400 Scientific Intelligence. 
among these wagon tracks 1 can see one or two produced by 
some other agency; and it is not improbable that during its 
rough transportation, bowlders might have been forced over it 
in that direction. 
I have regarded the detritus collected along the central part 
of Amherst, where this bowlder lay, as Modhfied Drift: that is, 
coarse drift that has been subsequently acted upon, and more or 
less rounded and sorted by water. Generally the fragments at 
this place are more rounded and of less size than we see in the 
coarse drift upon the neighboring hills, and yet the bowlders are 
considerably larger, though the one now described is much the 
largest I have seen in our modified drift. 
_ As this bowlder seems to me to be of unusual interest, and 
is now placed permanently, through the energy and scientific 
zeal of the class of 1857, where geologists can examine it, I have 
thought this description might be acceptable to the readers of the 
Journal. At any rate, it has been the means of qualifying one 
College Class, as they wander over the world, to examine str 
ated bowlders and ledges. 
—_— _.___ E 
iene een 
SCIENTIFIC INTELLIGENCE. 
I. CHEMISTRY AND PHYSICS. 
On the wave lengths of the most refran ible rays of light in the In- 
terference Spectrum.—E1sENnLopr has Aa ear a ct i 
plane of which is at right angles to the incident ray. Di ‘a 
lattices of different kinds may be fastened immediately in front of the 
object-glass; a white or transparent screen is pl a pro 
( very narrow and n us. 
pnenomena of diffraction described by Schwerd in his classical work may 
in this way be represented so that they may be seen by a number of 
the 
m 
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