INDEX. 
431 
F. 
Fallows (Rev. Fearon, F.R.S.). Observations with the invariable pendulum at the Royal 
Observatory Cape of Good Hope, for the purpose of determining the compression of 
the earth, 153. 
Faraday (Michael, Esq. F.R.S.). Bakerian lecture on the manufacture of glass for 
optical purposes, 1. 
Farquharson (Rev. James, F.R.S.). On the influence of the Aurora Borealis on the 
magnetic needle, 97. 
Fox (Robert Were). On the electro-magnetic properties of metalliferous veins in the 
mines of Cornwall, 399. 
N 
G. 
Galvanometer. Description of the one employed to detect the electro-magnetic properties 
of metalliferous veins in the Cornish mines, 399. 
Gilbert (Davies, Esq. P.R.S.). On the progressive improvements made in the efficiency 
of steam-engines in Cornwall ; with investigations of the methods best adapted for im- 
parting great angular velocities, 121. 
Glass. On the manufacture of glass for optical purposes, 1. 
On the elasticity of threads of glass, with some of the most useful applications of 
this property to torsion balances, 215. 
Greenwich and Altona ( Royal Observatories at). Difference in the number of vibrations 
made by an invariable pendulum at these two places, 239. 
Guyton de Morveau (M.). Observations on his proposal for a pyrometer, 257. 
H. 
Hansteen (Professor). His announcement of the existence of a second magnetic pole 
within the arctic circle, 407. 
Home (Sir Evf.rard, Bart. V.P.R.S.). Report on the stomach of the zariffa, 85. 
Horsburgh (Capt. James). Remarks on several icebergs met with in unusually low 
southern latitudes, 117. 
I. 
Icebergs in low southern latitudes, 117. 
Illumination of light-houses, 383. 
Imperial standard yard, 364. 
Iodine. On its occurrence in certain mineral waters of South Britain, 223. 
Isthmus of Panama. Level of the Pacific Ocean relative to that of the Atlantic, 59. 
K. 
Kater (Capt. Henry, V.P.R.S.). On the error in standards of linear measure, arising 
from the thickness of the bar in which they are traced, 359. 
3 K 
MDCCCXXX. 
