oct. — mar. 1859-00.] Rooms in Tropical Climates. 317 



calculating from the Kinneil experiment,' a one horse power (which 

 in India w T ould generally be represented by a pair of bullocks,) and 

 might cost, with their driver, two shillings per diem (would be en- 

 abled to furnish a room with 50 or 70 cubic feet of air per minute, 

 20° Fahr. below the surrounding atmosphere. This being a quan- 

 tity of air abundantly sufficient for the breathing of one or two 

 persons at least, and 20° being quite sufficient depression of tem- 

 perature for the inside of the room below the atmosphere outside, 

 we see that, in so far as the element of mechanical force is con- 

 cerned, the expense is nothing extraordinary ; certainly trifling to 

 an Indian purse. In some places the regular blowing trade-winds, 

 and, in others, water power, may give the means of producing me- 

 chanical force . still cheaper. Sometimes the abundance of fuel 

 may render a steam engine convenient, but seldom need the neces- 

 sary power cost more than the bullock hire ; and this element of 

 expense, which is to be compared, in the warming economy of colder 

 countries, with the price of coal, is reduced within very possible 

 limits indeed. 



But we have next to consider the form and size of the apparatus 

 to which the mechanical power shall be supplied, not only in order 

 that this may be used to the best effect, but to contract as much as 

 possible the first cost of the whole ; a capital to be compared to 

 that sunk in cold countries, in furnishing a house with grates and 

 chimneys. Then a method has to be devised of supplying the air, 

 thus produced, to a room in such a manner as to produce perfect 

 ventilation ; and, lastly, a plan of drying the cooled air, should 

 that be found necessary, as it is not at all improbable. 



Before the form of the apparatus can be arranged, a necessary 

 preliminary is to decide on the most proper degree of compression 

 to be worked to ; especially to ascertain whether the force of the 

 compressed air may not be usefully employed in assisting to com- 

 press more air ; the apparent advantage being then, that the me- 

 chanical power consumed would be little more than just sufficient 

 to overcome the friction of the machine, and make up for leakage; 

 the power employed for the compression of the air being all got 

 back again on its expansion, and this great economy of force greatly 

 over -balancing the attendant disadvantage of increased complexity 

 in the apparatus. 



