'214 PHILOSOPHICAL TRANSACTIONS. [aNNO 1746. 



the following trial : He took his tin tube, which has 2 arms to it, directly oppo- 

 site to each other, and at that distance from one end of the tube, which is equal 

 to the length of one of the arms; this he suspended by a silk line from the 

 ceiling of the room, letting it hang down of a convenient length. He then took 

 a China basin, holding better than a quart, and having nearly filled the same 

 with water, he stood on the wax-cake, with this basin of water in his hand, so 

 near the pendulous tube, that he could apply the basin to it with convenience; 

 then having suffered himself to be electrified, he held the basin so under the 

 tube, that the lower end dipped about an inch in the water; on this a person 

 approached one end of one of the arms with the spirit of wine in a spoon, and it 

 was immediately kindled with vehemence; and at the same time he received on 

 one of his fingers that held the basin a pungent stroke; and that stroke was 

 given the very instant of time the snap was at the spoon, or any other object 

 that was applied. 



■ • He thinks there can be no doubt, but that water is as good a medium of com- 

 munication to the effluvia, as any substance whatever; for he is certain that all 

 those which came to the spirit, were conveyed to the tube by the water ; since 

 the tube dipped in the centre, and was then motionless ; so that it never came so 

 near the basin as to receive any effluvia from it. 



Description of an Improved Hygroscope. By Mr. Wm. Anderon, F. R. S. 



N° 479, P- 95. 



On comparing many different hygrometers together, none appeared to come 

 nearer the truth than that recommended by Mr. Boyle, of weighing a piece of 

 sponge in a pair of gold scales. But the difficulty and time Mr. A. found re- 

 quisite to adjust the weights, and discover the true state of the air, set him on 

 contriving another method, by which at all seasons he might perceive, by in- 

 spection only, the most minute alterations with respect to moisture or dryness ; 

 and is as follows. 



In fig. 3, pi. 4, A represents a thin piece of sponge, so cut as to contain as 

 large a superficies as possible. This hangs by a fine silken thread on the beam b, 

 and is exactly balanced by another threat at d, strung with the smallest lead-shot, 

 at equal distances, and so adjusted as to cause the index e to point at g, in the 

 middle of the graduated arch fgh, when the air is in a middle state between the 

 greatest moisture and the greatest dryness, i shows a little table or shelf, for 

 that part of the silk and shot which is not suspended, to rest on.. Hence the 

 effect is evident. 



