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A. E. Foote—Jagn Vacuum or Filter Pump. 361 
Journal, March, 1878, has in my hands proved difficult of con- 
struction, works badly unless perfect, and quickly wears out. 
a4 device is exceedingly simple and easily constructed. It 
can be made of common materials by any plumber, or gas fitter. 
It has been in use in this laboratory for some months, and we 
easily produce by it a vacuum of twenty-five inches of mer- 
if The following is a description of the apparatus as modi- 
fied by myself. 
A is a tube about four feet long, and from three-eighths to 
ne inch in diameter. To the side of this an arm B is affixed, 
poutchoue vibrating tube which conducts the supply of water 
: The upper part of A over which C is thrust, 1s cut off 
abe {Bele of 40°. ‘The vibrations are regulated by a movie 
_ am D. To B is attached a rubber tube E, which leads to 
ti € vacuum bell jar or bottle. Within B and near its connec- 
*nwith A, is fixed by cement, the valve represented in fig. 2. 
