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SCIENCE 



[Entered at the Post-Office of New York, N.y., as Second-Class Matter.J 



A WEEKLY NEWSPAPER OF ALL THE ARTS AND SCIENCES. 



Seventh Year. 

 Vol. XIV. No. 360. 



NEW YORK, December 27, i5 



Single Copies, Ten Cents. 

 13.50 Per Year, in Advance. 



THE HALL AIR-COMPRESSOR. 



exceed twenty-five pounds to the square inch, the compressors 

 shown on this page are intended. 



For any purpose in which a positive air-pressure is required, a These compressors are built by the Hall Steam Pump Company 



compressor possesses many advantages over a fan or blower, of this city, and they are much used for elevating liquids, such as 

 Even for moving air for ventilating purposes, where under ordi- strong acids, etc., as well as for ventilating mines and shafts. They 



THE HALL AIR-COMPRESSOR. 



nary circumstances a blower answers very well, there are times and 

 places in which a positive movement of the air, such as that pro- 

 duced by a compressor, is not only desirable, but actually neces- 

 sary. For such purposes, where the required pressure does not 



are also largely used for furnishing the air-blast where oil, atomized 

 or converted into spray, is made use of on a large scale for fuel. 

 Such a system of burning atomized or aerated petroleum was de- 

 cribed and illustrated in Science of April 5, 1889. 



