RECENT VOLCANIC ERUPTIONS IN THE WEST INDIES. 
277 
avalanche from the Alt sis on Gemini pass in 1895; all lay pros¬ 
trate in directions radiating away from the place where the avalanche 
came down. 
*- t ^ ^ ^ f o 1 tj as to the sufficiency of the above 
explanation was the fact that these discharges descended slopes of 10° 
and 12 , which are less than the angle of repose for such material—for 
instance, not so steep as the side of an ordinary railway embankment ; 
but we thought that the entangled gases and steam might be sufficient 
to account for the extra mobility of the mass. When we brought this 
explanation before the Royal Society, it was accepted as satisfactory by the 
physicists present. Prof. Sylvanus Thompson, f.r.s., mentioned as con¬ 
firmatory his having noticed that small particles of silica, when heated to 
ledness, mow about the crucible like a liquid; and Dr. Edward Divers, 
f.r.s., in a letter to Nature,'' not only confirms this statement, but points 
out that the liquid-like behaviour of powders at a red heat is most 
marked in cases where gases or vapours are being given off in minute 
quantities by the incandescent particles, which are thus kept surrounded 
each by a thin envelope of mobile gas, and this exactly meets the case 
of the volcanic particles in question. 
* Nature , December 11, 1902, p. 120. 
2 9 APR. m 
