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 small disk of rubber or leather, placed on a safety pin as shown in Fig. 1, will prevent the fabric which is fastened by the pin from becoming tangled in the spring loop. The manner of using the pin is shown in Fig. 2.
Ill: Fig.1 Fig.2 The Small Disk on the Pin Prevents the Goods from Becoming Tangled in the Coil