[ i 088 ] 
Pinion, Account of the advantages of a newly-invented machine much varied in 
its effects, and very ufeful for determining the perfect proportion between different 
moveables aCting by levers, and wheel, and pinion, p, 950 — 998. 
PiJJol loaded with inflammable air, fired by a very moderate eleCtrical fpark, p. 1025, 
1026. 
Planets , concerning their mean denfities, p. 784. 
Plant, A defcription of the wonderful plant of Sotnbrero, p. 178. 
Plants have a different property in them in their growing and gathered dates, p. 209, 
210. 
Plafer ufed in fecuring buildings againfl fire, how prepared, p. 887, 888. 
Playfair , Rev. Mr. John, on the arithmetic of impoflible quantities, p. 318— 343. 
Points at the upper terminations of conductors to fecure houfes, &c. from lightning, 
more ufeful than balls, p. 155 — 159, Rounded conductors fecure buildings againft 
the effects of lightning better than pointed ones, p. 245, &c. Pointed conductors 
recommended as the mofl effectual for this purpofe, p. 314 — 317. Inquiry whether 
fliarp or blunt conductors are the fitted: to preferve buildings from lightning, 
p, 801 — 820. Experiments on electricity, being an attempt to (hew the advantage 
of elevated pointed conductors, p. 823 — 853. Remarks on Mr. Wilfon’s experi- 
ments on the nature and ufe of conductors, p. 855 — 860. New experiments on the 
Leyden phial refpeCtlng the termination of conductors, p. 999 — ion. 
Polbill, Nathaniel, efq. his letter on Mr. Debraw’s improvements in the culture of 
bees, p. 107 — no. 
Polygamy allowed among the Battas in Sumatra, p. 166, They purchafe their wives, 
and all live in the fame houfe, p. i65, 167. See Sumatra, 
Population . Obfervations on the population and difeafes of Cheder in the year 1774, 
p. 13 1. See Chefer, 
Ponta del Guda , a city in the ifland of St. Miguel, fome account of it, and of the 
country round it, p. 602, 603. 
Powder, magazines of, concerning fecuring them from lightning, p.155 — 159. See 
Magazines, 
Primrofe, Tree primrofe flowers, their effeCt upon air, p. 202. 
Pringle , Sir John, his remark for avoiding difeafes in cantonments in marfhy grounds, 
p. 217. 
Prifoners killed and eaten by the Battas in Sumatra, p. 166. 
Privy, experiments on air taken from within one, p. 201. 
Propagation of fpecies, requires the greated powers of heat an animal can exert, p. 31* 
Proportion Compafs, Account of the advantages of a newly-invented machine much 
varied in its effeCls, and very ufeful for determining the perfeCt proportion between 
different moveables aCting by levers, and wheel, and pinion, p. 950 — 998. 
Pulteney , Dr. Richard, his account of baptifms, marriages, and burials, during forty 
years, in the parilh of Blandford Forum, Dorfet, p. 615. See Blandford Forum, 
2 Purfket ♦ 
