Transcriber’s Note

Variable spelling and hyphenation have been retained. Minor punctuation inconsistencies have been silently repaired. [The Errata] of the original edition have been corrected. Other changes made can be found [at the end of the book].

PHILOSOPHICAL TRANSACTIONS, GIVING SOME ACCOUNT OF THE Present Undertakings, Studies, and Labours, OF THE INGENIOUS, IN MANY Considerable Parts of the WORLD.

PHILOSOPHICAL
TRANSACTIONS,
GIVING SOME
ACCOUNT
OF THE
Present Undertakings, Studies, and Labours,
OF THE
INGENIOUS,
IN MANY
Considerable Parts of the WORLD.

VOL. L. Part II. For the Year 1758.

LONDON:

Printed for L. Davis and C. Reymers,
Printers to the Royal Society,
against Gray’s-Inn Gate, in Holbourn.

M.DCC.LIX.

THE
CONTENTS
TO
Part II. Volume L.

LIX.AN Account of the Effects of Electricity in paralytic Cases. In a Letter to John Pringle, M. D. F.R.S. from Benjamin Franklin, Esq; F.R.S.p. [481].
LX.Observations on the late Comet in September and October 1757; made at the Hague by Mr. D. Klinkenberg: In a Letter to the Rev. James Bradley, D. D. Astronomer Royal, and F.R.S. and Member of the Royal Academy of Sciences at Paris. Translated from the Low Dutch.p. [483].
LXI.Remarks on the different Temperature of the Air at Edystone, from that observed at Plymouth, between the 7th and 14th of July 1757. By Mr. John Smeaton, F.R.S.p. [488].
LXII.An Account of the Earthquake felt in the Island of Sumatra, in the East Indies, in November and December 1756. In a Letter from Mr. Perry to the Rev. Dr. Stukeley, dated at Fort Marlborough, in the Island of Sumatra, Feb. 20. 1757. Communicated by the Rev. Wm. Stukeley, M. D. F.R.S.p. [491].
LXIII.Concerning the Fall of Water under Bridges. By Mr. J. Robertson, F.R.S.p. [492].
LXIV.An Account of the Earthquake in the West Parts of Cornwall, July 15th 1757. By the Rev. William Borlase, M. A. F.R.S. Communicated by the Rev. Charles Lyttelton, LL. D. Dean of Exeter, F.R.S.p. [499].
LXV.Some Observations upon the Sleep of Plants; and an Account of that Faculty, which Linnæus calls Vigiliæ Florum; with an Enumeration of several Plants, which are subject to that Law. Communicated to Wm. Watson, M. D. F.R.S. by Mr. Richard Pulteney of Leicester.p. [506].
LXVI.An Account of the Case of a Boy troubled with convulsive Fits cured by the Discharge of Worms. By the Rev. Richard Oram, M. A. Chaplain to the Lord Bishop of Ely.p. [518].
An Account of the same Subject, in a Letter from Mr. John Gaze, of Walket, in the County of Norfolk, to Mr. Wm. Arderon, F.R.S. Communicated by Mr. Henry Baker, F.R.S.p. [521].
LXVII.An Account of the extraordinary Heat of the Weather in July 1757, and of the Effects of it. In a Letter from John Huxham, M. D. F.R.S. to Wm. Watson, M. D. F.R.S. p. [523].
LXVIII.An Account of the fossile Thigh-bone of a large Animal, dug up at Stonesfield, near Woodstock, in Oxfordshire. In a Letter to Mr. Peter Collinson, F.R.S. from Mr. Joshua Platt.p. [524].
LXIX.A Discourse of the Usefulness of Inoculation of the horned Cattle to prevent the contagious Distemper among them. In a Letter to the Right Hon. George Earl of Macclesfield, P. R. S. from Daniel Peter Layard, M. D. F.R.S.p. [528].
LXX.Trigonometry abridged. By the Rev. Patrick Murdoch, A. M. F.R.S.p. [538].
LXXI.An Account of Two extraordinary Cases of Gall-Stones. By James Johnstone, M. D. of Kidderminster. Communicated by the Rev. Charles Lyttelton, LL. D. Dean of Exeter. p. [543].
LXXII.A remarkable Case of Cohesions of all the intestines, &c. in a Man of about Thirty-four years of Age who died sometime last Summer, and afterwards fell under the Inspection of Mr. Nicholas Jenty. p. [550].
LXXIII.Of the best Form of Geographical Maps. By the Rev. Patrick Murdoch, M. A. F.R.S.p. [553].
LXXIV.A short Dissertation on Maps and Charts: In a Letter to the Rev. Thomas Birch, D. D. and Sec. R. S. By Mr. William Mountaine, F.R.S.p. [563].
LXXV.Cases of the remarkable Effects of Blisters in lessening the Quickness of the Pulse in Coughs, attended with Infarction of the Lungs and Fever: By Robert Whytt, M. D. F.R.S. Fellow of the Royal College of Physicians, and Professor of Medicine in the University of Edinburgh.p. [569].
LXXVI.A remarkable Instance of Four rough Stones, that were discovered in an human urinary Bladder, contrary to the received Opinion; and successfully extracted by the lateral Method of Cutting for the Stone. By Mr. Joseph Warner, F.R.S. and Surgeon to Guy’s-Hospital.p. [579].
LXXVII.Observations on the Limax non cochleata Purpuram ferens, The naked Snail producing Purple. By John Andrew Peyssonel, M. D. F.R.S. Translated from the French. p. [585].
LXXVIII.New Observations upon the Worms that form Sponges. By John Andrew Peyssonel, M. D. F.R.S. Translated from the French.p. [590].
LXXIX.Account of an Experiment, by which it appears, that Salt of Steel does not enter the Lacteal Vessels; with Remarks. In a Letter to the Rev. Thomas Birch, D. D. Secret. R. S. By Edward Wright, M. D.p. [594].
LXXX.A Dissertation on the Antiquity of Glass in Windows. In a Letter to the Rev. Tho. Birch, D. D. Secret. R. S. By the Rev. John Nixon, M. A. F.R.S.p. [601].
LXXXI.An Account of an extraordinary Case of the Efficacy of the Bark in the Delirium of a Fever. By Nicˢ. Munckley, M. D. Physician to Guy’s-Hospital, and F.R.S.p. [609].
LXXXII.An Account of an Earthquake felt at Lingfield in Surrey, and Edenbridge in Kent, on the 24th of January 1758. By James Burrow, Esq; R. S. V. P.p. [614].
LXXXIII.An Account of the Case of the First Joint of a Thumb torn off, with the Flexor Tendon in its whole Extent torn out. By Robert Home, late Surgeon to the Thirtieth Regiment of Foot, and Surgeon at Kingston upon Hull. In a Letter to John Pringle, M. D. F.R.S.p. [617].
LXXXIV.An Account of the late Discoveries of Antiquities at Herculaneum, and of an Earthquake there; in a Letter from Camillo Paderni, Keeper of the Museum at Herculaneum, and F.R.S. to Tho. Hollis, Esq; F.R.S. dated Portici, Feb. 1. 1758. p. [619].
LXXXV.A further Attempt to facilitate the Resolution of Isoperimetrical Problems. By Mr. Thomas Simpson, F.R.S.p. [623].
LXXXVI.Observations on the Alga Marina latifolia; The Sea Alga with broad Leaves. By John Andrew Peyssonel, M. D. F.R.S. Translated from the French.p. [631].
LXXXVII.An Account of the distilling Water fresh from Sea-Water by Wood-Ashes. By Capt. William Chapman: In a Letter to John Fothergill, M. D.p. [635].
LXXXVIII.Observatio Eclipsis Lunaris facta Matriti a Pª. Joanne Wendlingen, Societatis Jesu, in Regali Observatorio Collegii Imperialis ejusdem Societatis, Die 30 Julii 1757.p. [640].
Observatio Eclipsis Lunaris, facta ab eodem, eodem modo, eodem loco, iisdemque instrumentis, Die 24 Januar. Anni 1758.p. [642].
LXXXIX.Observations upon a slight Earthquake, tho’ very particular, which may lead to the Knowlege of the Cause of great and violent ones, that ravage whole Countries, and overturn Cities. By John Andrew Peyssonel, M. D. F.R.S. Translated from the French.p. [645].
XC.A Catalogue of the Fifty Plants from Chelsea Garden, presented to the Royal Society by the worshipful Company of Apothecaries, for the Year 1757, pursuant to the Direction of Sir Hans Sloane, Baronet, Med. Reg. & Soc. Reg. nuper Præses, by John Wilmer, M. D. clariss. Societatis Pharmaceut. Lond. Socius, Hort. Chelsean. Præfectus & Prælector Botanic.p. [648].
XCI.An Historical Memoir concerning a Genus of Plants called Lichen by Michelli, Haller, and Linnæus; and comprehended by Dillenius under the Terms Usnea, Coralloides, and Lichenoides: Tending principally to illustrate their several Uses. Communicated by William Watson, M. D. F.R.S.p. [652].
XCII.An Account of the fossil Bones of an Allegator, found on the Sea-shore, near Whitby in Yorkshire: In a Letter to John Fothergill, M. D. from Capt. William Chapman.p. [688].
XCIII.De rariori quadam Orthoceratitis Specie, in Suecia reperta, tractatus: in literis a Nicholao de Himsel, M. D. Riga Livono, ad Gul. Watson, M. D. R. S. S.p. [692].
XCIV.A further Account of the Effects of Electricity in the Cure of some Diseases: In a Letter from Mr. Patrick Brydone to Dr. Robert Whytt, Professor of Medicine in the University of Edinburgh, and F.R.S.p. [695].
XCV.An Account of the Black Assize at Oxford, from the Register of Merton College in that University. Communicated by John Ward, LL. D. With some additional Remarks.p. [699].
XCVI.A Description of the Plan of Peking, the Capital of China; sent to the Royal Society by Father Gaubil, è Societate Jesu. Translated from the French.p. [704].
XCVII.An Attempt to improve the Manner of working the Ventilators by the Help of the Fire-Engine. In a Letter to Tho. Birch, D. D. Secret. R. S. from Keane Fitz-Gerald, Esq; F.R.S.p. [727].
XCVIII.An Account of some Experiments concerning the different Refrangibility of Light. By Mr. John Dollond. With a Letter from James Short, M. A. F.R.S. Acad. Reg. Suec. Soc.p. [733].
XCIX.An Account of some extraordinary Effects arising from Convulsions; being Part of a Letter to John Huxham, M. D. and F.R.S. from William Watson, M. D. R. S. S.p. [743].
C.An Account of an extraordinary Storm of Hail in Virginia. By Francis Fauquier, Esq; Lieutenant Governor of Virginia, and F.R.S. Communicated by William Fauquier, Esq; F.R.S.p. [746].
CI.An Account of an extraordinary Case of a diseased Eye: In a Letter to Matthew Maty, M. D. F.R.S. By Daniel Peter Layard, M. D. F.R.S.p. [747].
CII.An Account of the Heat of the Weather in Georgia: In a Letter from his Excellency Henry Ellis, Esq; Governor of Georgia, and F.R.S. to John Ellis, Esq; F.R.S.p. [754].
CIII.The Invention of a General Method for determining the Sum of every 2d, 3d, 4th, or 5th, &c. Term of a Series, taken in order, the Sum of the whole Series being known. By Thomas Simpson, F.R.S.p. [757].
CIV.Observatio Eclipsis Lunæ Die 30 Julii 1757. habita Olissipone à Joanne Chevalier, Congregationis Oratorii Presbytero, è Regiâ Londinensi Societate. Communicated by Jacob de Castro Sarmiento, M. D. F.R.S.p. [769].
CV.Singular Observations upon the Manchenille Apple. By John Andrew Peyssonel, M. D. F.R.S. Translated from the French.p. [772].
CVI.Abstract of a Letter from Mr. William Arderon, F.R.S. to Mr. Henry Baker, F.R.S. on the giving Magnetism and Polarity to Brass. Communicated by Mr. Baker.p. [774].
CVII.An Account of the Sea Polypus, by Mr. Henry Baker, F.R.S.p. [777].
CVIII.A Description of the fossil Skeleton of an Animal found in the Alum Rock near Whitby. By Mr. Wooller. Communicated by Charles Morton, M. D. F.R.S.p. [786].
CIX.A Dissertation on the Phœnician Numeral Characters antiently used at Sidon. In a Letter to the Rev. Tho. Birch, D. D. Secret. R. S. from the Rev. John Swinton, M. A. of Christ-Church, Oxon. F.R.S.p. [791].
CX.Of the Irregularities in the Motion of a Satellite arising from the Spheroidical Figure of its Primary Planet: In a Letter to the Rev. James Bradley, D. D. Astronomer Royal, F.R.S. and Member of the Royal Academy of Sciences at Paris; by Mr. Charles Walmesley, F.R.S. and Member of the Royal Academy of Sciences at Berlin, and of the Institute at Bologna.p. [809].
CXI.Some Observations on the History of the Norfolk Boy. By J. Wall, M. D. In a Letter to the Rev. Charles Lyttelton, LL. D. Dean of Exeter.p. [836].
CXII.Observations upon the Corona Solis Marina Americana; The American Sea-Sun-Crown. By John Andrew Peyssonel, M. D. F.R.S.p. [843].
CXIII.An Account of several rare Species of Barnacles. In a Letter to Mr. Isaac Romilly, F.R.S. from John Ellis, Esq; F.R.S.p. [845].
CXIV.A further Account of the poisonous Effects of the Oenanthe Aquatica Succo viroso crocante of Lobel, or Hemlock Dropwort. By W. Watson, M. D. F.R.S.p. [856].
CXV.Extract of a Letter to John Eaton Dodsworth, Esq; from Dr. George Forbes of Bermuda, relating to the Patella, or Limpet Fish, found there. p. [859].
CXVI.A Discourse on the Cinnamon, Cassia, or Canella. By Taylor White, Esq; F.R.S.p. [860].

LIX. An Account of the Effects of Electricity in paralytic Cases. In a Letter to John Pringle, M. D. F.R.S. from Benjamin Franklin, Esq; F.R.S.

SIR,

Read Jan. 12, 1758.

THE following is what I can at present recollect, relating to the effects of electricity in paralytic cases, which have fallen under my observation.

Some years since, when the news-papers made mention of great cures performed in Italy or Germany, by means of electricity, a number of paralytics were brought to me from different parts of Pensylvania, and the neighbouring provinces, to be electrised; which I did for them at their request. My method was, to place the patient first in a chair, on an electric stool, and draw a number of large strong sparks from all parts of the affected limb or side. Then I fully charged two six-gallon glass jars, each of which had about three square feet of surface coated; and I sent the united shock of these thro’ the affected limb or limbs; repeating the stroke commonly three times each day. The first thing observed was an immediate greater sensible warmth in the lame limbs, that had received the stroke, than in the others: and the next morning the patients usually related, that they had in the night felt a pricking sensation in the flesh of the paralytic limbs; and would sometimes shew a number of small red spots, which they supposed were occasioned by those prickings. The limbs too were found more capable of voluntary motion, and seemed to receive strength. A man, for instance, who could not the first day lift the lame hand from off his knee, would the next day raise it four or five inches, the third day higher; and on the fifth day was able, but with a feeble languid motion, to take off his hat. These appearances gave great spirits to the patients, and made them hope a perfect cure; but I do not remember, that I ever saw any amendment after the fifth day: which the patients perceiving, and finding the shocks pretty severe, they became discouraged, went home, and in a short time relapsed; so that I never knew any advantage from electricity in palsies, that was permanent. And how far the apparent temporary advantage might arise from the exercise in the patients journey, and coming daily to my house, or from the spirits given by the hope of success, enabling them to exert more strength in moving their limbs, I will not pretend to say.

Perhaps some permanent advantage might have been obtained, if the electric shocks had been accompanied with proper medicine and regimen, under the direction of a skilful physician. It may be, too, that a few great strokes, as given in my method, may not be so proper as many small ones; since, by the account from Scotland of a case, in which two hundred shocks from a phial were given daily, it seems, that a perfect cure has been made. As to any uncommon strength supposed to be in the machine used in that case, I imagine it could have no share in the effect produced; since the strength of the shock from charged glass is in proportion to the quantity of surface of the glass coated; so that my shocks from those large jars must have been much greater than any, that could be received from a phial held in the hand.

I am, with great respect,

SIR,
Your most obedient Servant,
R. Franklin.

London, Dec. 21, 1757.

LX. Observations on the late Comet in September and October 1757; made at the Hague by Mr. D. Klinkenberg: In a Letter to the Rev. James Bradley, D. D. Astronomer Royal, and F.R.S. and Member of the Royal Academy of Sciences at Paris. Translated from the Low Dutch.

SIR,

Read Jan. 12, 1758.

I Hope you will be pleased to excuse the liberty, which I take, of troubling you with my observations on the comet, which made its appearance here, and in other parts of Europe, in the months of September and October last; and which, according to the news-papers, was first observed the 11th September by Mr. Gartner, at Dorlkeurtz near Dresden; then, by me, on the 16th of the said Month, here in the Hague; and afterwards in different places. As I find, that you have observed the comet, I doubt not but that you have done it in the most accurate manner; and my great love for this science induces me to beg, that I may have the happiness of knowing some of your observations. My good friend Mr. Struyk at Amsterdam wrote me some time ago, that he intended to ask the same favour of you; but I have not since heard any further from him. I observed this comet from Septemb. 16th in the morning, until Octob. the 11th in the morning; and found its situations, according to my method, as follows:

Longit. Latit.
1757. ° ´ ° ´
Sept. 16. at4 h. ante mer. The comet in ♋ 10 15 with 10 10North.
17 — 3 — — — — —♋ 14 7 —— 9 38
18 — 3¾ — — — — — ♋ 18 10 —— 8 57
19 — 4 — — — — — ♋ 22 1 —— 8 17
22 — 2¾ — — — — — ♌ 3 46 —— 6 15
23 — 4 — — — — — ♌ 7 36 —— 5 24
25 — 4¼ — — — — — ♌ 14 50 —— 4 6
28 — 4 — — — — — ♌ 24 22 —— 1 41
Oct. 1 — 4¾ — — — — — ♍ 2 46 —— 0 12 South.
4 — 4½ — — — — — ♍ 9 45 —— 1 30
9 — 4½ — — — — — ♍ 20 20 —— 2 40
11 — 5 — — — — — ♍ 24 46 —— 3 9

But the two last observations will, in my opinion, differ the most; because, when I made them, I was in some doubt about the adjustment of my instruments; and the comet was then far advanced into the morning rays. I have, since the month of February last to the end of May, made sundry observations on fixed stars, with a telescope of 16 inches, made by Mr. Short; and with a pendulum clock, made after the manner of Mr. Graham, by Mr. Vryhthoff of this place. In the months of February and March, by a medium of eight observations, I found, that by the clock, the star Rigel, in every daily revolution, passed 4 min. 2⁴⁄₉ seconds of time earlier, in the telescope; and in the latter end of May I found, by six observations, (the clock not in the least changed or altered) on the star Spica Virginis, that that star, in every revolution, passed 4 min. 5¹⁄₂₀ sec. earlier, in the same telescope; which intervals differ pretty nearly 2⅗ seconds of time from one another. Whether this difference arises from any defect in the clock, or whether it proceeds from any small difference of velocity of the earth’s motion round its axis, I would have been very glad to have endeavoured to find out by farther inquiry, had not the death of Mr. S. Koenig intervened, and I thereby hindered from continuing my observations. The above observations were taken in the observatory of his illustrious Highness the minor Prince of Orange and Nassau, &c. &c. under the direction, and with the approbation of the aforesaid Mr. Koenig. After the death of that gentleman, I petitioned her Royal Highness the Princess Governess of these Provinces, &c. that I might have leave to continue my astronomical observations; but as yet I have not been able to obtain her Royal Highness’s permission: otherwise I would have observed this last comet with more exactness. Had I been able to pursue the above-mentioned observations, I would, for the greater certainty in regard to the pendulum, have made use of a farther precaution. By means of a stove, with the help of a thermometer, I would have endeavoured to have kept the room (in which the clock stood) in the winter, and at all times, in the same degree of heat it had at the time I made the observations in the summer. I would also have daily observed and noted the moon’s place, at the time of the observations. Tho’ this is but a slight observation of mine; yet I make no doubt, but that in case, by the different distances of the earth from the sun, and the different distances and situations of the moon with respect to the earth, and the respective effects produced by these causes, any inequality arises in the velocity of the diurnal motion of the earth on its axis, you (who have made the most sublime observations on the aberration of the fixed stars, and more than any mortal ever did before) must have discovered, and are well acquainted, with the same.

As my above-mentioned observations on the comet appeared too incorrect to undertake a calculation for the ascertaining of its path from the theory, I contented myself with effecting it by a construction. By this means I found, on a figure, whose globular or spherical diameter was 13½ Rhineland inches, as follows:

That the comet was in its perihelion the 21st of October, at two of the clock in the afternoon: the place of the perihelion 3 degrees in Leo. The comet’s distance in the perihelion from the sun was about 34 parts, whereof 100 make the mean distance between the sun and the earth. The inclination of the comet’s orbit with the ecliptic 13 degrees; and the southern latitude of the perihelion also 13 decrees: the ascending or north node ☊ 4⅓ degrees in Scorpio; and the comet’s motion direct, or according to the order of the signs of the zodiac. On this supposition I have, for some of the times of observations, estimated the apparent places of the comet, and found them as follows:

Long. Latit.
Sept. 18, at 3¾ ante merid. In ♋18¹⁄₁₂and9 deg. North.
19 — 4 — — — ♋ 22 —— 8⅖
22 — 2¾ — — — ♌ 3⅝ —— 6¼
23 — 4 — — — ♌ 7⅗ —— 5½
25 — 4¼ — — — ♌ 14⅔ —— 4
28 — 4 — — — ♌ 24⅓ —— 1¾
Oct. 4 — 4½ — — — ♍ 9⅓ —— 2 —— South.
9 — 4¾ — — — ♍ 19⅔ —— 3⅖
11 — 5 — — — ♍ 23⅛ —— 3⅘

The observations, which I have taken, to ground the measurement on, are those of the 16th and 23d of September, and of the 1st of October. It appears very evident, not only from this rough calculation, but every other circumstance of this comet, that it is not the same with that in the year 1682: which, on certain accounts, is very desirable to be known; for both here, and in other parts of the Netherlands, there have been some people, who have published mere conjectures; and have ventured (very minutely and exactly, as they pretended) about the time that this comet first made its appearance, to predict the return of the comet of the year 1682. But by the above, the weakness of their pretensions is very evident to all the world: whereas, if this had proved to be the expected comet, they would have assumed to themselves much undue praise, and have pretended to knowlege even superior to the every-where much celebrated Newton and Halley.

It appears also probable to me, that this comet is none of those already calculated, or brought upon a list, by Messieurs Halley and Struyk. It is somewhat remarkable, that the line of the nodes is almost at right angles with the long axis of the ellipsis; which corresponds nearly with the comets of the years 1580, 1683, and 1686: but those had their perihelions northward of the ecliptic; whereas the perihelion of the last, which we have lately seen, was to the southward of the ecliptic.

I have the honour to subscribe myself, with the most perfect esteem for you, and your sublime studies, very respectfully,

SIR,
Your very humble and obedient Servant,
D. Klinkenberg.

Hague, 13th Dec. 1757.

LXI. Remarks on the different Temperature of the Air at Edystone, from that observed at Plymouth, between the 7th and 14th of July 1757. By Mr. John Smeaton, F.R.S.

SIR,

Read Jan. 12, 1758.

ON the reading of Dr. Huxham’s letter at the last meeting, some observations occurred to me, concerning the different temperature of the air, which I had observed at the Edystone, from what had been observed by the Doctor at Plymouth, between the 7th and 14th of July last: which having been desired by some members to be put into writing, I beg leave to trouble you with the following.

Edystone is distant from Plymouth about 16 miles, and without the head-lands of the Sound about 11.

The 7th and 8th were not remarkable at Edystone for heat or cold; the weather was very moderate, with a light breeze at east; which allowed us to work upon the rock both days, when the tide served.

About midnight, between the 8th and 9th, the wind being then fresh at east, it was remarkably cold for the season, as I had more particular occasion to observe, on account of a ship that was cast away upon the rocks. The wind continued cold the 9th all day; which was complained of by some of the shipwrecked seamen, who had not time to save their cloaths; and so fresh at east, as prevented our going near the rocks, or the wreck; and so continued till Sunday the 10th; when, seeing no prospect of a sudden alteration of weather, I returned to Plymouth in a sailing boat, wrapped up in my thick coat. As soon as we got within the headlands, I could perceive the wind to blow considerably warmer; but not so warm as to make my great coat uneasy. Having had a quick passage, in this manner I went home, to the great astonishment of the family to see me so wrapped up, when they were complaining of the excessive heat: and indeed, it was not long before I had reason to join in their opinion.

This heat I experienced till Tuesday the 12th, when I again went off to sea, where I found the air very temperate, rather cool than warm; and so continued till Thursday the 14th.

In my journal for Wednesday the 13th I find the following remarks, viz. “This evening’s tide” (from 6 A. till 12 A.) “the wind at east, but moderate, with frequent flashes of lightning to the southward. Soon after we got on board the store-vessel, a squall of wind arose from the south-west on a sudden, and continued for about a minute; part of which time it blew so hard, we expected the masts to go by the board: after which it was perfectly calm, and presently after a breeze returned from the east.”

And in the journal of the 14th is entered, “This morning’s tide” (viz. from 1 M. to 1 A.) “the air and sea quite calm.”

Hence it appears, how different the temper of the air may be in a small distance; and to what small spaces squalls of wind are sometimes confined.

It may not be amiss further to observe upon this head, that once, in returning from Edystone, having got within about two miles of the Ramhead, we were becalmed; and here we rolled about for at least four hours; and yet at the same time saw vessels, not above a league from us, going out of Plymouth Sound with a fresh of wind, whose direction was towards us, as we could observe from the trim of their sails; and as we ourselves experienced, after we got into it by tacking and rowing.

I am, Sir,

Your most humble Servant,
J. Smeaton.

Furnival’s-Inn Court, 12th Jan. 1758.

LXII. An Account of the Earthquake felt in the Island of Sumatra, in the East-Indies, in November and December 1756. In a Letter from Mr. Perry to the Rev. Dr. Stukeley, dated at Fort Marlborough, in the Island of Sumatra, Feb. 20. 1757. Communicated by the Rev. Wm. Stukeley, M. D. F.R.S.

Read Jan. 12, 1758.

THE earthquake at Lisbon, which you gave me an account of, was certainly the most awful tremendous calamity, that has ever happened in the world. Its effects are extremely wonderful and amazing; and it seems, as you observe, to have been felt in all parts of the globe. On the 3d day of the same month the earthquake of Lisbon happened, I felt at Manna[1] a violent shock myself; and from that time to the 3d of December following I felt no less than twelve different shocks, all which I took an exact account of in my pocket-bock. Since which we have had two very severe earthquakes, felt, we believe, throughout this island[2]. The walls of[3] Cumberland-house[4] were greatly damaged by them. Salop-house[4], my own (formerly Mr. Massey’s), the houses of Laye[5] and Manna, were all cracked by them; and the works at the sugar-plantation[6] received considerable damage. The ground opened near the qualloe[7] at Bencoolen, and up the River in several places; and there issued therefrom sulphureous earth, and large quantities of water, sending forth a most intolerable stench. Poblo Point[8] was much cracked at the same time; and some doosoons[9] in-land at Manna were destroyed, and many people in them.

These are all the ill effects, that have come to our knowlege; but, it is reasonable to suppose, not all the damage, that has happened upon the island.

LXIII. Concerning the Fall of Water under Bridges. By Mr. J. Robertson, F.R.S.

Read Jan. 19, 1758.

SOME time before the year 1740, the problem about the fall of water, occasioned by the piers of bridges built across a river, was much talked of at London, on account of the fall that it was supposed would be at the new bridge to be built at Westminster. In Mr. Hawksmore’s and Mr. Labelye’s pamphlets, the former published in 1736, and the latter in 1739, the result of Mr. Labelye’s computations was given: but neither the investigation of the problem, nor any rules, were at that time exhibited to the public.

In the year 1742 was published Gardiner’s edition of Vlacq’s Tables; in which, among the examples there prefixed to shew some of the uses of those tables drawn up by the late William Jones, Esq; there are two examples, one shewing how to compute the fall of water at London-bridge, and the other applied to Westminster-bridge: but that excellent mathematician’s investigation of the rule, by which those examples were wrought, was not printed, altho’ he communicated to several of his friends copies thereof. Since that time, it seems as if the problem had in general been forgot, as it has not made its appearance, to my knowlege, in any of the subsequent publications. As it is a problem somewhat curious, tho’ not difficult, and its solution not generally known (having seen four different solutions, one of them very imperfect, extracted from the private books of an office in one of the departments of engineering in a neighbouring nation), I thought it might give some entertainment to the curious in these matters, if the whole process were published. In the following investigation, much the same with Mr. Jones’s, as the demonstrations of the principles therein used appeared to be wanting, they are here attempted to be supplied.