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



wherever the supply is drawn from, must be allowed to trickle into 

 the tub, and be conducted by a pipe to the bottom, while an exit 

 being made at the top, the water heated by the compression of the 

 air, will flow off in a continued stream. I have not yet made 

 any experiments on the quantity of cooling surface of pipe required, 

 but a few feet more or less will certainly accomplish it, and will 

 not much increase the expense of the first apparatus which may be 

 made. 



The proposed form is shown in fig. I., where on the left hand side 

 is shown the double acting pump, which compresses the air into the 

 pipe in the tub, where it accumulates until of sufficient elasticity 

 to raise the loaded piston valve on the right; a portion then escapes 

 until the remaining air is less elastic than the pressure on the valve; 

 and at every succeeding stroke of the pump, a quantity of air, 

 equivalent to that forced in at one end of the pipe, will escape from 

 the other end, after having parted with its heat of compression to 

 the water, and expending immediately, and cooling will be avail- 

 ableat once for the sanitary application to rooms. 



The form of cooler mentioned above, is but one of many which 

 may be variously applicable in different situations ; a flat cooler 

 may be preferable, and often it may be of advantage to pass the 

 compressed air through another coil of pipe, over which water is 

 allowed to drip, or which is covered with a damp cloth, so that the 

 cold of evaporation may be superadded to any procurable from the 

 temperature of the water. 



The next point is the application of the cooled air to a room, so 

 as to keep it effectually cooled, and at the same time well ventilated ; 

 and this is, fortunately, very easy to be done, and in the most per- 

 fect manner. 



The cold air being heavier than warm air, ^cannot be applied to 

 upper rooms, or even to lower rooms, with doors and windows 

 reaching down to the ground; for it will escape there as water would, 

 flowing away, and diffusing itself every where over the lowest 

 places. But if a wall, several feet high, be built all round the room 

 proposed to be cooled, or, still better, if it be sunk that depth in 

 the ground, the cold air will be confined as if in a tank," and that 

 which has last come from the pump will occupy the lowest place, 

 while the former supplies, in proportion as they have been longer 



