586 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



Dr. Rowell explained by the aid of a diagram the manner in which air 

 was used to clean grain in Hecker's Metropolitan Mills, where it was found 

 much easier to draw the air than to force it through tubes. The tcmperar 

 ture was reduced 5° within the tubes. 



Mr. J. A. Miller read the following paper : 



On THE Use of Heated Air Slightly Compressed. 



Compressed air as a motive power is certainly useful in localities where 

 steam or water power cannot be employed, as in mines and tunnels; but 

 this question of compressed air as a motive power has a far wider JBeld 

 than has yet been examined. Taking calo pofentia est as an ascertained 

 truth we must admit that the loss of heat is the loss of power. Now with- 

 out going through the minutite of a calculation I will simply state, that by 

 careful experiments and calculations, it has been ascertained that in a pud- 

 dling furnace with a stack thirty-five feet in height, 500 pounds of coal are 

 required to move a certain quantity of air by rarefaction, at sufficient 

 velocity to ensure combustion; whereas one pound of coal expended in a 

 Cornish boiler wiL by the power of steam, employed through the medium 

 of a fan blower, supply the same quantity of air to the fuel during the 

 same time. The same proportions exist in our steam boiler furnaces, and 

 as fuel forms the standard of cost for all steam power, it must be apparent 

 that a large saving is effected by the use of compressed air in a proper 

 manner; as a motive power it will be at once the simplest and most effec- 

 tive application. It must be also apparent that whatever heat once gene- 

 rated which might be used for other purposes is most prodigally wasted 

 when allowed to escape through a chimney. If compressed air were forced 

 through pipes in our streets there would be no further use for the tall and 

 costly chimney stacks which now disfigure our factories. But besides this 

 a saving of at least fifty per cent of fuel would be effected; this is an 

 immense item. If by some means every chimney in our land could be 

 destroyed and compressed air be properl}'' introduced into our furnaces, and 

 all chambers of combustion, the saving effected would pay the full interest 

 on our National debt and provide an ample sinking fund for its early 

 redemption. So much as to compressed air as a motive power. 



But, Mr. Chairman, this question of compressed air is of such magnitude 

 and importance that all other questions become secondary when compai-ed 

 with it. Light, heat and water are necessities without which no human or 

 even brute being can exist for but a short time, and yet for a time they 

 . may be dispensed with; but air is the very breath of life without which no 

 being can exist. Now the pure atmosphere consists of one volume of oxy- 

 gen and four of nitrogen, and as oxygen is the life giving principle, the 

 very supporter of life, it is evident that the purer the air and the more 

 compressed its volume the more oxygen is inhaled by each operation of 

 breathing, and as a consequence the deeper, less frequent and less painful 

 the inhaling to those suffering from lung diseases, whose number is legion 

 as well as more invigorating to those in the enjoyment of health. 



The celebrated French author, M. Junot, says, on this subject: — 



"When a person is placed in condensed air, he breathes with increased 

 facility, and feels as if the capacity of his lungs was enlarged; his respir- 



