202 



LORD KELVIN, DR. M. MACLEAN, AND MR. A. GALT, ON THE 



top to bottom. To the foil at the shoulder is attached a metallic disc, D, of 5 centims. 

 diameter, and having a small hole to allow a connecting wire from the quadrant 

 electrometer to be quickly hooked or removed. 500 cub. centims. of Loch Katrine 

 water having been put into the bottle, its mouth is stopped by hand, and the bottle 

 vigorously shaken for 5 seconds, thoroughly and violently mixing the enclosed 

 2000 cub. centims. of air and 500 of water. It is now immediately placed on a block 

 of paraffin, P, and the disc, D, is connected to the electrometer. A bent metallic tube, 

 T, supported by an insulating paraffin stopper, is placed in the bottle, and a foot 



Curves 1, '2, 3. 



0-7 

 0-6 



0-3 

 0-2 

 0-1 



o i 

 0-2 



\ 



fercenf. 



ren 



\/ 



V 0-4 



j: 



06 

 07 



length of rubber tube connects it to one end of a paraffin tunnel, from the other end 

 of which a rubber tube, 2 metres long, passes to an aspirator consisting of a large bell 

 jar, 13, of capacity 8500 cub. centims., filled with water, and resting on supports near 

 the water surface. The metallic guard-screen, S, which surrounds the bottle, is always 

 connected to the sheath of the electrometer. The outer surface of the bottle is always 

 wet. Less than half a minute is required after shaking the bottle to make the neces- 

 sary arrangements and connections. The electrometer terminal connected with the 

 bottle is now insulated, and then, by opening the stop-cock of the aspirator, " air is 

 drawn rapidly out of the insulated bottle, its place being taken by air flowing in 



