100 J. D. Dana on Cohesive Attraction. 
not among the engraved specimens) observations corresponding 
to those made by young Mason, on the remarkable group which 
appeared in March, 1837, (to which reference has already been 
made, ) drawings of which are in our sana on a scale more 
magnificent, and not inferior in beauty, nor, as we believe, in ac- 
curacy, to those figured by the illustrious caine whose 
work we have thus hastily and imperfectly reviewed. We take 
our leave of it for the present, with a grateful conviction that it 
constitutes a grand and noble advance in our knowledge of the 
starry heavens. 
Art. XV.—On a law of Cohesive Attraction, as aliens in 
a Crystal of Snow ; by James D. Dan 
Ivisa genres! fact that. the - most common objects. or occur- 
ane about us, best illustrate the great laws of nature. ‘The 
nary forms of crystal. present the student, as we have 
jy a large part of the laws of: cohesive attraction,* and to 
perceive and ming ate them requires only an attentive enquiring 
ind. he subject of crystallization, cannot long be left to 
which we are indebted to a crystal of snow. The cleavage: of 
crystals indicates, as before explained,} that the force of attraction 
is intermittent in action, and therefore produces seriate results, 
precisely as intermitted reproduction causes seriate results in the 
organic kingdom, giving layers to wood, successive ranges of. 
parts to many plants and animals, and, generally, alternate ac- 
and comparative inaction in growth. ~'This intermitted. 
action in the cases referred to, is an essential anes sales ; 
in each case ; for the resulting characters A 
the chagnetaristies of a species. The a 
tal of snow here figured, escaies a kind. of 
intermittent action dependent on extrinsic cir- 
cumstances. It is a figure of a minute:star 
from an ordinary flake of snow, and is often 
to be seen in the course of a winter. The 
number of different forms figured by 
ae are evidence of the variations of action in the attrac 
tion which extrinsic causes produce, for no two different forms 
Shaye resulted from pean the same exertion of that SDs 
‘ si biases if this Journal, page 364. t Ibi e ae 
urgl ati Plate 503. ~! Pag 
