ove letter were embodied by Prof. Owen in the section "On
the Use of the Microscope on Board Ship," forming part of the article
"Zoology" in the "Manual of Scientific Enquiry, Prepared for the Use of
Her Majesty's Navy" (London, 1849).), but I have derived such infinitely
great advantage from my new simple microscope, in comparison with the
one which I used on board the "Beagle," and which was recommended to me
by R. Brown ("Life and Letters," I., page 145.), that I cannot forego
the mere chance of advantage of urging this on you. The leading point
of difference consists simply in having the stage for saucers very large
and fixed. Mine will hold a saucer three inches in inside diameter.
I have never seen such a microscope as mine, though Chevalier's (from
whose plan many points of mine are taken), of Paris, approaches it
pretty closely. I fully appreciate the utter ABSURDITY of my giving
you advice about means of dissecting; but I have appreciated myself the
enormous disadvantage of having worked with a bad instrument, though
thought a few years since the best. Please to observe that without you
call especial attention to this point, those ignorant of Natural History
will be sure to get one of the fiddling instruments sold in shops.
If you thought fit, I would point out the differences, which, from my
experience, make a useful microscope for the kind of dissection of
the invertebrates which a person would be likely to attempt on board a
vessel. But pray again believe that I feel the absurdity of this letter,
and I write merely from the chance of yourself, possessing great skill
and having worked with good instruments, [not being] possibly fully
aware what an astonishing difference the kind of microscope makes for
those who have not been trained in skill for dissection under water.
When next I come to town (I was prevented last time by illness) I must
call on you, and report, for my own satisfaction, a really (I think)
curious point I have made out in my beloved barnacles. You cannot tell
how much I enjoyed my talk with you here.

Ever, my dear Owen, Yours sincerely, C. DARWIN.

P.S.--If I do not hear, I shall understand that my letter is
superfluous. Smith and Beck were so pleased with the simple microscope
they made for me, that they have made another as a model. If you are
consulted by any young naturalists, do recommend them to look at this.
I really feel quite a personal gratitude to this form of microscope, and
qu