Cut a 2’x3′ triangle out of a piece of thin plastic. Tape a dime to the tip of the triangle. On the 2′ side of the triangle push a nail through the plastic and make sure that it will free spin, this will make the pointer. Glue 3 strands of human hair that is at least 8′ long some where between the nail and the dime. Hammer the nail that is in the pointer 6′ from the top of a sturdy piece of wood measuring 9’x4′. Directly above that nail hammer in another nail about 1′ from the top. Glue the free ends of the hair to the nail that is 1′ from the top and you have yourself a hygrometer.