Dr. Deane’s Letter t0 Dr. Mantell.. «188 
of the foot of an animal, with all its appendages, we may thereby 
reconstruct its corporeal frame? Comparative anatomical science 
owes its absolute certainty to the uniform operation of nature’s 
laws; they are constant, and this consistency is the key that de- 
ciphers the mysterious dialect engraven upon the enduring rocks. 
We learn from this imperishable record that the footmarks of 
Connecticut River are none other than real vestiges of birds stri- 
ding over the earth, in a period of its existence so remote, that 
the imagination is overwhelmed with the conjecture of its dura- 
tion. It is impossible.to stand upon the ancient rock and see the 
faithful characters engraven there, without yielding to the irre- 
sistible truths they reveal. | It is there that, rejecting hypothesis, 
we bow to the supremacy of truth, because we feel its all-con- 
straining power.) i es hae ; + ae 
Not the least interesting of the fossil remains of this ancient 
rock are the impressions produced by the fall of rain-drops, some 
fine examples of which I add. They exist under the actual con- 
ditions regulating footsteps, and not unfrequently both are found 
upon the same surface. The track No. 1, is an instance, although 
not very striking. My attention was foreibly arrested when gath- 
ering these minerals, by observing an analogous appearance upon 
the mud of the river's bank, within a few feet of the rock whence 
the specimens were taken. ‘They were similar, with the excep- 
tion that the recent impressions only required the action that 
operated upon the ancient to convert them into beautiful fossils. 
Tracks of living birds are extremely numerous upon the alluvial 
mud of Connecticut River, and when’ indurated by the action of 
the summer’s sun, their entire removal is frequently easy. 
-L have thus thought proper, dear Sir, to accompany these me- 
morials of extinct existence, with such remarks as may perhaps 
serve to explain the manner in which they exist. But after all, I 
leave them chiefly to tell their own story, for they reveal in silent 
though eloquent language, the events that occurred in a period of 
time so far back in the infancy of our earth. I deem that they 
could scarcely fall into better hands, for Iam not unacquainted 
with the surprising discoveries in fossil geology, developed by 
your agency. I have never studied them without gratification, 
for the bright light thus thrown upon the mysteries of creation. 
» Jam, dear sir, most respectfully, your obedient servant, 
ets: } James Deane. 
Greenfield, Mass., Sept. 20, 1842. 
