SPENCER, Herbert, an English philosopher, born in Derby, April 27, 1820. His father was a teacher. Herbert was fond of keeping insects and watching their transformations, and for years the finding and rearing of caterpillars, the catching and preserving of winged insects and making drawings of them, were his regular occupations. He also assisted his father in philosophical experiments. At the age of 13 he was sent to study with his uncle, the Rev. Thomas Spencer, rector of the parish of Hinton. Here he remained three years, and made special progress in mathematics. Returning home, he studied perspective with his father, on the principle of independent discovery, the successive problems being put in such order that he was enabled to find out the solutions himself. This was a favorite mode of teaching with his father, who is the author of a valuable little work entitled “Inventional Geometry,” on this plan. At 16 Herbert devised a new and ingenious theorem in descriptive geometry, which was published with the demonstration in the “Civil Engineers' and Architects' Journal.” At 17 he accepted an engagement under Charles (afterward Sir Charles) Fox as a civil engineer, and began work on the London and Birmingham railway. In 1841 he declined a further appointment, returned home, and spent two years in mathematical and miscellaneous studies. He made a botanical press and a herbarium, and practised drawing and modelling. All the time he had in progress some scheme of invention, improvements in watchmaking, machinery for the manufacture of type by compression of the metal instead of casting, a new form of printing press, and the application of electrotype to engraving, afterward known as the glyptograph. In the spring of 1843 he went to London in quest of literary occupation, but did not succeed, and resumed engineering. His earliest literary contributions were made to the “Civil Engineers' and Architects' Journal,” the “Philosophical Magazine,” the “Zoist,” and the