Illustration: FIG. 82.--Principle of Newtonian reflector.]

"And then, to my sorrow, I saw almost every room turned into a
workshop. A cabinet-maker making a tube and stands of all
descriptions in a handsomely furnished drawing-room; Alex. putting
up a huge turning-machine (which he had brought in the autumn from
Bristol, where he used to spend the summer) in a bed-room, for
turning patterns, grinding glasses, and turning eye-pieces, &c. At
the same time music durst not lie entirely dormant during the
summer, and my brother had frequent rehearsals at home."

Finally, in 1774, at the age of thirty-six, he had made himself a
5-1/2-foot telescope, and began to view the heavens. So attached was he
to the instrument that he would run from the concert-room between the
parts, and take a look at the stars.

He soon began another telescope, and then another. He must have made
some dozen different telescopes, always trying to get them bigger and
bigger; at last he got a 7-foot and then a 10-foot instrument, and began
a systematic survey of the heavens; he also began to communicate his
results to the Royal Society.

He now took a larger house, with more room for workshops, and a grass
plot for a 20-foot telescope, and still he went on grinding
mirrors--literally hundreds of them.

I read another extract from the diary of his sister, who waited on him
and obeyed him like a spaniel:--

"My time was taken up with copying music and practising, besides
attendance on my brother when polishing, since by way of keeping
him alive I was constantly obliged to feed him by putting the
victuals by bits into his mouth. This was once the case when, in
order to finish a 7-foot mirror, he had not taken his hands from it
for sixteen hours together. In general he was never unemployed at
meals, but was always at those times contriving or making drawings
of whatever came in his mind. Generally I was obliged to read to
him whilst he was at the turning-lathe, or polishing mirrors--_Don
Quixote_, _Arabian Nights' Entertainments_, the novels of Sterne,
Fielding, &c.; serving tea and supper without interrupting the work
with which he was engaged, ... and sometimes lending a hand. I
became, in time, as useful a member of the workshop as a boy might
be to his master in the first year of his apprenticeship.... But as
I was to take a part the