This section is from the book "Cassell's Cyclopaedia Of Mechanics", by Paul N. Hasluck. Also available from Amazon: Cassell's Cyclopaedia Of Mechanics.
A simple method of cooling air which is drawn by a fan from the outer atmosphere is to make a frame and cover it with coarse canvas or cloth having lar_e interstices, and across the top of the frame carry a pipe with small holes bored in it so that water can be made to trickle slowly over the whole of the canvas. The water could be cooled with a little ice if necessary. There must be a trough or channel to receive the water at the bottom of the canvas, and the frame must be erected to fit an opening so that the whole of the incoming air will pass through the canvas. Have the frame of good size so that the air will not be forced through it too swiftly.
 
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