Page 72 line 4 for EI, read FI.
—— 103 — 30 — depend, read depends.
—— 135 — 10 — refacting, read refracting.
—— 136 — 10 — colour, read colours.
—— 146 — 27 — G, read C.
—— 146 — 32 — prisms, read prism.
—— 153 — 35 — 28_° 3´, read 28° 10´
—— 165 — 32 — some, read since.
—— 165 — 33 dele that.
—— 166 — 5 for these, read their.
—— 166 — 21 — those, read their.
—— 178 — 32 — variety, read vanity.
—— 187 — 7 — in, read an.
—— 187 — 11 — (p. 103.), read (p. 72.)
—— 189 — 30 — lens, read lenses.
—— 199 — 31 — punice, read pumice.
—— 216 — 10 — nine, read ten.
—— 236 — 12, 13 — “more distant from,” read “nearer to.”
—— 337 — 27 — 1, read 1½.