170 Prof. Oliver Lodge on the Seat of the 
ment en évidence, grace a la précision des mesures, sont 
au-dessous des erreurs expérimentales de leurs méthodes, ou a 
peine supérieures dans les cas les plus favorables.”’ 
Fig. 9.—Pellat’s Apparatus for experimenting in different Gases and at 
different Pressures. 
The movable plate is now the lower one, and it is pulled down by an 
electromagnet, H, a little way against the springs, B, which tend to 
drive it up against the screw-tops,C. Contact is automatically broken 
at g the instant before separation. The bell-jar has 35 litres capacity, 
the diameter of each plate being 15 centimetres. It must be impossible 
to employ anything like pure gases in a bell-jar enclosing such a bulky 
mass of heterogeneous material; and the pressure was found not to go 
below 2 or 3 centimetres of mercury. However, he has since made a 
smaller arrangement of 1 litre capacity, with plates 9 centimetres 
diameter, and, what is more important, with the electromagnet out- 
side, and nothing inside but glass, mica,and metal. In this the pressure 
goes down to a millimetre. But even this is not all that could be 
wished. Moreover the experiments described had been made with the 
larger apparatus. 
