8. B. Williams — New Type of Mercury Air-Pump. 15 



There are no valves or stop-cocks or cone-shaped bearings to 

 cause a leak just at a critical moment. It is extremely simple, 

 both in construction and operation. Any one who has used a 

 mercury pump knows how exasperating it is to have a connection 

 break at some point and the mercury violently thrown through 

 the pump by the inrush of air, and as a result a pool of mercury 

 and a pile of broken glass in the middle of the floor. If any- 



FlG. 1. 



thing breaks about this pump the mercury simply runs back 

 through the tubes into the chamber C and no harm done. 



It is also apparent that this pump exhausts directly against 

 atmospheric pressure, which the average laboratory will And a 

 decided advantage, as it does not require a second pump in 

 tandem with it. If the cover, L, were air-tight and the buck- 

 ets driven by a shaft passing through B in an air-tight bearing, 

 it would be possible to shorten the tubes T x and T 2 , but this 

 would then necessitate another pump attached in tandem and 

 exhausting from chamber C. The buckets may take on any 

 design or shape. Not only the buckets but also the chamber 



