322 PHILOSOPHICAL TRANSACTIONS. [aNNO 1717. 



Upon my giving an account of the success of this experiment to the Royal 

 Society, they ordered me to repeat it before them on the 5th day of Dec. 17 17, 

 being the Thursday next after the yearly meeting for choosing officers on St. 

 Andrew's day ; on which day an annual experiment is appointed to be made, in 

 conformity to the will of their late worthy member and benefactor Sir Godfrey 

 Copley. I made the experiment first with two of the receivers ; then with all 

 the four; dropping a guinea and a small piece of paper together; and the suc- 

 cess answered expectation. But not being willing to try with a down-feather, 

 because I feared the air might insinuate between some of the glasses, by reason 

 the number of persons present shook the room, the society ordered me to 

 make the experiment at home before one or more of their members. Accord- 

 ingly Martin Folkes, Esq. a very ingenious member of the society, did me 

 the favour to be present when I made the experiment at my house; where we 

 made four trials in the following manner. 



The whole machine being fixed, as abovementioned, we first let fall a guinea 

 and two papers; the one placed over, and the other under it, before any air 

 was pumped out; and the guinea came to the bottom when the papers were 

 only in the middle of the second glass from the top. Then having laid a 

 feather on the brass-springs close by the guinea, we let them loose both to- 

 ther; and the feather was fallen only down to the 4th part of the length of the 

 first glass or -^ of the whole distance, when the guinea was got down to the 

 bottom of the receiver. We then laid two papers and two feathers, one of 

 each under, and the other over the guinea between the springs; and having 

 drawn out so much of the air as to bring up the mercury in the gauge-tube 

 within a quarter of an inch of the greatest height to which it could be then 

 raised by the pressure of the external air, we caused the bodies to fall all at 

 once: and though the papers came down to the bottom at the same time 

 as the guinea, yet the feathers, being much lighter, wanted about three inches. 

 But at last, having laid the papers, feathers, and guinea, as before, we pumped 

 out all the air, and then the feathers, as well as the papers, came to the bottom 

 of the receiver at the same instant of time as the guinea. 



An Account of a small Telescopical Comet, seen at London the lOtk of June, 

 1717. By Edm. Halley, LL. D. R. Soc. Sec. N** 354, p. 721. 



That the number of comets traversing our solar system is much greater than 

 some, on account of the late rareness of their appearance, have supposed it, 

 may be collected from several small ones which have within few years been de- 

 scribed in the memoirs of the French Royal Academy of Sciences ; those dili- 

 gent observers assuring us that they discovered one in Sept. 1698, another 



