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.
The accompanying sketch shows a handy device for turning up and unscrewing the covers on glass fruit jars. The loop is slipped over the cover and the handle turned in the direction of the arrow. To unscrew the cover, the tool is turned over and the handle turned in the opposite direction.
The loop should be just large enough to slip over the cover easily.
Ill: The Loop in the Leather Grips the Cap Tightly When the Handle is Turned as the Arrow Indicates
It is made of leather and fastened to the wood handle with screws. - Contributed by J. B. Downer, Seattle, Wash.