Page 158: 'eyepiece' corrected to 'eye-piece', to match all the rest.
"... and a single lens eye-piece giving a power of 36."
Page 194: The code for the astronomical symbol for Uranus is U+26E2 or ⛢ (& # 9954;), but it does not seem to work, except, perhaps, in the very latest browsers) so an image has been used instead:
Page 205: removed extraneous 'of'.
"The nucleus is the only part of [of] a comet's structure "
Page 209: 'unconsidreed' corrected to 'unconsidered'.
"... that some unconsidered little patch of haze...."
Page 240: 'Ursae' corrected to 'Ursæ' to match entries in the Index, and for consistency.
"... though Riccioli detected the duplicity of Zeta Ursæ Majoris (Mizar), in 1650,..."