For the experiment, 200 feet of one-inch iron pipe, which was screwed together in a single long piece, was laid across the north floor of Halemaumau. Ten assistants were distributed along the pipe twenty feet apart, and I stood on the rampart with Alec at the edge of the central portion of the lava lake. This was a high bank ten feet or more above the streaming liquid lava. The men were instructed to lift the entire long tube and walk forward with it, so that it would plunge into the liquid lengthwise, arching down toward the center of the lake as it came past me. Alec helped guide the pipe over the bank, and the men came forward with it at a steady walk. The end of the pipe, covered with a screw cap, was plunged into the liquid lava, traveling toward the bottom at a good speed. The strong current toward the left dragged it somewhat, but not enough to prevent its sinking. After two and a half 20-foot joints of the pipe had plunged into the liquid at a slope of about fifty degrees, I could feel the pipe encountering the increasing resistance of a pasty bottom. Continued forward progress of the pipe caused it to stop and arch up, while the surface lava streamed past it, and its lower end was definitely stuck in the bottom substance of the lake. I then gave the signal to the carriers to try to walk back to the place where they had started, with a view to pulling the pipe up and recovering the terminal length. The pipe trailed upward out of the lava lake like a red hot rope, then stuck and refused to come out. It came close against the bank where it was frozen solid in the stiff blankets of pahoehoe crust, which gripped it like hot iron. The terminal length had been equipped internally with a spiral of spring steel, containing Seger cones which are used in the porcelain industry and which bear numbers indicating they melt at graded temperatures. This first thermometer by meltability was never recovered. The free lengths of pipe had to be unscrewed close to the bank, and four twenty-foot lengths were lost. In later tests we learned to keep the pipe oscillating back and forth so it would not freeze. The epoch-making significance of this experiment was not understood until later. Calculation of the angle of slope of the pipe, where it went down into the liquid and hit on the bottom, showed that vertically the liquid was about fifty feet deep. With the aid of soldiers from the Kilauea Military Camp, this experiment was repeated several times; and each time the lake was found to be the same depth.