ADVERTISEMENT.

M. JOHN Hyacinth De Magellan, in London, having fometime ago offered, as a donation, to the American Philofophical Society, held at Philadelphia for promoting ufeful knowledge, the fum of two hundred guineas, to be by them vefted in a fecure and permanent fund, to the end that the intereft arifing therefrom should be annually disposed of in premiums, to be adjudged by the fociety, to the author of the best difcovery, or most useful invention, relating to navigation, aftronomy, or natural philosophy (mere natural history only excepted) and the society having accepted of the above donation, hereby publish the conditions, prefcibed by the donor, and agreed to by the fociety, upon which the faid annual premiums will be awarded.

i. The candidate fhall fend his discovery, invention or improvement, addreffed to the President, or one of the Vice Presidents of the fociety, free of postage or other charges; and shall distinguish his performance by fome motto, device or other fignature, at his pleasure. Together with his discovery, invention or improvement, he shall also send a sealed letter, containing the fame motto, device or fignature, and fubfcribed with the real name, and place of refidence of the author.

2. Perfons of any nation, fect or denomination whatever, shall be admitted as candidates for this premium.

3. No discovery, invention or improvement shall be entitled to this premium which hath been already published, or for which the author hath been publicly rewarded elfe where.

4. The candidate fhall communicate his discovery, invention or improvement, either in the English, French, German or Latin language.

5. All fuch communications shall be publicly read, or exhibited to the fociety, at fome stated meeting, not lefs than one month previous to the day of adjudication, and fhall at all times be open to the inspection of fuch members as fhall defire it. But no member fhall carry home with him the communication, defcription or model, except the officer to whom it shall be intrufted; nor fhall fuch officer part with the fame out of his cuftody, without a special order of the fociety for that purpofe,

6. The

6. The fociety having previously referred the feveral communications, from candidates for the premium then depending, to the confideration of the twelve counsellors and other officers of the fociety, and having received their report thereon, fhall, at one of their ftated meetings, in the month of December, annually, after the expiration of this current year (of the time and place, together with the particular occafion of which meeting, due notice fhall be previously given, by public advertise- -ment) proceed to the final adjudication of the faid premium: and after due confideration had, a vote fhall first be taken on this queftion, viz. Whether any of the communications then under infpection be worthy of the propofed premium? If this question be determined in the negative, the whole business shall be deferred till another year: but if in the affirmative, the fociety fhall proceed to determine by ballot, given by the members at large, the difcovery, invention or improvement, most useful and worthy; and that discovery, invention or improvement, which fhall be found to have a majority of concurring votes in its favour shall be fuccefsful; and then, and not till then, the fealed letter, accompanying the crowned performance, fhall be opened, and the name of the author announced as the perfon entitled to the faid premium.

7. No member of the fociety who is a candidate for the premium then depending or who hath not previously declared to the fociety, either by word or writing, that he has confidered and weighed, according to the best of his judgment, the comparative merits of the feveral claims. then under confideration, fhall fit in judgment or give his vote in award- ing the faid premium.

8. A full account of the crowned fubject fhall be published by the fociety as foon as may be, after the adjudication, either in a feparate publication, or in the next fucceeding volume of their tranfactions, or in both.

9. The unfuccefsful performances fhall remain under confideration, and their authors be confidered as candidates for the premium, for five years, next fucceeding the time of their prefentment, except fuch performances as their authors may, in the mean time, think fit to withdraw. And the fociety fhall, annually, publish an abstract of the titles, object or fubject matter of the communications fo under confideration; fuch only excepted as the fociety fhall think not worthy of public notice. 10. The letters containing the names of authors whose performances

shall :

hall be rejected, or which shall be found unsuccessful, after a tryal of five years, shall be burnt before the fociety, without breaking the seals.

II. In cafe there fhould be a failure, in any year, of any communi,cation worthy of the propofed premium, there will then be two premiums to be awarded in the next year. But no accumulation of premiums fhall entitle an author to more than one premium for any one discovery, invention or improvement.

12. The premium fhall confift of an oval plate of folid standard gold, of the value of ten guineas, on one fide thereof fhall be neatly engraved a fhort Latin motto, fuited to the occafion, together with the words The premium of John Hyacinth De Magellan, of London, established in the year 1786. And on the other fide of the plate fhall be engraved these words. Awarded by the A. P. S.

1

difcovery ofA. D.

for the

And the feal of the fociety fhall be annexed to the medal by a ribbon paffing through a small hole at the upper end of the plate.

The following communications from candidates for the Magellanic annual premium, remain under confideration.

1. An effay on warming rooms. Motto, Cuique eveniat femper prout meruit. Read May 20, 1791.

The author proposes, as an addition to the Franklinian fire-place, or open ftove, that the fresh air neceffary to feed the fire, be admitted from without, through tin pipes, placed under the floor, and rifing up through the hearth at one side of the ftove, where they communicate with iron pipes paffing thro' the fire as a grate. These iron pipes again communicate with tin ones, extending up behind the wainfcot, nearly to the ceiling, where the air, now heated by passing through the fire, is fuffered to escape into the room. By this contrivance, the inconvenience arifing from the rufhing in of cold air from without, through every crevice and aperture where it can find a paffage, will, it is alledged, be effectually prevented, and the room keep warm with much lefs expence of fuel than in the common way.

2. An attempt to prove that the generally received opinion, that fteel fprings acquire an increase of strength or power by cold weather, and lofe power by warm weather, is erroneous-Signature ScrupulousRead November 4, 1791.

The

The writer endeavours to establish this pofition, both from theory and experiment. Heat expands and cold contracts a fpring, or any other piece of metal proportionally, in all its dimenfions; and therefore, while cold makes a fpring fhorter, and on that account would increase its power, it alfo makes it both narrower and thinner, and on this account would diminish its power, in the fame proportion; accordingly, by experiment, he found that a spring of twelve inches long, made faft at one end, and having a weight fufpended from the other, did not füffer the weight visibly to descend, upon being heated even to fuch a degree as to evaporate a drop of water applied to it. If the above pofition be true, the thermometer-curb, applied to Harrison's and other time-picces, instead of being an advantage, muft be directly the contrary.

3. A defcription, accompanying a model of a machine, which the author calls an Elevator-Motto, Nititur in ardua Virtus-Read December 2, 1791.

The machine is a compound of perpendicular shafts, fo connected by grooves, ropes and puliies, that each moves its inmate, and thus all rife together.

"This machine," the author obferves, "may be applied to many important ufes-A person of common weight may ascend an hundred feet upon a frame of light construction to gain a rocky precipice, to enjoy a fine profpect, to reconnoitre the encampment of an enemy, and to discover land at fea.-Dispatch in loading and unloading, or any quick alternate motion, is well performed by the multiple motion of this elevator."

4. A defcription with a model of a mechanical apparatus for regulating and governing the fails of a veffel at fea-Signature I. S. S.— Read November 2, 1792.

The author proposes, that each fail be placed within a large frame turning round on pivots at the top and bottom. At the extremity of the upper pivot or gudgeon is fixed a cog or fpur wheel, which is turned by another wheel having half the number of teeth, and this fupports a large vane, about one fifth of the fize of the fail, which is turned round with the wind. By this means the angular motion of the fail will be but half that of the vane. Hence if the wind when directly a-ftern, be at right angles with the plane of the fail, a fide wind would ftrike the plane of the fail at an angle of forty-five degrees, and a wind four points before the beam, would strike the fail at an angle of two points and an half; and thus, it is presumed, that the mere action of the wind upon the Ааа

vane,

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vane, would always turn the fails into their proper pofition, without any manual operation whatever. He also proposes a method of furling the fails by means of rollers, to be worked with cranks.

5. An improvement in the art of guaging. Signature W.-Read November 16, 1792.

The author points out various fources of error in the present practice of guaging, particularly taking the dimensions outfide of the cafk. He gives a drawing and description of an instrument for taking the neceffary dimenfions, viz. The length, head-diameter, bung-diameter, and a middle diameter between the head and bung, all infide of the cafk; and by means of a table which he has fubjoined, fhews how to compute the contents of any cask from these dimensions, with the greatest ease and

accuracy.

Befides the above communications, an effay on the caufes of the tides. has been received, but not being within the limited time, was not brought under confideration at the last adjudication.

Several other pieces have been before the Society, but as their time of probation (five years) will expire before the next adjudication, in December 1793, they are of courfe decifively unfuccefsful, and need not

be noticed.