n the aboriginal
tribes to be contributed by General Cass.

A difficulty is, however, denoted. "My duties here," he writes, "as they
engross everything at present, will force me to delay a little, and I am
in hopes, by so doing, to obtain some further data. I enter, in a few
days, on the discharge of my professional duties, under considerable
disadvantages, owing to the late introduction into our courses of some
French works on the highest branches of mathematics, which it falls to
my lot first to teach. Between French, therefore, and fluxions, and
moreover, the _French method of fluxions_, which is somewhat peculiar, I
have had my hands pretty full. I look forward to a respite in April."

The professor had, in fact, to teach his class as he taught himself, and
just kept ahead of them--a very hard task.

In the mean time, while this plan of an enlarged publication was kept in
view, I pushed my narrative forward. While it was going through the
press, almost every mail brought me something of interest respecting the
progress of scientific discovery. A few items may be noticed.

_Discovery of Strontian on Lake Erie_.--Mr. William A. Bird, of Troy, of
the Boundary Survey, writes (Jan. 22d):--

"On our return down the lake, last fall, we were becalmed near the
islands in Lake Erie. I took a boat, and, accompanied by Major
Delafield, Mr. A. Stevenson, and Mr. De Russey (who was to be our
guide), went in search of the strontian to the _main_ shore, where Mr.
De Russey says it was found in the summer of 1819. After an unsuccessful
search of an hour, we gave it up, and determined to return to our
vessel. On our way we stopped at Moss Island, when, immediately on
landing, we found the mineral in question. I wandered a little from the
others, and found the large bed of which I spoke to you. We there
procured large quantities, and some large crystals.

"This strontian was on the south side of Moss Island, in a horizontal
vein of three feet in thickness, and from forty to fifty feet in
length. I had no means of judging its depth into the rock. The base of
the island is wholly composed of limestone, in which shells scarcely, if
ever, appear."

_Conchology--Mineralized Fungus, &c._--Dr. Samuel L. Mitchell, of New
York, writes (Jan. 30th): "I was glad to receive your letter and the
accompanying articles, by the hand of Colonel Gardiner; but I am sorry
your business is such as to prevent your meditated visit to the city
until sp