2177. Air in hothouses has been recommended to be changed, by Dr. Anderson and others, by means of fans; so as to produce aeration (ï¿½ 2154.). As this is very desirable, the Eolian machine, invented by B. Deacon, may be employed, either placed in the house, and kept in motion by human or mechanical power, or placed at one end to force in or draw out the air. In a range of houses forming a circle or square, or any endless figure, a perpetual breeze might be readily produced in the following manner:ï¿½Place under the floor a powerful fan of the width of the house. Exactly over the fan, place a glass division across the house, and let the fan draw in the air through apertures in the floor on one side of the division, and give it out through similar apertures, or through tubes of any sort, on the other. It is evident, a regular current would thus be produced more or less powerful according to the size of the fan, and the rapidity of its motion.