ON SNOW CRYSTALS. 109 



mentions that the largest crystal represented was ^ of an 

 inch in diameter, the smallest ^" z Dr. Nettis remarks, — 

 " the natural size of most of the shining quadrangular parti- 

 cles, and of the little stars of snow, as well the simple as the 

 less compound ones, does not exceed the twentieth part of an 

 inch." 2 It is possible that there might have been very minute 

 figures, which, from our manner of observation, may have es- 

 caped our notice ; but those which we did observe, and were 

 able to identify, generally exceeded very considerably the 

 sizes recorded by the above authors. To fig. 39 of Nettis 

 (No. 6 ? of Scoresby) he has attached a mark denoting the 

 natural size. This is less than a line in diameter, and is con- 

 sequently only one- third the size of some similar in form which 

 came under our observation. Some of ours very considerably 

 exceed the extreme size mentioned by Nettis, and equal the 

 largest described by Scoresby ; and their average diameter 

 was such that the unassisted eye could discriminate the va- 

 rious figures as they lay on a dark ground, and could even 

 detect some of the varieties floating through the air, their de- 

 scent being slow in consequence of the calmness of the day. 

 After falling they remained undissolved, retaining, from the 

 freezing state of the atmosphere, their undiminished sharp- 

 ness and perfection of figure, and continuing obvious to the 

 most unpractised eye which should chance to fall upon the 

 wood or metal on which they were conspicuously exhibited. 

 Judging from their abundance in such situations, they con- 

 stituted fully one-third of what had fallen. 



It is worthy of remark that all the varieties figured by 

 Hooke in his ' Micrographia,' published in 1665, or by Dr. 

 Nettis of Middleburgh, in 1740, and the whole of those ob- 

 served by us, belong exclusively to the "lamellar," or first of 

 the genera into which they are divided by Scoresby. All, 

 with the exception of Nos. 5 and 19, were "perfect figures," 

 and we may also add " many instances occur of mutilated 

 and irregular specimens ; some wanting two or three radii, 

 and others having radii of different sizes and shapes." We 

 observed also that an excess instead of a deficiency of some 

 of the parts occasionally interfered with the geometric accu- 

 racy of the figures ; a circumstance which did not escape the 

 minute accuracy of Dr. Nettis, who gives two representations 

 (Nos. 57 and 84) of " anomalous figures of snow," of which, 

 he adds, " there is an infinite variety." 



In the observations made by Mr. Hooke and in those by 

 Dr. Nettis, on lamellar crystals, no information is conveyed 



1 'Arctic Regions,' vol. i. p. 431. 2 ' Phil. Trans.' part i. 1755, p. 674. 

 Vol. III.— No. 27. n. s. m 



