Meantime, tired of smoky London, Darwin purchased a home in Down, a retired village five or six hundred feet above the sea. The house was a square brick building, of three stories, vine-covered, in the midst of eighteen acres. "Its chief merit," Darwin writes to a friend, "is its extreme rurality. I think I was never in a more perfectly quiet country." Here, for forty years, Darwin lived the isolated life of a student, producing the books that made him the most noted scientist of his century. Of these years, Mr. Darwin said: "Few persons can have lived a more retired life than we have done. Besides short visits to the houses of relations, and occasionally to the seaside or elsewhere, we have gone nowhere. During the first part of our residence we went a little into society, and received a few friends here; but my health almost always suffered from the excitement.... I have, therefore, been compelled for many years to give up all dinner parties.... From the same cause I have been able to invite here very few scientific acquaintances. My chief enjoyment and sole employment throughout life has been scientific work; and the excitement from such work makes me for the time forget, or drives quite away, my daily discomfort." At Down, Darwin worked for eight years on two large volumes concerning cirripedia (barnacles), describing all the known living species; the extinct species, or fossil cirripedes, were in two smaller volumes. The first books were published by the Ray Society, between 1851 and 1854; the others by the Palæontographical Society. About two years out of the eight were lost through illness. Sometimes he became half discouraged. He wrote a friend, "I have been so steadily going downhill, I cannot help doubting whether I can ever crawl a little uphill again. Unless I can, enough to work a little, I hope my life may be very short, for to lie on a sofa all day and do nothing but give trouble to the best and kindest of wives and good, dear children is dreadful." Darwin doubted, in after life, "whether the work was worth the consumption of so much time," but Professor Huxley thinks he "never did a wiser thing than when he devoted himself to the years of patient toil which the cirriped-book cost him.... The value of the cirriped monograph lies not merely in the fact that it is a very admirable piece of work, and constituted a great addition to positive knowledge, but still more in the circumstance that it was a piece of critical self-discipline, the effect of which manifested itself in everything he wrote afterwards, and saved him from endless errors of detail." Darwin's patient labor is shown by his working "for the last half-month, daily, in dissecting a little animal about the size of a pin's head, from the Chonos archipelago, and I could spend another month, and daily see more beautiful structure."