Shortly after the completion of Washington’s Grand Coulee Dam in 1942, engineers faced a difficult challenge: how to feed a cable through a 24-inch drain, two-thirds filled with grout, that wound 500 feet through the galleries inside the huge concrete structure.

The workers were stumped at first, but they hit on a novel solution. “An alley cat, raised on scraps from the construction men’s lunch pails, was summoned and one end of the 500-foot string was tied onto his tail,” reported the Spokane Daily Chronicle. “He was placed inside the drain, and an air hose was turned on to ‘encourage’ him to go forward.

“The feline scampered through the drain and was caught emerging at the other end, where he was freed. From then on it was a simple matter to tie a rope onto the string and then the cable and draw it through the drain.”

Physicist R.W. Wood had hit on the same technique 30 years earlier.