instructions are sent in; but even if they are not sent in, I daresay what I am going to write will be absolutely superfluous (25/1.

The results of Mr.Darwin's experience given in the above 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.