INDEX. 
page 
Pendulum , on its use as a standard of measure, - 133, 174 
Placenta, account of a tumour found therein, - - 361 
Porisms , - - - - 37$ 
Presents received by the Royal Society, from November, 1707, 
to June, 1798, - - - - 595 
PreVost, P. Quelques remarques d’optique, principalement rela- 
tives a la reflexibilite des rayons de la lumiere, - - 31 1 
Provisions , on the prices of them at different periods, - 175 
Pyrites y remarks on its formation, - 580* 
R 
Rabbity on a calculus from one, - - - 42 
Rafw, register of, at Lyndon, in Rutland, - - 130 
Re flexibility of Light, remarks on, - - - gj 1 
Refraction, atmospherical, singular instance of, \ - - 357 
Resistance of bodies moving in fluids , experiments on, - 1 
Retina of the Eye, account of an orifice therein, - 332 
Roman foot, on the length of, - - 169 
Roots of equations, observations on, - - 369 
Ruby , specific gravity of, - - - 416, 447 
Rum ford, Benjamin Count of. An inquiry concerning the 
source of the heat which is excited by friction, - - 80 
■— ■ An inquiry concerning the 
chemical properties that have been attributed to light, - 449 
S 
Saint Helena , diurnal variation of the magnetic needle in that island, 397 
Sanscrita manuscripts , catalogue of, - - 5 82 
Sapphire , specific gravity of, - 416, 445 
Satellites of the Georgium Sidus. See Georgium Sidus . 
Series , slowly converging , new method of computing the value 
of one, ----- 183 
- .... method of obtaining the sums of many 
which arise in the fluents of binomial surds, - - 547 
— — — swiftly converging , method of obtaining, useful in com- 
puting the perturbations of the Earth, Mars, and Venus, - 527 
Ships, disquisition on their stability, - - - 201 
Silver , effect of the Mere of Diss upon it, - - 57 B 
oxide of ‘ experiments on its reduction, - 460, 465 
— — coin , method used by those who diminish it, - 573 
