INDEX. 
Vision , single with two eyes arises from structure of the optic nerves, 
not from habit, 229. 
— — — singular phenomenon of, observed in viewing very faint 
stars, iii. 15, 16. 
Vivian, T. Esq. sends copper to Mr. Faraday for analysis. 
W 
Walrus , Sir E. Home on, 233 — structure of its hind feet, 234 — 
mode of supplying its duodenum with bile, 235— Feeds on sea- 
weed, 236. 
Wind, its effect in altering the velocity of sound, 425. 
Winter birds of passage, 30. 
Wollaston, W. H. M. D. V. P R. S. on semi-decussation of the 
optic nerves, 222 — on apparent direction of eyes in a portrait, 
247 — does not depend on the circularity of the iris, 248, 
Worm (Earth,) brain of, 10, Plate II. 
Y 
Young, T., M. D. For. Sec. R. S. on a finite expression for refrac- 
tion in an atmosphere nearly resembling the earth’s, 159. 
Z 
Zevenboompjes , one of the stations chosen by Moll and Van Beek, 
for experiments on velocity of sound, 428. 
Zinc, its electro-mechanical effect in alloy with mercury, 182— 
sensible when only a 1200000th part of the alloy, 183 — contact 
of mercury with, momentary— its effect, 195. 
ERRATUM. 
The references to the Figures in Mr. Ivory’s Paper having been accidentally 
omitted, are to be thus supplied ; 
Fig. I — page ioo. 
Fig. 2 — Prop, i — page m. 
Fig. 3 — Prop. 2 — page 115. 
From the Press of 
IV.NICOL, 
Cleveland-row, St. James’s, London. 
