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.
This latch is suitable for outbuildings, small shops and sheds, as it can be opened from both sides of the door and is easily applied. It consists of a rod of suitable size which is bent in the shape shown in the sketch after the rod is inserted through a hole bored near the edge of the door. The spring of the metal will hold the catch in place.