Perry worked as Lord Kelvin's assistant at the University of Glasgow, and later became professor of mechanical engineering at Finsbury Technical College.
[1] He was a colleague of William Edward Ayrton and John Milne at the Imperial College of Engineering in Tokyo, 1875–79, and was also a Fellow of the Royal Society.
Although others (Max Schuler in Germany, Sperry in the USA) had been working on developing practical gyrocompasses, Perry collaborated with Sidney Brown to further develop these and they were awarded U.S. patent 1291695A : "Gyro-compass" by John Perry, Sidney George Brown, filed August 1917; granted 1919.
It was not until the discovery in 1903 that radioactive decay releases heat and the development a few years later of radiometric dating of rocks that it was accepted that the age of Earth was many times greater, as Perry had argued.
Kelvin rejected this idea as there was no evidence of tidal deformation of the Earth's crust, and in response Perry made a reference to Kelvin's favourite demonstration of the slow deformation of shoemaker's wax to illustrate the supposed qualities of the presumed luminiferous aether thought then to be necessary to transmit light through space.