INDEX. 413 



Refractions, astronomical, in an atmosphere of dry air, 195; in an atmosphere of air mixed with 



aqueous vapour, 199; comparison of tables of, 224; new table of, 227. 

 Refractive indices, comparison of observed, with the results of theory, 70. 

 Retinacula, the, 324 ; of Mammals compared with the membrana chalazifera and chalazae of 



Birds, 328. 

 RiGO (Robert, Esq.)- An experimental inquiry into the influence of nitrogen on the growth of 



plants, 395. 

 On the evolution of nitrogen during the growth of plants, and the sources 



whence they derive that element, 403. 



S. 



Shell, turbinated, determination of the area and centre of gravity of its surface, and the volume 

 and centre of gravity of its contained solid, 368 ; determination of the polar equation to its 

 surface, 370 ; and of the constant angle of the spiral affected by any given shell, 370. 



Shells {turbinated and discoid), on the geometrical forms of, S5\. 



Spark (electric), 105. 



Spiral, logarithmic, the form affected by the opercula of turbinated shells, S52 ; and by these 

 shells, Sb5, 



Stereoscope, an instrument for the investigation of the phenomena of binocular vision, 375. 



T. 



Tide-gauge, description of a new, 249. 



observations, method of discussing those of Bristol, 233. 



Tide phenomena, questions respecting, with answers supplied by results of observation: I. To 

 which transit of the moon ought the tide to be referred ? 2SQ ; II. How does a change of the 

 epoch affect, 1st, the semimenstrual inequalities ? 237; III. 2nd, the (lunar) parallax correc- 

 tion of the time ? 238 ; IV. 3rd, the (lunar) declination correction of the times ? 2S9 ; V. 4th, 

 the parallax correction of height ? 240 ; VI. 5th, the declination correction of the heights ? 

 241 ; VII. Does the parallax correction of the height vary as the parallax? 241 ; VIII. Does 

 the parallax correction of the time vary as the parallax ? 242 ; IX. Does the declination cor- 

 rection of heights vary as the square of the declination? 242; X. Does the declination cor- 

 rection of the times vary as the square of the declination ? 243 ; XI. Can the laws of the cor- 

 rections be deduced from a single year? 243; XII. Are there any regular differences 

 between the corrections of successive years ? 244 ; XIII. Do the corrections at different 

 places agree in laws and amount ? 245. 



Tides, researches on the. Ninth series. On the determination of the laws of the tides from short 

 series of observations, 231. 



Transverse force of electric current, 165. 



Tunica granulosa, a granulous tunic of Mammalia not hitherto described, 321 ; compared with the 

 membrana chalazifera of Birds, 328. 



V. 



Vacuum, relations of a, to electrical phenomena, 154. 



Vision, contributions to the physiology of. Part the first. On some remarkable and hitherto 

 unobserved phenomena of binocular vision, 371. 



