imperfectly conchoidal. The fragments are indeterminately angular, and sharp-edged. Perfectly opaque. Semihard. Brittle. Gives a yellowish brown streak. Heavy, ina moderate degree (4,500). OBSERVATIONS. This fossil is readily distinguished from menacane, by its stronger lustre and superior hardness, the colour of the streak, and by its not being in the least magnetic; which alse MENACANE, AND ITS ORES. also sufficiently distinguishes it from iserine and iron sand *. Being found in company with fragments of rutile of a dark colour, the latter has by most been confounded under the same denomination ; but the red colour of the rutile, joined to its perfectly foliated fracture, with a two-fold cleavage, intersecting each other at right angles, and the thence re. sulting cubical fragments, distinguish it sufficiently from “nigrine. , . The present description is taken from a specimen I had 135 the pleasure of receiving from Professor Jacquine the younger, of Vienna, CHEMICAL CHARACTERS. The nigrine is infusible per se by the blow-pipe: but, with the assistance of borax, it melts to a transparent, hyacinth red bead: to acid of sugar, it readily yields its medac con- tents, which furnishes the characteristic precipitate of this genus. Klaproth and Lampadius have given us the consti« tuent ingredients, 8 or 9 per cent. menac calx, and 2 or 1 calx ofiron. It is probable, however, that the proportion of menac calx is over-rated ; it appearing evident, from the description accompanying the analysis, that there had been no care taken to select the nigrine from the grains of rutile . which accompany it. GEOGNOSTIC OCCURRENCE. _ The nigrine has been hitherto found only at Ohlapian, in Transylvania, in alluvial hills, consisting of yellow sand, in- termixed with fragments and bowlders of granite, gneiss, and mica slate, and from which gold is obtained by washing. This gold is the purest found in Transylvania; a circum- stance sufficiently indicating, that it belongs to a different, and, consequently, earlier formation, than the usual Tran- sylvanian native gold, which occurs there in clay por. Chemical cha- racters of nigrine. Geognostic oc- currence of nigrine. phyry, grey wacce, and grey wacce slate, and belongs to the © brass yellow variety, from the considerable alloy of silver which it contains. In these stream works, the nigrine is * Genuine iron sand must not be confounded with magnetic iron ore in a sandy form, which usually passes under that name. obtained 136 Species 1V. Menacane. External cha- racters. Observations on menacane, Physical and chemical cha- acters. i MENACANE, AND ITS ORES. obtained at the same time with the gold, and comes to us intermixed with grains of rutile, oriental garnet, native iron, cyanite, and common sand; which ‘renders it extremely probable, that this fossil, alsoy/i is a smeye of the primitive TARR EARNS. FOURTH SPECIES. MENACANE, Menachanile of Kirwan. Menacan of Werner. EXTERNAL CHARACTERS. Is of a greyish colour, inclining somewhat to iron black. Only met with in very small flattish, angular grains, which haye a rough glimmering ae. ei moderately glistening, with adamantine lustre, passing into the semi- metallic. The fracture is perfectly foliated, approaching to the slaty. The fragments are indeterminately angular, and sharp-edged. Perfectly opaque. Issoft. Brittle. Retains its colour in. the streak. Lasily frangible. Heavy, in a moderate degree (4,427). | OBSERVATIONS. This fossil has been said, but erroneously, to have much resemblance to iron sand, from which it may be easily distinguished by the fracture, lustre, and inferior specific gravity, PHYSICAL AND CHEMICAL CHARACTERS. Menacane is attractable by the magnet, but much more weakly than iron sand, or magnetical iron ore; it is infu-. sible by the common blow-pipe, or heat of a porcelain furnace, exposed in a coal crucible, but melts, when in contact with a clay one; it also melts quickly to a black bead, before a blow-pipe animated by pure air. The menac contents may be easily extracted by digestion with acid of sugar. Klaproth and Lampadius, about the same time, have shewn, that it consists of nearly equal parts menac and iron calces. GEO. MENACANE, AND. 1TS, ORES, Oem ae >) rang GEOGNOSTIC OCCURRENCE. 1 This fossil has hitherto been only found, accompanied Geognostic os by fine quartz sand, in the bed of a rivulet, which washes Occurrences” the valley of iMenuchari; in Cornwall. The neighbouring mountains ‘belong to the primitive order, in which, most probably; the menacane formerly constituted a superficial layer ; but, by their decomposition, and consequent degra- dation, by means of rains and floods, the earthy parts have been carried off, and the heavier metallic fragments collected ~ in the valley. ! \ aso FIFTH SPECIES. _ Species V. Iserine: ISERINE. [seri ine sg ib ini EXTERNAL CHARACTERS, ! The colour is iron black, inclining a little to brownish External chae black. Is found in small obtuse, angular grains, and in T*ter® pebbles, with a somewhat rough, strongly glimmering surface. Internally, it is shining, with semi-metallic lustre. Frac- ture is more or less perfectly conchoidal. Fragments are indefinitely angular, and sharp-edged. Perfectly opaque. Hard. Brittle. Retains its colourin the streak. Is heavy, in a moderate degree (4,500). OBSERVATIONS. ’ Of all fossils, this has the strongest resemblance to iron Ghvcrendidee sand ; into which, as Mr. Werner first observed, it actually on Iserine. graduates, but may be distinguished from it by the shade of brown in its colour; by its superior external, and in. fevior internal lustre; by its less specific gravity ; but, chiefly, by being only slightly, and that by a paeverfal magnet, attractable. From nigrine and menacane, it differs sufficiently in fracture and lustre. ‘This, as well as nigrine, was first considered as a particular species by Werner: both which determinations were afterwards confirmed by the ana- lysis. “Vor. XVI.—F ex. 1807. O CHEMICAL e 138 Chemical chase ; rac terse Geognostic eccurrence of Iserine, General re- marks en me~. MENACANE, AND ITS’ ORES. CHEMICAL CHARACTERS. Asin the foregoing species, the menac calx may here be ~~’ readily extracted by, ;acid jof sugar, the residuum. being dis- solved in aqua.regia: on, the addition of tartarised tartari in, 2 lemon yellow, powder fallsto the bottom, which is tartarised menac; whatremains in the solution is iron... Lampadius, to. whom we.owe, the analysis, found, that menac and iron are here in a decreasing proportion; the latter amounting to about 20 per cent, A late experiment has shewn him, that iron sand contains the same principles, but, probably, in an inverted proportion. GEOGNOSTIC OCCURRENCE. Hitherto this fossil has been only found in the high Riesen mountains, which separate Silesia from Bohemia, near the origin of the Iser, dispersed through the granitic sand which forms the bed of that river. To what order of rocks it owes its origin is uncertain; but its near affinity to iron sand, which is exclusively an inmate of the fldiz trap forma- fon and the certainty, that this formation was formerly superstratified, at a great elevation, on the Riesen mountains, (as the es which form the Buchberg*, and occupy the Schneegruben, sufficiently testify,) render it highly probable, that this fossil, also, may belong to that forma- tion; and, consequently, dates its origin froma much more recent period than the foregoing species of this genus t. GENERAL REMARKS. These are the only fossils of this genus, with whose cha- * The Buchbeie (which I eniporedl the invaluable opportunity, of examining with my excellent and ever to be regretted friend) is the ~ highest basalt hillin Germany, being 2921 fect above the level of the sea, and the ‘highest basalt, except that small quantity lodged in the ¢avity of the Schneegruben, which issome hundred fect higher. ‘Lhe hillitself is elevated about 500 feet above the Iser, that washes its gra- nitic basis, and the Iserine is found at some distance below. We could, indeed, discover no trace of it in the basalt of the present hill —R. J. “+ Mr. Gregor (as stated in Nicholson’s Journal) has found, that me- nac is one of the constituent ingredients of basalt; a fact, which’ adds much to the plausibility of Dr. Mitchell’s very ingenious supposition, -—R. J. Tracters MENACANE,, AND ITS ORES. 139 yacters we are as yet sufficiently, acquainted -to. say,.‘with nacane and its certainty, that. they form. distinct species... Between, the’ three latter and iron sand, the intermediate transitions, as between all: adjacent, fossils, are, probably, innumerable, Were we to take analysis alone for, our.guide, it would sy tiply- the species without necessity, and lose. sight, of, the ins tentions of Nature, who does not confine herself to 5 or 10 per cent. of an ingrédient; beside, a Klaproth has confessed, that it is not so much the identity and. proportion: of ‘the in- gredients, as the particular state, of their combination, (which to usis perfectly unknown,) that determines thé na. ture of the resulting fossil., In addition to those ‘fully de. termined species, we have been favoured, by Klaproth, with the analysis of a menacaniferous ore, from Aschaffenberg’; by Vauquelin, with that of another, from: Bavaria; and, by Abildgaard, with that of a third, from Barboe,in N orway’; all which differ from the foregoing species, and from one another, in composition, or in the proportion of ingredients; so that it is impossible to determine, with any probability, to what species they belong, from the want of an adequate ores. external description, and account of their geognostic oc. currence. The masterly hand of Klaproth has further detected this metal, in the iron sand, which accompanies the hyacynths, &c. in Ceylon, and in some of the iron ores of Norway; and Lampadius has lately discovered it, in theiron sand of Hohenstein, near Stolpen, in Saxony, and in that found with the pyrope of Bohemia. Besides these, I have seen, in the imperial cabinet, at Vienna, and some few private col- lections, ores, said to come from Stiria or Carinthia, and from Bohemia, in which the menace calx probably abounded; as may be conjectured, from the strong shade of brown in the colour, together with the considerable adamantine lustre, _both which are strongly characteristic of this genus, _ The use of this metal is, as will readily be supposed, from its scarcity, and the newness of its discovery, very confined. The rutile, indeed, was, for a length of time, employed to give a brown colour, in the porcelain manufacture of Se. vres, near Paris; but, from the difficulty of communicating an equal tint by it, has been since abandoned, The. rock -erystal, inclosing capilliform crystals of rutile, has becn 02 employed Uses. 140 Useful instruc- tions for de- fending grapes, and giving them the ad- ‘vantages of sunshine, and the heat of a wall, &ce. GRAPES. employed asa setting forrings. The precipitates, especially those from acid of sugar, may be employed as water colours; that, by acid of galls, affording 2 good tile red, and that, with Prussian alkali, an agreeable dark ‘green. The latter, also, communicates a durable colour to silk, as.my friend, Lampadius, assures me; perhaps, with proper management, it might be employed to furnish the so much wished for dura- ble green for the printing of cotton. Arid, lastly,. its close connection with some iron ores, and those exactiy of the most superior quality, such as the ores of Norway and Stiria, Jeads naturally to the suspicion, that it may possess some favourable influence upon the manufacture of iron, and, therefore, well deserves the attention of future inquirers.- Such are the principal circumstances, at present known, ‘respecting this genus of fossils; time will, doubtless, here, as usual, find much to amend, to correct, and to supply. XI. On the Cultivation of Grapes. By Gro. CumBerianp, Esq. To Mr. Nicuonson. Sir, Bristol, Jan. 18, 1807. Porcervus G that practicable improvements in all the arts that benefit existence are sure to mect with a favour- able reception in your Journal, IT trust you will accept the following account of some pra ttiBe’ that have lately been successful in the management of fruit trees, ogee the- vine on the exposed wall. Having last year come into possession of some south walls covered with vines that were said not always to ripen so well as might be expected, I was advised to cover them with glass, as the only sure means of securing a very considerable pro- duce; but as that mode was too expensive to suit my cir. cumstances, I resolved to make trial of less costly expe- dients, and at first turned my thoughts to those bell-glasses “blown with a hole in the back, into which the young bunches are introduced very early so as to expand within the glass, and when ripe are severed at the stalk, and delivered at the wider aperture. The . GRAPES. 1Al The objection to these, however, soon appeared to be, Useful instruc» that, even at the glass-houses costing 2s. 6d. each, and up- tions for de- : : ° fending grapes; wards, it required at least five years to recover their cost, 214 giving according to the value of the fruit; next, that in consequence them the ad- of the hole madein the back they are uncommonly brittle; Prva ie, $e a then, that they can only be applied at a very early season 3; the heat of a and lastly, that. their colour being obscure, they were on Wall, &c. that account less likely to advance the maturity of the bunches (one only of which can be introduced to each) than » materials more diaphanous. Finding therefore that to blow them of white: glass would nearly double their price, I _ caused some white flasks of the best flint glass, of about one foot long, to be divided in two by means of the process with a hot coal, and thus J procured out of each flask two covers of the shape-of half melons, each of which were capable of covering two bunches at least; of smal] ones three at a time 3 and buying them by weight, I found they stood me in only about one shilling each. These segments 1 bound with packthread, by making a sling and atie, so that they were easily attached to the wall by means ef a nail, and kept from swinging by a. cross thread or two, and thus I covered a great many bunches at all periods, commencing with them when about four or five inches long, and stopping the east side of the glasses with the fresh leaves as I picked them off; for, contrary to the usual practice, ] exposed my bunches while green to the sun par. tially, and some entirely, at a very early period; at a very early period also I began to strip all the leaves from the - wall, and.to take away all extraneous growth: in fact, I suffered no leaf to remain that touched the wall from the time the vines first came into leaf until the period when the grapes were almost ripe, nor any bunch of grapes at any period to be totally excluded from the sun, laying them par- ticularly open to his declining beams, and only securing them with what care I could from the too piercing rays of noon. . ; In this manner, under these clear glasses, I exposed several “bunches of a sweetwater, growing on a buttress in an angle _of about 80 deg. duesouth, to every ray of sunshine, except _ the direct ones, and not only did so, but I cleared every leaf -away from the wall that approached within a foot each way of 142 GRAPES. Usefulinstrues Of the bunch covered with: glass; and thus ‘I ripened fully tions for de- several bunches as early as the middle of July, some even Se ee earlier, without any symptoms of scorching: taking care to them the ad-) leta a6 proportion of air: flow under the glasses, yet not so vantages Of little as 1 allowed to Jater fruit; by which management I sunshine the heat of a) Was enabled to eat, from walls of ihe same aspect, ripe grapes wall, &e. —* all last summer, ni? from J aly” to November, whilst many of my neighbours did not ripen any before the end of August or middle of September, and many others, from the old pre- judice that grapes ripen best in the shade, neglected to re- move the leayesaintil they lost the whoie crop. Another plan that I adopted, and which was most essen tially useful, was carefully to nail down every branch to the wall, so as ty make it come-in close contact, as soon as they were of a size to make that operation possible-—And lastly, as soon as the bunches were ripe on the outer side, I had every one turned with the unripe side to the sun; to-some even we gave a second turning, (an operation very easily - performed with the hand when thus nailed close, ) so that out of many hundred bunches of grapes of different»sorts, among which was even the Gibraltar, I not only ripened completely every bunch, but I may with truth say nearly every grape on my wall, the greater part without glasses, after a certain period, but they: were all forwarded by these glasses, removing them from one place to another as I gathered what they had completely matured. - Lalso found very useful at the latter end: of the season, those small conical hand caps; which are made for about eighteen pence a piece, by running a rope with a tye from the finger hole at the point along the inner side, and: there suspending them by a loop of cord. to a nail onthe wall’; by which means they hang perpendicular with the wall’s face, and are capable of covering and protecting from sluggs five or six bunches at once, brought together by altering the nailing. But this contrivance, which unites ceconomy with utility, (for at this season they are qut of use for any ‘other purpose, ) should only be applied when: the: grapes are advancing fast to maturity ; as I have. found by experience that the colour of the glass being green does not much advance their ripening, and that at the very latter part of the season it rather, retards it.—For all my trials | have taught GRAPES.’ 143 taught me, that in proportion as ‘the glass is white and yserurinstrucs transparent, nay even carefully cleaned, the grapes are bene- tions for de- fending grapes, fited ; and that next to the taking away thie Yeaves from the |~ d Wivine walls which if left would prevent them fromm betting properly them the ad-~ heated in the day time, the nailing: t the bunches themselves hha so “a a close to the wall is advantageous in the highest degree. ~~ the heat of 2 ‘Many of'your readers (for I know on this business how wall, &c. much we have to contend with prejudice,) will think that my Situation must have been remarkably suitable to the ripening of grapes, but I’ can assure them that it is not exactly the case, as my walls are almost within the city, much ‘cut by the east wind, and have but little afternoon sun 3 but what will best satisfy then will: be the confession that I could scarce at: all ripen any on my Pergola or _ Espalier frames, and that even: flasks: would: not ta well some in that situation. It is a serious thing to advise new twandelnont to old practitioners, but 1 can assure you that the success of this conduct, practised in the very teeth of their reprobation, was so complete, that I»could have made wine of all my grapes, and that I actually dried some under these clear glasses nearly to raisins.—When all were full ripe I bagged in paper the remainder, and on’ Christmas day, 1 eat my last bunches. preserved ‘by hanging them near the kitchen fire in the, bags I cut them, off in; while on the vines, in * October, two bunches remained quite unripe that I pure ‘posely left at only two. inches ‘distant from the warmest ‘ part of the wall sheltered ‘by leaves. What led me to this system of extreme exposure to light and heat, was the obsers vation, that I have often made both no the Rhine and in the neighbourhood of the Sabine Hills, that those who would have earlyograpes must even there give them® plenty ‘of suns shine: and on the Rhine-we:know that land‘for vineyards is exactly valued in the proportion in which it receives the sun, a mode of valuing land that in many‘cases] think will one day prevail every where, particularly on the sides of our poorer hills; “for near Hochheim and the vineyards of Riefenstien, the highest and the lowest ‘tented lands ‘are often on the same hill, while here they seck the northern aspect.to grow corn, forgetting the ‘earlier products: which the south can afford to the hand of industry, or rather having 144 Useful instruc- tions for de- fending grapes, and giving them the ad- vantagcs of sunshine an the heat of a wall, &e, 5 Great advan- tages of wool as a defence for peaches, &c GRAPES. having nothing more profitable to grow in their estimation ; for it is only a very few years since, the walls and some of the vines now remaining, that a Mr. Fry had at Axbridge a well bearing vineyard on the southern side of that ro- mantic hill, on land not.worth at any rate more than half a crown an acre; and I have known a sack of very early potatoes sold for eighteen shillings, that were in a similar situation raised in the natural bed on Jand of no greater value; and filberts it is well known-will grow on most of our southern poor hill lands, almost without the hand of culture. ‘ Thus much I have thought might be useful to many,people to know who have vines, which, for want of understanding these methods, they suffer either to remain as unfruitful or- naments, or coolly contemplate the destruction of, scarcely ever affording them the least manure, and expecting a spon~- taneous product once in six or seven years without any care atall. For although we have many expensive treatises on the management of vines under glass, except Evelyn in his ‘French Gardener,’ we have few authors who shew the possi- bility of raising a good English vineyard fit to make wine from; and as nothing is so easy as to make good wine from quite ripe grapes, I trust, by facilitating that operation, I shall render some useful service to the British wine grower, and, at any rate, increase the value of many vine-covered walls. G10 And now, Sir, having taken up, I fear, but toe much of your paper, I will only. beg leave to add, as briefly as pos- sible, that last year, for the first time, I used coarse wool, in the roughstate, to. scréen my peach and apricot blossoms from the east winds, by tucking it into the east side of every bunch of bloom, instead of fern, laurel leaves, or broom ; and that this afforded an effectual security to the fruit even after it wasset; an improvement which has these advantages, that itis always at hand, is cheap, can be repeatedly used, gives no strokes to the wallin windy weather, and keeps up an eyen temperature in the night, while it makes less litter, gives less shade, and by being left on, encourages the growth of the fruit, by retaining the dews and securing the fruit stalk from the scorching reflection of the wall at noon. : Trusting ORKNEY AND SHETLAND ISLES. 14 "Trusting that its utility may prove an apology for the haste. with which the paper is written, ~ T remain, Sir, Always your obliged humble servant, G. CUMBERLAND. Useful Notes and Observations recpecting the Islands of Orkney and Shetland. By Parnicx Neri, A.M. Secre- tary to the Natural History Society of Edinburgh.* Ti circumstance of the shores of Norway being clothed Eo with fir-trees+, is doubtless.a strong analogical argument iD trees. : The favour of the practicability of raising timber in the Orkney Orkneys, &c. and Shetland islands. ansibees ' €¢ In respect to. the soil,” wie the Bishop of Bergent), *¢ it is not the good, rich and black carth, ‘* that favours ‘¢ the fir-trees ; nor the clayey soil; but rather the gravelly, sandy, or moorish Jands.” This is an observation well calculated to inspire hopes of success. ‘Thousands of young fir-plants are cut, every spring, by Whether the peasants of Norway, for. food to their cattle. It would agosto not probably be difficult, therefore, to procure quantities Norway. of saplings from that etuwiee. But if this were found to be too troublesome, it may be sugzested that the ripe cones might he brought over (and these could easily be collected), and that the seeds might, by way of trial, be sewn where the trees were intended to grow. This tale plan might * Extracted by permission from his “ Tour through some of the Islands of Orkney and Shetland.” The spirit of active industry and the consequent improvements in scicnce, arts and manufactures in eVery part of our island, cannot be better shewn and promoted than by the travels of intelligent observers. Most of the subjects in the small book before us are of great national importance and interest, particularly at a moment when so many of our sources of prosperity are endangered.—N. + The fir trees of Norway are, I find, the Lure, or spruce, pimus abies (not the silver fir); and the gran, or pine, pinus sylvestris, well known by thename of Scots fir. 2 ¢ Nat. Hist.of Norway, Vol. I. p. 143. Vor. XVI.—Fes. 1807. © P possibly 146 i Remarkable fact that trees seem to prefer the west coasts. \ ORKNEY AND SHETLAND ISLES. possibly be found preferable to raising the plants in nurseries or gardens in the islands. We should, in such cases, adopt every approximation to the methods of nature. Pontopid- dan even suggests, that. instead of inserting the seeds in the soil, it would be better to hang the branches, containing the cones, upon poles at different distances, and to allow the seeds to drop out and sow themselves. At any rate, the seeds might be merely raked in. ‘The experiment might be tried on any piece of dry rocky land (an acre or more), which could most easily be protected from the inroads of sheep or cattle, the exclusion of these being indispensable. ‘The seeds might be sown very close; and if only. one in ten or twenty were to vegetate, (and that is not a very sanguine expectation), a flattering foundation would be laid for ultimate success. . Having mentioned this, subject to Mr. James Hay at Gordon Castle, he observed to me, that ‘¢ it is remarkable that trees thrive naturally on the west coast of Scotland, as well as on the west coast of Norway, in some places very nearly down to the sea side; while, in several places on the east coast of Scotland, they cannot be reared at all; and therefore whatever cause of difference may lie in the sod/*, it would appear that much is owing to exposure. The expo- sure to strong, sweeping unchecked winds, seems to be the chief obstacle to the raising of timber. Hills act upon the — wind as a dam-dike does on a running stream, in producing considerable stillness or even calm upon the side from which the current flows. This consideration should induce plant- ers to begin always at the bottom of hills, and extend their plantations gradually towards the sea. A hedge upon the side next the sea, though desirable, could scarcely perhaps be reared of any.tree.or plant. Hippophae rhamnoides - (sea buckthorn) might be tried ; but Sambucus nigra (elder . bush) would probably be found preferable.” Larch, ash, sycamore, &c. Salixes. For the raising of lareh, ash, sycamore, and others, nurseries should be established in the islands themselves ; it being certain that plants resemble animals in becoming gradually habituated to particular climates and soils. In places where Salix acuminata, S. arbuscula, aquatica, * Is it not a general law over the face of the globe that the west sides of N. and §. chains, or mountainous ridges, are most steep ?—N. , . and ORKNEY AND SHETLAND ISLES. and others grow, various willows might be cultivated, suited for wicker-work and cooperage. Salix fragilis or crack- willow would grow freely ; it makes large shoots’ every season, and bears cropping admirably. It answers well for making crets, cradels, and large baskets. The name frag?- lis only intimates that the annual shoot is very easily de- tached from the trunk, the twig itself being very flexible and tough. Salix viminalis or common osier, also grows very freely, and is much in request by coopers. Salix Helix, or rose willow ; §. triandra, cr long-leaved osier ; and 8. vitellina or yellow oslfer, would doubtless succeed, 147 and they are all employed in baskct-making. To ese might be added S. Forbyana or Basket osier, for the nicer _ kinds of work ; and S. Russelliana, which would be very useful not only ne making crets and creels, but in tanning, —the bark being superior for this purpese perhaps to oak- bark. A decoction of it would form an excellent liguor in which to steep their herring nets. Molucca Beans. /T have lately observed a paper “ on the beans cast ashore in Orkney,” in Philosophical ‘Transactions 1696, No. 222, by Sir Hans Sloane. He mentions three kinds as pretty. common: the Cocoon: the Horse-eye-bean ; and the Ash- coloured nickar. The two former are the kinds which I got in the islands, in 1804. The cocoon of Sloane is evidently the seed of the Mimosa scandens of Linnzus, the Gigalobium of Brown’s ‘‘ Jamaica.” It is ‘the largest of the beans figured in Wellace’s ‘* Description of Orkney,” 1693. 2. The horse-eye-bean of Sloane is distinctly the seed of Dolichos urens Lin. ; the Zoophtalmum of Brown, who calls the seed, ox-eye-bean. This is the smaller bean figured by Wallace, and is easily known by the hilus or welt which surrounds it, and which gives it somewhat the appearance of a horse’s or ox’s eye. 3. The ash-coloured On the Mo-«- lucca beans cast ashore on . ‘Orkney. nickar is the seed of the Guilandina bonduc Lin. Itis not . so commonly found as the others. It is a perfectly round hard seed, little larger than a musket-bullet. Herring-Fishery. This immense field for industry,—this inexhaustible source y ery great 148 political ad- vantages of the herring fisher- ry of Scotland. ORKNEY AND SHETLAND ISLES. of wealth:—has been often described ; but still it isin a great measure neglected; at least we certainly do not derive from it those vast advantages which it is calculated to afford, and which it did, for a very long series of years, afford to the States of Holland. At a moment when we are listening to the eloquent and plausible, but I fear seductive and dangerous arguments of the Earl of Selkirk in favour of emigration, [ cannot omit this opportunity of very briefly calling into view the extent and the value of this fishery, which, if duly prosecuted, would afford cheerful and pro- fitable employment at home, to any number of those de- juded men who are every year abandoning their native country, in quest of imaginary happiness and riches in the woods and fens of America;—and I presume it will at once be conceded, that ten or twenty thousand Scotsmen engaged in the Shetland herring-fishery, would, in_ this eventful period, be a much more agreeable object of con- templation to the mother country, than the finest imaginable settlement in Prince Edward’s' Island, or on the banks of Immensity of the shoals, the St. Lawrence. It is scarcely possible to form an idea of the immensity of the grand northern shoal of herrings which approaches the Shetland Islands every month of June. ‘* The flocks of sea-birds, for their number,” it has been observed, ‘“ bafile the power of figures :” Where the Northern Ocean in vast whirls Boils round the naked melancholy isles Of farthest Thule ;— Who can recount what transmigrations there Are annual made? what nations come and go? And how the living clouds on clouds arise ? Infinite wings! till all the plume-dark air And rude resounding shore, are one wild cry*. “+ But the swarms of fishes, as if engendered in the clouds, and showered down like the rain, are multiplied in an in- comprehensible degree. Of all the various tribes of fishes. the Herring is the most numerous. Closely embodied in resplendent columns of many miles in length and breadth, and in depth from the surface to the bottom of the sea, the * Thomson. shoals * ORKNEY AND SHETLAND ISLES. shoals of this tribe peacefully glide along, and, glittering like a huge reflected rainbow or aurora borealis, attract the eyes of all their attendant foes*.” Let it not be thought that this swelling description ex- aggerates the amount of the shoals: let it be coolly con- sidered that for more than a century the Dutch annually loaded above a thousand decked vessels out of this grand northern shoal, and yet that this immense capture never in any year sensibly diminished the number of herrings around Shetland, which, after these foreigners were glutted, regu- larly continued to press forward toward the islands in vast bodies, frequently crowding into every creek and bay ! The Dutch, it is well known, accounted this fishery their *¢ gold mine.” It seems generally agreed among authors, that it yielded them, for a long course of years, 3,000,0001. sterling yearly. Dr. Campbell, after premising that the value of the Dutch fishery has often been exaggerated, and that he will therefore give a ‘“‘ modest computation,” pro- ceeds thus: ‘* It would however be no difficult thing to prove, to the satisfaction of the candid as well as critical inquirer, that, while it continued to flourish in their hand, they drew from their fishery out of the ocean washing the coast of Shetland, to the amount of two hundred millions sterling*.”” From 1500 to 2000 sloops were employed in fishing: this gave occasion to the freighting of 6000 more ; and thus the herring-fishery gave employment and subsistence to above a hundred thousand personst. Captain Smith, who was sent to Shetland so leng ago as 1633, expressly to report on the Dutch fishery, says, ‘I was an eye-witness of the Hollanders’ busses fishing for herrings on the coast of Shetland, not far from Ounst, one of the northernmost islands. Demanding the number of them, I was informed that the fleet consisted of 1500 sail, of 80 tons burden each, and about 20 armed ships, carrying 30 guns a piece, as convoy.” The conclusion drawn by the captain, is quite characteristic of a British sailor: it is stated with much spirit, and though his plan is not a practi. cable one, his language forcibly shews how strongly his mind was impressed with the vastness of this fishery, and the * Bewick, Introd. + Political Survey, Vol. I. p. 69F. t Ibid. absurdity 149 —which is proved by the Dutch. Amount of the Dutch fishery. Report of Capt. Smith in 1633 on this fishery. 150. Former fishery at Shetland, abandoned, Proposals for its renewal. ORKNEY AND SHETLAND ISLES. absurdity of neglecting it: ‘¢ If the King® would send ont such a fleet of busses for the fishing-trade, being in our own seas, and on our own grounds, and all strangers were dis- charged from fishing in those seas, that the subjects of the three kingdoms only may have it, it would make our king rich and glorious, and the three kingdoms happy ; not one would want bread,—and God would be praised,—and the King loved.” About half a century ago, the herring-fishery on. the coast of Shetland was very successfully prosecuted by some English companies. But, through unaccountable misma- nagement, it has for many years past been abandoned. At present, also, owing to the troublous state of the North of Kurope, this fishery is more neglected by foreigners than at any period during the last two centuries. Very few Danes, Sweeds or Prussians, I understand, now make their appear- ance. The French and Dutch dare not. " hitherto in use, and capable of moving smoothly and easily Ta without the necessity of cleaning and oiling, as long as the metal will last of which it is made. How far I have suc. ceeded, I leave to the decision of the Society. Iam, Sir, Your humble servant, JOHN: ANTIS. ey Fulneck, April 3d, 1804. ‘To Cartes PAWioR, Esa. Reference to Plate IV. Fig. I. A, shews the hole for the handle, which moves the follower Description. and latch. B, the follower which draws back the latch, on turning the handle either way. C, the latch. D, the lon- gitudinal spring, which throws out the catch of the latch when the hand is withdrawn. I, the small bolt, to secure ‘the door internally. F, the key-hole, the bolt of the lock of which is not shewn, being placed above the key-hole. * Soc. Arts. This useful contrivance was rewarded with the silver ~ medal. Q2 156 Easy remedy to prevent rain being driven into apart- ments through the interstices of window frames. SCIENTIFIC NEWS. SCIENTIFIC NEWS. USEFUL NOTICES RESPECTING VARIOUS OBJECTS. 1. Method of preventing Wet from being introduced into Rooms by Windows which shut together like folding Doors. A considerable inconvenience has been found from the wet penetrating, in rainy and windy weather, through the joints of those windows which have been called French windows, and are now much used. No accuracy of workmanship has been sufficient to remedy this evil; but, on the contrary, the closest joints have seemed rather more favourable to this effect than others less neatly made. Mr. Collinge, Engine- maker, of Lambeth Road, shewed me a very simple and easy remedy. Reasoning on the subject, he considered the close joint as a capillary interstice which would retain a continu. ous mass of water, much more disposed to be driven hori- zontally into the room by the action of the external air than to be conveyed downwards through a longer interval by its mere gravity. Hehas thercfore enlarged the space for de- scending water by ploughing out a semi-cylindrical groove in each concave angle, from top to bottom. This small space, which is about one-tenth of an inch wide, occasions no deformity, and allows the water, as soon as it arrives there, to trickle down to the bottom of the frame, where it is conducted off by a similar concavity along the horizontal frame-work to any place of external discharge which may be made choice of. This easy and effectual cure for a nui- sance which has destroyed the carpets, and occasioned pud- des i in very elegant rooms, and has apparently resisted all efforts to remedy it by close fitting, will, no doubt, be ac- ceptable to many readers. SCIENTIFIC NEWS. 157 2. Extemporaneous Printing Press, used by Country Comedians. I was informed, the other day, that it is the common = method practice of travelling companies of comedians. to print their a Stee ¢ bills by laying the damped paper upon the form of letter roller, previously inked, and to give the pressure by a wooden roller, clothed with woollen cloth. Many years ago I made experiments of this method, which I found very capable of affording impressions, by a light pressure. The form of letter must be disposed in a kind ‘of frame, having its upper surface about one-thirtieth of an inch lower than the inked face, in order that the roller, being supported by the frame, may not be obliged to rise with much obliquity, upon the first letters; and that it may pass off, at the other end, with equal ease. If some such contrivance were not used, the paper would be cut, and the impression injured at the be- ginning andend of the rolling. The roller must be passed in the direction of the lines, or across the page; otherwise the paper will bag a little between line and line, and the impression will be less neat. In fact, the common method by the plattin, or flat surface which presses the whole at once, is best; but the engine is less simple. But asthe arts of writing and of printing have incal- culably extended the knowledge and powers of man, it may be allowed us to look forward to a time when communica- tions shall be as much more rapid and effectual, compared with those of the present time, as ours are, compared with what they were before printing was invented. We may hope fora time when men shall confer more rapidly, concisely, perspicuously, and comprehensively by writing than they are now able todo themselves by articulated sounds. We may contemplate a period when by easy combinations of chemical and mechanical skill, the multiplication of nume- rous copies may demand scarcely more time and apparatus than is now required to write a single copy. And while we speculate on possibilities of this nature, which are far from ‘being in the higher class of improbabilities, we may indulge a philanthropic hope, that when it shall be more easy to cgavey, distribute, and apprehend the results of philosophi- cal and moral research, the short span of human life will be much less obscured by misery and accumulated suffering than it 158 ‘Prints or im- pressions from drawings upon stone, SCHENTIFIC NEWS. it is at present. Every step toward these ends is sory § en- titled to our notice. 3. ‘Art of Pr Ynting fro om er made upon sea Surface of gene: T am not at present j in possession of the history of an art Which ha? Béen practised for some years in this town . by several ingenious foreigners ; namely, that of printing copies from designs made on the surfacé of stone. An eminent chemist informs me that thé method’ is as follows; © Upon the surface of an honé, or close grained stone, de- signs aré to be made in the stroke manner, with a pen, by means of an ink or pigment, made of a solution of lac in leys of puresoda, with a little soap added, coloured with lamp-black; or the designs may be made vie a, crayon of the same composition. I suppose that the proportions and indnipulation would require some trials before perfect suc- cess would be obtained. When the design has been allowed to dry or harden for three or four days, the stone may be soaked in water, and its surface wetted. In this state if it be dabbed with Printers’ ink from the balls, the ink will stick to the design, but not to the naked stone, anda copy may be taken from it by applying wet paper with pressure ; whether of arolling or screw press was not mentioned, but T suppose the latter to be preferable. The advantage of this art appears to be that the print is given from an re A and not from acopy, as all engrav- ings must necessarily be. Itmay also be, considered as one ‘of the means adverted to in our last article, For if a smooth stone, or a board of close wood, or perhaps some species of tile, or other prepared surface, could be written upon by an ink which, when speedily dried by the fire, or otherwise put into a tate fit for use, could be made to afford impressions or copies by a simple roller, it would be easy.to multiply bills, orders, notices, and an infinite nuin- ber of other useful papérs, to an extent which cannot at present, be developed without much investigation and Tes search, SCIENTIFIC NEWS. 3. Gilding by means of inc. — 159 The same intelligent and active philosopher, whose name New process I forbear to mention ou] y because I have not at this instant an of gilding: opportunity of asking his permission, informs me that a coating of. brass, formed by the precipitation of zine upon copper, constitutes the surface of the beautiful gilt ,trinkets which at present abound in our shops, and are much supe- rior in their appearance, and cheaper in. price, than what were formerly made. The process is, Take of zinc one part and mercury twelve parts, with which make a smooth soft amalgam. It is better if alittle goldbe added. Clean the copper piece, or trinket, very carefully with nitric acid. Putthe amalgam into muriatic acid, and add argol (by which name the crude tartar is denoted inthe shops). Purified tartar will not do. Boil the clean ‘copper in this, and it will be very finely gilt. Copper wire, thus coated, is capable of being drawn out to the fineness of an hair, though copper alone would not. This wire is used for making gold lace, and for epaulets and ‘other similar articles. The theory of the above process appears to resemble that of whitening pins; and its useful applications may probably be more numerous than those which have yet been adopted. 4, Clock of the famous John. Harrison, which. does not require cleaning. ~ Cummings, in his Treatise on Clock and Watch Work, mentions a clock of Harrison’s which was constructed to go altogether without oil; but he does not say by what means the necessary lubricity of its moving parts was obtained. About two years ago I saw this clock in the hands of Mr. John Haley, Jun.. The pivots of the wheels moved on fric- tion rollers of considerable diameter ; and the pivot 's. of these rollers, or rather wheels, were brass, and moved in sockets of a dark coloured wood, which I think must have been lignum vite. Hence it should seem that the contrivance was re- duced to that of rendering the surfaces of contact, where the sliding or friction was to take place, as slowly moving as possible, and in presenting a face which should afford a - softish bed, having grease in its interstices. Similar to this is the practice of some mechanics, who make the bearing parts of the axis of agrindstone very smooth and round, and en- velope them with a piece of bacon-skin, which is said to be very useful to keep away the sandy particles, and facilitate the motion for along time without much wear. Harrison’s clock without TO CORRESPONDENTS. Extreme occupation during the concluding month of the year has prevented my searching into the authoritics upon which De Lalande has established his comparison of the English and French measures, and also those from “which he has deduced the measures of the earth’s radii. I shall pay attention to the request of “¢ A Constant Reader” in the next Number. Mr. Walker’s letter from Oxford arrived by the post ; but not the pamphlet. In answer to the inquiry of D. M. respecting a method of cleansing linen by the application of steam, as used by the French, I cannot point to any authentic account of a simple process of this kind, though I have been informed that the application of steam to piece goods, in a large digester, at a temperature considerably above 212°, is very effectual in cleansing, and promoting the bleaching process. This, how- ever, seems fitter for the manufactory than the laundry. IL am disposed to think that the method alluded toby D. M. is the Salzburg method, described in Van Mons’s Journal, of which a translation is given at p. 127 of the tenth volume of our Journal , containing paren instr uetions how to carry it into effect. Iam sorry that a note of R. L. Edgworth, Esq. was os noticed earlier. Four lines from the bottom of page 82 of the last volume, the following should be inserted: ‘‘ The number of teeth necessary for the wheel may. be easily cal- culated to suit the measurement ; so that the dial-plate may shew with sufficient accuracy five, or any other small number ‘of miles.” Mr. R. L. E. speaks with commendation of Mr. Gipin’s crane in that volume ; but remarks, that the groove which renders acommon chain so much preferable to a rope for heavy burdens supported by tackles, has been long used. Ihave just received the work of the Rev. P. Roberts, A.B. Dr. Bardsley, Physician to the Manchester Infirmary, has committed to the press a Selection of the Reports of Cases, Observations, and Experiments, chiefly derived from Hospital Practice ; including, among others, Clinical Histo- ries of Diabetes (with Chemical Experiments on the Nature of diabetic Urine), Chronic Rheumatism, and Hydrophobia, ee a EE i 60. Wi Wichetron's Philos. Journal . Vol VL fl. 3.P.I = a. Tr on eee . a\| l ¢' iit -f i “| Ki iM i MH : Db i Ht is im a i ee Mi 5 ( lita Man il | Hl Mt —_ i i el on ol | fi il nil py i i p i ale 4 ay My’ aa adn i i 9 @) aher | ts a 4, ae i pa v 7 i none Ai) | 4 ar ‘el I i f a 4 a | ‘ S S niu! mi mi iW i “ f ys nly \- il a al @s | lit, hy DOT eye i: 1 i! BS sit y SS Fas Mn mn i i Hit SS Lp Hp i lial ) inl AM? Andrew Elints, Expanding Band Wheel . P =i : mi ti P| ii i m4 TF Hi ya a M i! m4 ih i aR th ye \ s/ i [pet Yh m\ m\ ‘ p I va Al Fig.4 : Hi Hl (a vil ca maa HUN i . ay - “a i Dy, i ‘ un Mh H ‘ mi f 7 Nicholsonsfhitos Journal Vol XVIPA p16’. ME Antiss Door Laich . AL Peter Herberts.Book Case Bolt. ma id ¥ A JOURNAL OF NATURAL PHILOSOPHY, CHEMISTRY AND THE ARTS. MARCH, 1807. ARTICLE I. Experiments on Palm-Oil, by Joun Bostocx, M.D. Com- municated by the Author rt To Mrv NICHOLSON. Ts E appearance and physical properties of the substance Palm-oil, called Palm-Oil, are sufficiently well known; but I believe its habitudes with different chemical re-agents, have never yet been attended to. Palm-Oil, as usually imported into this country, is of a deep —its obvious orange-colour: its consistence is similar to that of butter, P°P res although perhaps, for the most part, .a little harder and less unctuous. It has an odour peculiar to itself, somewhat aro- matic, and not unpleasant. Its inflammability seems about _ €qual to that of tallow; a cotton thread, inclosed in a quantity of it, was easily ignited, and burned with a clear, bright flame. ; * In order to ascertain the melting point of palm-oil, I heated Experiments a portion of it to the 100th degree, when it became perfectly Bane ek. fluid, and then observed the effect produced on the thermo- meter by its gradual cooling. When the mercury had de- scended to the 69th degree, the oil began to be slightly opake; Voi. XVJ.—Marcu, 1807. _ )° ie at 162 PALM OIL. at 62°, it was completely so, and was of the consistence of honey: it continued to grow thicker until it arrived at 45°, the temperature of the room, when, although its fluidity was en- tirely lost, it still retained a degree of sofine’s that it did not possess before the experiment. The thermometer, as far as I could perceive, continued to descend without interruption during the whole peridd, and the oil seemed gradually to thicken in every part, without ex- hibiting any appearance of partial congelation. The inference which may be drawn from this experiment, seems to be con- firmed by the following: Two equal quantities of the palm- oil were placed in similar jars; one portion was rendered completely fluid, and was then cooled down to 69°, when it began to assume a slight appearance of opacity; the other was heated to 65°, and was just beginning to melt. Both vessels were then plunged in a water-but of 100°: a thermo- meter,inserted into each of them rose with equal rapidity, the first remaining 4° above the second. They were then re- moved, and the thermometers indicated an equally rapid decrease of heat, until they arrived at 48°, which was the temperature of the room. Equal quantities of palm and olive oil were heated, in similar jars, to the 100th degree, and then removed to a temperature of 45°: thermometers were inserted into each, and descended with equal rapidity. Habitudes. of Alcohol, at the ordinary temperature of the atmosphere, acts Palm-oil with upon palm-oil ina very slight degree only. After remaining mae in contact for forty-eight hours, the fluid is perceptibly tinged of a yellow colour; and, by the addition of water, a slight degree of turbidness is produced, owing to the precipitation of a small quantity of palm-oil. By the application of heat, alco- \ hol dissolves the oil more readily; a part of it is precipitated as the fluid cools, but a small quantity, about 1-75th of the weight of the alcohol, remains in permanent solution, and may be eeflbn al by water. —andwithsul-. Sulphuric ether acts upon palm-oil with facility, at the ordi- phuric eiker. nary temperature of the atmosphere, and produces a deep, bright yellow solution. The ether dissolves about 1-6th of its weighi of the oil, an‘ its solvent power is increased by heat. Wahen water was added, the ethereal solution rose to the sur- face, and floated on the water without being decomposed. F Palm- PALM OIL. Palm-oil is also readily dissolved by the oil of turpentine, at the temperature of the atmosphere. _The-action of caustic pot-ash upon palm-oil is similar to Palm-oil has of J€ss attraction that which takes place between the alkalies and other bodies analcaginous nature. Alter being boiled together for some than olive-sil. time, they form an opake and semifluid mass, miscible with water without decomposition, but which is slowly decomposed by the additien of an acid. In this latter case, the oil rises to the surface in small flushes, having lost its original colour and smell. The same effect, although in a less degree is produced. dy the action of ammoniac upon palm-oil. Palm-oil, however, exhibits less affinity for the alkalies than olive- oil. . Palm oil does not appear to be soluble in mineral acids, After being heated for some time in contact with them, it was left floating on the surface of the fluid, and, upon saturating the acids with an alkali, no precipitation was produced. The oil had, however, undergone a considerable change in its ap- pearance and properties, from the operation of the sulphuric and nitric acids. In the former case, it had lost its specific smell; it was of a grey colour; and was considerably less unctuous than before the experiment. Upon being immersed in boiling water, it appeared to censist of two substances, of a white friable matter, which was diffused through the water, and had partly lost its oleagmous nature, and some small drops of a blackish oil. The efiect produced by the sulphuric acid seemed to be similar to that which is described by Mr. Hatchett, in his valuable papers on the preduction of tan- ning™*, Action of the \ The oil that had been heated in contact with nitric acid was Oxidation by also considerably changed: it was of a dirty colour, of a much nitric acid. firmer texture than in its natural state, and had acquired a smell resembling that of melted wax. The appearance ot this substance seeming to coincide with the prevailing theory re- Specting the oxidation of oil, I was induced to examine how far it resembled wax in its chemical properties. First, in order to ascertain its melting point, a quantity of it was completely fused at a temperature of 110°. It was then gradually cooled 3 and when it had arrived at the 72d degree, it began to grow opake at the edges ; at the 69th degree it had entirely lost its : R 2 transparency ; * Phil. Trans, 1805, p. 11, and alibi, 164 Effects of nitric acid on palm- oil continued, PALM OIL. transparency ; and, at 65°, it was become so firm, that the ther- mometer could with difficulty be removed from it. Hence it appears that palm-oil, by the action of nitric acid, is rendered less fusible, and that its fusibility is more nearly confined to a precise limit than in its natural state. Its solubility in aleohol appeared, however, to be rather increased; 100 grs. of alcohol dissolving very nearly 3 of the oil, two thirds of which were precipitated as the fluid cooled. The tendéncy of the palm- oil to unite with pot-ash was also considerably increased by the action of nitric acid. Equal quantities of the oxidated oil, and of the palm-oil in its natural state, were boiled with twice their weight of liquid pot-ash, nearly the whole of the oxidated oil was united to the pot-ash, and formed with it a-thick sapo- naceous substance, while a considerable portion of the common palm-oil remained floating at the surface. , Nearly the same effect was produced upon the palm-oil, by being boiled with nitric acid, by being digested in it for some weeks, at the temperature of the atmosphere, or by being pre- cipitated, by the nitric acid, from its union with pot-ash. When the oil was digested without heat in the acid, its colour was first changed to a dirty green, next toa grey, and, lastly, was rendered nearly white. That, in these different processes, the oil was not united to the entire acid, but that a portion of the © - acid was decomposed, and its oxygene absorbed, I judged, Comparison with other oils because I found that the oil, after it had undergone the change, Was not in any respect altered by being kept for some time in boiling water, nor did it impart to the water the least degree of acidity. This opinion was farther confirmed, by its union with pot-ash; if the oil had contained nitric acid, the addition of the pot-ash, instead of forming soap, would have reduced the oil to its original state. After having ascertained some of the leading properties of palm-oil, it appeared an interesting object of inquiry, to exa- mine the relation that it bears to other substances, both of animal and vegetable origin, to which it exhibits some points of resemblance. I particularly refer, to the expressed oil of vegetables, butter, tallow, spermaceti, the wax of the my- rica cerifera, bees-wax, and the resin. The properties to which I particularly directed my attention, were the fusibility of the substances, and their habitudes with alcohol. The melting points PALM OIL. : 165 points of-several ofthem, I-had, on a former occasion*, taken some pains to ascertain with accuracy, on account of their having been so differently stated by authors of the first respect- ability. I now repeated the experiments with every possible care, and obtained the following results : Tallow, heated to 120°, was ati fluid and transparent; Freezing- at 992°, a slight tendency to opacity was just perceptible ; at uaa Mi 97, it Beanie very evidently opake round the edges; and at stances deter- 90°, it was no longer transparent; at 89°, it had acquired a mined, pretty firm consistence. The thermometer continued to de- scend during the process without any apparent interruption. A quantity of spermaceti was heated to the 120th degree, when it was perfectly fluid and transparent. The mercury descended to the 114th degree, when a slight opacity was perceptible at the lower edge; but it continued falling to 112%°, when it became stationary. A film then formed on the surface, and very nearly the whole was rendered solid, when the thermometer began to descend again; but, upon agitating the part that remained fluid, the mercury rose to 1123°. When the whole had concreted, the thermometer descended to the ‘temperature of the room. Upon going through a similar pros cess with myrtle-wax, heated to 120°, the opacity was ob- served to commence at the 116th degree;-but the mercury did not become stationary until it arrived at 109%°: here it »stopped until the whole became solid, when the thermometer again began to descend. Bleached bees-wax showed a slight _ degree of opacity at 148°; but 142° or 1412° was the point where the mercury became stationary. The wax, however, retained a degree of sofiness at a much lower temperature. With respect ve their fusibility, these bodies will stand in the following order—ex pressed oil; butter, palm-oil, tallow, myrtle- Wax, spermaceti and bees-wax. I had not an oyportunity of Palm-oil mefts making the experiment upon expressed oil; but butter, palm- ei a low heat, oil, and tallow are not only more fusible than the other sub-- stances, but they also agree in being liquified in a gradual man- ner; whereas the others pass more immediately from the fluid _ to the solid state, at one precise degree of temperature. With respect to the effects of alcohol, it is an opinion universally oe that expressed oil, butter, and tallow are not acted R 3 upon - * Nicholson’s Journal, IV, 153 and seq. 166 PALM OIL. Action of alco- #pon by it. This opinion, however, I found erroneous; not hy pee tin only was a small portion of each of them dissolved by being ; heated with alcohol, but even without the assistance of heat, a minute, yet very evident quantity, was taken up by the spirit. A part of the substance dissolved in the heated alcohol was precipitated as the fluid-cooled, the remainder was sepa- rated by water, or by evaporation.. The quantity was se small, that I found it difficult to ascertainits exact proportion. Method ofma- The method that I pursued with respect to the spermaceti al “<*P° and the other kinds of wax, was to add them by degrees to the boiling alcohol, until a quantity remained undissolved. This would necessarily be melted, and would form itself into a small globule, which, when the fluid was become cool, might be removed. The fluid, together with that part of its contents which was precipitated by cooling, were then thrown upon a filtre, the weight of which was previously known, and the pre- €ipitated part being retained by it, it was easy to ascertain its amount. By weighing the fluid that passed through the filtre, and by permitting the alcohol to evaporate spontaneously, the solid contents that had been dissolved in it were ascertained. In this way were discovered both the whole quantity of the body that the alcohol dissolved, and that part of it which was continued in solution after the fluid had cooled. Results of the Proceeding in this manner, I found that 100 grs. of alcohol AES oA na dissolved 52 grs. of spermaceti, half of which precipitated by stances, cooling: 100 grs. of alcohol dissolved 2.134 grs. of myrtle- wax, 1.334 grs. being precipitated by cooling, and 1-8th gr. ‘held in permanent solution. The same quantity of alcohol dissolved only .31 gr. of bees-wax, almost half of which was precipitated. The order in which these substances will stand, recording to their power of resisting the action of alcohol, will be, olive-ol], butter, and tallow, nearly the same, bees-wax spermaceti, palm-oil, and myrtle-wax. The order of fusibility is, therefore, not exactly the inverse of the order of solubility in alcohol. The affinity of these several substances for the alkalies nearly follows the order of their fusibility, although not exactly so, tallow appearing to unite with caustic pot-ash more readily than with palm-oil. With respect to the resins, their fusibility and their solubility in alcohol, differ considerably in the different species ; in ge- neral, Their attrac- tion for alkalies ~ Habitudes of Resins. CALORIMETER. 167. ~ neral, however, they are less fusible, and more soluble in alcohol than any of the bodies mentioned above. It appears then, upon the whole, that palm-oil differs essentially in its physical and’ chemical properties from any substance that has hitherto been’ made the subject of experiment. Its fusibility is nearly similar to that of animal fat, while, in its chemical properties, it more nearly resembles the resins, at the same time that it differs from those bodies in not being soluble: i in nitric acid. Liverpool, Feb. 14, 1807. 0 I, Description and Use of a Calorimeter or Apparatus for deter- mining the Degree of Heat, as well as the Economy attending the Use af ceriey kinds.of Fuel. By M, MonTGoLrien. Pine. proper use of fuel is one of the most important objects Advantages of in all the processes of the Arts, and more especially in Che- economy, &c, fuel. mical Operations; and it is an object of no less utility, to de- sia termine the advantage and economy attending the uses of the various descriptions of fuel and the intensity of heat disengaged from the substances burned. The same quantity of combustible matter of different kinds Different com- bustibles vary does not always afford the same degree of heat, and a longer in their effectsi or shorter portion of time will be required to disengage it from © ' each combustible respectively. The success of an operation frequently depends on the rapidity with which it can be per- formed. Manufacturers, distillers, and cultivators must there- _fore consider it as an object of great importance to know what kind of fuel may be the cheapest for use, and what may be the proportion of a given quantity of the’ one compared with the same quantity of another, with regard to the effect to be derived from each ; or, in short, whai may be the most certain and easy method of determining the difference of the’action of heat. The editors of the Journal des Mines speak with appro- bation of Mr. Montgolfier, for the instrument of which they have given a description, at the same time that they remark, R 4 that 168 CALORIMETER, that it very essentially differs from the instrument invented many years ago by Lavoisier and La Place. Description of the Calorimeter. The Calorime- Plate 5, exhibits a section of the Calorimeter of Montgol- ter described. fier, ABCD isa vessel or hox of tin, which might, with more economy and advantage be made of wood, sufficiently ee well constructed to hold_water. In its cover A B, there is a stove within an opening a; and so likewise, in the bottom, is an open-: it, and a de- ing ¢ f. Within this vessel is a small. stove, abcde f, of scending flue ‘ ras ie erchimney. plate-iron, or, which is better, of copper, carefully closed, so that no water can enter into it. Its lower opening corresponds with that of the exterior vessel or box, ef The other open- ing, inthe other part is closed near a, by a oa which can be taken out at pleasure. ed isa grate composed of iron wire, upon ‘while the fuel is put, the ashes fall through the grate, and escape’at the open- ing g- Nearhi is fitted a tube, &%, through which the smoke escapes by the opening 7. This pipe must be made of iron or copper plate, sufficiently close to prevent the water from pene- traling. my isa pipe of plate iron, surrounding the last- mentioned in such a manner as that the water may be placed in. the place between them, LEisa reservoir, of which the. cover, rs, can be taken off, in order to fill the apparatus with, water. oo is a pipe proceeding from the same reservoir, and com- municating with the pipe m m. 2 nis another pipe, which passes from. m_m, into. the vessel, for the purpose of introducing water, after it has passed through the pipe m m. p isacock, through which boiling-water may be suffered to escape ; and q is another cock, by means of which the appa- ratus may be emptied when needful. th F G are the legs which support the apparatus. Use of the Calorimeter. Method of When it is required to determine the time in which different sing it. combustibles disengage, an -equal quantity of heat, the reser- voir ¢ is to be filled with water. The fluid passes through the tube 00, ‘rises through mm, and thence, by an, into the vessel ABC D, A sufficient quantity must be poured to fill . the CALORIMETER. ~ 169 the whole internal capacity of the vessel, which is easily known when the water does not descend below the line ¢u, or the most elevated station of that fluid in the apparatus: and the temperature must then be noted by a thermometer. A suffi- Cient quantity of the fuel, for the purpose of an experiment, must then be taken; for example, wood cut into small pieces, and placed in the gratec d. After setting fire to it, the upper By arty ng Opening ab, of the stove, is to be Baga, and notice taken of or a the time employed in raising the water to a certain heats for the water, the example, that of boiling, which may be ascertained bya ther- sesalbog Aha mometer. At this period the fire isto be taken out, and the are known. water and the apparatus suffered to cool to the first tempera- ture at which the operation commenced. Another kind of fuel; for example, pit-coal or turf is then to be disposed on the grate cd, and pi same SPR ba made, after setting it on fite. “The greater or less rapidity with which heat is disengaged from the combustibles, will be known by comparing the times of the experiments respectively. ““Trorder to find the difference in the quantity or weight of —and by the combustible matter of different kinds, proper to produce the “oeegieiat i - ue! consumed equaily-elevated temperature, it is necessary to take of one of their economy the combustibles, for example, wood, a sufficient quantity, sup- is determined: pose one cubic foot. . This is to be set on fire in the stove, after it hath been filled with water, and the temperature noted. The thermometer determines the period at which the water boils ; and, at this period, the fire must be extinguished, and all the fuel taken out which remains on the grate. And when the whole has been brought to its first temperature, the process must be repeated with the other combustibles; for example, turf or pit-coal. - ~ If, after the operation, the quantilies of combustibles made use of be estimated at a medium price, it will be easy to show the cost of one compared with that of the other, and, conse- quently, what fuel is the least expensive. ““ We may also observe, that the external pipe m, may be made of wood; but if it be plate-iron or copper, it will be proper to cover it witha number of sheets of paper, forming a thickness sufficient to prevent the ready escape of heat. “The Pipes, kk and mm, Hap: bd lengthened at pleasure, because 170 INFLAMMABLE GAS FROM COALS. because a considerable portion of heat escapes through the aperture C. The economi- . This apparatus may he used for different purposes; such as cal use of the that of boiling water at a small expence. It is of great utility present appa- - ratus. in domestic concerns. In order that its effect may be com- plete, the heated air ought to be deprived as much as possible of its caloric. . The author, or perhaps the editors of the Journal des Mines, proceed to observe, that the cooled air being heavier than that of the atmosphere, causes the current in this kind of stove, and therefore they recommend that the __ descending tuhe should be made as long as local convenience Error of the in- inventors. willallow. It would not be needful to take notice of this over- sight, if it were not accompanied with the practical deduction. The.current is, in fact, produced by the rarefaction of that part of the air which ascends, and not by any increased density in the descending part, which, by the condition of the experi- ment, is, for the most part, in contact with hot water, and never colder than the surrounding atmosphere, Ill. | esis Letter from Mr. Hume, of Long Acre, respecting the Carb retted Hydrogen Gas procured from Coals, by Dr, CLayto N; early in the last Century, To Mr. NICHOLSON. SIR, As an addition to the information already before the public, respecting the Hydrogen, or Catburetted Hydrogen Gas pro- cured from Coals, it may not be improper to refer at once to an authority, beyond all others the most authentic and easy of access, I mean the Philosophical Transactions. In the 41st uma volume of that work, p. 59, there is a short paper on this sub- the inflamma- ject, describing how the discovery originated, and some of the tig from effects produced by this gas, or spirit. of Coals, The paper appears to have been read before the Royal Society, in Jae nuaty, 1739, as, “aletter to the Hon. Robert Boyle, from the late Rev. John Clayton, D. D.” : This 7 EONCERNING THE WIND. 17th » "This letter is evidently a posthumous publication, and there- fore may have been copied from that quoted by your corres _pondent Mr. Webster. However, lest there be any doubt, one being by John, the other by James Clayton, it is but fair to make both authorities known, in order that the merit of this discovery may no longer be disputed, nor claimed by any per~ son living. I am, Sir, With much tespect, Your obedient Servant, Long Acre, Feb. 10, 1807. Jos. Hume. IV. Curious Obs servations on the Wind, byRocERAsuam. Ina Leiter from a Correspondent ae To Mr. NICHOLSON. SIR, In the English works of Roger Ascham, which were re= fatroductory printed at London, in quarto, anno 1761, under the care of AREP 2 200m ‘James Bennett, I find a number of curious particulars; one of AME Roger As~ which I am tempted to send, for the information of your cham, readers. In his Toxophilus, or School of Shooting, which relates to Archery, the subject is handled ina manner truly scientific and orderly, and such as is eminently calculated to show by what care and attention our ancestors obtained their pre-eminence in that celebrated art. The passage1 now send you Constitutes part of a dissertation on the effects which the direction and force of the wind, and the state of the air, may have in preventing the archer from striking his mark. In our time, these observations will be taken as bearing a more general relation to the mass of atmospheric phenomena, But I will ‘not detain you with longer preface. “I copy from p. 168, but _@o not follow the ancient orthography. =] _ Tam, Sir, Your obedient Servant, R, B. « The oii . Nea Lond. 172 CONCERNING THE WIND. Course of the “ The wind is sometimes plain up and down*, which is wind. commonly most certain, and requires least knowledge, wherein. a mean shooter, with mean gear, if he can shoot home, may make best shift. A side wind tries an archer and good gear very much. Sometimes it blows aloft, sometimes hard by the ground, sometimes it bloweth by blasts, and sometimes it con- tinues all in one ; sometimes full side wind, sometimes quarter. with him and more, and likewise against him, as a man with casting up light grass, or else, if he take good heed, he shall sensibly learn by experience. To see the wind with a man’s eye, it is impossible, the nature of it is so fine and. subtle; yet this experience had I once myself, and that was in the great snow that fell four years ago (1540). I rode in the. — obsérved on highway betwixt Topcliffe upon Swale and Borowbridge, the oe of way being somewhat trodden before by wayfaring men: the fields on both sides were plain, and Jay almost yard deep with snow: the night before had been a little frosty, so that the snow was hard and crusted above. That morning the sun shone bright and clear, the wind was whistling aloft, and sharp, according to the time of the year: the snow in the highway lay loose, and trodden with horses’ feet, so as the wind blew, _, » it took the loose snow with it, and made it so slide upon the test snow in the fields, which was hard and crusted by reason of the frost over night, that thereby I might see very well the whole nature of the wind as it blew that day, and I had a great de- light and pleasure to mark it, which makes me now far better — varying in to remember it. Sometimes the wind would be not past two he een yards broad, and soit would carry the snow as far as I could eal ena see, ; Another time, the snow would blow over half the field at once; sometimes the snow would tumble softly, by and by it would fly wonderfully fast. And I also perceived that the wind goes by streams, and not together; for I could see one stream within a score of me, then the space of two score ‘no snow would stir. But afier so much quantity of ground, another stream of snow at the same time should be carried likewise, but not equally; for the one would stand still when the other flew apace, and so continue, sometimes swifter, some- times slower, sometimes broader, sometimes narrower, as far as I could see. Now it flew straight, but sometimes crooked this way, * From the context it appears that, by plain up and down, the Author mcans direcily to-or from the mark. MARINE BAROMETER. 178 way, and sometimes it ran round about in a compass. And — and also in sometimes the snow would be lifted clean from the ground up direction, &c. to the air. and by and by it would be all clapt to the ground, as though there had been no wind at all; straightway it would risé and fly again. And that, which was the most marvellous of all, at one time two drifts of snow flew, the one out of the west inio the east, the other out of the north into the east. And I saw two winds by reason of the snow, the one. cross over the other as it had been two highways; and again, Ia, currents heard the wind blow in the air, when nothing was stirred at of air at the the ground. And when all was still where I rode, not very S#m¢ time far from me, the snow should be lifted wonderfully. This experience made me more marvel at the nature of the wind, that it made me cunning in the knowledge of the wind ; but yet thereby I learned perfectly that it is no marvel at all, though men in wind lose their length in shooting, seeing so - many ways the wind is so variable in blowing. *« But seeing that’ the master of a ship, be he never so cunning, by the uncertainty of the wind, loses many times both life and goods, surely it is no wonder, though a right good archer, by the selfsame wind, so variable in its own na- ture, so insensible to our nature, loses many a shot and game. Se EN ST ee ee ee V3 Observations on the Marine Barometer, made during the Exami- nation of the Coasts of New Holland, and New South Wales, in the years 1801, 1802, and 1803. By Matuew Frinpers, Esq. Commander of his Majesty’s Ship Investigator, in a Letter to the Right Honourable Sir JoserpH Banxs, Bart. K. B. P. R.S., Xe. §e. From Philosiphical Transactions for 1806. [Concluded from Page !18.] \ | HE greatest range of the mercury observed upon the last Observations : z -,.:.. and inferences coast, was from 29, 60 to 30, 36 at Port Jackson; and within Suaccenaentae the tropic from 29, 88 to 30, 30; whilst upon the south coast, correspondent the range was from 29, 42 to 30, 51, in the western part changes of . é ? wind and weas« where the latitude very little exceeds that of Port Jackson. It ther, to be ex- is to be observed, however, that these extremes are taken for pected after ; (ea, change in the very short intervals of time. marine baro- : yY meter, 174 MARINE BAROMETER’ Observations ~My observations upon the north coast of Australia are but and inferences fittle satisfactory, both because the changes in the barometer to ascertain the ° . : correspondent Were very small in so lowa latitude, and that very little more changes of — than the shores of the gulph of Carpentaria could be exa- - ane ney mined on account of the decayed state of the Investigator, pected after which obliged me to return with all practicable expedition to pitied Nig Port Jackson. An abridged statement, however, of the gene- meter. ral height of the mercury under the five following circum- stances, will afford some light upon the subject, and perhaps not be uninteresting, 1st. On the east side of the gulph, and at the head, with the south-east monsoon, or trade wind. 2d. At the head of the gulph with the north-west monsoon. 3d. On the west side during the north-west monsoon, 4th. At Cape Arnhem under the same circumstance; and 5th. In the passage from Cape Arnhem, at a distance from the coast, to Timor, with variable winds. : In a memoir written by Alexander Dalrymple, Esq. F. R. S. respecting the Investigator’s voyage, there is this ge- neral remark ;—** Within the tropics, the monsoon blowing on “« the coast produces rainy weather, and when blowing from “ over the land, it produces land and sea breezes.” This I found verified on the east side of the gulph of Carpentaria, be- tween November 3 and 16, which time was employed in its examination ; for though we had found the south-east trade to blow constantly on the east side of Cape York just before, and doubtless it did so then, yet in the gulph we had a tolerably regular sea breeze, which set in from the westward at eleven or twelve o'clock, and continued till seven, eight, or nine in the evening. ‘Towards the head of the gulph, the trade wind, which blew at night and in the morning, came more from the NE, and the sea breezes more from north and NW, but without producing any regular alteration in the height of the mercury, whose average standard was 29,95; it never fell be- low 29,90 or rose above 30,04. At the head, the height of the mercury remained nearly the same, until the north-west monsoon began to blow steadily, about the !0th of December, two or three days excepted, when the day winds were from the south-eastward, and the mercury then stood between 29,80 and 29,85. At these times, however, there was usually some thunder and lightning about, signs of the approaching rainy + MARINE BAROMETER. 175 rainy monsoon, which may perhaps account for the descent of o> -rvations the mercury independently of the direction of the wind. and inferences 2d. On the confirmation of the nort%-west monsoon, there '° #scertain the correspondent was a change in the barometer at the head ofthe gulph, the changes of common standard of the mercury being at 29,88; but during wind and wea- ; ? i 4 : ther, to be ex- the times of heavy rain, with thunder, lightning, and squalls of pected after wind, when amongst the islands of Cape Vanderlin, the mean Change in the height was 29,79. The north-west monsoon, after coming aay peer over Arnhem’s Land, blows along the shore for a considerable part of the space between the Cape Maria and Cape Van Die- men, of Tasman; and during the examination of the parts so circumstanced, we sometimes had tolerably fine weather, and the mercury above 29,90; but the wind was then usually more from the north than when the mercury stood lower. As we approached Cape Maria, and the bight between it and the south side’ of Groote Eyland, the mercury stood gradually lower; and in the bight, where the north-west monsoon came directly from off the shore, although we had sea and land breezes with fine weather, according to Mr. Dalrymple’s general position, yet the mercury was uncommonly low, its range being from 29,63 to 29,81: the average 22,74, below what it had stood in the very bad weather near Cape Vander- lin. These winds and weather, and the low state of the mer- eury, continued until we got without side of Groote Eyland. 3d. ‘On the east side of Groote Eyland, and the west side of the gulph, northward from that island, we: sometimes had sea and land breezes with fine weather; we had also two mo- derate gales of wind from the eastward, of from two to four days continuance each, with one of which there were heavy’ squalls of wind and rain ; sometimes also, the winds were tole- rably steady between north and west, with fine weather. Du- rmg all these variations, the mercury never differed much from its average standard 29,90; and it seemedas if the increase of density in the air, from the wind blowing upon the coast, was equal to its diminution of quantity from the fall of rain and strength of the wind; and, on the other side, that the wind from over that corner of Arnhem’s Land permitted the mer- cury to descend, as much as the fine weather would otherwise have occasioned it to rise. Upon the north side of Groote Eyland, the mercury stood et higher 176 MARINE BAROMETER. eal higher than usual for five days, and.during this time the wind — and inferences blew with more regularity from NW, the only exception being to ascertain the for a few hours in the .@fternoons, when it commonly sprung up pete aaa from the NE in the manner of a sea breeze: the weather re- wind and wea~ mained fine during these five days, and the height of the mer- reat aa cury averaged 29,94. change inthe 4th. In the neighbourhood of Cape Arnhem, the mercury minal baro- usually stood about 29,90, whether the wind was from NW, NE, or east, if the weather’ was fine ; but if by chance the wind shifted to the south side of west, off the land, it descended to 29,80 though the weather remained the same: and this was its standard during those times when strong gusts came from the NW accompanied with heavy rain, thunder, and light- ning. F In this example, the wind from SW occasioned the mercury to stand lower than that from NW in the same weather; which is contrary to what was observed upon the south and east coasts; particularly on the former, where the south-west wind elevated the mercury up to, and sometimes above 30,25. , 5th. On March 6, 1803, we made sail off from the north coast, towards Timor, the north-west monsoon having ceased to blow at Cape Arnhem, and the eastwardly winds appearing to have set in; but we soon outran them, and had the wind so variabie and light afterwards, that it took us twenty-three days to reach Coepang Bay, a distance ofno more than 12° of lon- gitude. The only two remarks I made upon the barometer during this passage were, that the common height of the mer- cury was 29,95 at those times that the wind remained steady for some hours, from whatever quarter it came, and about 29,85 when it was most unsettled; and that it stood higher, upon the average, after we had passed Cape Van Diemen, when the south-west winds, which blew oftenest, came from the sea, than it did before. The medium height of the mercury, deducting the time be- tween Cape Maria and Groote Eyland in the 2d example, I should take at 29,92, which, when the quantity of rainy squally weather; with thunder and lightning, is considered, is very high: the whole range of the mercury upon the north coast was four-tenths of an inch, The MARINE BAROMETER. 17% ~ The principal differences in the effect of winds upon this Observations coast, from what they produced upon the south and east coasts, 2nd inferences to ascertain the ate, that a north-east wind raised the mercury as high, if not correspondent higher, than one from the SE; and that a north-west wind, tg ary Where if camie froin off the sea and was moderate, was equat to ee enc. either of’ them, and kept it up higher ay the south-west pected after change in the wind did. marine baro- In order to have ascertained the full effects of sea and land meter. Winds upon the barometer, it was desirable to have learned, whether the south-east winds, which occasioned the mercury to rise highest upon the south and east coasts, would have left it at the medium standard, or made it descend upon the north- west and west coasts of Australia; but, unfortunately, the state of the ship did not permit me to determine this; for at the dis- tance we kept from these coasts, in making the best of our way to Port Jackson, the accumulation of air over the shore, arising from a sea wind, or the contrary from a land wind, can scarcely be supposed to have much, ifany effect. The princi- pal winds we experienced between Timor and Cape Leuwen, in the months of April and May, were from SE and SW.. Vhe south-east wind prevailed as far as the latitude 25°, and the mercury stood at first with it at 29,95; but as we advanced southward, it rose gradually to 30,25, nearly in the same way as it had before descended on the east side of Australia, when we steered northward in the month of October. This wind was succeeded by an unsteady northwardly wind, ‘which brought the mercury down to 29,99; but on its veering by the west to SW it rosé fast, and fixed itself about 30,32: we were then drawing near Cape Leuwen. . As far as this example can be admitted in proof, it appears, thata wind from the SW has an equal, if not a superior power to one at SE in raising the mercury upon thé west coast; which was not the case upon the south, and still much ie upon the east and north coasts, where the south-west wind “caused it to fall, Winds from the northward caused the mer- cury to descend, as I belive they always will in the southern hemisphere, ifnot obstructed by the land; but upon the north coast, we have seen ‘the mercury stand higher with it than al- most any other. _ Upon a summary of the effects ofthe same winds upon the _ Vou, XVI. — Marcu, 1807. S different $1 Fe 178 MARINE BAROMETER. Observations hg, Gh ere different coasts of Australia, as deduced from the above exam to ascertain the Ples, the following queries seem to present themselves : es tg a Why do the winds from north and NW, which cause the ene and wea- Mercury to descend and stand lower than any other upon the ther, to be ex- south and east coasts, and also in the open sea, and in the ered ae south-west bight of the gulph of Carpentaria, make it rise upon marine baro- the outer part “of the north coast, with the same, or even worse Meher: weather? Why should the north-east wind, which occasions a fall in the barometer upon the south coast, considerably below the mean standard, be attended with a rise above the mean upon the east and north coasts ? The south-east wind, upon the south and east coasts, caused the mercury to rise higher than any other; why should it not have the same effect upon the north coast, and upon the west ? How is it that the south-west wind should make the quick- silver rise and stand high upon the south and west coasts,— should cause it to fall much below the mean standard upon the. east coast,—and upon the north, make it descend lower than any other, with the same weather ? The answer, I think, can only be one; and it seems to he sufficiently obvious. The cause of the sensibility of the mercury to winds blowing from the sea and from off the land, may perhaps admit of more than one-explanation; but the following seems to me to be direct, and tolerable satisfactory. The lower air, when brought in by a wind from the sea, meets with resistance in passing over the land; and to overcome this resistance, it is obliged to rise, and it will make itself room by forcing the superincumbent air upwards. The first body ofair, that thus comes in from the sea, being itself obstructed in its velocity, will obstruct the second, which will therefore rise over the first in like manner to overcome the obstruction ; and as the course of the second body of air will be more direct towards the top of the highest part of the land it has to surmount, than the first was, so the first part of the second body will arrive atthe top, before the latter part’ of the first body has reached it; and this latter part will be able. to pass over the -top, being sept down by the second body and the successive stream of air, whose velocity is superior to it. In this manner, an eddy, or body of compressed, and comparatively inactive air will be formed, which, at first, will occupy all the space below a line drawn MARINE BAROMETER. drawn from the shore to the top of the highest land : but, almost immediately, the succeeding bodies of air, at a distance from the shore, will feel the effect of the obstruction ; and being 1m- pelled by those that follow them, will begin to rise, taking their course for the top of the highest land, before they come to the shore ; by which means, the stratum of lower air will be ; deeper between the top of the land and the shore, and to some distance out from it, than itis either upon the mountains or in theopen sea. Ifthis is admitted to be a necessary consequence of a wind blowing upon the shore from the sea, it follows, tnat the mercury ought to stand something higher when such a wind blows, whether it is from the south or any other quarter, than it will with the same wind where it meets no such obstruction 3 and the more direct it blows upon the coast, and the higher the land is, (all other circumstances being equal,) the higher ought the mercury to rise: On the other hand, when the wind comes from off the hills, this dead and dense air-will be dis- placed, even from its hollows under the highest land ; both on account of its own expansion, and because its particles will be attracted by those of the air immediately above, which are taking their unobstructed course out to sea; and thus the air over the coast will resume its natural state with a land wind. In order to appreciate duly the effect of sea and land winds upon the barometer, in the preceding examples, it is neces- sary to be recollected, that in the southern hemisphere, a wind ‘from the south has a natural tendency to raise the mercury in the open sea, and one from the north to depress it; probably, from the superior density of the air brought in by the former ; therefore, if the mercury rises quicker and higher with a south wind upon the scuth coast, then it does with a north wind upon the north, it is not to be at once concluded, that the effect of the wind as coming from the sea, is less pon the north coast ; for it has, in the first place, to counteract the tendency of the mercury tofall with a north wind; and, in some cases, its effects as a.sea wind may be as considerable, relatively to the latit»de, where there shall be no rise in the barometer, as upon the south coast it might where a considerable one took ‘place. The same thing may be said of the winds from the east and from the west ; for where the vicinity of land is out of the question, the former generally causes an ascent (from what principle, I leave others to determine,) and the lattera descent in the barometer, and I ; $2 believe 179 Observations and inferences to ascertain the correspondent changes of wind and wea- ther, to be ex= pected after change in the marine baros meter. 180 MARINE BAROMETER, Observations believe this extends to both hemispheres, and allclimates. The aa pana rs wind from SE then, which combines something more than half correspondent the power, both of the south and of the east wind, will raise changes of the mercury higher than any other on the south side of the re pee ey equator, and the wind from NW permit it to fall lower, inde+ pected after pendantly of their effects assea and land winds; and this al- rec in the Jowance requires to be first made upon them: the south-west arine baro- . micter, aud north-east quarters should be equal where there: is no land in question, and of a medtum strength between the power of © the south-east, and the deficiency of the north-west wind. [leave it wholly undetermined, whether the effects of sea and Tand winds upon the barometer, as above. described, extend beyond the shores of the country where these observations were made, and to about one hundred leagues of distance fromthem ; but it seems not improbable, that they may be found to take place near the shores of all countries similarly circumstanced5 that is, upon those which are’ wholly, or for the most parts surrounding by the sea, and situated within the fortieth degree of latitude, In colder climates, where snow lies upon the, ground during a part ofthe year, the wind from off the land may perhaps be so cold, and the air so much condensed, as to pro- duce a contrary effect; but this, and ihe prosecution of -the subject to other important consequences, I leave to the philo-, sopher ; my aim being only-to supply my small contribution of raw materials to the hands of the manufacturer, happy ifhe ean, make them subservient to the promotion of meteorogical science. I will conclude with stating a few general remarks upon the barometer, such as may be useful to seamen. It is notso much the absolute, as the relative height of the mercury, and its state of rising and falling, that is to be attended to in forming a judgment of the weather that will succeed; for it appears to stand at different heights, with the same wind and weather, in different latitudes. Vo} sans wn In the open sea, it seems to be the changes in the ig and in the strength of the wind, that prinkiell affeet the. barometer ; but near the shore, a change in the'direction of , the wind seems to affect it full as much, or more, than either of those causes taken singly. , It is upon the south and east coasts of any country in the southern, or the north and east coasts, in the northern hemi-. sphere MARINE BAROMETER. 181 sphere, where the effect of sea and land winds upon the baro- 4. atone meter is likely to be the most conspicuous. and inferences In the open sea, the mercury seems to stand higher in a oh ae steady breeze of several days continuance, from whatever Bases of quarter it. comes, provided it does not blow hard, than when wind and wea- the wind is variable from one part of the compass to another ; raed a iia and perhaps it is on this account, as wellas from the direction change in the ofthe wind, that the mercury stands higher within the tropics, aoe ae than, upon the average, itappears to do in those parallels - where the winds are variable and occasionally blow with vio- lence. The barometer seems capable of affording so much assistance to the commander of a ship, in warning him of the approach and termination of bad weather, and of changes in the direction of the wind, even in the present state of meteo- rological knowledge, that no officer ina long voyage should be without one. Some experience is required to understand its language, and it will be always necessary to compare the state of the mercury with the appearance of the weather, before its prognostications will commonly be understood; for a rise may foretelan abatement of wind,—a change in its direction,—or the return of fine weather ; or, if the wind 1s light and variable, it may foretel its increase toa steady breeze, especially if there is any easting in it ; and a fall may prognosticate a strong breeze or gale, a change of wind, the approach of rain, or the i dying away of a steady breeze. Most seamen are tolerably good judges of the appearance of the weather; and this judgment, assisted by observation upon the quick or slower rising or falling of the mercury, and upon its relative height, will in most cases enable them to fx upon which of these changes are about to take place, and to what extent, where there is only one; but a combination of changes will be found more difficult, especially where the effect of one upon _ the barometer is counteracted by the ther: as for instance, the alteration of a moderate breeze from the westward with dull, or rainy weather, to a fresh breeze from the eastward with fine weather, may not cause any alteration in the height of the mercury ; though I think there would usually be some rise in this case. Many combinations of changes might be men- tioned, in which no alteration in the barometer would be ex- pected, as a little eonsideration, or experience in the use of 5 3 this 189 TURQUOIS STONE. this instrument, will make sufficiently evident; the barometer alone, therefore, isnot sufficient; but in assisting the judgment of theseamen, Is capable of rendering very important services to navigation. SO OS OE ES ETRE VI. Analysis of the Substance known by the name of Turquois.: By M. Bovititon LAGRANGE. Many Mineralogists have placed the turquois among calcareous bodies and the genus called opake; and others, on account of their blue or green colour, have classed them among the ores of copper. Chaptal’s ac- « The turquoises, (says M. Chaptal) are merely bones co- Teton ake loured by the oxides of copper. The colour of the turquois often passes to green, which depends on the state of the me- tallic oxide ; the turquois of Lower Languedoc emits a fetid smell by the action of fire, and is decomposed by acids; the turquois of Persia emits no odour, and is not attacked by acids. Sage suspects that the osseous part is azatized in those left.” Places where Many turquoises are found in Persia, but none in Turkey, they are found 45 its name seems to imply. They are obtained from two mines: the one, called the Old Rock*, at three days journey to the north-west of Meched, near Nichaburgh; the other, at - five days ‘ourney, is called the New Rock. The Turquoises of this last place, are of a bad blue, inclining to white, and are therefore cheap. But since the close of the last century, the King of Persia has prohibited the Old Rock to be explored, except for himself; because the workmen of the country work- ing only in wire (en fi/), and not being acquainted with the art of enamell ng on gold, they made use of it for the mounting of sabres, poignards, and other tools, turquoises of this mine, instead oi enamel, by cutting and setting them in different forms. I shall add some other details, extracted from different works 3 ¥ Annales de le Chymie, LIX, 180. ; La Harpe’s Abrégé des intial VI, 507. # TURQUOIS STONE. 183 works; in which I am indebted to the kindness of the cele- brated mineralogist M. Haiiy. Turkis (turquois) Reuss, page 511, part 2, 2 vol. 3. The Turquois has always been considered as the tooth of Various ac- an unknown animal, of which the sky-blue colour depends on eo oxide of ‘copper; or, according to others, on oxide of iron ; different au« which has caused it to be ranked in the calcareous order, and thors. sometimes in that of copper, as animal petrefaction (odonta- lite.) Lommer, in the 4éhandlungen einer Privat-Gesellschaft in Beh- men, 2 vol. page 112, 118, thinks the turquois is a produce of art. He asserts, that a tooth found in the neighbourhood of Lissa, in Folomie, being exposed to a strong heat in the muffle of an assayer’s furnace, became converted intoa turquois; and he recommends the heat to be very gradually raised, for fear the tooth should fly in pieces. Bruckman gives a complete history of all that has been Supposition written from Pluds to Lommer, on the turquois. He mentions that the tur- mount Caucasus as a place of origin, at the distance of four Be ane < days journey from the Caspian Sea ; where, according to Chai- stance. din, this stone is dug up. It is likewise in Persia, Egypt, Arabia, and in the province of Samaveande. Dambsy brought it from Pert; some of them contained nae tive silver. The occidental turquois is found in France, at Simore, in Lower Languedoc, in Bohemia, in Siberia, and in Hungary. Demetrius Agaphi, who visited the place where the tur- quois is found, near Chorasen, in the neighbourhood of the town of Pishepure, relates, in the fifth reer der Nordischen Beitrage, 1793, page 261, that the turquois is found in a stone as its matrix, in masses and small points; and that it might be ~ considered as a peculiar mineral, which has the same situations as opal, the chrysophane, and the resiniform quartz. Mr. Bruckman, in Creil’s Chemical Journal, 1799, vol. 2 page 188 to 199, thinks, from the nature of its position at Cho- rasan, and after the analysis at Lametz, that the turquois is not a petrefaction of parts of animals, but a particular mineral. Lonsitz obtained from it, by analysis, much clay,’a little cop- per, and iron; but neither lime, nor phosphoric acid *. $4 According * I donot know whether the substance analyzed by M. Lowitz, | 184. - TURQUOIS STONE. The oriental According to Meder, the oriental turquois is found in a pri- jeencaed mitive Se AP emo schistus, of a grey bluish, or black greyish ® petrefaction. colour, which excludes all supposition of petrefaction. Graphic schistus, and quartz, are found in the same place. In the argil- ? _laceous schistus, the turquois is found disseminated; and it. is the same with quartz, and the graphic schistus. To remove every idea that the turquois cannot be consi- dered as malachite, or green-copper (Kupfergriin), Meder has, given the following character : Its colour is apple green greyish ; when it begins to soften, it, is decomposed, and assumes a mountain-green colour; when completely decomposed, it is gf a yellowish white, green, and near straw colour. é {tis commonly found disseminated in small superficial parts, and seldom in masses ; its interior structure is dull, or scarcely sublucid; its fracture compact, and the fragments irregular with sharp edges, opake when it is decomposed, and more or less transparent at the edges. Its hardness varies according to the degrees of its decomposition, it is easily broken, and its specific gravity, according to Curwan, is between 2,500, and 2,908. The turquoises are not all of equal hardness: this must be attributed to the differences of the boney substances which con- te their base. The degree of pctrefaction must also in- fluence this property. The turquois, in the solid form, is sometimes mixed with ‘the brown earthy oxides of copper. - M. Meder infers, from all these characters, that the turquois ought to be placed between the opal and the chry- sopaze, with which it appears to agree by the varieties of green. Cuivier consi- Lastly, the celebrated Cuivier, in the Journal de Physique, 2g a nt page 263, vol. 52, thinks that the turquoises, namely, those teeth, coloured which are found near Simore, in Languedoc, and near Trévoux, by copper. are the cuperferous teeth of an petal resembling that which has been found near the Ohio, or the mammoth of the English and Americans ;, the carnivorous elephant. Mr. Reaumuralone has given some detail respecting the mines of turquoises, and the nature of the substances there found. can? His ought to be considered as a turquois, or, as a particular mineral; but I am more disposed to think it was not asin all the turquois. I have. examined, and found hme and phosphoric acid. D, L. TURQUOIS STONE. 185 His memoir is printed among those of the Royal Academy of Beisiowe fr Sciences, for the year 1715, which may be consulted for every par eg ¢ e thing which bears relation to the situation of the mines, and the extraction of the turquoises. With regard to the experiments made by the author, in or- der to discolour these substances, though not very conclusive, it appears to me, nevertheless useful, to bring together these facts along with the means which I have employed to ascertain the nature of the stone. I shall first present a few fragments of this part of Reaumur’s memoir. we hae The colouring matter, says theauthor, which fills the cellules p ours obs of the turquois, and which afterwards tinges the whole stone, servations on is, no doubt, a particular substance; but is it a simple mineral shaedican matter, like cobalt, or the material from which azure and sap- phor are made, from which the finest blue of porcelain, and pottery is served; or, isita metallic matter? I have not been able to satisfy myself in this respect. Lat first suspected that our turquoises might probably derive their colour from copper. This metal is capable of affording a blue, anda green... ... But Ihave found that the turquoises » ..:takonup may be extracted like that of coral ; of all the solvents, which I by vinegar. have used, distilled vinegar succeeded the best. If a thin piece of turquois be steeped in this vinegar, its angles, after an hour or two, become white ; and in two or three days, the whole of the upper surface of the stone, and even its internal parts, assume the same colour. Vinegar, while it extracts the colour, likewise dissolves the stone; it is always covered with a kind of white cream, com- posed of parts which have been detached. Juice of lemons likewise dissolves this kind of stone, but it only weakens the colour; and that which is found under the kind of cream, we have described, is blue, when the stone has been put into this liquid, _ As to aquafortis, and aquaregia, they are not proper, to ema ciatortis. ee tract the colour from our turquoises ; they very speedily dissolve applied to the whole substance of the stone, but they afford the means of these stones. distinguishing the Persian turquoises from those of France. Aquafortis does not act upon those of Persia; whence it fol- lows, that these two kinds of stone, though similar in ap= pearance, are nevertheless of a very different nature ; it would be wrong, however, to draw a consequence to the disadvan- i tage 186 TURQUOIS STONE. ange of our stones, by concluding that they have less tena- city. Aquaregia likewise acts differently upon these two kinds of stone. It totally dissolves ours, and it reduces ‘those of Persja into a kind of paste, more whitish than the turquois . was, but which is not, nevertheless, deprived of we its blue co- lour. Tarquoises In general, this kind of stone has a singular defect; namely, lose their co- that, without the assistance of any other agent than that of time, dour, and their sete colour changes: insensibly their blue assumes a shade of value by time. § y ~ i green, they become greenish, and at last green; whereas the colour of other precious stones is unchangeable. When the’ turquoises have become green, they are no longer of any value; the convention of society has placed: them in no estimation whatever with that colour. Chemical Examination. Characters of | Physical characters. Specific gravity, 3.127.—Colour, light the turquols. green and blue; surface, smooth or polished; hardness, such as slightly (o scratch glass; difticult to-be pounded; powder, greenish grey; fracture, polished. Habimde with Chemical characters. Before the blow-pipe, it loses’ its the blow-pipe. colour, and becomes ofa greyish white, but does not melt. Heated in a crucible of platina, it acquires the same colour, but becomes friable, and is easily reduced to powder. In this experiment it loses 6 per cent. of its weight. Soluble in mi. Lhe nitric and muriatic acids totally dissolve the turquois. _neral acids. The solution, in the latter acid, is yellow; and that in the’ nitric, is colourless. The nitric solution presented the following phenomenon :— 1. with lime-water, a white flaky precipitate—2. by ammonia in excess, a precipitate of the same colour, but more abun-- dant: the supernatant fluid did not acquire any bluish tinge - —3. carbonate of ammonia likewise gave a precipitate— 4. with the oxalate of ammonia, the precipitate was very light and very. divided—s. precipitate of pot-ash gave a deep blue precipitate. - . These preliminary experiments aiready afford an approxi- mation toa knowledge of the constituent parts of the turquois ; they are not sufficient to lead to a regular classification. I therefore chose out of a certain quantity of turquoises, those. which Nitric solution. TURQUOIS STONE. 187 which were the most coloured and the most hard, and [I sub- mitted them to the following experiments : A.—100 parts of turquoises, reduced to powder, were intro- Analysis solu- duced into a small retort: and 300 parts of nitric acid, at Pe tae 36 degrees, were poured in. After some time, a slight effer- acid escaped. avescence appeared, which lasted -till the svlution was com- plete. The gas being collected in the pneumatic apparatus with mercury, presented all the characters of carbonic acid gas. B.—This nitric solution is white, and of the consistence of syrrup. It was then evaporated to dryness, and the remaining matter made red-hot in a crucible of platina. C.—The calcination had scarcely changed its colour. The dissolved . . : : 4 matter was a This substance was again dissolved in water, acidulated phosphate. with nitric acid, with the intention of separating the iron, which might exist in the state of oxide. But the whole was entirely dissolved, which evidently proves that the iron was neither in the state of red oxide nor in that of nitric, but in that of phosphate. D.—Ammonia in excess was poured on the liquor C, which Small portion gave a white precipitate of considerable bulk. This precipt- aap tate, after washing and drying, was treated with concentrated . liquid pot-ash, which dissolved a certain quantity. The liquor of the non-dissolved portion was afterwards separated from the liquor, and muriate of ammonia added, which separated a white substance, possessing all the properties of alumine. This substance, after the calcination, weighed one -part and a half. E.—The portion dissolved by the pot-ash was also calcined, and its weight proved to be 82 parts. ‘ F.—Being desirous of ascertaining whether the liquor, from Lime. experiment D, did not contain lime in solution, carbonate of ammonia was poured on the fluid, and a precipitate was ob- tained, which, being slightly dried and heated, was found to be carbonate of lime. — Its weight was 8 parts. _ G.—The supernatant liquor was afterwards evaporated, but it afforded no precipitate ; whence it may be concluded, that it contained n» magnesia. H.—Being persuaded beforehand that the precipitate E Iron. contained phosphates, it was treated with the sulphuric acid. The matter was afterwards washed, and the waters being put together, 18§ TURQUOIS STONE, together, precipitate of pot-ash was poured on, which- formed a precipitate of a fine deep blue, of which the weight, after calcination, was found to be one part anda half. It was red oxide of iron. Care must be taken to heat the liquor, in order to separate the precipitate entirely. The supernatant liquor held in solution the acid phosphate of lime, which was shewn by the phosphorus it afforded, when treated with charcoal. Atraceofmag- 1.—This oxide of iron was heated again with a little pure gancse, + pot-ash, When the whole was in fusion, the matter assumed a deep green colour, and when the cold mass was afterwards dissolved in water, it gave the same colour to the fluid. Upon adding a small quantity of muriatic acid, it became of a fine rose colour. This experiment was repeated on a number of turquoises, and the phznomenon always took place; which evidently shows the presence of a very small quantity of magnesia, aad manga- K.—Being desirous of ascertaining whether the turquois: creat contained phosphate of magnesia, as the experiments of Four- croy and Vauquelin upon bones, lead to suspect, I treated this substance according to the method indicated by those chemists, in the 47th volume of the Annales de Chymie. It was found that 100 parts of the turquois contained two parts of the! phosphate of magnesia. Component Fram the preceding experiments, it follows that 100: parts parts. of turquois contain Phosphate of lime.) au pininfos ott tema SO Instead of 82, found in experiment KE. Deducting the quantity of phosphate of magnesia, before mentioned . . + « OO Carbonate, of lime, 4: 2 ojeece/is vteaioen 8 Phosphate. Qh arn. ini. «it cely tricestayis tubal eae of magnesia. ifp sAvicen (emuecetsnae of manganese, minute quantify 0 ALQMING -. 6061 ain a tcaeiae te. Van > one .. Waterand slogs..so:.» iia vapid) aicierise ee ate ye 100 ae Though I obtained similar products in the examination of uoi1ses fs a ! ° x is same na- Several turquoises, it cannot yet be decided whether they be ture asthose jndentical. The turquoises used in. my experiment are pers here examined fectly aa TURQUUIS STONE. . 189 fectly similar to those in the Cabinet of Museum of Matural History; and M. Hauy, whom I consulted, could not afirm whether they were truly from Prussia. M. Guyton thinks that there is a difference between the turquoises of Persia and the Occidental. "This philosopher has announced, for several years, in his course of mineralogy, at the Polytechnic School, that the former contained silex. It is possible that turquoises may contain this earth accidentally ; but I have not found it in any of those _ which I examined. This difference ought not, I think, te suspend the classification of this substance by minetalogists. M. Guyton himself has already placed it among fossil bones, This celebrated chemist ‘has likewise made some comparative experiments. He has found that fossil bones assume, in thé fire, a colour similar to that of turquoises; that, when digested in. waler containing pot-ash, they turn blue; and that this blue varies in its shade, by passing from greenish blue to deep Bits blue ; and, lastly, that bones, exposed to’ the air, become white. Messrs. Fourcroy and Vauquelin have likewise observed, that bones, strongly calcined, often assume a bluish tinge: this colour appeared to them to be owing to the presence of a small quantity of phosphate of iron. _ There cannot, therefore, any longer exist a doubt respecting Observation the matter which colours the turquoises. If it were necessary 2°4 ¢xperi- to add any thing more to the facts announced, [ should observe, p Sialeenecin that having put the same turquoises which I analyzed, into the matter. hands of Mr. Vauquelin, he did not find a particle of copper - in them; and, lastly, I have ascertained that, by pouring into a. solution of muriate of lime, phosphate of soda and some drops of muriate of iron at the maximum, the phosphate of. lime and of iron is obtained, of which the colour is a greenish: blue. We may, likewise, by decomposing the phosphate of soda by muriate of iron at the maximum, obtain a phosphate of iron, which is not white, as some chemists have asserted, but of a gréen bluish colour. These reflections, without doubt, are not very important; but I present; them as tending to show, the possibility of imi- tating the colour of the turguois, and at the same time to ‘show that iron can, in various circumstances, afford colours; similar to those of copper. | : ria Wks 190 METHOD OF FEEDING COWS. Vil. Account of Mr. Curwen’s Meruop of Feepinc Cows, during the Winter Season, with a View to provide poor Persons and Children with Milk at that time.. SIR, Preface. Eyery attempt to ameliorate the condition of the labouring classes of the community, is an object not unworthy of public attention ; and has, on all occasions, been zealously patronised by the Society of Arts. Under this impression I hope for the in- dulgence of the Society in calling their attention to an experi- ment, which I flatter myself will, in its consequence, prove not only highly beneficial to the lower orders of society, but tend “ likewise to the advancement of agriculture. Great benefits There is not any thing, 1 humbly conceive, which would to be expected conduce more essentially to the comfort and health of the froma plentiful supply of milk labouring community and their families, than being able to procure, especially in winter, a constant and plentiful sup- ply of good and nutritious milk. Under this conviction, much pains have been taken to induce the landed proprietors to assign ground to their cottagers, to enable them tokeep a milch cow. The plan is humane, and highly meritorious ; but unfortunately its beneficial influence can reach but a few, Could farmers in general be induced from humanity, or bound by their analdrasd to furnish milk to those, at least whom they employ, it would be more generally serviteable. Even those who have the comfort of a milch cow, would find this a better and cheaper supply, as they can seldom furnish themselves with milk through the winter. The farmer can keep his milch cows cheaper and better; for, besides having green food, his refuse corn and chaff, of little value, are mghly serviceable in feeding milch cows. General no- My object is to combat the prevailing opinion, that dairies tion thatdairies . are not profit- i summer are more profitable than in winter. TI confidently able in winter. hope to establish a contrary fact. ‘'Theexperiment I am about to submit to the Society, is to prove, that by adopting a dif- ferent method of feeding milch cows in winter, to what is in general a METHOD OF FEEDING COWS. 19% general practice, a very ample profit is to be made, equal, i not superior to.that made in any other season. I believe the prin ciple will hold good equally in all situa- tions; my experience is confined to the neighbourhood ofa large and populous town. _ The price of milk is one-fifth higher in winter than in sum- mer. By wine measure the price is 2d. per quart new milk, ld. skimmed. My local situation afforded me ample means of knowing ycal simuation how: greatly the lower orders suffered from being unable to of the author, © Procure a supply of milk; andI am fully persuaded of the correctness of the statement, that the labouring poor lose a ‘number of their children from the want of a food so pre-emi- nently adapted to their support. Stimulated by the desire of making my farming persuits Con- Experiments of tribute to the comfort of the public, and of those by whose 4 different means my farm has been made productive, I determined to try ie 63 the experiment of feeding milch cows after a method very diffe- rent to what was in general practice. I hoped to be enabled thereby to furnish a plentiful supply of good and palatable milk, with a prospect of its affording a fair return of profit, so as to induce others to follow my example. The supply of milk, during the greatest part of the year, in all the places in which I have any local knowledge, is scanty and precarious, and rather a matter of favour than of open ijanc, ~ Consonant with the views I entertained of feeding milch provision. cows, I made a provision of cabbages, common and Swedish turnips, kholrabi, and cole seed. I made use also of chaff, - boiled and tated” with refuse grain and oil cake. I used straw instead of hay for their fodder at night. _ The greatest difficulty, which I have ed te contend with, has been to prevent any decayed leaves being given. The ball only of the turnip was used. When these precautions were attended to, the milk and butter have been excellent. Having had no previous knowledge of the management ofa dairy, my first experiment was not conducted with that fruga- lity requisite to produce much profit, sold the first season, between October 1804, ‘ac the 10th The first expes of May 1805, upwards of 20,000 quarts of new milk. Though peronts my return was not great, I felt a thorough conviction that it a : proceeded 192 Accounts, statements of the feed and produce. METHOD OF FEEDING COWS, proceeded from errors in the conduct of the undertaking; and that, under more judicious management, it would not fail of making an ample return, which the subsequent experiment will prove. In the mean'time I had the satisfaction of knowing that it had contributed essentially to the comfort of numbers. In Oct. 1805, my dairy recommenced with a stock of 30 milch cows ; a large proportion of these were heifers ; and in general the stock was not well selected for giving milk; for they were purchased with a view of their being again sold as soon as the green crop should be exhausted. Ifthe plan be found to answer under such unfavorable circumstances, what may not more experienced farmers expect ? By the end of this present month, I shall have sold ft i of 40,000 quarts of milk. The quantity of food, and its cost, are as follow. The produce of milk from each cow upon 200 days, the period of the experiment, iscalculated at no more than 6 wine quarts in the 24hours: this is to allow for the risk and failure in milk of some of the heifers. A good stock, I have no doubt, would exceed § quarts in the two meals, which would add 1007, to the profit. Daily cost of feeding one milch cow : Two stone of green food (supposing 30 tons of green “crop onan acre, at 4d. per stone would pay é- 51. per acre) at 4d. per stoneofl4éo. = - O O. OF Two stone of chaff boiled, at 1d. per stone - O O Two los. of oil cake at 1d. per Jd, costing from 8/. to 9/. per ton =. > - Pe Orme Eight dbs. of strawat2d. perstone - - (0 0 4 Z O26, 3k The chaff, beyond the expense al boiling, may be consi- dered as entirely profit to the farmer ; 2d. per stone for straw, likewise leaves-a great profit. ‘Turnips also pay the farmer very well at $d. per stone. Expense of feeding one milch cow for 200 days, the period upon which the experiment is made; 200 days METHOD OF FEEDING Cows. 193 200 dayskeep of one milch cow, at the rate of 53d. £. S d. _ perday - - - a Tt, 8 Attendance - ° - 2 0 0 Supposed loss on re-sale - * 20. 9 SB jchde 8 Return made of one milch Cow in 200 days milking : Z £.. Su ide 6 quarts per day, at 2d. per quart, for 200 days 10 0 O Calf - - - - 20 0 Profit on 20 carts of manure, Is. 6d, each me olay BOs sO 13. 1050 eee Clear gain upon each milch cow £4.18 4 ree This gives a profit upon the whole stock of £.147 10s. Observation on The profit of another month may be added before a supply of the onsider- milk can be had from grass, which will make the balance of ale obs profit 167/..18s. 4d. This profit, though noi as lage as it ought to have been, had the stock been favourable for the ex- periment, far exceeds what could be made of the same quantity of food by fattening cattle. Were the two quarts to be added which ona moderate computation might be expected, the gain would then be £.267 16s. 4d. The trifling quantity of land from which the catile were supported, is a most impoitanf consideration. One halfoftheir food is applicable to no other purpose, and is equally employed in carrying on the system ofa corn farm. Ihave tound oii cake of the utmost advantage to my dairy, promoting milk, and contributing greatly to keep the milch cows in condition. The best method of using it, is to grind it to a powder, and to mix it in layers and boil it with the chaff: half the quantity in this way answers better than as much more given in the cake, besides the saving of 2d. a day on each beast. ‘This I was not aware of on my first trial. The oil cake adds considerably to the quantity and richness of the milk without affecting its flavour. The refuse corn was. likewise ground and boiled: it is charged also at 1d. per pound. “I Vor. XVI1.—Marca, 1807. T make Toa The milk was better in quali- ty than usual. Produce of butter usually had from milk. Comparative statement. General nimi- rical deduc- tion, METHOD OF FEEDING cows. make use of inferior barly to great advantage. A change of food is much to the advantage of the deaty. Potatoes steamed would answer sas ied ; but near towns they are too expen~ sive. que By repeated trials it was found that 7 quarts of strippings, wine measure, gave a pound of butter, while 8 quarts of a mixture ‘of the whole milk was required to produce the same weight. Contrast this with milk produced from the feeding of grains, 20 quarts of which will scarce afford a pound of butter. The Agricultural Report of Lancashire, treating on the milk in the neighbourhood of Liverpool and Manchester, states 18 quarts with a band churn, and 14 or 15 with a horse churn. In a paper published by the Bath ' Society, 12 quarts are said to give a pound of butter: but wether ale or wine measure, is no specified. ‘A friend of mine, who feeds his milch cows princi- pally on hay, finds 16 wine quarts will not yield more ea 17 ounces of butter, and this upon repeated trials.: The milch cows, treated according to my new plan, have been in excellent-order both seasons, and are allows te be © superior to any in the neighbourhood. Cole seed I have found to be the most profitable of all green erops for milk; and it possesses the further adyantage of standing till other green food is ready to supply its place. ’ To ascertain the benefit and utility of a.supply_ of milk, both to the consumer and the public will be best done hy c comparison: To prove this, let us contrast the price of milk with other articles of prime necessity, and consider how far it affords a greater produce from a less consumption of food. I cannot here omit observing, at a moment when Great Britain can hope for no further cooly of grain from the’ conti- nent, and must look for and depend on her own resources for feeding her population, every mean by which the quantity of victuals can be augmented, isan object of great public concern, Each milch cow, yielding 6 gnats of milk per day, fur- hishes, in the period of 200 day s, 2,400 pounds of milk, or 171 ‘stone of 14 pounds, equal to twice her weight, supposing her ‘ina state fit for killing, with a third less food, and at one half less. expense. The. milk costs» £.10 3 . whilst , the same weight of butchers meat at 6d. per pound would amount to + £-60. Taking METHOD.OF FEEDING Cows. Taking the scale of comparison with bread, we shall find @ Winchester bushel of wheat of the “usual weight of 4 storie and 44 46. when manufactured into flour of three sorts yields ; Of first flour - Bist. 9 tb. Of second - 0) 7 Ib. ° Of third - 0) FeAlb, 3 9 lb. Lost by bran, &c. - 0 9£lb. The present cost is 10s. 3d. 2,400/b. of the three sorts of flour will cost £.23 3s. 9d. To make it into bread, allow Is, per bushel, which makes the cost of bread £.26 10s. 9d. or - something more than 23d. per ib. exceeding twice the price of the same weight of ‘aide To furnish 2,400és. of bread, requires 47 bushels, or the average produce of two-acres of wheat. Three.acres of green food supplied 30 milch cows oi 2 _ stone each of green food for 200 days. Two stone of hay each for the same period would have required ’75 acres of hay. Chaff can scarcely be considered as of any value beyond the manure it would make, which shows the profit of keeping milch cows in all corn farms. Certificates of the quantities of milk sold and money a accompany this. If the Society of Arts, &c. thinks the experiment worthy their notice and approbation, I shall be highly flattered. At all events, I trust they willaccept it as asmall tribute of respect and gratitude for the many favours conferred upon their mao do) ot Obedient and very humble Servant, J. C. CURWEN, Workington Hall, April 18, 1806, To Dr. C. Tayzor, Secretary. ‘nines Ca Vl. 195 196 FORGED IRON VESSELS, VII. Some Account of the Manufacture of Forged Iron Vessels, at Fromont. By M. Cu. Hersarr.* SSPE OCR ST Te operations of forging vessels of cast iron may be vessels of forg- divided into three distinct parts: Ist, the method of forging the ed iron, for cu- Biabiyabud ntier plates; 2d, that of forging the cake or parcel; 3rd, the cold uses. hammering Of those we shall speak in the order here men- tioned, which is likewise the order of fabrication. To Forge the Plates. The iron for this manufactory must be very soft and malle- able. It has usually the form of bars, ten or twelve feet long; each bar having the form of a long truncated square pyramids This form is necessary in order to obtain plates of different diameter, The small base is a square of ten lines, or twelfth of an-inch, and the greater eighteen lines. The assistant puts one of these bars in the fire, and when the heated part is ignited, the master forgeman earrfies it to the small tilting hammer, which is not different from those used in drawing out steel bars. He places the bar on the anvil, not upon one of its faces, but on an edge, as, in this position, the iron is less subject to crack. According to the size of the plate intended to be hammered ott, the ‘workman strikes a greater or less portion of the bar, presenting it in all situations to the hammer, in order that the plate may obtain a circular form. Between theplate and the bar itself, he fashions a small neck to facilitate its separation. In this manner, the workman continues to forge the plate on both its faces as long as the heat allows, after which he carries the bar to the anvil, and applies a cold chissel to the neck, upon which his assistant strikes in order to'separate the platefrom the bar. This last is then re- turned tothe fire, in order to continue the operation in making a second plate. Sometimes, but this is only when the plates are small, the workmen make three at once. When a sufficient number of plates has been thus fabricated, as they are of different sizes, namely, from three or four inches diameter % Journal des Mines, No, 112. FORGED IRON VESSELS. 197 diameter to a foot, the workman disposes them in parcels, of So ‘which each contains four of equaldimensions, and then carries Sa for sah one of them to the hearth of the furnace, where the assistant linaryandother takes them in the large tongs, Fig. 1, P].VI, and puts them into "*** the fire, taking care to change their position often; and when the brass is red hot, the master workman, who holds a small pair of tongs in each hand, carries it under the tilting hammer, after having spread charcoal powder between the plates, to pre- vent their welding together. The two pair of small tongs have the form of Fig. 2, and are used to give a circular motion to the parcel, and to keep it on the anvil. When he has finished hammering it, he changes the order of the four plates, and in making this change, he is careful to take notice whether any of them have cracked; and where he perceives any crack, he applies the cold chizel, ora wedge to the place on which the assistant gives a blow. After having changed the situation of the plates in sucha manner that the two outside plates become the interior ones, he places this parcel on the hearth, and takes another set, which the assistant has caused to be heated, and he subjects this to the same operation of the hammer. In this manner the process is conducted until the required dimensions are obtained, namely, after five or six heatings. He then places the plates on the ground to cool; and when cold, he cuts them circularly one at a time, with the large hand-shears, Fig. 3. This being done, each face of the plate is severally covered with a mixture, formed of the oxide of lead and oxide of tin, pulverized and mixed with alittle water; or, instead of this mixture, clay, dilated in water, may be used, as I have seen practised, Either of these will prevent the plates from weld- ing feather and for that purpose it is that they were Rate aN . Forging the Cake. “The Heilbiesd tke seven plates of the same size, coated as before described, with the oxide of lead and tin, and he places them upon each other. These seven being placed on two others of larger size, constitute what is called a cake, which is put into the fire by means of large tongs, not differing from the former, except in the mouth, or ciaws, which are rather pepsta and curved,-as is seen in Fig. 4, | ce T 3 When - 198 FORGED IRON VESSELS. p dae eee of . When the cake is red hot, the assistant, who always has the e? iron for cy. Management of the fire, takes it to the edge of the furnace, linary andother Where the master workman bends the two large plates in one Uses. part, and takes up the cake with the tongs already mentioned, Fig. 2, when he carries it to anvil of the small forge hammer, in order to bend the edge of the two great plates entirely round. The difference between the diameter of the great and small plates, is about two inches: when this is done, he puts the cake again into the fre; and when red hot, he carries to a smaller caking hammer and that used before, but fixed and movedin the same manner. The anvil is a rectangular parallepipedon, which rises above the ground not more than one foot; and it -has three pieces of iron bended toa right angle, at the height of the angle, which affords three branches converging towards the anvil, and serving to facilitate the operation of moving the cake during the work next to be described. See the plan and elevation traced, Fig. 10. The workman being seated before his hammer, takes the cake with two small pair of tongs, and gives it a continual circular motion: during this commencement of the work, he hammers it only on the edge, .after which he ignites it, he again carries it to the same hammer, first wetting the edge of the plates to diminish the heat which would only incommode him. By this second forging, he carries his stroke nearer to the center, still continuing the circular motion. By repeating the same opera- tion as far as for eight times, cantinually appreaching the cen- ter, the edge rises every time, and the assemblage of plates _ become more and more hollow. Accordingly, as this figure en- creases, he finds it necessary to change his tongs for others, which differs from the first in the elevation of one of the jaws, and the extremity.of the handle, Fig 5. After seven or eight ignitions, he carries the cake to a kind of anvil, the form of a figure 6, where he holds it with small tongs, Fig. 7, in order to complete the sides, which is done by the workmen hammer- ing in succession; the hammer of the assistant being heavy and double-handed, when this is upon iwo at once. It ts speedily done,.and followed by another nearly similar on the bottom of . | the vessel, by a second hammer, placednear the first, striking on akind of square anvil. Young girls, afterwards, are employed in scraping the bottom with an iron rod, Fig.9. One phe an FORGED IRON VESSELS. 199 and a half in length, terminating at one of its ends in a flattened Fabrication of small termination of steel. After this is done, the workman Véss¢ls of forg- ed iron for cu- takes three vessels, one afier the other, and presents them un- jinaryand other der a third hammer, placed near the two first, and moved like uses. them by the same arbor, which carries a small tripping wheel, moved by water. The vessel is placed on the anvil, so that the hammer, which is pointed at its striking extremity, enters ‘into its cavity. The workman “holds the vessel, and shifts its position with his hands and knees. Every stroke of the ham- mer leaves a slight ‘cavity of the size of a pea, which forms dif- ferent designs, according to the motion which the workman gives to the vessel. These outlines are not made for the sake of beauty, but to give strength and firmness to the vessel by hammer hardening it. The young girls, afterwards, take the vessels and scrape the interior sides, as ‘was done with the bot- tom; and lastly, the workmen, on two kinds of anvils, the one plain and circular for the bottom, and the other semi cylindric for the sides, completes. their figure with a wooden mallet. Small cracks sometimes appear in the vessel, which the work- man close, and the matter is suffered te cool; after which, the cake, which now has the form of a tuencated cone, is carried against a piece of iron bended two ways, Fig. 8, and drove into the wooden block, which supports the gudgeon of the ar- bor of the hammers. ‘This doubly recurved iron serves to retain the cake which enters under it, and by that means allows the small tongs, Fig. 7, to raise up the edges of the two great plates, which, in part, covered the seven smallones. This being done, the vessels, or hammered pieces, are taken out from within each other. ‘The first is always perforated on ac- count of the immediate purchase of the hammer, and that of ‘the air, which, partly converted into scales, fall out by the immediate action of the hammer. As these vessels, when taken out, are more or less bended, the assistant sets them to. right by a few strokes of the hammer, after which the master workman cuts their edges with the shears. it Cold Hammering and finishing. After the vessels are cut round, they are delivered to ano- ther workman, who takes them to his separate shop to finish. His first operation is to set the conical surface fair by means of | a small 200 Astronomical . circle of two fect in dia- meter, —applicd to determine the declinations of ASTRONOMICAT CIRCLE, a sinall hammer, upon a proper tool. 'The workman ‘holds the vessel with his right hand with his small tongs, 7; and with his left hand, without tongs, taking care to turn it round conti- nually. Sometimes he performs this operation witha stroke of the hammer; and the complete finish is made by cutting the eages with scissars, similar to those before described. The furnace made use of is a simple forge furnace, and the fuel is chareoal of fir, excited by wooden bellows. sient tent cateeeilseliinlilanatth sda cietsobi salah dente sirda en Sid aadininndhinendehiameedeee IX. Description of an Astronomical Circle, and some Remarks on the Construction of Circular Instruments. By Joun Ponp, Esq.* ‘ From the Philos. Transactions, \ 1806. Tl HE observations which accompany this paper were made at Westbury in Somersetshire, in the years 1800 and 1801, with an astronomical circle of two feet and a half diameter, constructed by Mr. Throughton, and considered by him as one of the best divided instruments he had ever made; a drawing of it, with a short description, is anexed to the ob- | servations. ( Plate VII.) : When this insrtument came into my possession, I 1 dita dn I could not employ it in a more advantageous.manner, than in some principal endeavouring to determine the declinations of some of the Stars. principal fixed starst. The various catalogues differed so much from each other, and such doubt existed as to the ac- curacy of thove which were thought most perfect, that the . declinations of few stars could be considered as sufficiently well ascertained for the more accurated purposes of astronomy. The * The title of this Paper, in the Transactions, is, ‘‘ On the Decli- nations of the principal fixed stars, witha description,” &c but on account of the extent of the tables of observations, 1 must refer the astronomical reader to -he Transactions for'them. The number of, stars, observed at Westbury, were 29; and of those compared with the Greenwhich observations, 57.—The plate could not be fash’ till the next Number. + At that time Dr. Maskclyne’s late Catalogue was not pubhened. ASTRONOMICAL CIRCLE. \ The advantages that have resulted from the ‘excellent 201 Method of ob- method persued at Greenwich, of observing constantly the serving, é&c. transits of a few stars, to obtain accurately their right ascen- sions, induced me to follow the same method for determining their declinations ; and fora considerable period J constantly observed them on the meridian, whenever they passed at 2 convenient hour; usually reversing the instrument in azimuth at the end of every day’s observation; never considering any observation as complete that had not its corresponding one-in a ‘short interval of time. When this circumstance is not \at- tended to, I think, a great part of the advantage arising from the circular construction is lost. The observations themselves will show, if they ,have been made with the requisite care and attention to merit the notice of astronomers ; for it is one of the many advantages ofcircular instruments, that, from the observations made with them, we may infer with great precision not only the mean probable error, but likewise the greatest possible error to which they are liable. © From a careful comparison of the errors of collima- tion, as deduced from different stars, I concluded that the greatest possible error was 2 "5, andthe mean error about 1”; and by acomparison with other observations with similar in- struments, it will be seen that this supposition was well founded, since nearly the same quantities are, deduced by another method to be considered hereafter. ; ~The polar distances are annexed to each observation: a method which I borrowed from Mr. Wollaston, and which Accuracy of the observa- tions. Greatest error of collimation. Polar distances is rendered veryeasy by employing his useful tables calculated for that purpose. This practice of reducing every day’s obser- vations cannot be too mucii recommended, as the labour of calculating accumulated observations is thus rencered un- necessary. When I ‘had idilned the declinations of these stars from Comparison my own observations, continued long enough to divest them of ali error, except that arcising from defect in the divisions of the instrumént. [-was-desirous of comparing them with the observations made bythe others; and | have subjoined a com- parison of them with all those which I could procure, that seemed entitled to confidence. In the first column are the With other obe servations. observations made at Greenwich, as published in 1802 by —namely, at the Astronomer’Royal; the second column, contains a ¢ata- Greenwich, at Armagh, at logue Palermo, and 202 by the author at Westbury. General cata- logue. New correc- tion of the la- titudes from the deviations of observations ASTRONOMICAL CIRCLE. logue deduced from some observations made at Armagh with a very large equatorial instrument, constructed by Mr, Troughs ton ; in the third column, are the observations of Mr. Piazzi; of Palermo ; and in the fourth, those made at Westbury. » All the above mentioned observations are arranged in the order of their polar distances, and the positive deviations separated from the negative ; that the cause of error in any of the instru- ments, may be the more easily detected, as likewise any mistake in the assumed latitudes of the respective places of observation. A general catalogue is then ‘added ;. which is deduced, by taking the mean, generally of the above’ four; ‘but in some places, a few detaclied observations that I have) accidentally. procured: of other circular instruments, have been included. The utility of this investigation is not merely confined to the determination of the polar distances of the stars; as, besides this, some valuable information on other points may be obtained, In the first place, upon examining the variations that appear in these observations a question naturally occurs, whether, by changing the assumed latitudes of the respective places of observation, a nearer coincidence might not be obtained? And I find, that to make the positive deviations equal to the nega- tive, the following corrections re be applied to the cos latitudes ; a ms Greenwich —}- ong revi add) ¢ ibe “ Armagh + ie yet ot Palermo way" Westbury — 0",25. This method of correcting the latitudes has, I believe, neve; been employed ; but it seems reasonable to suppose, that, when thus corrected, they will be nearer the truth, than those deter- mined by the usual method: for the same reason, that the de- clinations ofthe stars resulting from a general comparison, are mote likely to be accurate, than if deduced from any one single set of observations; but if the Greenwich instrument should be affected with any errors independant of the divisions,, in that case, we should be unable to infer any thing: decisive; as to the latitude, by the above method. But from a compa- rison of the observations of y Draconis, observed at Greenwich and Westbury, the latitude of Westbury being previously cor- rected by the above method, Iam inclined to believe the latitude of Greenwich requires a very small correction, certainly ASTRONOMICAL CIRCLE. 208 certainly not exceeding a second. The result I obtain by a very careful investigation by methods, entirely independent of the Greenwich quadrant, is 51°.28’.39",4, : : : : : /: : : The compari- - A consider this comparison as interesting likewise on ano oor opcery. ther account ; it is an object deserving of curiosity to examine the present state of our best astronomical instruments, and to ascertain what may reasonably be expected from them. The superiority of circular instruments is, I believe, too univer- sally admitted, to render it probable that quadrants will ever again be substituted in their place. But the Greenwich quadrand is so intimately connected wih the history of astrono- my, the observations that have been made with it, and the deductions from those observations, are of such infinite impor- tance to the science, that every circumstance relating to it cannot fail of being interesting Now, when it is considered that this instrument has been in constant use for upwards of half a century, and that the centererror, from constant friction, would, during this time, havea regular tendency to increase, it will not appear at all surprising, if the former accuracy of this shows the pre- instrument should be somewhat impaired. With a view, Sent iat of therefore, of ascertaining more correctly the present state of an pea ed 162 instrument on which so mych depends, J] have exhibited in one view the polar distances as determined by circular instru- ments alone; the respective co-latitu::2s being previously cor- rected by the method above mentioned, and I have compared the mean result with the Greenwich Catalogue, that the na- ture and amount of the deviations may be seen} and ifit be judged necessary, corrected. I should add, that by some observations of the sun at the winter solstice in 1800, the difference between the Greenwich quadrant and the circle was 10 or 12", the quadrant still giving the zenith distance too little. General Description of the Instrument. The anexed plate represents the circle in its vertical position. Description of It was originally made to be used likewise as an equatorial the author’s instrument, a circumstance I need not have mentionned, but el ne Na as an apology for slightness of its construction, which the Troughton. artist, who made it, would not have recommended, had the instrument been intended for the vertical position only. The 204 ASTRONOMICAL CIRCLE. Decl. circle. The declination circle, 30 inches in diameter, is composed of two complete circles ; the conical radii of which are inserted at' their bases in an axis about twelve ‘inches long, leaving suf- ficient space between the limbs for a telescope 34 feet long, and an aperture of 23 inches, to pass between. The two cir- cles are firmly united at their extreme borders by a great nums ber of bars, which stand perpendicular between them; the whole. of which will be readily understood by referring té)the figure. The square frames, which appear as inscribed in the circle, were added to give additional firmness to the whole. The circle is divided by fine lines into 5’ of a degree; and subdivided into single seconds by two micrometer microscopes, the principles and properties of which are now too well known to require any particular explanation. Greatimprove- At the time these observations were made, the microscropes ment that the were firmly fixed opposite to the horizontal diameter; but oe of When I considered that, by continuing the observations, the having their _ error of division would never be diminished, I suggested to Mr. “peppse varied Troughton the possibility of giving a circular motion to the y a circular . é - motion of the Microscopes; though I confess with very little hope, that the diameterwhich thing was really practicable in an instrument previously con- connects them. OM hag structed on other principles. Mr. Troughton approved of the idea, and executed it in a very ingenious manner. His talents, as an artist, are too welk known and too highly appreciated, to stand in need of any praise from me; yet I should consider myself as deficient in justice, if I did not endeavour to call the attention of the reader to the skill and ingenuity, which have been employed not only in this very important alteration, but in every contrivance that is peculiar to the instrument, which is the object of our present consideration. These microscopes can now revolve about 60° from their horizontal position; and it is easy to comprehend, that, by this valuable improvement, all errors of division may be completely done away, without any of the manifest inconveniences of the French circle of repetition; which, though a very ingenious instrument, and admirably adapted to some particular opera- tions, will, I think, never be adopted for general use in our observatories, Theplumb-line The plumb-line, a very material part of this instrument, is suspended from a small hook at the top of the tube at the left ~ hand ASTRONOMICAL CIRCLE, 205 hand of the figure. It passes through an angle, in which it résts in the same manner as the pivot of a transit instrument does on its support. At the lower end of the tube which pro- tects it, a smaller tube is fixed at right angles, which contains microscopic glasses so contrived, that the image of a luminous point, like the dise ofa planet, is formed on the plumb-line and bisected by it. Great attention should be given to the accurate bisection of this transparent point by the plumb-line at the mo- ment of observation. It is absolutely essential in instruments of this construction, to consider the observation, as consisting in two bisections at the same time: the one of the star by the mi- crometer, the other of the plumb-line-point by the plumb-line. The least negligence in either of these bisections will render the observation unsuccessful. The two strong pillars, which support the axis of the vertical ypright pillars circle, are firmly united at their bases to a.cross bar; to which and vertical also the long vertical axis is affixed, and which may be consi- rand nine xvas deted as forming one piece withthem. The stone pedestal is pedestal. “hollow, and contains a brass conical socket, firmly fastened to -the stone, and reaching almost tothe ground. This socket re- ceives.the vertical axis, and supports the whole weight of the moveable part of the instrument, which revolves on an obtuse point of the bottom ; the upper part of this vertical axis is kept steady i ina right angle, haying two springs opposite the points of contact, which press it against its bearings, and it thus turns in these four points of contact with a very pleasant and steady motion. The bar, in which the vertical axis is thus centered, is acted Adjustment of on by two adjusting screws in directions at right angles, and the vertical perfectly independent of each other. By these motions, the eT axis may be set as truly perpendicular, as by the usual method of the tripod with feet screws, which could not in this case have been employed. The frame to which this apparatus is attached, is fixed to the corners of the hexagonal stone, by the conical tubes; be- tween which and the stone, the azimuth circle (which forms one piece with the vertical axis) turns freely. The azimuth circle of two feet diameter, consists of eight conical tubes, in- serted in the vertical axis, and which are united at their ends by the circular limb; this is divided and read off exactly ina ‘similar manner to the other circle. A level 206 ' ASTROMOMICAL CIRCLE. --and of the ~ ‘A level remains constantly suspended on the horizontal axis, Aorizontal axis. which js verified in the same manner as ina transit instrument. There are forcing screws fer this purpose, which pass through the bar on which the vertical columns stand, and these by pres- sing against the long axis, produce a small change in the in- clination of the upper part of the instrument, without altering the position of the azimuth circle or its axis. The application of the plumb-line, as already described, is peculiar to the instruments made by Mr. Troughton: it regards the vertical axis rather than any other part, and is, in fact, exactly analogous to the usual verification of a zenith sector, . On the adjust-- During the period in which I was engaged in making obser- ment ef circu- vation with circular instruments, I was led to consider the ad- larinstruments ; : ; vantages and inconveniences of the usual method of adjust- ing them; and it appeared to me, that the essential part of their construction, which relates to their adjustment, was capable of being improved. In order to render the nature of the improvement, which I wish to propose, more intelligible, I ought previously to re- mark, that there are, at present in use, two modes of adjusting these instruments, which are founded on different principles. , Two methods » Inthe one, two points are taken on the limb of the circle; on onan on 2nd when these are brought into a given position, by means of the circle are a plumb-line passing over them, the microscope. or index is hehe ee made to coincide with the zero point of the divisions: by this means of ak method, the error in collimation remains constant; and if the plumb line, adjustment is by any accident deranged, it can easily be recti- and the index ee -is then brought €d, and there will be no absolute necessity for frequently re- to zero. versing the instrument; so that this method seems well adapted for large instruments, particularly if placed.on stone piers. But it is liable to this defect, that the adjustment cannot be exa- Objection. The mined at the moment of observation; and if any change should pee 4 take place in the general position of the frame work, the obser- render the ob- vation will be erroneous without the means of detection. It eee ©1T0- was probably to avoid this inconvenience, that Mr. Troughton, in most of his instruments, particularly if they were intended to move freely in azimuth, has preferred the other method. ' Or. 2. The In this case, the plumb-line is attached to one of the pillars, plumb-line be- which support the microscopes in the way above described ; and ing attached to . - Peis : nro support of it has no reference to any fixed points or divisions on the limb of ft ASTRONOMICAL CIRCEEs, 207 of the circle, but only insuresa similarity.of position in the in-the miscro- dex,‘ for each position of the instrument; and, provided that the: hoe ea. plumb-lime apparatus was free from all danger of derangement,: 4 each obser- this, would, be,,sufficient., This verification may be rendered, vation is made perbaps more intelligible,. by considering that a circular instru- gis te; ment, in whatever manner its vertical axis be placed, indicates after reversing by a double observation, the angle which the object makes with, the peseileaiyy the axis, round which the whole instrument. has revolved in eles ah passing from one position to the other. _ For let Pp be theaxis, Tx the telescope, xin one position; it is.evident, that in turn- ing the instrument half round, zy willthen be the position ¢ of the telescope; Px being equal to Py. The arc xy, which the telescope passes. through to regain ifs former position, is the quantity really given by the instrument; and if the axis Pp be vertical, half this quantity is the true zenith distance, of the object. Now the intention of Mr. Troughton’s verification is to insure a vertical position to the axis Pp. For instruments which rest on moveable pillars, and turn Objection, that freely i in azimuth, this method is much to, be preferred; but it ne PRED. is. not without a_ considerable defect:, for, if by any derange- =seih Sane ment in the plumb-line apparatus, the error in collimation. be x me mess changed, it cannot be restored with certainty to its former po- Sri cate a sition; so that sometimes a very valuable series of observations ‘anged. aay be lost, for want of a corresponding one to compare- with it... _The mode which I propose to adopt to remedy these in- conyeniences, will enable us to combine all the advantages of the two methods above described: it is extremely simple i in its principle, and easy of execution, for it merely censists in unit- ing on the same plumb-line the two principles alr eady explained, 1p Two, very fine holes. should be made in the farther limb of Union of both nn circle, and two lenses firmly fixed opposite to. them,, in Methodsin one the ‘other, which should each form an optical image of its Mantis ake correspon ing dot or hole, in the tube through which the plumb-line passes.* It will be best, if these dots are made rt exactly * As these transparent dots are intended to be bisected by the plumb-line, they must be capable of the necessary adjustments, both for distinct vision, and for placing them in an exact diameter. It may be found more convenient in practice to arrange the whole - apparatus in sliding tubes, butin whatever way the contrivance be executed, the points should ultimately be fixed as firmly as the divi- siogs of the instruments. 208 The second is most deserving of confidence. frrors of divi- sion in the tn- strument, --determinable with great cer- tainty from the stars. ASTRONOMICAL CIRCLE. exactly in a diameter, as they may then be used in two posie tions. Beneath these should be formed the image of a luminous point, according to Mr. Troughton’s present method, by an apparatus attached to the plumb-line tube; when the two pointson the circle move away, by:the necessary operation in observing, the lower point will remain stationary, and indi- cate any change of position in the whole instrument, if such should accidentally take place, and which by the other method alone would have passed unnoticed. The contrivance above described was executed for me at my request by Mr. Troughton, and is represented in the plate; but by some accident a part of the apparatus was broken in putting it together, so that I never was able to use it. As each apparatus for this adjustement is quite independent of the other, no possible inconvenience can attend their appli- cation, as either may be employed alone, at the option of the observer. But as any verification requiring many bisections is objectionable, I would in general certainly prefer Mr. Troughton’s method, and only have recourse to the other, when there was reason to suspect that some alteration had taken place to render it necessary. One more circumstance respecting the instrument remains to be noticed : when the divisions were first examined by opposite readings, 1",25 was the greatest possible error which was to be apprehended, and 0'',7 the mean error ; but in its journey it seemed to have suffered some very small derangement in its form: this was discernible both from examining the oppo- site readings; and by deducing the error of collimation by zenith stars, and comparing it with that found by an horizon- tal object, there was constantly perceived a difference of 3"! between the error of collimation deduced from y Draconis and by an horizontal object; and this quantity was very uniformly distributed through the intermediate arc. In what particular manner the observations would be affected by this derangement I willl not venture to decide, but I think it most Itkely that it-has only rendered the instrument rather less ac- curate than it was originally, as isabove stated. I have before observed the great advantage the circle possesses of showing the amount of its own errors. These mav be determined with great est by examining the errors of collimation as deduced ASTRONOMICAL CIRCLE. 209 ced from. different stars. This method is founded upon the supposition that half the difference of the two extreme quan- tities is the greatest error of division, which has in this case influenced each result in an opposite direction. For instance, let us suppose the errors of division never to exceed 2", but occasionally to amount to that quantity, on several parts of the circle ; it willthen sometimes occur that each index will give 2" too much in one position of the instrument, and 2" too fittle.in the other; there will then appear a difference of 4" in the error of collimation; but the observations in these extreme cases will not on that account .be the less to be de- pended on; on the contrary, the probability is in favour of their superior accuracy. : Nor, on the other hand, will those observations which give the mean error of collimation. deserve greater confidence than the rest, since it isevident that some of them may be, and most probably are, affected with the greatest possible errors for we suppose the most erroneous observation to arise from the greatest error of division occurring on each of the four arcs an the same sense, that is all pis or all minus; nevertheless, the observation thus erroneous, will give the mean error of collimation. By atattentive consideration of these circumstances, correc- The great ac- tions might perhaps be obtained which would somewhat dimi- mn e Pe nish the probability oferror. But it is to the principle of the cutar insiue revolving microscopes, that in the future construction of in- Ment is to be -Struments we should look for perfection., In the French circle ene of répetition, too great a sacrifice is made to the supposed microscopes. advantage of reading off a great number of observations at once. Qur best instruments are too weli constructed to stand in need of this contrivance, as the divisions ona two-feet circle are read off with precision to a single second. The errors of simple The ees of division alone are those which continued observations have no Re eee ne tendency to diminish; these, by making the microscopes errors of divi- revolve, maybe completely done away. An instrument thus 2°" constructed would be well adapted to detect small motions in the fixed stars which hitherto have escaped notice, or such as are but imperfectly known; for we cannot reasonably conclude that what is termed the proper motion of a star, is so uniform and constant, that being once determined, it will remain always the same. . Vou. XVI.—-Marcu, 1807. U x 210 Enquiry whe- ther the lichen may not afford a resource in times of fa- mine. The Iceland lichen grows in Spain, and elsewhere in southern Eu- rope, It is of little value for dye- ing. Reports of tra- vellers con- cerning itstus as food in he north. LICHENS AS FOOD, x. On the Utility of the Lichen of Iceland as Food. By Professor Proust. Abridged from a Memoir in the Journal de Physique for August, 1806. Vue Professor begins his memoir by remarking, that the severe pressure of famine, and the diseases which follow in its train, were such as, a few years ago, directed the attention of every thinking man to the means of affording subsistence to the poor, And, under this interesting head of enquiry, he asks, whether the lichens, of which numberless species cover the rocks throughout Spain, and which constitute a large part of the food of the Laplander and people of Iceland, do not promise advantages well deserving investigation. Don Mariano La Gasca has discovered, in the environs of the monastery of Harvas, the very lichen of which the Ice- landers prepare a food, which travellers affirm to be as sub- stantial as wheaten bread. This monastery is situated at a considerable elevation in the mountains which separate the province of Leon from Asturias. It is also found in great abundance in many parts of the latter province. It was before known to grow in many places of Europe, but has been prin- cipally spoken of as an article of medicine ; concerning which our author speaks in a general way, and without any marks of approbation, in the course of two pages, through which it is needless to follow him. When Mr. Proust received the lichen from La Gasca, he found reason to examine it rather as an article of food than a dyeing drug; being induced to do so by the reports of tra- vellers, collected in the Apparatus Medicaminum of hen which are the following : Von Troil Ay aN us that the Icelanders made excursions of a week or a fortnight to the districts which produce the Lichen, which they carry home and keep in sacks till the time of use, when they wash it and reduce it to flour. Olafer asserts that two measures of this powder are as nourishing as one measure of wheat flour. After soaking it in water for a day to take away its bitterness, they boil it with whey till it is LICHEN AS FOOD. is converted into jelly. They eat it either hot or cold, with an additional portion of whey or milk. * According to Benzelius, the Laplanders boil the lichen in one or two waters and throw away the decoction. They afterwards wash it in cold water and boil it in milk, after having crushed it. This soup is seasoned for use with salt. The author shows that a part of the nutriment is thrown away along with the decoction. Some Swedish botanists, who travelled in Lapland during the summer of 1788, when the north of Germany and the west of Bothnia, were afflicted with a cruel famine, subsisted upon it for a fortnight. They soaked it all night in hot water, and in the morning they boiled it with milk. Scopoli informs us ‘that, in Carniola, there is no food known which fattens animals so speedily as this lichen. Lean horses and oxen are taken to the places where it abounds, and in less than four weeks they become very hearty and fat. Q11 It is very nou- rishing to anis mals. According to Pallas, the people of the northern: part of | Asiatic Nessia support themselves upon a lichen when their other provisions fall short. After these introductory particulars our author proceeds to give the result of his observations and experiments. The lichen is cleaned by picking out the mosses and frag- ments of wood, and washing away any earth which may lie among its roots, by rubbing it with the hands under water A very short time of immefsion in cold water restores the colour and humidity of this vegetable, and more than doubles its weight, In order that the water may extract its bitterness, it is necessary to crush or divide its parts by cutting or pound- ing- In this state water. extracts, in the course of three hours, a bitter and slightly yellow juice, not absolutely disa- greeable, but very supportable when the plant is prepared by simple boiling, without maceration. The extraction of the bitter principle by cold water diminishes the weight about three parts in the hundred. Hot water takes out the bitter- ness more speedily, but at the same time extracts about an equal quantity of the nutriment. But this trifling loss is com- pensated by the speed with which the effect is produced. The bitter principle is an extractive matter, which strikes a brown with iron, sti is used for that purpose by the Icelanders. It U2 is Method of pre« paring it pre- vious to washs * ing. Cold water takes away ite Ditters ees 912, LICHEN AS FOOD. is not, however, so good as to be preerabie in the European dye-house. . but not itsnu- . Such infusions as are here mentioned would extract thé ea Princi-. most useful parts from vegetables in general, particularly gums, ; and sugars; but the lichen sustains no considerable loss, be- cause its nourishing and soluble parts are very different from Sugar, gum, or even farina. “ oh oe a One quarter of an hours boiling in water is sufficient to cook slisht bo i : : ihe ge! ihe lichen, and render it as tender for use as can be wished ; twice its at the same time that it extracts the soluble principle. After weight, the boiling, one pound of the lichen from its dry state, three pounds of the plant, fit to be served up as a vegetable in the solid state, are obtained. It is remarkable that the boiled lichen, when pressed in a cloth, to expel the superfluous ' water, recovers its first volume as readily asa sponge. So far from resembling those vegetables which have a ligneous struc- ture, which requires considerable boiling, it has the elasticity of some champinions, and eats like the very tender cartillages~ of animals. The lichen has not, however, any analogy to animal substances. When boiled The boiled lichen when dry, and preserved in that state, and dried resumes its elasticity in an instant, and becomes fit for the scalding water : i, i instantly swells table by pouring boiling water upon it. Fresh water, or sea it out, and ren- water, ave equally applicable to this object. Some persons, ders it eatable. | have eaten it at the author’s table, and knew by expe- rience what an invaluable resource fresh vegetables are in long voyages, remarked, that a provision of hoiled lichen would afford a fresh sallad, no less agreeable than advantageous to the health, under circumstances of this nature. The author thinks that this sallad, which, without any consumption. of Sea water may fresh water, is itself as fresh as if itcame out of the garden; be used. must be of advantage against the scurvy. Cold water answers the purpose here mentioned as well as hot, but is not quite so speedy ; so that the preparation of this sallad does not, in strictness, require any consumption of fuel. It isan agree- Professor P. speaks with great commendation of this vegeta- able feod. ble, when seasoned and served up under roast meat, and also asa sallad. All his friends approved of it; and the consump- tion of his kitchen was incomparably greater than that of his laboratory. He remarks, that a slight boiling gives it all the tenderness LICHEN AS FOOD. 913 tenderness it is capable of, but does not take out its bitterness, which-requires a little longer time: but he remarks, that the bitterness is not at all disagreeable; and that if its effects be aperient, as Scopoli affirms, it would agree with many constitu- tions. According to the judgment of several Americans, the boiled lichen particularly resembles the fucus, which is called luche at Lima, of which so great a consumption is made along the whole coast of Peru and Chili. As apound of lichen affords three pounds of boiled vegeta- Observation to , : : shew that it - S ’ ble, and these, when dried, are reduced to two-thirds of a SIRES I } pound, it clearly follows, that two-thirds of this food, when solid nutri- taken, consist of water. Mr. P. anticipates this as an objec- eek A) ey tion which might probably be made against its nutritious qua- great quantity lity. And to this he replies, that it is probable that water may of water ab- be among the substances upon which the digestive faculties act, 5 ghess and which, by its decomposition, may serve as food. He refers, in support of his arguments, to other articles in common use, which are liable to the same objection, such as boiled potatoes ; and he asks whether, since a dozen of the whites of eggs really contain only one ounce of dried albumen, we are authorized to conclude that a man, who should have dined upon this dozen in an omlet, had not made a solid and satisfactory meal. - The former part of the Professor’s Memoir was confined to Chemical exa- the domestic uses of the lichen. In his second part, he heats mination of the of its chemical examination. Many of our domestic plants are unfit to form a component affords a part of soups and other liquid foods; but the lichen is emi- nourishing rently qualified for this use, its decoction being charged with MST t° SoHPS nutritious matter, This soluble substance might, at first con- sideration, be classed with the gums; but it differs so conside- rably from these that the author thinks it forms a particular species, entitled to attentive examination. It was. before observed that the lichen loses one-third of its Statement of” weight by boiling. But more strictly speaking, he informs us, 2 ate, that one hundred parts of the lichen grossly powdered, afford, rated by water. by infusion in co!d water, three parts of the extractive bitter principle; and after treatment with boiling water, the undis- solved residue amounts to sixty-four parts when dried. Con- sequently the quintal of dry lichen censists of 2 D3 Fleshy 214 LICHENS AS FOOD. Fleshy, or pulpy part . . . 64 GE Dare eo ie eal oe ae Diskgow ph part.) $6 amavis Limon ee / 100 . err ot The thirty-three parts consist of a nutritious matter, not bein ‘wa, Soluble in cold water. The bitter principle is therefore sepa- ter but not in rable from the rest by cold infusion of the pounded plant; and cold. ~ tneleeianders follow a more saving method than the Laplanders, _ who throw away the decoction. Experimentfor The Professor boiled the farina of washed lichen with milk, eee ee of Until it appeared to be sufficiently cooked; and this, when sea- the Icelanders soned with pepper and salt, was estitled to a comparison with with lichen. —_yice, or millet, boiled in milk. Ithas a greenish colour, and is a little acid: but not more incompatible with habitual use among the poor than many other country foods, which those who are not accustomed to them, would by no means consider as dainties. Another dish was made by seasoning the preceding milk and lichen with yolk of egg and sugar. It was much more plea- sant, but certainly not superior in its nutritious qualities, Great strength The decoction of this plant is of a light yellow color, and i itsgalatinous has a slightly bitter taste. Its gelatinous quality is so predo- ecotion. ; : ie minant that one pound of dry lichen affords, by boiling, about eight pounds of liquid, whichcongeals by cooling. And as no more than one-third of the weight of the lichen enters into the decoction, the jelly itself is formed of one part of this peculiar gum and twenty-three parts of water. Professor P. considers this as the only vegetable matter capable of rendering so. large. a proportion of water gelatinous. ~ - The waterse- The jelly of lichen exhibits some peculiar properties. When Bigs by stan- left to stand for some days, the water is seen to separate at the edges, however cool the place may be where it is kept. If the plate be inclined in different directions, the jelly breaks with a facility much greater than is seen in animal jellies, or even those of fruits; and in the cracks the quantity of water increases, as if there were but little attraction: between that flurd and the jelly. Tt is not at all During the boiling of the jelly this principle forms, at seid. the surface, transparent bulbs, which are renewed con- - tinually when skimmed off; but these bulbs, when again Ai added ‘LICHENS AS FOOD. 915 added to the fluid, do not dissolve unless it be boiling; a fact which confirms the opinion that this species of mucilage is less soluble than any with which we are acquainted in the vegetable kingdom. Unlike every one of the known gums or mucilages, this jelly, when concentrated, 1s not viscid, either cold or hot, and it may therefore be-doubted whether it would be useful in the arts, unless for calico printing ; a point which | deserves to be examined*. From this want of viscidity it happens that the jelly, when dried upon plates, divides into transparent angular and brittle fragments of a deep red colour. The animal or vegetable jellies differ extremely from it in this respect, because the viscidity, which connects their\parts, pres vents their separating while drying. Jf the dried gum of the lichen be thrown into hot or cold Habitade of thé water it does not dissolve, but it softens and swells up, with» dried gum with out becoming viscid or tenacious ; but it deposits very speedily et all its extractive matter, and consequently its bitterness. This property affords a means of purifying it m case it should heres after be found of service in the arts. The infusion of galls, which has no action upon the known The green is gums, instantly precipitates the jelly of the lichen, and affords ae aa a white mass, as with animal jellies; but there is this diffe- precipitate i rence, that the new combination dissolves in hot water, and Soluble in hot, separates by cooling. In this fact we have a character of the ili mucilage of lichen, which seems to assimulate it with that of animal matters; but the following experiments decide other- Wise. The gum of lichen, heated ina retort, is destroyed without Products by being softened. Like gum arabic it leaves only 23 or 24 ey tsa hundredths of charcoal. Its products do not differ from those of gum or starch; that is to say, they consist in water and vinegar of the same odour; but the oil appeared to be much more abundant. Potash separates from this vinegar only a few atoms of ammonia. The nitric acid readily converts it into very white oxalic yiticacid Bust acid, leaving no tallow, or yellow bitter principle, in the duces the axa- is late. residue, * The jelly of lichens was examined eight or nine years ago by Lord Dundonald, and offered for this purpose to the calico printers, wm 22 216 Habitude with potash, Blane monge, &C, Whether the gummy matter would afford starch by fer- mentation. LICHENS AS FOOD. residue. Lichen, boiled and dried, affords no more than 24 or 22 hundredth parts of coal. . The nitric acid dissolves the boiled lichen with great faci- lity; an effect which is not commonly seen with the ligneous vegetables. The product is oxalic acid and oxalate of lime, augmented, as seemed to the professor, by a foreign earth. The residue contains the yellow bitter principle in a very- small quantity. Potash converts boiled lichen into a gelatinous pulp, similar to that which is afforded by farina in like circumstances. These facts appear to show, that the fleshy part of this plant is an indurated gum, less oxigenated perhaps than those which are soluble. The jelly of lichen may be used as food. The author made a very good blanc-manger, by adding a small quantity of flour, with sugar, and afterwards some milk, or emulsion of almonds. The author here makes a remark con- cerning the necessity of condiments or seasoning, to give flavour to this jelly; and takes notice, that the same necessity exists with regard to all gelatinous foods, whether animal or vegetable. Starch, as he remarks, is the basis of bread, and glue of soup; neither of which would be acceptable to the palate, or supportable by the stomach, without some etimu- lating ingredients to season them. . The analogy of lichen to starch, in its want of solubility in cold water, is opposed by the difference, that it has no adhesion when dissolved; but he thinks it would be interesting to. treat the lichen by an appro- priate fermentation, to see whether this ferment would not separate it likestarch. He likewise suggests the probable ad- vantages to be derived from an examination of the several spe- cies of the vast family of the lichens, XI. On GAME COCKS. 217 Onthe breeding and feeding Game Cocks. From Sir Joun — Sincratr’s Collection of papers on Atheletic Exercises.* Questions proposed. }. Tous the superiority of game cocks depend upon parentage of parentage ? Which is of most importance, the male or the 84me cocks. female? Is it ofany consequence that the cock should arrive rather gradually at maturity? Is there a great difference, in point of strength and constitution, in game cocks of the same _ parentage’ Do you prefer great or small bones ? 2. When do you begin to feed the young cocks ? What diet Feeding. and drink do you give them, and what is the process by which they are brought to the greatest possible height of strength and spirit ? 3. When the game cocks are thus trained, how long do the Longevity. effects thereof last? Are they temporary or permanent? Do —game cocks thus trained live shorter or longer than others of the same species ? 7 4. What drugs are given to fighting cocks immediately Medicines. before the main begins? Is it not usual, by giving them saffron, (or some drug, which has the same effect with opium, as used among the Janisaries, or brandy among the French soldiery), to excite an unnatural and short-lived courage ? What are the effects of such drugs? and how do they manage the feeding up to this point, so as to take advantage of this momentary excitement ? The * The moral effect of cock-fighting is, no doubt, a subject deserv- ing to be considered; but concerning this, as the Selector of a philosophical article, I wish to be supposed to advance no Opinion at present.—N, 218 Information respecting breeding, train- ing, aud ma- nagement of game cocks. GAME COCKS. The following interesting Letter teas received from a Clergy- man. West Ham, March 28th, 1805. Dear Sir, I perceive that only on one part of your well directed Queries Tam able to give you satisfaction, and that is, on what you would least expect from a D. D. and the sober vicar of a country parish: the subject to which I allude is cock-fighting. At the period of my childhood, when IJ ran wild, from ten to fifteen, I was a great cock-fignter, and though it is many years ago, I find my memory perfectly competent to even the minute nar- ration of every fact. . But before I proceed, J will intrude a remark or two upon your preliminary observations. In all the theoretical part I completely coincide: indeed I was pleased to find so much harmony between your sentiments and those I lately transmitted to you, without the possibility of any previous concert between us, I do not even question your facts, but seem to differ a little with respect to some of the inferences. With respect to the South Sea islanders, and the difference between them and the English sailors, I doubt whether there was any superiority in the training of the former, which gave them the advantage. An English sailor is, perhaps the very perfection of agility in his own way*. ldo not know that thé human, powers can 2 g° * An officer of a frigate who had’been at the Sandwich Islands has declared, that our sailors stood no chance in boxing with the’ natives, who fight precisely in the English manner. A quarter-master, a very stout man, and a skilful boxer, indignant at seeing his compa- nions knocked about with so little ceremony, determined to try 2 round or two with one of the stoutest of the natives, although stongly dissuaded from the attempt by his officers. The blood of the native islander being warmed by the opposition ofa few minutes, he broke through all the guards of his antagonist, seized him by the thigh and shoulder, threw him up, and held him with extended arms over his head, for a minute, in token of triumph, and then dashed him on the deck with such violence as to fracture his skull. The gentlemen ad- ded, that he never saw men apparently possessed of such muscular strength, Our stoutest sailors appeared mere shrimps, compared with them. Their mode of life, constantly in vigorous action in the open air, and undebilated by the use of stimulating food or drink, may be considered asa perpetual state of training. Sir J..S. \ GAME COCKS. - MPS go beyond it, in some instances, that I have seen with nay Information own eyes; yet an English sailor, though he could probably Sopaead ae climb a rope better, could not dance upon one, as I have seen ing and ma- the people at Sadler’s Wells. The superiority, therefore, of ya eee ye: the South Sea indians in wrestling, boxing, and rowing, I at- ST ene tribute merely {o practice. It was also in their own voay that Cooke’s sailors contended with them. In a fair boxing-match, Ihave not a dou$t but Mendoza or Humphries would have triumphed over atleast twenty of themin succession. By the way, from what I have learned of amateurs, respecting these pugilists, no persons can lead more dissolute lives, except in the article of exercise, With this exception, that those among them who drink moderately (and moderation with them is free-living among other people) are the strongest. Ona subject where 1 am more at home, my observations will lead to the conclusion, that the simplest mode of living is the most conducive to bodily health and strength. Though very young when I pursued cock-fighting, from nice observation, which enabled me to judge of a good cock, and from a rational mode which I fell into of treating them, I hardly ever lost a battle, even against odds ; but I will pursue the subject in your own order. ’ , Ist, There is not a doubt but that the sterling courage of an English game cock depends upon parentage. It is a maxim in the cockpit, that if a cock has, what they call a spice ofthe dunghill, though ever so remote, when he is galled by the spur hewillrun, .I remember seeing a most famous cock, about eight years old, and who had in his time won forty battles, run at the last, when severely galled. A dunghill however fights harder for a round or two than a genuine game, whose courage is ofa more temperate cast, and this very famous cock was aninstance, who generally killed his antagonist with a stroke or two. A true game-cock is, however, so well known by his marks, that sportsmen will rarely be mistaken.. My mother has bought a clutch of chickens at the door, and Ehave selected from them one or two by my eye, which have proved incomparable. One of these chickens gained ten battles in one day, the last against on old cock, double his weight, and after mine, which was but a stag (that is one year old) had been cut down to the ground, and was counting out, that is, given up for dead. - Large 220 Information respecting breeding, train- ing, and ma- nagement of g2me cocks. GAME COCKS. Large bones are always preferred in cocks, and it is ari ex- cellence to stand high on their legs, for this gives them an ad- vantage over those of a squat make. 2d. The best manner of bringing up game cocks, while young, is in a farm yard, in as free'an air, and as much agreea- ble to nature as possible. About three weeks ora month before’ they were to fight, I put them up, as it is called, or put them in a dark close penn, about two feet square. They are debilitated by being suffered to run among the penns, and their muscles are not Gon The first week I fed them upon barley, that 1s accounted a scouring food, but it answered best at the first period of their confine- ment. I fed them three times a day by measure, I cannot now ascertain the quantity, giving them very little water each time ; and oncea day, or once in two days, took them out to spar, or fight a few strokes with one another, with their spurs muffled. The second weck, and during the most of the remainder of their confinement, I fed them on pure wheat, according to the same measure, having always regard to the state and regularity’ of their bowels, and giving a little barley, if they appeared cos- tive. During the last three or four days I gave them white bread, according to the same measure, though I do not think bread was any better than wheat; and some that I fed en- tixely on wheat, afier the first week seemed to do quite as — as those which had bread. This was:the whole of the process which I employed. I could always tell, by the firmness of the breast, whether ‘my cocks were in order. I found them by farthe strongest, without’ diminishing their activity, when they were plump but firm, without fat; and I question but, they would have eaten as fitie, and had nearly as much firm muscular flesh as a fowl from a’ London poulterer’s. With this mode of management a cocks were four out of five, at least, successful. 3d... The training of the cocks, in the manner I have des- cribed, produces only a temporary effect; nor does it in the least seem to shorten their lives. I have known them live and fight at ten years old; whereas the poultry in my yard at pre- sent seldom reach that period. 4. Ihave heard of saffron and other drugs being given to cocks; but mine, which were plainly fed, always beat them. Opium. or mney may be necessary to Janisaries or French- men, GAME COCKS. 921 men, but no dram is necessary to excite the courage of a true Information game cock, ora British soldier. Sch carota The.Rev. Mr. P— isa native of Yorkshire, and may jing andma- possibly be able to give you some information on the breeding nagement of of horses, and the training of jockies. At all events, an appli--8*™° Racks cation to him, mentioning my name, can do no. harm, and you will find him an obli liging and intelligent man. He lately: sent me a letter on the culture of spring wheat, which I sent to the board. I am, dear Sir, With great respect, &c. -P. ST had forgotten one fact worthy of notice; when a cock had been fought so hard that he is even apparenily dead, I have known himsrestored to life by covering him up, all but his head, in a warm horse dunghill, or a common hot-bed in a garden, On this you may depend, and I have no doubt that the cocks I speak of would have died but for this treatment. A short Account of the Manners in which Game Cocks are bred up and trained for fighting. By an experienced Feeder. _ Itis a general principle in breeding cocks, that large bones are not desirable, but that large muscles are. The thigh should be long, with as much muscle as possible. The legs should be ofa medium length, and not short like the Bantam aly They cannot stand too high if the thighs arelong. They should be round bodied and not deep (caille d) Seite A smail head is _ of essential importance, and it is a good sign to be hazle-eyed with black eye-brows. The black breasted red cocks in gene ral stand the penn better than any other sort. Parentage is certainly of great consequence, though there is often a very material De ecee between cocks hatched at the same time and from the same parents. The blood principally comes from the female. The likeness or outward shape from. the male. Thehens of the game breed are very spirited and even violent, and will not suffer a strange cock to have any connection with them. Breeding cocks in and in, or stale breed as it is called (that is keeping uniformly the same stock) isa very bad system. It reduces their size, and takes away their vigour 40 so greata degree, 2 292 GAME COCKS. Information degree, that they can hardly propagate their species, and the’ ti te a same is remarked in horses. If game cocks are bred in and in, ing, and ma- they will stand to be killed erated flinching, but they have moran ent not spirit or activity enough to attack their foes with any effect. If intended for fighting, they should never be crossed with dunghill fowls, for any taint of that blood makes them unfit for along contest. The best plan is, occasionally to cross with some of the game breed of a different stock. It is of great importance to have cocks inwardly clean, that is free from fat, for on that depends their being in wind. Neither race horses nor game cocks that are inward!y fat can be in wind. To give them a good constitution, it is better to keep them as much as possible in the open air, on a grass-plot, and with a gravel walk to go to. The more gravelly the soil on which they are kept the better. Yards are dangerous, more especially where horses are physicked, as the cocks may pick up what may do them mischief. Cleanliness is particularly neces- sary. When young, the chickens are kept with the hen under a hutch, and fed with oat groats; when they become older they get unhulled barley, which is reckoned more nourishing than oats. When they are put up to fight they are kept in small penns and fed for three or four days withthe very best barley. For drink they get about a gill and a half of water per day, of as soft a quality as possible, and with a little toasted bread put into it to make it still softer. During the remainder of their stay in the penns, they are fed on one third wheat and two thirds barley, which is a nourishing diet, without being too costive. They are fed twice a-day, early in the morning, and at eight at night. Before being fed the second time, the crop is examined to see that it is quite empty and the food di- gested. They ought not to have before they are put into the. penns, above three or four hens with them, and none after. | About four or five days before fighting they are physicked , The best medicine is about halfa table-spoonful of cream of tar- tar made up with butter into a pill. This they can easily be made to take. The object is only to give them only two or three loose stools, which lightens them, and makes their flesh afterwards firmer. The day they are physicked they get no- thing but a little warm water. Next morning they are put again on their hard feed of one-third wheat and ‘we thats bar- ley, and in the evening of that day they get a hot meal, consist~ é ing VEGETABLE FIBRES. 293 ing of wheat bread and milk, with a little white sugar candy. Information More than one meal of that sort would make them heavy or ice -aerne lumpy. In the summer season, after being physicked, they ing, and win get air-the second.day, but in the winter they ought to be kept nampa warm, without being at the same time too hot. Rane tes Brandy, or any heating drug on the day of fighting, does more harm than good, They may get, however, just before they set to, a few barley corns, with a little real sherry Wine. ~- A cock’s first battle is his best, and a cock first penned, of equal goodness, will beat a double penned one. — Game cocks live fully as long as common fowls, . In some cases they have lasted above fourteen years, and as sound as the first day. They are so hardy that they can be reared in the winter time much better than the dunghill sort. The cross between a game cock and a dunghill hen is excellent eating either as chickens or fowls. XII. Observations on the Culture, Properties, and comparative Strength of Hemp, and other vegetable Fibres, the Growth of the East Indies. By Dr.Wititam Roxsurca *, ! © (Continued from Page 47 of our XItk Volume.) O prove the durability of the various materials formerly Course of exe mentioned, I had recourse to maceration in fresh water, Perimenty during the hot season. The result of these trials will be found in the following table, which, in a great measure, cor- _Tesponds with the former, showing the comparative strength ‘Of the various cords mentioned therein, by weights suspended by four feet lengths of them. ‘The first three columns on the left, have been explained in the first part of these observations; in this the largest cord only of each sort has been inserted. The three last on the same side express the average weight at which each sort of cord broke, after having been kept at the bottom of muddy, half putrid, stagnant pond water, from the 27th of February to the 22d of June, 1801. From * From the Memoirs of the Society of Arts, 1806. 994 VEGETABLE FIBRES, Average weight at which each sort of cord broke. d After 116 days macera- ete t a: fic. White-/Tanned.]| Tarred.J White. Tanned.| Tarred. Materials, or Names of the Plants which yielded them. 105 — — — {Rotten 74 | 139 45 A {Rotten ON ete i itn gh a ce 1 Hemp from England . 2 Ditto growth o India . 3 Coir: 2 \hsyes he Bog: eee ‘ § Robinia cannabina, ripe i 6 The same cut while blossoming ..... ; 88 | 101 84 40 56 65 46 61 48 Rotten] 68 45 7 Crotalaria juncea ....J 68] 69 60 |Rotten| 51 65 8 Corchorus olitorius —| — — — _ — 9 Corchorus capsularis 67} — — 50 — — 10 Flax, growth of India. 4 39 | — — jRotten| — — 11 Agave Americana . 110 | 79 | 78 |Rotten|Rotten| 152 12 Aletris nervosus .....% 13 Theobroma Augusta Linn. 14 Theobroma guazuma, Hort; Cliff. i 15 Hibiscus tiltaceus ..... 16 Hibiscus Manihot’.... 17 Hibiscus mutabilis .. . 18 Hibiscus, from Cape of Good Hope.... - 19 ae bo) — {Rotten| — — 20 The same, but diffe- Sey ami des of Rotten)! see a rently prepared ... . 21 Sterculia villosa .... | 53] — a 30 pr a : —- OES e East India Stagnant fresh water, in a rather putrid state, during the series A hot months of March, April, May, and June, in Bengal, than.European, must be as severe a trial for vegetable fibres, as can be well found in any country. Iam exceedingly glad to find that, in general, the fibres of our East India plants stood the test infi- italy better than hemp from England, or of hemp or flax the growth of Bengal. Tar preserves Tar appears in general to be a better preservative than tan them. during the immesrion, though I was formerly inclined to think otherwise.'| The powers of No. 4, to resist decay, correspond with what the Dutch historian Rumphius says of it in his Her- barium Z VEGETABLE FIBRES. 295 barium Amboynense. Nos. 7, 8, 9, and 13, 14, retained their strength surprisingly. No. 15, (the bark with which the inhabitants of the South Sea islands make lines), gained ‘considerably in power in its tarred state. In the former part of these observations it was remarked, Additional that numerous plants, exclusive of those which yield hemp and a ey koe flax, were productive of fibres apparently well qualified for the same useful purposes; and these several sorts are pointed ott, - some of which had been long and’ well known to the natives of Asia: others appeared to me to be unknown to them. Since the date of that paper, my researches have brought to light several additional objects of the same nature, and added con- siderably to the imperfect knowledge I then had of others. At the close of my first experiments (vol. xxii. page 395-6) men- tion is made of the strength of sun cords being greatly ins creased while thoroughly wet with fresh water. From 100 to 200 additional experiments have been made since ‘that time, to illustrate this interesting fact, the result of which will be found in the two last columns of the annexed table. The cords now employed were made of three single yarns ; How fabri- and, as formerly, by no means so equally spun, or laid, as “ted. might have been done by an expert European artist : nor must their strength be compared with those of the same material in the former table, because the cords are now made considerably stouter, and the yarns are, in general, better laid, on account of their being thicker; for I suspect that the smallness of the lines employed in the former trials rendered them somewhat less accurate than the present. ‘Vor. XVI.—Marcu, 1807. ‘el Com- VEGETABLE FIBRES, Comparative Statement of the Strength of the various Materials employed in these Experiments, both dry and wet, by Weights suspended by Four Feet Lengths of the Cords. AO SY NT SS raft ty heath aa eee Z0™ /eee eis 26 |-ws§ |.o 54 . a x ee = g 2 | Se 45) Names of the Plants, or Materials |= 6 3 |B os | ¢ 3 used, and brief Remarks thereon. to's be cae ¥ bp zg e ‘a i) o a [o) i 5 SS5 1/226) 28F0 the tenperature of 300°, it lost 1-4th of its weight. Between hice 400° and 500°, it smoked, and was charred, emitting,the usual -» vapour of burning peat. When heated to. redness, in close _ wessels, it left a very briliie charcoal, amounting to 1-4th of its weight. When burnt in the open air, it left a quantity of yel- lowish grey ashes, containing iron, amounting to 1-100th part of the peat. Good peat is much denser, not so easily decomposed, and approaches more closely to coal. With this peat cut into smail fragments, I sometimes filled Experiments an unglazed earthen retort, sometimes a cast-iron bottle, and nar oe ao then exposed these vessels respectiv ely to a degree of heat flammable gas ~ which was purposely varied in the different processes. Some- ies Nee times the peat was kept for a considerable time at.a tempera- ture not exceeding. 500°; and when all gas had ceased to come over, it was raised toa red heat. Sometimes it was placed at once in a strong red heat, and sometimes it was never allowed X 2 to 244 Experiments and observae tions on the in- INFLAMMABLE GAS. to become red during the whole process. These variations ‘were intended to ascertain how far the nature of the gas depended flammable gas upon the temperature. But the results were not quite satis- : irom peat, factory. Sometimes the gas was the same, though the heat differed; and sometimes the gas varied, though all the cireum- stances of the process were as exactly as possible the same. The differences I am disposed to ascribe to variations in the properties. of the peat employed. The gas began to come over very speedily. At first it was mixed with much carbonic acid; but the proportion of this gas diminished as the process advanced, though in one instance only it disappeared com~ pletely. The quantity of gas obtained from a given bulk of peat was much smaller than what is yielded by the same bulk of wood or pit-coal, owing probably to the great difference of weight between them. | ; I never succeeded in procuring the gas perfectly pure, as, besides the carbonic acid already mentioned, it always con- tained a portion of common air, var ying from 1-8th to 1 -4th of the mixture, according to the process. It was always greatest when the cast-iron bottles were used, and least with the stone-ware retorts; owing partly to the smaller size of the former, which did not allow me to throw away so great a proportion of the gas which first came over. The presence of common air cannot well be accounted for on any other suppo- sition, than that the vessels were not altogether air-tight; for the tubes which conveyed the gas to the water-trough were very well filled. The stone-ware retorts are known already ‘not to be impervions to air. To remove the carbonic acid, I at first washed the gas in a large quantity of water; but finding afterwards that a portion of carbonic acid still remaimed, notwithstanding this process, I removed it, by washing the gas in lime-water. To ascertain the proportion of common air contained in the gas, 1 empleyed nitrous gas, according to the method of Mr, | Dalton, afier having convinced myself of the accuracy of that method by repeated experiments. Into a long narrow tube, graduated to 100ths of a cubic inch, a portion of the gas to be examined, 1s introdnced, and its bulk being neted exactly, a determinate quantity of nitrous gas, previouisly measured in a similar tube, is let up to it. If any common air be present, the bulk of the two gases gradually diminishes. The diminu- tion INFLAMMABLE GAS. 245 tion of bulk, whatever it may be, is noted down, and muiti- Experiments plied by 0.36842: ihe product is FIRST SECOND COMBUSTION COMBUSTION. Bs ert gee 2s 2-13 | 3 ‘6S 1S |28).s4. 1 °SE (| SBped hss gles ws a a ‘Z g 7) s SA tei ts nn uy 1 te Po 2.c).9 9.) Bee Pig) 8 BL Fo | Be edt Bevea se) a9 | oho | eo 2 sliaedl| Soy Ser BELLAS || Seen) ae] Se3l sen) a i { neh cd ee) ZO, 30) 40 Aztellsoco |ZslaztzlS29!] a8 ! a|\ 1 30 | S |NoCombustion | :. a| 2 30 | 12 | 35 |. 32 12 32 | 26 20 | 43 a| 3 30 | 16 | 33 | 28 16 | 34] 28.5} 21 | 38 a| 4| 30 | 20 |37.5| 32 2 |36| 27 | 31 | 46 a| 5) 30 | 24/37] 30 || 24 42 | $2 129" 49 al 6 30128}36| 265|| 28 | 46! 38 | 36 1 46 al’7 30 | 32 | 39 | 27 | 32 | 59'|. 59° | 44 {47 (Neo 2d ombus, al 8 30 | 36 41 | 31 | . | 26 | 43 ae 219 20 | 40 | 38 | 28 | | a7 | 34 b 10 20 | 60 | 57 | 43.5 | | | 31 | 46 b|11 20/80] 75 | 61 (i 48 | 46 _b\12 20 | 80 77 | 62 | | 86. | 65 b\13 20 | 80 | 77 | 64 hie 49 | 58 ee ——— — eS OOO - en ee eee PLE SS ese b\14 20 loo | 97 | 83 1h & | 62! | 64 252 INFLAMMABLE GAS. ‘ Experiments | But before we can form any correct idea of the result of and observa- tions on thein- these experiments, it will be necessary to state the exact quan- flammable gas tities of pure inflammable gas, of pure oxygen and azote pre- from peat. sent th cach mixture, and likewise to note the composition of _ the residuary gas, as indicated by the analysis. All this done in the succeeding table. - FIRST COMBUSTION. |SsECOND COMBUSTION | || Addition. Z) |. Residue. | , | | | S | 2] 26.4) 7-71) 7.89) 35 6.96, 5.04| 32 6 — | ee] Oe wee, 6-72} 34 5-5) 423]16,29| 7-98 1-10}12.93)1 1-97 cere een nr ee ee mmm mm me Ys fy | | ee | (ee | enn me i} : | 4.42)19.65| 2:93 lone (ameeeeemmeeece) neuen Temeaiiiitensse? Geeta iottemeseeed | ee TWA Gees WES Coe 15.92:10.08} 42 | 10 | 6:63/23-01] 2-36 eee ee | ee | |] ee 6| 26.4416.99114.6:1 36 | 9.5 "a 26-4 19.31]16.29| 39 | 12 [ 2.10|16-29] 8.61 116.24111-76] 46 | 8 :10.31/26.47| 1.22 26-4}21-63|17-97) 41 | 10 5-16)17-97] 7.87 ee | ee ee ees | 9} 17.6)19-70|22.70| 38 es | ne | eres | en | ee ee | ny 4.05122.70}) 1-25 startenddssteer tise =a rth sine” ate arieaoassa 7 So ae Teer Fie ga rr aa Arran Pani tr i cee i Mea tee 5 nt ne EY RE eS: oni o Peeps doe ea| se 2 nw n > an A ra) ae a [s) s Oa] UR vo oao]-.= . oa) = Oy Te) me. 35 ec [=I SE oc = ° zo} as|2e[eeis2! &| 2/26/22! 2) 318, 5 ont or 4 Ofb}/ORLon] SG = S | ° DQ, aha | = n [Gq 2 J ° oO Lal Day Oo & s 2alaalaat{molosi 6 | ¢imallOs| Oo] 4 180 1s These INFLAMMABLE GAS. 953 These experiments are of two kinds, each of which ought to Experiments be considered separately. In the first five the oxygen was ane. ope ° applied in sma!l doses, and the gas underwent two successive fammable gas combustions. In the last eight, the proportion of oxygen was from pca‘e greater, and one combustion only took place. By inspecting the first five experiments, it will appear that the inflammable gas ‘was never entirely burned, but the residue di- minished continually as the proportion of oxygen increased, and in the last of the list of them, did not exceed 1-22d part of ‘the whole. If we examine the residual gas after the first com- bustion, scarcely any oxygen will be found in it: indeed, I could detect none at all, except when the proportion of oxygen approached that which limited the combustion toa single de- tonation. By subtracting the residual gas and the residual oxygen, after the second combustion, from the original quan- tities present, and by supposing the whole oxygen to disappear in the first combustion, we obtain the following table of the relative quantities of gas and oxygen consumed, and af carbo- nic acid formed, in these different experiments. FIRST COMBUSTION. SECOND COMBUSTION. Oxygen Carbonic Oxygen |Carbonic Gascon-jconsum-jacid Gas__||Gascon-|consum-|acid Gas sumed. fed. formed. sumed. Jed formed, @| 2.29 eT’ 3 12.14 | 5.86 Pipe | site | 317.97 | 10.03] 5 {10.45 | 5.05 5.5 ea 5.65 | 12.95 55 |782\718] 9 | ; 6\14.51 1699 9.5 {I10.67 | 5.93 aie aa 795 | 12. 35 | 6 11.16 | 6.26 v7 Average. a 100 | put 75.48 || 100 55.19 69 Average percent. From this table, it appears that the proportion of oxygen which disappeared by the first detonation, was much greater, compared with the inflammable gas consumed, than in the second combustion. The asia. of the first combustions gives 155 254 Experiments and observa- tions on the in- flammable gas from Peat. INFLAMMABLE GAS. 155 measures of oxygen to 100 of the gas, while the average cf the second gives us only 55 measures of the oxygen to 100 of the gas. In the first, the oxygen consumed was one half greater, and in the second, one half less, than the inflammable gas. The first detonation was always louder than the second, and accompanied bya white flame, while, in the second de- ~ tonation, the gas always burns with a blue flame. The dimi- inutions of bulk are always greater after the second detonation than after the first. {f we examine the individual experiments, we shall find that the proportion of oxygen consumed by the: first detonation, is a maximum, when the smallest quantity of oxygen present is the smallest possible, and that it gradually diminishes as we “increase the dose of oxygen. Thus, in the first experiment, of all, the oxygen consumed by the first combustion was to the ‘ gas consumed as 338:100; whereas, in the last experiment, it was only as 117: 100. In the second combustion, on the contrary, the proportion of oxygen consumed rather increases with the cose. In the first experiment of all, it is not quite equal to half the gas, while, in the last, it is raat more than half the inflammable gas consumed. If we consider all these circumstances, it will appear ex- tremely probable that the effect of the first combustion is two- —_ fold: that one portion of the gas is burnt, while another com- bines with oxygen without undergoing combustion, and forms either carbonic acid, or some other inflammable gas still un- ‘known. .The portion of this new gas formed, diminishes with _ the doses of oxygen, because the proportion of gas completely burnt increases. It was doubtless the’ formation of this new gas, in variable proportions, according to the dose of air em- ployed, that occasioned the variations in the result when the experiments were made with common air. As the whole quantity of inflammable gas was never con- sumed in any one of the experiments in which the double de- tonation was employed, and as the residual gas most probably consists, at least in part, of the new inflammable gas formed during the experimeuts, it is obvious that we cannot depend upon these trials for determining correctly the proportion of oxygen which the gas from peat consumes. The average of the whole of them nielves us 105.22 measures of oxygen as the. proportion INFLAMMABLE GAS. 255 proportion consumed by 100 measures of the gas. But, for Experiments _ the reason assigned, we must consider this quantity as rather and observa- ee tions on the in- EXCESSIVE. flammable gas As to the carbonic’ acid gas’ formed, we cannot draw any from peat. inference from the quantities obtained in these experiments, be- cause they were made over water; for that liquid always ab- sorbs a portion of this gas. The portion absorbed is variable, though in general it bears some relation. to the violence of the detonation and the diminution of bulk prodaced by it—being always greatest when the diminution of bulk is greatest. But the real quantity of carbonic acid gas formed, can only be ascertained by repeating the experiments over mercury. This, in the present case, was not done, because I considered all the experiments with the double detonation as incapable of deter- mining the objects which I wanted to ascertain. From the eight experiments in which such proportions of oxygen were employed, as consumed the greatest part of the gas, by a single combustion, we deduce the following table. Diminution of bulk Measures |Measures (Carbonic |suppposing of Gas con-jof Oxygen ‘acid Gas_ the Carbo- ’ sumed. consumed. |formed. nic acid re- | moved. Diliiat® dp Ba21. lad Zo vaahandh 001 | 18.53 | 16.47 | Io 35 | 16.35 |1! 15.65 10 roeerg (emer cere Treo Sad SERRSSSEEREEEnTTROREEEEEEOEEEaeeee 17.60 18.80 | 13.5 36.5.5: 7 emcees lemme <> = eee eee ee 1760 “TASER ee 29] —l—— | SG hikes Wie Gallic GAN “hi RRs eae cae Ceara 17,804} e9298) 415~<|--98--~ 17.36 | 18.64 | 13 Pees te | a oe ee ee ee 5 An60 fp boat | oe 17.41 , 13.08 100 =| :«99.20 |! 74°53 { ¥ ‘Average. SS lAverage percent. In 256 Experiments and observa- tions on the ine INFLAMMABLE GAS. In these experiments it deserves attention, that, after the proportion of oxygen employed exceeded a little that of the flammable gas inflammable gas, there remained only a small portion of resi- from peat. dual gas after the detonation, and that the whole of the inflam- mable gas was consumed when the oxygen was to the gas as 5:3, or in still greater proportions. It deserves particular attention, that, in four of these expe- riments, the diminution of bulk is somewhat greater than can be accounted for by the quantity of inflammable gas and oxy- gen consumed. This small difference I ascribed, at first, to errors which had been committed in making the experiments. But after repeating each of them over again three or four times, with every possible precaution, the difference still continued as at first. Iam disposed, therefore, to ascribe it to a small portion of the azote which was present, having com- bined with oxygen, and having formed nitric acid. We know that this happens when hydrogen, diluted with azote, is burnt with an excess ofoxygen. The quantity is extremely small, and cannot materially affect the results: the only exception is the eleventh experiment, which does not correspond very well with the rest. The average of all these experiments gives us nearly 100 measures of oxygen gas consumed by 100 measures of inflammable gas, a proportion which cannot deviate far from the truth. The proportion of carbonic acid formed by the combustion of 100 measures of gas, is only 74.5 measures, But as the experiments were made over water, this proportion is rather too small. On repeating some of them over mercury, I obtained 80.5 measures of carbonic acid gas from 100 mea- sures of inflammable gas consumed. These ss a then gave us the following proportions. Oxygen |Diminution|Carbonic consumed. jof bulk. cid formed 80 120 100 10. As the small portions of azote which disappeared in these experiments occasioned some ambignity, I prepared some pure gas from the hyperoxymuriate of pot-ash. It was composed of 95.5 oxygen A.5 azote 100.0 . Having INFLAMMABLE GAS. 957 Having exhausted my whole stock of gas from peat, I pre- Experiments pared an additional quantity, which, after being freed from car- mie ee . ° 10ons on the 1n- konic acid, was composed of Garimndbte ik 77 inflammable gas from peat. 23 common air ———— ae 100 Its specific gravity was 0.8516, which gives us, for the specific gravity of the pure inflammable part, 0.8072. This gas, of course, is a little lighter than that used in the preceding expe- riments. But the difference does not amount to 4 per cent. one handred cubic inches of it, at 60°, weigh 25.02 grains. _ The following table exhibits a view of the experiments made with this gas and the pure oxygen. ‘Residue |Ditto,: Nitrous | Measures} Measures'after washed jgasadded'Bulk of of Gas. Jof Oxy-;Combus- jin Lime-|to Resi-{Residue. gen. tion. water. |:due. ee | ee es | een | 1} 20 20 3641 275” “al 20 41 13 “sl 20 54 22 “al 20 | 74. | 95 5] 20 60 65 58 | 104 32 To understand these experiments, we must, as in the former case, separate the pure gas and oxygen from the azote, and state the nature of the residual gas, as ascertained by the ana- lysis. This is done in the following table. Measures | Residual Gas. of Pure | Measures |Measures |Residual eels Gas. jot Oxygenlof Azote. Gas. Acid. Oxygen.} Azote. 15.4 90 4.58 | 24 4 | 105 4.58 144 >|) 29.57°1 5408) ) 37 | 7 | 19.8 | 5.03 |) er — 15.4 39.12 5.48 46.5 | 8.5 25.8 5.48 15:6 YP MOT. Ae M509 Trsbet 2) region} aes 5.93 - —_— —- —-|——_---——. 154 |, 58.921) 6981 6s |. 7 479 | 6.38 VoL. XVI. —APRIL, 1807. Y It 258 Experiments and observa- tions on the in- JNFLAMMABLE GAS, It is remarkable, that the whole of the gas was never con- sumed in any of these experiments, though there was present flammable gas 1n,every case a much greater proportion of oxygen than was from peat. necessary. Neither did the proportion of residue vary nearly ‘as much as in the former case. The following table gives the proportion of gas and oxygen consumed in each experi- ment. Oxygen con- Gas consumedisumed. 1 | 11.48 9.50 9.93 10.07 | 8.68 13 Oe |_| The oxygen consumed in these experiments was greafer than in the preceding. The proportion of carbonic acid is appa- ' rently less, because the experiments were made over water, and the bulk was more diminished by the combustion than in the former case. When they were repeated over mercury, I _ obtained an average of 8.5 measures of carbonic acid gas from the preceding proportions of inflammable gas and oxygen, which gives us 81.4 measures of carbonic acid gas for 100 of the gas from peat consumed. The mean of these experiments ahd the former gives us nearly 102 measures of oxygen consumed, and 8} measures of carbonic acid formed, for every 100 measures of pure inflam- mable gas burnt; and these proportions I consider as approdch- ing as near precision as We can expect to go, according to the present mede of experimenting. . 11. Having INFLAMMABLE GAS. 259 11. Having thus ascertained the properties of the gas from Experiments peat, we may easily determine whether the opinion by Mie ee eran ae) William Henry, be well founded, namely, that this gas is. a fathmable gas mixture of the inflammable gases with which we are already ‘om Peet. acquainted. yo Of the four known inflammable gases, namely, the olefiant., gas, carbureted hydrogen, carbonic oxide, and hydrogen, of which alone, from its properties, it can be a mixture, we must ‘exclude the first, because the bulk of the gas from peat is not sensibly diminished by oxymuriatic acid. Only three hypo- theses, then, can be formed ; namely, Ist, that it is a mixture of carbureted hydrogen and carbonic oxide; 2d, that it is a _ mixture of carbonic oxide and hydrogen; or, 3d, that it is a! mixture of these three gases all together. Let us examine — these hypotheses. According to the first hypothesis, our gas is a mixture of carbonic oxide and carbureted hydrogen. The specific gravity of carbonic oxide is . . 9560=a carbureted hydrogen 6000=6 gas from peat’. . . 8128=c Let these numbers respectively be denoted by the letters a, b, and c, and let the portion of carbonic oxide in the mix- ture be «, and that of carbureted hydrogen, y; then, by a well- known property of fluids, we have x: y::c—b:a—c. Hence, since x + y=100, we obtain «=59.78 and y=40.20; so that if the gas from peat be a mixture of these two gases, it must be composed of | Carbonic oxide .. . 60 Carbureted hydrogen 40. . 100 Now, 60 measures of carbonic oxide and 40 of carbureted hydrogen, when burnt, combine with the following proportions of oxygen, and form the following proportions of carbonic acid; and the mixture undergoes the following diminution of bulk. pee: 60 260 Experiments, INFLAMMABLE GAS. Oxygen |Carbonic Acid|Diminution of and observa- , consumed.! formed. Bulk. tions on the in-,, : fl bl Pa cl A 60 Bae, Oxide aT 54 33 40 Carbureted Hydrogen} 80 40 80 Foetal? “TOF 94 113 The proportion ofoxygen required by this supposition, does not differ much from that consumed by the gas from peat; but the carbonic acid is more than is formed by he gas from peat. The diminution of bulk is too small. And, upon the whole, the differences are greater than can be ascribed to errors in the - experiments. (2) According to the second hypothesis, the gas from peat is a mixture of carbonic acid and hydrogen. The specific gravity of carbonic oxide . . 9560==a hydrogen .... . 0843==6 gas from peat . . . 8128=c Proportion of carbonic oxide in the mixture =x hydrogen 4:6) 0, are oe a We have, as before, x: yt: c—b:a—c. From this we ob-— tain, as before, x==83.57 and y=16.43. So that, if this hy- pothesis be true, the gas from peat must be a mixture of carbonic oxide 83.5 hydrogen gas 16.5 100 © The following table shews the oxygen consumed, the car< bonic acid formed, and the diminution of bulk, when such a mixture is burnt with the : requisite vie otra of dari. oo Bulk. 83.5 Carbonic Oxide 45.9 16.5 Hydrogen 25.0 - WD Total .. 70.9 Here INFLAMMABLE GAS. 261 Here the diminution of bulk is very different from the Experiments’ truth, while oxygen consumed does not amount to half the real pew dress ni quantity. This hypothesis, then, is still less admissible than flammable gas the former. fromipaaw (3) The third hypothesis only remains to be examined, ac- cording to which, our gas is a mixture of carbonic oxide, :car- - bureted hydrogen and hydrogen. - It is obvious that, according to this hypothesis, the quantity of carbonic oxide present in 100 measures of the gas from peat, can never be less than 60 measures, nor greater than 83; that the carbureted hydrogen can never amount to 40 measures, “nor the hydrogen to 16. But within these limits there is an infinite number ef proportions of these gases, which will pro- ‘duce a gas having exactly the specific gravity of the gas from peat. If, however, we make the supposition, which will be sufficiently precise for our purpose, that one of the gases shall always be present in the mixture, in such proportions as to ‘constitute a whole number of measures, then the number of such mixture becomes limited. Thus, if we pitch upon car- bonic oxide as the gas which must make a whole number of measures, then the number of mixtures will scarcely exceed 20. But it is needless to examine the products of the combus- tion of such mixtures, because none of them approach the pro- perties of the gas from peat so nearly asthe mixture of carbonic oxide and carbureted hydrogen. The following are a few examples. Carbonie Oxygen |Acid consumed.|formed. : - Carbonic Oxide 63 28.35 | 46.70 Carbureted Hydrogen} 34.76 | 69.52 | 34.76 Hydrogen 2.24 1.12 0: Ce ——— Total . . .| 100 98.99 91.46 Y 3 Carbonic 262 INFLAMMABLE GAS. Expeniments! “11! ; Carbonic |Diminu- and observa»: , - Oxygén {Acid tion of tionsomthein- ~ consumed.|formed. |Bulk. “ flammableigas 24 etanee! Pesce} eS Pe cae | Ee aul from peats Carbonic Oxide 65 29.25 ——— i ~\Carbureted Hydrogen} 31.5 63 00 | ohio 63 Hydrogen Ba 1.75 — Total . . .| 100 94 <1 90. boyo4 If we were to examine all these mixtures in succession, we _should find that their properties deviate more and more from those of the gas from peat, as the proportion of carbonic oxide increases, and that the mixture nearest the gas from peat is that in which there is a minimum of carbonic oxide, and of _ course, in which the hydrogen disappears altogether; that is _to say, itis the mixture of carbonic oxide and carbureted hy- drogen already examined, Thus, the presence of pure hydro- gen gas, in the gas from peat, cannoi be admitted; indeed, the evolution of it from a vegetable substance exposed to heat, is contrary to all analogy. But I own I was very much inclined, from the result of the preceding investigation, to consider the gas from peat as a mixture of-carbonic oxide and carbureted hydrogen, and to ascribe the differences between the gas which Texamined and sucha mixture, to errors into which I had fallen in making the experiments. Accordingly, I repeated the ex~ periments day after day, on purpose, if possible, to make them tally with the hypothesis. But as the result of all the trials was constantly the same, I was obliged to renounce it. After- wards, I satisfied myself by a set of experiments, to be de- iailed immediately, that the hypothesis, independent of errors of experiments, is inadmissible. , 12. The gas fiom peat, then, not being a mixture of any known gases, we must eithér admit it as a peculiar compound gas, different from every other previously known, or at leastas containing a mixture of a peculiar-and hitherto unknown gas. The first of these opinions may be admitted at present provi- sionally, till a more complete investigation of the inflammable gases from vegetables enable us to decide whether the second be possible, Let INFLAMMABLE GAS. 963 Let us endeavour, then, from the preceding experiments, Experiments to ascertain the constituents of this new gas. The reasoning 294 observa- from which these constituents are reduced, is founded on a PRR oe gas hypothesis not yet strictly demonstrated, though sufficiently from peat, probable to be admitted by chemists: the hypothesis is, that when a mixture of the inflammable gas and oxygen are burnt, all that portion of both which disappears is converted into water and carbonic acid. The proportion of carbonic acid formed is known from the experiments, while the proportion of water isdeduced from it in the following manner: When oxygen gas isconverted into carbonic acid, its bulk is not sen- . sibly altered; therefore, the quantity of carbonic acid formed _ being subtracted from the quantity of oxygen consumed, leaves, a remainder of oxygen gas which entered into combustion, but. did not form carbonic acid, It is presumed that the re- mainder went to the formation of water. It must, therefore, have combined-with the hydrogen contained in the inflam- mable gas. Now, to obtain the weight of this hydrogen, it.is only necessary to know, that when oxygen is burnt with hydrogen, it combines with very nearly twice its bulk of that inflammable gas. Having thus obtained the quantity of carbonic acid. and of water, formed by the combustion of the gas, as the carbon in the one and the hydrogen in the other were furnished by the inflammable gas, while the oxygen was furnished by the oxygen gas present, we add the weight of that carbon and hydrogen together, and compare it with the weight of the inflammable gas consumed. If the two weights are equal, we conclude that the inflammable gas was composed of the proportion of carbon and hydrogen obtained by the experiments. But if the weight of the gas be greater than that of the carbon and hy- drogen, we are obliged to have recourse to a new hypothesis, and to suppose that the difference of weight is owing toa portion of oxygen and hydrogen present in the gas, which combined during the combustion, and formed water. The proportion of these two substances deduced from the hypothe- sis, is added to the hydrogen and carbon previously obtained : thus making up the whole weight of gas, and giving us the constituents, B From ‘this account of the mode of analysing these gases, it is obvious, that it is liable to some degree of uncertainty. But Y 4 . the 264 Experiments and observa- tions on the in- INFLAMMABLE GAS. | the present state of chemical science does not admit of any thing more precise; for, deducing the proportion of carbon flammable gas ‘rom the carbonic acid formed, I consider it as amounting from peat. to 0.28 of the weight of that gas. For the experiments of Lavoisier and Smithson Tennane appear to me much more precise than those of Morveau, which, indeed, are contra- dicted by the more recent experiments of Berthollet, and were not made in such a way as to be susceptible of beds correct ° results. As the gas employed in the preceding sets of experiments differed a little in its specific gravity, we cannot take the mean’ result of both. Ifwe take the last set, we have 100 inches of _the gas equal in weight to 25 grains, consuming 105 inches of © oxygen, and producing 81.4 inches of carbonic acid. 81.4 inches of oxygen formed carbonic acid 23.6 went to the formation of water, and combined with about 47.2 inches of hydrogen, supposing it in the state of gas. 81.4 inches of carbonic acid contain of carbon 10.6 grs. 47.2 inches of hydrogen weigh — 1.2 Total 11.8 Weight of 100 inches of the gas — 25.02 Deficiency — — — 13.22 These 13.22 grains we suppose to have been oxygen and hydrogen present in the gas, and which combined to form water during the combustion. But water contains very nearly 1-7th of its dei, ye of hydrogen. Hence, they are com- posed of 11.02 oxygen 2.20 hydrogen — 13.22 These being added to the 11.8 grains formerly obtained, give us, for the constituents of the gas from peat, 11.02 oxygen 10.60 carbon 3.40 hydrogen ns - 25.02 oY, INFLAMMABLE GAS. - 265 er, percent. 44 oxygen Experiments 42.4 carbon ~ on aon 10n$ On the ine 13.6 hydrogen flammable gas — from peat, 100.0 As this gas contains three constituents, we may give it the provisional name of oxycarbureted hydrogen, till future ex- periments determine whether it be a mixture or a chemical compound, 13. The gas employed in the preceding experiments, though its specific gravity varied a little, was, however, pretty neaily uniform in that respect. But, in the course of my ex- periments on peat, I obtained portions of inflammable gas which differed very much, both in their specific gravity and in their other properties. from the gas which we have just exa- mined. I select the following experiments as the most striking that occurred. The peat was distilled slowly in a small iron bottle. The gas which came over was received in two different jars. The first portion that came over was found to be a mixture of - 75 infiammable gas 25 common air 100 Its specific gravity was only -7274; which gives for the specific gravity of the pure inflammable peat 0.6365. Hence, 100 cubic inches of it, at 60°, weigh only 19.73 grains. The second portion which came over was found to be a mix- ture of i ee 71.7 inflammable gas 18.3 common air et 100 Its specific gravity was 0.6883, which gives us, for the spe- cific gravity of the pure inflammable portion 0.6082. Thus the two portions of gas differed from each other in their speci- fic gravity, and both of them were much lighter than the gas previously examined. Indeed, they approached very nearly to the specific gravity of pure carbureted hydrogen. With the first portion of inflammable gas thus obtained, I made ihe following experiments. ‘The oxygen used contained 4.5 per cent, of azote, | Nat From o66 INFLAMMABLE GAS. Experiments Ditto, and observa- } Residue af-|washed Nitrous tions on the in- Measures /Measures |ter Com- {with Lime-|Gas flammable gas of Gas. of Oxygen.|bustion. water. added. |Residue. from peat. —s ———$<< | ——$—$____|__ eee } 20 205 23 19 46 4) 2 20 40 42 37a 60 $3 31 20 60 Bis eet ire eas From these experiments we can easily deduce the following table. Residual Gas. Measures |Measures |Measurcs Carbonic) |}-———_—$_$$____+___. lof Gas. fof Oxygenjof Azote. |Residue. |Acid. Oxygen.| Azote. | Gas 1 15 20.1 4.9 23 A 8.84 4.9 5.26 2| 15 39.2 5.8 42 5 A 23,57 5.8 .| 7.63 “Sl 15 58.3 6.7 61.5 6.5 40.34 6.7 To6u.” Pid AA ea 2 i lad NT a LIL di ee I aE oe ee It is curious that, in these experiments, the whole of the gas was never consumed—a proof that the combustion is most complete, when a considerable quantity of azote is present. It is indeed possible, though not probable, that the constant residue was incombustible. We have no means of verifying this by experiment. From the preceding table we deduce the following, which exhibits the proportion of gas and oxygen consumed, and of carbonic acid formed. _ . Diminution of bulk, includ-|Carkonic Gas con- | Oxygen jing Carbonic Acid sumed, apd formed. sat itr ily Aodeer 11.26 21 4. % sae W3Ta 1 see 23 * 5 Me v3), 7.04 | 17.96 | . 25 6.5 Average | varie YS “1498 083 5.17 poines perenne 100 3 iso . 286 64,30 . Here e) Here the proportion ofoxygen consumed increased with the Experiments proportion present. The average result is very different from and observa- : - ; i the in- that obtained in the former experiments ; since here 100 of danimable'sits gas consumed 186 ofoxygen, whereas, in the former case, the from peat. gas consumed only its own bulk of oxygen. The proportion of carbonic acid gas is too small; but over mercury it amounted only to 70 for the hundred ofigas. Here 70 inches of oxygen went tothe formation of carbonic acid, and 116 to that of water. These last must have com- bined with what was equivalent to 232 inches of hydrogen. 70 inches of carbonic acid contains of carbon 9.11 grs. 232 inches of hydrogen — — 6.03 INFLAMMABLE GAS. 267 Ae 15.14 Weight of 100 inches gas 19.73 Residue — — 4,59 _ This residue must be water, and composed of 0.65 hydrogen 3.94 oxygen 4.59 Hence the gas is composed of 9.11 carbon 6.68 hydrogen 3.94 oxygen 19.73 - or per cent of 46 carbon 34 hydrogen 20 oxygen The great difference between this gas and the preceding consists in the diminution of the oxygen and the increase of the hydrogen. s - Now, this gas cannot be a mixture of carbonic oxide and carbureted hydrogen: its specific gravity approaches too nearly to that of the latter gas, to admit any notable quantity _ of the former. It vannot be carbureted hydrogen, because the proportion of carbonic acid formed during its combustion is too small to admit of that supposition. With the second portion of inflammable gas, which had a. smaller y 268 INFLAMMABLE GAS. Experiments smaller specific gravity than the first portion, the enh eX- and observa- _ neriments were made. tions on the in- flammable gas from peat. Ditto, Residue af-|washed Nitrous ter Com- |with Lime-|Gas Measures |Measures of Gas, of Oxygen.'bustion. | water. added. |Residue. “al 20 20 15 daa io (ica Me seeet ie sie elle Moet lr wide gk ome Sah (a6 [leo etase0>} oioe9 7 [angle ope ry From these experiments we obtain the following table. Measures |Measures Carbonic Residual Gas. of Pure fof Pure |Measures Acid Gas. Oxygen. fof Azote. | Residue. jformed. | Oxygen.| Azote. | Gas. | 16.34 19.83 3.83 id 6 1 Re 3.83 | 3.97 2 16.34 38.93 4.73 36 7 20.80 4.73 | 3.97 3 58:03 |, 6.63 156 | 29 ul ond | Bea | 887 It is remarkable that, in these experiments, the residual gas was always the same. This renders it probable that it was incombustible, and that it differed in its nature from the gas which was consumed. The following table exhibits the quan- tities of gas and oxygen consumed, and of carbonic acid formed, in each experiment. . Diminution of, bulk, includ-/Carbonic formed. ip ee ee Doe ae S haneidlbeal a pe Vibe et Average nth 12.37 | 19.46 | 32 7.3 _ Average per cent. |100 158.7 INFLAMMABLE GAS. 269 Here the quantity of oxygen consumed is less than in the gxperiments preceding experiments. On repeating the combustion over re secomtie's if mercury, I obtained 60.63 as the proportion of carbonic acid gammable gas from 100 gas consumed, ; from peat. Here 60 inches of oxygen went to the formation of carbonic acid and 97 to the formation of water. These last must have combined with what was equivalent to 194 inches of hydrogen gas. . . 60 inches of carbonic acid gas contain of carbon 7.81 grs- 194 inches of hydrogen weigh — 5.04 a Total 12.85 Weight of 100 inches ofgas 18.85 Residue 6 This residue must be water, and composed of | 5.15 oxygen -85 hydrogen 6.00 Hence, the gas is composed of 7.81 carbon 5.89 hydrogen 5.15 oxygen "or, per cent. of 41.45 carbon 31.25 hydrogen 27.30 oxygen ‘ 100.00 These experiments were not, perhaps, sufficiently numerous te ensure results that can be altogether depended on; yet, as they were made with all possible care, and some of them repeated two or three times, the errors, I think, cannot be very great. It is obvious that this inflammable gas, especially the last - portion, cannot be a mixture of carbonic oxide and carbureted hydrogen, as its specific gravity is but very little greater than the lightest of these gases. It cannot be carbureted hydrogen, because it neither consumes so much oxygen, nor forms nearly so much carbonic oxide. But asthe gas from peat varies in its specific gravity and in its other properties, it is not improbable that it isa mixture of two gases which vary in their propor- tions. One of them maybe carbonic oxide; but I think I | have 270 Experiments and oberva- tions of the in- flammable gas from peat. Whether radi- ant caloric be propagated with great vee locity. ON HEAT. have demonstrated that the other must be a gas with whicli we are still unacquainted, in a separate state. Jt must be speci- fically lighter than carbureted hydrogen; must contain less car- bon and more hydrogen. Were we to suppose it a species of carbureted hydrogen, it would not be difficult to deduce its specific gravity and its constituents, from the preceding expe- riments. But if oxygen enters into its composition, as-is by no means improbable, the preceding experiments~ do not furnish us with the requisite data. At any rate, it would be premature, at present, to enter upon any such investigation till a greater number of the inflammable gases yielded by vege- tables be examined. II. Observations on Professor Leslie’s Theory of Caloric. In a Let- . ter from Dr. Haurtpay, of Halesworth, . To Mr. NICHOLSON. oh, Avrrer reading Professor Leslie’s very excellent treatise on heat, I confess I became a convert to his ingenious Theory of Radiant Caloric, and then instituted afew experiments, not much different from his, with the view of confirming my opi- nions still more. ‘These experiments, however, which I fear were not performed with éoo much accuracy, have somewhat shaken my faith in the Professor’s theory;-and I am now more than ever convinced of the iruth of the generally-received notion, viz. ‘‘ that caloric is capable of being projected in | right lines with great velocity, and that these lines obey nearly the same laws of motion as the rays of light.” I shall not enter into a detail of the experiments at present, but merely state their results, and the reasons why I have been induced to alter my sentiments; and I shall only advert to those from which. Mr. Leslie has inferred the theory he has formed of radiant caloric. Mr. ON HEAT. oF: Mr. Leslie fournl, that when a screen of tinfoil or even gold- professor Les- leaf, which is 600 times thinner than the tinfoil, was inter- lie’s Experi- posed between the thermometer and the most powerful radi- ™°"* cating surface of the heated vessel, the effect on the thermo- meter was completely intercepted. But that a pane of glass only intercepted four fifths of the caloric, while a sheet of paper , did not intercept so much; and, in order to do away the sup- position, that the effect produced on the thermometer in the experiments with the glass and paper, was owing to part of the radiant caloric passing through their substance, he ob- serves, that this effect was only produced when the screens were* placed about two inches from the heated surface, and that when about a foot from the tin vessel, the rise in the ther- mometer was not one thirteenth of what it was in the first po- sition.. Hence he concludes, that the calorific influence is completely arrested, and that the screen, by this, acquires heat, and, in its turn, displays the same energy as if it had formed the surface of a new canister of the corresponding temperature, Now, Sir, in repeating these experiments, I observed the Facts and ob- same results, but was led to somewhat different conclusions, yaa cat I conceive that the screens of glass and paper do not entirely diant caloris arrest the radiant caloric, but that they allow part of it to pass, Pe. througts and I do so for this reason. When the screen was placed two er inches from the heated surface, I observed it acquired heat not only from the rays which it had arrested, but also by com- munication; when I placed it about a foot from the canister, it had not its temperature varied at all, and therefore I con- ceive the effect upon the thermometer was produced wholly by the rays of caloric which passed through its substance. ; In the first instance, the glass screen received caloric, not Heat transmit. only by radiation, but still more by communication from the tedthrough bo- heated surface; so that its temperature was raised, and it be- St imoam came capable of radicating in its turn; of course, the rays ture being from the canister which passed through the screen, assisted '!S¢4 by those from tha screen itself, piedaued’ a greater effect on the thermometer. But, inthe second case, the screen received no caloric by communication, its temperature was not raised, there- fore it could not, as Mr. Leslie would have it, “ display any energy in causing a fluctuation, or partial swell, in the mass - of air, 90 as to transport the heat. I was anxious to ascertain whether or not the pane of glass, when placed about a foot distant, 272, ON HEAT, distant from the heated surface, did acquire any increase of temperature; but I assure you, if so, I could not discover it by a very delicate air thermometer: so that I conclude, that the effect produced on the thermometer, in the focus of the reflec- tion, was by the calorific rays which passed through the screen. Experiment I consider Mr. Leslie’s experiment with the sheet of ice as with a shect of establishing nothing whatever; for here the rays are not only ice. arrested, but absorbed ; and thougi I am inclined to believe that some of the rays are transmitted, yet that the “ frigorific rays,” if I may be allowed the expression, for the sake of being understood, are more than able to counteract any effect which they could produce. Remarks on In the last experiment which I shall at present notice, and the experi- ment with Which Mr. L. regards as the experimentum crucis, I think he glass, does more to establish the fact, that part of the radiant caloric does pass through glass, than to make good his own theory ; for here we see the effect produced, when there is a certainly . that none of the radiant caloric can pass, and we find that this effect is less ceteris paribus, by two degrees, than when there was a possibility that some part of it might pass; and if we compare that with the quantity which passed through the glass inthe former experiment, we shall find that they are nearly equal; and as metallic surfaces reflect the whole of the radiant caloric, I conceive there is but little difficulty in accounting for the striking difference which he observes took place when the tin coatings of the panes of glass were on the outer side. ~ I admit, with Mr. Leslie, that the calormfic emanation is inca- pable of permeating solid substances which are opaque; but when dight can pass through, I am inclined to believe that General Con- radiant caloric is also capable of finding its way, or, in other clusion, | __ words, that radiant caloric is capable of passing through trans- parent solid substances. * Sir, I have ventured to trouble you with these rather puerile observations, with the view of drawing some of your corres- pondents to the subject. It is a field in which much may yet be done. I am, Sir, - Your very obedient Servant, ANDREW HALLIDAY, M.D. Ill. DESCRIPTION OF A DRAG. aft 273 Ill. Description of « Drag for raising the Bodies of Persons who have sunk under Water. By Dr. Cocan, of Bath *., SIR, Brow the Reports of the Royal Humane Society for the Premium for a year 1805, I learn, that a premium is offered hy the Society drag. instituted in London, for the Encouragement of Arts, Manu- factures, &c. * To the person who shall invent and produce _to the Society a cheap and portable drag, or other machine, ‘superior to those now in use, for the purpose of taking up in the best and most expeditious manner, and with the least in- jury to, the bodies of persons who shall have sunk under water:” and accordingly I beg leave to submit to the inspec- tion of the Society two models. I have long, Sir, been discontented with the construction Account of the of the drags which have hitherto been in use, both in this and ieee in other countries. Those used in Holland are not more than three or four inches in diameter, with very long and sharp -points. They cannot therefore be properly applied to a naked body; and were not the Dutch sailors and boatmen, who are most exposed to danger, very thickly clad, they might be pro- ductive of mischief. 1 attempted, when resident in that country, to make some improvements, by turning the points obliquely inwards, so as to catch the clothes ef At pene- trating deep into the body ; but still these were only appli- cable in cases where the subject fell into the water in his clothes, The drag which is now used in London is, in many respects, exceptionable; it is clumsy and dangerous. The design of establishing a Humane Society at Bath, in- pistory and duced me to reconsider the subject with more attention; and the result has been the construction of two drags, according to ~* * For which the Society of Arts gave the Gold Medal, 1306. “Vor. XVI.—Aprix, 1897. Te the O74. description of DESCRIPTION OF A DRAG. the models which are sent to you, at the desire of that Society. The consideration of economy has induced me to construct the. * drag, Fig. 2. as it may be made at about half the price of the other, and, in some cases, be equally useful. The drag, Fig. 1. is applicable to every case, and the only objection to it is its higher price. You will perceive, by the annexed drawing; the object im ticinstrument. yjew, which is to multiply the chances of laying secure hold of any part of the body, without the possibility of an injury. Had the dimensions been smaller than they are, the drag would not encompass every part of a human body; and. with- out the partition and curvatures at the extremities, the dis- tances would be too great, and the body of a child might fall through the intermediate spaces. By means of the sliding hooks at the ends, the instrument is adapted both to naked bodies, and those which are clothed. As bathers are naked, the sharp-pointed extremities might lacerate in a disagreeable, though not a dangerous manner: or, by entering the skin, they might impede a firmer hold. They are therefore made to recede. But in accidents from skaiting, or in such where the sub- ject falls into the water with his clothes on, the hooks will be of the utmost advantage, as the slightest hold will be sufficient to render the body buoyant. The upper extremities are made both with a socket anda loop, by which they are accommodated either to a pole or a. cord ; or, which is still betfer, to both. In ponds or rivers, where accidents are most likely to happen, should they occur® at a distance from the shore, no pole would be able to reach to a sufficient extent, unless the-assistants were in a boat, which is not at all times at hand. In such cases a cord may be.attached to the loop, and the instrument be thrown te the place where the body is supposed to lie, If the person ex- posed to danger should be able to swim a little, or in any way just support himself from sinking, he might possibly lay hold ef the floating piece of wood, connected with the lower end of, the drag by means of a rope, and thus be brought to shore. This appendage answers another purpose. In rivers parti- cularly, the limbs of the instrument may probably catch roots of trees, &c, and can only be disengaged by pulling the drag DESCRIPTION OF A DRAG, 275 | drag in a contrary direction, by means of the floating wood Description of and rope. as A ea When I said that both pole and cord are preferable to either aecete per= singly, it was for the following reason. I have found, by ex- sons. periments, that a cord tied to the ring or loop, and passing through a hole made at the upper end of the pole, gives a double advantage. The drag, with a pole attached to it, of not more than 10 or 12 feet in length, may be projected several yards further than without it; and in drawing forward the drag, till the end of the pole is brought within reach of ‘the hand, the subject may be raised above the surface of the water in the most proper direction. But a pole of 15 or 16 feet in length is unwieldy, and would even float the drag, unless it was made much heavier. Ifa drag was wanted in those cases only, where it is not necessary to throw il to a distance, then Fig. 2. would answer every purpose. It is obvious that this requires a pole to be fixed in it, so that the hand may direct the projecting parts to the body, ‘which otherwise could not always be done. We have not as yet had an opportunity of trying these drags upon a human body ; but upon an effigy made in every respect as like as possible in form to the human body, both clothed and unclothed, they have answered in the most satis- factory manner. The effigy was brought to the surface in va- rious directions, without cnce slipping from the hold. I shall just beg leave to add, that with two drags and a boat, assistance given in time would almost ensure success. A hook catching a single thread, it is well known, will be sufficient to bring a human body to the surface of the water, or till it becomes visible: a second drag at such time might be applied to any part of the body, so as to secure a firm hold. . The workman charges the triangular drag at one guinea, the other at 12 shillings. A pole 16 feet in length was - charged three shillings. The fangs were estimated at one shilljng and sixpence. Iam, Sir, Your most humble Servant, THOMAS COGAN. Bath, March 1, 1806. “PSC, Taytor, M.D. © Z2 Reference 276 DESCRIPTION OF A DRAG. Reference to the Engravings of Dr. Cogan’s Drag. Plate VIII. Fig. 1, 2, 3, and 4.” Poly Fig. 1. A shows the drag complete, with two cords, B. and C, attached to it; that at the top, B, is fastened toa: ring at D; the bottom cord is tied to a hole.in the iron at E. The six ends of the projecting branches have each a barbed claw, whieh can be slided forward or drawn back, as may be thought necessary. There is a hollow socket in the upper part of the drag at D, so as to admit the end. of a pole to be screwed therein, whenever it may be thought useful. Fig. 2. Is the cheaper or more simple. drag, and intended only to be used with a pole G, fastened in its hollow socket by the screw H, and to be used in the manner of a rake, to bring the body to land. It has barbed claws at the extre- mities of its branches LL, moveable backwards and. for- wards, which claws slide ina groove made in the extremity of each branch. Fig. 3. Shows one of the claws drawn upon a larger scale, screwed to one of the extremities of a branch. In this situa- tion the screw head appears as I, on the outside of the branch, and the claw is within, and does not extend beyond. , the extremity of the branch. Fig. 4. Shows the same barbed claw as its utmost extent, projécting beyond the extremity of the branch. The end, of the worm of the screw, which holds it fast in that posi~- tion, appears at K, : ' . IV. Argu- ORIGIN OF BASALT. IV. Arguments against the Volcanic Origin of Basalt, derived from ats Arrangement in the County of Antrim, and from other “Facts observed in that Country. By the Rev. WiLL1AM , Ricuarnson, laie Fellow of Trinity College, Dublin. Celebrare domestica faetaa—Horace. 277 I HAVE, in the at roosting parts of this Meniett *, discussed Facts and ob- most of the arguments that have been adduced, By differen ‘writers, to stipport the volcanic origin of basalt: and I have examined the facts stated by them, to try how far they apply to this question. { servations re- specting the basalt in the county of Ane trim; adduced to show that it - Tnow return to my own country, which seems more co- is not volcanic. “piously furnished with curious basaltic facts than any of those upon which foreign writers have dwelt so much. as The question (to us at least) is important; for it is the origin of the ground we live upon that we are inquiring into : evety particle of the surface’ of an extensive basaltic area, having merely a thin coat of most fertile earth, slightly cover- ing’ basalt strata, accumulated upon each other to a great height; and most frequently, as it were, bursting through this surface, and displaying, in perpendicular facades, the ar- yangement of the materials that support us. ’ Whetber these materials, so arranged, be formed by the hand of nature, inher original construction of the world; and thus our basaltic strata (in the language of naturalists) be en- titled to the appellation of primary : or whether this construc- tion of our country is to be considered as produced by mighty agents, covering our quondam surface with new and secondary stata, poured forth from the bowels of the earth, is surely an interesting question in the natural history ofour country. And as every writer who has taken up the question of the volcanic origin of basalt, and maintained the affirmative, has recurred * Fromi the Irish Transactions, Vol. X. The two former parts con- gist of An Examination of Desmarest’s Memoir in the Acad. Par. 1771, and of the principal philosophers who have followed his theory. Z 3 - to» 278 ORIGIN OF BASALT. Facts and ob- tothe county of Antrim for proofs, I hope that I too will be servations re- allowéd to extract, from the same source, such proofs as appear eae a to me to support the negative. county of An- In discussing this question I shall abstain from all argu- trim ; adduced ES write s 4 ss to'show that it MeMts. oe pxiorg and limit myself to facts alone; of which .I is not volcanic. hope to/lay before the reader several that have escaped the notice of my predecessors; feeling that I ought to make him some amends for having detained him so long in a barren dis- cussion of opinions, and an uninteresting detection of misre- presentations. Before I proceed to compare the circumstances in which our basaltic area resembles or differs from volcanic countries, I must answer a charge that has been brought against me. I have been told, that it is presumption in me, who never saw a . volcano, to take up a question, the solution of which must depend upon an intimate knowledge both of basaltic and vol- canic.countiies. I first plead example; as not one of my predecessors, who have written upon this topic, has (so far as I can find) exa- - mined both volcanic countries and our basaltic one. I have also authority for saying, that an examination of existing volcanos is not very instructive. Mr. Kirwan. tells us Collini twice ascended Vesuvius, and witnessed its. erup- tions, but complains he got no knowledge by it. Mr, Ferber’s testimony is exactly similar, And, indeed, it is plain that; in an eruption, the lighter materials first projected upwards ; then falling down, and accumulating upon the weightier, that had flowed in lava, must make it very difficult to trace arrange- ment; and this is the surest guide in all questions relative to cosmogony. _ Mr. Strange’s observations on this topic are amusing: .he lets out the secret without knowing it, or availing himself. of it. He says, “ The phenomena of recent volcanos are very « little calculated to give us instruction. A few days tour in « Auver gne, Velay, or the Venetian State, are worth a seven ‘* years apprenticeship at.the foot of Vesuvius or A.tna.” Mr. Strange was not aware, that Auvergne, Velay, and the parts of the Venetian state he alludes to, were originally basaltic countries, in which, afterwards, volcanos erupted. Herg he found a rich. variety of materials: for, besides the common volcanic substances, he found all the varietes of basalt, ORIGIN OF BASALT. ~ 279 dasalt, with the matters that usually accompany them, ochres, Facts and obé zeolites, chalcedonies, and calcareous spar; while at AEtna and S€*vations re- ; ‘ specting basalt Vesuvius he met with burnt matters alone. in the county The points of view in which I shall compare volcanic coun- of Antrim; ad- duced to show tries, as described by the most accredited writers, with our that it is not basaltic district, so often referred to by the same authors, volcanic. are: First. The prominent features and general resemblance. Secondly.. The different arrangement of the materials in vol- canic, and our basaltic countries. | Thirdly. Frequent change in the arrangement of the ma- terials in our basaltic country. ; Fourthly. Striking and radical differences» between our basalt strata, and all known currents of lava: ) Fifthly. Substances found imbedded in our basalt, sais! never in lava. i Sixthly. Different effects produced upon foreign sub- ‘stances (particularly calcareous}, when coming in contact with basalt and with lava. Seventhly. Divisibility of the mass into regular forms, essen- tial to basalt, but never noticed in lava. = - First. The general and leading features of volcanic. coun, tries are admitted to be isolated mountains, generally conic; truncated cones, vast craters, with currents of lava issuing from them, which may be traced many miles. But as all writers upon this topic candidly admit that we have nothing similar in this country, I will not press the argument, nor enquire whe- ther. their modes of accounting for the want of these features be satisfactory or not. Secondly. If basalt be lava, and (as this theory supposes) ence flowed from a volcano, we should expect to find it ar- ranged in the same manner with the currents of lava, which are contigueus to most known volcanos. But here the diffe- fence is most striking: for, while all writers that describe velcanic countries, represent the ejected matters as confusedly arranged, and altogether a heap of disorder; with us we observe, in the disposal of our basalt, the most consummate regularity; every separate stratum preserving steadily its own place, and never breaking into that of another. Besides, most writers admit that currents of lava are sever parallel! to one another: while our basalt strata, accu- mulated O80 ORIGIN OF BASALT. ~ Facts and ob- mulated upon each other, preserve the most steady paral- servations rc- lelism. 4 specting basalt K in the county When we compare onr accumulations of basalt strata of Amrim; ad- with accumulations of currents of lava, which have been duced to show : ; that it is nor eaped upon one another by successive eruptions, we observe volcanic. a most important difference. Currents of lava have always a layer of vegetable earth between them: this is admitted by all parties. For, while those who wish to impeach the chro- nology of Moses, make a prodigious interval between the eruptions necessary for the formation of this layer of earth, Moses’s advocates prove, from facts, that it is often formed in a much shorter time. Interposing layers between currents of lava being thus established, we are to look if any thing similar can be ob- served between basalt strata: but no such thing is to be found. Our basalt strata, whether of the same or of different varie- ties, pass into each other per saltwm, without interrupting the solidity of the mass, or without exhibiting a particle of extra- neous matter between them *. Thirdly. I observed, in a former Memoir, that, on our basaltic coast, nature changes her materials, and the stile of her arrangement, every two or three miles; a fact which op- poses insurmountable difficulties to the position, that the basalt strata, forming this coast, are of volcanic origin. [ - will sélect two or three of these numerous little systems, -and state the order in which the strata are arranged in each of them, ina vertical direction, to give the advocates for their voleani¢ origin an opportunity of exerting their ingenuity, by showing how they manage their volcanos, to make them pro- duce such diversified effects, ; From * I am aware that the ochreous layers, or strata, lying between ‘ our greater basali strata may be stated, as contradicting this pesition. The nature of these ochres (Common to all basaltic countries) has given rise to much controversy ; which, were I to enter into now, 1 would be led too far from the present question. But as ‘this fossil makes a most conspicuous figure in many-parts of Antrim, I think it well entitled to a place in the statistical survey of that country ; the ba- saltic part of which I have undertaken to oblige my friend, Mr. Dubourdicu. On the present occasion I shall only say, that Iaccede to the pein. sion which Mr. St. Fond adopted, after long doubt, and much puzzling ; to wit, “ That these ochres were pure basali, altered by some chemical opera- ‘6 rion of nature, with which we are unacquainted.” ORIGIN OF BASALT. 281 From Ditigce: to Seaport, the fagade (here the base of the Facts and obs arrangement) is composed of strata of tabular basalt; upoi ) Servations re= specting basalt which are accumulated, vp to the summit of Dunmull, co- in the county lumna strata, mixed with others, of the variety called zrreguwar ° f Antrim ; ad- duced to shaw, prismatic. : that it is not East from Carrickarede, the base of the fagade is white V _ lime-stone ; upon which, as long as it continues perpendicular, we find ochteous and columnar strata alternating ; while the hill of Knocksoghy, above, is an uniform alternation of colum- nar and irregular prismatic. The strata, forming the promontory of Bengore, are more ifregularly mixed: six of tabular basalt, five columnar of four different varieties, three ochreous, and two irregular prismatic, sixteen in all: of which, after the tabular that forms the base, notwo of the same kind are contiguous to each other: The voleanist will see that he must find a distinct volcano -for every separate little system surrounding our area; and that he must make the same crater emit different varieties of Java, and frequently by alternation. Fourthly. An examination of-our basalt strata, taken sepa~ rately, and so compared with distinct currents of lava, will, I apprehend, turn out as little favourable to their volcanic origin as the comparison of their masses appear fo do. Whoever has read Mr. Desmarest’s Memoir, or even my quo- tations from it, must admit that, if his theory be well founded, all our basalt strata must have once been currents of liquid Tava, and, of course, should resemble those known to have ‘issued from existing volcanos. But, I apprehend, instead of similarity, the most decided differences. will be found be- tween them. Currents of lava, we “re told, are always narrower and deeper, in the vicinity ofthe crater, broader and shallower, as ‘farther removed from it: but our basalt strata are of uniform thickness in their whole extent. There is another point of view in which the difference be- tween basalt strata and currents of lava is still more decided. Sir William Hamilton, Ferber, Spalanzani, and even Mr. Des- marest himself, informs us, that, in all currents of lava, the materials composing them are invariably arranged, in a regular gradation, according to their specific gravities: thus, at the lowest olcanis 282 ORIGIN OF BASALT. Facts and ob- lowest part of the current, compact lava, they cellular lava, servations Te- then scoria, next cinders, and lastly, volcanic ashes. But, in specting basalt ane 3 Sigh: in the county Our basalt strata, nothing similar is observed: the material is of Antrim; ad- uniform; both density and specific gravity the same, through duced to show the whule thickness of our deepest strata. that it is not voleanic. Fifthly. That basalt never was in fusion, appears plainly from the substances found it, and never in lava; and which, from their nature, could not have sustained, the heat of a volcano. ; Of these, zeolite, chalcedony, and calcareous-spar, seem to abound in the basalt of all countries, but never have been no- ticed in unquestioned Java, The first fuses, and the third cal- cines, in avery moderate heat; and, though chalcedony be more refractory, yet exposed to a strong heat, it loses its beauty, and the delicacy it exhibits in its natural state. . These substances are most copiously dispersed, also, through our basalts; but as this topic has already been often urged, I will pass on to substances peculiar to my own country. A variety of basalt, found in abundance at Portrush and the Skerrie Islands, is full of pectinites, of belemnites, and, above’ all, of cornua ammonis: these are dispersed through the whole mass, equally abundant in the interior and on the surface. This basalt vitrifies, and the marine-substances it contains cal- cine in the fire of a common salt-pan; of course, never could have sustained a volcanic heat. Another fact occurs, which seems decisive against the vol- canic origin of basalt. Some varieties of this fossil, contiguous to Portrush and the Giant’s Causeway, upon being broken by a sledge, discover, in their interior, cavities, some filled with fresh water, others bearing evident marks of having once con- tained it. Of these basalts, some were of a different variety from that of the Giant’s Causeway, but of similar grain and hardness; others were precisely of the same variety, columnar, * prismatic, articulated. and exactly the same in grain. At the Causeway itself, I never found any ; but in. some basalts very near it, on the west side, I have met with it: these had fallen from an upper stratum. A most respectable correspondent, to whom I communicated this fact, as new in natural history, tells me, he suspects the water passed in by percolation. Determined to pay all atten- tion ~ \ ORIGIN OF BASALT. 983 tion to any thing suggested from such high authority, I took Facts and ob- my friend, Mr. Joy, to the spot where I used to find the water pcohees bia in the greatest abundance (Ballylagan).. We broke several] jin the county stones, and, where we found water, observed that, at first, it of Antrim; ad- wet the whole fracture evenly; but, as it evaporated gradually, duced to show the wet was confined to cracks, diverging from the little ca- volcanic. vity that had contained the water. These, therefore, we at first supposed must have been the passages through which the water had made its way: but, on attentively examining the cracks, we. perceived that, as they radiated from the cavity, they diminished in breadth, and finally: terminated in the solid stone; of course, that the water had not come in by 4 them. * . Another fact seems conclusive against ee altion: I never fousiid) in our basalt, any cavities but those which contained water, or which bore evident marks of having been once filled with it. We have, therefore, this alternative: Either the water first made its way through the compact tissue of the basalt, then collected, and dilated itself with such force, as to form rounded cavities, often larger than a pistol- bullet, which, on many occasions, it afterwards forsook : . Or, we must admit the water to have been coeval with the basalt: to which, of course, we cannot ascribe an igneous origin. : Sixthly. As we. know the high state of ignition in which lava issues from a volcano, it is ei to expect that, - when, in its course, it meets with extraneous substances, it should produce upon them such alterations as are the usual effect of intense heat, applied tothese same substances. Basalt, likewise, is often found in contact with similar matters. Hence, by a minute examination of these contacts, we have an ob- vious mode of ascertaining, whether the basalt also had en- countered them in the same state of ignition we know the lava did, As my country, toa great extent around me, is composed of nothing but basalt and lime-stone, I have no other substance but lime-stone upon which I can make cbservations. This, however, apprehend, will be found abundantly sufficient to decide the question. About one hundred yards from the beautiful cavern, called Long O84 ORIGIN: OF) BASALT: Facts, and ob- Long Gilbert, near the eastern ‘extremity of the. calcareous tek ay ntbi facade, a mile from Portrush, we-find, half way. up the preci in. the county pice, a vast basalfic rock, insérted in the:middle of the lime- of Antrim ;ad- stone mass, and, atthe contact, so united to the lime-stone, as “duced to show that it is not !0 form,with it, but one: solid mass. r only dow volcanic. The peninsula of Kenbaan, near Ballycastle, is; the, spot where basalt and lime-stone come in contact in every possible way. Pieces of lime-stone of all sizus, imbedded in the basal- tic mass, and:similar fragments of basalt, dispersed in like man- ner through the lime-stone, and, in the precipice above, strata of basalt, and lime-stone alternating. . Here the opportunities of examining the contact of basalt and lime-stone are number- less; and, on every occasion, I found them united solidly; the line of demarcation correct, as if drawn by a pencil ;. not the least trace of calemation, such. as might be expected from the calcareous. matter, coming in contact with so glowing a mass, as this theory supposes our basalt to have been,* This unexpected circumstance has somewhat embarrassed the veleanisis; who, to account for it, have been driven to various exertions of their ingenrity: but not one of them seems ever to have inquired what was the result, when calcareous matters came in contact with actual lava, as it flowed: Here an obvious mode presents itself, of deciding the question, whe- ther basalt and lava havea common origin: for, if their. con- tacts with calcareous matter produce ‘the same effects upon it, we have a.strong presumption in favour of the affirmative. On the contrary, should the effects turn out to be totally different, we have a conclusive argument in support of the negative. » Whetherthis mode of bringing the question to issue did not occur to the gentlemen who support the volcanic origin of basalt, or whether they did: not dike. to: commit: a favourite theory to so rude a test, 1 will not —presume to conjecture. Direct evidence, with ai view tothe question, I admit I have none ; * The result of my observations, on.the contacts of basalt and lime- stone, perfectly correspond with those of Mr, St, Fond, in Vivarais (Min. des Volcans, chap. 15,) Dr. Hamilton, I admit, saw things in 4 different point of view: but as he does not refer us to the places where he examined these contacts, I cannot bring the point to issue in my country.) | 9 ' ORIGIN, OF BASALT, 235 none ;, yet, by an attentive examination of different writers On Facts and ob- volcanic subjects, I find pretty good light is thrown upon this pratt ot topic. The evidence I willadduce, is,) Lconfess, indirect, and jn the. county the mention of the subject incidental; yet I do not, therefore, of Ane : ae give it less weight; for, siace I engaged in polemic natural en cit a history, J have. discovered, that a reliance on positive asser- volcanic. tion is not the surest mode of obtaining truth. _ The first evidence I shall produce, to the effect of apes glowing lava upon calcareous substances, is that. of Lord Wine chelsea, whose letter to King’ Charles II. (queted by Sir William Hamilton), giving an account of the great eruptionof “Etna, in/1669, says: “‘ Where the streams. of lava meet with rocks and stones of the same matter (as many are), they melt and go away with the fire. Where they meet with other com- .positions (calcareous, no doubt), they turn them to lime or ashes.” ' Mr. Ferber’s testimony on the subject is decisive. He gives — ‘us, in his eleventh,letter, a catalogue of ejections from Vesu- vius; of which No. 6 is, by his account,‘ white lime-stone or matble, in: loose pieces, some burnt and calcined.” He ob- serves, ‘they are found, likewise, in the ashes and lava, and _then constantly calcined and farinaceous.” Again, letter 14, he says, ‘‘ at Monte Albano, the lava, as well as the piperino, contain calcined fragments of time-stone.” Tozzetti di Targioni, in his elaborate account of the mine- ‘ralogical productions of his own country, confirms Ferber’s testimony, as to the uniform. calcination of calcareous sub- _ stances.* Since, then, glowing lava uniformly calcines the calcareous substances it comes in centact with, and basalt produces no effect whatsoever upon them, are we not to conclude, that it - did %* Tozzetti is, full on the subject: He says (page 448, Vol. IX ) ** Se materiali sieno’ di natura web encentte formeranno lave vetrine, se 2 © calcarei 0 apiri, \e formeranno po/verose,’ “Page 250. “ In essi (lave vesuvianc) si vedono misti materie ve- trificaté, con materie calcinate, econ altri quasi non punto toccee dal fuoco,”? | Page 252: * Il. fuoco volcanico, nelle vescere della friontaeha di iis Fiora, abbia offeso—fuse le massolette di metalli, e calcinate Oo Yes trificate, secopdo 1a loro attitudine altre sostanze.” 986 ORIGIN OF BASALT. Facts and ob- did not encounter yee in a state of fusion? which is the point servations. re- in question. specting basalt in the county Seventhly. Upon the last difference I shall mention be- of Antrim; ad- tween basalt and lava, I must dwell a little longer; both be- duced to show ; i that itis not Cause it seems radical and essential; and also, because it lays yolcanic. open some new and curious facts, relative to basalt, which have hitherto escaped notice. ; I allude to that property which all basalt strata, that I ever examined, have, of dividing or separating into regular forms, generally with plain sides. For that this is a principle inhe- rent in the mass, and coeval with its original formation, is obvious, from the striking difference between the plain brown side of the figure and the irregular, granular fracture, gene- rally blue or grey: the former an arrangement of nature, the uniform effect of a cause, with which we are unacquainted ; the latter the irregular effect of a violent stroke or impulse. If the theory we are discussing be well founded, all our basalt strata were once currents of lava, flowing from volcanos. For this we have the authority, or, rather, the assertion, of the founder, and the most accredited supporters of the opinion. In substances, therefore, by their accounts, exactly the same, and of the same origin, (for they use basalt and lava as syno- nymous terms,) we have a right to expect similar properties; and to look for, in lava, an internal arrangement of the mass into regular forms, conformable to what we meet with in all basalts. But nothing similar has been observed in lava, and the description of the Volvic lava is irreconcileablé to this ‘property; for we are told it breaks in all directions, casse en tout sens: and Mr. Desmarest himself mentions this, as a mark of distinction between it and the ere ba- salt. In distinguishing the ice of lava, we have a clew to guide us. We know the process by which it was. formed ; and often, upon inspection, we can discover the original material, the mother stone, by whose fusion it was made. The operation itself, too, enables us to make new distinctions, from the different intensity of heat, and different gradations in cooling. On the contrary, we get little information from inspecting the fracture of basalt. We can tell that, in some, the con- | - stituent ORIGIN OF BASALT. Og stituent materials are more completely blended than in others: Facts and ob- which seems the same thing as to say, there is much dif- Spentine basa ference in grain; a great interval between the coarsest in the county and the finest. But all this is by insensible shades; no oF aa such thing as drawing lines, by which we can mark the that it is nots | varieties of this fossil. Even where other differen¢es are Volcanic. most ‘essential, between the varieties of basalt, inspection cannot be relied upon. For instance, the siliceous basalt, full of marine exuviz, passes, by gradation, from a grain as fine as, jasper, until it becomes indistinguishable from the Giant’s Causeway stone; and even coarser. . If we look to nature for assistance, in classing the varieties _of basalt, we will be no longer at a loss: we will find, she has impressed an indelible character on each variety of this fossil; a specific figure, into which every stratum is divisible, in its whole extent, being formed, as it were, by an ag- glutination of similar figures;* im the same stratum, all of nearly the same degree of perfection; but, when we com. pare different strata, of the same variety, the perfection or _ neatness of the work varies, until it passes into an amorphous. mass. ) Nature seems to have provided, as carefully, for the pre- servation of the distinctive characters, of the different varieties. of basalt, as she has done, to prevent confusion in the several tribes of the animal and vegetable kingdoms. We see our basalts often, by gradation, losing their own forms, but never assuming that of another variety; and, ia the last stage of evanescent form, we can trace an effort to preserve their own appropriate figure. This 1s very observable in our columnar basalt, and in the long horizontal prisms of our whyn dykes, I can also: trace something like a generic difference, be- tween the varieties of our basalt: for some of them have but one principle of construction, to wit, the external vi- sible forms; into which, upon the slightest inspection, they appear to be divided: no internal construction ; the frac- ture irregular, and generally conchoidal. The basalts of this * 1 do not use the word similar in a strict mathematical sense; mean- ing no more than a strong, general likeness, so decided, that the figures ef one variety cannot be mistaken for those of another, \ EgR ORIGIN OF BASALT. Facts and ob- this class are, the columnar, the irregular prismatic, and servations te- the tabular. I have not been able to discover subor- specting basalt ,. e ae Saal é 5 in the county dinate forms, or an internal -construction, in any of these of Antrim; ad. basalts. m oe “4 Each Other varieties, on the contrary, are regularly arranged volcanic. internally; the large prism breaking into smaller, some- times to a great degree of minuteness, as in the Portrush silecious basalt. The coarse Portrush Basalt, whose prisms are’ mostly “quadrangular, and the unarticulated pillars of Ballylagan, have likewise the same property, in an inferior degree; while the basalts of our whyn dykes have often their subordinate prisms finished with great neatness.* But the forms into which our basaltic masses divide, are, by no means, limited to prismatic alone. The pyramid is acommon figure in our whyn dykes; and the most per- fect joints of the Giant’s. Causeway pillars, partake both of the prism and of the pyramid, and have also a mix- ture of curve, and plain surfaces: the latter in number equal to the denominator of the figure; while the former amounts to double that number, plus two. Thus, a pen- tagon joint, taken from one of our most perfect -pillars, has five plain, and twelve curve surfaces; but curve sur- faces are irreconcileable, either to crystallization or desic- cation. t We * This subordinate construction is well illustrated, in a drawing of three prismatic stones, taken from a great whyn dyke, now used as a quarry, nearly two miles west from Belfast. The constituent figure here is a triangular prism, whose angles, at the base, seem double the angle at the vertex. My ingenious friend, Dr: M‘Donnel, to whom I had mentioned the curious construction of or whyn dykes, was so struck when he saw the prismatic stones of which this dyke is formed, extracted from the quarry, that he employed a painter to make a drawing of some of them; and he was.so good as to give me a Copy. f+ The acute angled triangular pyramids, which ascend from each angle of the joint, and often reach up to the middle of the incum- bent one, have théir insides sloped away, in an hyperbolic curve; while the grooves in the lower part of each joint adapted to receive these, with similar curvature, added to the former, make twice as many curve surfaces as the figure has angles. The concave and con- ~ vex ORIGIN OF BASALT. We have another variety of basalt, whose surfaces external, and, iff be aliowed the expression, internal, are all curves : its ~ form is round, and it is composed of concentric spheres, like the pellicles ofan onion. This variety Mr. St. Fond himself admits not to be of vol- canic origin. He says (Min. des Vole. page 46), zt must have taken this configuration naturally. Its mode of arrangement, in the places where itis found, seems still more extraordinary. It is generally imbedded in an indurated basaltic paste ; in Mr. St. Fond’s language, incorporée et incustrée dans des massifs de basaite informe. \n this state, it is sometimes built in the tf form of a wall, of which the globular basalt is the stones, and the unformed the cement. I have great reason to believe, that the varieties of basalt in other countries are exactly the same as in our own; and that nature has taken the same pains to keep them distinct everywhere. The columnar basalt, of all countries, corresponds precisely with that of the Giant’s Causeway, and our other groups, as appears from the sameness of their curicus articulations. Our irregular prismatic exactly answers the description of vex bases add two more; but, by Sir Torbern Bergman’s definition, erystais are bounded by plain surfaces. These facts cannot be exhibited in distinct joints; for the cohesion is so strong, that the ascending pyramids inyariably break off, as the joints are separated from the pillar. It is the projecting fracture that remains, which gives the joint the appearance of a mural crown, as was observed by the early writers on the subject. The destruction of these ascending pyramids makes the sepa- rate joint totally different from what it was, when existing in the perfect pillar. To illustrate all this, I give a drawing of two pillars: one, as it ap- pears when long exposed to the air, which acts principally upon the joints; while the dilation and contraction, from heat.and cold, loosens the pyramids, and separates them from the pillar. The second pillar exactly represents the state in which they appear, where the mass is lately quarried into, and the air has not had time to operate, Ladd some joints in their natural state. This nicety of construction abates, as the pillars graduate ‘through imperfection to an amorphous mass; yet occasional traces of it are long observable. Vox. XVI.—Aprit, 1807, 2A the 289 Facts and ob- servations re- specting basalt in the county of Antrim ; ad- duced to show that it is not volcanic, 290 ORIGIN OF BASAET. Facts and ob- the basalt incumbent on the columnar at Bolsena, as given servations té- by Ferber. It is obviously similar to those at La Trezza specting basalt in the county 27d Pont du Baume; and Mr. Mills’s view of the isolated F age basaltic rock at Ardlun (Phil. Trans. 1790), accurately re- that itisnot. Presents this variety, in many fagades, near the Giant’s volcanic. Causeway. Sir Joseph Banks’s account of the stratum, incumbent on . the columnar at Staffa, might serve for our irreguiar pris- matic, in most places; and the moment I shewed my friend, Mr. Joy, our neat pillars at Craigahuller, he perceived the striking likeness between the stratum, incumbent on them, and that covering the grand colonnade at Staffa. The slight accounts we have of the Scotch whyn dykes, shew, that they are formed, like our own, of horizontal prisms. ; And our globular basalts, with concentric spheres, so cu- riously imbedded as we find them at Port Cooan, near the Giant’s Causeway, and hning some whyn dykes at Belfast Lough, are precisely the same with those taken notice of by Mr. St. Fond, at Ardenne, at Cheidevant, at Montbrul; and also by Mr..Strange, in the Venetian state. -Uniil the advocates for the volcanic origin of basalt can dis- cover, in lavas, something corresponding to these eurious cir- cumstances attending our basalts, can they persist in pronounc- ing them to be identically the same? The one (if I may be allowed to use the expression) a /acéitious substance, of known and posterior formation; the other, bearing evident marks of the hand of nature, both in its general arrangement m mighty strata, and also in its numerous varieties, For we know that nature delights in diversifying her operations, and in exes cuting what seems to us the same work, in many: different: ways. . . mute TRANSIT INSTRUMENT. 991 VV. Method of adjusting a Transit Instrument in a Plane of the Mee _vidian. By Sir H.C. Encueriern, Bart. M.P, F.R.S, Kc, To Mr. NICHOLSON. SIR, We Uehctiis over some papers the other day, I found the [gtroductioa, inclosed, which I had drawn up some years since. I do not know that the method of placing a transit instrument, therein described, has been made public. If it has not, I think its ease and accuracy renders it not unworthy of publication. Should you be ofa different opinion, you will be so good as to return it to me. 2 I am, Sir, Your obedient Servant, H. C. ENGLEFIELD. Tilney-Street, March 11, 1807. Let Z (Pl. 8) be the zenith; P, the poles HO, the horizon; Adjustment of ZPI, the meridian circle; ZK, a circle of altitude distant Roms ‘ee Meskenng ae the meridian by a small quantity IK (suppose a degree) ; 1 23 4, levelling < the diurnal circle of the pole star, whose radius is 1° 435’ axis, and Ou nearly; and let the altitude of the pole Be 1°30’. Then, BE ouccor Gana when the pole-star is on the northern meridian, its altitude 3 I, between the will be 49° 45', and its zenith distance Z 3, 40° 15's and let fae ee ACD be a part of the diurnal circle of a star whose sie dis- another more tance is 46° 30’, and N. meridian altitude 50. ekg aed ? Now, suppose a transit instrument, whose axis is accu- R. A. being rately levelled, and of course in the meridian at Z, to point at 31¥¢” the horizon to K, instead of I, the true meridian; then, at 3 (the altitude of the pole-star under the pole), it will point at B, and the arch 3 B will be to IK as the cosine of the altitude 3 [ to radius; but 3 B, measured on the diurnal circle of the pole-star, will be the sine of its distance from the meridian to the radius P 3 or P B; and as, in small arches, the arch of a ZA2 great 292 TRANSIT INSTRUMENT. Adjustment of great circle, or of a small circle, or their sines, are nearly coin- the transit in- cident, we shall have very nearly as Z 3 (the zenith distance) ecelliae, ee to P 3 (the polar distance), so is the value of 3 B, in degrees axis, and ob--of the pole-star circle, to its value in degrees of a circle whose Puls opie od radius is Z 3. Andas the radius Z 3 is to P 3 very nearly as between the 23 to 1, the error of the transit telescope, at the altitude 3 I, transit of the will be measured by a scale (if it may be so called) 23 times as pole-star and of i qa another more great as itself. distant from Now, let there be another star, A, whose northern meridian the pole; the : i, Z . R.A. being altitude is as small as it conveniently can be, for example, 5°, given. whose polar distance is, therefore, 46° 30’, and whose right as. cension is the same as that of the polar star; then, if the transit telescope be in the meridian, both these stars will pass through itat the same time; butif it be out of the meridian by the quan- tity IK, the star A will pass through it when it comes to C, but the polar-star not till it comes to B, when the star A is got to D, in ifs diurnal circle. - The value of AC being therefore foynd, by multiplying IK by the cosine of its altitude AJ, that value, being reduced to the angular value to the radius PA, will give the time of the star A passing through the transit telescope, after the time of its passing the meridian ; and the same operation being per- formed for the pole-star as before directed, the difference of these times will be the error in time of the transits, answering to the given deviation IK of the transit telescope. And tables having been previously constructed for such stars as shall be thought convenient, the transit telescope may, in a very short- space of time, be set to the meridian, with a degree of preci- sion unattainable’ by any other method. Ifthe star A precedes the pole-star in its passage under the pole, no tables are requisite, nor any thing necessary to be known but the exact difference of the right ascension between the two stars; for, having observed the transit of the star A (the instrument being previously brought near the meridian, suppose halfa degree), then elevate the telescope to the pole- star, by moving the horizontal adjustment of the axis: keep the pole-star on the middle wire till the due interval of time between their transits is elapsed; the instrument will then be extremely near its true position; and, by repeating the obser- vation once more, will be brought to a perfect exactness. Or, ifanother star, following the pole-star in its passage, be ob- piste served TRANSIT INSTRUMENT. © ~ 293 served on the same evening, if the times elapsed between their Adjustment of transits are equal to the tabular difference or their right ascen- rane Ara sions, which will probably be the case, the accuracy of the levelling ays first placing the instrument will be immediately ascertained. pe is Other stars near the pole may be made use of in the same ference of time manner as is here described for the pole-star, but with propor- richie a tionally less advantage; as the polar distance in increased. Bate oe ead ae © It is also obyious, from the figure, that the transit of the another more pole-star above the pole, may be also used, and that with ee nearly, though not quite, the same advantage as the transit be- R. A. being - low the pole. OM lia The same method may also be applied with equal ease, if the second star A pass the southern meridian instead of the northern. The slowness of the pole-star’s motion, though it renders its transit uncertain to a few seconds, cannot materially affect the accuracy of this method, as an error of ten seconds of time in the estimation of its passage; which is certainly more than can be committed, would not cause an error of a third of a second of time in the passage of stars near the equator. Example of the Computation with the Numbers given above. Star A. Pole-Star. Sin. 1K 8 241355 Sin. IK 8.241855 Sin. ZA 9.998844 Sin. Z3 9.810316 Sin. AC” . 8.240199 Sin. 3B 8.052171 ‘Sin. PA — 9.860562 Sin. P 3 —8.484848 Sin. APC 8.379637 Sin. 3PB 9.567328 APC 1°22' 20" 3 PB 21° 40/10" In time 5m 294s In time 1h 26™ 404s The error ofa degree, therefore, in the position of the tran- git telescope at the horizon, causes the star A (o pass through it 5h. 294s. in time later than it ought, whereas, the same error causes the transit of the pole-star to be Ih. 26m. 403s. later than it ought; and the difference between these two times, viz. lh. 21m. Lits. will be the difference’ of the ob- _ served time of their transits, owing to the error of the position of the transit telescope, their real right ascensions being sup- ~ posed the same. Vi. 29% VARIATION OF THE COMPASS, VI. ©bservations on the Variation, and on the Dip of the Magnetit Needle, made at the Apartments of the Royal Society, between the Years 1786 and 1805 inclusive. By Mr. Georcs Ginpin.* Of the Variation Compass. Yariation com Tue variation compass, used in making the following obser- sph Slog vations, is the same instrument used in former observations of ; the variation, and published by the Society in several volumes of their Transactions; and as a particular and accurate descrip- tion of its construction was given by Henry Cavendish, Esq. F. R.S. in the LXVIth volume, it will not be necessary to say any thing hereon the subject. But these observations being the first that have been communicated since the compass was put up in the Society’s apartments in Somerset Place, it may not be amiss to point out its situation in the house at the time of observation, and the method pursued to attain such allow- ances as were proper tobe made in deducing the results here given, Its situation, 1. Fhe compass in the house, at the time of observation, ra ed © was placed in the middle window, on the south side of the gouth mark dee Society's meeting-room, upon a strong mahogany board t$ scribed. inch thick. Against the opposite building the dial-plate of a watch is fixed, making an angle with the true meridian of 31° 8/,8. tothe eastward, as a mark to which the telescope of the compass was adjusted. To obtain the angle that this mark made with the true meridian, I fixed a transit-instru- ment on the mahogany board above mentioned, precisely in the same place where the compass had been placed, and hav- ing adjusted its telescope to the same mark, the transits of the sun and stars over a vertical circle passing through the zenith and this mark, were observed; and the angle contained bee i ; tweek * Philosophical Transactions, 1896, WARTATION OF THE COMPASS. _ tween the said mark and the true meridian, was found by com- -putation to be 31° 8,3 as above. 2. For the purpose of ascertaining what error-there might be, ‘from a-want of parallelism between the line joining the indices and the magnetism of the needle, and thereby to de- termine whether, in the usual method of observing, the in- dices shew ‘the true angle which the direction of magnetism makes with the first division or zero, a great many observa- tions were made “on both ends of the needle, and with both sides of the needle uppermost (the cap of the needle being made to ‘fit on readily on either face for this purpose), viz. north end and south end in its upright position, and north end and south end with the needle inverted, and the mean of the four giving the angle greater by 2’, than that shewn by the north-end in the upright position of the needle (which was the end always used in these observations), two-minutes have been added to all the observations read from the instru- ment, as the correction for this error to angles on the east side of zero, and subtracted from angles on the west side, to obtain the true angle; which error to angles on the west side, ‘however, only occurred when the instrument was-taken out of doors, to determine the effect of the iron work of the building. 3. The variation compass being placed in the: house for ob- ‘servation, could not be supposed to be entirely out of the in- fluence or iron; I was therefore desirous to ascertain how far that influence might extend: for the determination of which, the following method was adopted. Having caused:to be sunk into theearth, to some depth, a strong post, in the wood-yard of Somerset-House, at ai consi- derable distance from the influence of any iron, on which the compass might be placed, and from which station there-was a convenient mark, at a proper distance, to which its telescope might be adjusted: 1 took the compass there at those times of the day when the needle was stationary, viz. morning and afternoon. Before the compass was carried out of doors, ob- ‘servations were made in the room; then it was taken out of doors to the above-mentioned station, for observation there ; and the observations were again repeated, after the compass hac been restored to its situation inthe room; so that had any wlteration taken place in the interval, such alteration would 2A 4 have 295 Method of as certaining the true ‘line of magnetic di- rection, by ine ~ verting ‘the needle —and of ascer taining the in= fluence of iron in the buildings =- 296 VARIATION OF ‘THE COMPASS, have been detected; but during the whole series, no material difference occurred between the observations made in the house betore, and afier those taken in the yard. —by observa- The observations therefore made in the yard, compared tions made out with those taken in the house both before and after those taken of doors, and ; i Afi comparedwith Out of it, formed the comparison for obtaining the error, or the those within. effect of the iron-work of the room on the needle in the house, and there is reason to believe that considerable accuracy has been obtained. They are as follow: ; By a mean of.20 sets, or 200 obsefvations taken with the compass in the yard, compared with twice that number taken in the house, before and after those taken in the yard, the variation observed in the house was found to be greater than that observed in the yard by 5’,4. The mean of nine sets of observations taken in the morning giving for the error 5’,5 5 and the mean of eleven taken in the afternoon giving for the error 5',3. The variation in those tables have therefore been lessened ‘by the above-mentioned quantity 5',4, as the error for the effect of the iron-work of the room on the needle in the house. Coroborating I must not omit to mention, that of these 20 sets of obser- oa acd vations mentioned above, nine only were made with the com- .s pass in the same situation, and eleven in that ofa different one; for, after nine sets had been taken, a pile of boards was put up between the compass and the mark to which it had been ad- justed, which made it necessary to remove the post on which the compass had been placed, a few feet to the westward of its former situation, to clear it from the said pile of boards; and eleven sets of obsérvations were made from this new station, with the compass adjusted to the same mark it had been ad- justed to before, and the angles that this mark made with the true meridian from each of these stations, were ascertained by placing a transit-instrument precisely where the compass had been placed, and observing the transits-of the sun and stars, in the same manner ashas been described in finding the angle of the mark that the compass was adjusted to in the house. And it is conceived that this accidental circumstance adds some weight to the accuracy with which these operations were per- formed, as the error from the two results of nine, and eleven, does not differ so much as'0',5 from each other. Dipping VARIATION OF THE COMPASS, - 07 Dipping Necdle. The dipping-needle with which the observations in this The dipping- communication were made, being the same instrument used in 2¢¢dle. former observations of the dip, and it having also been de- scribed by Mr, Cavendish in the paper before alluded to, it will not be necessary to say any thing of its construction here. Its situation in the house was in the eastern window in, the meeting-room, next the door. As the observations made with the dipping-needle were not affected by any other source of error than that of the iron-work of the room, in order to ascertain the quantity of error, the instrument was taken out of doors at two different times, ‘after an interval of ten years, differently situated each time, and the observations made at both these times out of doors, com- pared with the observations made in the room, giving for the error 20’ more than the dip was found to be in the room, and both agreeing to one minute; that quantity has been added ta allthe observations made with the dipping-needle-in the room for its error, as affected by the iron-work of the room. Although a valuable paper on the diurnal variation of the Canton’s ob- . . . servations on- horizontal magnetic !needle, by the late Mr. John Canton, diurnal varia- F.R.S. was published in the first part of the List volume of tion. Those of the Phil. Trans. for the year 1759, containing a great number oes of observations made at different and irregular times of the day through six- throughout the year, yet, it appeared to me, that if the varia- ‘°°? Pann, tion were to be observed at short but stated intervals of the day for one year, the results would perhaps not only prove more satisfactory in determining the times of the needle becoming stationary, but would show its progressive and regressive mo- tions better than if observed at irregular intervals. To effect which, I imposed this laborious task upon myself for the space of sixteen months. The observations contained in Table I. in sixteen pages, viz. Tabulated re- from September 1786, to December i787, both inclusive, are sults. the results made at many but stated times of the day, and so disposed, that the progress, or regress, of the variation, may be readily seen by mere inspection.* ; Table ° _* For these, on account of theirlength, reference must be had tothe Transactions, 898 VARIATION OF THE COMPASS, Table If, contains the mean monthly variation for the above- mentioned times of the day contained in Table I. Table III, contains, besides the mean monthly true varia- tion, and mean monthly diurnal alteration of variation, :for :the sixteen above-mentioned months, the mean monthly true va- riation, and diurnal alteration of variation -for many months int the year, between the years 1786 and 1806 inclusive. The numbers put down in Table 1, are each of them.amean of five observations, and often more. Those in Table II. depend on Table I. As the observations from which ‘the true variation has been given in Table III, between the years 1788 and 1805, were too numerous to be all inserted, it has been thought sufficient to give the mean monthly true variation, and mean monthly diurnal alteration of variation only; and they were determined from a mean -of the observations made at those times of the day when the variation was considered least, and greatest which-variations for each month, may generally be. considered as a mean-of 600 observations. Rendede From the observations made by the late Dr. Heberden and the changes of others, about the year 1775, the variation was found to increase rg variation, annually nearly 10/, since that time ‘to the present, its rate of bas increase has been considered as. gradually diminishing*, and for * An cexception to the progressive increase appears between the years 1790 and 1791, as the observations between these two years make it todecrease 2/ or 3’, and subsequent observations to increase again. To what this should be attributed, Tam at a loss to account, unless it arose from the alteration which took place in the iron-work of the room in December 1790, four strong iron braces having been ap- plied tothe girders in the floor of the great room of the Royal Academy (which is over the Society’s meeting-room), in consequence of a cracking noise made from the great pressure of anumber of persons in the room during the time that Sir Joshua Reynolds was delivering a lecture: these braces were applied two on cach side of, and equidis- tant from, the compass, the nearest about 18 feet from it. It may be proper to mention, however, that having been favoured with the varia- tion observed both by Mr. Cavendish and Dr. Heberden, in the above- mentioned years, the alteration of the variation was by the former, nearly the same as in my own, but by those of the latter, greater in both cases. An alteration took place between the observations. made with the VARIATION OF THE COMPASS. 299 for the last three or four years, the alteration has been so very small, as to make it somewhat doubtful whether it may not be tonsidered stationary, but I would not from so short a period conclude that it realiy is so. From the observations of sixteen months, viz. from Sep- Remarks on tember, 1786, to December, 1787, both inclusive, the varia- a (nee ci of tion may be considered as generally stationary ator about 7 or gc, : 8 o'clock in the morning, when it is least; and about 1 or 2 o’clock in the afternoon, when it is greatest ; and therefore it _ has been the practice in determining the tre variation, put down in the tables, to take a mean of the two morning, and the two afternoon observations, made at those times, for the true variation. In March, 1787. The mean monthly diurnal alteration of variation was found to be 15’,0; in June 19’6; in July.19’,65 in-September 14’,8 and in December 7’,6. But on a mean of 12 years observations, from the year 1793 to 1805, the diurnal alteration of variation in March was only 8/5; in June 11’,2; in July 10’,6; in September 8’,7; and in De- cember 3’,7. Table IV. contains the differences for 12 years, viz. from Table of state 1793 to 1805, between the observations of the variation made 0f the variation in the months of March, June, September, and December, or pad a at the times of the vernal and autumnal equinoxes, and summer and winter solstices; by a mean of these 12 years, the variation appears to increase or go westward, from the winter solstice to the vernal equinox 0',80; diminishes or goes eastward from the vernal equinox, to the summer sol< stice 1’,43; increases again from the summer. solstice to the autumnal equinox 27,433 and continues nearly the same. only decreasing 0’14, from the said equinox to the winter solstice. These differences at the time of the equinoxes and solstices have been noticed by M. Cassini, in his observations made at @ipping-needle inthe same years. All the iron braces) were on the north-west side of the needle, and the nearest about 18 feet from it. The allowances made to the observations of the variation, and also of the dip, for the effect of the iron-work of the room, were both a3~ certained-after the above-mentioned alteration in the iron-work took place; but they have, notwithstanding, been applied to the observay sions made before, as well as since that time. 300 VARIATION OF THE CGMPASS. Remarks, &c. at the Royal Observatory at Paris, between the years 1783 Unsteadiness of the needle. Annual in- crease of the variation. and 1788, but the effect was considerably greater in his obs servations, than in those mentioned above; his results how- ever were, in my opinion, drawn from too few observations, being from only 8 days observations about the times of the equinoxes and solstices, which differ considerably among them- selves; and experience teaches us, that magnetical obser- vations, made for a period so limited, are not sufficient for minute purposes: I have, therefore, in the results here given, taken the mean of the observations made during the whole month in which the equinoxes and solstices fall, which appear to me likely to furnish results’ more satisfactory; and all the foregoing observations are to be considered as the results or mean of a great many, by way of arriving at greater accu- racy than could be obtained without; this, however, was found to-be more necessary at some times than at Others; sometimes the needle would be extremely consistent witli itself, so as to return exactly to the same point, however often it might have been drawn aside; at other times it varied 2 or 3', sometimes 8, 10’, or even more: this uncertainty in the needle arises principally, I believe, from changes fn the atmosphere, for a change of wind, from any quarter to ano- ther, almost always produced a change in the needle from steady to unsteady, and vice versd, but it was generally more unsteady with an easterly wind. than when it blew from any other quarter, and most steady when the wind was south or south-westerly. An Aurora Borealis always produced consi- derable agitation of the needle. ‘It has been mentioned in this Paper, that the annual in- Crease of variation was found about the year 1775 to be nearly 10’; and was considered at that time to be gradually dimi- nishing; but it is remarkable that this rate of increase ap- pears, from the annexed Table, to be nearly the same at which it has been found to move between all the different periods in the said Table, from 1580 to 1787, a period of more than 200 years, excepting between the years 1692 and 1723: the observations of Halley in 1692, and Mr. Graham in 1723, make the annual increase 16’: to_ what this diffe- rence could be owing I am at a loss to account: on referring _ to observations made at. Paris for those two years, the annual increase is 14’; subsequent observations made by Mr. Gra- ham VARIATION OF THE COMPASS, 301 ham in 1748, make the annual increase between this year and 1723 only 87,1 fiearly what its rate had been found before this great difference occurred ; and from the variation of Mr. Graham in 1748, and the variation observed by Dr. Heber- den “in 1773, the annual increase is 8',4; the variation in 1773, compared with the variation observed by myself in 1787, give for the annual rate of increase 9’,3; but between _ 1787 and 1795, the annual increase ‘was only 4’,7; between 1795 and 1102, 1’,2; and between 1802 and 1809, only O17. The mean rate of annual increase for the above mentioned period of 207 years, viz. from-1580 to 1787, is 10’. As there appears something curious in the rate at which the Changes in the variation has been moving, from observations made at Lon- variation for don, for a period of more than 200 years, the annual increase ‘nh hag of which during that time continued nearly the same; but in a subsequent period of 18 years only, the decrease of that annual increase became so rapid, that the annual increase in the latter part of it does not amount to quite one minute, [ shall subjoin the following Table, by way of elucidating what is here mentioned. $02 Table of varia- tion for 223 years at Lon- gon. VARIATION OF THE COMPASS, Pa LN A By whom the Variation was observed} Year. | Variation, | Increase. Annual / Mr. Burrows* = - - - 1580 1 Ter Mr. Gunter - - 1622 6 @ + 7,5 Mr. Gellibrand > - 1634 4.6 9,6 Mr. Bondt - - 5 1657 0. O:-. 10,6 Mr. Gellibrandt - = |. 1665 |.) 22WiLa., hoe Dr. Halleyg - re ere te ae 9,7 -——— =. - 1692 6 O 10,5 Mr. Graham - - ie al a 16,0 —_—_— or - - 1748 17 40 8,1 Dr. Heberdenf - f L773. 4 Sly 9s 8,4 Mr. Gilpm - : - 1787 | 23 19 9,3 — —_ - - 1795 OF Ah 4,7 ———————- __- =F 2802 | oe ee dye Ses RINE LTRS - - 1805 i mae: val 0,7 * The observations of Burrows, Gunter, and Gellibrand. in 1634, are taken from Seller’s Practical Navigation, 1676. Burrow’s obser- vations are said to be the oldest and best in the world; longitude and latitude found by dipping-needle, p. xvi. Gellibrand is said to be the first pereon who ascertained the variation of the variation, about the year 1695, Phil. Trans. No. 276—278 ; but if this is the date of the ob- servations by which it was determined, the observations of Gunter, in 1662, show him to have a prior claim; Bond, in his Longitude Found, p- 5 and 6, says, that the variation was first found to decrease by Mr, Jobn Mair, secondly by Mr. Edmund Gunter, thirdly by Mr. Henry Gellibrand, and by himseis, in 1640. + Long:tude Found, p. 3. * } Ibid. p. 15; and Longitude and Latitude found by Dipping. Needle, p. 6. _ .§ Phil. Trans. No. 195, p. 565. | Ibid. No. 383, p.107; and No. 488, p. 279. @ Obligingly communicated by his son, the present Dr. Heberden, Table VARIATION OF THE COMPASS. 303 Table V. contains the dip of the magnetic needle from the pip ofthe nee- years 1786 to 1805. For the first sixteen months, viz. from dic from 1786 September, 1786, to December, 1787, both inclusive, the dritiateyenes dip was observed as freqnently as the variation, but as there de" does not appear to be any diurnal alteration in the dip, to make it at all interesting to communicate so many observations as were made, the mean therefore for each month has been thought sufficient for insertion. To explain the foregoing Table it must be observed, that each of the numbers in the four first columns of the above ‘Table, are each of them the mean of several means, as ex- pressed in the line against those numbers; and as each of those means, are again the mean of five observations at least, éach of the numbers in the first line, said to be the mean of nine means, is therefore a mean of forty-five observations ; and so of all the rest. The numbers in the fifih column, entitled true dip, are the means of the numbers contained in the four preceding columns in the same line with it. . The dipping needles used by Norman, the inventor of the +. dip seeltis dipping needle, who observed the dip at London in the year tohave formere 1576 to be * 71° 50’; and of Mr. Bond, who observed it in + Spain 4 - 1676 to be + 73° 47’; not being so much to be depended century has upon as the needles that have been in use for near a centnry inercased. past, render the progressive increase of the dip from Norman’s time, to the time of its maximum, somewhat doubtful. But Mr. Whiston, whose needle there is reason to believe was more to be relied upon, in the year 1720 determined the dip to bex 75° 10’; this, when compared with many, and very accurate observations made by Mr. Cavendish with several needles, in the year || 1775, who found it to be 72° 30’, makes - the decrease in this period, of 55 years on a mean, 2’ 9 per annum. And from a comparison of my own observations of the dip in 1805, which was 70° 21’, with the above of Mr, Cavendish in 1775, its annual decrease, on a mean, appears to have been 4’, 3; and iis progressive annual decrease, on a mean, in the above mentioned period of 30 years, 1’, 4. : T can- * New Attractive, c. 4. + Longitude found. + Longitude and latitude found by dipping needle, p. 1—94. || Phil. Trans. Vol, LXVI, p. 400, 304 Tt is much to be regretted that observa- tions _of varia- . tions have not been ofiener made. VARIATION OF THE COMPASS. I cannot conclude this Paper without expressing my regret, that so little avail should have been made of the numerous opportunities which have been afforded to travellors and others, in the last century, for making accurate observations, with proper instruments, at land, on the variation in different parts of the world. Such observations would probably have afforded some curious and useful facts, which would have ma- terially assisted in forming a theory much more certain than what we at present possess ; the present received opinion of the cause of the diurnal alteration of variation would be con- firmed or invalidated; its quantity of effect in different places, a most desirable acquisition, would be ascertained ; and we should be put in possession of more valuable and correct information on the variation than can be derived from obser- ' vations made with the common azimuth compass, eyen at bervations * and researches of Halley. land, owing to its imperfect construction. The variation thus accurately obtained at any one period, compared with the variation correctly ascertained at a subsequent period, would give a rate of alteration of the variation which could be relied on. The celebrated Halley thought the variation of so much importance, that he made two voyages for the purpose of making observations on the variation, to confirm his theory advanced in 1613, and soon after he published his variation chart. Since his time no better theory than he left has heen obtained, although it must be confessed that many observations have been made at sea by voyagers; but these observations, made generally to answer the purpose of the observer at the time only, are therefore seldom preserved; for, unless made by authority, which rarely happens, they do not often meet - the public eye; and it must be from observations made with care, and with good instruments, carefully registered, and properly arranged, that any real advantage can be derived. It is hoped therefore, that, in future, attention to this subject will not be thought beneath those who may have it in their power essentially to promote an undertaking so interesting to the philosopher, and so valuable and useful to the maritime world. F; TABLE 7 VARIATION OF THE COMPASS; 5 3 30 1786 Sept. Oct. Nov. Dec. raz Jan. Feb, | —— | | TABLE I].—Mean monthly Variation of the magnetic Needle. 6 A.M.|7 A.M.|8 A.M,J10 A.M.) 12M. {1 P.Mij2 P.M. 23 — 123 7,9123 10,1123 14,5123 29,9193 93,7123 93,9 / i 11,3 12,5 14,5 14,2 ¥5;1 12,8 i 7,4 8.8 10,3 12,8 rosa 17,3 19,7 21; ° / Oo 7 4 P.M le pm ° t 23-bD, 2 S¥5, 32948 SIZS 12, 4 17,7) 17,6, 17,4 ro] U 15,6 15,9 15,8 Q ( 14,5| 15,1 15,0 8 pmo PM.| | 11 P.M. ° 7 J 13,8 14,7 15,0 TABLE 2B . Vou. XVI.—ApPRiIL, 1807, VARIATION OF THE COMPASS. 306 $8 6° 8$ SSIO6LI =~} =F] — | — fos ae Ll- lovecat eR 8°81 68S 6a —— aes ! isl (9'L OE — — — HER L3. 9Z) i— —_ - -- fe O9 toh — — — — fool 6 +t — — —_ — It Iool” jOfL tee — — — — {SIT |0'S Fo — _ =e — {s081 LOOT a OE on] Fan Dd QaASS oo ™~ ~reno (almes) — — tet — ATES aC SN OUI da ee Pe re i LO NRE RE CRETE URN TETAS ELS Sh Se jeuunig "aypaaN’ Iajalspus ay) fo uoyn11 4 fo uothoagy pr powsnep Ayo upeue pup OUTIIE on. uy Ayyjuou umoyy—"}Il ATAV.L TABLE ™ S 69 VARIATION OF THE COMPASS. TABLE Il.—-Mean Diurnal True | Altera- Varia- | tion of tion. | Varia- tion. July £0) = i 1786) — a 1737123 19,6 1788/23 29,8 739) — ‘V1790/23 39,0 1791/23 36,7 1799] — 1793123 50,5 1794123 54,4 1795123 57,1 1796/23 69,2 1797/24 0,3 41793/24 0,0 1799124 1,8 1300/24 3,0 1801/24 4,1 1802|24 6,0 1803|24 7,9 1$04)24 8,4 1305/24 7,8 monthly true Variation, and mean monthly diurnal Alteration of Variation of the = magnetic Needle. Diurnal True | Altera- Variae | tion of tion. | Varia- tion. August. Oo eal, f 23 21,9| 19,4 23 43,6) 12,7 23 48,6) 12,1 23: ene 9,8 Diurnal True | Altera- Varia- | tion of tion. Varia- tion, September. Oe [a a 23 16,4, 14,8 yO went Nog) 2343,9| 11,1 23 O26 2948 23 58,1 8,4 24 0,4 7,6 24. 0,1) 833 24 1,4) 7,6 Qs 14 9,4 24 2,9] . 7,8 24 3,6 137 24, 358). 10,1 24 8,7 8,9 24 10,5 9,5 24 8,9) 9,3 2410,0 9,3 True V aria- tion. Diurnal Altera- tion of Varia- tion. ' October, ey: 23 18,4 23 24,5 23 32, lt 2317,3| 9,9 29: 29;0 Lal y Diurnal True | Altcra- Varia- | tion of tion. | Varia- tion, November. Diurnal True | Altera- Varia- | tion of tion. | Varia- tion. December. o / | 23 18,3. 23 a} 8, 23 41,2 5,4 23 =, 3,1 23 ~" 38 23 59,4 .. 3,6 24 1,3 4,9 “89B2 $08. LIGHT AND HEAT COMPANY, TABLE IV.—Diferences between the Observations of the Varia tion of the magnetic Needle,-at the times of the Equinoxes and. ‘ those of the Solstices. > Years. | March. June. |September |December. 1798} 3.6 Sos Pa ee 1795 Boa — (0,40 FoR S93") == 150s , 1796 | + 7 — D4 We fe th 1,2 | 1797 | + 0.2} — 13) + 1,2] —0O,l R79B | = OL Pe 12 a 0,0 1799 | — 0,3 |} — 0,5 | + °2,3 | — 0j6 1800 | + 1,3 | — 1.8} + 1,8 | — 0,3 L801 oF LO ae ey ee 1802 | + 15] — 1,6] + 3,4] — 1,9 1803 | + 12) — 1,0) + 355 1 4-02 2800). —— dS a i ree B58 lp Dh ie 1805 | — 0.3} —0,9| + 2,2 | — 0,6 Mean! +0/.80 | wee Ue + 2',43| — 01,14 Vil. A few Remarks on a Pamphlet entitled «* Mr. W. Nichotson’s “* Attack, in his Philosophical Journal, on Mr. Winsor and “« the National Light and Heat Company, with Mr. Winsor’s « Defence”—12mo. 56 pages. Mr, Winsor’s Mae Winsor seems to have overlooked the observations in pamphlet la‘e- : ly published. OU Journal for January last, as long as prudence and the in- quiries of his visitors would allow him to follow that mode of conduct. Afier having answered.a question of public.impor- tance openly and without reserve, in my own name, as every man ought, where the character of another can in any respect be brought ‘in question, I may be allowed to decline all contro- versy, and leave Mr. Winsor’s claims upon me and upon the world, LIGHT AND HEAT COMPANY. 309 World, to be settled from the facts as theystand. I think it would be extremely easy to shew the numerous, and, in some instances voluntary, errors and misrepresentations with which his pamphlet is vitiated; but I am called upon by no duty to do this. - Tomy readers, it is, I trust, needless to repeat the truths I a ee have already laid down. I can have no cause of enmity to ticesit. Mr. Winsor; but I am not indifferent to the question, whether the public shall be deluded, when one of that public asks me to give an opinion upon what every man has a right to exas mine. It is this motive which leads me at present to notice his pamphlet, and mduces me not to dismiss the subject with- out a few general observations. ; It certainly is Mr. Winsor’s duty to give all those means of ee satisfaction in his printed proposals, which are usually tendered faction to the when undertakings of credit are offered for public support, Public. The following remarks will shew that he has not done this: 1. He asserts, that a public committee was appointed to His pretended verify his discovery. He ought to have said who appointed aka if them, where are their minutes, and what are their names. 2. He pretends that his patent is vested in four respectable —2n4 also the gentlemen, as co-proprietors, who propose to establish a com- cies ae pany. He ought to have published their names. the company. 3. On behalf of these four concealed gentlemen and him- EitherMr.Win- self, he asks for subscriptions; of which the proposed deposits manly ae amount to one hundred thousand pounds, by twenty thousand oy the holders subscribérs; and there is to be no meeting of the intended are concealed. company till one fourth part of this sum (twenty-five thou- | sand pounds) has been deposited. Mr. Winsor either has an uncontrouled power to draw this £20,000 from the banking- houses, or he has not. Ifhe has not, the sum is in trust either with the four co-proprietors, or with other nominees, or with the bankers. In any or either case, the trust ought to have been declared and published; and the trustees themselves, by name, would in fact stand pledged for the honour and credit of the whole project. ; 4. If Mr. Winsor, in his pamphlet, instead of running into akties ; a Jong and faulty dissertation on the law of patents, had laid nie mas sag iny remarks (since the dignity he asserts has not forbad him to tent, by offerg ‘notice them) before counsel; or if he had asked the simple aoe a question of any eminent legal man—* Whether the granting of counsel, 2B-3 “ licences, 310 Shoal of small whales. WHALES. “ licences, to exercise any part of a patent privilege, to a “number exceeding five, limited by covenant, be not sucha ‘* sharing of the monopoly as will sender the patent void ?”~— He would have shown at once how far I may have presumed to speak positively-where it became me to doubt; and he might have set the minds of his subscribers at rest upen'that point. I have asserted, that if he has disposed of such licences, which he very properly calls sharing the privileges, to a thousand per- sons out of a.limited twenty thousand, as he asserts, he has annulled his patent.. He will not find a lawyer who will maintain the contrary. I am persuaded that the magnitude, as well as the philoso- phical nature of the subject, and the interest which so large a part of the manufacturers of the British empire have in patent rights, will render the preceding observations of sufficient im- portance to require no apology. VIII. Account of the Small Whales in the Seas near the Shetland Isles. By Parrrcx Neitz, 4. M. Sceretary to the Natural Hise tory Society at Edinburgh.* By a letter from a gentleman at Uvea Sound, Unst, I was informed, that, ‘“ on the 21st February, 1805, no fewer than 190 small whales, from six to twenty feet long, were forced ashore at Uvea Sound; and on the 19th March thereafter, 120 more at the same spot, in all, 310. . In this second shoal there were about 500, but very many escaped.” To a series of queries addressed to the same gentleman, I received in sub-~ © stance the following answers. ‘“ They measured from ‘six to twenty-four feet in length: the small ones appeared to be the young of the others. They had two long and narrow pectoral fins, from between four and five feet:to- even nine feet long. They remained at the surface of the water ten or fifteen mis | nutes * From his Tour to the islands of Orkney and Shetland. WHALES. nites, just as the boats were near or distant. They had one small fin on the back. The people called them dotéle-noses, and common black whales, but most generally cwing whales. They had a row of teeth, 14 inches long, in both jaws, about two dozen in number in each jaw. The upper jaw was rather the widest. They had no whalebone in the mouth, and had only one blow-hole, situated in a small hollow at the back of the head. Most of the females were either with young or giving suck, Many of the young ones had got no teeth. They had all very fine black skins, as soft and smooth as silk. They appeared to be very inoffensive animals, and shewed much na- tural affection for each other: when any one first struck the ground, it set up a kind of howling cry, and immediately others crowded to the spot, as for its relief. Sandy giddocks (sand- lances) were found in their mouths.” From information fur- nished, by another gentleman, I further learned, that “ from the tip of the nose to the last vertebra of the back-bone, the “generality of the whales measured twenty feet: that the head was short and round, resembling in shape.the head of a:seal; and the upper jaw projected three or four inches over the lower.” —Numbers of the females (this gentleman adds) were syckling their young when driven ashore; and while they continued alive, the milk was seen to issue from their nipples: of these they had only two, resembling the teats of a cow, but larger.” This kind of whale sometimes appears, in large herds, off the Orkney, and especially the Shetland islands. Being of a gregarious disposition, the main, body of the drove follows the 311 Account of the small whales which frequent the north coast of Scotland, &c. leading whales, asa flock of sheep follows the wedders. Hence. the name of ca’ing whales, bestowed on them by the natives, who well know that if they are able. to guide the leaders into a bay, they are sure of likewise entangling multitudes of their followers. Though the above description proves that they be- long to the genus Delphinus. and are nearly allied to the Del- phinns Orca or Grampus, they appear to me to differ in seve- ral respects from that, or any of the other species described by naturalists, so much at ‘east, as to deserve the attention of gen- tlemen who may hereafter enjoy opportunities of accurate ob servation. I shall briefly enumerate the points of dissimi- larity. * 2B 4 The 312 WHALES, Account of the © The grampus has the snout “ spreading upwards,” accord- small whales ing to Shaw*; “waved upwards.” according to Stewartt ; which frequent , , : : : the north coast °° 78am repando,” as Linnzeus expresses it. But this charac- of Scotland, &c. ter was not to be found in the ca’ing whales, in which the nose was neither spread nor turned up at the end, but rounded and dropping. But I must remark, that La Cepéde (the able con- tinuator of Buffon’s “ Histoire Naturelle,” and whose general accuracy is great) takes no notice whatever of the ‘ waving or spreading upwards,” the “ surstm repando,” mentioned by preceding authors. In the grampus, aeoneerne to Shaw, “the lower jaw is much wider than the upper,” in the ca’ing whale: however, we find that “ the upper jaw is the widest.” The grampus is said, in books, to have thirty teeth in each jaw: the Uvea-Sound whales had only twenty-four in each jaw. But La Cepéde remarks, that the number of visible teeth varies with the age of the animal. In Dr. Shaw’s figure of the grampus (which, I mnst confess, is inferior in accuracy to that of La Cepéde), the pectoral fins ate short and round; according to La Cepéde, they are “larges et a, ovalest.” In the ca’ing whale they are said to be long and narrow,”’—thus bearing more resemblance to those of the Delphinus gladiator (to be afterwards spoken of). «© The back fin,” says Dr. Shaw, “ measures six feet in. height.” In the largest of the Uvea whales it did not exceed two feet. La Cepéde does not make it so long as Shaw. The eye of the ca’ing whale, I am informed, was placed higher inthe head thaw in Shaw’s figure ; and the spiracle, as we have seen, was “ situated in a small hollow at the back of the head,” and behind the eye: no such hollow is delineated in Dr. Shaw’s plate; but this is probably an oversight, as it is distinctly depicted in La Cepéde’s representation of the same animal. The Uvea whales had not the white spot on each shoulder, near the eye, described as appearing in the grampus, and figured * “ General Zoology,’ in loco. + “Elements of Natural History,’’ 2 vols. 8vo. ‘ + “Histoire Naturelle des Cétacées, par le qGtoyen La Cepéde,’ p. 301, 4te. Paris, an xil. WHALES. figured by Shaw. But La Cepéde only says, “ On voit sou _ vent deride Poeil une grande tache blanche.*” The neck, breast, and belly were not, I am told, white, as in the grampus, nor was there a defined line between the dark and light parts. Some ofthe ca’ing whales were, according to my information, quite black; others, especially females, had only alittle grey on the belly. The- grampus, we are toldt, “* seldom remains a moment above water:” the Uvea whales, however, as formerly ob- 313 Account of the small whales which frequent the north coast of Scotland, &c, served, “ remained ten or fifteen minutes at the surface, just as the boats were near or distant.” The grampus is stated by Dr. Shaw tobe a “ very ferocious animal, attacking seals and porpusses:” it has long been con- sidered as the formidable sea-monster spoken of by the an- cients{: but the ca’ing whale appeared to be a very inoffen- sive animal, and the common sand-lance was observed to be its food. Under the name of grampus, a similar animal, called by La Cepéde, le Dauphin gladiaicur, has generally been confound- ed. The dorsal fin, however, stands much higher than in the grampus, and nearer to the head. . The pectoral fin is long and narrow like an oar. It is this species, and not the com- mon grampus, that attacks whales, fastening around them like so many bull-dogs, and making them bellow with pain: hence sailors call it the killer. One of this species was, in 1793, taken in the Thames; a drawing and description of which ap- pears * “ Histoire des Cétacées,’’ &c, p. 300. t Bingley’s ‘ Natural Biography,” vol. ii, p. 152, + The small-eyed cachalot (Physeter microps) must certainly be a much more terrible-looking animal. Its head is yery large, forming indeed nearly one half of the whole body, which is from 40 to 60 feet long. It is known to be very ferocious, haying been seen to attack and tear to pieces the huge Greenland whale. It is not-without reason, there- fore, that La Cepéde rather considers this animal as the sea-monster of the ancient mythologists—from the devouring Jaws of which Perseus delivered the fair candidate for the prize of beauty (Andromeda), and the horrific aspect of which struck terror into the fiery steeds of Hippo- lytus. It wasacachalot of this kind that was, in the end of the year 1769, stranded at Cramond, near Edinburgh, and which attracted many thousands of spectators from that city.—Stark’s Picture of Edinbi urgh, RP, 465, 314 Account of the small whales which frequent the north coast of Scotland, &c. WHALES¢ pears to have been sent by Sir Joseph Banks to La Cepédes who has figured it in his “ Histoire des Cétacées.” ee ae The small whales in question, of whatever species they be, afford a great deal of blubber; and it appears surprising that the value of the oil does not induce some of the Shetland and Orkney gentlemen or some of the few substantial tenants, to prepare and keep in readiness an ample store of harpoons, ropes, whale-lances, blubber-knives, and other implements, so — as to enable their dependants to avail themseives, more com- pletely than is’'at present possible, of the occasional visits of those cetaceous inhabitants of the northern seas. Harpoons and lines are indispensably necessary. The best harpoons, I believe, may be commissioned from Prestonpans, at the rate of 7s.6d. each. A single line for each harpoon would suffice, and that line needs not be of the thickness required for Green- land whales: the Greenland whale-lines cost 51. but aline suf- ficient for the small whales might be had for 2]. sterling. Each boat might carry six harpoons and lines, provided only care were taken to keep the lines clear of each other. . Each man should be furnished with a lance, 2. e. ‘a kind of spear with a wooden handle six feetlong, costing 5s. each. Blubber-knives may be had at 2s. 6d.each, The hooked instrument.called tomakawk or pickihawk, is also very useful for laying hold of the blubber, and keeping it on the stretch till it be cut. If the blubber is tobe barrelled, it should be allowed to lie exposed to the air for a day or two, till incipient: putrefaction be per- ceived ; for the swelling that accompanies the commencement of that process would infallibly burst the barrels. It is scarce necessary to add, that a large caldron would be found very use- ful for boiling down the blubber. The exertions of the Shetland tenants, with respect to such - droves of small whales, must certainly be much cramped by the usage of the gountry, which I have now to relate, and which appears to me equally destitute of foundation in law and in equity. I shall state the usage in the words of Mr. Giffard of Busta, which are certainly above all exception: ‘ As soon as the whales are got ashore (¢. e. by the exertions of the people, ; who, es WHALES.- who, surrounding them with boats, embay them, and force Account of the them ashore), the bailie of the parish is advertised, who small whales which frequent comes to the place, and takes care that none of them are em- the north coast bezzled; and he acquaints the Admiral thereof, who forthwith of Scotland, Se goes there, and holds a court, where the fiscal presents a peti- tion, reciting the number of whales, &c. that the judge may ‘give judgment thereupon, according to law and the country practice. Whereupon the Admiral ordains the whales driven ashore to be divided in three equal parts; one to belong to himself; one to the salvers; and the third to the proprietor of the ground on which the whales are driven ashure*.” It is added, that the minister of the parish demands tithes of them» and that the bailie of the parish claims the head as a perqui- site. Mr. Giffard fortunately informs us, that the “ biggest” of the whales of which he is speaking, “ are from eighteen to twenty feet long.” Let us now examine how the law stands on this subject. *¢ By the leges forestarum, §17 (says Mr. Erskine), all grea¢ ' whales belong to the King, and all such smaller whales as may not-be drawn from the water to the nearest part of the land on a wain with six oxen. But no whales have, for at least half a century past, been claimed, either by the King, or by the Admiral his donatory, but such as were of a size considerably Jarger than there described.” TX * Account of Zealand, by Thomas Giffard of Busta, 1733, in Biblio- theca Britannica topographica, No. 38, + Institute, b. it, tit. 1, § 10, 316 Composition for grounding pannels. It is made of cal- cined bones and wheat flour, Application. Canvas grounds, PANNELS FOR PAINTERS. IX. Method of preparing Pannels for Painters. By Mr.S.Granpi*. Tae the bones of sheep’s trotters, break them grossly, and boil them in water until cleared from their grease, then put them intoa crucible, calcine them, and afterwards grind them to powder. Take some wheaten flour, put it in a pan over a slow fire until it is dry, then make it into a thin paste, add an equal quantily of the powdered bone-ash, and grind the whole mass well together: this mixture forms the ground for the pannel. The pannel having been previously pumiced, some of the mixture above-mentioned is rubbed well thereon with a pumice- stone, to-incorporate it with the pannel. Another coat of the composition is then applied with a brush upon the pannel, and suffered to dry, and the surface afterwards rubbed over with sand-paper. A thin coat of the composition is then applied witha brush, and ifa coloured ground is wanted, one or two coats of the colour is added, so as to complete the absorbent ground. When it is necessary to paint upon a pannel thus prepared, ii must be rubbed over with a coat of raw linseed or poppy- oil, as drying oil would destroy the absorbent quality of the ground; and the painter’s colours should be- mixed up with the purified oil hereafter mentioned. Canvass grounds are prepared, by giving them a thin coat of the composition, afterwards drying and pumicing them, then giving them a second coat, and, lastly, a coat of colour- ing matter along with the composition. The grounds thus prepared do not cratk; they may be painted upon a very short time after being laid, and from their absorbent quality, allow the business to be proceeded upon with greater facility and better effect than with those prepared in the usual mode. Method * The processes of Mr. Grandi being founded upon practice, were supported to the Society of Arts, by certificates from our most eminent painters ; -in consequence of which, and of the exhibition of the Pan- acls, the Society awarded him the Silver Medal and 20 guineas, - PANNELS FOR PAINTERS, 33 72 Method of purifying Oil for Painting, Make some of the purifying oil. bone-ashes into a paste with a little waier, so as to form a mass or bali; put this ball into the fire, and make it red hot; then immerse it for an hour, in a quantity of raw linseed oil, suffi- cient to cover it: when cold, pour the oil into bottles, add to it a little bone-ash, let it stand to settle, and in a day it will be clear and fit for use. White Colour is made by calcining the bone of sheep’s trot- white colour. ters in a clear open fire, till they become a perfect white, which will never change. . Brown Colour is if from bones in a similar manner, only Brown. calcining them in a crucible instead of an open fire. “Yellow-Colour, or Masticot. Take a piece of soft brick, of yellow. a yellowish colour, and burn it in the fire; then take for every _ pound of brick, a quarter of a pound of flake-white, grind them together and calcine them; afterwards wash the mixture, to separate the sand, and let the finer part gradually dry for use, Red-Colour, equal to Indian-Red. Take some ot the pyrites, Red. usually found in coal-pits, calcine them, and they will pro- duce a beautiful red Grey Colour is made by calcining together blue-slate and Grey. bone-ashes powdered, grinding them together, afterwards washing them, and drying the mixture gradually. Blue- Black ismade by burning vine-staiks in a close crucible Blue-black. in a slow fire, till a perfect charcoal is made of them, which must be well ground for use. Crayons are made of bone-ash powder mixed with sperma- Crayons. ceti, adding thereto the colouring matters. The proper pro- portion is, three ounces of spermaceti to one pound.of the powder. The spermaceti to be first diffused in a pint of boiling water, then the white bone-ash added, and the whole to be well ground together, with as much of the colouring matter as inay be necessary for the shade of colour wanted. They are then to be rolled up in the proper form, and gra- dually dried upon a board. “White Chalk, if required to work soft, -is made by adding a white chalk: quarter of a-pound of whitening to one pound of the bone-ash powder will answer alone.. The coloured chalks are made by grinding the colouring matter with bone-ashes. 2 : \ SCIENTIFIC NEWS, &c. SCIENTIFIC NEWS, AND OTHER MISCELLANEOUS ARTICLES. Small portable Fire Engine. Ma. HORBLOWER, of Featherstone Street, City Road, with whose talents the world is well acquainted, has re- quested me to mention a construction of the fire engine which he has made, which renders it of much utility within the apartments of an house. 1 have not seen the engine ; but he states, that it stands in the compass of fourteen inches square and two feet high, and may be carried from one room to another with ease. He finds, by experiment, that the four sides of a bed-room, all on fire, may be extinguished in the space of a minute, by little more than a pail of water. All that is required is to keep it filled in its proper place, and to, work it off every month or six weeks, for the purpose of changing the water and ascertaining that it is in proper work- ing state, Enquiry respecting Grease Spots. A Correspondent requests to be informed of a method of discharging grease spots from coloured goods, composed of silk and worsted. He observes, that it frequently, happens, in the process of weaving, that the tallow or oil drops on the work from the candles or lamps used by the weavers, and forms spots which render the goods quite unsaleable ; and he suggests, that if any of the readers of this Journal should point out a method of discharging them, they would render a con- siderable service to manufacturers. I wish it were in my power to point out the vaneiie here desired from actual experiment; but I must leave the answer to others, and shall only venture to speak in general terms of the SCIENTIFIC News, &c. the means by which spots of grease are usually taken out of piece goods. These methods are reducible to two; namely, absorption and ablution. When an absorbent earth (fullers earth or tobacco pipe-clay for example), is applied wet upon a place which is greased, the oil usually flows into the capil- lary interstices of the earth, as the water evaporates; and, upon beating or rubbing out the dry earth, the vegetable or animal fibre is left clean. When the oil is solid, at the com- mon temperature, as is the case with tallow or wax, it is found necessary to apply the heat of an iron or common fire cautiously to the place, while the earth is drying. In some description of goods blotting paper, or bran, or raw starch, may be used with advantage. In these manipulations the dithiculty of taking out the grease does not seem to be so great as that of avoiding injury to the face of the goods. The method of taking out grease by ablution is perfectly well known, Water acts upon grease by the medium of soap, or less safely by the interposition of an alkalis The chemical action of these, as well as the probability of mischief from applying water to various descriptions of goods, oppose in- surmountable obstacles to their use in many instances. [ have not tried how far the solution of pure ammonia might be , beneficial in processes of this kind. It promises the advan- - tage of quitting the article by evaporation, after the process is over. There is a method, commonly used for taking grease spots ouf of silks, which may probably be imtitled to further extension. Alcohol, or spirit of wine, does not act upon grease or fat oil by itself; but when the volatile oil of lemons, called essence of lemons, is dissolved in that fluid, the com- pound will take out grease spots. The method of applying it is to wet the place, and wipe or rub it while wet with a sponge or cloth. It might be worth trying whether a much cheaper essential or volatile oil than that of lemons might not be used for this purpose. Spirit of turpentine would have an unpleasant smell for a time; but, perhaps, it would not last. Dr. Clanny, of Durham, has just published an history and analysis of the mineral waters at Butterby, near that town. T can- 319 320 SCIENTIFIC NEWs, &e., wd TO CORRESPONDENTS. , Ie would be an unpleasant, as well as a difficult task, for me to state the reasons which may at any time require me, as Editor of the Philosophical Journal, to decline inserting some of the papers which may be sent to me. It is obvious that a variety of very proper inducements may offer. themselves to govern my conduct in that respect, which it would answer no useful purpose to detail. My Correspondents have accord- ingly, in almost every instance, received: this information in private, where it has been required; but, for the most part, I have been allowed to excuse my discretion without enquiry. Among a few papers which remain with me, and are not in- tended for insertion, one from H. B. K. has. been the subject of enquiry and remonstrance from the writer. As he is un- known, I have no other than the present channel to say, that his Paper will be. returned to the bearer of an order, in the same hand writing ; and as he complains of a want of justice in its not having been inserted, IT must remark, that though his discussions appeared to me to have become too extensive for monthly insertion, I should, nevertheless, wave admitted that paper, if I had not thought that the spirit of controversy between himself and Mr, Sylvester was becoming too personal io be interesting to the readers of this Journal. ; IT cannot at present answer the enquiries of R. P. respect- ing the application of muriatic acid to promote vegetation ; Bat I will satisfy myself whether the alledged facts on that behalf may be entitled to attention. SF TEIN TAIT SIS DI TIE LG = Exrata in Dr. Bostock’s Paper on Patm Orn, Page 163, 1. 5, for alexeinons, read slnquinean: l. 9, for flashes, read flakc i. 13, after “‘in” insert ** the. Page 164, 1. 3, from bottom, jr er Yai resins, - Page 166, 1. 11, from bottom, for 52 gs, read 52) gre Ny i5, from bottom, FoR sth gr. read .8 gre Printed by P, Da Ponte, 12, pulahasseleet Oxford-Street. Nicholson as method of fs ae etianst i a SirFtb. > anjust Z +o i): y aR j i a So > ne a ; t } los. formal. VoLXVI PLZ. p. 320. Niholons the ty Sa Tie ai A JOURNAL OF NATURAL PHILOSOPHY, CHEMISTRY AND THE ARTS. MAY, 1807. ARTICLE I. Description of a New Astrometer for finding the Rising and Setting of the Stars and Planets, and their Position inthe Heavens. By Davin Brewster, 4. M. . To Mr. NICHOLSON, SIR, An astrometer for finding the rising and setting of the Description of stars, was invented about thirty years ago, by M. Jeurat, = Homo of the Academy of Sciences at Paris, and is described in the ing the appa- Memoirs of that learned body. The utility of this instru- pet ai qe ment in abridging the computation of semidiurnal ares, where great precision is unnecessary, renders it highly-in- teresting to those who are engaged in the study or practice of astronomy, and has induced me to send you the descrip- tion of a new astrometer, more simple in‘its construction, and more extensive in its oe than that invented by M. Jeurat. This astrometer, represented in Plate IJ. Fig. 1. consists of four divided circumferences. The innermost of these is moveable round the center A, and is divided into twenty- four hours, which are again subdivided into quarters and minutes, when the circle is sufficiently large. The second circumference is composed of four quadrants of declination, Sivided by means of a table of semidiurnal arcs, adapted Vor. RVI.—May, 1807, 2C to 321 NEW ASTRONOMICAL INSTRUMENT. Description of to the latitude of the place. In order to divide these qua~ Foaling drants, move the horary circle, so that 12 o’clock noon the apparent. may be exactly opposite to the index B: then since the ae sour star is the equator, and its declination 0, when the semi- diurnal arc is VI hours, the zero of the scales of declination will be opposite VI. VI. and as the declination of a star is equal to the colatitude of the place, when its semidiurnal arc is 0, or when it just comes to the south point of the horizon, without rising above it, the degree of declination at the other extremity of the quadrant, or opposite XII. XII. will be the same as the colatitude of the place, which in the present case is 39, the latitude of the place being supposed 51° North. The intermediate degrees of declina- tion are then to be laid down from a table of semidiurnal arcs*, by placing the degree of declination opposite to the 0 arc to which it corresponds, thus the 10th degree of south ‘ah declination must stand opposite V" 13’ in the afternoon, and VI" 47’ in the morning, because a declination of ten degrees south gives a semidiurnal arc of V" 13’. When the scales of declination are thus completed, the instru- ment is ready for shewing the rising and setting of the stars. For this purpose move the horary circle till the index B ae points to the time of the star’s southing ; thus opposite to a the stars declination in the scale C, if the declination is south, or in the scale D if it is north, will be found the time of its rising above the horison; and the degree of de- clination on the scales E and F, according as it is south or forth, will point out on the horary circle the time of the star setting. If the rising of the star is known from ob- servation, bring its declination to the time of its rising on the circle of hours, and the index B will point out the time at which it passed the meridian; and its declination on the opposite scale will indicate the time when it descends below the horizon. In the same way, from the time of the star setting, we may determine the time when it rises and comes to the meridian. The two exterior circles are added to the astrometer, for the purpose of finding the position of the stars and planets * The most accurate table of semidiurnal arcs that I have seen, is published in the Tables de Berlin, Tom. IIL. p. 233. Ta NEW ASTRONOMICAL INSTRUMENT. 322 ia the heavens. The outermost of these is divided into Begpntion of 360 equal parts, and the other, which is a scale of am- for detetmining' plitudes, is se formed, that the amplitude of any of the aie heavenly bodies may be exactly oppesite the corresponding the stars, &c. degree of declination in the adjacent circle. The degrees of south declinatien, for instance, in the latitude of 51°, corresponds with an amplitude of 154°, consequently the fifteen degrees of amplitude must be nearly oppesite to the tenth degree of declination; so that by a table of ampli- tudes, the other points of the scale may be easily deter- mined. The astrometer is also furnished with 2 moveable index MN, which carries at its extremities two vertical Sights mn, in a strait line with the center A. The instru- ment being thus completed, let it be required to find the planet Saturn, when his declination is 15° north, and the time of his southing 3" 30’ in the morning. The times of his rising and setting will be found to be 7" 15’, and 10° 45’, and his amplitude 24° north. Then shift the moveable index till the side of it which points to the center is exactly above the 24th degree of the exterior circle in the north. east quadrant, and when the line A B is placed in the me- ridian, the two sight holes will be directed to the point of ‘the horizon where Saturn wili be seen at 7° 15’, the time of his rising. The same being done in the north-west qua- drant, the point of the horizon where the planet sets wilt likewise be determined. In the same way the position of the fixed stars, and the other planets, may be easily dis- covered. If it is required to find the name of any particular star that is observed in the heavens, place the astrometer due north and south, and when the star is-near the horizon, either at its rising or setting, shift the moveable index till the two sights point to the star. The side of the index will then point out, on the exterior circle, the stars amplitude. With this amplitude enter the third scale from the centre, and find the declination of the star im the second circle. Shift the moveable horary circle till the time at which the observation is made be opposite the star’s declination, and the index B will point to the time at which it passes the meridian. The difference between the time of the star’s 2C2 southing, 324A Description of an astrometer DESTROYING INSECTS. - Southing, and 12 o’clock noon, converted into degrees of for determining the equator, and added to the right ascension of the sun if the apparent Situation of the Pars, &c. the star comes to the meredian after the sun, but substracted from it if the star souths before the sun will give the right _aseension of the star. With the right ascensions and de- clipation thus found enter a table of the right ascensions and declination of the principal fixed stars, and you will discover the name of the star which corresponds with these numbers.—The meridian attitudes of the heavenly bodies _ may always be found by counting the number of degrees - between their declination and the index B. The astrometer ‘Inquiry re- specting the means of de- Stroying fleas and other in- sects, may be employed in the solution of various other problems ; but the application of it to other purposes is left to the in. genuity of the young astronomer. I am, Sir, Your obedient humble Servant, DAVID BREWSTER. Edinburgh, April 14th, 1807. Ii. Questions and Remarks concerning the best Methods of de- stroying the Insects which infest Dwellings and Furniture. By a Correspondent. : To Mr. NICHOLSON. SIR, vite I LATELY read in a periodical work some enquiries by a “ trifling Querist’’ respecting the best means of destroying er expelling those troublesome insects bugs and fleas, but particularly the latter. I was in great hope of seeing some communication that might have been useful for this purpose, but was much disappointed to read ina later number a flippant sort of answer, that we might prevent their bite by covering our bodies with tar or pitch, and that their bite might be cured by patience and. letting it alone. The same means,’ Sir, will cure the tooth ach.—Some persons suffer very little inconvenience from the bite of poisonous insects, DESTROYING INSECTS. insects, whilst others, from what cause 1 know not, suffer Inquiry re- severely. Unfortunately for myself I am one of these. The bite of a common flea causes a very considerable degree stroying fleas of pain and inflammation; so great indeed as totally to disturb my rest until either the little animal is satisfied, or till lam fortunate enough to destroy it. If knowledge be valuable in proportion to utility, the means of preventing the distress occasioned by the bite of insects is not beneath the attention of philosophers. Cleanliness I know will prevent the incroachment of these vermin; but no one can guard himself from them by cleanliness of his own person, unless he can prevail on all persons with whom he has inter- course to take the same care. I wish some of your corre- spendents who have pleasure in the study of natural history would bestow some attention on this stibject, and commu. nicate to the public the result of their investigation. It is remarkable that different constitutions are so differently affected by the same poisons. The bite of fleas or bugs is insufferably painful to some persons, whilst others are not at all incommoded. The reason of this might bea subject of curious enquiry, But it would be an important comfort to those who suffer severely, to be acquainted with any means of protecting themselves against such distress. The common head-louse is easily destroyed or expelled from the head by combing into the hair a small quantity of white Hellibore. Whether this drug is equally deleterious to the flea, I do not know, but the experiment might merita trial. Perhaps rinsing the blankets through an infusion or decoc« tion of it, might render them a disagreeable lodgement to any insect. Mercury we know is in every form destructive to the insect tribe, but whether any useful application could be made of it in this case 1am unable to determine. I have known the red nitrate of mercury combed into the heads of children for the purpose of destroying vermin, and I believe with complete effect. Many of the solutions.of this mineral ‘are so corrosive as might injure the texture of the clothes; but perhaps a very weak solution of the acetite of mercury, suppose a grain to a pint of water, might be used to rince the clothes through, without injuring them, or occasioning te a person sleeping in them any unpleasant effects; yet ever 336 Liquiry ré- specting th means of de™ stroying: fleas: : and other. in- sects, HEATING ROOMS BY STEAM. eren this small quantity might be so disagreeable to fleas as to expel them. Sulphur is, I believe, destructive, or at least disagreeable to insects, but I much doubt whether it, could be used in any conveniont form to answer our purpose. Perhaps the sulphur-water, water containing sulphuretted hydrogen, might have some effect, but it would, in most situations, be too expensive for use. It is said that worm- wood is very offensive to fleas. Probably an infusion of it might be very advantageously used to secure us against the intrusions of these troublesome little animals, As it might often be inconvenient to procure the herb fresh, it would be important to know whether the oil, or any preparation .of it that could be conveniently ee otek would answer the purpose. Camphor is said to be offensive to bugs; but though I never made any experiments expressly on the sub. ject, yet I think I am enabled by accident to contradict it. _it might. merit a trial, whether washing the body over with any of these articles would secure us against the bites of fleas, . or bugs, or musquitoes, or gnats. With respect to, _the cure of these bites I can say little. T have heard military _men, who have been in warm climates, speak of the custom of laying a cut lemon by the bed-side, and rubbing the part with, it immediately, on. being bit. If any of your corre. spondents can communicate any useful information on this subject, I shall be. one amongst many others who will feet extremely grateful at being relieved from one of the sé miseries of human } life.” Tam, Sir, Your obedient Servant, _ ' ug ‘ caine J ep : Lat? A. dit. Account of the Method and Advantage of heating Apart. ments and Manufactories by Steam. By sith NEIL SnoperAss*, History and In April 1798 Mr. Snodgrass was engaged by G. “Mackin. account of the tosh and David Dale, Esqrs. to manage ¢ a cotton mill near method of heating rooms - by steam. s*-The Society of Arts gave a premium of Forty Guineas for this useful communication, Dornoch, HEATING ROOMS BY STEAM. 327 Dornoch, in the county of Sutherland. He remained in History and Glasgow for six months after this, superintending the con- pine a ead struction of machinery for the mill. During this period he heating rooms was led to consider of a cheap method of heating the mill, 7 *t°4™- as he had learnt that fuel was extremely scarce and dear in the country in which the mill was situated. It was evident that none of the methods which he had seen practised could be applied, but at an enormous expence; and his experience had pointed out to him important defects and inconveniences in them all. Having observed a mode of drying muslins by wrapping them round hollow metal cylinders, filled with steam, practised at the bleach-fields near Glasgow, it oc- curred to him, that by means of a proper apparatus, steam might be applied to heat a cotton mill, or any other large manufactory. It was evident that this not only would be an ceconomical mede of producing heat in large works, so far as fuel was concerned, but that it would prevent the danger of fire, to which such works, when heated in the usual manner, are much exposed. He communicated his notions toa number of cotton spinners and others, from whose suggestions he expected assistance. But he met with nothing but discouragement, the project being every where treated lightly, or pronouneed to be impracticable. Strongly ‘a impressed, however, with’ the advantages of the plan, the me memorialist persevered in his resolution to make trial of it, and ordered tin pipes to be made for the purpose. These 2B he erected in the mill in May 1799. When filled with steam they at once produced the necessary degree of heat; but the pipes, having been damaged in the carriage, proved not sufficiently strong. Indeed the memorialist was im- mediately sensible, that their position was unfavourable. With a view to some conveniences in point of room, they had been carried up diagonally in one end of the mill, whence the upper sides of the pipes became sooner heated than the lower, which caused an unequal expansion. .. The water arising from the steam condensed in the pipes in its return to the boiler, and also obstructed the steam in its ascent. In order to remedy these defects the pipes were altered, and erected in a perpendicular position, and certain tubes were connected with them, to carry off the water Varisin “es 328 History and account of the smethod of heating rooms by stéam “ HEATING ROOMS BY STEAM “arising from condensation. The whole apparatus, as it stood after this alteration, is pe Ra haks by the drawing, Fig. 1. Plate I. This drawing presents a view of an inner gable, which is at one extremity of the preparations and spinning rooms of the mill. On the other side of this gable there is a space of 17 feet enclosed by an outer gable, and containing the water wheel, the staircase and small rooms, for the accome modation of the work. In this space the furnace and boiler are placed on the ground. The boiler cannot be shown here, as it lies behind the gable exhibited; nor is it of any consequence, as there is nothing peeuliar init. It: may be of any convenient form. The feeding apparatus, &c. are in every respect the same as in the boiler of a com- mon steam engine. A circular copper boiler, two feet diameter, by two feet deep, containing 30 gallons of water, ‘with a large copper head, as a reservoir for the steam, was found to answer in the present instance. The steam is cons veyed from the boiler through the gable, by the copper pipe B, into the tin pipe C, C. ‘From C it passes into the centres of the perpendicular pipes E, E, E, by the small ‘bent copper tubes D, D, D. The pipes E, E, E, are con. ‘nected under the garret floor by the tubes F, F, for the ‘more easy circulation of the steam. The middle pipe E is carried through the garret floor, and communicates with a lying pipe 36 feet in length (the end of which is seen at G,) for heating the garret. At the farther extremity of the pipe G, there is a vaive falling inwards to prevent a vacuum ‘being formed on the ‘cooling of the apparatus; the conse. ‘quence of which would be the crushing of the pipes by the pressure of the atmosphere. Similar valves, K, K, are placed near the top of the perpendicular pipes KE, R; and from the middle one F, the small pipe passes through the roof, and is furnished with a valve at I, opening outwards, to suffer the air to escape while the pipes are filling with steam, or the steam itself to escape when the charge is too ‘necks of which may either pass through, or round, the pipe high. The water condensed in the perpendicular pipes E, E, R, trickles down their sides into the three funnels, L, L, sip the us HEATING ROOMS BY STEAM. 329 C, into the copper tube M, M, which also receives the History and ‘water condensed in C, C, by means of the short tubes N, N. aaa me the The pipe C, C, is itself so much inclinedas to cause the heating rooms water to run along it to the tubes N, N, and the pipe G in *Y stam. the garret has an inclination of 18 inches in its length, to bring the water condensed in it back to the middle pipe EH. The tube M, M, carries back the water through the gable to the boiler, whach stands-five feet lower than this tube. It is material to return the water to the boiler, as, being nearly at a boiling heat, a considerable expence of fuel is thereby saved. | The large pipes are ten inches in diameter, and are made of the second kind of tinned iron plates. The dimensions of the smaller tubes are seen by their comparative size in the drawing, and perhaps they might be varied without inconvenience. - The apparatus erected as here described, has been found sufficiently strong, and has required no material repairs since the first alterations were made. The leading object in the instance under consxleration being to save fuel, in order to derive as much heat as possible from a given quan. tity of fuel, the flue from the furnace, which heats the boiler, is conveyed into common stone pipes placed in the gable. These are erected so as to prevent any danger of fire, in the manner shown in the drawing, Fig.2. The steam with this auxiliary communicates a heat of about 70° to the mill, the rooms of which are 50 feet long, 322 feet wide, and 84 feet high, except the lower story and garrct; the former of which is 11, and the latter 7 feet high. The rooms warmed in this manner are much more whole~ some and agreeable than those heated by the best con- ‘structed stoves, being perfectly free from vapour or conta- winated air. : By various experiments it appears, that the expence of fuel is scarcely one half of what is necessary to prodnce the same degree of heat with the best constructed stoves. The memorialist was the better able to make the comparison, siuce he had previously had five years experience of cotton “mills on what was, at that time, reckoned the most ap- proved platy After 330 HEATING ROOMS BY STEAM. History and.ae- », After having ascertained these results, the memorialist, count of theoo. Apts method of heat- 2 1800 drew a plan similar to that now presented to the. ing reoms by Society, and sent it to Glasgow to his employers, who steam. -"'"S were very doubtful. of the suecess of the scheme. They immediately published the discovery in the Glasgow news. papers, inviting cotton spinners, and others interested, to inspect the plan, In consequence of this public intimation of the method having been successfully practised, a num- ‘ber of cotton spinners turned their attention to it, and adopted it with various modifications, according to the con- venience of their mills, or other notions of improvement. The memorialist afforded to every person who desired it, all the information.on the subject which he possessed. His general recommendations were to detach the condensed water, in returning it to the boiler, as much as possible from the steam; and where tin pipes, or others of similar ~strength, were used, to secure them carefully with safety valves. There are obvious defects in the application of the prin- ciple, as practised in the instance described above. Of some of these the memorialist was perfectly aware at the time of the first construction of the apparatus, though it was out of his power to remedy them; and he has thought it proper to give a detail of the first successful experiment exactly as it toak place: From the pipes being all in one end of the house, the heat. was unequally diffused, and a considerable time elapsed, after their being first heated, before it reached the other end of the rooms. But, as the mill had barely room enough for the spinning machinery, it was impossible. to érect the pipes in-any other situation, or to convey them -along the rooms, so as to produce amore equal distribu- tion of heat. .-This, however, can be so easily effected, when there are no obstacles, such as have been mentioned, that it is scarcely necessary to enter into any detail of the means. Itmay be barely mentioned that the memorialist has fitted up the apparatus in two cotton mills, which are now under his management, belonging to George Houston, Esq. -and Co. of Johnstone, in a manner.which completely dis- tributes the heat. In one of these mills, consisting of .six stories, ‘ HEATING ROOMS BY STEAM: 331 stories, a lying pipe ‘of cast iron,’ five inches in diameter, is History and.ac- carried along the middle of the lower story, about two oa feet from the ceiling, with a- small declivity to carry off ing rooms. by the water. This pine heats the story in which it is placed. epi Tin. pipes, 72 inches diameter, communicating “with~'this lying pipe, are carried up perpendicularly through: all the floors to the top of the house at the distance of seven feet from each other, and form a line of heated- columns in the middle of each room. ‘The same general plan has been followed in the other mill. But there are several irregula- rities in the building, which require a little variation of ‘the contrivances for diffusing the heat to every quarter.~ Some of the rooms having been added since the first erection of the mill, are connected with the main body of the building ecards: Into these the steam is carried by lying pipes, slightly inclined, and communicating with the principal ap- paratus. The steam may afterwards be distributed by other pipes in any way that is thought convenient. The memo- rialist has found no difficulty in conveying, by such means, the steam necessary to produce the degree of heat required jn every variety of situation. In the former of the last mentioned mills, the hibit. cular pipes are connected under the ceiling of the garret by a pipe 22 inches diameter, slightly inclined, the extremities ~ of which pass through the walls of the house, and are pro- vided with valves opening outwards. A connecting pipe, with similar valves, is placed under the ceiling of the third story. These are intended for the more easy circulation of the steam; but the memorialist found, from experience, that with all these aids, the filling of the perpendicular pipes with steam was attended with some difficulty. The steam, when first thrown in, passes up the perpendicular ‘pipe, nearest to the boiler, and, being specifically lighter ? than air, occupies the upper part of the apparatus, compres- sing the air in the lower part of the rest of the pipes, The resistance of the air will thus for along time prevent -the pipes from being completely heated: but this difficulty is “easily obviated by having a valve or valves opening out- “wards, at the lowest part of the apparatus, through which the air, when compressed by the steam, is syffered to escape. 882 | HEATING ROOMS BY STEAM. History andac- escape. In the mill just mentioned, the lying cast irom pipe count of the. ‘gitae 4 3 method of heat: 0 the first story is carried through the gables of the mill, ing rooms by ‘and furnished with valves for the: egress of the air. It ig Si ats “unnecessary to repeat, that the same valves serve for the discharge of the air in heating the apparatus, and of the steam itself, when its expansive force becomes too great. In both mills, each of the perpendicular pipes is provided with a valve, to prevent a vacuum; and in the second mill ‘the lying pipes for carrying the steam into the, detached rooms have each two valves, one opening inwards, and the 2 other outwards. Certificates of five other mills being heated in a similar manner, by the direction of the memorialist, are presented to the Society. The application of the principle to buildings already con- structed, it is presumed, will be sufliciently obvious from the foregoing details. In new manufactories, where the mode of heating may be made a part of the original plan, a more convenient apparatus may be introduced. This will be best explained by a description of the drawing, Fig. 2. which gives a section of a cotton mill constructed in a man- ner which the memorialist would adopt, were he to apply the steam apparatus to a new building, or any other that would permit such an apparatus from its regular construc- tions. In an old mill in this place, an apparatus is now erecting by the advice of the memorialist, conformable to this plan, which is likely to be generally adopted in new cotton mills. stag The furnace for the boiler is shown at a. The flue of the furnace conveys the smoke into the cast iron stove pipes, 1, 2, 3,4. These pipes are placed in a space in the gable, intirely enclosed with brick, except at the small apertures, 5, 6, 7, 8. A current of air is admitted below at 9, and thrown mto the rooms by those openings, after being heated by contact with the pipes. This part of the plan is adopted with a view to prevent, as much as possible, any of the heat, produced by the fuel used, from being thrown away: It may be omitted where any danger of fire is apprehended from it, and the smoke may be carried off in any way that is considered absolutely secure. So far, however, as the memorialist HEATING ROOMS BY: STEAM. 8333 memorialist is able to judge, there seems to be little or no History and ac- _ danger of fire from 2 stove of this construction, . The ibd con oecle greatest inconvenience of a common stove is, that the ing rooms by cockle or metal furnace is liable to crack from the inten. *°*™ sity of the heat. By the continuity of the metal from the fire-place, an intense heat is also conducted along the pipes, which exposes them to the same accident. . Here the smoke being previously conveyed through a brick flue, can never communicate to the pipes a degree of heat suf- ficient to crack them. In like manner the pipes, haying no communication with the rooms but by the small aper- tures, cannot come in contact with any combustible sub. _ stance; and from being surrounded with air, which is con. stantly changing, can impart only a very moderate degree of heat to the walls. The iron supporters of the pipes may be imbedded in some substance which is a bad conductor of heat, as furnace ashes and lime, &c, The emission of heated air into the rooms may be regulated by valves. As the pipes are not exposed to cracking, there is no risk of their throwing smoke or vapour into the rooms. . The boiler 6, b, is six feet long, three and a half broad, and three feet deep. As there is nothing peculiar in the feeding apparatus, it is omitted. ‘The boiler may be placed in any convenient situation. Where a steam engine is used for other purposes, the steam may be taken _ m its boiler,. The pipe c, c, conveys the steam from the boiler to the first perpendicular pipe d, d, d. There is an expanding joint at e, stuffed, to make it steam tight. The steam ascend- ing in the first pipe d, dd, enters the horizontal pipe f,f5 J, f, (which is slightly inclined) expelling the air, which partly ‘escapes by the valve g, and is partly forced into. the other pipes. The valve’ ¢ being considerably loaded, fonces the “accumulating steam down into the rest of the pipes d, d, d. The air in these pipes recedes before the steam, and is forced through the tubes h, h, h, into the pipe m, m, m, whence it escapes atthe valve 7, and the syphon.k. ‘The water, con- densed in the whole of the pipes, passes also through the gubes h, h, h, h, into the pipe m, m, m, which has such a declivity as to discharge the water at the syphon &, into the hot well m, whence itis pumped back into the boiler. The * 334: History and ac- . count of the method of heat- ing rooms by Steam. HEATING ROOMS BY STEAM: . The whole of the pipes are of cast-iron, except sn, mt, iit; which is of copper. The perpendicular pipes serve as pillars for supporting the beams of the house, by means of the pro= jecting pieces 0, 0, 0, which may be raised or lowered at pleasure by the wedges p, p, p. The pipes are sunk in the beams about an inch, and are made fast to them by the iron straps q, q- Those in the lower story rést on the stones s, s, s, s, and are made tight at the junction with stuffing. The pipe in each story supports the one in the story above by a stuffed joint as shown at 7. The pipes in the lower story are seven inches in diameter; those in the higher six inches; those in the other two are of interme- diate diameters. The thickness of the metal is 3 of an inch. The lower pipes are made larger than the upper, in order to expose a greater heated surface in the lower rooms, because the steam being thrown from above into all the pipes, except the first, would otherwise become incapable of imparting an equal heat as it desoends. Thereis no necessity for valves opening inwards in this apparatus, the pipes being strong a to resist the pres- sure of ‘the atmosphere. The cotton mill is 60 feet long, 33 wide, and forr stos vies high, the upper being a garret story. In the engraving five parts out of nine in the length of the building are only shown. The apparatus will heat the rooms to 85° in the coldest season. It is evident that, by increasing the size, or the number of the pipes, and the supply of steam, any degree of heat up to 212° may be easily produced. It may even be carried beyond that point by an apparatus strong enough to compress the steam; this, however, can seldom be wanted. At first it was objected to this construction, that the expansion of the pipes, when heated, might da- mage the building; but experience has proved, that the ex. pansion occasioned by the heat of steam is quite insensible.* The * Certificates from Mr, George Mackintosh, and Messrs. Henry Monteith, Bogle and Co. of Glasgow; Mr. George Houston, Messrs. Robert Hodgart and Co. Messrs. John Fife and Co, and Mr. John M‘Naught, of Johnstone; Mr. James Boyle, manager for Messrs. M‘Farlam, Black and Co. at Gryse-Mill; also from Mr, CALCULT. The memorialist thinks it would be improper, in addrés- sing so intelligent a body as the Society ef Arts; &c. to ex- patiate on the various economical ‘purposes ‘to which the principle, which he has been able but imperfectly to unfold, 335 Experiments} ‘and observa- tions on urine; EC. may be applied. In abler hands it may be found suscepti-: ble of improvement, which he cannot anticipate. NEIL SNODGRASS. LY, Experimental Inquiry into the Nature of Gouty and Grae “velley Coneretions. By Tuomas eee MD. ROSA ree Tue urime of gravelly patients, when fresh wanted, nay, after standing many hours, inva temperature of sixty degrees, is relatively more acid than the healthy; sometimes _ as much so as the gouty; and frequently continues so, even after depositing its gravelly matter. An exception to this, however, sometimes occurs in gouty habits;. theix urine depositing copiously this acid substance, and yet manifest. ing no.increased, but sometimes rather decreased acescency ; for, with them, a considerable diminution of the quantity of the usually excreted super-acidulated phosphoric salt often takes place, as shall be fully explained upon another occasion. , Having premised these observations, it is now time to consider what effects acid substances are. productive of, when mixed, out of.the body, with this very complicated liquor. And here, to prevent repetition, I will observe, that that generally used, was rendered fresh in the morn. ing, in the quantity of from three to four ounces, (unless otherwise specified; ) being that most easily retained at one time in the bladder. The quantity of acid extremely Mr. William Kerr, for the Lochwinnoch Spinning Company, con- firin the utility anc success of Mr. Snodgrass’s method, and attri- bute to him the credit of first applying steam to the purpose of heating manufactories. * Extracted fram a longer Memoir in the Irish Transactions, BBS.’ td small, 336 Experiments and observa- tions on urine, &Ce CALCULI emall, for obvious reasons, and seldom increasing its aces- cent properties (as ascertained by the usual tests) beyond. what frequently occurs, in the urine of those who use acescent. drinks, or are afilicted with gout or gravel. A standard quantity was always laid by for comparison ; and the temperature from sixty to seventy-five degrees, being in autumn, 1799. And to begin with the vegetable acids. Exp. 1. To four ounces of \the urine of an adult, was added one drachm of common acetous acid, which (like every other acid) caused no immediate change in it; but, in a very short time, and before it cooled down to the tempe-— rature of the atmosphere, some extremely minute shining spicula, observable only by a lens, were seen floating. in it: these gradually increased im number and size, began t te reflect the light, and, from being perfectly transparent, ‘soon became ea, to settle upon the usual cloud, or nubecula, which now began to. form, adhere to, the sides of the glass, and partly fail to.the bottom, in. the shape of small bright red crystals. In the standard, after twelve hours, nothing more observable, than the usual nubecula ; nor was there any sign of crystalization, or ree of uric acid, even after twenty-four. ; Exp. 2. To: the same quantity of adult urine, were added one drachm and half of acetous acid, which caused ‘a More copious separation and crystallization ef this sub- stance, with the foregoing appearances.. None observable _ ‘in the standard after twenty-four hours. Exp. 3.. To four ounces of urine of a healthy child, who never was observed to.pass gravel, and of the usual -legree of acidity, was added one drachm of acetous acid, -which soon caused an evident and copious separation of “erystallized' uric acid’ The crystals were, however, not quite so coloured ;: the urine of childrén not being so muck impregnated with the urée, or colouring matter. No such appearance in the standard after twelve hours or more. Exp. 4. "To four ownces of adult urine; rendered very soon after a tea breakfast, and nearly in a state of wrine . potus, was added one drachm of acetous acid. After three hours, a crystallization of minute sandy particles took peer None i in the standard, even after three exh spin \ = CALCULI. 337 Exp. 5. Thirty drops only, of acétous acid, were Expériments added to four ounces of the urine of a gouty. patient, * Vid. p. 10. Inaugural Dissert. Exp. 7. 4 Vid. p. 10 & 11. Exp. 8. { Vid. p. 6. Exp. 3. Inaug. Dissert. § Vid. p.8. Exp. 6. || Vid. p. 28. Ex: 20, You. XVI.—May, 1807. 2E was 3b# Effects of opium on the kiving system. ON ‘OPIUM. was stupified and paralytic, in 20 minutes convulsed: after 40-minutes, voluntary motion had ceased: after an hour and ten minutes it was dead and the irritability in all- the. muscles was destroyed. xp. 8.* Thirty drops were injected into. another frog, after the removal of the heart; it lived an hour and 15 mi-. nutes, and after death the irritability was exhausted, | Eap. 9.+ Twenty drops were injected into a third: It. lived an hour-and twelve minutes, and the state of irritabi- lity was the same as in the preceding. Does the Quantity of Opium sufficient. to occasion Death, effect this by inducing, a Change,in. the Condition of the. Blood 2 Exp. 10.¢ By,some, former experiments, . wa, 17 and 35, § it had, been found, that. 33,drops of. the solution of. Pe aa injected into the.jugular vein .of a rabbit would oc- casion death in the course of a few minutes, and exhaust the irritability of the muscular fibre. Another rabbit was. selected; and 33,drops.injected into:the.crural vein; no other effect, resulted. from this but some degree of stupefaction. Twenty-six minutes afterwards 33 more drops were injected into the.crural;vein-of the-other limb. . The.animal in a short time became morelanguid, but was. not conyulsed; its pulse was rendered more slow and feeble; , at.the period: of, 36.minutes from.the injection into the first crural vein, Seven hours from the first injection, the animal was. con- valescent, and the day following it fed as usual. The occasion did not offer to make a computation of the quantity of opium which would be necessary to killa rab. bit when introduced by a crural vein, but the omission of this does not detract from the: force of the evidence which the above experiment:supplies; that the cause of ‘the death of the animal, when'the solution is introduced; by the jugu- lar. vein; mustarise from some other state, than: a change: in the condition of the blood, and that the effect of opium, # Vid. Inaug. Dissert. p. 29, Exp, 21. + Vid. p.30. Exp. 22 t Vid. p..74. Exp. 4& - —§ Vid, p. 20 & 55. must ON oPrunt a i 355 must Pees been extended over the entire aati ‘ie tabs EReeG of means than the circulation; for, what reason can be given eieadoolings why the mass of fluids aie not be altered, when the solution was introduced by the crural as well as by the jugular vein ; but. upon the other theory, the solution of this difficulty is easy, and accords with the whole series of exa periments. * The life of arabbit cannot be sustained a minute without the action of the heart ; when the solution of opium is in- jected into the jugular vein, it is applied to the inward sure face of the heart, mixed with a very small quantity of blood, and can then exert effects upon that organ as instantaneously as if the heart was immersed in it, as in experiment 2d +,. theaction of opium being thus directed against the irritable fibre, the exhaustion of that part would immediately succeed, of course the animal must die; but when the same fluid is. injected into the crural vein, it does not reach the heart until it has been mixed and diluted with a very considerable portion of blood, so that no quantity of blood which the heart could contain during one period of dilatation, would be impregnated with any great quantity of the solution of. opium. The consequences therefore, which followed from the injection of opium into the jugular vein, supposing . that it acted immediately on the heart, could not in this in- stance he expected to take place. Does Opium act upon the Nervous System ? Exp. 11. + A triangular piece of bone was taken from the cranium of a frog, and the dura and pia mater removed; eight drops of the strong solution were injected upon the brain ; a few drops were lost. In one minute the. animal was convulsed, in three minutes it was dead. On exa- mination the irritability in every part of the voluntary muscles was destroyed, neither compression of the nerves. nor mechanical irritation could excite any contractions in them. The heart had not lost its motion. _ ™ Vide Inaug. Dissert. p. 119. Note C. t Vide Inaug. Dissert. p, 17. Exp. 14. # Vide Inaug,. Dissert. p.49. Exp. 29. 2E¢ Mpeg 357 356 Effect: of opiumen the’. living system. ON OPIUM. e95 12. Jn another experiment of the same kind, the animal was immediately and generally convulsed, ha was dead in one minute. When the heart was exposed it was found contracting 42 times ina minute. The irrita- bility of this organ was not lost until three hours after. Exp. 13+. A portion of the cranium of a rabbit was elevated in like manner, and forty drops injected on the surface of the brain. At first the animal appeared lethargic and tottered. After ten minutes it was violently con- vulsed, and in the space of one minute and an half more, was - dead. When the thorax was opened the heart was found contracting with considerable force. The irritability was exhausted in all the muscles sub- Bervient to voluntary motion; they were repeatedly ir- ritated, but in vain. In these experiments, it is clear, that ¢ opium has a very powerful and instantaneous action upon the brain, that it is diffused over the whole nervous system, evinced both by the general convulsigns preceding death, and the total consumption of irritability in the volatile muscles, and which was equally as complete as if the opium had been applied immediately to the parts themselves. It was next examined, if when opiam is introduced into some other organ, its effects are extended by the nervous system to distant parts, ; Exp. 14i. All the parts as near as possible to the pelvis of a frog, on both sides, were divided, leaving the is- chiatic nerves uninjured. These were afterwards secluded from the air, by the divided edges of the skin being drawn together by slender threads, Three frogs. were. experi- mented upon. nt ohh ; Twenty drops of solution were injected into the stomach of one frog. The animal lived four hours after. On examination after death, the irritability was destroy- ed in all the voluntary muscles. | Into another frog thirty drops were SPE After six tecn minutes the animal was convulsed; the extremities below the knee which had no communication, with the * Vide p. 50. Exp. 31. © + Vide pe or: Exp. 33. t Vide Inaug, Dissert. p. 59, Exp. 38—-39, superior Tes ON OPIUM. 357... iy . ot superior part of the body, except by the ied ischiatic Effects of : nerves, were likewise affected by convulsions, and in two Doig ss hours and ten minutes the animal was dead. The ligatures which united the divided edges of the skin of the thighs were then separated, and the ischiatic nerves exposed; they were compressed; the compression of the herve on one side, produced a slight contraction in one of the muscles in the lower part of the limb, -but when repeated, no contraction followed; the Ui ateaatlad of the nerve of the other limb, occasioned no contractions. The irritability in all the other muscles was exhausted. Into a third frog, prepared in like manner, forty drops were injected: after fifteen minutes the animal was con- vulsed; after the space of two hours it was dead. Com. pression of the nerves did not excite the least motion in any of the muscles beneath, and when the skin was removed, the application of salt was equally as ineffectual, not the slightest degree of contraction was rendered visible. “""* _ From the event of these last related experiments we are instructed, that the effect of opium is extended to the most distant parts of the body, althdtigh the only communication, which remains between the extreme parts and the body itself, is by the continuif¥ of nerves, and these palpably not in a state best adapted to convey impressions. It yet remained to be examined if by ahy other com- munication the effect of opium could be extended to distant parts, if the supposed integrity and indivisibility of the irritable principle was capable of doing it. | Exp. 15*. The spine of a frog was divided above that part from whence the nerves issue which supply the inferior extremities ; care was taken not to wound any other part. After this operation, the muscles of the inferior extre. mities retained their irritability, and though the animal had Jost the power of voluntary motion in them, it had strength to drag them after its body. Into the stomach of a frog thus prepared, forty drops of the solution. were injected ; seventeen minutes after, all the parts of the animal above the point of the division of * Vide Inaug. Dissert. p. 62. Exp. 42. the’ 358 b at bee, Effects of opium on the living system. ON OFIUM. the spine, were violestly convulsed, and in one hour and forty minutes the animal was dead. ’ The upper part of the body was then separated from the lower, at the part where the spine had been divided, and the following was the state of irritability in the different parts.’ ‘ To the muscles of the breast and those of the superior extremities, salt was applied, but without exciting the least contraction or motion. The ‘iliac nerves below the point of the division of the spine were compressed; vivid and frequently repeated con- tractions were excited in all the muscles of the legs and thighs. This experiment was repeated several times and invariably presented the same result. All the muscles of the body above the point of the division of the spine, lost the irrita- bility; on the contrary, below the point of division, the irritability of the muscle remained unimpaired after the death of the animal, as was rendered evident both by the compression of the nerves and the application of salt. * To examine these circumstances a little more minutely, another experiment was made. *"Exp. 16*. The ischiatic nerves were divided on both sides in a frog, near their exit from the pelvis; this opera- tion does not render the limb entirely paralytic. The animal still possesses a voluntary power over the muscles of the thigh, in a-considerable degree: The upper point of the lag is rendered nearly paralytic, the lower point of the leg and feet are rendered entirely paralytic. “Into the stomach of a frog, thus prepared; thirty drops of the solution were injected; after twenty-one minutes the animal was convulsed; the convulsions extended to the thighs; the legs and feet were not in the smallest degree affécted by convulsions. In one hour and eighteen minutes, the animal was dead. . The application of salt to the inferior extremities, the lower joints of the legs and feet, produced rapid and fre. quent contractions; the muscles of the thighs at first did * Vide Inaug. Dissert. p, 66. Exp. 44, 2) ON OPIUM. “359 mot contract, but after salt had been applied some time, Effects of opium on the feeble contractions were excited. The salt applied to the living systema. muscles of the superior extremities and to those of the breast and back, was incapable of exciting the smallest fegree of contraction. {In this manner I submitted the experiments and opinions of the Abbé Fontana, to an accurate investigation, and I did not draw conclusions different from his without the conviction that the experiments which I have related were carefully made and many times repeated, and in the pre- sence of those whose bias led them to favour the opinions of the Italian physiologist. 1 shall therefore conclude this -part of the paper, with a general enumeration of the facts which have been ascertained. The first series of experiments proves that opium applied to the muscular fibre (the heart) exhausts or consumes, the ‘irritability of that organ. Vide Exp. Ist. 2d. 3d. and 4th. The second series of the above quoted experiments proves that the effect of opium is transmitted to distant parts of the animal body, when the agency of the cireulation is both withheld and destroyed, and in as rapid a manner as when the circulation of the blood is entire and vigorous. fe... Exp. 7th. 8th. and 9th. _ The third proves to a certain extent, that opium either does not exert any immediate action upon the blood, or that this fluid is an insufficient medium to convey it to distant parts of the system. Vide Exp. 10th. The fourth series proves: that the effect of opium is directly exerted upon the nervous system. Exp. 11th, 12th, 13th. That in proportion to the unity and integrity of this system, the effects of opium are extended to distant parts. Exp. 8th. and 9th. That where this integrity is only partial, the effects ave only partial. Vide Exp. 16th. That where the iutegrity is interrupted, the effect.of opium ‘is interrupted. Exp. 15th. And. finally, that the wna et indixise proprietas of irritability is inadequate in any degree to extend or communicate the effects or operation of the above-mentioned power *. VI. On * In the dissertation which has been so often quoted, the above experiments will be found oe by many — the tendency 2 of 360 Observations and enquiries respecting the improvement of poor soils, published by Harding, St. James's $treet. IMPROVING POOR SOFLS. On the Methods of improving Poor Soils, where Manure cannot be had. By Joun Auperson, M.D.* By soil is generally understood so much of the earth’s surface as has been acted upon by the sun and air, and im- pregnated from time to time with the result of vegetable and animal decomposition; but, as some plants will grow where no such impregnation has taken place, we shall con- sider this as mould, and define soil, a compound of certain proportions of the simple earths, of which Naturalists reckon six or seven; and as three of these generally pre- vail, it will be quite sufficient for my purpose to note, that these three are, chalk, flint, and clay. With chalk and clay every person is acquainted; and the common mede in which flint affects the agriculturist; is in the form. af: sand. All writers and experimentalists have agreed, that nome. of these earths will, separately, answer the purposes of which yerge to the same point, In that, the, general criterion which was established to denote the influence of opium, was founded on the observation of. convulsions preceding death, and the loss of irritability in the muscular fibre after death. The quan- tity of this remaining was denoted by fhe frequency and strength of the contractions upon the application of common salt. It was, after many trials with other substances, found to be the most gertain and effectual test. The manner in which salt produces this effect is no less beautiful than singular. Jt does not so much appear to excite a.muscle to contact, because a certain portion of irritability is present, as it appears to bestow irritability, if this principle is not too much extinguished and the vitality gone. A muscle which is incapable of contracting on the application of a mechanical stimulus, and is relaxed and pale, will, on the ap- plication of salt, exhibit very frequent and strong contractions, assume gradually a beautiful florid colour, and will then become obedient to other stimuli, to which before it was insensible. Thus jt will ’be found to be a better restorer of irritability to the musculay fibre, than muriatic acid, related by Hymbolt. — * Extract from a Memoir read in the Holderness Society, and agriculture ; IMPROVIN@ POOR SOILS. 361 agriculture; but that, when properly mixed, they certainly Observations ‘do support the roots and®add to the growth of plants; and ore ei according to the best information on the subject, if taken impsovement generally, the soil, when divided into eight parts, ought nage ge to consist of the following proportions ;—three parts of ‘clay, three: of chalk, and two of flint, in the form of sand; this last admitting of great variation with respect to its fineness or coarseness, according to the nature of the climate *. ne Many plausible reasons have been assigned why this admixture of the earths is necessary for the purpose of forming a good soil. First, a sail consisting entirely of clay, would not part with its water sufficiently; chalk would part with it too fast, and flint would not retain it -atall. Secondly, there are many of the plants we wish to cultivate, whose tender fibres are not able to penetrate clay; others that will not be sufficiently at rest from the loose and changeable nature of sand; and others that can- not act upon chalk +. If, then, the fertility of soil depend upon the due ad- mixture of the various earths, we may safely infer, that its sterility, or poverty, proceeds from the want of that com- bination. If land be barren when consisting of only one species of earth, its poverty will be in proportion the super. abundance that the soil possesses of that species, let it be flint, clay, or chalk. _ Experimentalists having then agreed, that a due mixture of the earths is necessary to form a fertile soil, and that barrenness proceeds from a want of the proper proportion, we see the necessity of being precise in our description of the soil we call barren. * These proportions will differ according to the quantity of rain that commonly falls in any'given place. I need not here enter upon the reasons why more rain does fall in one place than another; the fact is indubitdble, and I recommend the placing rain-gages in different parts of the country, in order that, by com- paring the result with the experiments now carrying on in other countries, we may be enabled to say what it the best proportion for this district. + See Kirwan, on Manures. if 362 Observations and enquiries respecting the] improvement of poor soils. IMPROVING MOOR $oILs. If I am asked how to improve a certain field, F should immediately wish to. ascertain what is the nature of its soil; in which kind of earth it is deficient; and in what it superabounds. If it be all clay, its proportion of chalk and sand must be added; and, where these cannot be had, substitutes may perhaps. be found: stiff clay soilis made more open, _in some countries, by burning portions of it in heaps, and then ploughing the hardened earth into the land. If the soil be sand, a frequent source of barrenness in different parts of Suffolk (where I have seen whole acres of barley blown away,).then clay becomes useful, and mar] the best possible ingredient*. An ingenious man, having obtained a grant of some -waste sandy land, which, till then, had been wholly un. — | occupied, was allowed to enclose as much as he could cultivate. He found near the foot of a hill a stratum of clay, with which he covered, the first year, am acre of sand, and then sowed it with grass seeds; this succeeding, he followed up his plan year after year, till he formed a complete surface of grass on many acres,—which, ploughed up last year, produced him nine quarters of oats per acre. Thus land, which, but seven years ago, would not have — maintained a single sheep, became fertile, and of consider, able value +. These premises being granted, and the facts established on the authority of many and repeated experiments; let us see, if any theory can be formed to account for the cir- cumstance, why a mixture of the earths should be neces- sary for the purposes of agriculture. The changes which take place in combustion, and those changes which constitute or exhibit animal and vegetable life, have often been compared: Food which supports fire, (as oxygen) is well known to Ye to the support of * Comtivn marl contains from 66 to 80 parts of pure chalk ; the remainder is in various proportions pure earth of alum and silex. Kerean. + This system, ona miuch larger scale, has been pursued by one of the most intelligent farmers in Suffolk, Mr. Rodwell, for which he obtained 2 medal from the Bath Agticultural Society. life ; IMPROVING, POOR SOILS. ife; and their products are in many instances the same eG carbon.) _ Now, in.order to illustrate the present sub- ject, 1 would carry the comparison furthcr than it has hitherto been done, and I would draw an inference by analogy from the process of fusion, and shew how re- quisite it is to make a due mixture of earths for the support of vegetable life, from the necessity there is of mixing these very earths in certain proportions, in order to render them capable of being acted upon, so as to be chemically eombincd, by means of fire. If I put pure clay, chalk, or flint uta crucible, and, place it in the hottest part of a furnace, no alteration or : change takes place; it will indeed lose the water or air that was attached to it, but the earth will remain the same, for it is perfectly irreducible; if, however, I mix them in certain proportions, and then apply the same degree of heat, they will liquify, continue in a fluid state (so long as the fire is kept up) and their particles, intimately com. bined, will form a mixt mass with properties distinct from each in its simple state. Now the operations of vegetable life resembling, as we said before, the chemical processes of combustion, may not a due mixture of these earths, when presented to the mouths _ or radicles of plants, render them equally capable of being absorbed, and converted by the action of the living principle into food, as they are of being fused or rendered liquid by fire? And thus am I not justified by the analogy, to draw this conclusion, that, by such an union plants - derive their nourishment from the earths ?—for, if the con- tact of these different particles of earth be alone necessary to enable the fire to produce the wonderful difference be- tween the state of a fluid anda solid, itis difficult to be conceived, that the principle of life, so analogous to fire, should be able to exhibit similar effects, in similar cir- cumstances ; and, taking advantage of the state of the earths, when thus duly proportioned and mixed, be able to absorb and convert them into nourishment? We see also from this theory, the philosophy of ploughing, harrowing, hocing and rolling, operations indispensably necessary to a good 363 Observations and enquiries respecting the potent of poor soils. ~ 364 Observations and enquiries respecting the improvement of poor soils. a e IMPROVING POOR SOILS. good system of husbandry. Whenever plants have drawn from the soil, in the neighbourhood in which they are placed, all the materials that happen to be duly mixed, they are no longer capable of thriving, until, by a new operation, more particles are brought into contact with them. This has been sufficiently proved by persons who are in the practice of horse-hoeing, and is in effect the very object of those repeated ploughings which are per- formed with the view of preparing the ground for the reception of fresh seed. By this theory we see why marl becomes so admirable an addition to some soils, as to he even called a manure. Marl is formed by the deposition of clay *, and chalk from water, which, during floods and rains, has held these earths suspended; and which component parts are so intimately combined, as to be capa- ble of being acted upon by plants. Marl I apprehend will be found in this neighbourhood at some future time, when repeated borings shall have given us the exact state of the different strata of this district +. If I shall have the good fortune to establish this theory, we shall not have occasion to seek for the reason why chalk renders clay productive, by supposing that the latter contains an acid +, which the chalk absorbs, for that would be begging the question, as no such acid has been proved to exist, nor shall we have any difficulty in ac- counting for the different opinions of authors upon the value of lime, chalk, &c. as improvers of the soil; for, when the lime has exerted all its powers as a manure, (that is, such of it as has suffered decomposition through the medium of water, in which, till it recovers its air, it is soluble) the remainder being mere chalk, mixes with the soil, and, as itmay happen, will be useful or not accord- ing to the nature of the ground itis laid upon. Lime may answer to the farmer as a stimulus, but it can only improve the soil ta the land-owner, when it is laid upon clay or * All clay contains a portion of sand. + Vide Kirwan’s Mineralogy. t See Home, Mills, and others. sandy IMPROVING POOR SOILS. 365 ‘sandy soil: and in this view, chalk, in an equal state of Observations fineness, is as valuable as lime*. and enquiries respecting the We must never forget, that plants contain a living prin- improvement of ciple, that the action of this principle seems to be analogous to P° soils. the power which fire has of altering the arrangement of the par- ticles of matter ; ofelevating some into the form of gas, and of rejecting others ; and that the final cause of life, in every indi- vidual, is to bring together such particles of matter, as, when duly acted upon andassimilated, will constitute the essence of each particular living being. Thus, from the same nourish- ment do. different living powers produce totally distinct matters, only by new arrangements: and in his laboratory the chemist, from various and different proportions of the _ same ingredients, can constitute and produce results, more different, in their properties and appearances, than any two species of plants or animals. All the alterations which the earths undergo when by heat they run into fusion, become fluid, or rise into vapour, are produced by operations very similar to those of di- gestion and chylification in the body. Every particle of matter, by one process or another, is capable of being con- verted into aeriform fluids, which, in rising from the sure face,, meet, intimately mix and form new compounds. The same may be affirmed of composts: the intermixture of various substances produces decomposition, particles, formerly united, are separated, and new arrangements take place. * The nature of the lime employed must be attended to ac. cording to the nature of the soil to be,improved.t¢ Chalk, when burnt into Lime, contains from 5 to 10 per cent. of sand or clay, whereas some lime-stones contain from .50 to 80 per cent.; some also contain Magnesia, which according to Mr. Tenant, Philos, ‘Trans. is not only not useful in agriculture, an improver of the soil, but hurtful to vegeetable life. Magnesian limestone may be discovered by the slowness with which it dissolves in acids; and it may be easily detected in chalk, by adding a sufficient quantity of the vitriolic acid, which, uniting with the magnesia, forms the bitter purging salt very distinguishable by its bitter taste. + This opinion of Mr. T’s, is controverted, by Mr. Headrick. See Farmer’s Mag. 5 . All 366 Observations and enquiries respecting the improvement of poor soils, IMPROVING POOR SOILS. All the products of nature seem “destined to perpetuat change and alteration; and the fibrous roots of plants appear intended by providence to produce the first stage in the transmutation of inert matter into life. Thus, by de- composition and absorption, earth becomes vegetable ; vegetable matter is no sooner decomposed in the stomach of animals, than it is capable of being converted into animal matter; and when farther purified by the delicate organs of the human body, reaches the utmost perfection of created intelligence. * de Having thus generally stated the necessity of a mixture of earths, in the formation of a good soil, and pointed out the reason for that necessity, I shall beg leave to particularize a few things more in answer to the question. Tt has been a commonly received opinion, that oil is the _ principal food of plants; but oil can no more enter the fine vessels of plants, than any one of the simple earths; it must . therefore be decomposed and resolved into its elements, as well as any thing else. Oil may, and probably does, contain a very large portion of the substance which constitutes the - chief food of plants in certain stages of their growth ; but it must be decompounded to produce digestion, in the same ‘im manner as we have proposed in the admixture of the different earths. Alkalies and lime will render oil capable of mixing very intimately with water; and we are thence led to con. clude, that they may contribnte to render it more digestible, and thus capable of entering into tbe composition of the plants destined to be nurtured. This doctrine may be farther illustrated by the process which milk undergoes in the stomach and bowels —Milk does not enter the lacteals of animals; but must undergo decomposition, and be digested, as well as any other food, _ before it can serve the purposes of nourishment. There are however many other things to be done, before barren soils can_ be, productive, and which may be be done where the due admixture of the earths is not to be obtained. fi are the a God, 5 dane ae oh the dust af the e ground Genesis i.'7. « For thon exist’st on aane a ruchicanals grains that issue out of dust.” - .». . SHAKESPEARE. . There IMPROVING POOR SOILS. 367 Theré dre various processes found adapted to pasticular Observations soils, the introduction of which may reward the industry of 2>4 enquiries | respecting the the husbandman. improvement . Ist. Thus the wolds of this country have been enriched of poor soils. by the cultivation of saint-foin, and tons of hay are now produced, where one blade of grass could scarcely have been found a few years ago. @ndly, Thistles, which are capable of deriving nourish. ment, and growing toa large size, where no other plant can exist: these by the exuvie, or remains they leave, and. the protection they afford to other plants and many animalculz, tend to ameliorate the soil; but, whether they should be suffered to grow to a crop, and advantage taken of their product, or ploughed in as manure, is a question which I shall not agitate at present. 8rdly, The cultivation of spinach may be recommended as calculated to answer the same end, the prickly kind being the hardiest is to be preferred. Succulent plants im- poverish the ground but little, because they derive a great part of their nourishment from the atmosphere, as may be easily proved from the alee tribe, which will lie out of the : ground fora great length of time without being hurt, draw-. ing their nourishment from the atmosphere alone; and_ certainly these fleshy succulent plants, when ploughed in, will afford a very considerable supply of food for more useful plants *. 4thly, Buck-wheat also, and fumitory, a common weed upow chalky soils, may be converted to every useful pur- poses as a stimulus to vegetation; for the latter, when burnt, affords an uncommon quantity of the fixed alkali, so well known to be a most powerful stimulus to the growth of plants; and as the poorest soils may, by a particular management in the use of stimuli, be made productive, so. an alternate crop of such plants with corn, seems to be an eligible mode of cultivating pout soils, where lime and matiure are not to be had+. * « All succulent plants make ground fine and of a good “quality.” Vide Biberg’ Cconomy of Nature. + Inthe 23d Volume of the American Transactions, there is'a” paper on the cultivation of the eastern shore Bean, for the express purpose of being ploughed in as a manure. 5thly. ee Observations _ and enquities respecting the IMPROVING POOR S sorts. 5thly, The planting forest. trees, as tending to. defend | fhe more valuable plants from the i injury they are "exposed. | to in a poor soil, is an object well worth attention more, — ‘» “particularly on grass land. Some author, in the Academy of Sciences, has proyed, that land exposed to a long current; of. wind, which blew over a Jarge tract of barren waste, would produce nothing bit poor grasses, so long as it e+, mained thus.exposed; but, when this current was broken by a few hedges and plantations of forest trees, it hecame capable of propagating and rearing the most useful and pro- lific plants. Perhaps the atmosphere attracted by the trees, . parts with its electrical matter, which has been found highly conducive to the growth of plants. The agitation given to. : the air, when driven against the hedges and trees, may dis. pose it toa decomposition highly favourable to its yielding Rourishment; and on this principle, I apprehend, that in j districts where the air is partially obstructed, by hedgés and trees, ‘it always tends more to the ainelioration of land, than where stone walls and mud fence are employ ed. 6thly, Planting oziers, on wet land, is another mode of answering the end proposed in the question. “Lands not “worth half-a-crown an acre on the side of the Trent, haye been planted with oziers, at the expence of four pounds per acre, and since let for four guineas an acre per annum. » 7thly, One source of barrenness in soils is. the: presence of the calx of iron. The calx or rust of iron may be known by the redness or blueness it gives to most soils, with ‘which it is incorporated. It may appear extraordinary to many, | that this iron should be the result of vegetation, but the | fact is incontrovertible*. I have reason also to believe, from observation, that some trees and plants,. are more “disposed than others to produce the mineral earth; and it behoves.. the improver of the soil to ascertain, what. these plants and trees are... Of. trees, the willow tribe, and alder; amongst. plants,. the whole order, of rushes. and . above all, mosses, most assuredly abound in. iron, and. ought never to ‘be rate to exist on cultivated land, * Vide Thompsons Chienistry,, Val, W. page 228; Chapt Vol. iif. page 170s © 7 * Segall Bis ire IOTah? Pet Yo ene 8thly, IMPROVING POOR SOILS, 369 Bthly, The action of water upon soils in general ought pee pit ly not to be overlooked. Lying long upon the ground, it respecting thé certainly tends to the destruction of those plants we wish to of ad a cultivate. Hence i in all countries ener] ran es should be resorted to, _to carry off the water, when its continuance would pro- duce this effect. ‘ But thousands of acres are barren for want of water; and there are few situations in which, if kept up in re- Servoirs, it may not be employed at aay with cot. siderable advantage. Im a yariable climate, and a cultivated country, like ours, all the water that falls might be employed in agricul. ture. In the present state of things, perhaps, the expence might be greater than the profit; but, should engine work be so far improved, as to reduce the price of labour, and be introduced into practical husbandry, it will then, ina ‘level country like Holderness, be no very difficult matter to place reservoirs and drains in such a manner, that a whole farm may be either drained or flooded at pleasure. The Chinese, who certainly’ possess the best cultiva- ted country in the world, are not content to make canals for the purposes of trade, they dig many others to catch the rain, with which they water their fields in time of drought; during the whole summer, the country people are busied in. raising this’ water into ditches, which are made across the fields; in other places they. contrive large re- servoirs, made of turf, whose. bottom is ‘raised above the level of the ground about it; and, ‘if they meet with a _ spring of water, it is worth while to observe how carefully they husband it; they sustain it by banks in. the highest places, they turn it a hundred different ways, they, divide it by drawing it by degrces,. according as. every one has oc« tasion for it, in so much that a small rivulet, well managed, sometimes carries fertility te a whole province +, * With a double-view, catch-avater drains, as they are called, eught to be formed, not only to prevent the low lands being flooded during violent rains; but, by keeping up the water, to preserve it to be employed, at a proper season, in irrigation. - + Vide Le Compt’s Letters. on China. via’ ~ Vou. XVI.—May, 1807. ar Con- rus 370" Obseryations in, order to find the best means of carrying off the water ; and enquiries respecting the improvement. of poor soils. IMPROVING POOR SOILS.” Considerable expence ‘has been incurred i in this countiy, but sufficient attention has no where been paid to the improve- ment of the soil, by the introduction of water for irrigation *. Great advantages, of late years, have been derived from “warping, along the banks of the Ouse, the Trent, and tlic Dutch river, where the water is let in at the flood tide, and suffered to rest, and deposit its mud, until the ebb. By ; this process, repeated twice a day aueite five or six summers, 4 new soil is formed, to the height of. six feet, which, in- the followiug spring will be firm enough to receive seeds, and in summer to carry an ox. Thus land, which was be- ‘fore’ only a peat bog, comparatively worth nothing, may be let for forty-five shillings per acre. ~The Dutch river affords the best warp, because it nearly empties its whole channel during the ebb, and consequently ‘contributes only the tide, there being very little back water ‘during the flooding season; and hence, too, dry summers: ‘are better than wet ones; for, when the freshes are out, the water, though muddy, contains nothing bat clay, ‘washed from the tops of mountains, and the banks of rivers ; ~ but the muddy water of the tide contains all the products ‘of the Humber, which consist of a large quantity of anima? matter, as well as various species of earths. An enterprising and spirited individual has’ proposed to warp the whole of several parishes extending over many thousand acres of bog, for one sixth of the land gained ; which he purposes to effect by cutting a general canal, Eons these parishes from the Dutch river into the Trent +. “9thly, * The whole of the low lands of Anlaby and Hessle might have been watered at pleasure, by keeping up the spring that passes: through Anlaby town; or, by boring and piping the springs that may any where be found, and which will rise, in most places within those parishes, above the surface, -+ The farmer, the land- -owner, and the public, have all been benefited by this improvement. ‘The farmer, by his industry and attention, has converted the most barren bog into land capable of bearing the plough, and of feeding an ox. ‘The landlord by only foregoing the rent during the time the land is under water, has been able in a few years to increase che value'of his property fifty fold. The IMPROVING POOR SOILS. Sil 9thly, Those whose lands border on the Humber, or the Observations Sea, may derive a further advantage from this vicinity, than pest ae what arises from mete irrigation. I have already taken improvement Some pains to point out the absolute necessity there is for of poor soils.” bringing the different carths into close union, in order to procure that decomposition, necessary to their being con- verted into vegetable life; the same doctrine is applicable to composts, and may now be extended to salt water. / Salt water consists of certain alkaline salts united to the marine acid, which form a neutral, not easily decom- pounded in common earth, and ectefipre not a very active manure. To obtain the greatest possible advantage from sea water, it ought to be decomposed, which may, in part be effected by adding to it gypsum, alabaster, or plaster _of Paris—a matter compounded of lime and the vitriolic acid. When this is well soaked in sea water, the vitriolic Acid will in time quit the lime, seize the alkaline basis of sea-salt, and leave the marine acid to combine with the lime ;* but in all these operations a large quantity of earth or soil should be compounded with the result, before it be applied as a manure, the salts being of themselves too ‘pungent, if applied to vegetation unmixed with earth. This method ought also to be pursued, when any composts _ are formed. 10thly, Sand is also capable of further use than what is merely pointed out by the foregoing theory. In Norfolk it is thrown into the yards and stables, to absorb all the moisture ; and the horses and cattle that are fed in the stalls, with cut grass or vetches, are bedded with it, in order that their urine may be absorbed and employed for the future amelioration of the soil. 11thly, The banks along the old or natural drains, which - The country at large not only obtains an increase in the supply of the food of man; but thousands of acres of the most noxious fens, prolific only in agues and remittent fevers, are by this process, covered with a. healthful appearance. * According to Berthollet, chalk is capable of decomposing sea salt, in the course of four years, and by that process, the natron of alkali is suffered to chrystalize in the Jakes in Egypt *. * Vide Memoirs. on Egypt. 2Fe2 hare ervations -enquiries ecting the rovenient ’ oor soils, IMPROVING POOR SOILS; have been formed by the overflowing of particwlar. tides, when the. Humber was not so well restrained within its limits as at present, are capable of being employed, to improve the soil. It is well known, that where the water first begins to deposit, there the best soil is produced; and, as these, banks have been formed by repeated. depositions of this kind, they consist, several feet deep, of ‘valuable earth, Ww hich may. be led away, and employed as a manure. | aR RE vt vA PPEN DIX, “IN 3 ans wer to those gentlemen in this Society, Mr. Presi. dent, who have said, there is no land in Holderness bad enough to grow thistles upon, J ask, is there no land that requires occasional fallowing? If this be allowed, then the’ question will be, whether the cultivation of thistles be, or be not, more advantageous to the land, or, pro- ductive to the farmer, than letting it lie fallow. Now. it haying been stated by such authority as. Dr. Withering, that * ‘thistles grow and flourish upon clays, where no ether plant can exist w ithout manure, and that, where they have grown, other plants may afterwards be. propagated, will not a crop of thistles be found highly advantageous to. the farmer? + For if they exist upon land; and draw none .«* Thistles, as the most useful, are armed and guarded by nature herself. Suppose. there was a heap of clay, on which, for many, years no plant. had ever sprung up, let the seeds of the thistles blow there, and grow, the thistles, by theirleayes, attract the moisture out of the air, send it into the clay by means of their roots, will thrive themselves, and afford ashade. Let now, other plants come, and ‘they will soon cover the ground.” Biberg’s (Economy of Nature, translated, by Stillingfleet. See also Ww ithering’s Botanical Arrangement. +.“ It is, probable,” says Parkinson,,..“‘ that. the idow-thistley were it properly cultivated, would become one of the most. fatten: ing plants the earth produces. Sheep, when in clovers, &c.. wil} feed L pon. it so greedily, as to eat the, very roots; pigs likewise prefer it to almost any other green, fod ; 3 Tabbits will. breed more speedily when fed with sow thistles, than.with any other food I: know IMPROVING POOR SOILS. ote none of thé common nourishment ‘from it, will not they, Observations and enquiries in a state of decomposition, be a valuable addition to sespectt 1g the nourishment, or at least prove a pow erful stimulus to more improvement valuable plants, which we may afterwards wish to cultivate bi ature) upon the same land. - . Itis not the chief end of the existence of plants, to bring dead earthy matter into a state of life? We know, that when there isa due mixture of the earths, any plant we wish to cultivate will thrive and produce this effect ; and that; if we add a Sufficient stimulus, or manure, then such plants will yield the largest increase; or even where there is not a due mixture, provided we can supply a large and repeated’ quantity of the stimulus that even there, they may. fora séason, be induced to make vigorous shoots and even perfect themselves. But in the case of barren soils, where this due mixture is not present, and where (as the question implies) thé stimulus is not to be had, itis the object of our’ enquiries to find out a plant that will grow, and either yield an immediate profit, or, by improving the soil, énable others more valuable to succeed in future. Now, as the soil immediately referred to is confessedly clay, and as thistles will grow on it, and leave behind them ‘such a quantity of refuse as will enable other plants to succeed, ought we not to recommend the cultivation of them on poor Jand, with the expectation that they will add more to the zoil than they take from it, and so lecome improvers. He > ae know be except dandelion, which is of the same nature, and is now sold in’ Covent garden market, to the breeders of tame tab- bits. A man of my acquaintance, who was allowed better skill - with stallions, than the generality of mankind, used to search for sow-thistles to give to his horse. We have a well-known and decisive proof of the nutricious properties of sow-thistles, in the. fat wether sheep, fed to an amazing size by Mr. Trimnel, of Bicker Fen, neat Boston, Lincolnshire, upon the fen land. This Sheep was bred by Mr. Hutchinson, in Hail fen, from a ram bred by Mr. Robinson, of Kirby, near Sleaford. He never ate any corn, oil cakes, Sc. but- fed wholly upon grass and herbage; being tarned with many other sheep into’ a field of clover, this sheep was at first observed to search for sow-thistles, and would eat no ether food whilst any of them could be found in the ‘part of ‘the © field 374 Observations and enquiries respecting the improvement of poor soils. IMPROVING POOR SOILS. It is an old farming maxim, that plants of the same species will not thrive successively on. the same land, for, where. one plant has died, another of the same species cannot live. This is the case with animal life, and with combustion, or fire; two processes extremely analogous | to vegetation *, Where .a candle becomes extinct (provided no fresh air be admitted) another cannot be lighted, and where an animal has died, another of .the same species cannot exist ; but other combustible matters may be made to burn, aa animals of a different species may, for a time, be made to live. Thus I would infer, that, where a crop of. wheat has grown, been brought to perfection, and died, there another crop of the same kind will not succeed; although ‘different kind of corn, pulse, or grass may. Now the reason why the former phenomena. take place, is partly by the abstraction or taking away of something from the air, necessary to the life or support of the first anima] or combustible substance, and partly, by the giving out something, which, (though inimical to the. individual that parts with it) is nevertheless, (so far from being hurt. ful to others) the very matter some kinds prefer. to liye upon. The same or similar processes may go on with plants; where acrop of wheat has grown, the materials for the sustenance of wheat may not.only be absorbed, but the situation in which it has lived and died, may be so im- pregnated win its excretions +, as to be inimical to ‘the life field, that was hurdled off successively a little at a time; when _the field was bare of thistles, his attendants gave him three times a day, from two to five pounds at a meal. This sheep, when killed, measured five feet from the nose to the tail, the rump or cushion eight and a half in depth, plate .or fore flank. of the same thickness, . breast end seven inches, one yard five inches anda half ‘round the collar, and weighed sixty seven pounds a quarter, avoir- -dupoise weight; the legs were estimated at forty pounds each, but if cut haunch of venison fashion, would bave weighed fifty pounds each; for which the proprietor, Mr. Lumby, was offered zwo shillings a pound; so'that the legs only would have brought ten ~ pounds: «ide Parkinsow’s Experienced Farmer. __ * Vide preceding Observations. of This theory may be exemplifigd: by. a. facty: iid, I have fre- IMPROVING POOR SORA: i 375 life of any future plant of the same species, although, as Observations we said before, not for any other kind, until, by a proper a Cea | succession, this very matter be atheaciell ind absorbed into pr asiblaersing the substance of other plants; and thus we are enabled to of poor souls. point out the obvious principles that govern those rotations, which the experience of all ages teaches. The great desideratum, or object of our enquiries, then will be, what are the best means of bringing together a fresh set of materials remaining in the soil? And, what is the succession best calculated to remove from the Jand, the dregs of former crops; or, what plants will best live and thrive where others have previously been cultivated? I know it is the general opinion of men of. experience, in this part of the country, that fallowing can alone effect the former, and it is the general practice to make the black and white corn suéceed each other, in order to effect the latter. Let us, however, enquire a little further. . I amy aware, that the fact (to account for which, 1 have ventured to frame a theory) has been denied: by authority *, long celebrated in agriculture ; I mean, ‘¢ that » heat -cannot be made to grow upon the same land, for two or three years ‘successively ;” and we are referred to an experiment made in a field belonging to Mr. Barlow, near York, -for the proof’ of the contrary; but what does the experiment ‘say?. It says, that ‘plants of wheat were taken fromia situation, in which they had stood the wintér, and trans. planted into a field that had grown ‘potatoes; had beén afterwards ploughed, harrowed, and rolled, and .wefe pricked down an inch deep, par nine tischics from each other ;” and, ‘* that it is ‘proposed to do the same fér several successive years, in order to determine the doubtful ‘point, whether wheat can be raised for a number of suc- “cessive years, upon the same land;”’ and, ‘‘ that, instead of letting the land lie waste, under a summer fallow, it may be made to produce a crop of cabbages, turnips, pease, beans, potatoes, or summer vetches, as preparatory to its _being planted with wheat.— Can this experiment militate in _ frequently observed; the fibrous roots of thorn, and many ‘other trees and plants, where they enter — or clay, leave. ages them an ochre, or irony mark. * Vide Dr. Hunter’s Cireylar Letter. : the 376. Observations and enquiries respecting the improvement of poor soils, IMPROVING POOR SOILS. the least against the doctrine here advanced? or does not rather go to prove the truth of it: for, isit not clear, that, in order to succeed, it is necessary by transplantation, to remove the plants froma soil, out of which they have al- ready extracted-a certain portion of its nutricious matter, and in which they have already deposited something ‘which might be hurtful, when they came to flower and seed ?* That the plan of transplanting wheat will answer I have not 2 doubt; it has long been practised by several gentlemen in Norfolk; and upon the’ principles here laid down and agreed upon, we can judge how it may prevent the necessity of fallowing, as it goes to prove what I have before hinted at if my theory, that, by sowing a summer crop of legumi- nous plants, such as pease, beans, vetches, &c. or. the useful roots, turnips and potatoes, every thing hurtful to the growth of wheat may be taken from the ground. This, however, will be perhaps as profitably done by substituting a succession of other white corn, instead of wheat, in a regular manner, From the foregoing, | then we are led to conclude, that, by attention to a proper mixture of the earths, in order to’ bring various particles into intimate union, by frequent new combinations, and by a succession of plants dissimilar in their habits from each other, we may so far improve agriculture, as to have yearly crops from such a soil as ours; and that it will be possible, in time, to bring every acre of ground in this district into an almost equal degree of. valuet. © : * Some warp land on the othier side of the. ue oyuautad wheat for seven years, successiv ely, without manure; . but, this only proves the possibility, that earth may be accidentally so well. arranged and-mixed, as to wie nourishment for along succession. , of crops. +. ‘There is.a practice, freeuent in Holderness, sshick deserves to be reprobated, and thet is, suifering stubbles to lie unploughed — after harvest. It appears to me a shocking waste of the valuable soil, to suffer it to be exhausted at the latter spring, in producing useless plants and weeds, The great object of agriculture, is to take advaniage of every circumstange, that can cblige the eapth to. produce only the profitable parts of the vegetable creation; to suffer the land, therefore, to support what xt present we know not the use of, is in the highest degree injurious and,impolitic. Vil. - “+ s - . oz - ~ hs » ay SNEUMATIC APPARATUS. Big LP A OMaTs Description, of an Apparatus for transferring Gisses over Water. or Mercury, -&¢: Ss the: REY. Sip aBAT AUSEIN» M. R. ‘ad Ae Pe difficulty of transferring g gasses. fae) one jar or re- Difficulties of ceiver to another without Joss, . or. mixture. atmospheric- on ee air, by. the ¢ common mode in. the pneumatic apparatus, must usual appara- have been ~ experienced often by. philosophical _ chemists, a And this difficulty is encreased when » VEER large j jars are. used, and when. the production, of gas. in them is inconsid- erable ; as when oxygen gas is obtained from. vegetables. exposed to light, or ‘from the. decomposition of- water. Otec the’small quantity, “obtained in. this manner, a portion is. often ‘lost in transferring it into a smaller jar for the purpose-~ of subjecting it to examination; and the result of the. ex-t periment is" ‘rendered uncertain, if the object be -to measure the quantity. In order to obviate this incony enience, I beg leaye to submit to the Royal Irish Academy the description’ of a small apparatus, which I have found to answer well, - and conceive may be admitted as a useful instrument into a philosophical laboratory. The principle part of this apparatus consists of two. pieces: A new appara of plate glass, with a hole of about half an inch diameter tusin which these glass drilled through each. They should be something broader, plates are ap- and about twice as long as the diameter of the jats used in Plicd to the . . mouth of the collecting amd transferring the gasses. ‘The holes should be jar- &c. disposed as in the figure. That in the plate (Fig. 1.), marked (a) should be nearly in the middle of the piece. The hole inthe upper plate (2) near the extreme edge. The upper plate is shorter than the under-plate, and its edge is grounded air and straight, so as to fit the edge of the third plate, which ‘is not drilled, and should bea square, piece cut off the second plate,as it is very necessary that pe two pti should be ofthe same thickness. The *. » Prom the Irish Memoirs, i806. length ITS Improved ap- paratus far transferring the gasses. PNEUMATIC APPARATUS. length of these plates together should exceed that of the under plate about an inch. It is rather better to. grind the polish off the plates with a little fine emery, as they. slide more equably over each other when so prepared. ~All the jars to be used with them should have their mouths ground on a flat plate with fine emery. Things being thus pre- pared, the transferring plates may be used in the following manner, particularly when the jars -for collecting the gasses are large. When the jars, inverted in ie usual manner in the pneu- matic trough. are filled with the gas in any proportion, the two plates (a and 4) are Jaid over each other in such a situa- tion,ttat their holes shall not coincide; they are then plunged into the water, and the plate (g) applied to the mouth of the jar, and that and the plate (4) being moderately pressed against the mouth, so that they shall not slip, or suffer any gas to escape, the jar together with the plates, is lifted out of the water, and set with the mouth: turned up.. In this position the jar is ready for yielding the gas to the jar into -which it is to be transferred. This last jar-is now.-to be filled with water, taking care not to leave any air in, it, and its mouth is to be closed by the third -plate.. It is then to be turned with its mouth downwards, and, together with the third plate on which it stands, is to be placed on that- part of the under plate which 1s not covered by the upper plate. The edges of the third and upper plate are placed as nearly as possible in contact ; and across them the snaall jar, filled with water, is to be slided till it rests entirely on the upper plate.. The hole in the upper plate is tobe filled with a few drops of water, and the jar is to be slided so as to stand over it. The upper plate,and the jar standing upon it, aye then to be so moved oyer the.under plate, that the. holes in each shall coincide. The water in the upper jar, as-soon as the communication is thus opened, will descend into the Jower or magazine jar,and be supplied with an equal bulk of gas from below at pleasure. When a sufficient quantity is transferred thus into the upper jar, it is pushed together with its plate, in such a manner that the holes shall no longer coincide, and, consequently, the communication shall be cut - off, ne upper jar is slided back upon. the third plate, and, PNEUMATIC APRBARATUS. - : 379 ua and, together with the plate, is removed in the same manner Improved.ape as it was applied. The mouth of the jar is turned upwards, ?” aa ee the _the plate removed, and the gas submitted to examination : gasscs. or, with mouth downwards, the small jar is placed on. the shelf of the pneumatic trough, as the experiment may re- quire. This detail appears tedious, but the practice is very easy. In this process there is, however, some danger of dis- turbing the lower: plate, by lifting it from the-mouth of the magazine jar, and so vitiating the gas by the introduc- tion of common air. To prevent this inconvenience, it is necessary to secyre the two perforated plates:to the mouth of the jar, and to each other, allowing the upper plate, at the same time. to slide freely over the other. .For this, purpose, it is necessary to fix ‘the plates, and the magazine jar,in a frame; which renders the use of .them very convenient, and not liable to accidental disturbance. ~The two plates ~u and ),as in, Fig. 1,, are ‘ey in the upper part of the frame: («) is fastened (// slides easily ‘over it.) The jar (d),is pressed up against the plate /«) by a moveable bottom (4), tightened by wedges or screws. The jar may be filled with water before it is fixed in the frame, and invertedin the trough; or the air niay be gen- erated in the jar, without the frame,and then, the frame being inverted ; and the platessunk in the water, the jar may be slipped into its place, and fixed there, which is the better way. The frame and jar are then. set upright, and the gas may be pacientes as before, mtn danger ar loss. or mixture. “By means of this apparatus, jars of any size may be used as magazines, with the inconvenience of being obliged to, in- vert them in large troughs. This apparatus, also,on a smaller esi may be nest in ‘operating with those gasses-which can only be confined over ‘mereiiry.. The joints of the transferring, plates .retain . very ‘securely any qaantity of mercury, provided the height of the ‘jar is inconsiderable, not more than three.or four inches, for ‘yeasons well known to experimental philosophers, And ‘small jars, with ground mouths, hold mercury. very well, when standing, without agitation, with their mouths down- wards, on ground plates of glass,.. The careful operator will, dia | however, 380 Improved ap- paratus for transfesing the gases. ~ PNEUMATIC APPARATUS. however, gently press them to prevent accidents. . This ap- paratus may be so far reduced i in size, that, ona. small sc le, all operations, on gasses. only to be confined over mercury, ‘may be performed with about four or five pounds of mer- cury: which may, in many eases, be an object of attention to the philosophical chemist. Fig. 1, (a) The under plate ; the dotted line cia the cir- cumference of the mouth of the magazine jar. (b) The upper plate. (c) The third plate; the dots mark the circumfer- ence of the mouth of the smal] jar. The small dark circle shews the eit of the holes. Fig. x. (a b ¢) The section of the plates, (as ‘i in ‘Fig. I.). (a) The magazine jar. (¢) The small jar. ' (P The dotted jar shews how the small jar is placed, together with the third plate (2), before it is ‘slided acrass the edges (g) of that and the upper mye Fig. 3. (abe) The plates as before, but fixed i in. (}) The frame.» | % (@) The lower or magazine fans (as wedged up against the under plate, by (k) The moveable bottom. (e) The small jar to be filled with gas from the lower jar. Fig. 4, A small Apparatus for opperating with Mercury. (a bc) The plates as before. (2) The small jar, four inches high, rho ati saben rim, by which the lower plate may be confined to its mouth, together with a frame in which the upper and third plates may slide. This frame may be made of hard wood, of ivory, or of iron. (g) A section of a wooden box, to hold as much mercury as will cover the plates and frame, and - admit the bent tube of (I) MINERAL BASON. 381 ¢) ‘A small retort or vial, with a bent tube, for Impreved:ap->" generating the gas which passes through the hole ee the of the plates. gases. (m) A. small spirit lamp. (a) A tube, fixed so in the box, that the mercury, descending from (d) as the gas is generated, shall overflow, and ‘be received in a cup; with which small jars may be filled for transferring. Vit. Description of the Mineral Bason in the Counties of Monmonth, Glamorgan, Brecon, Carmarthen, and Pembroke... By Ar. Epwarp Marrin.* "Pe imegutar oval. line, delineated on the annexed Mineral basou map.t-shows nearly the inner edge of a limestone bason, in i SouthWales. which all the strata of coal and iron ore (commonly called Iron Stone) in South, Wales are deposited ; the length of this bason is upwards of 100 miles, and the average breadth in the counties of Monmouth, Glamorgan, Carmarthen, and part of Brecon, is from 18 to, 20 miles, and in Pembrokeshire only from 3 to 5 miles. 2, On the north side of a line, that may be drawn in an east and west direction, ranging nearly through the middle of this baat, all the strata rise Rrupdy northward; and on ¥ Phil. Trans. 1806. + The outline on the. map given in the Transactions (but not copied in our Journal) begins from the N: E. corner of St. Bride’s Bay, and proceeds by Haverford West, across a small part of Carmarthen _ Bay whence it passes near Kidwelly more northerly till about three _ miles south of Llandillo. From this part itinclines more southerly _ towards Abergavenny, but within five miles of that town it rounds "to the south through Pontypool and thence to the S. W. (rounding) through Liantrissent, but whence it arrives at the coast of Swansea Bay it spreads nearly in a line to Tenby, and thence t» the middle _ ofthe Western shore of St, Bride’s Bay. — 2 the B30 i MINERAL BASON. _ Mineral bagon the south side of this line they. rise southward, till they-come in SouthWales. to the surface, except at the east end, which is in the vicinity of Pontypool, where they rise eastward. 3. Lhe depths from the surfacc to the various strata of coal and ironoré depend upon their respe.tive local situations. . 4 The.deepest part of the bason is between Neath, in Gla- morganshire, and Llanelly, in Carmarthenshire ; the upper- most stratum of coal here does not extenda mile ina north and south direction, and not many miles in an east and west direction, and its utmost depth isnot above 50 or 60 fathoms. 5. The next stratum of coal, and those likewise beneath it, lie deeper and expand still longer and wider, and the lowest which are attended by parallel strata of iron ore, of which they are in some situations about 16 accompanied by irregular balls or Jumps of iron ore, occupy the whole. space between Llanmaddock Hill, near the the entrance of Burry river, to Llanbidie, from the Mumbles to Cribbath, from Newton Down to Penderryn, from Castle Coch to Castle Morlais, and from Risca to Llangattock, and in length of the - south side of the bason from Pontypool and through Risca, Tinkwood, Llantrissent, Margam, Swansea Bay, and Cline Wood, to Llanmaddock Hill,and on the north side through Blaenafon, Ebbw, Sirhowy, Merthyr, Aberdare, Aberpergwm, Glyntowy, Llandibie, and the Great Mountain, to Pembrey Hill, near Llanelly in Carmarthenshire, and their depths are at the center range of strata from 6 to soo fathoms. 6. The strata of coal andiron ore running from Pembry Hill, through Carmarthen Bay and Panbrokedire, to St. Bride’s Bay, are only a continuation of those in the counties of Glamorgan and Carmarthen, which lie next to and parallel with the north side of the bason, all. the remaining strata rising southward ; and the middle ranges on the north side of | the bason, are lost between where they meet the sea near Lianmaddock Hill and the south side of Pembrey Hill, in their course towards Pembrokeshire, i in consequence of a contrac- tion of the sides of the mineral bason, or rather by its becom- ing shallower ; for in Pembrokeshire none of ‘the strata of coal or iron ore lie above 80 or 100 fathoms deep, conse- quently all those which do not. lie. aboye 5 or 600 fathoms - in MINERAL BASON. Bee Bis Glathorganshire and Carmarthenshire have not reached Mineral bason this county, by reason of the bason not béing’ of sufficient in South Wales depth and width to hold them. 4. The strata of coal at the east end of the bason running from Pontypool to Blaenafon and Clydach and on the north side from thence to Nanty Glo, Ebbw, Beaufort, Sirhowy, - ‘Tredegar, Remney, Dowlais, Penderryn, Plymouth, Cyfarthfa, Abernant, Aberdare and Hurwain Furnaces and Iron Works, are of a cokeing quality, and from thence the whole strata of coal’ to St. Bride’s Bay alter in their quality, to what is called Stone Coal, (the large of which has hitherto been used for the purposes of drying malt and hops, and the small, which is called Culm, for burning of limestone) ; the several strata of coal from Pontypool: on the south side of the bason, through Risca, Llantrissent, Margam,and Cline Wood, to Burry River, Llanelly, and the south side of Pembrey Hill, are principally of a bituminous or binding quality. : 8. Notwithstanding the principal strata of coal in Glamor- ganshire? lie from 5 fathoms to 6 or 700 fathoms deep, still it has not been necessary to pursue these strata deeper than about 80 fathoms. ; . 9. The veins of coal and iron ore, in the vicinity of most — of the iron works in Monmouthshire and Glamorganshire are drained and worked by levels or horizontal drifts; which opportunity is given ‘by the deep valleys which generally run in a north and south direction, intersecting the range of coal and iron ore, which run in an east and west direction, under the high mountains, and thereby serving as main drains, so that the collier or miner here gets at the treasures of the earth, without going to the expence and labour of sinking _ deep pits, and erecting powerful fire-engines. However, in prodess of time, in situations where the coal-and iron ore | that are:above the level of these natural drains, become ex- hausted, it will -be found necessary to sink shallow pits, and - erect fire-engines for the draining and working of the coal _ and iron ‘ore, and at a future period, pits of greater depths, must be sunk for the same purposes. os There are-12- veins or strata of coal in this’ mineral depository, from 3 feet to 9 feet thick each, which ‘together make voi feet: and there are 11 more, from 18 inches to 3 3 feet, 384 MINERAL BASON Mineral Bason feet, which make'24% feet, making in all o¢ feet; besides a im SouthW ales: number of smaller veins from 12’ to 18. inches, and from 6 to 42 inches in thickness, not calculated upon.. 1x. By.taking the average length and breadth of the fore- going different strata. of coal, the amount is about 1000 square miles, containing 95 feet of coal in 23 distinct strata, which will produce in the common way of working 100,000 tons per acre, or 64,000,000 tons per square mile. 12. Ifthe whole extent of this mineral country was an ever plain, the border or outbreak of each stratum would appear re- gular and true ; but owing to the interposition of hills, valleys, the edges of the strata,if nicely measured and planned, would seem indented and uneven, yet in many instances the due range is totally thrown out of course, in eacesansane of knots, dikes, or faults.. 13. These faults or irregularities. are sail tidied to. the edges of the strata, but they take grand ranges, through the ‘interior of the bason. generaly in a north and south direction, and often throw the whole of the strata, for hundreds of acres together, 40, 6o, 80, or 100 fathoms, up or down, and still there is seldom any superficial appearance, that indicates a disjunction, for the wg faults frequently lie under even sur- faces. 14. Asievery stratum rises regularly from its’base tothe sur- face, and frequently visible and bare, in precipices and’ deep dingles; and often discovered where the earth or soil is shallow in trenching, or in forming high roads, and by reason of the whole of the country within this boundary being so perforated by pits, and so intersected by the various operations of art and nature; it'is not probable that any vein of coal, ironvoré, or other:sttatum remains undiscovered in this: mineral bason. 15, Glamorganshire engrosses far. the greatest portion, of coal and iron ore, Monmouthshire the next in point of quan- tity, Carmarthenshire:the next, Pembrokeshire’ the next, and Brecknockshire possesses the least. 16, The strata of coal andiron ore in the last named county; - which are the lowes: in the:bason, break out northward; and only take place ‘in the three following distinct spots, viz. 1st. From TurchRiver (which is the boundary between Lord Caw= por and Cuaxves Morcan Esq. ) across the river Tawe and the - GLACIERS OF CHAMOUNY. 385 the Drin Mountain to the great forest of Brecon, 2d; A cofner Mineral bason of ground from Blaen Romney to the north of Brynoer. 3d. i" SouthWales. Another spot, from Rhyd Ebbw and Beaufort Iron Works, through Llwyn y Pwll, near Tavern Maed Sur, to where it | joins Lord Abergavenny’s mineral property. 17. Note. A'principal fault is observable at Cribbath where the beds or strata of the limestone stand erect : another, of comsiderable magnitude, lies between Ystradvellte, and Pendertyn, where all the strata on the north side of the bason are moved many hundred yards southward (as at Dinas. ) 18. Note. The limestone appears to the surface all along the boundary line in the counties of Monmouth, Glamorgan, Car- miarthen, Brecon, and no doubt can be entertained of its due range from Newton across Swansey Bay to the Mumbles, and from Llanmaddock Hill across Carmarthen Bay toTenby. In Pembrokeshire it appears to the surface on the south side of the bason,at Tenby, Ivy Tower, Cockelard, Bit, Church- Williamston, Lawrinny, Cord, Canta, and Johnston, and on > the north side of the bason, at Templeton, Picton, Harriston and Persfield ; yet it certainly forms an underground con- nection from point to point. IX. On the Water Pits of the Glaciers of Chamouny. By a Cor- respondent. : To Mr. NICHOLSON, SIR, Cork, 13th April, 1807. I JUST now was looking over a paper from Count Rumford, Observations -in your Journal, on a curious phenomenon on the “ Glaciers of sed eis -“ Chamouny,” with respect to.a pit which he observes was Gone Rum- formed in the ice. The manner in which he accounts forit, is, ford, I think, inconsistent with his own rules. The manner in which I would account for this phenomenon, is, that as cold water Vou. XVI.—May, 1807. Gg lying 386 Distance of ‘DISTANCE OF THE STARS. lying on ice melts it sooner than warm water, so for the same reason the water which lay on the top of these pits was, as he i observes, warmed by the wind which passed over them, and that which was in the bottom of the pit cold, of course it had a tendency to melt downwards rather than at the sides. Now, Sir, if you will have the goodness to publish this in your Jour- nal, so that Count Rumford may see it, you will oblige me in hopes that I may see what he thinks of my account of this phenomenon. | Jam, ‘Sir, &c. &c. A constant Reader. , aaa Remark by M. De Lavan neon the Distance of the Stars. | Donrine the last century it has been believed, that the annual parallax of the stars, that is the difference of their situ- ations in the course of six months, relative to the position of the earth, does not vary a single second; whence it results that their distance must exceed seven millions of millions of leagues. _M. Piazzi, at Palermo, and M. Callandrelli, at Rome, have ' recently made observations on several of the stars, from which it appears that some of the stars give a difference of five seconds, particularly Lyra, which, next to Sirtus, is the most brilliant star in our hemisphere, from whence it results that it is-one of the least distant. If there be five seconds of simple parallax, the distance ought to be fourteen hundred thousand millions of leagues, that is to say, five times less than. was - previously supposed. But these observations are not yet'suffi- ciently numerous and complete; to afford a eet certain conclusion. XI. WATER OF THE 3EA. 387 XT. Observations on the Soda, Magnesia, and Lime, contained in ' the Water of the Ocean ; shewing that they operate advan- " tageously there by neutralizing Acids, and among others the Septic Acid, und that Sea-Water may be rendered fit for’ washing Clothes without the Aid Peta 8 at SamuEL L, (pose hag os New York.* . . © Many attempts have been made to render the water of the!Observations sks A i ca pga 0 and facts re- ocean fit for the purposes of drinking and cooking, and some of: Epecting pei these have been attended with. flattering prospects: of ‘utility. component Ry a cheap and easy process, water telerably fresh may-be : ae distilled from common; salt water, go as to help materially inand the useful a case of scarcity or want; on board.a ship of good equipment. te epee " The names of Hales, Lind and Invine, are remembered to their: honour; for their exertions in this work. =... . To furnish needy men with the means of eating and ain kihipy is certainly a noble discovery. But there is another operation scareely: less necessary. to the preservation of health than eating and drinking, and that is washing as applied to the human body, and more particularly to the clothing which it» befoulsz In a communication to: professor Duncan, which has’ been published in the Edinburgh Annals of Medicine for 1799, and in the third volume of the New York Medical: Repository, I have endeavoured to state the facts in detail concerning the. matters secreted from the skin and wiped off by the clothes and to shew how some of these became unwholesome,. or in- fectious: and: pestilential, as they grew nasty. It was there: stated that soaps and alkalies would render foul clothing clean,: and both prevent and destroy animal poison if it was engender ing there. And in a letter I wrote to Timothy Pickering, late Secretary of State to the American Government, in November: * American Transactions, vol. v. The Doctor wses*the term septic for azotic er nitric. if ate 1799, 388 Observations and facts re= specting the component parts contained in’ sea water, and the useful applications of that fluid. WATER OF THE SEA. 1799, I recommended barilla or soda as a substance by which the salt-water of the ocean could be so softened and altered in its qualities as to become fit for washing the clothes of seamen, A sea-vessel is peculiarly fitted for concentering foul and corrupting things, and for converting them into pestilence and poison. This is one of the most common accidents in sailing to the latitudes where there is heat enough to promote corrup= tion and toexalt,septic substances into vapour. One of the most disgusting sights during a voyage is the personal nastiness of many of the crew. It is pretended that much of this is necessarily connected with the service, that the work is dirty, and especially that fresh water cannot be spared from the vessel's stores to wagh the company’s clothing; that soap cannot be used with ocean-water, that salt-water alone will not get them clean, and that therefore they are under a necessity of being uncomfortably nasty on long voyages, especially toward the latter part of them. Now, nastiness of a man’s person and garments is necessarily connected with a similar condition of his bed, bedding, hammock and berth, and most commonly of every thing he handles or has ought to do with. Ifa seaman has strength of constitution to keep about and do duty, his feelings are nevertheless very uncomfortable, he is thereby predisposed to disease and in danger every moment of becoming sick; and if this should really happen, his chance of recoveryis exceedingly lessened by the filth with which every thing that touches him is impregnated, and_ the. venom into which that filth is incessantly changing. Thus, the great difficulties with which a seaman has to struggle, are Ist, the unfitness of ocean-water to wash with; and 2d, the inutility of soap to aid that fluid in cleansing his clothes. If these can be surmounted,’ he will have no excuse for his uncleanness. If after this he becomes uncom- fortable or sickly from that cause, it will be — to his own laziness or negligence, - » Few subjects have been discussed with more solicitude than the one, How did the ocean acquire its saltness? Whether that mass of waters derived its briny quality gradually by dissalving strata of salt, or. whether it was furnished by its Crea- . tor with a due quantity of that material from the beginning, are, WATER OF THE SEA. 389 are questions not necessary now to be answered. Itis suffi- Observations cient to observe thatit is kept sweet and guarded against offen- pa iit siveness and corruption by the great quantity of alkaline component matter it contains. The ocean may indeed be considered as Laeger aig: containing some portion ofevery thing which water is capa- and the useful ble of containing or dissolving, and its water is therefore found pep aes a to furnish different results on analysis, when taken up from different depths and in different latitudes, Yet various as the composition of occan-water is, it always contains soda, magnesia and lime, in quantity considerable enough to be easily detected. Of these soda is the most abundant. Magnesia is next in quantity. And lime, though plentiful, is believed to exist in smaller proportion than either, The alkalme matter so plentifully dispersed through the. water of the ocean, exerts its customary neutralizing power after the same manner and according to the same laws which govern jts several kinds on the land and in other places. The acids commonly, present in ocean-water are the suf- phuric, the septic and the muriatic, The former of these ~ exists apparently in small quantity, and is only mentioned because in some experimenis it has been said to have been obtained from it in the form of a sulphate of lime, though ac- cording to the law of attractions, we might expect to find in it sulphate of soda. The vast amount of animal mattcr existing in the sea, would lead one & priori to a persuasion that in certain cases, particularly along marshes and shores -were the stagnating water was much heated, putrefaction would engender septic acid, and this would insome measure mingle with the water in its vicmity, and not fly away wholly in vapour. The quantity of this acid is so considerable in some coves and bays where salt works have been established, that a quantity of it adheres to the muriate of soda or-com- mon salt and vitiates its quality. And this happens jn some situations to so high .a degree, that Neumman (Chemical Works by Lewis, p. 392,) takes notice of it, observing * that sea water often contains a zitrous matter, the acid spirit dis- tilled from sea salt proving a menstruum for gold, which the marine acid by itself never does, and which ‘nothing: but pres the 390 WATER OF THE SEA. Observations the nitrous will enable it todo. Though however this is fre- and facts re- pb : : speching te quently the case, itis not always: Ihave examined marine component __ salt whose acid had noaction upon gold.”—As to the mu- parts contained atic acid, whether it is as some of the older chemists sup. i sea Water, and the useful pose a modification of the sulphuric and the nitrous, or as applications of that fluid. certain of the moderns. believe, but a compound basis of “sulphuric and hydrogene, there is evidence enough of its ex- istence in the ocean in very. great, plenty.—On the whole, it may be concluded that sea-water always contains muriatic acid, frequently septic and sometimes sulphuric. ; There are thus three predominating a/kalics and as many acids in the ocean; and by the intervention of water they are liquefied and put in a condition to act each upon the. other. Consequently the soda in the first place, as the stron- ger alkali attaches and neutralizes the acids in the order of chemical affinity, and forms sulphate, septate and muriate of soda. But as the fwo former are comparatively rare or scarce, the latter is the predominating compound. When there is any acid in the water beyond the capacity of the soda existing there to neutralize, that part is attracted by the two earths, and acording to the force of their respective combinations, forms sulphates, septates and muriates of lime and magnesia. These salts with earthy bases, in which the muriatic acid is by far more abundant than the other two acids, constitute the bittern and scratch or slaek of the salt makers. These salited earths attract. water so strongly that it is difficult or impossible to make them crystallize; but wherever they are they keep up a dampness and refuse to. dry. When chemists speak of sca salt, they wish to be under. stood .as meaning “ the pure muriate of soda.” This neu- tral compound however in its pure state is a great rarity. Perhaps indeed there is no such thing. Experience shews it is always mingled with greater or less quantities of the de/i- quescent salts with earthy bases, And these are so abun- dant in some. sorts of salt that they render it unfit for the pre- servation of animal provisions. Beef and even pork, are not guarded by salt so adulterated, from becoming tainted and putrid. That sea salt of this impure quality should be fit for ; curing —— WATER OF THE SEA. 39) ‘curing provisions, it ought to undergo a particular refining patios operation to rid it of its foreign admixtures. For want of specting the sucha process, some sorts of sea salt, though fair. to the eye, Component _ Piao: tie , i parts contained do not possess an intire and undivided antiseptic power, but so in sea water, far as the muriate of soda in the mass is alloyed by the mid- pats bai | . dle salts of magnesian and calcarious composition, those that quid. parcels of common salt so vitiated become unfit for opposing completely the process of putrefaction. And so far they make a departure from the antiseptic power of pure muriate of soda, the manner of whose action, I endéavoured to in- vestigate ina Memoir addressed to professor Woodhouse and published in the seoond volume of the New York Medical Repository. By reason of these foreign and adventitious matters, it happened in Sir John Pringle’s- experiments, that the com- mon ‘salt employed by him, instead of preventing the cor ruption of meat, when added in small quantity rather promo- ted its decay. (Paper III. Exp. 24.) His trials he ob- serves were made with the white or bozled salt kept there (in London I suppose he means) for domestic uses. (Appendix to Observations on Diseases of the Army, &c. p. 345, Note.). This kind of salt is known to abound with the earthy salts with which ocean water is charged. Dr. Perciyal’s experiments on sea salt have a tendency to shew that the septic quality ascribed by the learned Baronet to small quantites of common salt is owing to the mixture of bitter sait with it. 'A quantity of this, he observes, adheres to all the common salt used for culinary and dietetic purposes, and as far as its influence goes, it counteracts the wholesome and preservative powers of the clean and unmixed muriate of soda (1 Essays Medical, &c. p. 344,) and that this septic quality of the sea salt depended upon the presence of some’ heterogeneous substance was the opinion of Pringle himself. (Ibid. p. 347.) . Such then being the composition of ocean water, it is easy to explain wherefore it is not fit by atself, for washing gar- ments and making them clean. «It has a deficiency of alka- ‘line salt init; and alkaline salts are well known to be*the most excellent and complete detergents, And it is quite ag easy 392 WATER OF THE SEA. Observations easy to assign a reason why it will not answer to employ soap and factsre- |. ee de ea pth: blige Aap sae in : : evening kbe with ocean water. The acids united to the lime and magnesia coinponent —_ being more strongly attracted by the alkali of the soap, quit vartscontained ,,_-_ si * 5 ie r Soa WE. theit connection with those earths, which fall to the bottom, and the useful while the lighter and deserted oil rises to the top. The ac- ib a a tivity of the alkali of the soap thus overcome by the neutra- lizing acid of the water, can be of little service, and the disen-, gaged grease immediately thereafter becomesa real im- pediment. The basis of all hard soap 1s ne The alkaline matter of soft soap is potash, This probably happens because the former is prone to effloresce, the latter to deliquesce in the air. The reason of mingling oil, turpentine and tallow with potash-is that this salt is too corrosive to be handled naked or alone. By its causticity potash destroys the skin and flesh of the washer, and unless carefully employed, will destroy the goods too. But this is not the case with soda; which in conjunc- tion with carbonic acid may be dissolved in water without ex- ercising any caustic effect upon the arms and fingers of the person who uses it. By virtue of this convenient and excellens ‘ quality, the carbonate of soda can not only be used ina lixi- vial form to cleanse goods, but may be employed to alkalize or _ soften ocean water and to render it fit for washing withs It has been ascertained long ago by Professor Home in his experiments on bleaching, that neither sea salt nor any other of the perfectly neutral salts composed of an acid and an alkalt give any hardness to water; that the common sorts of sea salt make water hard by means only of the heterogeneous salts they retain from the bittern; and that alkalies by precipitating the earth of salts with an earthy basis and by neutralizing their acids, will soften water. Ocean water, it has been shewn, euides a perfect neutral salt, contains a quantity of saline matter with earthy bases. To these latter, it owes its hardness, or quality to decompound soap. Carbonate of soda decomposes these terrene salts and forms with their acids respectively perfect neutral salts. . The water thereupon becomes soft, or in other words, fit for wash- ing goods, (To be continued.) Wer Soe 205 D Wi ou. fe a WUMead te pene : po } ee Ota S Be Z 7] 4y Yy YY “) yl \ x \\' gi O \\\ ‘s. Mop : no eS ) WW”, ¥ ey was aM, saa " * ; J ¥ IN ars Ce ATG . Necholoons flhilos fowrnat, VoL XVI. pe 3p. 60. é wy fs OT waapie feneamatic Afparatis il mill me ine mi ii "ee ne i a ; an TTT Z Mt uit ——4 = ~ Ht i I 1) Ht f rs Why I I || ey |) i = T 1 i if i Il | H} | IHF i i i Hil | \ I i i i 1) il I HMMA Mh Ye. Th ) | | ATT PAN a TTT Yj) = TTT TS i L Bean gee: auf cab come ar yah snc enya eo 2 dle th alane aa pan fe sos x INDE X. A. A, on the best methods of destroying the insects which infest dwellings and furniture, 324 : Abildgaard, M. on a species of menac, 139 Abroma augusta, an.useful vegetable in India for the manufacture of cordage, 250 Acoustics, experiment: in, called the Invisible Girl, exhibited in London, 69, 119 Agaphi, Demetrius, on turquoises, 183 Agave tuberosa, of India, 252 Air, currents of, 173 Alburnous vessels of trees, inverted ac- tion of, 60 Alderson, Dr. om the methods of improv- ing poor soils; where manure cannot be had, 360 | Alexander, Dr. on the effects of opium on the living system, 246 Alum mine near Glasgow, 233 Anatase of Hauy,. probably a variety:of rutile, 129 Anderson, Dr. his. “Agricultural Re- creations,” 152 Angles; small, three modes: of mea- suring; 23. * Antis, Mr. his.improved door latch de- _ seribed, 155 Apricots, improvement: in the. culture of, 144. Argil, electrical experiments with, 103 “Art: of: Universal, Correspondence,” ’ published in 1802, notice of, 204 Asham, Roger, his curious observations - on the: wind, 171 Astrometer, for determining the appa- rent situation of thestars, &¢, 320 Vou, XVI. Astronomical circle, description of an, 200 Astronomical intelligence, 239 Atmosphere, state of water in the, 4 -—Proportion of its constituent: parti- cles, 75 Ausein, Rev. G. his apparatus for trans- ferring gases over water: ormercury, 377 B. Bakerian lecture on electricity, read be» fore the Royal Society, 79: Balance for a time-keeper, Mr. Hardy's, 120 | Band-wheel to regulate the velocity of machinery, 126 Banks, Sir Joseph, 73—Letter to, on the marine barometer, 107, 173——= Ditto, ona discovery of, native. mini+ um, 127—His account of the stratum incumbent on the columns at Staffa, 290 Bardsley, Dr. 160° Barometer, marine, observations on du- ting the examination of thecoasts: of New:Holland, &c. 107, 173 Barytes, electrical experiments on, 101 Basalt, origin of, 277 Bason, mineral, in the counties of Mon- mouth, Glamorgan, Brecon, Caer- marthen, and Pembroke, 381 Beavers in Westphalia, 239 Benzelius.on the use- of lichen among the Laplanders, 211 Berthollet, on the power of chalk to de- compose salt, 371. Biberg’s Economy of: Nature, 567, . 372 Black, Dr. 233 Blacking:for leather, 237 b Bolé INDEX. Bolt for bookecase doors, 154 Bond, Mr. 302 Bostock, Dr. J. his experiments on palm oil, 161—(See also p. 320, for errata. ) Brewster, Mr. his new astrometer for finding the rising and setting of the stars and planets, and their position in the heavens, 326 Brinkley, Rev. J. communication from, 23 ' Brown's theory of irritability, 347, 548 Bruckman’s History of Turquoises, 183 Buch, Von, his discovery of rutile, 182 Bugs, inquiry relative to the means of destroying, 324 Burrows, Mr. 302 Butterby mineral waters, 319 C. C. Letter of inquiry from, respecting shoe blacking, 237 Calculi, gouty and gravelly, experi- mental inquiry into, 335 Callandrelli, M. his observations on the stars’ distance, 386 Caloric, observations on Professor Les- lie’s theory of, 270 Calorimeter, description and use of, 167 Campbell, Dr. on the Dutch ere fishery, 149 Canton’s phosphorus, 102 Canton, Mr. John, his observations on the diurnal variation of the horizontal magnetic needle, 297 Carraderi, Dr. observations of, shewing that water is not deprived of its oxi- ‘gen by boiling, 75——Reference to his paper on the Jight of natural phos- * phori, 103 Catch-water drains, 369 Cavendish, H. Esq. 73=