. C 453 3 
Bills of Mortality. See While , York. Their importance to the community, p. 3 
Births and burials. See York. 
Black , Dr. See Phlogifon. 
Bradley , Dr. See Velocity of the Rays of Light, Fixed Stars. Part of a letter from him 
to Dr. Halley, on a new difeovered motion of the fixed liars, p. 84. 
Brook , Abraham. See Elettromcter. 
C. 
• % 0 > Lf 
Calcareous earth. See Saline Subfances. 
Canton , Mr. See Eledlricity. 
Cwvendijh , Lord Charles. See Thermometer. 
Collifion of Bodies. Mr. Smeaton’s new fundamental experiments upon, p. 357. 
Intended as a fupplement to his tradl on mechanic power, p. 338. Reafon for now 
putluing the fame fubjedl, ibid. The laws of collifion are principally of three kinds, 
p. 338. Confiderations on two bodies, equal in weight or quantity of matter, ftriking 
one another, p. 339. et feq. Defcription of the machine for collifion, p. 347. For 
trials on elaftic bodies, p. 349. For trials on non-elaflic foft bodies, p. 350. 
Colours. See Fire. All eyes or lights are not equally adapted for diftinguifhing them, 
p. 308. 
Cornijh porcelain clays. See Fire. 
Crelliiy D. Laurentii. Nova experimenta chemica qua: ad penitiorem acidi e pingue- 
dine eruti cognitionem vajere videntur, p. 8 — 34. 
D. .»■■■■•.' r - - 
Be la Lande. See Fixed Stars. 
Double Jlars. See Fixed Stars. Steps of vifion preparatory to viewing double liars, p. 
100. See Te/efcopes. Catalogue of double Pars, by Mr. Herfchel, p. 1 1 2. Intro- 
ductory remarks, ibid. The general diilribution of the fubjedl, with terms ufed to 
exprefs the comparative fizes, and obfervations on the colours of liars, ibid. p. 113. 
Someparticular terms and contradions explained, p. 1 14. Firfi clafs of double liars, 
p. X15. Second ditto, P . 122. Third ditto, p. 129. Fourth ditto, p. 136. Fifth 
ditto, p. 14,. Sixth ditto, p. i s o. Poflfcripr, p. 157. Mr. Mayer, in his “ Dc 
“ novis in ccelo fidereo phanomenis,” has given a pretty large lift of double ftars, 
fome of them the fame with thofe in Mr. Herfchel’s catalogue, ibid. Mr. Herfchel’s 
reafon for ufing glalTes with much higher powers than thofe ufed by Mr. Mayer, p. 
J58. Neither Mr. D. Mayer’s inftruments, nor his method, were adequate to his 
purpofe, ibid. Difference between Mr. Mayer’s calculation and Mr. Herfchel’s 
accounted 04 p. 159. Reafons for uling the txpreflion double far in a few irfftances 
preferably to Comes, Companion , or Satellite, p. 161. 
Doubts, See Herjchcl. 
Earth 
