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 simple and easily constructed graduate holder in the form of a bracket placed in the corner of a dark room is shown in the sketch. The bracket not only holds the graduates securely, but allows them to drain perfectly and prevents dust settling on the inside, as they are suspended by the base. Holes of different size are cut in the board to accommodate large, medium and small graduates.