Cy" 300) ) 
The writer endeavours to eftablith this poftion, both from theory 
and experiment.— Heat expands and cold contracts a fpring, or any 
other piece of metal proportionally, inallits dimenfions; and therefore, 
while cold makes a fpring fhorter, and on that account would increafe its 
powe7, it alfo makes it both narrower and thinner, and on this account 
would: diminifh its power, inthe fame proportion; accordingly, by ex- 
_periment, he found that a fpring of twelve inches long, made faft at one 
end, and having a weight fufpended from the other, did not fuffer the 
weight vifibly to defcend, upon being heated even to fucha degree as to 
evaporate a drop of water applied toit. If the above pofition be truc, the 
thermometer-curb, applied to Harrifon’s and other time-pieces, inftead of 
being an advantage, muft be directly the contrary. 
3. A defcription, accompanying a model of a machine, which the 
author calls.an E/evator—Motto, Nititur in ardua V, irtus—Read Decem- 
ber 2, 1791. 
The machine is a compound of perpendicular fhafts, fo conne€ted by 
grooves, ropes and pullies, that each moves its inmate, and thus all 
rife together. 
“This machine,” the author obferves, “ may be applied to many im- 
portant ufes—A perfon of common weight may afcend an hundred feet 
upon a frame of light conftru€tion to gain a rocky precipice, to enjoy a 
fine profpect, to reconnoitre the encampment ofan enemy, and todifcover 
land at fea.x—Difpatch 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 regula- 
ting and governing the fails of a veflel at fea—Signature I. S. S. 
Read November 2, 1792. 
The author propofes, 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 dire@lly a-ftern, be 
‘t right angles with the plane of the fail, a fide wind would ftrike the 
pane of the fail at an angle of forty-five degrees, and a wind four points 
beiore the beam, would {trike the fail at an angle of two points andan half; 
andthus, it is prefumed, that the mere action of the wind upon the 
Aaa vanes 
