science; what follows suggests a caution, to which Darwin afterwards drew more particular attention, though he turned the weapon against Lyell himself, viz. "the imperfection of the geological record." A letter to his father, also written in the month of April, shows that, while he has an immediate purpose of opening fire on MacCulloch,[16] who had bitterly attacked in the _Westminster Review_ Scrope's book upon Volcanoes, he has "come to the conclusion that something of a more scientific character is wanted, for which the pages of a periodical are not fitted." He might, he says, write an elementary book, like Mrs. Marcet's "Conversations on Chemistry," but something on a much larger scale evidently is floating on his mind. In this letter also he discusses his prospects with his father, who apparently had suggested that he should cease from going on circuit; and argues that he gains time by appearing to be engaged in a profession, for "friends have no mercy on the man who is supposed to have some leisure time, and heap upon him all kinds of unremunerative duties." Lyell was not devoid of Scotch shrewdness, and doubtless early learnt that when it is all work and no pay men see your merits through a magnifying glass, but when it comes to the question of a reward, they shift the instrument to your defects. Gradually the plan of the future book assumed a more definite shape in his mind, as we can see from a letter to Dr. Mantell early in 1828. About this time also Murchison, with whom he was planning a long visit to Auvergne,[17] appears among his correspondents. Herschel[18] tells him how he and Faraday had melted in a furnace "granite into a slag-like lava"; Hooker[19] begs him to notice the connection between plants and soils as he travels; his father urges him to take his clerk with him to act as amanuensis and save his eyes, which might be affected by the glare of the sun, and to help him generally in collecting specimens and carrying the barometers. Early in the month of May he started for Paris, where he met Mr. and Mrs. Murchison, and the party left for Clermont Ferrand in a "light open carriage, with post horses." As far as Moulins the roads were bad, but as they receded from Paris and approached the mountains "the roads and the rates of posting improved, so that we averaged nine miles an hour, and the change of horses [was] almost as quick as in England. The politeness of the people has much delighted us, and they are so intelligent that we get much geology from them." Clermont Ferrand became their headquarters for some time, and Lyell's letters to his father are full of notes on the geology of the district, one of the most interesting in Europe. The great plateau which rises on the western side of the broad valley of the Allier is studded with cones and craters--some so fresh that one might imagine their last eruptions to have happened during the decline of the Roman empire;[20] others in