INDEX. 
Q 
Quadratrices, a class of curves expressing the apparent form of the 
spokes of a revolving wheel, seen through vertical apertures, 
138 — their general equation, 139. 
/ R 
Radiant hesit, terrestrial, Mr. Powell on, 187. 
Reptile, fossil, a new species of described, 179. 
Retina, its retention of impressions applied to explain an optical 
deception, 135. 
Rhomboid, in crystallography, theory of its modifications, 89. 
Ritchie, Revd. W., on a new photometer, with its applica- 
tion, &c. 141. 146. 
Roget, P. M., M.D. F. R. S., his explanation of an optical decep- 
tion in the appearance of the spokes of a revolving wheel, &c. 
131. 140. 
Rotation, its effect in developing magnetic effects. See Magnetism, 
S 
Sandstone of Tilgate forest, fossil remains of the Iguanodon found 
in, 179. 
Screens of glass, their effect in intercepting terrestrial heat, 187. 
Secondary faces of crystals, theory of their arrangement, 121. 
Shells, fossil, in peat marl in Ireland, list of, 432. 
Ships, protection of their copper by iron, 340 — instanced in the 
cases of the Sammarang, Elizabeth, Carnebrea Castle, Howe, 
and others, 342, 3. 
Solutions, alkaline, their effect in altering or subverting the electro- 
chemical relation between protected and protecting metals. 
Stars, fixed, Mr. Pond on their annual variations, 510. 
T 
Tables, Mr. Gompertz’s, for computing life contingencies, 547. 
Tadpole, progress of its formation in ovo, 81, Plate XXVII. 
Temperature, its influence on the intensity of magnetic forces, 
Mr. Christie on, 1. 
Terrestrial magnetic intensity, its diurnal variation, Mr. Christie 
on, 1. 
Tetrahedron, in crystallography, theory of its modifications, 106. 
Tilgate forest. See Sandstone. 
Trachece of insects, their structure, 234 — of the mole cricket, id. — 
their supposed office, 235. 
