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.
A moistener for postage stamps or envelopes can be easily made from a screw-top jar. A strip of felt cut as wide as the jar is deep and made into a roll large enough to fit the neck of the jar serves as a wick. The metal top is perforated, and, after tilling the jar with water, it is screwed into place. This makes a very inexpensive moistener for the library desk.