~ > tere . hatte a Dinivbuiatateretnes ‘phatase bale Phe 1 , by meee hog wee ete vg ie rs " Ae ek noe ta a 41 5) eee eta ntti tates Maptatator serestntes Ha i at ise Relaealiyee al en let cad eet an btn re ty i Ih fens ; peicteba i Sythe . ret at rhe wahoo belay iste! a in ; f d it if M Be fehelarectiore tern el rintehe fiatetatenae eeratarere bAererars ti prattehotebes Bre i by a if ey 4 b gies) in str held Apaettehicdthbndn te esses xe ee epetseassess pea Ese i TERY ota bat alls i} 7 mae teed ieee eetatesernin * sta ees : ee ve bs See abhi ibtebetyinty nein fodeshieitis ; gopaty rela bebak sie eTatat a LO nt 1 bas Hae bbls on basses arabada ibortetsole wninn lit te jareganei vices ra Matern 554 DEI ORIORMONONOMONIOROATORAORIORI ORIN, bv} (a) 7 Ravtre Idler. é Philos. Trans. Vol XID. Tabi pz. NS SheMale a . 7 poo lhe’ Uenmoula of Malacea. Jdife. 7 ee ‘What genus this bird is properly to be referred to, I fhall not pretend todetermine; but if you think this, though but imperfect account, worth the com- municating to your Society, you have my leave; and Tam, with refpec, oda Your moft obedient, | and moft humble fervant, London, Oober 13, 1771. De ane! 13, 177! James Badenach, M, D, [4] el se of the L fpecifis Chatbasters which diftinguifh the Rabbit from the flare: In a Letter to Samuel Wegg, Efg; T. and Vice-Prefident of the R. 8. from the Honourable Daines Barrington, VP ORGA, November 24, 1771 DEAR SIR, Read Jan. 16. CALLED lately at your Hate to ee? meafure fome parts of the quadruped which you have received by the laft ihip from Hud- fon’s Bay, and am now convinced that it fhould be rather confidered as a Hare than as a Rabbit, which latter name it hath obtained in that part of the world, You will find meet from what Tam going to ftate, that it is not very eafy to fettle a fpecific, and at the fame time {cientific difference, between thefe two animals, even when the greateft authorities in Natural Hiftory are confulted.. | Ray [a] makes the diftin@tion between the Hare and the Rabbit to confit in the fmaller fize of the Jatter,. its property of burrowing, and the greater whitenefs of the flefh when drefled: he chiefly relies, however, on the one being larger than the other; {@] Syn, Quadr, Art, Lepus. F as Poy as this is the moft material circumftance in which they are fuppofed by him to vary, whether exterior or interior. Though bulk is undoubtedly a very proper cire cumftance to be attended to in the defcription of an animal; yet recourfe fhould never be had to it’ in eftablithing a {pecific difference, except it is the only criterion which can be fixed upon, and the dif- proportion in point of fize is very great, An Hare, however, does not exceed a Rabbit fo much in bulk asa Patagonian does a Laplander, or a maftiff does a lap-dog, which yet are not to be confidered as differing in fpecies. 2 Befides this, age, climate, and food, as well as other circumftances, often occafion great diftin@ion between animals of the fame fpecies, in point of bulk. ‘The Hare (for example) which ts found in moft parts of North America, 1s a third lefs than the European Hare, and confequently is fcarcely larger © than our Rabbit [4]. | | The next criterion which Ray fixes upon to di- ftinguith the Rabbit from the Hare, is that the latter burrows in the ground; this; however, only holds with regard to the warren Rabbit, for thofe which are called hedge Rabbits feldom burrow, and many -of them fit in forms as Hares do. aa [4] Monf. de Buffon is mifinformed, when he afferts, on the contrary, that the American Hare is larger than that of Europe, (Hitt. N.t. VI. p. 246) if I can depend upon the accounts I have received from thofe who have long refided in America, as well as fome fluited {pecimens which I have examined. See alfo Mr, Pennant’s Syn, of Quadr. p. 249. | The 6 The third and laft is, that the fleth of the Rab- bit is more white when dreffed; which diftinGion is always to be found between the European Hare > and Rabbit, but it does not often happen that one can drefs the flefh of an animal which comes from another part of the globe; it is therefore a erite- rion we can feldom have recourfe to. — Linnaeus, thus defcribes the Rabbit in his Fauna Suecica, (Art. Lepus). Lepus Caniculus,cauda abbreviata, Aur iculis Nudatis. : Lepus caude brevifima, pupils rubris, With regard to the firft circumftance of the Cauda abbreviata, he.equally applies it to the Hare in his Syftema Nature, publifhed in 1766, and drops the Cauda breviffima of the Fauna Suecica; where in propriety the Rabbit fhould not have found a place, as it is not indigenous in Sweden, the climate be- ing too cold aay ) Linnezus therefore could only have defcribed from a tame Rabbit, which I fuppofe had balder Ears by fome accident than common, as his next criterion is Auriculis Nudatis, 1 have examined lately a great number of Rab- bits, and do not find that their ears are balder than thofe of a Hare: this fecond circumftance therefore eftablithes no {pecific difference, From the third and laft particular which this great Naturalift relies upon, I am alfo convinced that the {pecimen before him was not only a tame Rabbit, but that iS fur was either white or carroty, becaufe Rabbits of thefe colours only have red pupils [c]. {c] [have examincd a great number of Rabbits thus coloured, which commonly have red pupils, though I have ae fome I find al i find accordingly, that Linnzus hath omitted the pupillis rubris, as applied to the Rabbit, in the twelfth edition of his Syftema Nature; but adds another diftinction, which will be found equally to fail. ; ae 3 : - He there fays, that the ears of a Rabbit aré fhorter than the head; whereas thofe of a Hare are longer: which is a juft obfervation, when the war- ren Rabbit is examined; but the tame Rabbit (and particularly thofe which are white or carroty) have ears that are confiderably longer than their head. - This circumftance, therefore, eftablifhes no mote a fpecific difference between the Rabbit and the Hare, than the greater length of the ears of a dog would, which in fome varieties of that animal are known to be exceflively long. : Pb ebHlalaahiye Monf. de Buffon, in his defcription of the Hare and Rabbit, agrees with Ray that there is nothing either exterior or interior which feems to conftitute a fpecific difference, though he endeavours to efta- blifh an inconteftable proof that they are really dif- tinct. | | , He informs us, that he had tried to procure a breed between Rabbits and Hares, but never could fucceed in the experiment. This moft ingenious and able writer does not fate, however, at what ages the Hares or Rabbits were thus confined, which is known to be a moft material with black: the grey Rabbit however néver hath eyes of a red colour. When the white Rabbits are very young, their eyes are often like a ferret’s; but when they are grown to their full fize, the pupils are generally quite red. Bi PEN : circumftance, WY PO shh oe iS 3 ¢ 8 ) a ihiientl aie by thofe who have raifed male Caitary birds [1]. Monf. de Buffon’s expreffion is, < J’ai fait eever «* des hafes avec des lapins,” which at firft feems to imply that he had reared them ee their earlieft infancy. Upon confulting however the didignars of T're- voux, the compilers inform us the word Ekver[e] often fignifies the feeding and keeping an animal, without refpect to its age; and they cite its being ap- plied to elephants in Europe, which it is believed never bred in that quarter of the globe. But the beft expoiitor of the fenfe in which an au- thor ufes a word is in other parts of the fame work. In the fifth Vol. of his Natural Hiftory, p. 210. Monf. de Buffon gives an account of his making the fame fort of experiment between the Wolf and a Dog, in the following words : «¢ J'ai fait ever une louve prife ae les are «© de deux ou trois mois, In this pafflage, the word is applied to a wolf, of three months old, and to fhew that Monf. de Bufs - fon did not think the age at which the animal is confined.to be material in fuch an experiment, he immediately afterwards ftates, that he caught fome [a] Birds which differ fpecifical ly fearcely ever breed ex- cept both are taken early from the neft, and particulerly the, hen ; I have procured a breed- from two Tobie in a cage the prefent year by attending to this circumftance, and I believe I - could equally fucceed with almoit any other kind of birds, as when they are thus reared, they have not the leaft awe of man. fe] “© Elever fignifie, Nourrir auffi, foit plante, foit animal, es & en avoir fain.” «© Ona de la peine a élever des elephans en Europe.” . foxes — Lo] -foxes in {nares (which were probably therefore full grown), and kept them a confiderable time with dogs of different fexes. After this, he fays [¢], it is eailent from thefe ex- ‘periments, that wolves, foxes, and dogs are {peci- fically different, without diftinguithing “between the foxes being full grown when caught, and the wolf which was only three months oid. But the decifive argument againft Monf. de Buf- fon’s experiment not being fatisfatory, is to be found in Mr. Pennant’s Synopfis of quadrupeds, p. 144: where he informs us, that a breed was actually pro- ‘eured between a dog and a wolf at Mr. Brooks's (animal merchant) in Holborn. Monf..de Buffon alfo fuppofes that the Rabbit is much more fagacious than the Hare, becaufe, both having equal powers of burrowing, the one thus fecures himfelf from moft enemies, whilft the other, by not taking the fame precaution, continues liable to their attacks. There are, however, feveral cau es for the Rab- - bit’s burrowing, and the Hare’s neglecting todo fo. In the firft place, the fore-legs of a Rabbit are fhorter in proportion to its hind legs, and at the fame time much ftronger; the claws are alfo longer and fharper, refembling much thofe of a mole. — I have before obferved that the Rabbits, which the {portfmen call Hedge Rabbits, feldom burrow ; and they neglect taking thistrouble, for the fame reafon that induces the Hare to truft to her form, be- fe] Hift. Nat. T. v. p. 213. Vou. LXI. Cc gaule f ro J eaufe they have an opportunity of feleQing @ pro-- per place for their concealment. The ground, however, in a warren, is eaten fo very. bare by. Rabbits, that it is impoffible for them to hide themfelves if they make a form in any part of it, and they therefore very. judicioufly-choofe to bur- row under ground. Another reafon, perhaps, for the Rabbit's burrow- ing arifes from the animal’s being not only born,. but continuing the firft fix weeks of its-life, under _ ground; they therefore only pra@tife what they have feen and learned in their earlieft infancy, as birds- from: the fame circumftance always build their neft: in the fame form, and with the fame materials. I therefore cannot allow entirely of the diftinc-- tion arifing from the fuperior fagacity of the Rab-- bit, becaufe it burrows; and Monf. de Buffon him- felf informs us, that tame Rabbits turned into a warren do not burrow for many generations [f}. - Having thus endeavoured to fhew that no proper criteria have hitherto been fixed upon to diftinguifh: the Rabbit from the Hare, I fhall now venture to: fuggeft the two following, which, I fatter myfelf,. at be found lefs liable to the rae exceptions. If the hind legs of an European Hare are mea-- fured from the uppermoft joint to the toe,. the num-. ber of inches wiil turn out to be juft half ef the: length of the back, from the rump to the mouth: (the tail not being included). The hind legs of the Rabbit being meafured in: the fame manner, and compared with the back. are not much more than one third; from which: [f] Hitt. Naw T. 5, p..306.. : is: [iat] at feems not unfair to confider any animal of the ‘Hare genus, (whofe legs thus meafured are lets ‘than the half of the diftance from the ramp to the ~mouth) as a Rabbit, and on the contrary when they are either one half, or more, as a Hare. If the fore and hind legs of a Rabbit and Hare -are alfo refpectively compared, it will be found that “the fore legs of the former are proportionally more ‘fhort, than-thofe of a-Hare. By both thefe criteria the quadruped from Hud- fons Bay muft rather be confidered as a Hare, than a Rabbit (as it is called in that part of the world), according to the admeafurements fubjoined, which -include the refpective proportions alfo of the Alpine. ‘Hare [4]. ForeLeg. HindLicg, Back and Head. inches. Inches. ‘Inches. Rabbit e 62 164 Hare IL 22 -Hudfen’sBay |. - : : g ~ Quadruped ne : . ee 10¢ 22% “Alpine Hare From the From the | uppermoft uppermoft 4 joint tothe joint tothe toe. toe. From the proportion of thefe parts, in the Hud= fon’s Bay quadruped, according to this table, I flatter myfelf, that it may with greater propriety be claffed as belonging to the Hare {pecies, than by any other marks of a fpecific difference which have been hi- therto relied upon. [4] This fpecies of Hare is found in the Highlands of Scot- land, whence I received a fpecimen, which I had the honour of prefenting to the Mufeum of the Royal Society. Sie I de [ve2:| : T-do not mean, however, to aflért from this, that- a Hare and Rabbit are certainly of a diftinét {pecies:; as this can. only be fettled by failing to: procure a ‘mixed breed between the animals after repeated ex-_ periments, and under proper cireumftances.. I fhall now add, that the Hudfon’s Bay animal alfo : approaches nearer to the Hare than the Rabbit, by the fore legs being much. more flender in. proportion to the hind legs than thofe of a Rabbit are; and that. the claws are alfo fhorter. As-the animal likewife- happened to die on the 22d of this month, I boiled the flefh; by your permiffion,. which was as brown- as.that of the European Hare ; and confequently it is. to be clafled as of that {pecies, according to Ray?s . third criterion. But the moit curious particular in this quadruped: is the white wintercoat, which:covered, at its death, the greateft part of the animal. This. refutes at once the notion, that animals in- the more Northern countries become white by the intenfe cold of the climate, becaufe this quadruped. arrived’ in England about the time that the change: fhould have begui. if it had continued in Hudfon’s. Buy. As the animal was born, however, in a country- - where: {now. covers the ground during the whole: winter, it is providential that the formation of its parts and juices fhould be fuch as-{hould periodically occafion fuch.a change in the fur; and perhaps, it is the only quadruped. which ever was brought froma climate of fuch rigour, to a more. temperate one, before the alteration of the colour in its hair. took. lace. ) { By ats By four different fpecimens in that valuable col- YeGtion of animals, which the direétors of the Hud- fon’s Bay Company have lately procured from a™ country unvilited but by their own fervants, it ap- pears that the change begins in Odtober (or perhaps the latter end of September) and that it is compieat- ed in January. We owe this knowledge of the regular grada- tions of colour in this animal at different intervals’ as the winter advances, to the very fenfible attention ‘in the company’s fervants, who have ticd memoran- dums to the fpecimen of each animal, which in- form us of the day and month in which it was caught. lf the fur of your quadruped: is accurately exa-- mined, it will be found to confift of two diftin&. coats of hair, one of which is much more thinly. {cattered over the body, but is more than twice the. length of the inmoft covering, at the fame time that it is vaftly ftronger. This upper and thinner coat is compofed alfo of hairs which are white from the top to the root,. and. form the winter furtout for the animal :. its brown fur, therefore, never becomes: white, but is concealed by the upper coat. This additional covering feems to be abfolutely necefiary. for the animal’s prefervation, as it is there- by enabled to endure the rigour of a Hudfon’s Bay winter, whilft at the fame time the colour of the ‘new fur being white, prevents its being diftinguifhed by its very numerous enemies [ g].- If this furtout, however, was not to fall off during the f{ummer, it would prove the deftruci.on of the. animai « 2: | [ 4 ] animal: becaufe the extraordinary heat from fucha warm cloathing would not only become highly in- convenient, but the colour alfo (being white) would point the animal out to its purfuers; as Mr. Graham takes notice in his very accurate. catalogue, that this ea does not burrow. This very fenfible officer of the Hudfon’s Bay Company likewife adds, that this animal continues always near the fame {pot; that its coat is brown in fummer; that they breed from 5 to 7 young ones, and fometimes twicea year: he alfo ftates, that the RE ata medium is nearly 416. Iam, Dear Str, Your mott faithful, -Ahumble fervant, Daines Barringten, {g] It thuft be admitted, ‘however, that the white coat digas the winter is nota farjeicut protection tothe animal againft the fagacity of the arch-enemy man. Mr. Reinhold Forfter (who is a native of Polifa Pruffia) in- forms me that Hares are found in the northern parts of Europes, when the fnow is on the ground, by an exhalation of vapours ‘from their bodies, whilft they are fitting in their form, efpecially if the fun happens to fhine. I can very eafily conceive that fuch a vapour may be diftin- guifhed, as I have frequently in a frofty morning feen the air -condenfed, which hathiifued from the mouth of fo fmall a bird asa Rota. when in full fong. Ili. Az oe tors } Il. Ax Account of the fulphureous srineral Waters of Caftle-Loed and Fairburn, iz the County of Rofls; and of the Salt _ purging Water of Pitkeathly, in the County of Perth, 7 Scotland: By Donald Monro, M. D. Phyfcian to the Army, and to St. George's Hofpital, Fellow of the Royal College of Phyficians, and of the Royal — Society. Read Jan. 235 . § no account of thefe waters: has: ee ff hitherto been publifhed, I thought: that the following would be agreeable to this So-- ciety. . Of the fulphureous mineral water of Caftle-Loed,. Having heard many gentlemen from the county: of Rofs {peak of thefe mineral waters, I wrote to Sir: John Gordon, of Invergordon, and begged the fa- vour of him to afk fome phyfical perfon in his neigh- bourhood to fend me an account of them, and lke- wife fome of the waters in bottles ; and foon after he was fo obliging as to fend me fix bottles of the Caftle- Loed, and fix of. the Fairburn waters, fealed and: corked, [ 16 } corked, and along with them a letter from Dr Alexander Mackenzy, dated Auguft 9, ue con- iste the following account. | «¢ ‘The Caftle-Loed is a {trong fulphureous mine- — «* ral water; when taken up from the fpring, it is «© as pure and tranfparent as the clearef{t rock water ; « but if kept in an open veffely or an ill-corked ‘© bottle, it toon becomes of a miiky fort of foulneds, ~s¢ and it lofes its {trong fulphureous {mell in twenty- «¢ four hours. «The bottom of the well, and of the channel <¢ which-conveys its water from thence, is black, as sif dyed with ink; and the leaves -of the ailer <¢ bufhes that fall into the well, or into its channel, “© foon contract a blackifh colour in the water; but ‘¢ when taken out, and dried in the fun or fhade,. «* appear covered with a whitifh duft, which is un- *¢ doubtedly fulphur ; for, by burning:one or more “on an ignited fhovel, or clear live coal, they pro- «« duce a blue flame, and emit a very fuffocating «© {ulphureous {mell. «¢ All that I can learn of the operation of this «¢ water, from fome fenfible people of credit and ‘¢ Obfervation, who have drunk it this as well as for- «¢-mer feafons, is, that it very fenfibly increafes the “ urine, and fometimes remarkably opens the pores; «¢ but I do not find, from the report of any, that it «< purges, though drunk to the quantity of three, « fometimes of four, Englifh quarts in the day. «© Almoft every perfon remarks, that it whets the “‘ appetite, and fits light on the ftomach. T have “* been told by feveral, that they have had head- 2 ‘¢ -achs Lal o [Ax7 | achs immediately after drinking their morning bottle, but of no long duration, nor to any great degree. ¢ It is impoffible to fay with ating’ the num- ber of cures thefe waters have made, or what par-_ ti@@lar cafes have received moft benefit from ufing them; for every perfon in the county pre-- fcribes the water for themfelves, and runs to the well, or fends for the water, for every complaint, acute and chronic. ‘ «° T have indeed myfelf directed feveral people with various complaints to drink them. Some. very foul faces have been quite ¢ cleared ; and, at . this time, a gentleman’s fon, nine years of age, with a herpes round the neck, which had proved extremely obftinate to other means, has got a per- ‘fe cure by drinking and wafhing with them ; and his fifter, a young lady of eighteen, who, from an untoward recovery fr6m the meafles and {mall- pox, fell into a fort of habitual eryfipelas on the face, head, breaft and arms, is now wfing them, and, I think, with evident advantage. Some foul ulcers on the legs, and one with every appearance of a carious thigh bone, have been perfectly cured. And a fervant-maid in my own family, who had been for feveral years, periodically in the winter, afflicted with fevere rheumatic pains in her arms and fhoulders, received remarkable benefit from — this water, one fummer; in fo much, that the winter fucceeding fhe had little or none of her rheumatic pains, and her appetite and digeftion were much improved.” Vor, I XI, D Se [ 18 ] “So far Dr. Mackenzy. From others I have been informed, that this water has been ufed with fuccefs in many of thofe cutaneous diforders commonly called. {corbutic, and in curing the itch. In order to difcover the particular contents of this. water, I began to examine the bottles, which had been fent me, on Tuefday, the roth of September, which was about five weeks after the water had been. taken up from the well. ‘The bottles were all well corked, and the tops of the bottles had been dipt into melted wax fo foon as they had been corked. The water was as clear and limpid as the pureft rock. water. It had ftill a very ftrong fulphureous fmell. and tafte; but it had no other but a fulphureous tafte,, : and it made no impreffion, on the tongue, of fea or any other falt. Some of it was poured into different glaffes and tea- cups, and different things put into each. Syrup of violets became flowly green. _ A watery tin€ture of galls occafioned no particular change of colour, but brought a variegated fcum, of the colour of a pigeon’s breaft, to the furface. A diluted {pirit of vitriol mixed fmoothly, and oc- cafioned no white cloud, nor more emotion or cloud than if it had been dropt into diftilled water, only foon after a number of air bubbles collected at the bottom and fides of the glafs; and the fame thing happened, when fome drops of the ftrong oil of vi-. triol were mixed with another parcel.of the water. Bach drop of a folution of pure cryftallifed na= tive foffil alkali occafioned a white cloud, and a white precipitate fell-to the bottom of the glafs; but. each drop of a folution of falt of tartar caufed a dark brown ~ bed brown-coloured cloud, with a precipitate of the a colour. A fhilling and a fixpence, put into two different tea-cups, were prefently tarnithed, and became of 4 very dark colour, Each drop of a folution of filver in fpirit of nitre, occafioned a dark brown or blackifh cloud, and fell in form of a black precipitate to the bottom of the giafs. Some very white faccharum faturni turned imme- diately black, and precipitated in form of a black powder to the bottom of the glafs. Four pounds feven ounces and fix drachms, (or Ixxi ounces vi drachms) were poured into a ftone bafon, which was put on a fand heat to aA QEAEE with a flow fire. As foon as the water ; heeaae warm, it loft ite {trong fulphureous fmell, and there appeared fome flakes of a dark brown light earth, which dropt to the bottom. After about one half was evaporated, a very thin pellicle was obferved on the furface, which precipitated to the bottom, and when it was reduced to about a pint (lib. i.), it was filtrated through paper, and about 2% gr. of a dark grey infipid fediment was feparated. ‘This fediment was compofed of the dark coloured earthy flakes, which were obferved fo foon as the water had become warm, and of a {mall quantity of a whitith, infipid gritty matter, which had formed the very fine thin pellicle. Some of it being thrown into diftilled wa~ ter, and oil of vitriol dropt into it, an effervef-— cence enfued, and the black earthy part diffolved, though ae reft remained infoluble ; ; hence the firft D2 part, | 20 | part, or black earth, fhould feem to be of the ab- -forbent kind, the other an infoluble earth, or a fe- Jenite. Whether the firft earth was originally dif- foived in the water by means of air, or whether it was - sonly light particles of earth, which had been blown into the well, and only fufpended, I fhall not take wpon me to determine; but, in looking at the water of another bottle, which was not ufed in this ex- periment, I obferved, that although the water ap- peared quite tranfparent, yet that it contained: fome ~ particles of light earth fufpended; however, thefe might have been originally diflolved by means of air, but feparated afterwards. . The remaining water was put into a {mall bafon, and fet again ona fand heat to evaporate; when it was reduced to about three ounces, a pretty firm pellicle appeared, and it was fet in a cool place for twenty-four hours ; at the end of which time, it was examined ; and, befides the pellicle which had formed on the furface, a thin white lamellated and granu- lated cruft had formed, and attached itfelf to the bottom and fides of the bafon. Thefe being all fe- parated, the whole was thrown into a filter; and when the water had paffed, and the coffin was dry, “here was found remaining gr. xi. of a very white, infipid gritty fediment.. This fediment in the mouth feels gritty, and has no tafte, being quite infipid ; when fome of it was put into a glafs with diftilled water, and a few drops of oil of vitriol mixed with it, a very flight effervefcence enfued ; but almoft the whole remained undiffolved, and appeared to be fe- lenite. The B3a504 - (eet. ' 'The'water, being again fet to evaporate, was re~ duced to lefs than an ounce, when it was again fil- tred, and gr. ii fs. of a refiduum feparated. This fediment appeared to be nearly of the fame nature as the former; but, on putting it into the mouth, I thought | could perceive fomewhat, though very little, of a faltith tafte, and when thrown into water, it remained all undiffolved. The fmall quantity of water which was left, was next evaporated to drynefs, and there remained in. the tea-cup gr. xvii. of a yellowifh matter, compofed: of the thin lamelle of fome falt, anda yellow unc< tuous or oily fubftance. It had rofe into blifters, and: emitted a very ftrong {mell of fulphur, while it yet remained hot.. Some of the faline matter, being put into a folu- ‘tion of the cauftic alkali in diftilled water, occafioned a white cloud ;.and the fame thing happened when: fome of it was mixed with folutions of filver in the: nitrous acid, and of corrofive fublimate in. diftilled. _ water. . : } In order to feparate the falt from the yellow oily matter, the fediment was thrown into and diffolved in an ounce of diftilled water, and then paffed. through filtring paper, and evaporated to a pellicle ;. after which, it was fet in a cool place for forty-eight hours, in which time a cryftallifation took place,, and I feparated very near er. xii. of a falt fimilar, in. every refpe@t, to that of Glauber; but it had ftill a: dittle of the yellow oily matter adhering to it. ‘This. falt had a cool bitter tafte ;. it diffolved eafily in dif-. tilled water, and when fome of the native foffil al- kali was. added to’ this folution, it.remained clear ;. " | though: though when a folution of the cauftic vegetable alkali was added, each drop occafioned a white cloud. Some drops of oil of vitriol, let fall on fome of this falt, occafioned no effervefcence, nor raifed any fumes ;. and when fome of it was put on a red hot poker, it rofe into blifters, and did not crackle. From all which I conclude, that this was a true Glauber {alt i After this falt was feparated, the remaining liquor was left in the tea-cup, and, at the end of four days, it concreted into a yellow cake, which ftill contained | a good deal of a falt; it weighed gr. ix. fo that there had been a great increafe of weight, from the water the falts had taken up in their cryftallifation. This matter was extremely bitter, and had likewife a cool- ing faline tafte. Some of it, put on a red-hot poker, melted, and rofe into blifters; it- emitted a little fmoak, but did not fame; and it had fuch a very flight fulphureous fimell, that it was doubtful whe- ther it proceeded from the yellow matter or the ig- nited iron; it burnt to a black coal, which tafted fomewhat faltith. Some oil of vitriol dropt on fome of this matter occafioned very little eftervefcence, but raifed a ftrong pungent acid {mell, which I at firtt imagined muft be that of fea falt; but, from the few marks I have obferved of the exiftence of this falt in a perfect ftate in thefe waters, I have fince thought, that it might be that of a volatile vie triolic acid, which had been formed by the union of fome of the acid of the Glauber falt, with a ful- phureous or oily matter, and diflodged by the addi- tion of a fixed acid of the fame kind, though perhaps there may be a pittance of a calculareous marine falt In [ 23 ] in- the yellow ley mixed with the Glauber falt. Having accidentally added a folution of cauftic alkali to this mixture of the yellow matter, and vitriolic acid, it emitted immediately a ftrong fmell of hepar fulphuris. This yellow matter I take to be com- pofed of a Glauber falt, and a yellow oily matter common to almoft every water, though perhaps in. _ larger proportion in this than in many. others; but whether it contains a pittance of fea falt, I think ts doubtful; and what makes me ftill doubt the more, is my having fince evaporated 44 ounces of the water, from.which I obtained gr. x. of refiduum, when the water was at laft evaporated to drynefs, which I threw likewife into diftilled water, and the moft of it pafled the filtre, and concreted into pure cryftals, refem- bling thofe of Glauber falt, leaving but a very fmall pittance of a yellow oily matter behind. How- ever, it will be neceflary to have a pretty large quan- tity of this laft refiduum, to determine with precifion the nature of every ingredient in its compofition, and the exact proportion of each. , _ Having tried as many experiments as I could, with the {mall quantity of this yellow matter I had, I laft of all examined the coffin through which the falts. and it had pafied. After it was dry, I found that it had increafed gr. u. in weight, and that it was co- vered in the infide, with a yellowith powder.. When: part of the paper, with this powder, was lighted with: a candle, and the flame extinguifhed, it {melt ftrong ef fulphur; and, on rubbing a fhilling with. another bit of the paper, it immediately tinged it yellow, as. pure fulphur would have done... From. whence, I _ think, we have reafon to.conclude, that this powder: One: iP a4.) contains more or lefs of a true genuine fulphur, or, at leaft, of a fulphureous matter. From what has been faid, it appears, that this is one of the ftrongeft falphureous waters hitherto found in Great Britain, though I make no doubt but that there are many fuch which have not hitherto been examined: That, in its natural ftate, it is. highly impregnated with a volatile fulphureous va- pour, which evaporates foon when expofed to the open air, and flies off immediately when expofed to heat; and that the water then lofes its ftrong ful- phureous {mell and tafte, though we have the ftrongelt _ reafon to fufpect that it {till contains a fulphureous matter diffolved in it, by fome means hitherto unknown to us; for it neither contains an alkaline falt nor quick- lime, the two only fubftances we hitherto know to be capable of diffolving fulphur, and keeping it fufpended in water: That it lets drop to the bottom of the well, and of its channels, a fine powder of fulphur, which adheres to the leaves and branches of trees found there. J. As this water contains but very little purging fale, and does not operate by ftool, fea water, or fome purging falt, may be added to the firft glafies drank in a morning, when purging is required. Equal parts of the Caftle-Loed and fea water mixed to- gether, make a water in moft refpects fimilar to the Hatroweate ; and probably will be found to anfwer in moft cafes where the Harrowgate has been found ufeful; and it may often be ufed with more advantage than the purging fulphureous waters, as they fome- times purge people of weak conftitutions too is and weaken them too much. OF 3 [ 25 ] OF the fulphureous Mineral Water of Fairburn. Dr. Mackenzy in his letter mentioned no more of this than that he believed it to be a weaker water, of the fame nature as the Caftle-Loed. . T fubjeéted it to the fame tryals, as it: on opening the bottles, it emitted a ftrong fulphureous fmell, tinged filver, and produced nearly the fame ap- pearances as the Caftle-Loed when’ mixed’ with the fame fubftances, only it remained clear when a fo- ‘ution of the true foffil alkali was mixed with it; the cauftic vegetable alkali occafioned a very fmall light, darkifh cloud, and precipitated but a very fmall quantity of a very light fediment, ow- ing, as appeared afterwards, to this water containing an abforbent or calcatious earth, which probably was fafpended by air, and but very little if any felenite. | T evapotated lib. viii. drachm. 1. {crup.1. (or 128 ounces, four fcruples) of this water with a flow fire. When it was evaporated to one half, it was filtrated through paper; which operation was repeated ‘again, when reduced to three ounces; after which the re- mainder was evaporated to drynefs, and the folid matter left, thrown: into diftilled water, filtrated again through paper, and evaporated to a pellicle, and fet in a cool place for the falts to cryftallife. By thefe operations, I obtained near gr. ii. of a dark coloured light earth, which effervefced with acids, and diflolved; gr. xv. of a white calcarious earth, which effervefced with and diffolved in the vitriolic acid ;—and gr. xxiv, of Glauber falts mixed with a Vor, LXIL, E yellow [ 26] yellow oily matter; but I got no {elenites, nor any matter which coloured filver, or T had any reafon» to: fufpect to be fulphur. Some of the falt was diffolved. in diftilled water, , and different liquors were dropt into. different parcels. of it. colour. occafioned a bluith white claud,. which. fell to the.- bottom... The folution of the foffil alkali mixed clear, as did. a folution of falt of tartar, but each drop of a. folu-- tion of common cauftic alkali gave a. white cloud ; . fome oil of vitriol dropt on a little of this falt effer-. vefced,.and emitted acid.fumes, while it yet was. mixed with a good deal of the yellow oily matter ; . but after the falt was diffolved in diftilled water, and. again cryftallifed, and freed of moft of this yellow , matter, no fumes.were to: be obferved ;-and the acid ; fmell was extremely faint when firong {pirit or il, of vitriol was dropt upon it. . This,, though it.does not. appear to. be fuch' a, {trong fulphureous wateras the Caftle-Loed, yet it. may have its ufes, and. be ferviceable to thofe who . have not an opportunity of ufing the other; and it. may perhaps be ufeful in fome cafes, where the other. may not. agree. ! Of the. Salt Purging Water - of Pitkeathly, in “the. County of Perth, There are but few fait purging waters, which’. have. hitherto been difcoyered in Scotland ; _the., Pitkeatht . Syrup of violets became immediately of a rae Each drop of a folution. of fanless in.the nitrous acid,, | ee Pitkeathly, fituated about fix miles from the town of _ Perth, is the one in moft efteem, and the moft fre- quented. As no particular treatife has been publifhed on thefe waters, and I withed to know their particular nature and contents, I wrote to his Grace the Duke of Athol, whofe feat of Dunkeld is within 14 or 15 miles of the wells, and begged the favour of him, to afk fome of the phyfical people in the neighbourhood to‘examine thefe waters, and to- fend me an account of them; and in confequence there- of, his Grace was fo obliging as to fend me a letter from Dr. Wood, of Perth, giving the following de- {cription of them; and afterwards fix bottles of the water, which arrived in {pring 1771. i «¢ The fpring rifes in a very low marfhy ground, © ea: undiftinguithable from any other; but, by the tafte “¢ of its water, it is generally believed to contain. « no mineral principle, but a fmall proportion of ‘« marine falts. It acquires fomewhat of a putrid — «¢ tafte by keeping, but retains its purging quality; “* and it keeps much better in open, than in <¢ bottles. «* It purges gently, and without griping. An <* adult perfon drinks commonly a bottle and | a half, “< or two bottles, of a mcrning. *© In {crophulous and fcorbutic habits, it is cer- <* tainly a moft ufeful water. ‘ A-new {pring has been lately difcovered about *¢ two or three hundred yards from the old one, but its waters feem to be much of the fame. «© ftrenoth ape quality as the former.”’ . E 2 Since a nv [ 28 ] _ Since receiving the above account, I wrote to Dre Wood, and begged to know of him what propor- tion of fea falts thefe waters contained, and. whether they had any mixture of a bittern in their compofi-. tion; and I had the following anfwer, dated O&. ie a if BR | la «¢ Since I receiyed your letter, I evaporated a: “ Scotch pint (Lib. iv.)}; of thefe waters in a.white- «< ftone bafon, and I obtained two drachms of a << falt, which always run per dekquium,. and, would: << not cryftallife. I fhall try it again. in the fum- | «* mer, as at this feafon the air, being much charged: ‘< with watery particles, may have prevented the. « cryftallifation. By dropping a folution of potafh. «* into three Scotch pints (lib. xii.). of the wattrs,, « T got eighty five grains of a very fine magnefia.” The fix bottles of this. water which: were: fent to: me, arriving at a time when I was much engaged, . they remained for feveral months in. the hamper in, which they were originally packed; and Idid not: try any experiment with. the water till the ad of. October laft. It was then clear and. tranfparent.as the pureft rock water, only it feemed. to have fome: few particles of light earth fwimming through a It had then: a fetid fulphureous fmell, refembling- fomewhat that of a foul gun or of rotten eggs, and: it tinged filver in the fame way. as the fulphureoys. waters beforementioned; and it hada fulphureous and: flight faltith tafte. This. fetid fulphureous fmell,, taite, and property of tinging filver, which this as. well as moft other falt waters acquire by keeping, BP fufpect to be owing to a fermentation taking place in. the water, and flightly uniting fome.of the fine oily: 3 . matter; [ 29 J matter with fome: of the acid of the falts which thefe waters contain, and thus forming a fulphureous vapour which is-volatile while they remain flightly united,. but which by.a more intimate.union would. form a real'fixed fulphur. From Dr. Wood’s ac- count of this water, it is evident that this- fetid va-- pour, or at. leaft the principles which form it, are. volatile ;. for, he fays, the water keeps much better: in open than in corked bottles.. Each drop of a folution of the foffil as well as of the vegetable alkali occafioned a thick white cloud, that fell: to the bottom of the glafs. And each: drop of a folution of filver in the nitrous acid gave. a milky cloud. Syrup of violets became green, and an infufion of galls occafioned no. particular change: ef colour. A hundred and.two ounces, three drachms)and a: feruple (or lib. vi. unc. vi, dr. 3. ferup. 1:) were- put into a large ftone bafon, and {eton a fand heat to - evaporate with a flow fire. As foon as the water. was warm, it let drop a light: dark coloured earth, which gathered in fmall. heaps. at the bottom of the bafon; and during this time,. the water: threw up fome air bubbles.to its furface ;, when it:was evaporated to about a pint (lib. i.) it was . taken off the fire, and filtrated through paper : the cof. _ fin through which. it paffed,. after being dryed, was. found to have acquired :21 grains of additiona! weight s . though I could ‘not collect more tham3 gr. of a ftone- grey coloured earth, which proved to be of the abfor-- bent or calcarious kind, for it effervefced with and dif- - folved:in the vitriolic:acid; the. remaining. additional - weight of. the coffin, .Lbelieve, depended. on {ome of [ 30 ] | ‘the falts of the water being taken up oy the fpungy Ailtrating paper. After this, the water was again fet on the fand heat — and evaporated till a pellicle appeared on the fur- ‘face ; and during the evaporation it threw up a great number of air bubbles : after this, it was fet in acool place for three days, at the end of which time there appeared a quantity of thin lamelle2, mixed with a {mall granulated falt, covered with a light coloured yel- Towifh liquor; thefe I feparated, and threw the liquor into filtrating paper; and by thefe operations I got §3% grains of a Salt which tafted tharp and falt, befides what had been taken up by the coffin, which had increafed gr. g. in weight more than I had got of falt. ‘This falt being put in a tea cup appeared next day white, and had contra¢ted a little moifture, but did not run per delquium. The remaining water which was now a yellowith Jey, was again evaporated to a pellicle, and I fepatated a quantity of white falt in lamellz, which remained ‘moift, till it was fet in a tea cup on the fand heat and evaporated to drynefs, when it weighed one drachm and 14 grains; this falt attracted more moifture than the former, and feemed at firft as if it would run foon per dekquium; but the next day it remained in the fame ftate. As I imagined that both this and the falt before feparated was moftly fea falt mixed with a bittern and oily matter, which prevented the cryftallifation ; I difflolved the whole of both in diftilled water, and evaporated with a very flow fire till a cryftallifation began to appear, and then fet it in a cool place, and got fome large perfect cryftals of fea falt, and by repeat- ing [or J | ing this feveral times, I. obtained a full drachm of | perfect cryftals, which diminifhed in their fize as the procefs advanced; and afterwards a fcruple more of | thin lamellz, which on examining with a magnifying. glafs appeared to be made up of {mall {quare cryftals ; there remained a {mall quantity of afalt ley, which probably would have yielded a few more fuch lamelle, The liquor which remained after the two firft parcels of falt were feparated, was next evaporated ; but no pellicle appearing, the operation was continued _ till it was quite dry,. when it formed one tranfparent yellow or amber-coloured falt cake, which weighed one drachm and 34. grains. ‘This falt on being put into a tea cup, prefently began to run fer deliquium, and diffolved entirely by ftanding in a cupboard which was in.a room. where there was a fire ; but the fire having been. let.out inthe evening, and. the night — proving cold, I found next morning that a cryftallifa- tion had taken place, for there was a cryftallifed cake - at the bottom of the cup, which was covered with an: amber-coloured ley ; it at firft feemed to be all one ‘piece, with a number of. {mall points.ftanding up on, its furfaces ; but on reclining the tea cup to a fide, it then appeared to be made entirely up of a number of oblong cryftals about the length of a barley-corn, but not fo thick, and. that the. points beforementioned. were the ends of thefe cryftals. Not having time to. examine them particularly in the morning, and to.. know their exact figure and number of fides, I fet them by, till I fhould come home. again. about one. o'clock ; but the day proving warm, they were moft-- ly diffolved before that time. Oil of vitriol, dropt into a tea cup in which there - was fome of this ley, immediately occafioned a white net frm. [ 32 ] } &rm coagulum like chalk, which was infoluble in wa- ‘ter, and, when well wafhed and freed. of its acid, felt ‘gritty and was quite infipid in the mouth; this is certainly a felenites formed by the earth of this ley -and the vitriolic acid. RE . From this account of the Pitkeathly waters, it ap- pears that lib. vi. unc. vi. dr. 3. fer. 1. befides a few grains of an abforbent or calcarious earth, contain three drachms, 41 3 grains (befides what was loft in filtrating and other operations) of a faline matter, of which near two thirds were fea falt, the reft a bittern or falt with an earthy bafis, which concreted by the force of fire into a yellow faline mafs, that’ runs foon per deliquium, and cryftallifes though with dif- ficulty. | The {mall quantity I had of refiduum prevented amy being able to determine with precifion, the exact proportion of fea falt and of this bittern; neither was I; for the fame reafon, able to determine whether this bittern or ley was all made up of a calcarious marine, with an oily matter common to all waters, or whether it contained likewife a fal catharticum amarum with a vitriolic acid. From the acid of vitriol forming an infoluble fe- lenites with the earthy bafis of this bittern, it is evi- dent, that at leaft all the earthy bafis is nota mag- nefia, fuch as makes the bafis of the fal catharticum amarum of the fhops, or what goes by the name of Epfom falts, otherwife it would have formed a falt eafily foluble in water. LV. Extraé {33 ] “yv. Extra of a Letter from Mr. George Witchell, FR. S. and Mafler of the Royal ee at Portfmouth, o Charles Morton, MM. D. Sec. R.S. inclofing fome Account of a Solar Eclipfe obferved at George’s Ifland, by Captain Wallis; and jeveral Aftronomical Observations made at ~ Portfmouth. . “To Cha. Morton, Sec. R. S. &e, SFR Read Feb. 13, Qf Beg the favour of you to jay before ie l the Royal Society, an extract of 2 letter to me from Captain Wallis, containing an ob- fervation of a folar eclipfe, which happened during his ftay at George’s Iiland, from which I have cal- culated the difference of meridians between that place and Greenwich. To this 1 have fubjoined fome aftronomical ob- fervations, which have been made here by Mr. Brad= dey and myfelf, -both ‘before and fince the building ‘of the Obfervatory belonging to the Academy; which, if they fhould prove acceptable to the Royal Society, will induce us to take every opportunity of Vou. LXE. F con= | £34] continuing to tranfmit them, as we ‘hail always efteem it a peculiar happinefs to be able to contri- bute any thing, that may be deemed worthy of their notice. lam; SIR, Your moit obedient, humble fervant, Royal Academy, Portfmouth, Augull 95,271 G. Witchell:. Extrat of a Letter from Captain Wallis, June 2oth, 1771. «¢ Saturday, July 25th, 1767, being at «© anchor in his Majefty’s fhip Dolphin in harbour, «< went on fhore on a low point of land, not above «* four feet higher than the fea, and obferved an « eclipfe of the Sun, as below. Latitude, by the~ «© mean of many obfervations, 17° 30’ South, lon- © ¢. gitude, by various obfervations of the diftance of «the Sun from the Moon, between 449° 30’ and « 149° 50’ Weft from London. « By Ef a5. ] Bie G2 « By the mafter’s watch at 7 6 0o1]A.™M. the @’saltitude was 8° 43 on the so neal 4 es «By my watchat . » 7 3 20 without any correction. Hence the app. time 5 _ & By the mafter’s rare at 13 @. M. the @’s altitude was 22° 52’ on the quadrant, aes H h ; } 8 12 12 « By my watchat . . 8 10 12 without any correétion. ence the app. time : The eclipfe began, by the mafter’s watch, at . 6 52 30 By my watch, at - »« . + Se pnes sabe yi OE OU pad Nad? By my watch, ag fey Mau rer. Let tte OL LOR 5G The end of the eclipfe, by the males watch, at 8 1 te Me: a. M. Apparent time, 6 51 50 Ae is Cael “© Duration 1 9g 10. _ * We were not certain of the inflant of the beginning of ue eclipfe, from a little negligence ; but _ *© very certain of the end.” : ; REMARK, As the Sun’s altitudes are given, without any correction, I fuppofe they were taken by bring- ing down the image of the Sun, till it appeared bifected by’the vifible horizon: I have therefore recomputed the time, by allowing for the dip and refraction, which, together, amount to 8’. This Soule ates. makes the apparent Hime of the beginning 6" 51’ 12”, and the end 8' o/ 37’’; hence the du- ration of the eclipfe was 15 9’ 25’’3 but, by a care- ful computation from Mayer's. new Tables, the du- ration fhould have been 1° 13’ 20/1, which is al- , B 29 moft about 4 longer than the obfervation affords ; but, as it is remarked that the beginning was not exactly taken, and the Moon entering very obliquely on the Sun, the defect in 4’ would be but little. It _ feems moft reafonable to attribute the whole of the error to the beginning of the eclipfe. I have there- fore deduced the longitude from the end, and F 2 make ee make it to be 9" 55’ 55’ Weft from Greenwich, or 148° 58/3, which. is 41’ lefs than the mean refult: of the lunar obfervations, which, confidering all- cireumftances, is not; in my opinion,.a very great- difference for the firft obfervations that were ever: made upon this ifland, Aftronomical Obfervations made at the Royal Acas- | demy,. Portfmouth. — 1769. May gth, at 8213’ 9”, apparent time, Mr.. Bradley obferved the immerfion of € ][°™™ -by the - Moon, uncertain to a few minutes, on-account— of the {trong twilight.. The emerfion was not: taken. fais The tranfit of Venus, and folar eclipfe,. next morn~ ing, were both obferved here; but, having then no better inftrument for determining the going of | the clock, than an indifferent Hadley’s fextant, I do not think the obfervations-worthy-of being laid. before the Society ; and, for the fame reafon, omit: the obfervations of the comet; 1770, April 7th, at rt? 23’ 33”; apparent time,-, by Mr, Bradley’s obfervation, the Moon occulted : 2-9.8.. My time-was within 2” or 3” the fame; . but we did not obferve the emerfion.. This oc- - cultation was obferved both at Greenwich,. by Mr... Maikelyne, and at Oxford; by Profeflor Horntby; . by comparing which, it appears that this place is _ Weft of Greenwich. 4’ 24’’2: of. time, and ; that - Qxiord is Weft of Greenwich 4’ 58’’2. x I 77 Oa [ 37] 1770. April 28, at 9? 48’ 13/’, apparent time, Mr, Bradley and.1, both at the fame inftant, obferved | the inamerfion of £8! by the Moon... The emer- - fion was not taken, | By comparing this with Mr. Matkelyse’s- obfervation, our longitude comes out : 4! 23!’ Weft from Greenwich. . 1779. July 21ft is marked for an eclipfe of Juptiter’s fourth fateHite in the Nautical Almanac; but the - Connoiflance des Temps notes it as a conjunction enly, and remarks, that the fatellite would rafe- the fhadow, . without difappearing ;, which we - found to be true, for we both’ teat the fatellite- the whole time which is ‘marked for its dura - tion, though,.at the middle, it apse extremely pine) ~ ‘Thee obfervations were made before our Obfer-- vatory was finifhed ; but that being completed in the - month of September, and furnifhed with an‘excel- lent (though fmall) ‘mural quadrant ‘and tranfit in-~ ftrument, both made by that eminent artift Mr. John Bird, .we began to obferve meridian: tranfits, from’ ees whidt T fhall feleét thofe that: were made. Hee deter-* mining the folftices, and the oppofitions: of the three » fuperiour. planets,. which I fhall tranferibe, juft as.. they. were.taken, excepting. only’ making the: ne«:- cefiary allowance for .the. error.of. the tee of cole ‘Himation.:. 4 Obfervations - I 38 } Obfervations for determining the Solftices. | \pp. zen, dift. App cent dift. “Baloy { Thermon Hence the app: fthe Q's V.L.Jjof the ©’sL.L.} meter, | meter. zen. dift. of the Sun’s center. fo} r it C) U ° Ud it 1770. Dec. 9g. |73 21 40.3173 54 73 37 52-7 12.173 36 41.8174 9 73 53 3-4 14.173 44 22.0174 16 |74 .0 40.1 21. |73 $6 41.0174 29 | 74.12 57-0. 22.173 66 20.0174 29° 74 12 44.0 29. 173 42 27-2174 15 73 58 43.8 17 71- lee 3. 13 SNOW LO.O} Fs ugit 3 73 34 40.8 1771. June 8.427515 4524127 939 127 21 43.8 19,127 4 52-7 27 36 27 20 42-4 20.127) erie Oe goa 27 19 48.2 BV6AZ7 + 3)'33.6 129 35 27 19 29.8 22/27 3 §Y.0|27 35 27 19 40.2 BAL AZT GL iarint | 29. 3 27 21 10:3 Beta Opnaeano7 ae 27 22 37.6 aS art 7 ; ; By comparing thefe obfervations together, ITmake the) ° ’ /” ~ true zenith diftance of the Sun’s center, at he 16) 13.4 + Winter!Solitice,: tovbe i's wet, to ee ih) os eet ea ge nd at the summer QolltiGe 800. | Ae Ne ) 6) Pee LO CI Therefore, the diftance of the tropics . . «+ « 46 56 21.8 _ Half 23 28 10.9 By Mr. Mayer’s Tables, the decrement of the obli- | quity, in three months, is . 5 3 6 6 6 wef me Hence the mean obliquity, December 21, 1770 . 23 28 if.0 And sJune 215 7710608 SURO. Sel I DRA e339) 2B) fO.8 Thetefore, the latitude of the Obfervatory, by thefe| __ : Oblervatlons; 485 Nie Wet} eae h etl whe aye anes f°? 48 2.4 North. The above obfervations were chiefly taken by Mr. Bradley. Thofe which follow are what I took about the time of the late oppofitions of the fuperior planets, in which, as well as the preceding obfervations, the apparent zenith Gillances are thofe which were taken by the 96th arc, on which we chiefly depend, though the difference between the two arcs feldom arifes to more than-three or four feconds, For [ 39 J For the Oppofition of the #% and ¢. Meridian Tranfits. 5 18 582 |8 Leporis paffed the middle wire. 1770. Dec. 10. 20 5i—|> Orionis. BO, 46-1) Mars, 67 07 os Rieimtce ces.: (24 (419 9G.01, 20,87 43 19 |a Orionis. es 13. | § 12 24—(6 Tauri. | Br 35 Mars qe sthionte chet aos >, 2 (2420.1 1.41.20,76| 42 43 21-+\« Orionis. | -6 1.37 |» Geminorum. | i 1624) 5 26 222°) Maras. wisi) los set giie, + 124030).55-5 | 29:80 43 21 |e Orionis. : 17, | 5 12 24% (8 Tauri. 24.40 iMarsy i teiadacchi iy sties S0y ig e301 5.6)) 2o.01 ie, 43 21 |a Orionis. : z0o./5 4 7—| Rigel. ‘in Spee AO epi BATS. sins a uplivin sinen tian seine i2de, 30, 2500], 2OvLOT Ag 37 29+ pe Orionis. t For the Oppofition of the #3 and h. Time per clock. Meridian Tranfits. App. zen. dift)Barom. ee rn rn rr rr ee fe a h / Wf Ome W g 1 51+} Satusn paffed the middle wire. [32 48 20.81 29.89] 42 16 26—|¢ Hydra. 9). -1. 32 Saturny il ee eg che, 122, 4615 74 | 30:07 | 42. 16 262 ja Hydre. ; 8 32 58+. Leonis. : i ik 59 G75 |. Satu eee ise ice eS NSS 30 \2U.G4 40.044 28 Fg 29 4-+fo Leonis. Fant Therm. Days. b77t. Febr.° 1, ee Se es ae Gem eee | ee fe ee EE 1o. | 8 sq 12} Saturn Les) PR Le 32 35 182 g 10 32 |x Hydra. 29 5+19 Leonis.. Ot rr tre a re < = ‘For the Oppofition of &% and ¥. ee per clock. Meridian ‘Tranfits. — | Appy zen. dif |; ssa ensarecmans Leen fuk Paige scald o Do a 1771. / July .12, |16 15.41 Antares paffed the middle wire. g 13 “oO 272 | Sagittarii. = 9 44-—)7 Serpentis. ‘r4 92 A Sagittarit, 9 39 gz ‘Jupiter OG gee Th epee Cen Onmees figs. 7 Bean ee |S aene limb. 41 8+] °.©’s following limb. {19 38 34 Papier c+ ee le 53 z go-18 st oe eee tee et eens Sac 6 14: [67 32°53 | .©’s preceding limb, 35 tro+} ©’s following: Hey 419 37 59 Jupiter Ss CRC Ma nt Fa Soe ey a ag | ee es cane) SS SS a —~ hag Ge Ghace 2) \@2s Eadack limb. 39 #2. | +O'%s following limb. “476°15 35--] Antares. mye 8 1043723 depicey FV EMME oko oak Baa Ae 44 57.1] 30-12] 59 .17. | 7 44 56-—| ©’s preceding limb. 47 12-+| ©’s following limb. +|t6 1§ 31 Antares. 19 36 145 Japiter sss ss 8 172 47 50-7] 29:92 65 Neue | 88:46 ©’s preceding limb. ‘11 oF | ©’s following limb. {16 15 192 | Antares. 60# “49 32 43 Jupiter’ s FREE ve) 42 58 47.31 30031 An Occultation of a Libre by the Moon, | App. time. Day. h Be ue wi7zi. April 2, atltz3 7 9% | a Libre emerged from the Moon’s limb, Mr. Bradley makes the time ee fee se Use a) was not’ qe — The 3 4 Be Tar] "The Moon’s Paffage over the meridian, near the 6, Time per clock. Meridian Tranfits. App. zen. dift. vs the >. Barom. Therms Dayle io) 8 Me- x77. April 28. 2 tg 54 |Sun’s srecenial ast A : 429.744 44 ~ | paffed the fecond wire|’ 24 4 San’s following limb ; ’ pafied. the fourth wire . {34.17 23-+|Moon’s preceding limbj paffed the middle wire'Upper limb 66 13 19 40-+/Moon’s following woke eon a Ge 45, ee It Raine very clear this evening, ee the Moon’ paffed ‘the ‘meridian, we were in hopes of getting a good obfervation of the lunar eclipfe, which happened foon after ; ; but the air did not long continue in that ffate, but became fo hazy, that we, could, not. Be any certain obfervations. 7 , Vou. Lx IT, G V. Extra [42 } V. Extraét of Mr. 'T. Barker’s Meteorolgi- cal Regifier at Lyndon im Rutland, in a@z Letter to ee Welt, Eig uke R, S.. © Re, Have, according to your defire, fent- you, on the other fide, the quantity of rain which fell laft year, and: have added an ab-. {tract of my obfervations of the barometer and ther-. maometer, anda-generalaccount.of the weather here. . And, with all proper, regard, , Read Feb. 13, L772 Lam, SIR;. Your humble feryant,. ~ Lyndon, . Jan. 18, 1772. T. Barkers : Barometer: [ 43°] Barometer. at | Thermometer. W3 “ | Within doors. ot Ce ee riche. | Lowett. | Mean. ‘High. Low. Meant Tigh. Low Mean. Mori 93| 36 6 7 jan {U0 Vay. [870 [any | a2 22 | 58 | 3,1 4 Feb, { Mom [i 48 | 27 | 38 1 43 4] 29 | Feb. | Be iis | 28.96 | 29.58 i 20 | 39 || so.| 25 | 39 orn. B 23 ¢ AOS sy ‘ Mar. |, act } 29.96 | 23.97 bean ge a i peal sp a | jy J Morn. | 501 37143 44s) 25 134i) oe | eae Ke Lael ea 5] 373) 45.11 03, |, 33,40 i J Mora 2145 | 542] 02 | 40 | 503 May | Aftern Ie B4 129 04) 29-49 64 46 56 1} 76 | $0 | G2 Morn. ||, | 624 52 |. 67.4 eo) 404g 2 ed eh: J Oy 29-895 1 Be ie 59 i 50 | O13 Vv me ¢ 5 5 Joly | tera. 412994] 2944 129" Hh coal o> | 65 77 | br [end Morn. ||... 2 64 | 56} 50% 622 4621 54. Aug | Aftern. i 5 }29-07 | 29-48 7oh 57 pa 764) 56 | 652 Sept | arene | 39:09 poe 29.62 E a, x - 2 ia 06. {Ma I sons [anss lous S| | NE|8 B _ { Morn | 24 401 46 ll 642) 26 33° ad | Aftern } ae" Mie OT" || 533] 41 | 40 |) 56.) 343 4 : om | | 3 a | 50. | 40] 44 |] 493! 253) 383 prs Alters $79 fag ‘34 |29:22 1 foil 40 | 44 |} 50] 354] 44 “That very wet feafon, the laft quarter of 1770, ended about Chriftmas, and except three or four warm days, with fome thunder, the beginning of January 1771, it was frofty cbove another | quarter of a year. No froft, indeed, continued fteady much above a fortnight together, oo they were remarkably darp, (part cularly Febrvary 12, the Thermometer abroad was lower than I have feen it in above twenty G 2 _ yearse,) [ 44 ] years.) ‘The intervals between the frofts were fhort,. ae often frofty mornings, and a fettled froft as late as. the end of March; fo that there were but few morn= ings, till April 20, but were more or lefs frofty.. The effects were, that garden-things, turnips, &c.. were very much deftroyed; bays, arbutus, myrtles,. fig-trees, and other tender things, were killed down: tothe ground, and even moft of the common furz ;. and there were fcarce any figns of {pring to that time, and the winter corn was very thin. . Then the weather grew milder, and in May. warm,. and there came a pleaiant, but cool and dry, fummer, and often windy; fo-that the grafs was fhort, and: the crops of hay {mall.: but whether it was from the ground having been fo foaked in winter, the coolnefs : of the funrmer,. or two fine rains in the-middle of: June and Auguft, the ground was. never fo much: burnt as it fometimes is. Every thing was,. and con-- tinued, a8) backward ; the hotteft:part of this fum- gmer was the middle Me July ;. after which; though, there were feveral fine fhowers,. the ground: con-- tinued to burn till toward the middle. of Auguft, when fome rains made the grafs to grow again ; yet: it began rather to burn again,. in fome places, in Sep-- tember, ‘The harveft was very. late this year, efpe-- cially the wheat, which both eared and ri ipened afrer - the barley, and. moft of it was: reaped. in September, Both hay and harveft were well got in, and the.crops; were well eared, but much-of the wheat and rye con-- tinued very thin ;. which .was too much to be. feared, , after fo bad a feed: time, and fevere a winter. : OGober was a wet.and windy month, but that did: aot hurt; after fo dry. a fummer, The wheat feed: time - Pgs s (as: J time was very fine; and the end of O&ober, No-- vember, and part of: December,. were chiefly fair, fine and.mild, faving much of people’s:fodder, which, is fcarce,.and the ground is much drier than ufual at the time of year. (On the other hand; in fome parts. - of Northumberland, Cimberland,, and Durham, there were at this time fome. {uch terrible rains, as- made- prodigious: and deftructive floods.); It con-. tinued open and: mild to the end of the year; but: part of December was wetter,, making. the groundi dirty,, yet.not deep,, 3 Vi Directionss ee WI. Direttions for ufing the common Nie crometer, ‘token from a Paper in the late Dr. Bradley’s Hand: WrILING 5 commini- cated by Nevil “Mafkelyne, ee ronemer iRoyal, and Fy she So. Read Feb. 30, BW AFICROMETERS, as fir con- PLN trived, being only adapted to th ‘mealuring finall angles, as the “diameters of the jun ‘and Moon, or other.planets, and taking the diftance “of fuch obje@s as appeared within the aperture of ‘the telefcope at the fame time, were not of fo ges ‘neral ufe as’thofe which are contrived not only to -anfwer the ends that the firft inventecs aimed at, ‘but likewife, to take the difference of right afcen- ‘fion and declination of fuch objects as are farther ‘afundee than the telefcope will take in at-once, but which .pafs through the aperture of it at:different ‘times. Mr.-Caflini farft made ufe of threads inters fecting one another at half right angles for deter- ‘mining the difference of right -afegneiae and decli= ‘nations of objects near the fame -parallel; and this apparatus being fimple and -ealily procured is of ‘very great ufe to fuch as are not provided with a mi- «crometer made according ‘to the late improvements. ‘But, where fuch a one is at hand, that method how- “ever-curious Heed not-be made-ufe of, the micro- «meter ~ [a7] meter ferving for the fame purpofe with greater exs- aétnefs. It was for this reafon: indeed that the latee alteration in the form of. the. micrometer was made;. they being. before: not fo convenient: for making: ‘f{uch . fort. of obfervations, both: hairs. being. ufually moveable, and:no provifion being made: for fetting - the hairs. parallel:to the diurnal motion .of the ob- jects to be obferved;. both which: inconveniencies « are avoided -in the. prefent micrometers. . The micrometer, .as: now.contrived,. is not: only: of .ufe.in; meafuring. fmall. angles or diftances - be-- tween fuch objects as appear within the aperture. cf. the.telefcope at the fame time,.. but likewafe in. taking: ; the difference of right afcenfion and declination Aa tween flars and planets,.&c. which in their apparent : diurnal. motion follow. one another. through ‘the tele- - {cope. if kept i in the fame fituation. In making ‘the firft kind of obfervations, turn. the (hort tube neh carries the eye. glafs-and. micrometer, &c. -till the: crofs thread (or that. which. cuts-the parallel threads . at right angles) lies parallel to aline pafling through the objets. whofe diftance. is-to be measured, and. then. by. raifing-or.deprefling the telefcope. by help: of the ftand bring the objects to: appear upon: cr, near the crofs thread, and one.of. them juft to touch. the fixt parallel thread: then turn the index.of the: micrometer. till the moveable. thread touches the other, objet, and. the number. of revolutions. and= parts -of.a.revolution; fhewn..by. the index, turned: into .minutes. and. feconds: by the table ‘made as: hereafter: dire€ied,. will. be the apparent angular: aiftance of thofe. ‘objedts. It. is here ae that: the. threads exactly clofe, fo as to touch each: other: " ~ yehenua te | ‘when the index Aands at the beginning of the divi- ‘fions: for, if they do not, there muft be an allow- -ance made in every obfervations to avoid which, it is always beft to adjuft the threads to the beginning of ‘the divifions when: ‘they are firft put on; tor which purpofe ‘the holes in the little plate which carries ‘the moveable thread are made oblong to give room to move it as occafion requires, before it is pinched hard by the fimall ferews which faften it to the ‘moveable arm, ‘through which the long {crew paffles. _ he other parallel thread, which 1 ean the fixed one, mutt be firft adjufted by fetting its edge exactly over the two marks made on each fide the fhort diameter of the aperture in the broad plates, and the -crofs thread muft be likewife fet to agree with the “{trokes: made on each fide-the longeft diameter, and -then the interfection of the crofs thread and the fixt .parallel one will be the center of the motion given ‘tothe .euter plate of the micrometer (to which the ‘great {crew index and threads are faftened) by the ‘worm, by turning of which the fixt parallel thread may eafily be made to lie parallel to the apparent ‘motion of any object in order to take the differ- ence of declination and right afcenfion from any ‘other that follows through the aperture of the te lefcope. . This contrivance is of very great ufe to make ‘a ftar, -&c. move true along the fixt parallel thread, which’ 4s abfolutely neceflary in order to take the’ true difs ‘ference of right afcenfion and declination ‘between - at and any other that follows. Without this contri+ vance it is very difficult to make a ftar move exaétly’ ‘mpon the thread, and it-can only be done by re~’ peated [ 49 } peated trials, which may fometimes take up a great deal of time. If therefore a ftar is made to move on the paralle J thread juft at the crofs, and (the telefcope continuing fixt in the fame pofition) it 1s afterwards near its - going out of the aperture found not to be upon the thread, that muft then be brought to the ftar by the help of the worm, and then the thread will lie parallel to the diurnal motion of the ftar in that part of the heavens, and confequently the crois thread will reprefent a meridian, and the others parallels of declinations, and the difference of time between the paflage of the ftar at the crof$ wire (ues was made to move along the thread), and the tranft of any other ftar, &c. over the crofs thread which reprefentsa meridian, turned into degrees and minutes, will give the difference of right afcenfion And, if the moveable parallel thread be brought, by turning the index, to touch the other ftar about the time of its paflage over the crofs thread, then the number of revolutions and parts thewn by the index (turned into minutes and feconds of a degree by the table) will be the difference of declination between the two ftars. If the ftar is made to pafs along the fixed” thread fo as to feem perfectly bifeéted, there mutt be an allowance made for the femidiameter of the thread or wire, becaufe I fuppofe the index*to be adjufted as before to the inner edges of the wires; but it may, if it is found convenient, be adjulted to the middle of the threads, or elfe correction may be made in the obferved diftance. ‘ ~ In taking any angle, it is convenient that each of the parallel” threads be about the fame ditence frem Vou. LXIl. se the fg] the middle of the aperture of the eye- olafs ; and for this reafon the whole micrometer is contrived to. inde to arid fro; as the cafe requires. The fame motion is alfo of ufe in taking the difference of right afcenfion and declination, by fliding the fixt parallel thread (on which the preceding flar is brought to move) towards one fide of the eye-glals for by that means a greater angle may be taken in between the parallel threads, if need be. And it muft always be remembered that che motels parallel thread fhould be fet either north or fouth of the. other, according as the follo owing ae is expected to be really foath or north of the preceding. In making an obfervation, either the i inner or the outer edges or the middle of the wires may be brought to touch the objects; but then, it muft be remembered to allow fomething for the thicknefs of the wire, in cafe the obfervation be not made from that part to which the index is adjufted. In ob- ferving the diameters of the fun moon or planets, it may periaps be moft-convenient to make ufe of the outer edges of the threads, becaufe they will ap= pear moft difting: gat quite within the mb of the planet; &c. but if there fhould be any fenfible infleGion of the rays of light in pafling by the wires, this would be bef aooecd by ufing the inner edge of one wire and the outer edge of the other. And in taking the diftance or difference of declination : etween two ftars, é&c. the middle of the threads . y perhaps be moft convenient: but, however the. ia pean is made, due correction muft be allowed tor the thicknefs of the wire, if requifite, is The Pst ~The difference of declination of two ftars, &c. may be obferved with great exactnefs, becaufe the motion of the flars is parallel to the threads; but in taking any other diftance, the motion of the ftars being obli lique to them is a great impediment, be- caufe if one ftar be brought to one thread before the eye can be directed fo as to judge how the other thread agrees to the other ftar, the former muft be fomewhat removed from its thread, fo that in this fort of obfervations the beft way of judging when the threads are at the proper diftance is by fre- quently moving the eye backwards and forwards from one to the other: this method muft chiefly be made ufe of when the diftance of the objects is pret- ty large, and the motion or rowling of the eye great. " The micrometer is fo contrived that it may be ap- plied to tele{copes of different lengths ; but then, there muit be a table for each teleicope, by which the revolutions of the ferew may be turned into minutes and feconds of a degree. ‘In order to this it is ne- ceffary that the threads of the micrometer fhould be placed exaétly i in the common focus of the gee glafs and eye-glafs, that is, where the image of objects feen through the telefcope are diftindlly formed. ‘The readiett way of doing this | is, firft to flide the micrometer into the erooves fixt to the fhort brafs tube, which carries the whole apparatus of _ eye- gals, &c, and then to draw the ye elais out by means of its fliding work, till the thread vor Lhe wi crometer are in its focus, which is known by their appearing moft diftin, &c. Then thrift the thor: tube before- mentioned into its proper place, as fa: Fi 2 as wai a fe) -as the thoulders of the brafs work will admit, and place the objeét glafsin its cell, and looking throught the telefcope at tome very diftant object flide the wooden tube in or out till yeu make the objeét appear moft diftin@, of till it has the leaft motion npen the threads when the eye is moved to and ~ fro; for then the threads of the micrometer will be in the common focus of both glafles, and that will be the proper diftance that the object-glafs ought always to be at from the threads; and there fhould be made fome mark or ketch in the wooden tube in order to fet it always at the fame diftance. _ The proper diftance of the threads from the ob- jeQt-glafs being thus fettled, the table for turning the revelations: &c.. of ne {crew into angles or minutes and feconds of a degree may be made fe- veral ways; but as good and eafy a method as any 1S carefully to ae how many inches and parts of an inch the objeCt-glafs is diftant from the threads, and with the fame ic cale to find alfo how many inches and parts of an inch an hundred, &c. revolu- tions or threads of the {crew of the. micrometer are equal to: then, ‘making the firft diftance radius, the laft will be the fine or tangent of an angle an- {wering to 1co revolutions. And having the angle anfwering to 100 revolutions, the a fumber will be eafily known and {et down in the able, as alfo the parts of a revolution; for in fmall angles, fuch as can be obferved with he microme= op their fines tangents or cords are’nearly in the ame proportion with the angles themfelves, ‘The difance before-mentioned (to be ufed as radius) ought ftri€tly fo be taken from the threads. to a point ce, bas me > [53 ] doint within the objedt-gla about one third of its thicknefs from that furface which is towards the wires, if the glafs be, as ufual, equally convex on both fides; but if the focus a the obje&- glals is pretty long and its thicknefs not great, the error that can arile by meafuring from any part of the object- -glafs will become ion tible as to the altera- tion in the angle. The table for the micrometer may. hkewife be made by fetting up two marks at a diftance on the ground, and obferving with the micrometer the revolutions, &c. which they fubtend when. feen through the telefcope, and then computing the angles thofe objects fubtend at the object-glafs, by meafuring their diftance from each other aed fork the obje ela The like may alfo be done by opening the threads to any number of revolutions, and then making a ftar move exactly upon the per- pendicular ieee and noting the time it is pailing from one parallel thread to fhe other; for that time turned into minutes and feconds of 2 degree, by allowing for the ftar’s declination and going of the clock, &c, will be the angle anfwering to the num- ber of-revolutions; from which the whole table may be made. ‘Ehis method perhaps might be mott advantageoufly practifed 1 in itars near the pole, where the apparent motion being flow a fecond in time will aniwer to a much faalice angle than towards the equator. But I believe, upon trial, the firft method will be found moft eafy and praca ticable, efpecially if the fcale made ufe of be well divided, VII. 4 [ 54 ] VIL. 4 Letter from Ms 7: Jolin Reinhold Forfter, fF. R. S. to William Watfon, M.D. giving Jome Account of the Roots ufed 2, the Indians, im the - Neighbours hood of Hudfon’s-Bay, to De Porcupine Quills. N° 2, Somerfet Stable-yard, Strand, Jan. 16, 1772- MONG the curiofities prefented f-%& by the Hudfon’s Bay Company te the Royal, Society, is a {mall parcel of porcupine quills, dyed by the wild natives, fome red and fome yellow, together with the roots Oe fome plants hey ufe for that purpole. I examined them careially, at your defire, and found that they are probably of the fame kind with thofe mentioned by Prof, Kalm, vol. iii, p. 14. and HOG of the Englith tranflation. The one root, dying - yellow, is called by the French in Canada, Tifavoy- anne jaune; the other, dying red, has the name a eaves rouge. . Prof. Kalm declares the Jatte o bea new plant, belonging to the genus of Cue and Gs by De. lepinens in ie Species Pigs trum,; p. 153. by the fpecific name of Tinctorium, D RE We) “y [55] ‘on account of its dying quality. It grows in woody, moift places, in a fine foil, Kalm obferves, * that. «¢ the roots of this plant are employed by the In- e dians in dying the quills of the American Por- ‘© cupine red, which they put into feveral places of « their work: air, fun, and water, feldom change «* this colour. The French women in Canada ‘¢ fometimes dye their cloth red with thefe roots, «© which are but fmall, like thofe of the Galium ‘* luteum or yellow bediteaw.” Dr. Linnzus deferibes this plant, as having fix narrow linear leaves at each knot of the ftem, and four at the branches; commonly two flowers are on each ftalk, and its feeds are {mooth. The roots, when dry, are of the thicknefs of a crow quill, brown on the outfide, and of a bright purple red, when broken, on the infide. The fecond plant, or the Tifavoyanne j jaune, “1s according “to: Prof. Kalm, vol.-ii: p. 160. « the “ threeleaved Hellebore (Helleborus trifolius Linn.) . ‘< grows plentifully in woods, in moffy, not too wet, ¢ Dlaces. Its leaves and flalks are employed by the «© Indians to dye yellow feveral kinds of their work, « made of prepared fkins. The French learned ** from them to dye wool and other things yellow * with this plant.” Among the roots fent as a fpecimen from Hudfon’s- bay, 1 found feveral leaves, which I feparated, and found the plant undoubtedly to be the threeleaved Hellebore. _In the 4th vol. of Dr. Linnaus’s Amoenitates Academice is a figure of this plant, which upon comparifon I found by no means to be accurate: for the [56] the leaves in our fpecimens, and in thofe collected by a gentleman who favored me with the fight of the ‘plant, are far more pointed, than in the engraved figure. ‘The ftalks have conftantly but one flower, The dyed porcupine-quills fent along with the, roots from Hud{on’s -bay, are of the brighteft red and, yellow: and this circumftance faggelted to me the thoughts of trying whether thefe roots mig ght not be ulefully empl oyed | in dying. [ mentioned it to you, and was encouraged to make fuch a trial, as the final quantity of the roots would permit. I boiled a piece of flannel in a folution of half fale of tartar and half alum: the wet flannel was hereupon put into the decoction of the threeleaved. Hellebore-rcots, and boiled in it for the {pace of about 120r 15 minutes; the flannel, when extracted, was dyed with a bright and lafting yellow dye. 3A white porcupine quill, boiled in the fame decoction; became nearly of as bright a yellow, as thofe fent over from Hud{fon’s- bay. This experiment made me believe, that I had hit upon a right. method of dying with the threeleaved Hel lente ; and will, IT hope, prompt the dire€tors of the Hudfon’ s-bay Company to order. larger quantities of this root from their fettle men, it will no doubt become an ufeful article of commerce. The flannel, boiled in falt of tartar and alum as above-mentioned, was likewife immerfed and boiled. for nearly the fame fpace of time as in the former’ experiment, in a decoction of the root of the Ga- lium Tin@orium, but it ‘would dye only a dull and faint red. A porcupine quill boied with it be- came yellow, but by no means red. This opera- tion bs Loe |. tion convinced me, that the Indians-muft certainly have fome inethod or other to extra the bright and lafting colour, which I could not perform, They ufe perhaps the root quite frefh, which circum- ftance probably makes them facceed in their dying procefs. If it could be brought about, to extract and afterwards to fix on wool the dye of this root, it would, no. doubt, on account of its bright colour, be a alee acquifition for our manufactures + and I. do not in the leaft doubt of the probability to fuc- ceed in the attempt, as the wollen ftuffs are ani- mal {ubftances as well as the porcupine quills, and. therefore eafily fufceptible of any. dye. The direCtors.of the Hudfon’s-bay Company will,. we hope,. order. their fervants at. the fettlements to- -eXamine carefully and minutely, the method em= ployed by the Indians in: dying: red. with. this: root, and to fend an account thereof, and greater quan- tities of this. root over, that feveral. chemifts may. be enabled to make experiments at large with them 5. for often, in dying, the experiments will not. fucceed,. when tried: in fall. quantities, : The wild inhabitants. of North. ee ee are Cer. tainly pofleffed of many. important arts;. which, when shospug bly, known,. would: enable the- Euro-. peans to. make a. better, and, more extenfive ufe of many. unnoticed plants, and productions of this | vaft. continent, both. in- phyfic,, and in. improv— ing- our manufatures,. one erecting. new. branches. of commerce, ‘Fo give an inftance o this, Iwill only mention, that the Spaniards of Mexico. have but. lately learnt: ef the inhabitants ef. California, the art. of dying YL, LX. I. the- soe 8:3 ‘the depeeft and moft lafting black, that ever was yet Known. ‘They call the plant.they employ for that purpofe Cafcalote ; it isarboreous, with imal] leaves and yellow flowers; its growth is full flower than that of an oak; it is the leaft corrofive of all the ‘known fubftances employed in dying, and. ftrikes the deepeft black ; fo that, for inftance, it penetrates -a hat to fuch a degree, that the very rags of it are thoroughly black. The leaves of the Cafcalote are fimilar to thofe of the Hufiaoke, another plant like- ‘wife ufed for dying black with, but ef an inferior ‘quality. The latitude of California lets us hope, that the country near the Mifliflippi, or one of the ¥lorida’s, contains this Caicalote, the acquifition of which would be of infinite ufe in our manufacs UES. ies) | Were Natural Hiftory thus employed in applying the natural produStions for procuring the necefiaries, ‘or adding to the comforts and ornaments, of human Jife, it would for the future free this {cience from tthe vulgar opinion, that it is merely fpeculative, and incapable of being of the leaft utility in common life; a prejudice which gains more ground by the injudicious and unprofitable manner, now chiefly in vogue, in ftudying this branch of human knowledges and which might be removed, if powerful trading ‘companies wouldencourage the efforts of the naturalift, by enabling them to fearch the treafures of mature, in the various countries fubje& to the Britifh Crown, and connected with its fubjects by trade and com- merce Pardon, Sir, that I detain you fo long on @ point of which you are ‘fo well convinced, and which [59] which you have frequent opportunities to convince others of. Iam, with the trueft regard, Srr, Your moft obedient, humble feryant,, John Reinhold Forfter. Ia : VI, An [ 60. J Y VIM. An Account of a Suberated Denarius of the Pletorian Family, adorned with an Etrufcan Infcription on the Reverfe, sever before publifbed or explained. In a Letter toMathew Maty, M.D. Sec. RS, ue the Rev. John Swinton, B. D. FP. R.'S. Ciffos: Archivorum of the Uni- ver fity of Oxford, Member of the Aca- demy degli Apatifti at Florence, and of the ~ Etrufcan Academy of Cortona in Tufcany. Dear Sir, I. Read Feb, 27, HE pieceI have undertaken to con- nde fider here is a fubzrated (fee T'az.1. n.J.) denarius of the Pletorian family, which lately fell into-my hands. It exhibits on one fide a female head, repreienting the goddefs Libera, or Proferpina, ac- cording to M. (1) Havercamp, before which ftand the letters [%asj{vz, P COSINE, very ill preferved. On the reverfe, we difcover a buft of the goddefs SORS, on a fort of bafis, adorned with the in{cription EF SOR ANT, or rather AN; under which, in the ex- ergue, appear the Etrufcan letters ¥) 7 AF] GUO), FIR, (1) Sig. Havercamp. Commentar, in Fam. Roman. Numifm Onn. Se. p. 313, 314. : 4 or Basie fe Philos Trans.Vol IXIL Tab. { 6t ] or-father FVR, ANTIE, 7. e. FORS, FORTVNA, er SORS, ANTU, or. ANTIAT, equivalent to the, Latin infcription above it. ‘The Etrufcan elements feem rather better preferved than the Latin. The coin is, however, in but indifferent -confervation, though pretty much of the thin filver plate remains Hill upon it. . | muft_not omit obferving, that it has never yet been communicated to the learned world. apy ‘The fymbol on the reverfe here is ‘the fame that occurs on the reverfes of two or three (2) other con- fular coins of the Pletorian family, with the word SORS attending it. The Latin in{fcription, on the piece before me, is extremely fimilar to one upon a denarius of the Ruftian family, now in. my fmali colleGtion, a draught of which may be feen in the plate (3) here referred to. ‘The fymbol there is a double Fortune, or rather two galeated Fortunes, _ which were confidered as deities by the Romans. _ The divinity SORS, on the coins of the Pletorian fa- mily, fimilar to mine, 4s afferted by (4) Vaillant and Hiavercamp to be the SORS, or rather one of the SORTES, worfhiped in the temple of the SORTES at Prenefte; whereas it was the SORS, or rather one of the SORTES, adored in the temple of thofe - deities at Antium, as we find demonitratively proved by the coin I am attempting to explain. The whole (2) Sig. Haverc. in Fam. Pletor. Tab. I. mn. 1, 2, 3. (3) ‘See Taz. Inte sonatas (4) 1. Vaill. Num. Antiqu. Familiar. Romanar. p. 2.38, 239, 240. Amiteledami, 1703. Sig. Haverc. Gomment. Fo. p. 324. fupet- [ 62] - faperftru€ture, therefore, ereéted by thofe two learned men on that fuppofition muft neceffarily fall to the ground, res 3 HY. The Etrufcan infcription, on the reverfe of my de~ narius, in the exergue, feems to allude to a paflage in’ Tully, relative to the origin of thofe deities denomi- nated sorTES by the Romans, and to be illuftrated by;.as well as to throw fome light upon, that famous paffage.. As this point is extremely curious, I halk beg leave to tran{cribe the whole paflage, which has been. handed down to us (5) in the following terms: <*« Numerium. Suffucium Preneftinorum monumenta «« declarant, honeftum hominem ac nobilem, fomniis. s« crebris, ad extremum etiam minacibus, cum jubere- “tur certo in: loco, filicem cedere, perterritum. vifis,. ‘‘ irridentibus fuis civibus, id agere coepiffe: itaque- ~ “« perfracto faxo.Sortes erupifle, in robore INSCVLPTIS, ‘“ PRISCARUM LITERARUM NoTIS. Is. eft hodie *< locus feptus.religiofe propter Jovis pueri,. qui lactens. «© cum Junone, Fortune in gremio fedens, mammam, «¢ adpetens,. &cc.” ** In fome of the antient monu- «¢ ments of Pranefte,, mention. is made of one Nu=. «« merius Suffucius. This man, who was one of the: -¢ moft confiderable and moft venerable: perfons in. « his city, both. for his probity and:noble extraction,, « was admonithed, in. different dreams, and at: laft. ‘« with terrible menaces, to go to a certain place in. * Prenefte, and. there cut a, flint. Being terrified: (5) Cic. De Divinat. Lib. Iie, hy és with: - [ 63 ] «¢ with thefe frequent vifions, he obeyed.. He ‘came *¢ to the place appointed, and there, in the prefence «¢ of feveral of his fellow-citizens, who laughed at-his «‘ attempt, tried to cut a flint ; which, to the great ‘* furprize of the fpectators, gave way to the edge of «the knife. And out of the body of the flint drop- «< ped feveral pieces of wood, (or rather oak) each of ‘¢which had an infcription IN THE ANTIENT “ CHARACTERS. ‘The place where this prodigy was “« performed is now walled in, becaufe in it is very “ religioufly kept an image of Fortune, holding Ja- « piter and Juno, reprefented as infants, in her arms, « &c.” As lhave formerly (6) proved that THE ANTE ENT CHARACTERS oF ITALY, or the PRISCARUM LITERARUM NoT @ of the Romans, were the Etruf. can letters; and as the infcription formed of thofe charaéters, mentioned by Tully, in the pafiage here pro- duced, cannot well be fuppofed (7) to have contained any other word than q\0> FIR, or rather IVR, applicable to the deity, or deities, fo called, and worfhiped, both at Antium and Prenefte; we may fairly {uppofe the Etrufcan infcription before me to have glanced at the celebrated paflage juft pro- (6) De -Prifcis Romanorum Literis Diffrtat. Oxonii 14746. Piilofoph. Tranfacd. Vol. LX}. p. 88, 8a. (7) This muft be allowed extremely probable, as the pre- tended origin of the ZoTs, mentioned by Tully, muft have been fuppofed prior to the foundation df their temp'es at Antinum and Prenefte, and therefore the original infcription was only, in all prdbability, fuppofed to have been either Fir, or FVR; - though, after the ere€&tion of thofe temples, the deity or deities, now ‘in view, might have been denominated F SOR ANT, and FOR ANT, on antient Roman coins, Vid. J. Vaill. & Sig. Haverc. in Fam, Pletor. et Ru/t. duced, | [ 64 J duced, and eonfequently that this paflage and my explication of that infcription may be prefumed mu- tually to fupport and illuftrate each other, IV. The firft. of the Etrufcan elements, on the reverfe- of my. coin, 9), is apparently that letter in the Etrufcan ~ alphabet which, in power, is equivalent (3) to F,. or PH, though the character here differs fomewhat from. -all the forms of that element that have hitherto oc- curred. to: me on the Etrufean monuments. The fecond is either I, or,as F am more inclined to believe, VY. That it ought rather to be confidered as V, feems. to me to appear from the obliquity of its pofition, in — refpect of the firft letter ;. which feems to indicate the- fide of the V next to that letter to have been effaced,. by the injuries of time. The third is undoubtedly. the antient Fufcan q, (9) or R, fomewhat blotted, or. blurred. The fourth and fifth manifeftly form the monogram NA, or AN, which has not yet occurred: tome on any other Etrufcan* monument. The fixth,. feventh, and eighth, Y } }, are evidently. equivalent: (8) Anton. Francife. Gor. Muf. Etrufce Vol. Ib p. 416, 4172. Florentia, 1737.. (g) Id. ibid. p. 412, 41. * From this inftance, as well as others, that might eafily be- produced, it appears, that the Etrufcans fometimes made ufe of - monograms, as well as the Greeks, Romans, and Phoenicians. . As the Romans, therefore,. feem to have ufed monograms before the commencement of any intercourfe with the Greeks, as is rendered probable by the very antient inedited quinarius here re-. . ferred to (fee Tas.. II. n..3.), which was, asI conceive, ftruck: . before the clofe of the fifth century of Rome; I am inclined to. believe, that they borrowed this manner of writing from the _Etrufcans, (10) to 3 [ 65 J (10) to the Latin, or Roman, letters TIE.’ The whole infcription is therefore YJ} P-€3 9 | §, FIR, or rather FVR, ANTIE, SORS, FORS, or FORTUNA, ANTII, altogether equipollent to the Latin infcription above it. That FVR ANTIE, in the antient Etrufcan language, ought to be rendered, in Latin, FORS, SORS, or FORT VNA, ANTIL, is apparent, from one of the Tables of Gubbio ; which, according to (11) Sig. Olivieri, exhibits the words AGRE TLATIE, equivalent to AGRI LATII, and is dire€tly in point. Hence we may conclude, that FIR, or rather FVR, anfwers to the FORS, or FORTVNA, of the Latins, the Etrufcans ufing conftantly V for O; and confequently that “5, PVR, PHVR, or FVR, in (12) Hebrew, or, as fome will have it, inthe (13) antient Perfic, FIR, or FVR, in Etrufcan, and FORS, or FORTVNA, in Latin, denoted the very fame thing. — V. That SORS, or SORTES, and FORTVNA, probably the fame deity, (14) were worfhiped both (10) Anton. Francifc. Gor. ubi fup. p. 407, 409, 414, 417 (11) Una Lettera del Signor Annibale degli Abati Olivieri, &c. Al Signor Abate Barthelemy, &c. p. 42. In Pefaro, 1757. (12) Efth. III. 7. (13) Val. Schiad, Lex Pentaglot. p. 1432. Hanovie, 1612. (14) Hence we find the celebrated temple of the Lots, or Sorves, at Prenefte to have been alfo denominated the temple of FORTUNE; nor do I doubt but the famous temple of the LOTS or SORTES, at Antium went likewife under that denomina- tion. Sig. Havercamp, ubi fup. p. 324, 325. Vor. LXII, K by by the Romans and the Etrufcans, will (1 5) not ad- mit of a doubt. ‘The Romans feem to have ufed the words SORS and FORTUNA for one deity, on fome occafions; and, on others, the term SORTES, as applicable to more divinities, and FORTWVNAE, or FORTUNAE ANTIAT, as relative totwo, to whom . they afligned the(16) epithets FORTIS, and FELIX. One or both of thofe epithets may poffibly be point- ed out to us by the letter F, which precedes the words SOR ANT, on the bafis below the butt of the goddefs SORS, on the reverfe of the coin in queftion. But that this is the true import of the word to which that letter belongs, I muft by no means take upon me pofitively to affirm. VI. The medals of the Pletorian family fimilar to that 1 have been confidering Havercamp (17) takes to have been ftruck in the time of the civil war, that fucceeded Julius Czefar’s death; in which, perhaps, he may not be very remote from truth, though this he has not irrefragably proved. If it fhould, how- ever, be allowed probable by the learned, the coin before me, which muft be nearly of the fame date with that war, will feem to have preceded about forty years the birth of Curist. (15) Vid. Anton. Francife. Gor. ubi fup. p. 214, 215. Sam. Pitife. in Lex. Antiquitat. Romanar. pail. aliofque author. quam lurim. : (16) Fabrett. Znfeript. Antiqu. cap. ix..p. 632. Sig. Haverc. ubi fup. p. 324, 369. Amfteledami, 1734, Vid. etiam Vulp. Ket. Lat. Profan. tom. Il. cap. v. p. 98, & feqq. ; (17) Sig. Haverc. ubi fup. p. 325. Se) VIL. [ 67 ] VIL. Who P. Cofinius, whofe name feems to have been handed down to us by the Denarius I have been at- tempting here to explain, was, or what was the par- ticular mode of his connetion with M. Pletorius, by whom the piece was ftruck, Icannot at prefent, for want of fufficient light from antient hiftory, and authentic Roman monuments, take upon me to decide. But this I may be allowed to fay, that the piece before me is the only coin of the Cofinian family that has hitherto efcaped the ravages of time. That the Cofinian family was of fome note in. Rome, Wwe may infer, not only from the very curious dena- rius that is the object of my attention here, but like- wife from two or three antient (18) Roman inf{crip- tions, which have preferved to us the name of that family. As for M. Pletorius, mentioned on the denarius before me, (19) and other fimilar coins, he was, according to M. Havercamp, (20) queftor to Brutus, one of Cefar’s murderers; and the piece I am endeavouring to explain firft appeared, as already obferved, a little (21) after that emperor’s death. The Etrufcan letters were not then intirely out of ufe: nay, they were not totally difufed in fome parts of Italy, and particularly at (22) Falerii, a confiderable (18) Jan. Gruter. Corp. tei ex recenf. Fo. Georg. Grav. p. CMLXXI. 9, DCLVIII. 1. Amfteladami, 1707. Ludovic. Ahtoay Murator. Nov. ria Vet. Infeript. p- DCCXCIV. 7. Mediolani, 1740. (19) Vid. I. Vaill. & Sig. Haverc. in Fam, Pletor. (20) Sic, Haverc. ubi fup. p. 325. (21) Id, Ibid. (22) Strab. Geogr. Lib. v. K 2 nutber [ 68 ] number of years after that tragical event. This we Jearn from Strabo, who flourifhed when Tiberius fat upon the imperial throne. VIII. Having now finifhed my attempt to elucidate a very curious inedited Etrufcan coin, highly meriting the attention of the learned; I would flatter myfelf, that an acquifition is hereby made to the fcience of antient medals, and confequently that this paper may prove not altogether unacceptable to the Royal Society. You will therefore be pleafed to lay it be- fore that very learned and moft illuftrious body ; and believe me to be, with all poffible confideration and efteem, SIR; Your much obliged, and very affectionate, humble Servant, Chrift-Church, Oxon. 3 Oa. 10, 1771s John Swinton. IX. 4 ae { 69 J IX. 4 Deduétion of the Quantity of the Suns Parallax from the Comparifon of the several O¢fervations of the late Tranfit of Venus, made in Europe, with thofe made an George Ifland zz she South Seas: — Communicated by Mr. Euler, jun. Secre- tary of the Imperial Academy of Peterf- burg; iz @ Letter to Charles Morton, M. D. Sec. R. S. and Acad. Imper, Pe- troburg, & ec. Soc. Read March 5, BSERVATIONES noviffimi tran ss J itus Veneris ante difcum Solis,, A. 1769, in infula maris Auftralis, King George: Ifland dicta inftitutas, calculo nuper fubjecit acade- micus nofter D. Lexell, earumque comparationem cum obfervationibus celebratiffimi hujus phznomeni. in Europa faétis inftituit, ut quantitatem parallaxis. Solaris erueret. Longum omnino foret, fi omnium, calculorum ab ipfo inftitutorum juftam heic adferre- vellemus expofitionem, idemque etiam minus ne- ceflarium, quum differtatio ejus hac de re confcripta,. ‘Tomo XVL noftrorum Commentariorum inferenda: fit; fumma igitur tantum eapita conclufionum in- ventarum perftringere fuffecerit. In anteceflum vero. e re eft monuiffe, methodum ab ipfo adhibitam. eandem efle, quam Uluftr. Eulerus invenit et que in parts. Lye | part. I. Tom. XIV. nov. Comment. fufe explicata fut, Siquidem obfervationes conta€tuum © externorum fuper infula King George inftitute, cum momentis pro contactibus internis allatis, non fatis bene con- fentire videantur, auctor nofter duos cafus feparatim fibi confiderandos efle ratus eft, priorem quo ratio habetur tam contactuum externorum, quam inter- norum, alterum vero, quo contactus tantum interni adhibentur. Combinatione autem facta obfervati- onum infule King George cum iis in Europa infti- tutis, pro priori cafu inventa eft parallaxis Solis hori- zontalis w—-8,68—o,0077 y, pro pofteriori r=8, 58 —o0,0080 y; ubinotandum eft y fignificare correéti- onem latitudinis geocentric Veneris pro aflumto tem- pore conjunctionis. Dum fimili ratione obfervationes ‘in Fortalitio Principis Wallie ad Sinum Hudfonis fate, cum Europeis comparantur, habetur pro priori cafu 7=8,82—0,e019 y et pro pofteriori z= 8,74—0,0022 y. Obfervationes denique Californi- enfes, cum Europeis comparate prebent 78,61 —o,0062 y. — Ut inter has conclufiones medium quoddam ad veritatem proxime accedens eligi poflet, notandam ommnino fuit, fingulis earum eo majorem certitudinis gradum tribui debere, quanto mmajores fuerint coefhicientes, quibus litera z in illis aequationibus affecta deprehenditur, ex quibus valores fupra allati hujus quantitatis elicitt funt; quo major enim hujufmodi coefficiens fuerit, eo fane minorem influxum errores in obfervando commifli habebunt, - ad verum valorem Parallaxis immutandum. Proba- bilitates igitur conclufionum ex fingulis obfervationi- bus Americanis deductarum hoc modo eftimando, : inventum [ave] inventum eft, eas refpeétive habendas effe proportio- nales numeris 11, 8, et 4. Porro ut obfervationes majori fide dignz ab incertioribus fecerni poffent, auctor nofter tres ftatuit hypothefes; 1. qua modo fupra dito medium fumitur ex conclufionibus que inveniuntur, dum omnes fine difcrimine obfervationes in ufum vocantur et pro qua habetur 7—8,63— ©,0063 y; 2. qua pro infula Regis Georgii mo- menta folum contactuum internorum in computum ducuntur, unde deducitur r=8,57—0,0057 y, et 3. denique qua obiervationes contactuum externorum ad Sinum Hudfonis facte excluduntur, que pre- bet «== 8,62 —0,0065 y. Quum tamen nulla fufficiens adefle videatur ratio cur momenta con- tactuum externorum ad Sinum Hud{onis pro dubiis haberi deberent, medio quafi fumto, inter media ex binis pofterioribus hypothefibus dedudta parallaxis tuto ftatui pofle videtur 7—=8,60—0,006 y. Ad hujus conclufionis ulteriorem verificationem, fingule obfervationes Americane comparate fuerunt cum lis in Lapponia faCtis, ubi tam ingreffum quam egref- fam Veneris obfervare licuit, fiquidem pro huju(modi _ obfervationibus, errores qui ex longitudinibus locorum perperam eftimatis in parallaxin redundant fere nuliius funt momenti. Tum autem mediis uti fupra dictum eft captis, inventi funt pro fingulis tribus hy- pothefibus fequentes valores ipfius wr: , I. 7=8,68—0,0076 y. 2, 7=8,67—0,0074 ys 3: 7=8,62—0,0077 y. He autem conclufiones a {upra inventis non magis difcrepant, quam ut diver- fitatis ratio ex leviufculis obfervationum erroribus facile reddi queat. Ex fingulis denique obfervationi- bus Americanis inter fe collatis fequentes eliciti fant valores [72 ] valores ipfius #; ex conta&tibus externis ad Sinum Hudfonis et fuper infula King George 7=0,16— 0,011 y3; ex contactibus internis in iifdem locis 7 == 8,47 -—- 0,011 y; ex contactibus internis ad Sinum Hudfonis et Californie —=8,46—o,0096 y; ex contactibus denique internis Californie et fuper Regis Georgii infula 7==8,48—o,0012 y. Quod conclufionem ex contactibus externis deduc- tam attinet, facile quidem liquet, eam plus jufto a veri- tate aberrare; quod vero determinationes ex conta¢tibus internis derivate, quafi in alteram partem peccent par- allaxin fupra inventa aliquanto minorem exhibentes, ex erroribus obfervationum facile admittendis provenire potuit. Ad valorem abfolutum ipfius ¢ aflignandum, quum jam requiratur, ut vera magnitudo correctionis y innotefcat, ea follicite quoque determinanda fuit ; momenta autem contactuum internorum in eo con- fentire videntur, quod hec correétio circiter 8” ftatut debeat, pofita femidiametro Solis 946,’"38, que me-: dia eft, inter femidiametri valorem a Cel. dela Lande affumptum, et quem aftronomi Angli adhibere folent. Hoc autem valore pro y adhibito, erit par- allaxis w==8,55 fec. femidiameter autem Veneris —= 28,6 fec. que ultima determinatio ultra 2 aut 3 partes decimas unius fecundi erronea effe nequit, obfervationibus micrometro objectivo captis eam egregie confirmantibus. Si corre¢tio latitudinis all- quanto effet minor, quod ex obfervationibus micro- metricis redditur probabile, quum tamen infra 5’ certe deprimi nequeat, parallaxis inde ultra partem guinquagefimam fecundi non reddetur dubia. Elementa i973) ) Elementa autem aftronomica ex valore parallaxis deducta jam ita fe habebunt : conjunctio vera Solts et Veneris geocentrica | contigit 1769 d. 3 Jun. zo. 2’ 32’ ‘Femp. medic fs Grenovicenk feu 10 4) 45 © Temp, vera: Pro quo momento erat, : sina 1. Longitudo Solis et Veneris 2 13 27 20 2. Latitudo geoc. Veneris zo 18,8Bor, 3. Parallaxis Solis horizontalis 3,55 Hine facile elicitar longitudinem geographicam loci fuper infula King George, ubi obfervatio peracta fuit, a meridiano Grenovicenfi ftatui debere 9* 50’ 6ft:: Quum pro imfula Recs Georgit ea contactuum momenta, in calculo adhibita fuerint, que a Cel. Green aflignata deprehenduntur, excepto momente contactus interni pro ingreflu, ubi momentum a Cel. Dod. Solander notatum, in ufum fuit vocatum, merito difpiciendum erat, quam fubeat parallaxis mutationem, fi alia contactuum momenta pro hoc loco notata adhibita fuiffent. Quod igitur contactus internos attinet, duas fupponere licuit hypothefes bina quafi extrema in fe continentes, priorem qua obfer- vatio contactus interni pro ingreflu a Cel. Green facta cum.-ea contactus interni pro egreflu a Cl. Cook inftituta combinatur, Boers qua mutata vice obfervatio prioris contaus interni a D®? Cook fa&a combinatur cum momento pofterioris conta@us in- terni a Cel. Green affignato. Prior hypothefis dat parallaxin 7=8,48—o,0080 y, pofterior vero w= 3,65—0,0080 y, ubi medium z= 8,57—0, o08oy VoL. LXII. L VIX [ ee vix differt a determinatione ante adhibita. De mie< mentis contactuum externorum generatim quidem liquet, ea cum obfervationibus internorum Ueneacan conciliari poffe, queniam mora inter utriufque generis contactus vera multo minor obfervata fit; quo certius tamen conftaret precipuam aberrationis caufam in contactibus externis efle querendam, fequenti modo in exaCtitudinem momentorum tam contactibus ex- ternis quam internis refpondentium, auctori noftro inquirere vifum eft. Momenta contactuum inter- norum, cum oblervatione ejufdem contactus pro in- ereflu Grenovici a Celeb. Mafkelyne facta comparat, indeque deducit aflumtam longitudinem pro King George Ifland 22’ vet 25” efie augendam: hee deinde momenta fimiliter comparando cum obferva- tione contactus interni pro egreflu in Gurjef a Cel. Lowits inftituta, invenit eandem longitudinem 25 vel 20” effe augendam, ex quo quum hec correttio per quatuor diverfi generis comparationes fere eadem prodeat, concludendi rationem habere fibi vifus eft, in contactibus internis graves errores latere nequaquam probabile effle. Dum pro contactibus externis fimile inftituendum fuit examen, ne videretar parallaxin nimis parvam fuppofuiffe, ftudio maximam elegit que x his contactibus deduci poteft, {cilicet 7 =9,04— 0,007 3 i unde deducit correctionem longitudinis geographice pro King George Ifland ad 32!” affur- gere. Poftmodum facta combinatione binorum con- tactuum externorum, cum obfervatione contaétus interni pro egreflu in Wardhus a Rev. Pat. Hell in- {tituta, invenit correétionem longitudinis per unam comparationem prodire 4g fec. per alteram vero 16, que infignis difcrepantia certe non nili ab a ne Pos.) dine contactuum externorum pro infula King George oriri poteft, fiquidem longitudo Wardhufi vix ultra 5” effe poffit dubia. ~ Quoniam plurimis aftronomis placuit parallaxin _ multo majorem adhibere, quam que nune inventa fuit, opere etiam pretium erat difquirere, quoufque errores obfervationum pro contaétibus internis per- tingere debeant, fi parallaxis {upponatur vel g vel 1o fecundorum. Inventum autem fuit pro paral- laxi 9’’, fi bini contactus interni pro Infula Regis Georgii, cum ejufdem nominis Europeis conferan- tur, fummam errorum ad 40 fere fecunda increfcere, pro parallaxi autem ro fec, eam duobus minutis pri- mis minorem fupponi non poffe, quorum ut pofterius abfurdum, ita prius quoque valde improbabile vi- detur. Deinde expendendum quoque fuit, utrum ex ob- fervationibus diftantiarum minimarum, certi quic~ quam de parallaxi Solis concludi poffit. Si autem — comparatio inftituatur diftantie minime pro Infula King George inventz cum diftantis ad finum Hudfonis, Noritoni in Penfylvania, et Nove Angliz a Cl. Win- aa menfuratis, inveniuntur pro parallaxi hi valores == FO" 7,5/9,. Velig 2a0)',90,| Vel i= 9,97 Guo- rum diffenfus jam certiffimo eft indicio quam parum fidei hujufmodi obfervationibus tribui debeat, in quaitione hujus generis decidenda. Ceterum f foe erint, qui ex his menfuris parallaxin g/’ vel etiam 10 fec. deducere velint, ab illis fequentis dubil plenam folationem merito expettamus: qui fiat, ut potius fupponi debeat, fingulis obfervationibus contactuum internorum a tot obfervatoribus inftitutis, ad mini- mum errores 20 fec. vel 30 fec. inefle, quam binas Li 2 vel [76] +el tres menfuras diftantiarum minimaram micros metro captas 2 aut 3 fecundorum erroribus obnoxias effle? Denique et auctori noftro placuit quedam ad- jicere de effeCtu atmofpharz Veneris ad durationem tranfitus immunuendam; obfervavit autem hanc quef- - tionem in dubio relinquendam effe, donee exactiflime determinare licuerit, tam latitudinem geocentricam Yeneris, feu diftantiam minimam veram, quam ac- curatam menfuram diametri Solis. Preterea reticendum quoque non eft, eundem }). Lexell obfervationes fuper diftantias marginum Solis et Veneris minimas, Noritoni inftitutas, quas Mluftr. Societas Scientiarum nobifcum communicavit,- ealculo fubjecifie, et ex pulcherrimo confenfu fingula- rum fere obfervationum, conclufiffe hanc diftantiam minimam fore fo’ 10” pofita femt-diametro Solis 947" » feu etiam 10’ 9” pofita femi-diametro Solis 945’,5 uti celeb. Mafkelyne eam affignare folet. Exiftimat autem idem D. Lexell utra smque diftantie minime quantitatem uno fecundo augeri poffe, quia probabilius videtur diftantias marginum jufto ma- fores efle captas, quam quod in defectu peccaverint. Lista ee sy oo 3 ea ees ey Sas ass : en ee Beene Dalen ait SRAIST ARNT an ie iaieaias S eee 3 Lhiles Trans Vol IXH TaN, - ——— Sm : = : : — : = =o as = i v z m) : : mail Al ; % ; e ; ‘€ / I S : : 3 ss \ i H | ie a a | j : / 7 A = se é Wy ee = en s Oe et ; PART Low hand toward of Judie, Ry ee Sst Su ae RN mee if j < - i f F “fr , - < i eas f Vifurkiiver Here the Ganges went we anit Anchored Anno, 1907. x ik A = fae of the =a ae a Tak : igs fe if : } “ Stee Latitude of Tdilid pa. 21 « 28LV. lee Siew A ie E DPD 2 é Na ] Longitude De ., 89.26.46 tt by Jupiters Satdlites =f a : : qs Vartiowgf ¢ the. Conypafe TT, OZ Y. ; A pee . ye ‘ 3 ‘ ~ Judda é | ee Be . | Hi Hi Heel We a | ; ‘4 \ | | q =| so ] 2 - Eel é |e i Maca VS: € o ¥ | Ei20 Wee 5 AS ij me t i 72! Z = = “lis : ‘ IN . Se ? 3 Se By a ij i ; } : RC 19 24 46 . eee es i asap z 4 1g y 14-19 24.0 ‘ - 25 se : Sand & Breakers 3 b “Ft > oe = ease uy Mont de Latiay Ze ca } aa | ti oP aa ‘ Moan elite domes Zaye > = L ahayw Baye dutrtigeis GEEK 5g =I ae - ! y 5 Me hy he de 35/ 38 40 Loint a, we Arqutho Ene. Me Vi / te Ze y = Ful 4 Mor | Z . j Cap delesrial as oy 2 : aanabel ~ oe ‘ 7 mast OT DL dinrg SO m9 Eb 7 %, Hodeyda ‘ r . ey \\ | L Stirrbyyy 4 i Vf t * f a ) \ ii en ‘ 5 hos 256 ait a Ty as ae . Nest pare et : ae rag S |} ee 5 a ae ee : 2 4 22 lt CapVund ~ oe = & |] Pak pe . Mosque tha lips Namel S Bile & | : ‘i 3 |]. : fi { a Meouchitr Be Eye z v\ ~ i” = 0 25 4 ot pe eo i ies zs . | a eRe oe SIRES a a ~I- - - areas ni Cee Note. the Abyfriuan Shore, ww laid down wr this Chart 26 07°30 ; Of : Miles to f ‘ar bo the Westward . - s s - * xe at —_ —— 3 ras ss eee ao -- — — i 7 ' \' fs i ea - ‘ = Wy z 3 aa (OG, i ce \ Neeson t : ~ a i = )) \ , c hh), z , ~ ra oe ! ' ee aad & : ie reg - —— = : PRET: oo : y = «Buin lee = 3 a a STITT ER a 7 y oy ee es oo CQ SUG TYAN SA iy Fs ia) Pe ire Vim parest’ dl f pay iM a y IMT 2 \ enn Sill emery oa ES } } { —— 4 ty ‘ vy ) lhe Harbour and Road of SUDDA . rT Set anh cccagnaeneneenen™ eae : Ea ) anes hee he prec ee Geta ae fen, Pr Store eee eer” ey 7 +4, ¢ Chae tay Philow Trans Vol IMM Tab IV pegs. Vo es ev aes Pea py5 a a e456 Coe MOCHA ROAD Be: / cale c* 2 relish Mceles. 1 Scal. of hig A Miles D a J eer SS EEL Z 7 A. Lhe. Northern [of the Road . SBE Lhe Bridge. for Landing C. The highest Mok : D. Awd Castle on arTslinl V makes vy Southern piof the Bay. | oii! he Anchoring: Julace : I t | Ct el a fea TT . ee eegnetteer ere eenarcserer® (997 X. A Letter to the Rev. Mr. Matkelyne, Aftronomer Royal, F. RS. accompany- ing a new Chart of the Red Sea, with two Draughts of the Roads of Mocha and Judda, and feveral Obfervations made during a Voyage on that Sea, by Capt. Charles Newland. | Sl sR, Read March 12, Ff Beg leave to lay before you a chart ye of the Red Sea, conftru@ed from | materials that 1 became poffeffed of, during my refi- dence in the Eaft Indias; which chart, upon my ‘voyage to Mocha and Judda, I experienced to be the beft I have ever feen. ‘The only material error that I ever difcovered in it, is, that the Abyffinian fhore oppofite Mocha is placed too far to the weft- ward by 25 or 30 miles, and that there are feveral {mall iflands upon the fame fhore, not taken notice of in any other chart; which iflands I have marked _ inthe chart I now fend you (See T’ab. III.) toge- ther with two draughts of the roads of Mocha and Judda (Tab. IV.), which, if you think will be Of any utility, are entirely at your fervice. Tam, SIR, With the utmoft refpect, your moft obedient humble fervant, Cha’, Newland. Longitude | [ 78 ] | Longitude of Judda by 12 Diftances of the » from © « - Work’d by the Britifh Mariner’s Guide 39 53 45 And by the Ephemeris for 1769 40 1 7 Difference 7 Be / Mt By Jupiter’s Satellites ° 2. . . 39 26 4 yD GAG Oe Pe es a 34 22 Soy XI. Remarks [oe 4 XI. Remarks and Obfervations made on board the Ship Kellall, on a Voyage to _ Judda and Mocha, iw 1769, dy the Same. Read March 12, FF N my run from Socatra to Cape piles Aden, I made the dift. 8° 20’ W. and from Cochin 29° 39 W. ‘The latitude of the above Cape is laid down in moft books and charts in 13° N. which I find is about 15 miles too much to the northward, according to the obfervation I took on the 1oth of February 1769, as well as three other very good obfervers: by the medium of the whole we made the latitude 12° 41’ N. the Cape then bore N. N. W. 4 W.dift. 5 miles which gives near 4’ of latitude ; ‘that, added to 12° 41’ -N. gives 12° 45’ N. for the latitude of the fouthernmoft point of the Cape. This cape, or headland, is one of the moft re- markable I ever faw, when coming from the eait- ward ; it is fo very high and rugged, that it may be feen, I believe, 15 leagues at leaft, in fine weather. The tops of thofe ragged rocks refemble fo many chimneys and fpires; and, as you approach the cape, you fee a zigzag wall, or whitith pathway, cut through the racks, not at a very great diftance from the waterfide; a little below this, at the S. E. end, [be] | end, you will fee fomething that looks very like two mofques; but this cannot be feen at a greater diftance than 4 or 5 leagues; but when it is, you may be certain it is Cape Aden, and may then fteer your courfe for Babelmandel accordingly. A little to the weftward of this cape, there is an- other hich craggy headland, equally high and craggy as that of Aden, between which two there is an opening, very much refembling a {mall narrow ftreight, but in reality itis only a deep bay, the bot- tom of which is very low land, fo low, that it can- not be feen from the maft-head, except you are clofe in fhore: by this deception, people have mif- taken it for the Streight of Babelmandel, and have been fo far embayed, before they perceived their miftake, that it was with the greateft difficulty they got out again. On Bee fide of this bay lies a large rock, jutt at the entrance, and at about a quarter of a mile from the fhore: when thefe are feen, you may be fare it is not the Streight of Babelmandel.- Was a fhip to fall in with this place, and had not had an obfervation for forme days before, I think it would be very eafy to miftake one for the other; there is only this dif ference, that Cape Aden is high and rugged, and Babelmandel is rather low and {mooth, and the ifland (as the Dueory obferves) makes like a gunners coin. The beft courfe to fteer fram Cape Aden to Saint Antony is W. by S. by the compafs, and that will carry you clear of the fhoal lying off that point. J amade the diftance between Cape Aden and Cape Saint Aathony, by the thip’s run, 17 leagues; the latter cape Philos Trans Vol, LXW. Tab V./-87. Gaza Ts «Baste dé «Bast 7Te. dt: { 8r J cape is high land, and may be feen in fair weather about 12 leagues. N. B. When Cape Aden bore N. N. W. = W. about 5 miles, I had 4o fathom, coarfe fand - and {mail fhells, the opening of the {mall bay _ appeared like the narrow eae of Bae . belmandel, N. We Thus fheweth Cape Aden C, when the opening A bears W.N. W. £N, diftance about 4 miles. Wap. Ve Tig, ¥: Thus fheweth “Cape Aden, when coming from the eaftward, at the diftance of about 7 leagues, and when it bears about W. by N. Fig. 2. ‘To give any directions for failing through the narrow Streight of Babelmandel, and from thence to Mocha road, would be needlefs, as they are fo __ extremely good in the Eaft India DireGtory, as dlfo for anchoring and failing into the road, with proper Hearings, and diftance to anchor from the town. Thus fheweth Cape Babelmandel, when it bears N. W. by W. diftance 6 or 7 leagues, Fig. 3. Thus fheweth Cape Aden, when it bears W. a ~ 10 or 11 leagues, Fig, 4, From Mocha towards Judda, the iflands of Jebbel- Zeker Aloric are pretty large, and may be feen in clear weather 7 or 8 leagues 5 ; they are fix in number, the fouthernmoft lies in the latitude of 13° 4.5’ N. and bears from Mocha N. W. by W. nearly, diftance Vor. LXII. M about [ 82 ] about 40 miles.. A little to the northward of thofe iflands lies Jebbel-Zeker, a very high large ifland, that may be feen in fair weather 12 or 13 leagues. Very near this ifland, of the N. E.. fide, Ke three fmall ones, not difcernible at a diftance of 4 leagues. The N. end of the large ifland Jebbel-Zeker lies in the latitude of 14° 10’ N. : In coafting along the Arabian fhore, abreaft of the. large ifland, care muft be taken not to come too- near the fhore, as there is a fhoal water, between the | mofque of Cape Name and Cape Namel, 7 or 8 miles from the fhore, and foul ground, with overfalls. The edge of this bank is very fteep too; for when I was. from the fhore about the above diftance, I had pre- Jently from 20 to 7 fathom water, and then 6 fathom.. I immediately hauled off, and deepened my water again very foon, to 13,°14, and then 20 fathoms, as may be feen by the foundings in the draught, Tab, IV. ‘The true courfe from Jebbel-Zeker to the Subu- gars is N. W. by N.; diftance 20 leagues. ‘“T’hofe iflands are extremely i) laid down in three different charts I have met with for the Red Sea; they trench: away about N. N. W. and S. 5S. E. and extend trom N. to S.: about 20 miles; they are nine. in number, and not. very high, however, I believe they may be feen, in clear weather, from the maft- head 7 or 8 leagues; the latitude of the S. and N.. ends 14) G7 tO Te 1s 0 N. E. of thofe iflands lies a low white ifland (which I call Sandy Ifland), environed all round with fhoal water; to the fouthward of which, the. fhoal feemed, from the maft-head, to extend. from the ifland 3 or 4 miles. I paffed it at about 6, miles. diftance, [ 83 ] diftance, and never had lefs than 26 fathom, fandy ground. ‘Two or 3 miles within me, appeared like very fhoal water. Its latitude is 15° 22’ N. About 40 miles N. N. E. from the Subugars, lies the Ifland Comoran, a very low blackifh ifland, trenching away N.W. and S.S.E. excepting the north end, which turns off fuddenly, and ftretches away N.N.E. When at the diftance of about 5 miles from this ifland, I had 2 3 fathom water, hard fand and gravel Rtones, at the fame time it bore E.N.E. and, when the body bore N. E. diftance about 6 miles, I faw a large {quare white houfe near the waterfide. N. W. by N. by the compafs, from the Subu- gars, lies the Ifland Jebbel- Tar, diftance about 25 miles. This ifland is of a moderate height, and may be feen 9 or 10 leagues from the maft-head, in clear weather ; its latitude is about 15° 36’ N. and when it bore W. about 10 miles, I had 33 fathom Water, a fandy bottom. After taking your departure from this ifland, hen bound to Judda, the beft courfe to fteer is N.N. W. 4 W. which is near the mid channel; by is doing, you may run boldly on all night, without ear. From Jebbel-Tar to the {mail iflands on the Ara- bian fide, laid down in about 18° N. latitude, I made. the courfe N. 22° 49’, W. diftance 159 miles. It was about fun-fet when I firft faw two of thofe iflands; they then bore from N.E. to S.E. by S. diftance from the neareft of them about 6 miles, and. breakers a little to the fouthward about 5 miles. The fouthernmoft of thefe iflands lies in the latitude of 18° 2’ N. according to my bearing and diftance at M 2 fun- fet ; [84] fun-fet; they are very low, but long, and ftretchs to the northward; I had no foundings, 80 fathom at | the above diftance. ‘di From the above iflands I faw no dangers, till I was in the latitude of 19° 24” N. (upon the Ethi- opian fhore), when I faw breakers; and a little to. the N. W. of them I faw a low fandy ifland, that. cannot polfibly be feen at a greater diftance than. 6 or 7 miles; at the fame time I {aw two highiflands. to the weft and northward of them, diftance 8 or 10 leagues. And, upon the eaftern or Arabian fhore, in the: latitude of 20° 14’ N. I faw a low {mall fandy ifland 3. and 3 or 4 miles farther to the northward, an- other low fandy ifland, about the fize of the former, neither of which can be feen, in clear weather, at a greater diftance than 3 leagues. At the fame time, a little to the northward and weftward withal, I faw. breakers very plain from the fhip’s deck; thofe iflands. were called (by the pilot I had on board) Marfaha- ram; he at the fame time informed me, that it was very dangerous to go to the eaftward of them, it being nothing but fhoals and rocks. When you are to the aorthward of thefe iflands and breakers, you will fee the high land of Goofs, at the diftance of 14 leagues, the approaching of which is very dangerous without: a pilot, as well as all the reft of the coaft quite to Judda, it being fo incumbered with rocks and fhoals 5 and what makes it the more hazardous is, there being. no foundings till you come atonce upon a hard fteep f{and-bank, oraledge of rocks; therefore, it willbe ab- folutely neceffary to take a pilot on board, in or about 20° N. latitude, if poffible; but fhould you not be fo: fortunate te Tra [35 7] fortunate as to get one before you come near Judda, it would be moft certainly prudent to keep 30 or 40 miles from the fhore, at leaft fo far that you can but juft difcern the high land of Goofs and Gedan, at which diftance there is no danger. Although this may appear a great diftance for the pilots to come off to the fhip, yet they will immediately do it as foon as they hear your gun, and not till then. It is indeed amazing, and almoft incredible to be told, how far thefe pilots will hear the guns on aftill morning or evening, which are theproper times for the guns to. be fired. Obferve to fire the firft as foon as you fee the fun appear in the horizon, and the fecond as foon as the lower limb is juft out of the water; in the evening, the firft as foon as the lower limb touches the water, and the fecond when the upper limb is below the horizon.. Four firingsin one day is all that are neceflary; but they are to be repeated every day till you get a pilot. They know pretty near the time the India fhips will arrive,.and go down to the water fide every night and morning, and juft as the fun is. rifing or fetting, they lay their ear clofe to the ground. for three or four minutes, and pretend to fay, that if a fhip is not more than two or two and a half degrees diftance when the gun is fired, they can. ~ either hear the report or find the ground fhake under them; upon which they take a boat and come off to pilot you-in.. This may feem a little extraordinary to- a perfon that never was there; but, however ftrange it may appear, I was affured by a gentleman of un- doubted veracity, that he run by the log g5 miles from the time of firing his two guns in the morning,. till he faw the pilot in the evening; and when he came [ 86 J i ‘came on board, he declared that he heard the two guns that morning at fun-rifing, upon the ftrength . of which, he took his boat and put of. . a To fail into Judda harbour, or rather road, without . a pilot, would be impoflible for a ftranger, there being fo many fand-banks and fhelves of rocks; but when. “you are in, itis one of the fafeft places that can_ peflibly be; you may make your fhip faft with any old junk, and there is no danger, though you are furrounded with nothing but rocks and fands. The beft bearing for anchoring is the great Mofque E. by S. and the extremes of the land from S. by E. | to N. N. W. diftance from the landing-place about two miles. vie Latitude of Judda 21 28° N. Longitude Ditto 39 26 45 E. Variation of the compafs hn pamROWS. I left Judda the 30th of July 1769, and paffed by the grap fhoals (lying in the latitude of 21° 20’ N.) at about a mile’s diftance, from which I took my departure and made my courfe the firft day S. 24° W. dift. 56 miles; the fecond day, S.15°E. dift. 100 miles. On the third day about 6 o'clock — in the afternoon I faw a very high land on the Ethi- opian fhore (about the latitude of 18° 38’ N.) and fome {mall iflands a little to the Northward of it; the high land bore about W. N. W. and the fmall iflands N. W. dift. from the high land about 10 leagues; we had then run from the Grab fhoal 195 miles. From ae From the fhip’s place at 6 P. M. run about 68 min. S. S. E. by the compafs, and then made a low long fandy ifland bearing 5. W. about 8 miles on the fame fhore, on the South end of which are breakers that may be feen 8 or g miles; the middle of this ifland Jies in or near the latitude of 16° 427 N. from thence to Jebbel-Tar the diftance is 128 miles, in a direct S. E. courfe by the compafs. Thus fheweth the ifland of Jebbel-Tar, when it bears W. by S. dift. about 10 miles;.Tab. V. fig. 5. From Jebbel-Tar to Jebbel-Zeker, the courfe is by the compas S. E. by S. diftance about 100 miles: the. paflage to the Weftward of it I had been informed was a very good one, but I find by experi-. ence it is not fo good as that to the Eaftward of it; nor do I think it fo fafe to go that paflage in the night, except you are clofe tothe ifland before it is dark, and well to the Southward of the large Jebbel-Zeker, fo that you can fee the Southernmoft of the {mall. Jebbel-Zeker Alories, as I found a very ftrong cur- rent fetting upon the Abyffinian fhore, and to the. Southward withal. On the evening of the 4th of. Auguft at. fun-fet,,the large Jebbel-Zeker bore KE... by S. diftance about 4 leagues, and the Southernmoft. one S..S. E.. half E.. Having a very fine wind, and. wanting to be at Mocha very much, I carried a mo- derate fail, and fteered from fun-fet till 8-o’clock South | about 7 miles, from 8 till 10 S.by E. 7 miles, from. to till 12 S.S.E. 7. miles, and then bore away, con- cluding myfelf well to the Southward of all the. lands of Jebbel-Zeker Alorie; and indeed had my. draught been gcod, and had I met with no current, J. faould have been clear of every. thing according to. my. [ 88 J my run, which gave me about ¢ miles to the South= ward of the Southernmoft Jebbel-Zeker; but to my . great furprize, juft as I was bearing away, Liaw two lands right a-head, within about half a mile of us. We were then going at therate of 4 knots: I imme- diately hauled off to the 5. W. and foon after S. till I thought we were quite clear, and then (about two o'clock) going to bear away a fecond time, we difcovered two very fmall iflands, lefs than a mile from us, right a-head, upon which I thortened fail, and laid the fhip’s head to the Weftward till day-light, when I perceived myfelf furrounded with a parcel of {mall iflands (not laid down in any chart), about half way between Jebbel-Zeker Alories and the Abyffinian fhore. It falling little wind, and the cur- rent driving me very faft upon the Abyffjnian fhore,: J let go my anchor in 27 fathom fandy bottom, and there laid till ro in the morning, when a breeze of wind fprung up from the Northward; I then im- mediately hove up my anchor, and ftood over for Mocha fteering N. 77° E. diftance 39 miles: when at anchor, I was about 3 miles from the Abyffinian fhore, and about half a mile froma large rock, or rather a {mall ifland. While I was among thefe iflands, I faw no breakers or fhoal water; the leaft water we had was 27 fathom, atid never more than 40 fathom, and moftly fandy ground. Moft of thefe {mall iflands I have marked in my chart, pretty near as they bear from each other; the diftance from the Abyffinian to the Arabian fhore is not more than 40 or 45 miles (about the latitude of 13° 25° N.) though in moft charts it is made to meafure from 70 to 80 miles, which certainly muft be a great deal / 2 [ 89 ] too much; for, fuppofing an error in my run from fhore to fhore 10 miles, it would only make the diftance 50 miles, which is 25 or 30 miles lefs than the charts give. | Latitude obferved at Mocha —_—_13° 23’ N. Variation of the compafs 12 539° OW. | Vor, LXI. N XII. Ae { ¥ ) XII. Mi eafy Method to di fil frelb Water from Salt W ater at ais 3 Y aie N ewland. ‘Read Misch 12, AHE materials He ey ns this ase procefs are the following; a cop- per or iron pot. of 1 5 or 20 gallons, an empty caik, iome fheet lead, a {mall jar,,a few wood-afhes or foap,-and billet-wood for fewel. See Tab. V. fig. 6. where A is the ftill or pot; B the pipe or worm; C the worm-tub; D the receiver; EE the fagong or fire-place; and f the ploaer: to put in water. First, In order to make my pipe or worm B, I took as much fheet lead as I thought was fuffi- cient for the purpofe, and beat’ it on a {ponge ftaff to make it round: this being done, I was fomewhat at a lofs for folder; however, I fupplied that defici- ency with good patte and dungerec (or thin canvas) _ laid well on, and over that, a fecond coat of pafte and dungerec, and then a covering of fmall cered line hove clofe together and very tight round, over which I put my third coat of pafte and dungerec, which I found, to my great fatisfa€tion, was fufficient to keep’ it from blowing. : The next thing was to fix my pipe B in the pot or {till head A. When I had well fecured the pot in the fagong EE. I filled it 3bout two thirds full of falt water (about 15 gallons), with which I mixt two’or three double handfulls of wood-ifhes, and ftirred it well together, in order to toften the falt water; I then fixt the lid (which was made i or 4 made of plank 3 inches thick) in which there are two holes, one for the end of the pipe, the other to put in water as occafion requires, without taking off the lid. It muft be well obferved, that the end of the pipe is net put more than 2 or 3 inches within the ftiil head ; for, fhouid it be put too far in, when the water boils, the bubbles or faline particles get into the end of the pipe, and make the water brackifh in the receiver D. To prevent the fteam from coming out at the plug-hole f or lid A, I. made a kind of mortar, ‘with wood-afhes, falt water, and rope cut very {mall and beat well together, and then applied it thereto, which anfwered my purpofe ex- tremely well. Now my pipe is fixt in the ftili-head, I fhall proceed in the next place to carry it through the worm tub C into the receiver D. My worm-tub is nothing more than an empty cafk with one of the heads taken out, and in each fide a round hole cut, of about 3 inches diameter, for the pipe B to pafs through into the receiver D, which is fixt at a little diftance from the tub C. ‘Tohe receiver has alfo a wooden lid like that of the ftill-head, with a hole in it for the end of the worm to go through into the re- ceiver D; care muft be taken, that no fteam comes out there, as well as at the ftill-head. An empty jac will anfwer the purpofe of a receiver very well. | _ Notwithftanding the pipe B paffes through the tub C of cold water, your jar will be very hot; I therefore thought it neceflary to keep a perfon continually wetting it with cold water, which not only kept the jar from breaking, but made the freth water cold and fit for ufe immediately after the ftill was N 2 taken [ 92 ] taken off. T he foregoing directions ftrictly obferved, a quantity of 8 or 10 gallons will be produced every: day, each day containing 12 hours, Note. Every five or fix hours you muft replenith the ftill with about five gallons of water, as 1 found. my firft ftock confumed about a gallon ee hour - boiling. XIII. Ob- [ 93 ] XI. Objervations on the milky Appearance of fome Spots of Water in fb Sea; by the Same. Read March 12, ¥ 'T’ has been remarked by feveral nayi- Se gators, on their paflage from Mocha to Bombay, Surat, &c. that they had difcovered in the night {pots of water as white as milk, and could never affign any reafon for it; and many, have been fo much alarmed, that they have immediately hove to and founded; but I never heard of any body ever getting ground. In my paflage acrofs thofe feas in the Kelfall, I difcovered all of a fudden, about 8 o'clock in the evening, the water all round me as white as milk (intermixt with ftreaks or ferpentine lines of black water). I immediately drew a bucket of it, and carried it to the light, where it appeared jut as other water ; I drew feveral more, and found it the fame: fome I kept till the next morning, when I could per- ceive no difference from that alongfide. We had run by the log go min. from the time we firft obferved it till daylight, and during all that time the water con- tinued white as milk, but at full daylight it was of its ufual colour. ‘The next evening about 7 o'clock the water appeared again as white as before; I then drew another bucket and carried it toa very dark place, and holding my head clofe to the bucket: could per- ceive, [ 94 ] | ceive, with my naked eye, an innumerable quantity of animalcules floating about alive, which enlight- ened that {mall body of water to an amazing degree. From thence I conclude that the whole mafs of water mutt be filled with this {mall fifth fpawn or animal- cules, and that this is without all doubt the reafon of the water’s appearing fo white in the night-time. We run by the log, from the time we firft faw it till the latter part of the fecond night (the time we loft fight of it) about 170 miles. N. B. Latitude about 15° 10’ N. and S. W. dift. from Cape Aden 12° 18’ E. On the 30th of Auguft 1769, at 3 o'clock in the morning, I faw a comet 8° 20’ from Aldebaran S. W. and the tail ftreaming to the Weftward. I made the meridian diftance from Cape Aden to | Striking Sounding on the Malabar coaft (in the lat. DE tate iva) on shrek XIV. L og-] XIV. A Letter rin Mr. Peter Dollond, zo Nevil Mafkelyne, F. R. S. and LA Ale mer Royal; defcribing fame Additions and Alterations made to Hadley’s Quadrant, to render it more Serviceable at Sea. Reverend Sir, Read March 29; HE particular attention, you have Baie TT always fhown to any improve- ment Deitie to the advantage of aftronomy or na- vigation, makes.me take the liberty to trouble you with an account of fome additions and alterations I have lately made to the Hadley’s quadrant. The general ufe of this inftrument at fea is fo well known, that no mention need be made of the im- portance of any improvements in the conftruction, that may render the obfervation more exact, and Saas more frequent apo sates of nekige them ‘The glaffes of the Hadley’ s quadrant fhould have Ane two furfaces perfect planes, and perfectly par- allel to each other. From feveral years practice in grinding thefe glaffes, I have found out methods of making them to great exactnefs; but the advantage, that fhould arife from the goodnefs of the glafles, has [ 96] has oftentimes been defeated by the index glafs being bent by the brafs frame that contains it: to prevent this, I have contrived the frame, fo that the glafs lies on three points, and the part that preffes againft the front of the glafs has alfo three points exa@ly — oppolite to the former. Thefe points are made to confine the glafs by three fcrews at the back,. that act exactly oppofite to the points between which the glafs is placed. ‘This little contrivance may be of fome ufe ; but the principal improvements are in the me- thods of adjufting the glaffes; particularly for the back obfervation. The method hitherto practifed for adjufting that part of the in{ftrument, by means of the oppofite horizons at fea, has been attended with fo many difficulties that it has fcarce ever been ufed; for fo little dependance could be made on the obfervations _ taken this way, that the beft Hadley’s fextants made for the purpofes of obferving the diftances of the Moon from the Sun or fixed ftars, have been always made without the horizon glafs for the back obfer- vation ; for want of which, many valuable obferva- tions of the Sun and Moon have been loft, when their diftance has exceeded 129 degrees. To make the adjuftment of the back obfervation eafy and exact, I have applied an index to the. back horizon glafs, by which it may be moved into 4 parallel pofition to the index glafs, in order to give it the two adjuftments, in the fame manner’as the fore horizon glafs is adjufted. ‘Then, by moving the index to which the back horizon glafs is fixed, exactly go degrees (which is known by the divifions made-for that purpofe) the glafs will be thereby fet 6 at [ 97 ] at right asgles to the index glafs, and confequently will be properly adjufted for ufe, and the obfer- vations may be made with the fame accuracy by this, as by the fore obfervation. To adjuft the horizon glaffes in the perpendicular pofition to the plane of the inftrument, I have con- trived to move each of them by a fingle {crew, that goes through the frame of the quadrant, and is turned by means of a milled head at the back, which may be done by the obferver while he is looking at the object. ; “To thefe improvements, Sir, I have added your method of placing darkening glaffes behind the ho- rizon glaffies, which you have been fo kind as to give me liberty to apply to my inftruments. Thefe _ gilaffes, which ferve for darkening the object feen by direct vifion, in adjufting the inftrument by the San ot Moon, I have placed in fuch a manner as to be turned behind the fore horizon glafs, or behind the back horizon giafs, that they may be ufed with -either; there are three of thefe glafles of different degrees of darknefs; the lighteft or paleft I do imagine will be of ufe in taking the Sun’s altitude when the horizon appears glaring, which I believe often happens by the reflection of the fea. If thefe additions and alterations fhould be thought to be real improvements, which I cannot doubt, Sir, if they are honoured with your approbation, I hope they may ferve in conjunction with thofe improve- ments you have made yourfelf in refpe&t to the ob- viating any poflible errors in the parallelifm of the planes of the index glafs, and in regard to the ad- juftment of the telefcope parallel to the plane of the - VoL. LAM. 6) quadrant, [ 98 J quadrant, to extend the ufe of this moft valuable nautical inftrument, and to add to the exactnefs of the celeftial obfervations taken with it to determine the longitude at fea. But of thefe particulars I need fay no more, fince you are, without doubt, in every ee the propereft perfon to give an account of em. Iam, SIR, Your moft obedient, humble fervant, London, February 25 17726 i Peter Dollond:. XV. Ree [ 99 J Received May 22, 17720. XV. Remarks on the Hadley’s Quadrant, tending principally to remove the Difficulties whith have hitherto attended the Ufe of the Back-obfervation, and to obviate the Errors that might arife from a Want of Parallelifm in the two Surfaces of the Index-Gla/s. By Nevil Mafkelyne, iF. R. S. Afironomer Royal. Read May 28, HE back obfervation with Hadley’s LS quadrant being founded on the fame principles, and in theory, equally perfect with the fore-obfervation, and being at the fame time neceffary to extend the ufe of the inftrument up to 180 degrees (it being impracticable to meafure angles with any convenience beyond 120 degrees with the fore-obfervation) it may feem furprizing that it hath not been brought equally into general ufe, more e- {pecially fince the method of finding the longitude by obfervations of the Moon, has been practifed at fea for fome years paft; fince this method woufd re- ceive confiderable advantage from the ufe of the back-obfervatien in taking diftances of the Sun and Moon between the firft and laft quarter, could fuch O 2 opfer- [ 100 j obfervations be as much depended upon as thé fore ebfervations. The caufes of this feem to have been. principally thefe two, the difficulty of adjufting the ~ back horizon glafs, and the want of a method of directing the fight parallel to the plane of the qua- drant. ‘The back horizon glafs, like the fore-one, requires two adjuftments: the firft, or common one, difpofes it at right angles to the index glafs, when the index ftands at (o) upon the arch ; which is ufu- ally performed by fetting (0) of the index of the arch: of the quadrant by double the dip of the horizon of the fea, and then holding the quadrant vertical with the arch downwards, and turning the back-horizon glafs about, by means of its lever or perpetual fcrew,, fill the reflected back horizon appears to coincide: with the fore-horizon feen direCtly. But.this ope- ration is fo difficult in praétice with the back-horizon: glafs wholly filvered, except a fmall tranfparent flit in the middle, as it has been ufually made, that few (if any) perfons have ever received proper fatisfa€tion: from it. If the back-horizon-glafs was filvered in . every refpect like the fore-horizon-glafs (which it ought to be) the upper part being lefe unfilvered, and a telefcope was applied to it, perhaps this adjuftment might be rendered fomewhat eafier and: more exact ; but it could not even thus be made fo exact as the adjuftment of the fore-horizon-glafs may, by making ufe of the Sun’s limbs. ~ The fecond adjuftment of the back-horizon- slafs, in the common conftruction of the quadrant, is fill more troublefome,. fince it cannot be exe- cuted without fetting the index go degrees off the arch, in order to place the index-glafs cae I ; n au€4 f. Lox a allel to the back-horizon- -glafs ; when this ad-- juftment may be performed in the fame manner as the correfponding adjuftment of the fore-horizon-. glafs. But the bending of the index, that follows the fetting it off the arch, is a very difagreeable cir- eumftance, having a tendency, efpecially on board of fhip, to expofe both the index and centre work to. damage ; and may even, without extraordinary pre-. cautions taken by the inftrument maker in placing- the plane of the index-glafs exaétly according to the. length of the index, difturb its perpendicularity to- the plane of the quadrant: on thefe accounts it would: be much better if thisadjuftment of the back-horizon- glafs could be performed, like thofe of the fore-. horizon-glafs, with the index remaining upon the arch of the quadrant. F ortunately, this de/deratun: has been lately effeéted by an ingenious contrivance invented by Mr. Dollond, which he has given an. account of in a letter addrefied to me*, which I have. prefented to this Society, by means of an additional. index applied. to the back-horizon glals; whereby both the adjufti nents may be made by the fame cb-. fervations and with ay the fame exaétnefs as thofe of the fore-horizon-glafs:. for a farther knowledge of: which, fee. the account itfelf, Befides the difficulty of adjufting the back-hori- zon-glafs, the want of a method on cirecting the line of fight parallel to the plane of the quadrant: has proved alfo a confiderable obftacle to the ufe ef the back-obfervation: this will ecafily appear: from, the following propofition, that the error of the angle meafured arifing from any {mall de- % See the XIV th paper, which, immediately precedes this., Vid liony [ 102 J viation of the vifual ray from a parallelifm to the. plane of the quadrant, is to twice an arch equal to the verfe-fine of the deviation; as the tangent of half the angle meafured by the quadrant is to radius, very neatly. ‘hus a deviation of 1° in the line of fight, will produce an error of about 1’ in meafuring an angle of go’, whether by the fore or back ob- fervation; but the fame deviation will produce an error of 4’ in meafuring an angle of 150°, of 6’ in taking an angle of 160°, and 12’ in taking an angle of 179°. Hence a pretty exact adjuftment of the line of fight, or axis of the telefcope, is requifite in meafuring large angles, {uch as thofe are taken by the back -obfervation: and therefore a director of the fight ought by no means to be omitted in the con- ftruGtion of the inftrument (as it commonly has been fince Mr. Hadley’s time, though recommended by him), except a telefcope be made ufe of, which if rightly placed an{wers the fame purpofe better, efpe- cially in obferving the diftance of the Moon from the Sun between the firft and laft quarter. The dire@or of the fight may be placed exact enough by conftruction; but the telefcope cannot, and Mr. Hadley, not having been aware of the importance of an exact pofition of it, has accordingly given no di- tections for the placing it. I fhall therefore endea- vour to fupply this defect in the following remarks. In the firft place, I would by all means recommend an adjufting piece to be applied to the telefcope, whereby its axis may be brought parallel to the plane of the quadrant: in the next place, the back- horizon-glafs ought to be filvered in the fame manner as the fore-horizon-glafs: and thirdly, two thick filver wires fhould be placed within the eye-tube ig [ 193 |] in the focus of the eye-glafs paral'-| to one another - and to the plane of the quadrant. If they were put at fuch a diftance as to divice the diamcter of the field of view into three equal parts, it might be as convenient as any other interval. In this manner wires were placed in the telefcope by Mr. Hadley, as appears by his account of the inftrument in Philof. Tranf, N° 420. ‘Thefe wires are to be ad-. jufted parallel to the plane of the quadrant, by turn- ing the eye-tube round about which contains the wires, till they appear parallel to the plane of the quadrant.. The axis of the telefcope, by which is meant the line joining the centre of the object-glafs -and the middle point between the two wires, is to be. adjufted parallel to the plane of the quadrant by. either of the two following methods. _ ft method: When the diftance of the Moon from the Sun is greater than go degrees, by giving a {weep with the quadrant and moving the index, bring: the neareft limbs to touch one another at the wire neareft. the plane of the quadrant. ‘Then, the index remaining unmoved, make the like obfervation at: the wire fartheft from. the plane of the quadrant;. and note whether the neareft limbs are in contact as _ they. were at the other wire :. if they are, the axis of the telefcope is parallel.to the plane of the quadrant:: but if they are not,. it is inclined to the fame; and. muft be correéted.as follows. If the neareft limbs. of the Sun and Moon feem.to lap over one another: at the wire fartheft-from the plane of the quadrant,. the object end of the telefcope is inclined from the- plane cf the quadrant, and muft be altered by. the- adjuitment made for that purpofe:. but, if the neareft. Limbs. (Lite hy. . ‘limbs of the Sun and Moon do not come to touch -one another at the wire fartheft from the plane of the quadrant, the obje&t end of the telefcope is inclined towards the plane of the quadrant, and muft be ‘altered by the adjuftment accordingly. Let thefe operations be repeated until the obfervation is the fame at both the parallel wires, and the axis of the ‘telefcope will be adjufted parallel to the plane of the ‘quadrant. In like manner, the axis of the telefcope may be alfo adjufted parallel. to the plane of the ‘quadrant for the fore-obfervation. Second method. Set the index to (0) and hold the ‘plane of the quadrant parallel to the horizon of the dea, with the divided arch upwards, the two wires being paralle] to, and including both the dire&t fore- horizon, and the reflected back-horizon, between them. Raife or lower the plane of the quadrant until the direé&t and reflected horizons coincide to- gether: if the coincidence happens in the middle between the two wires, or rather, to be more exadt, above the middle by fuch a part of the field of view as anfwers to the number of minutes in the depreffion of the horizon (which may be eafily eftimated if the angular Interval of the wires be firlt found by experi- ment, in manner hereafter mentioned) the axis of the telefcope is parallel to the plane of the quadrant; but if it does not, the line of fight is inclined to the plane of the quadrant, and mutt be corrected as follows, 4f the dire and reflected horizons, when they coin- cide, appear higber above the middle between the wires, than what the quantity of the depreffion of the horizon amounts to, the obje&t end of the telefcope is inclined from: the plane of the quadrant, and muft be altered by the adjuftment made for that purpofe ; but f toy | but if the two horizons appear to coincide in a lower part of the field of the telefcope, the obje& end of the telefcope is inclined towards the plane of the quadrant, and muft be altered by the adjuftment accordingly. Repeat thefe. operations till the twe horizons appear to coincide above the middle between the two wires, by the quantity of the depreffion of the horizon, and the axis of the telefcope will be ad- jufted parallel to the plane of the quadrant. In order to find the angular interval between the wires, hold the quadrant perpendicular to the horizon, as in obferving altitudes ; and turn about the eye-tube with the wires until they are parallel to, and include, the direct fore-horizon and reflefted back-horizoa between them. Move the index from (0) along the divided arch, at the fame time raifing or lowering the telefcope by the motion of the quadrant until the direct horizon appears to coincide with the upper wire, and the reflected back-horizon with the lower wire; the number of degrees and minutes fhewn upon the arch, increafed by double the depreffion of the hori- zon, will be the angular interval of the wires; its proportion to the depreflion of the horizon will be therefore known ; and hence the {pace in the field of the telefcope anfwering to the depreffion of the hori- zon, may be eafily eftimated near enough for adjufting the axis of the telefcope in the manner before-men- tioned. ‘The firft of the two methods here given for adjufting the pofition of the telefcope will probably be found moft convenient; and the greater the diftance of the Sun and Moon is, the more nearly may the adjuftment be made, becaufe the fame deviation of the axis of the telefcope will caufe a greater error. Vou. LXII, “P| ee od Ba [i reer i: The telefcope fhould be fixed by the inftrument- maker fo as to command a full field of view when the inftrument is placed at go° if the inftrument be — an octant, or 120° if it be a fextant; becaufe the index-glafs then ftands more oblique with refpe& to the incident and reflected rays, and confequently the field of view of the telefcope, as far as it depends upon the index-glafs, will be more contracted than in any cther pofition of the index: but if there is a fair field of view in this cafe, there neceffarily muft be fo in every other pofition of the index. : The two parallel wires will be very ufeful on many occafions, as well in the fore as the back- obfervation. In taking the altitude of the Sun, Moon, or ftar, direct the fight towards the part of the horizon underneath, or oppofite to the object, according as. you intend to obferve by the fore or back obfer- vation, and hold the quadrant that the wires may - conftantly appear perpendicular to the horizon, and move the index till you fee the obje&t come down: towards the horizon in the fore-obfervation, or up to it in the back-obfervation, and turn the inftrument in. order to bring the object between the wires; then move the index till the Sun or Moon’s limb, or the ftar touch the horizon. The nearer the object is brought to an imaginary line in the middle between: the wires (it is indifferent what part of the line it is brought to) and the truer the wires are kept perpen- dicular to the horizon, the more exaét will the ob- fervation be. In the fore-obfervation, the object ap- pears in its real pofition ; but in the back-obfervation, the object being brought through the zenith to the horizon, the real upper-limb will appear the aie : an 7 [ 207 ] and the contrary. Either limb of the Sun may be ufed in either obfervation; but it will be moft con- venient in general to make the Sun appear againft the fky, and not again{t the fea; and then the ob- jeCts appearing inverted through the telefcope, the Sun will appear loweft, and the horizon higheft. The obferved altitude is to be corrected for dip, re- fraction, and Sun’s femi-diameter, as ufual. In taking the diftance of the neareft limbs of the Sun and Moon, whether by the fore or back-obfer- vation, having firft fet the index to the diftance nearly, by the help of the Nautical Almanac, and brought the Moon to appear anywhere on or near the diameter of the field of view of the telefcope, which bifects the interval between the wires, give a fweep with the quadrant, and the Sun and Moon will pafs by one another; if in this motion the neareft limbs, at their neareft approach, juft come to touch one another, without lapping over, on or near any part of the diameter of the field of the te- lefcope which bifects the interval between the wires, the index is rightly fet; but if the neareft limbs either do not come to meet, or lap over one another, alter the index, and repeat the obfervation till the neareft limbs come to touch one another properly. This method of obferving will be found much more eafy and expeditious than without the wires, fince in that cafe it would be neceffary to make the limbs touch very near.the centre of the telefcope, but here it is only neceflary to make them do fo anywhere on or near the diameter of the field of the telefcope © which bifects the interval between the two wires. Ee 2 The ae The fame method may be ufed in saline the Moon’s diftance from a fixed ftar. It may not be amifs here to make fome remarks on the rules that have been ufually given for ob- | ferving the Sun’s altitude, both with the fore and back-obfervation, which have all been defective, and to point out the proper directions to be followed, when a telefcope is not ufed with two parallel wires to direct the quadrant perpendicular to the horizon, and to fhew the principles on which thefe direétions. are founded. Obfervers are commonly told, that in making the: fore obfervation they fhould move the index to bring the Sun down to the part of the horizon di- rectly beneath him, and turn the quadrant about upon the axis of vifion ; and when the Sun touches the horizon at the loweift part of the arch defcribed by him the quadrant will fhew the altitude above the vifible horizon. I allow that this rule would be true, if a perfon could by fight certainly know the part of the horizon exactly beneath the Sun; but, as this is im- poflible, the precept is incomplete. Moreover, in taking the Sun’s altitude in or near the zenith, this rule entirely fails, and the beft obfervers advife to hold the quadrant vertical, and turn one’s felf about upon the heel, ftopping when the Sun glides along the horizon without cutting it: and. it is certain that this is a good rule in this cafe, and capable with care of an{wering the intended purpofe. We have thus two rules for the fame thing, which is a proof that nei- ther of them is an univerfal one, or fufficient in all cafes alone. In [ 109 ] In taking the back-obfervation, obfervers have been advifed either to turn the quadrant about upon the axis of vifion, or,holding the quadrant u pright, toturn them- felves about upon the heel, indifferently. The true ftate - of the cafe is this; that, in taking the Sun’s altitude, whether by the fore or back-obfervation, thefe two methods muft be combined together; that is to fay, the — obferver muft turn the quadrant about upon the axis of vifion, and at the fame time turn himfelf about upon his heel, fo as to keep the Sun always in that part of the horizon-glafs which is at the fame diftance as the eye from the plane of the quadrant: for, un- lefs the caution of obferving the objects in the proper part of the horizon-glafs be attended to, it is evident the angles meafured cannot be true ones. In this way the reflected Sun will defcribe an arch of a. parallel circle round the true Sun, whofe convex fide will be downwards in the fore-obfervation, and upwards in the back-obfervation, and confequently, when, by moving the index, the lowefi point of the arch in the fore-obfervation, or the uppermoft point of the _arch in the back-obfervation, is made to touch the horizon, the quadrant will ftand in a vertical plane, and the altitude above the vifible horizon will be properly obferved.. - bidet The reafon of thefe operations may be thus ex-. plained ; the image of the Sun being always kept in. the axis of vifion, the index will always fhew on the quadrant the diftance between the Sun and any object feen- directly which its image appears to touch; there- fore, as long as the index remains unmoved, the image of the Sun will defcribe an arch everywhere eguidiftant from the Sun in the heavens, and confe- BY | quently 3 - Bees 3 quently a parallel circle about the Sun, as a pole; {uch a tranflation of the Sun’s image can only be pro- duced by the quadrant being turned about upon a line drawn from the eye to the Sun, as an axis; a motion of rotation upon this line may be refolved into _ two, one upon the axis of vifion, and the other upon a line on the quadrant perpendicular to the axis of vifion ; and confequently a proper combination of thefe two motions will keep the image of the Sun conftantly in the axis of vifion, and caufe both joint- ly to run over a parallel circle about the Sun in the heavens; but when the quadrant is vertical a line thereon perpendicular to the axis of vifion becomes a vertical axis; and, asa {mall motion of the quadrant is all that is wanted, it will never differ much in practice from a vertical axis; therefore the obferver, by properly combining and proportioning two mo- tions, one of the quadrant upon the axis of vifion, and the other of himfelf upon his heel, keeping him- felf upright (which gives the quadrant a motion upon a vertical axis) will caufe the image of the Sun to defcribe a fmall arch of a parallel circle about the Sun in the heavens, without departing confiderably from the axis of vifion. If it fhould be afked, why the obferver fhould be directed to perform two motions rather than the fingle one equivalent to them on a line drawn from the eye to the Sun as anaxis? I anfwer, that we are not capable, while looking towards the horizon, of judging how to turn the quadrant about upon the elevated line going to the Sun as an axis, by any other means than by combining the two motions above-mentioned, fo as to keep the Sun’s image al- ways ) [ arz } | ways in the proper part of the horizon-glafs. Wher the Sun is near the horizon, the line going from the eye to the Sun will not be far removed from the axis. ° of vifion; and confequently the principal motion of the quadrant will be performed on. the axis of vifion, and the part of the motion made on the vertical axis. © will be but fmall. On the contrary, when the Sun is near the zenith, the line going to the Sun Is not far removed from a vertical line, and confequently the principal motion of the quadrant will be per- formed on a vertical axis, by the obferver’s turning himfelf about, and the part of the motion made on the axis of vifion will be but fmall. In intermediate altitudes of the Sun, the motions of the quadrant on the axis of vifion and on a vertical axis will be “more equally divided. Hence appears. the reafon of the method ufed by the beft obfervers in taking the Sun’s altitude when near the zenith by holding: the quadrant vertical and turning about upon the heel, and the defects of the rules that have been commonly given for obferving altitudes in other cafes. As it may conduce to: the fetting this matter in: a ftill clearer light, I fhall here defcribe in. order the feveral motions that, will be given to the reflected. image, by turning the quadrant about upon the axis of vifion, a vertical.axis, or the line drawn, from. the eye to the Sun, fucceffively.. I, If the quadrant is turned about upon the axis of vifion, the fame being directed. to the point of the horizon exaétly beneath or oppo- fite the Sun, the image of the Sun will. move. from right to left, or from left. to right,. acrofs: the: cag | the horizon-glafs, the fame ways the arch of the quadrant is carried, both in the fore and back-obfervations, with a velocity which isto the angular velocity of the quadrant as the fine of the © Sun's altitude to the radius, defcribing an arch convex downwards in both cafes; and when the motion of the Sun in this arch is parallel to the horizon, the quadrant is held truely perpendicular to the horizon, and confequently in a proper poflition for-taking the Sun’s altitude. But, if the axis of vifion be directed to, and turned round a-pointin the horizon befide the vertical circle paffing through the Sun, the Sun’s image, when its motion is parallel to the horizon, will be neither in the axis of vifion nor the Sun’s . vertical, but between both; at the fame time, the plane of the quadrant will not be vertical, and the altitude found: by bringing the Sun’s image to touch the horizon will not be the true altitude. i]. If the quadrant be held perpendicular to the horizon, and turned about upon a vertical axis, or one nearly fo, the Sun will defcribe an arch con- vex downwards in the fore-obfervation, and up- wards in the back-obfervation, the motion of the Sun being the fame way as the axis of vifion is carried in both cafes, and being to the angular motion of the quadrant, as the verfe-fine of the Sun’s altitude to the radius in the fore-obferva- _ tion, but as the verfe-fine of the fupplement of the Sun’s altitude to180° to the radius in the back-obfervation. The Sun therefore will move flower than the axis of vifion is the fore-obfer- vation, and confequently will be left nig tines wit tp [ 113 J | with refpect to the axis of vifion, or feem - to move backwards; and the Sun will move quicker than the axis of vifion in the back- obfervation, or will feem to get before it. When the motion of the Sun in this arch is parallel to the horizon, the plane of the quadrant coin- cides with the vertical circle paffing through the Sun, and confequently the quadrant is in a pro- per pofition for taking the Sun’s altitude. But if the quadrant be held a little deviating from the perpendicular pofition to the horizon, and ' turned about upon an axis, either vertical or only - nearly fo, the arch defcribed. by the Sun ap- parently will cut the horizon, but will never move parallel to it, and confequently the quadrant will not be brought into a proper pofition for obferving the Sun’s altitude. III. If the quadrant be turned on the line going to the Sun as an axis, the reflected Sun will be kept conftantly in the axis of vifion, and will defcribe an arch of a parallel circle about the real Sun, with a velocity which is to the angular motion of the quadrant, as the fine of the Sun’s altitude is to the radius; and when the motion of the reflected Sun is parallel to the horizon, the quadrant is vertical. Hence naturally arife the three methods of taking an altitude, which have been mentioned before. In the firft, the axis of vifion is fuppofed always direéted to one and the fame part of the horizon, namely that which is in the Sun’s vertical. In the fecond, the obferver is required to hold the quadrant truly vertical, and to turn himfelf upon a vertical axis; Vou. LXII, Q . but {i144 | But it is evident neither of thefe motions can be ac«. curately performed. In the third method, the ob- ferver is only required to move both himfelf and the quadrant, fo as to keep the Sun always in or near the axis of vifion, which may be performed very well, becaufe the axis of vifion is a vifible and cer- tain direction for it. One exception, however, fhould be made to this general rule, namely, in taking the Sun’s altitude when very low, by the back obfer- vation; in which cafe it will be beft to ufe the fecond method, or elfe to hold the quadrant perpendicular by judgment; which will be much facilitated by ufing a telef{cope containing wires in its focus parallel to the plane of the quadrant, as defcribed in p. 106: for, in this cafe, the perpendicular pofition of the quadrant cannot be attained fo near by the method of turning the quadrant on a line going to the Sun as an axis, as it can by the other method. It remains to treat of the errors which may arife from a defect of parallelifm in the two furfaces of the index-glafs, and to point out the means of ob- viating them in the celeftial obfervations. It is well known, that if a pencil of parallel rays falls.upon a elafs- whofe two furfaces are inclined to one another, and fome of the rays are refleCted at the fore-furface, and others paffling into the glafs and fuffering.a re- fleGtion at the back-furface and two refractions at the fore-furface emerge again from the glafs, thefe latter rays will not be parallel to thofe reflected at the fore-furface, as they would have been if the furfaces of the glafs had been parallel, but will be inclined to the fame. I find that the angle of their mutual in- ¢clination, which may be called the deviation of the ; rays rays reflected from the back-furface, will be to double the inclination of the furfaces of the glafs (which is here fuppofed to be but fmall), as the tan- gent of the angle of incidence out of air into glafs, is to the tangent of the angle of refraétion, Hence, in rays falling near the perpendicular, the deviation will be about three times the inclination of the furfaces; and if the angles of incidence be 50°, 60°, 70°, 80° or 85°, the deviations of the reflected Tays will be about 4> 5, 7,13 or 26 times the incli- nation of the furfaces, refpectively, Had the devi- ation been the fame at all incidences of the rays on the index-glafs, no error would have been produced in the obfervation; becaufe the courfe of the ray would have been equally affected in the adjuftment of the inftrament, as in the obfervation. But, from what has been juft laid down, this is far from being the cafe, the deviation increafing according to the obliquity with which the rays fall upon the index- glafs; fothat in very oblique incidences of the rays, fuch as happen in meafuring a large angle by the fore-obfervation or a fmall angle by the back-obfer- vation, the leaft defect in the parallelifm of the planes of the two furfaces of the index-glafs may produce - a fenfible error in the obfervation. What is here faid only takes place in the fulleft extent, if the thickeft or thinneft edge of the index- glafs, or, to exprefs the fame thing in other words, the common fection of the planes of the furfaces of the index-glafs ftands perpendicular to the plane of. the quadrant ; but, if the common feétion of the planes is inclined to the plane of the quadrant, the error arifing from the defect of the parallelifm of the Qe es furfaces fuel farfaces will be leffened in the proportion of the fine of the inclination to the radius; fo that at laft, when the common {ection becomes parallel tc the plane of the quadrant, the error intirely vanifhes. For this reafon, Mr. Hadley very properly directed the - thickeft and thinneft edges of the index-glafs to be placed parallel to the plane of the quadrant. But, asit may well be queftioned whether this care is always taken by the inftrument-maker, and it cannot be fup- pofed that the glafles can be ground perfect parallel planes, it would certainly be anadvantage acquired to the inftrument, could the error arifing froma want of parallelifm of the planes be removed in whatever pofition the conimon feétion of the planes fhould be placed with refpect to the plane of the quadrant. - This will be effected for celeftial obfervations, -if the upper part of the index-glafs be left unfilvered on the back, and made rough and blacked, the lower part of the glafs being filvered as ufual, which muft be covered whenever any celeftial obfervations are made. Then, if the telefcope be fufficiently raifed above the plane of the quadrant, it is evident that the ob- fervations will be made by the rays refle@ted from the fore-furface of the upper part of the index-glafs, and confequently, if the quadrant be adjufted by making ufe of the fame part’of the index-glafs, the obfervations will be true whether the two furfaces of the index-glafs are parallel planes or not. The Sun or Moon may be thus obferved by reflection from the unfilvered Se of the index-glafs and ho- rizon-glafs, fo that a paler darkening glafs will fuf- fice, and they will appear much diftin¢ter than from an index-glals wholly filvered with a deeper darken- ing 3 [ reg ing glafs; for although the furfaces of a glafs may be parallel, yet there always arifes fome little con- fufion from the double reflection. Neither will the Moon appear too weak by two unfilvered re- fletions, even when her crefcent is very fmall, | except fhe fhould be hazy or clouded; and then the light may be increafed by lowering the te- le{cope fo as to take in part of the filvered re- fle@ion of the index-glafs, which in this cafe ~ -muft be uncovered: the fame is alfo to be under- ftood with refpect to the Sun, fhoald his light be too much weakened by hazinefs or thin clouds. The horizon-glafies fhould be adjufted, or the error of adjuftment found by the Sun or Moon; the firft will be in general the beft object for the purpofe ; -and; as the Sun or Moon feen directly through the unfilvered part of the horizon-glafs will be much brighter than the image of the fame feen by two unfilvered reflections, it muft be weakened by a dar- - kening glafs placed beyond the horizon-glafs, the reflected image being farther weakened, if neceflary, by a paler darkening glafs placed in the ufual man- ner between the index-glafs and the horizon-glats. If a quadrant was defigned principally for taking the diftance of the Moon from the Sun and fixed ftars, and was not wantei for obferving terreftrial angles, it would be the beft way to have none of the elaffes filvered, but to leave the horizon glaffes intirely tranf- - parent, and to put a red glafs for an index-glafs of the fame matter with the darkening glaffes, which would reflect light from the fore-furface only. "The Sun’s altitude might alfo be obferved with this inftrument, either by the fore or back-obfervation; : and ee and the atrifide of the Moon might be taken with it in the night. But the Mlenidcs | of ftars could not be Tales with it, nor the Moon’s altitude in the day time, which would however be no great in- convenience, as thefe obfervations might be well enough fupplied by common quadrants. The following rules for the fize of the glaffes and the filvering them, and the height of the telefcope may be of ufe. The index glafs and two horizon- glaffes fhould be all of equal height, and even with one another in height both at top and bottom. ‘The telefcope fhould be moveable parallel to itfelf nearer to or farther from the plane of the quadrant, and the range of its motion fhould be fuch that its axis when at the loweft ftation fhould ‘point about _3.th of an inch lower than the top of the flvering of the horizon-glaffes, and when at the highett {tation fhould point to the height of the middle of the un- age ered part of the index- glafs. ‘The height of the affes, and the quantity of parts filvered ope parts unfilvered, fhould vary according to the aperture of the object-glafs, as in the fol llowing table; where the frit malin of figures fhews the sae in parts of an inch anfwering to an aperture of the object- elafs of .*.ths of an inch in diameter; the fecond column what anfwer to an aperture, of the object- glafs of 4,ths of an inch in diameter ; and the third, what are fuitable to an aperture of the object-glafs fF 5.ths Of an inch in diameter. © Diameter [ 119 | yes } Parts of an Inch \ Diameter of apeiipte of object-glafs 130] 0540, 0, 50 Height of glaffes 990] 1,13] 1,37 “Height of filvered part of indox-glf 550) 0,63)0,77 Height of unfilvered part of ditto ,40] 0, 50] 0,60 Heicht of filvered part of horizon-glafies 25] 0,3 310,42 He ight of unfilvered part of ditto 65| 0,80) 0.95 A If the telefcope hee a common object- olals, the firft aperture of Jeths of an inch will be moft con- -yenient; but if it has an achromatic ee elafs, one of the ether apertures of ,* ths or .3,thsof an inch, will be moft proper. The field of view of the telefcope fhould be 5 or 6 degrees, and the objects fhould be rendered as diftint as poffible throughout the whole field, by en ying two eye-glaffes to the telefcope. The breadth of the glaffes fhould be de- | termined as ufual, according to the obliquity with which the rays fallon them and the aperture of the object-glafs. I fhall conclude this paper with fome eafy rules for finding the apparent angular diftance between any two near land objects by the Hadley’s qua- drant. To find the angular diftance between two near objects by the fore-obfervation. Adjuft:the fore- horizon-glafs by the object intended to be taken as the direCt object; and the angle meafured by the fore-obfervation on the arch of the quadrant between this objeét and any other object feen by reflection will be the true angle between them as feen from the centre of the index-glafs. But, if the quadrant be already Rai <., already well adjufted by a diftant obje&, and youdo not chufe to alter it by adjufting it by a near one, move the index, and bring the image of the near direct object to coincide with the fame feen diredtly, and the number of minutes by which (0) of the index ftands to the right hand of (0) of the quadrant upon the arch of the excefs is the correction, which added to the angle meafured by the arch of the qua- drant between this direct object and any other object. feen by refleGtion will give the true angular diftance between them reduced to the centre of the index- glafs. : To find the angular diftance between two near objects by the back-obfervation. It is fuppofed that the-horizon-glafs is truly adjutted ;° if itis not, “let st be! fo. Obfcive the diftance of the objects by the back-obfervation, and take the fupplement of the degrees and minutes ftanding upon the arch to 180 degrees, which call the inftrumental angular diftance of the objects; this is to be corrected as follows, Keep the centre of the quadrant or index-glafs in the fame place as it had in the foregoing obfervation, and obferve the diftance between the near object, which has been juft taken as the dire&t object, and fome diftant object, twice; by making both objects to be the direct and reflected ones alternately, holding the divided arch upwards in ~ one cafe and downwards in the other, ftill preferving the place of the centre of the quadrant. The difference of thefe two obfervations will be the cor- rection, which added to the inftrumental angular ; E iar diftance, { x2t ] diftance, found as above in the firft obfervation be- tween the firft object and any other objet feen by reflection, will give the true angular diftance between: them reduced to the centre of the index-glafs. But if you fhould happen to be in a place where you cannot command a convenient diftant object, the following method may be vfed. The back-horizon-glafs being ndqateed, find the inftrumental angular diftance between the objects; this is to be correéted by means of the following Operations, Set up a mark at any convenient diftance oppofite or nearly fo to the object which has been taken as the direct object; and looking at the direct object move the index of the quadrant, and bring the image of the mark to coincide with the direct object, and read off the degrees and minutes ftanding on the arch of the quadrant, which fubtra& from 180 degrees, if (0) of the index falls upon the quadrantal arch ; but add to 180 degrees, if it falls upon the arch of excefs; and you will have the inftrumental angular diftance of the objectand mark. — Invert the plane of the quadrant, taking care at the fame time not to change the place of its centre, and looking at the fame direct object as before, move the index of the quadrant, and bring the image of the mark to coincide again with the direct object, and read off the degrees and minutes ftanding onthe arch, and thence alfo find the inftrumental angular diftance of the obje&t and mark. Take the fum of this and the former inftrumental angular diftance ; half of its differ- ence from 360° will be the correction, which added to the inftrumental angular diftance firft found be-- tween the fame direct object and the other object feen Vou. LXII, R by eee: by reflection will give the true angular diftance be- tween them reduced to the centre of the index-. lafs. . It is to be obferved, that if the mark be fet up at the fame diftance from the quadrant as the direct object is, there will be no occafion to invert the plane of the quadrant, but the obferver need only make the: image of the mark coincide with the direét object, then turn himfelf half round, and now taking the mark for the direct object caufe the image of the former direét object to coincide with the mark, the divided arch of the quadrant being kept upwards,. and the place of the centre of the quadrant remain- ing alfo the fame in both cafes: half the difference. of the {um of the two inftrumental angles from 360 degrees will be the correction of the adjuftment. as before. Should only one of the objects be near, and the: other remote (that is to fay, half a mile diftant or more) let the diftant objet be taken for the direct one, and the near object for the refleéted one; and. the true diftance of the objects as feen from the centre of the index-glafs will be obtained without requiring any correction, whether it be the back or: fore obfervation that is made ufe of; only obferving, as ufual, to take the fupplement of what is fhewn upon the arch to 180 degrees in the back-obfer-. vation. XV. Account { #23 ] XV. Account of the Irruption of Solway Mots zz December 16, 1772; m a Let- ter from Mr. John Walker, to the Earl of Bute, and communicated by bis Lord- feip to the Royal Society * My Lord, Read Feb. 13, Nah HEN I was fitting yefterday : writing to -your Lordfhip, I re- ceived the honour of yours. I fhail therefore defer the account I intended of my expedition laft feafon to thenorth, and give the beft defeription I can, of the extraordinary irruption of Solway-mofs, which I went to vifit, about a week after it happened. It is not furprizing, that it has every where attracted the attention of the public; for though the caufe of it ~ is obvious, yet fo far as I recolleét, the alteration it has produced on the face of the earth, is greater than any we have known in Britain, from natural caufes, fince the deftruction of Earl Goodwin’s eftate. * The Society has received, from other hands, feveral accounts of this curious and fingular phenomenon; but this, as one of the lateft, being likewife the completeft, was thought the moft proper to be laid before the public; efpecially as, on comparifon, few \ particulars of any importance mentioned in the other accounts — were found wanting in this. Thefe few, however, have been collected, and fubjoined in the form of notes. M. M. R 2 It [ 124 J It happened on the 16th of December, when _ there fell fuch a deluge of rain, over all the North of England, as has not been known, for at leaft two hundred years. There was a very great flood at Moffat, but I think, 1 have feen one or two greater, and cer- tainly it was not fo extraordinary here, as further South. -The Solway flow contains 1300 actes of very deep and tender mofs, which, before this accident,, were impafiable, even in fummer, to a foot paflenger.. It was moftly of the quag kind, which is a fort of mofs covered at top with a turf of heath and coarfe aquatic graffes; but fo foft and watery below, that, if a pole is once thruft through the turf, it can eafily be pufhed, though perhaps 15 or 20 feet long, to the bottom. If a perfon ventures on one of thefe quags, it bends in waves under his feet ; and if the furface breaks, he is in danger of finking to the bottom *.. The furface of the flow was, at different places, between 50 and 8o feet higher than the fine fertile plain, that lay between it and the river Efk. See Tab. VI. About the middle of the flow, at the place marked A, were the deepeft quags, and there the mofs was ele-. vated higher above the plain, than in any part of the: neighbourhood. From this, to the farm called the Gap, upon the plain at C, there was a broad gully, * The furface was always fo much of a quagmire, that, in moft places, it was hardly fafe for any thing heavier than a fportsman to venture upon it, even in the drieft fummers. A, great number of Scotchmen, in the army commanded by Oliver ‘Sinclair in the timeof Henry VIII. loft their lives init; and it is faid that fome people digging peats upon it, met with the fkeleton of a trooper and his horfe in compleat armour, not many years ago. though Me MTT fetae i ; Bt Philos. Tras Vol LMM Tab V1 pe. 124. Road W Carlisle | > f Langtown Philos. Traws. Vel IX Tab NI [t-124. Road to 6 yrlisle ; P ii a = on ; eee % aN / S 5 4G TG OE OF us } > Teas LO; PAE aes SANG eee Sa Act RU AGO rere Warr ay e CIR FA or we ies rene 3 oe 3 saree Lhitos Trans Tol INI Vab NIL 175 5, Brave Je VY ye nape x oyy ue Jon phogreyp none aya bunigy bag-app 4y roomy! scopy ” Y9 rye yy poral peyatye surf opis Yeo ua» 24) 10 eq EAI MPU 9 04 ) ap fo MAA AWWA 1, 2 ( le Henin Wa y he. a ~ > SS » 2) n ay fe age to the-€ , Me é ee which, Wid ‘Lif y veh tn the Lider é the ( Bias / runse Ue. Clectricity h Hat fe rt y / were VB. She dotted Sine represents Me ce ete oulstile- f ‘i iy A te ns Tan i} @ hy outdstidle’ eter of that part of the Building oteted USE ; <7 ; E } j : 2 so . - ? ae es dotied Fine *F eresents the course the Clectritty lock tn nee wifrage fe 4 Z a Zs Basiree Jen fangs] | a few inches of air to the ftriking rod of the clock, in which, near the end, it meited a large {pot, whence -it was conduted by the work of the clock to the upper part of the pendulum,. in the axis of which it melted another large {pot, and. defcended by the rod paffing over. the ball, which it melted in a moft remarkable manner in fix or feven places (per= haps upon the ball it might accumulate, and, for. want of a propet conveyance, break out in different parts of it) and quitted it at the bottom of the nut, which is melted in three places, and will accom- pany this paper. Here the eleCtricity leaped through eight inches of air, or paffed in conductors of the worft kind, dry brick-and wood (with a confiderable cavity between them), till it reached the frame of a window, over the doors, where it broke the ceiling, ‘and burnt the wood toa coal. Here it met with the point of a nail, driven upward into the window frame as a fecurity to the center bar. The point of this nail is melted off, I fuppofe, full half an inch; it was alfo melted in two large {pots on the oppofite fides near the head. . My friend Mr. Jones drew it from the bar, &c. ‘This gentleman was alio fo obliging as to take down a {ketch of the window, and an out- line of the parts affected of the building. [See Tab. VII} The nail is nowinthe cuftody of Mr. Nairne. The lightning pafled down the aforementioned bar, and by a bent iron (in contact with both), into another bar, whofe point (which was greatly melted) came much nearer the upper bolt of the door, The lead-work, from the point of the bar was melted, and a board nearly in contact with the ftaple of the bolt much blacked by the pafling of the eleftricity. ; Here ‘[ 134] Here it ftrack the upper edge of the ftaple, which projected a little above the top of the bolt, melted it in a moit extraordinary manner; the fpot, and in- deed feveral others, having run into a kind of fpiral form, which 1s raifed confiderably, as may be plainly diftineuifhed by a very fhallow magnifier, and often, as in this, by the naked eye. This effec& was firft obferved by Mr. Nairne. When it quitted this bolt, it ftruack upon a femicircular handle of iron (firft tearing out a large piece from the door), the upper part of which hath three melted fpots, be- fides a fingle one at the upper edge of it. But, in quitting it, the electricity melted only one fpot at the lower edge *, which I think, as Mr. Bell (a gentleman who was with us) obferved, was a cri- terion whereby to judge of the direction of the fluid. To the left of this door, at the diftance of eleven feet four inches, came down a leaden pipe, which ter minated at the ceiling, and there juft entered a pitched trunk of fir (which indeed was the cafe with every leaden pipe about the building). Here the lightning exploded, rending the trunk, and domg other flight damage in and about a window, to which it was attracted by an interrupted and irregular communi- cation of metal.. 1 would beg leave to remark, that, had this pipe of lead been continued to the bottom of the building, and thence conveyed into. the earth, in the manner directed by Dr. Franklin, ' I can have no doubt but the whole contents of the explofion would have pafied this way, have been * Quere, is not this effe€t fomewhat analogous to Mr. Lullin’s eleétrical experiment with a card ¢ 2 conducted [ 135 | conducted with perfect fafety to the building, &c. and that no other part of it would have been at all affected. As the effects of this ftroke fo exactiy correfpond with thofe many times before obferved by Dr. Franklin, I think we fhall fcarce ever meet witha greater proof of the utility of his metallick conductors; -and cannot help exprefling a fincere with, that build- ers, and perfons engaged in the erection of f public edi- fices, &c. might be eae with, to make a re- gular communication of metal, from the top of fuch buildings to a confiderable depth into the earth, and of iach a diameter and’ kind, as may be fufficient to fecure both the buildings, and the lives of thefe, who may happen to bein them. ‘The poor man deftroyed by this accident, was fitting at the time on a fhort ladder, which lay horizontally on. the pavement, with his back againft the door. The lightning flew from the middle bow, and ftruck him on and under his left ear, entered his neck, making a wound half an inch long, raifed ina bur and burnt, paffed down his back, which it turned black as ink, down his left arm, melting the ftud in his fhirt fieeven the {tone in which, as veil as the filver, feems to be a little affe¢ted. Hence it few into his body, which it burnt in a hard fpot, ie- fembling fcorched leather, paffing through it into his right leg, and breaking out a little above the ancle; making a large wound, and another bur, burnt as before, with two others {maller a little be- low it, and fome ftill fmaller in his feet. His cloaths and hair were much burnt, but his ftock, fhoe, and knee-buckles, the metal buttons on his coat and waiftcoat, a fhilling, which he had in the left Eason). | left pocket of his breeches, and the metal clafps of a Common Prayer-Book, in his coat-pocket, were all uninjured *, His death was truly inftantaneous; he hath left a widow and two children in diftrefled cir- cumftances, who were entirely dependent on his la- bour. His name was Goodion, aged thirty-four, by trade a taylor, at N° 3. Craven-Buildings, Drury- Lane. P. S. The ftuds above-mentioned will be fent to- gether with this paper (as a curiofity) for the in- fpection of the members of the Royal Society. * ‘The corps, after lying two or three days on a table, feemed not more difpofed to putrefaction, than bodies at that time gene- rally are, which die a natural death. XVI. 4 - fsasrd XVIII. 4 Letter from Thomas Ronayne, Efg; to Benjamin Franklin, DL. D, Bok. S. inclofing an Account of Jome ; Obfervations on Litmofpherical Elettricity 3 in regard of Fogs, Mifts, &c. with fome Remarks s. communicated by Mr.. William Henley... SLR, Read April 30> @ N conformity to the defire of fome Thee _ friends, I have drawn up the follow- ing obfervations on atmofpherical ele@tricity, which F beg leave to lay before you; and fhall think the: trouble I have had; in profecuting the neceflary ex-. periments, fafticiently compenfated, if it fhall appear to you that:they contain any thing new. or curious ; in which cafe, you are at liberty to difpofe of them. in- whatever manner you fhall think. proper. fam, SUR; With very refpe€tful conifiterattons, Your moft obedient. fervant, . Cecil-Street, . Keb. 15, 1772¢. "EROS Ronaynes. Vor. LX. TE SOME. | [ 138 ] * SOME years ago I difcovered, by Mr. Canton’s eletrometer, defcribed in the. Philof. Tranfections, Vol. XLVIII. p. 783. that the air of Ireland is, during the winter feafon, in almoft a conftant ftate of pofitive electricity ; which, however, is fo weak, ‘that, in order to obferve it fatisfactorily, T have al- ways found it neceflary to have the cork-balls fuf- pended from threads of a middling finenefs, fix or feven inches in length, quite ftreight, and to avoid, as much as poffible, any interruption from the wind. I have likewife had frequent recourfe to the fol- Jowing contrivance, by which I was enabled, within doors, to purfue my inquiries with greater accuracy and advantage: having procured a {lender tapering piece of wood, about five feet long, to the {maller end of which an electrometer was affixed, by means of a {mall hook; I placed it out from an open garret avindow, and faftened the other end with a {mall hafp to one of the jambs: [ had alfo at hand another piece of wood, in the ends of which, a {mall glafs tube and a ftick of fealing-wax had been infested. Either of thefe was occafionally excited, and applied. near the cork-balls, in order to determine more pre- cifely the kind of eleétricity with which they might happen to be affected; and I was always careful in * I commenced my experiments on the air in the year 1761, and thofe on the clouds in the year 1762. I continued them un- remittingly, as opportunity offered, till the year 1770, when my occafions brought me to England. I have repeated my ex- periments, with regard to the common air, in different places ‘here, and find it the fame as chat in Ireland, making 4 [ ager]. | making my experiments on that fide of the houfe where the wind had leaft power. I have found the air, in winter, at a proper diftance from buildings, trees, ain of fhips, &c. very fen- fibly electrified, during a frofty or foggy ftate of the weather; and in mifts too, but in a lefs degree: I have alfo difcovered fmall figns of it in calm and cloudy weather. The air, in fummer, never fhewed any fign of electricity, except when a fog- happened in the cool. . of the evening, or at night; in which cafe, I always- difcovered manifeft marks of electricity, fenfibly, weaker than thofe cbferved in winter fogs, but pre- cifely of the fame kind; that is, pofitzve.. I have often examined the ftate of the air,. at the time of an. Aurora borealis, and could not difcover any indication of electricity, except when a fog had: appeared atthe fame time; im which cafe, the elec- tricity has been, in every refpedt,. the fame as that of. a fog at anyother time. Once, indeed, during an. Aurora borealis.on a remarkable ferene-night, 1 dif-. covered fome. figns of a very. weak pofitzve electri-- city.. As the: ele@tricity of the air is-generally pofifrve (1 never knew an exceptton but one, which prefented itielf during-a fog on.a winter day,. that proved un-- commenly warm), is it not reafonable to believe, that cold eleétrifies the atmofphere fofitzvely? and,_if fo, may not one be led to imagine, that heat electrifes it.negatively?. But this L only offer as a conjecture, not being able to advance any. thing decifive on the fabjedt, and kn owing that one fort of eleétricity may (Eas often. [ x40 ] often be productive of the other, as is plain from Dr, ~ Franklin's experiments. : If cold electrifies the air fc/itzvely in this climate {which feems extremely probable), may it not elec- trify it megatzvely at and about the place of our anti- podes? Does not a confideration of the effects dif- covered in the Tourmalin favour this furmife? The electricity of the air, in frofty, foggy or mifly weather, 1s not ftrong enough to yield any {park, even by infulating a fharp pointed wire in it, which, however, attracts very light bodies at a {mall diftance ; whilft, on the contrary, that of the clouds - generally affords confiderably {trong {parks. When a fog becomes very thick, the cork-balls approach; but when it returns to its former ftate, they open again at their firft diftance; and I have obferved that, when it rained in foggy weather, the balls clofed, and opened again on the fog’s appear- ance anew, after the rain had ceafed: there is, how- ever, a Certain degree of denfity neceflary in a fog, in order that the balls might exert their greateft di- vergency. Moit, if not all, fogs partake of a fmell much like that of an excited glafs tube, and, indeed, fo does the common air very frequently. As fogs fometimes appear in a very moift ftate of the air, I was for fome time at a lofs to account on what principle they could retain their eleétricity ; but having at length remarked, that electrified bodies, infulated with fealing-wax, preferved their electricity for a time in very damp air, I concluded that moif- ture is but a very flow conductor. Having, \ omar] “Having, on the contrary, obferved that bodiés, “infulated with dried filk, had loft their eleCtricity in a very fhort time, I attempted to render it a non- conductor, by having varnifhed it over with oil of turpentine, balfam of fulphur, and fuch like, but did not fucceed ; for filks fo treated foon became a conductor, and increafed confiderably in weight, if the air happened not to be very * dry; fo much indeed, that I think ordinary filk, from its power of abforbing moifture from the air, may well ferve as an occafional hygrometer, either by being put into a balance, or by having an electrified bey infulated with it. When the denfity of fogs, floating near the earth, increafes confiderably, the balls always approach ; but when they are fituated high in air, the reverfe generally happens. I had an opportunity of remark- ing a ftruggle between breezes from the north-weft and fouth-eaft at the fame time, tn which the one. feemed fometimes to prevail, and afterwards the other. This contention was fucceeded by a fmoaky hazinefs, which, like a fog, occafioned the balls to open: as the hazinefs + thickened, they opened * Even glafs attracts moifture to its furface, which makes it a conductor of electricity, and, confequently, not fo convenient as fealing-wax. _+ An ele@trical body, when contra&ted in its dimenfion, will have its electricity increafed, as appears by Dr. Franklin’s cu- © rious experiment with the chain and filver can. I alfo have dif- covered, from repeated trials, that a piece of flannel, filk, &c. excited, and fuddenly twifted, not only ftruck at a greater di- ftance than before, but fometimes emitted pencils of fire into the air. May we not hence infer why the electricity of vapour, &c. (wken not in contact with the earth) increafes by condenfa- tion? e wider, ae wider, and {till wider when it diffolved into rain; but their repelling power became greatelt i 1D propery as the drops increafed. The electrometer placed out from a garret window: (p. 138.), has been frequently ufeful to me, in de-. termining the nature of an approaching cloud, whofe- eleatricity, although generally ftrong, was for the moft part uncertain, having been fometimes po/fitive,. and at other times negative. But, as the wind or rain, were frequent impediments to the accuracy of my — experiments, the following methods of making obfer-- vations, with fuccefs, under fhelter, occurred to me.. I have fometimes ftood, in an upper room, on a: cake of wax,. holding in my right hand, out at the. window, a long {lender piece of wood, round which: a wire projecting a few inches had been twifted, and. in my left hand an electrometer: an affiftant had ex-. cited glafs or wax. in readineds. : At other: times, I have made ufe of a tapering. tube of tin, twenty feet long, ending in a points. the- greateit part of it ftood out high in the air, and the thick end, from which an eleftrometer hung, was fapported infide. the: window, fometimes with filk. cords, and at other times-with trong fticks of, fealing- wax,, fuftained at either end by Roe of iron-Wire. . By either of thefe means:I have. often: difcovered,, that what feemed.to.meafingle cloud, produced, in, its pafling over, feveral fucceflive changes, from fo-- fitive to negateve, and from negative. to pofitive elec-- tricity, the balls coming together each time, and re-. maining in contact a fem feconds, before they ree. pelled each other again... [ 143 ] ‘The permanence of either kind of eletricity it. the clouds, or the length of time in which neither can be difcovered, is uncertain; fometimes the fame ele€tricity has returned, and at other times has been fucceeded by the contrary ; whilft either generally came on, and went off gradually. But changes were | often made, very fuddenly, by a flath of lightning, efpecially if the thunder-ftorm happened to be in the zenith. A branch of it, over-head, has fre- quently occafioned ftronger eleétricity than I could difcover, when the greateft part of the fky had been overcafts which, perhaps, might be accounted for, from this confideration, that one kind of electricity adting alone, muft exert more powerful effects than when counteracted by the other. I once obferved in a thunder-{ftorm, during which I faw no lightning, that the balls, which hung from the tin tube, repelled and attracted each other, very rapidly, for the {pace of ten or twelve feconds ; at the fame time, Mr, Canton’s electrometer, which I held at fuch a diftance from the tube, as to have its balls opened to the diftance of an inch, continued quiet. in that ftate, and were not affected convulfively like the others. Hence I imagined, that the fame kind. of electricity went off, and came on, without being changed 7 contrarium; for when that circumftance happened, they were very evidently affected in the fame manner. And here I mufit obferve, that I have found it more eafy to difcover the kind of electricity prefent in the tube, by approaching ex- cited wax to the balls of an elcétrometer, which I held at a proper diftance from the tube, than by ap- plying it near the balls which hung from the ree or rat for they, in the general, diverged fo much, that F found-it very difficult to have in readinefs a {malt tube of glafs, or wax fufficiently excited to affect. them. It has fometimes happened: that the- balls of the tin tube, &c. perfectly at reft, have, in confequence- of a flafh of lightning, fuddenly repelled each other, and immediately after clofed. As this circumftance — has frequently happened, when the air was in a. damp ftate, I have fometimes imagined’ that the equilibrium: between the earth and lower clouds had been quickly reftored, on receiving the electricity of the higher ones; and, at other times, have fuppofed. that it might be owing to the lateral effect of the explofion. If two or more perfons, at a fufficient diftance fram each other, would-correfpond, by fignals, viz. a red flag for pofitive, and-a blue: one for negative. electricity, we fhould probably obtain, in due time, nore fatisfactory certainty with regard to the electricity of the clouds, thunder, &c. than. has hitherto: been: given, or is, perhaps, poffible for any one man to acquire, without the aid of wires or chains, produced, from different apparatuffes, placed at- different: diftances from each. other.. Mr. f 145] Mr. Ronayne having received the foligwitip Letter from Mr. Henly, which corroborates and con- firms the obfervations mentioned in his paper, it was thought proper to print them together in- this volume. Odtober 16, 1471; E patt ¢, P. M. a fog (not very thick), foon after its ap- — Pete nc ftrongly electrical, The balls open Zor Z inch A, [See Tab. VIII], and clofe at the en of pycicd wax, When brought within 10 inches of them B: if the wax is brought within 3 or 4 inches, they diverge again, in confequence thereof C: as the wax is withdrawn, they converge again, D, till it gets beyond the diffance of its in- fluence, when they begin to diverge again; and, as the wax is withdrawn ftill farther, they continue to open, in confequence of the electricity in the fog, till they reach their original diftance from each other E. There is very little difturbance by the wind, and the little there 1s, only wafts them in a {mall degree, but they keep feparate. If they are held near the tiling, or brick-work, of a neighbouring houfe, they clofe, F; but begin to diverge again, at the diftance of 3 or 4 feet from it, G3; and their di- vergence increafes, as they recede from the building, till they feparate 4 or 2 inch, as at firft, H. ; Vor. LXII. ce Memo- [ 146 ] Me won anova Oober 3, 1771, I tried the electricity of a thick fog, and (in at leaft twenty different trials) found the balls feparated from 4 to 3 inch diftance. Whenever I brought them near the building, or approached them with a ftick of excited wax, they clofed ; and opened again, on removing them. 3 W. Henly. | XIX. Ob- Tey ne of i om Sit ohei neste s LeHele eheretay eave Pike thee te AEB tet es He tees +4045 Ifetrier Seta) *i7, Sheen pie 4] srt GetheSs aes is ae te ahaa pei tet Mahar te olga leerant ie Hh ee stititer BL * bhi te stats Pete ese ees hie peladecebein aslirees enetleds eishinit, es grits Sees tases as itt? yes ath 2 ba) = it Teheha) tn dees: Tait biecnson ets la thee tote Tt viSieiaesl oir apstaare eaiteest et Bitte tete tas: feta tant et Nv ite iaigan a: a FAS tegemerarctcs Ny Pears PEER! MY ities Rin tecgaere es srvenes ers SEs Siete iste aeotkentesee) eherethian ee Maleis tee riees H + ahestayy ots .. Seeterett thbebes sth es ” thet sept hts bhen RUTUItP or re stink at iecr ai os opus aatraittabas +t ' ies etaleete! Fethiye + H< wr ibete TELE rece reuse isietad Isa Ss chluabib leeds itideniener sis cite ey ; ry : fieuaie is Shsace acts te Pood goes bleeceisdebetay Nabele ssh eee Midselecotbebaais lesbhoas teks thee ate vey Prise ately L oemeemeaas pats Sie hay. +h ehetats Fismeaeg vhilelise Pu btin ie itseune, 4€ 14:15 pp, MEE ace 9 Suniiet & ; «labo leveliegs shy Ueeae Meh edeie be el ezvener arr jp leitic iste feitiviehiweiss

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