312 A method of cooling the Air .of [No. 10, new series. 



of weighty though the same by measure of oxygen, the supporter of 

 life : but if, in addition to the air being rarified, it be also still 

 further distended by the vapour of water being mixed with it, it 

 is evident that a certain number of cubic inches by measure, or the 

 lungs full, will contain a less weight of oxygen than ever ; so 

 little, indeed, that life can barely be supported, and we need not 

 wonder at persons lying down almost powerless in the hot and 

 damp atmosphere, and gasping for breath. Hence we see 

 that any method of cooling the air for Indians, instead of adding, 

 should rather take moisture out of the air, so as to make oxygen 

 predominate as much as possible in the combined draught of oxy- 

 gen, azote, and a certain quantity of the vapour of water, which will 

 always be present ; and hardly any plan could be more pernicious 

 than the favourite, though dreaded one by those who have watched 

 its results, — of the wet mats. Cold air, i. e. air in which the ther- 

 mometer actually stands at a low reading, by reason of its density, 

 gives us oxygen, the food of the lungs, in a compressed and con- 

 centrated form, and men can accordingly do much work upon it. 

 But air which is merely cold to the feelings, air in which the ther- 

 mometer stands high, but merely gives us one of the external sen- 

 sations of coldness, — on being made by a punkah or any other blow- 

 ing machine, to move rapidly over our skin ; or on being charged 

 with watery vapour, or on being contrasted with previous excessive 

 heat ; such air must nevertheless be rarified to the full extent indi- 

 cated by the mercurial thermometer, and gives us therefore our 

 supply of vital oxygen in a very diluted form, and of a meagre, un- 

 supporting, and unsatisfying consistence. The only other Indian 

 plan to be mentioned, is shutting up the house in the middle of the 

 day, and opening it only at night or towards morning ; but this 

 evidently will not suit the strictly tropical heat, and can only be 

 employed in the northern and inland portions of India, where the 

 climate is more nearly like that of the " radiation" countries, where 

 the nights are cool ; for otherwise, the closing of a room will evi- 

 dently be no safeguard against the heat which has already saturated 

 the walls, the roof, and the floor ; and if a human being be enclosed 

 in that space, he will evidently warm up the confined air, in addi- 

 tion to contaminating it by his respiration. The sine qua non, 



