Door Made of Wind.

Progress, Volume XVI, Issue 1, 1 September 1920, Page 11

Door Made of Wind.

"Doorless doors" that make flyscreens unnecessary and keep out rain and snow without other agency than that of a properly directed air current are described by H. S. Knowlton in "Electrical Mercandising" (published in New York, U.S.A.). They are the invention, he says, of a Boston mechanical engineer, Henry H. Cummings, who is also the inventor of the ship log which was generally installed on vessels of the United States Navy during the war. We read:

_ "As shown in the accompanying diagram, the 'doorless door' consists of a motor-driven fan installed below or behind a grill in the entrance of a store or other building and arranged to draw air downward from the upper portion of the doorway, whence it is carried by a duct to a hood at the top of the entrance and then discharged downward,

completing the cycle. A quarter-horse-power motor driving a sixteen-inch fan and connected with a nine-to-twelve-inch diameter duct provides a current of air under about three-inch waterpressure, which is unnoticed by persons standing in the doorway, but which is most effective in keeping out insects, rain, snow, and cold air. The use of the equipment enables close regulation to be made, with ease, of the interior temperature of the room, and the absence of a closed door, winter and summer, in a trial installation actually increased trade by one-third. The cost of operation is about two cents per hour."