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.
When printing postal cards and working fast, it always bothered me to hold the negative in the printing frame while removing the card. To overcome this trouble I decided to contrive some arrangement to hold the negative in the frame when the back was removed. The device I made consists of a thin, flat spring, about 1/8 in. wide and as long as the width of the frame opening. Two lugs are formed and soldered to the ends, as shown in Fig. 1, for holding the plate, and a central lug is soldered on to provide a means of fastening the spring in position. A groove, about 1/16 in. deep, was cut in the opposite end of the frame to receive one end of the negative.
In use, slide the plate into the frame and into the lugs on the spring, and push the spring upward until the plate can be slipped into the slot at the opposite end of the frame. The pressure of the spring, as shown in Fig. 2, will hold the plate securely. The frame can be handled quite roughly and as fast as desired without any danger of the plate falling out. - Contributed by Thos. L. Parker, Wibaux, Montana.
Ill: The Spring with Its Clips and Manner of Holding a Negative in a Printing Frame
A number of bright tin disks tied to the limbs of a fruit tree will prove an efficient means of driving away infesting birds.