Tuesday evening, February 19.--Three days have passed since I have written a line for you. This suspension was occasioned by my late hours last night. After spending the morning at the Horticultural Society, then going into the City, where I dined, then going far out on the Mile-End Road to deliver a letter intrusted to me by Mr. Scatcherd, then returning as far as the Bank, I went again, partly by omnibus and partly on my legs, almost as far in the northern outskirts of the town, to spend an evening with Mr. Bowerbank, one of the best microscopists in London, who owns the best microscope. I found so much to see that I did not get away until past twelve, and then I had a walk before me almost the whole length of London,--from New North Road to Charing Cross. I had an opportunity of seeing, what was especially promised me, the camera lucida applied to the microscope; an invaluable invention for an awkward person like me, as I am convinced I could with a very little practice turn out very fair outline sketches of objects I might be examining. I acquired much information on various subjects; saw some most curious and unique specimens of vegetable structure, and particularly of fossil fruits, of which Mr. Bowerbank possesses an invaluable collection; capsules, which we broke open, and examined not only the seed, with its testa, raphe, and funiculus, but even the pulp which surrounded it. I looked at many of his specimens of recent and fossil wood, at his unrivaled cabinet of British fossils, and when our party broke up, there was still so much left that we made an appointment for another evening.... Mr. Bentham, Mr. Brydges, and I went to the Linnæan Society; the president, the Bishop of Norwich, was in the chair,--an amiable old gentleman. Boott, Yarrell, Ward, Royle, Forster, et multis aliis, were present. Mr. Forster[71] invited Dr. Boott and me to fix a day to visit him at his residence, some miles in the country, and dine with him. He is greatly esteemed, and is said to be one of the most kind-hearted and benevolent of men. I am now engaged, I believe, for every day and evening of this week, and half of next, and am busy enough, I assure you....