This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
The ventilator consists of a piece of wood, about 8 in. wide, 3 in. thick and as long as the window is wide. Holes, 1 3/4in. in diameter, are bored at regular intervals into one edge and these are connected with openings from one side as shown. The piece is set under the lower sash with the long openings toward the outside. This will direct the incoming air currents upward into the room.
Ill: The Ventilator Prevents the Air from Entering a Room in a Straight Line