Another experiment was conducted by Emerson, who was equipped by the Observatory with chemical apparatus to make qualitative analyses of numerous Kilauea products, and he also did critical photographic work, including some photography in the infra-red. In one valuable experiment, he melted Kilauea lava in a refractory crucible at a temperature of about 1200° Centigrade until it was as fluid as honey. Allowed to chill and harden naturally, it was shiny glass like pahoehoe lava. If stirred with an iron rod, it made sprouted black needles, crystallized all through, like aa lava. Thus he proved that stirring made Hawaiian lava crystallize and sprout like fudge, or like the solidification of such metals as silver and bismuth. Sudden outbreak and stirring anywhere will convert pahoehoe to aa; but never does aa become converted physically to pahoehoe, unless flame melts it. The standing pinnacles in the midst of an aa flow, which breaks up into boulders, give evidence of the stirring process. When Emerson’s discovery is applied to basaltic lava flows, it appears that the glassy lava of a source, when stirred by gas fountaining or by flowing, will change from its glassy condition to a sprouting and crystallizing condition. All flows are glassy pahoehoe pumice fountains at source vents, and a quarter of a mile away they become aa. Later the source pahoehoe preserves itself within a glassy skin and pours forward under glassy shells and frontal toes. R. M. Wilson’s work supplied proof of a swelling mountain. Wilson was one of the three leading members of the topographic party of the Geological Survey. The other two were C. Birdseye and A. Burkland. Wilson, whom I had known as a student in M. I. T., was a product of Spofford’s Civil Engineering department and was to become the chief computer of the Survey in Washington. As levelman in Birdseye’s organization, he became topographic engineer of the Observatory, and produced by precise leveling and triangulation the brilliant experiment which showed [the swelling and shrinking of the mountain during fifteen years. By close cooperation with the U.S. Coast and Geodetic Survey we placed a tide gauge at Hilo, both for a sea level base and to record tidal waves. Wilson also, in 1921, ran a level line from Hilo to the Volcano House benchmark, where the Geological Survey had run levels in 1911. The county roadway was marked with bronze plates inscribed with leveling heights, and Wilson’s results showed the edge of Kilauea Crater to be three feet higher in 1921 than it had been in 1911.