"My command of geometry was tolerably complete, and one way in which I frequently amused myself was by making paper models (most carefully drawn in outline) which were buttoned together without any cement or sewing. Thus I made models, not only of regular solids, regularly irregular solids, cones cut in all directions so as to shew the conic sections, and the like, but also of six-gun batteries, intrenchments and fortresses of various kinds &c. "From various books I had learnt the construction of the steam-engine: the older forms from the Dictionary of Arts and Sciences; newer forms from modern books. The newest form however (with the sliding steam valve) I learnt from a 6-horse engine at Bawtrey's brewery (in which Mr Keeling the father of my schoolfellow had acquired a partnership). I frequently went to look at this engine, and on one occasion had the extreme felicity of examining some of its parts when it was opened for repair. "In the mean time my education was advancing at Playford. The first record, I believe, which I have of my attention to mechanics there is the plan of a threshing-machine which I drew. But I was acquiring valuable information of all kinds from the Encyclopaedia Londinensis, a work which without being high in any respect is one of the most generally useful that I have seen. But I well remember one of the most important steps that I ever made. I had tried experiments with the object-glass of an opera-glass and was greatly astonished at the appearance of the images of objects seen through the glass under different conditions. By these things my thoughts were turned to accurate optics, and I read with care Rutherford's Lectures, which my uncle possessed. The acquisition of an accurate knowledge of the effect of optical constructions was one of the most charming attainments that I ever reached. Long before I went to College I understood the action of the lenses of a telescope better than most opticians. I also read with great zeal Nicholson's Dictionary of Chemistry, and occasionally made chemical experiments of an inexpensive kind: indeed I grew so fond of this subject that there was some thought of apprenticing me to a chemist. I also attended to surveying and made a tolerable survey and map of my uncle's farm.