traced the lines of the quadrant.

"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