INDEX. 
511 
S. 
Sabine (Captain Edward, R.A.). Experiments on the length of the seconds pendulum at 
the Royal Observatory at Greenwich, 459. 
Screens , on their influence in arresting the progress of magnetic action, 497. 
Seconds ■pendulum at the Royal Observatory at Greenwich , experiments on the length of, 
459. 
Sidereal objects , steadiness of one, remarkably contrasted with the unsteadiness of another 
seen under similar circumstances of atmosphere and altitude, 419. 
South (Sir James). On the extensive atmosphere of Mars, 417. 
Suspension bridges , table for facilitating the computations relative to, 341. 
T. 
Telescopes (Jluid refracting ), on, 9. 
advantages of sulphuret of carbon over glass, in the construction of, 12. 
principal change proposed to be made in the construction of a very large one, 14. 
Thames, difference of level of, between London Bridge and the sea, &c. 1 67. 
Thetis (His Majesty’s ship), remarks on the loss of, 218. 
Tide-gauge (Lloyd’s), description of, 174. 
Tides and winds, graphical registrer of, 209. 
Tides in the port of London, on the, 379. 
V. 
Vessels, errors in the course of, occasioned by local attraction, 215. 
Vibrating surfaces, on the peculiar arrangement and motions of the heaps formed by par- 
ticles lying on, 315. 
— on the forms and states assumed by fluids in contact with, 319. 
crispated appearance of a stratum of water on, 319. 
— similar appearances shown by other fluids, 322. 
3 u 
MDCCCXXXI. 
