INDEX. 
Pendulum , its length (39 - 13929) in British inches, p. 1. Its 
length at Unst and Leith Fort, 2. 
— invariable. Lieut. Foster’s observations of at Port 
Bowen, Part IV. No. 2. 
- Capt. Sabine’s observations employed to deduce the 
figure and ellipticity of the earth, 564. 
Perkins, Jacob, Esq. on the compression of water by high degrees 
of force, 541. 
Pholas, its mode of boring explained, 353. 
Piezometer for measuring the compression of water described, 542 
Pile , voltaic , its action increased, suspended, or reversed, by the 
temporary action of a stronger pile, of which it forms a part, 412 
Piles , secondary, of Ritter, explained, 413. 
Poison of the common toad, Dr. J. Davy on, 12T. 
Pole Star, its transits employed to detect instrumental derange- 
ments by the sun’s heat, 440. 
Port Bowen , observations at by Capt. Parry and Lieut. Foster, 
Ross, &c. Part IV. See Foster. 
Pounds, Troy and Avoirdupois, legally defined, 8. 
Powell, Revd. B. on the radiation of heat through glass screens, 
372. 
Price, Dr. an error in his calculation of the amount of compound 
interest pointed out, 297. 
Protection of ship’s copper, 420 — of steam boilers, 421. 
Pupil, artificial, case of blindness from birth removed by forming, 
Ram, hydraulic, its action expressed in Mr. Babbage’s notation, 
264. 
Radiation of heat through glass screens, Mr. Powell’s experi- 
ments on, 372. 
Reflexion of the sun’s rays employed as a geodsetic signal, 327. 
Refraction, atmospheric, at Port Bowen, Part IV. No. 9. 
Retina, its sensibility retained after 45 years inaction, 529. 
Ritchie, Mr., his experiments on radiation of heat through thin 
glass considered, 380. 
Rocket signals used for determining differences of longitude, 78. 
Rotations, electric and magnetic, Mr, Babbage on, 494. 
■ of electrified bodies over glass, 497. 
causes of in suspended needles examined, 520. 
