THE printing of Faraday's diary pursues its stately and regular course, and two further volumes are before us covering a productive period of eleven years-from the summer of 1836 to the summer of 1847. Once again we are privileged to toil after the amazingly versatile processes of Faraday's mind. It is the story of much less than a decade which is compressed into some nine hundred printed pages if we bear in mind that the diary is a significant blank between September 1840 and June 1842, and between February 1843 and February 1844. Moreover, when we remember the comparative paucity of the resources at Faraday's disposal and his propensity-indeed a necessity of his nature-to do everything for himself, so that it was impossible for him to depute work of even minor responsibility to a student or assistant, we feel that we have surveyed a record of single-handed achievement of which any great school of research might be legitimately proud. Think of it; Cavendish had, years before, measured specific inductive capacities entirely for his own satisfaction and, more suo, had left his results unpublished and unknown to his and to Faraday's generation. It was Faraday's part in this period to rediscover this property and to make those measurements which are quoted and misquoted in most elementary textbooks. Here, too, we find the story of the liquefaction and solidification of various gases by compression and cooling in closed tubes. Faraday's Diary: being the various Philosophical Notes of Experimental Investigation made by Michael Faraday, D.C.L., F.R.S., during the Years 1820–1862 and bequeathed by him to the Royal Institution of Great Britain, Now, by order of the Managers, printed and published for the first time, under the editorial supervision of Thomas Martin. Vol. 3: May 26, 1836–Nov. 9, 1839. Pp. xii + 466. Vol. 4: Nov. 12, 1839–June 26, 1847. Pp. xii + 448. (London: G. Bell and Sons, Ltd., 1933.) 7 vols., £12 12s. 0d. net.