434 
INDEX. 
Springs (mineral). Analysis of several, 234. 
Standards of linear measure. On errors in them, arising from the thickness of the bar in which 
they are traced, 359. 
Steam-engines in Cornwall. On the progressive improvements made in their efficiency, 121. 
Stomach of the zariffa. Report on, 85. 
T. 
Temperature. Correction for its variations in observations with the invariable pendulum, 251. 
Determination of the higher degrees of temperature by means of a new re- 
gister-pyrometer, 257. 
Thermometer. Its higher degrees estimated by a new register-pyrometer, 257. 
Threads of glass. Their elasticity applied to torsion balances, 215. 
Torsion balance constructed with threads of glass, 215. 
Transparent plates. Action of their second surfaces upon light, 133. 
Twins (Siamese). Account of them, 177. 
V. 
Van Beek (Dr.). His observations on the velocity of sound, 209. 
Veins (metalliferous). Their electro-magnetic properties, 399. 
Velocities (angular). On the methods best adapted for producing the greatest, 121. 
Velocity of sound. On the investigations relative to it, 209. 
Vibrations of the invariable pendulum. Difference in their number at Greenwich and Al- 
tona, 239. 
W. 
Waters (mineral). On the occurrence of iodine and bromine in those of Britain, 223. 
Y. 
Yelloly (John, M.D. F.R.S.). Sequel to a paper on calculous concretions, and the diseases 
to which they give rise, 415. 
Z. 
Zariffa. Report on its stomach, 85. 
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