out two hundred
and fifty pages 12mo. I have taken great pains to collect facts, in this
district, during the two years since my first edition was published. But
I am rather deficient in my knowledge of secondary and alluvial
formations; I wish to trouble you with a few inquiries upon
that subject.

"From what knowledge I have been able to obtain in that department, I am
inclined to arrange the secondary class thus:--

"Breccia: compact, or shell limestone; gypsum, secondary sandstone.

"I leave much, also, for peculiar local formations.

"A gentleman presented specimens to the Troy Lyceum, from Illinois, of
gypsum and secondary sandstone, and informed me that the latter overlaid
the former in regular structure. Myron Holly, and others, have given me
similar specimens, which they represent as being similarly situated,
from several localities in the western part of this State. This
secondary sandstone is sometimes more or less calcareous. I believe it
is used for a cement by the Canal Company, which hardens under water.
Will you do me the favor to settle this question?

"On your way to Detroit, you may perhaps, without material
inconvenience, collect facts of importance to me, in relation to
secondary and alluvial formations. Anything transmitted to me by the
middle of April on these subjects will be in season, because I shall not
have printed all the transition part before that time.

"Have you any knowledge of the strata constituting Rocky Mountains? Is
it primitive, or is it graywacke like Catskill Mountains? I have said,
in a note, that, after you and Dr. E. James set foot upon it, we shall
no longer be ignorant of it.

"I intend to kindle a blaze of geological zeal before you return. I have
adapted the style of my index to the capacities of ladies,
plough-joggers, and mechanics."

_March 28th_.--While here, I received a notice of my election as a
member of the Academy of Natural Sciences at Philadelphia.

_April 28th_.--James T. Johnston, Esq., of N.Y., writes on the
interesting character of the mineralogy of the interior of Georgia.

The spirit of inquiry denoted by these letters gives but a faint idea
of the interest which was now awakened in the public mind, on the
exploration of the west, and it would require a reference to the public
prints of the day to denote this. If the delay had served no other
purpose, it had brought us into a familiar acquaintance with our
commander, who was frank and straigh