54 



SCIENCE. 



[N. S. Vol. XVII. No. 419. 



rotary saw for sawing car roofs, pneumatic 

 hammers, chisels and caulking tools, flue 

 welders, boring and valve-facing machines, 

 rail saws, machine for revolving driving- 

 wheels for setting valves, pneinnatic paint- 

 ing and whitewashing machines, dusters 

 for ear seats and the operation of switch- 

 ing engines about the yard. It is also used 

 in the foundry for pressing and ramming 

 molds, and for cleaning castings by the 

 sand blast; but its greatest field of useful- 

 ness is its application to hoisting and lift- 

 ing operations in and about the works. 



New applications of compressed air are 

 constantly being made, and each new use 

 suggests another. This has a tendency to 

 increase the number of appliances which 

 are intended to be labor-saving devices, 

 but in many cases the work could be done 

 just as well and much more cheaply by 

 hand. 



A case in point is seen in an apparatus 

 which was at one time in use on one of 

 our prominent western roads. It was a 

 sort of portable crane hoist which could 

 be fastened to the smoke-stack of a loco- 

 motive, whereby one man could lift off the 

 steam chest casing. The hoisting appa- 

 ratus weighed about twice as much as the 

 steam chest and took three men to put it 

 up. When piece work was adopted two 

 men easily lifted off the steam chest and 

 this 'time and labor saving device' M'as 

 relegated to the scrap heap. 



While compressed air has been used to 

 some extent for inducing draft in forge 

 fires, it is unquestionably a very expensive 

 method. Tests to determine this show that 

 it costs twenty-five times as much to pro- 

 duce blast in that way as it would with a 

 fan.* 



The success and economy which has at- 

 tended the use of compressed air in so 

 many lines of work has led to its adoption 

 in fields which are much better covered 



* Proc. Western Ry. Cluh, 1898. 



by electrically operated machines. While 

 compressed air has been used under certain 

 conditions very satisfactorily to operate 

 pumps and engines, printing-presses, in- 

 dividual motors for lathes, planers, slot- 

 ters, dynamos and other work, it does not 

 follow that it is always an economical 

 agent under these various uses, or that 

 other methods could not be used even more 

 satisfactorily in the majority of cases. 



It has been proposed to use individual 

 air motors in machine shops and do away 

 with all line shafting, except possibly for 

 some of the heavier machinery. This use 

 of compressed air seems entirely outside 

 the pale of its legitimate field; the general 

 experience thus far indicates that rotary 

 motors are not at all economical and gen- 

 erally are not as satisfactory as electric 

 motors. 



Exceptions are to be found in the small 

 portable motors for drilling and similar 

 operations, to which electricity is not at 

 all adapted and where compressed air has 

 been found to give excellent results. The 

 saving obtained by the use of such portable 

 drills as compared with a ratchet drill is 

 very marked. 



Although these tools are very successful 

 they are still rotary motors, not exempt 

 from some of the objectionable features 

 which seem to be inseparable from them. 

 It is not surprising, therefore, to find a 

 tendency to employ reciprocating pistons 

 and cranks in these portable machines and 

 we note such tools weighing only forty 

 pounds capable of drilling up to two and 

 a half inches diameter. 



While the field is to some extent limited, 

 yet the uses of compressed air are cer- 

 tainly not few, and in many lines of work 

 marked economy result's from its use. 



In most cases no attempt has been made 

 to use the air efficiently; its great con- 

 venience and the economy produced by its 

 displacement of hand labor have, until re- 



