184 GLAISHER, ON SNOW CRYSTALS. 



with a still ascending temperature, the snow was replete with 

 simple, stellated forms, chiefly of laminae. Double crystals 

 were very numerous, and I secured sketches of several which 

 I have not yet had time to complete. Fig. 18 represents a 

 double crystal of the prevailing character. I am also again 

 indebted to Mrs. King for another very beautiful and charac- 

 teristic figure, which she observed on this morning ; the 

 minute sets of markings around the edge, have reference to a 

 frosted effect, which communicated additional beauty to the 

 original. 



Owing to the high temperature, the figure of the crystals 

 continued rapidly to change ; collapsing in the most curious 

 and kaleidoscope manner possible, the upper groups of prisms 

 collapsing first, the next in order next, and so on. VVhen I 

 say collapsing, I mean the sudden dissolving of three or more 

 prisms into one, a change effected with instantaneous rapidity. 

 The next stage of dissolution was the rounding of every angle 

 that remained, and the next stage to that, the thickening and 

 elongation of spiculse, which had served as axes to the prisms, 

 and which derived accession from the dissolving and half-fluid 

 matter of the prisms. 



In this manner they continued to exchange one simple form 

 for another still more simple, until the pristine drop of water 

 occupied tl;e site of the former crystal. 



Whilst sketching fig. 18, I saw it undergo a variety of 

 changes, until the several groups of prisms, of which it was 

 composed, collapsed into the figure before you, when every 

 trace of inner markings had disappeared, and the crystal re- 

 mained of a watery transparency, until it finally dissolved. 

 Figs. 19 and 20 are specimens in a partially dissolving state. 

 From fig. 20, the upper prisms have all but disappeared ; and 

 in fig. 19 midway up the pinna? it will be perceived that some 

 of tlie prisms have already dissolved, and given place to an 

 irregular and serrated spike, which somewhat impairs the 

 original harmony of the figure. 



At noon the snow had all but ceased. The temperature 

 attained to 37°. Cocks crew as anticipating a change ; the 

 birds, which for six weeks previously had been silent, 

 answered each other from the trees ; icicles two feet in lengtli, 

 which I had noted for sixteen days previously, were fast 

 melting away : all nature but the birds seemed motionless, 

 as waiting tlie advent of a change ; and, what is rarely seen, 

 the trees were dripping moisture while the snow lay like a 

 rime upon J,heir branches and bended stems. Half an hour 

 after, the thermometer rose to 38^, and a complete thaw set in. 



At 2 o'clock, the thermometer was 35 5° small and fine 



