VOL. XXV.] PHILOSOPHICAL TRANSACTIONS. 289 



which I knew would plentifully adhere to and lurk in the irregular body of the 

 weight, had it been fixed to the outside. Thus provided, and the bottle closed 

 with common air, it was suspended by a wire at one end of a very good balance, 

 and being in the water it was counterpoised by a weight of 3854- grains in the 

 scale hanging by the other end. Then being taken out and screwed to the 

 pump, it was in 5 minutes time pretty well exhausted, the mercury in the 

 gauge being elevated to near 29^- inches. It was then taken off the pump, but 

 first, by turning a cock that screwed both to it and the pump, the air was pre- 

 vented from returning into it. In this manner it was again put into the water, 

 and suspended as before to the balance, and it then weighed but 175^ grains, 

 which subtracted from the first weight, gave 183 grains the difference, and was 

 the weight of the quantity of the air drawn from the bottle by the pump. Then 

 opening a cock under water, this was at first violently impelled into the bottle, 

 but abating gradually of its force, till such a quantity had entered as was equal 

 to the bulk of air withdrawn. So that by making the experiment after this 

 manner, we need not be very solicitous in the nice exhaustion of the receiver, 

 for it must of necessity answer reciprocally to the respective quantities taken 

 out, the remaining air being weighed at last as well as at first, and no greater 

 quantity of water can enter the receiver than what will supply the space deserted 

 by so much air. The bottle now being again weighed, it was found to be 

 162132 grains. From which 1754^ grains being subtracted, which is the weight 

 of the bottle more than its like bulk of water, there remained 161956-i- grains, 

 which being divided by 183 grains, the weight of the air taken out of the re- 

 ceiver, gave the proportion as 885 to 1 . The avoirdupois weights being brought 

 to ounces, I reduced to grains, by multiplying them by 438, the exact number 

 of grains contained in an ounce of that weight. The column of mercury in 

 the barometer at the same time measuring 29.7 inches. The season of the year 

 is to be considered, which was May, and I doubt not but if the experiment be 

 repeated in December or January, a sensible difference will ensue. 



u4n Experiment made at Gresham College, showing that the seemingly Sponta" 

 neous Ascent of Water in small Tubes, open at both Ends, is the same in Fiacuo, 

 as in the open Air. By Mr. Fr. Hauksbee, F,R.S. N° 305, p. 2223. 



I took three pieces of small tubes of diflferent bores, and fixed them in a 

 piece of cork directly perpendicular, with their lower orifices as nicely even as I 

 Gould. The same cork I likewise fastened to a wire, which passed through some 

 collars of leather, included in a box on the upper plate of the receiver ; by 

 which means, I could at pleasure elevate or depress the tubes without any dan- 

 ger of the air's insinuation. Thus prepared, and tinged water set on the plate, 



VOL. v. P p 



