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.
It is difficult to catch muskrats in an ordinary steel trap, as a broken bone allows them to sever the flesh and es- cape. During the summer these rats build a shelter for the winter constructed of moss and sticks placed on the river or lake bed, the top extending above the water level and the entrance being through a hole in the bottom near one side, while the passage itself is under water. It, therefore, only remains for the trapper to make one of these houses over into a huge wire trap so that the animal may be caught alive.
Ill: A Trap for Catching Muskrats Alive in One of Their Mounds Built of Moss and Sticks
The house A is prepared by removing the top and building the trap from heavy mesh wire which can be easily shaped, the joints being held together by binding the edges with wire. The passage is then fitted with a double trapdoor, the first, B, provided with sharp points on the swinging end, while the other is a falling cover. These two doors are placed in an entrance way, C, made of wire mesh and fastened over the passageway.
The muskrat comes up through the passage, pushing a bunch of moss or sticks and does not notice passing the trapdoors. The upper door is to keep the animals caught from getting at the first door. - Contributed by Vance Garrison, Bemidji, Minn.