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 double clothesline of any length should have a supporter in the center to keep the line from sagging when the clothes are hung on the lower one. The supporter shown in the sketch saves the wear from the strain on the lines. It also keeps the clothes in a higher current of air so that they dry quicker.
The supporter is made of two nickel-plated rings measuring 2 in. in diameter. They are bound together as shown. The rings being nickelplated, the supporter will not rust the clothes. The clothes should be arranged on the lower line so that the supporter will rest in the center. - Contributed by Katharine D. Morse, Syracuse, New York.