Mr. Ingalls of _Scientific American_ read an article by me in which I described my shock recorder and thought it would lead amateur machinists to devise their own machines and to record the vibrations about them. Numerous amateurs did send in designs for instruments, and Ingalls believed that the seismograph hobby would become as popular as the amateur astronomical telescope hobby. But it failed because the amateurs were waiting for earthquakes, which didn’t happen. They were not content with vibrations from trucks, railroad trains, waterfalls, surf on rocks, artillery practice, or wind storms. My improved shock recorder gained some use later in New Zealand and Montserrat, after big earthquakes in those places stirred the authorities to build simple instruments. However, popular seismoscope simply doesn’t exist. The range finder I had been working on since my teaching days in Massachusetts Tech, where I had made an optical device with a traveling index mirror which moved along an upright scale of centimeters, and a sextant telescope. The idea was a transit, with self-contained base line close to the operator. My theory was that in such measurements of distance as we had to use--to about a thousand feet or less, to the lava fountains in the bottom of Halemaumau pit--we might read off the vertical distance from a single station, when all other stations were enclosed in smoke. In the Aleutian Islands and elsewhere I experimented with a Zeiss stereoscopic rangefinder designed for artillery ranges, but it was not accurate enough for short distances. Everything in my instrument depended on moving a telescope parallel to itself with superlative precision, on a scale within the instrument. I finally hit upon using a track of taut piano wire, probably the straightest line in all mechanics. If one first looked at an object twenty miles away (infinite distance), the telescope could be moved along right and left and the image would remain immovable on a vertical hair. If it were now focussed on an object 1,000 feet away, the displacement of the telescope on the centimeter scale would measure the distance with a high degree of accuracy. This was the stadia principle inverted to contain the rod at the observing position. I also made several graphic devices for surveying Halemaumau daily from the rim benchmarks. However, when lava overtopped the rim and destroyed the datum posts, mapping became difficult.