Transactions of the Royal Society of Canada 
SECTION III 

SERIES III SEPTEMBER 1916 Vos 

The Structure of Hailstones of Exceptional ee Size 
By Francis E. Lioyp, F.R.S.C. 
Presented by Proressor C. H. McLeop, F.R.S.C. 
(Read May Meeting, 1916) 
At 8.45 p.m. on January 9, 1916, at Carmel, California, there 
occurred a violent hail-storm of short duration. The precipitation 
consisted of hail ranging in size from the usual small opaque, or partly 
opaque, pellets to lenticular masses between two and three cm. in 
diameter, with radiating arms adding variously to the total dimensions. 
At the close of the squall the ground was covered by hailstones of 
most bizarre shapes, and the writer at once made a record, so far as 
circumstances allowed, of some of the most characteristic and signifi- 
cant. As the temperature was not very low the hail melted rather 
rapidly. It was possible, however, to make the following observa- 
tions. The sketches were made hurriedly under some difficulties, and 
are herewith reproduced with no alteration or embellishment. The 
internal structure could be clearly seen, that of the hailstone shown in 
figure 6 being especially clear and convincing. 
1. The chief mass of the hailstone was lenticular, roughly plano- 
convex (figures 6 and 8). This form was easily seen to be general for 
all the larger hailstones. 
2. The chief mass had been built up about a roughly spherical 
nucleus which was usually opaque (figures 3, 4, 6, 9) due to included air, 
or less frequently clear (figure 11). This fact accords with previous 
observations. 
3. Surrounding the nucleus there was a region in which zonation 
was evident. The zonation was prolate-spheroidal in the sense of 
the chief mass (figure 9). Small vesicles were abundant. Large ones 
were not infrequent and when present were always crescentic and dis- | 
posed in such a manner as to show clearly that their shape was de- 
termined by the same conditions as determined also the shape of the 
Sec. III, Sig. 1 
