Herpeivlogy. aaz 
_ imaterial substanee, the atmospheric particles of a comet may 
have their gravity diminished to such a degree, either by their 
distance from its centre, or by the rarity of the nucleus, as 
to yield to the impulse of the solar rays, and be forced behi 
the nucleus, in the same manner as smoke yields to the im- 
. pulse of the gentlest breeze. 
_ “Tf this theory is well-founded, may we not form an opin- 
ion of the density of comets, by comparing their magnitude 
with the length of their tails; and may we not suppose that 
those comets which have no tails are more dense than others, 
and exercise over the particles of their atmosphere an attract- 
ive force, which enables them to resist the impulse of the 
solar rays.” 
5. Lyceum of Natural History of New York.—The first vo- 
lume of the Transactions of this Society is completed, and 
forms a valuable addition to our collection of documents re- 
Jating to American Science. 
G. Cutting of Steel, &c. by fron 
{Extract of a letter to the Editor from Mr. Isaac Doolittle, dated Ben- 
nington Iron Works, Jan. 24, 1826.} 
Having oceasion, a short time since, to cut a plate of cast 
iron, three-eighths of an inch thick, it was thought that the 
plan recommended for cutting steel by iron might succeed in 
this case. Accordingly a disc of sheet iron was placed on an 
axis, and adapted to a water-lathe, in a manner to revolve 
with great rapidity. This disc would cut hardened or soft 
steel, or wrought iron, with much facility, but produced not 
the slightest effect on the cast iron, though the latter was 
very gray and soft. I confess I am quite at a loss to explain 
this difference in the action of the disc. 
7. Herpetology.—Mr. Samuel F’, Barker, of Andover, states 
that, being employed with others in making a stone bridge in 
the north parish of Andover, they discovered on taking up @ 
large flat stone, (about three feet by five) a great body of 
living snakes, which had probably taken shelter there for the. 
winter. They were stiff at first from the cold, but exhibited 
various signs of life when exposed to the stn. On being 
