GENERAL INDEX. 



Pole of a magnet tends to induce opposite polarity in adja- 

 cent bodies ........ 



sometimes reversed by lightning 



Polishing of lenses and specula, method of ... 

 Polyzonal lenses described ..... 



PORT A said to have invented the camera obscura 

 Forter, its taste when drunk out of a pewter pot . 

 Positive and negative electricity, concerning 

 Power of a magnet at 100 Fahrenheit increases as it cools 

 lost by rubbing .... 



of a galvanic battery best determined by experiment 

 Powers, mechanical, individually described 

 Precautions in constructing thermometers . 

 Preservation of magnetic power, means for ... 

 Pressure of fluids, action of explained 



of the atmosphere on a man's body, amount of 

 PIIEVOST'S theory of magnetic fluids .... 



Primary colours of the rays of light . 



Prisms, refraction of the rays of light through 



Prismatic spectrum, arrangement of ... 



observed by Seneca 

 phenomenon, singular account of . 

 colours, exhibited in the combustion of metals 

 . . . exist in the light, and are not produced by 



the prism ........ 



PR IT CHARD'S diamond and sapphire lenses, account of 

 Progress of magnetic induction, method of quickening . 



by heat, remarks on 



Progressive changes of dip and variation of the magnetic needle 

 Properties of bodies in general ..... 



mechanical, of atmospheric air ... 



of fluid " 



PTOLEMY, his knowledge of the laws of refraction . . 



Pulley, the principle of, illustrated ..... 



Pump, common, principle and construction of 



forcing ... .... 



. . air, description of, and experiments with 

 Pyrometer, history and construction of various kinds 



by Achard described ... 



by Muschenbrock ..... 



by Desagulier ..... 



by Ellicot ....... 



Mortimer's ...... 



Froteringham's . 



Smeaton's ...... 



Ferguson's ...... 



Microscopic, of De Luc .... 



Ramsden's ....... 



Wedgewood's ...... 



Platina one, of Morveau .... 



Schmidt's air-pyrometer 

 dell 



It's, or metalline thermometer 

 Js, or metalline thermometer 

 Pyroscope, by tes^, described 



ELECT. MAGN. 

 OPT. IN ST. 



NEW. OPT. 

 GALV. 

 ELECT. 

 MAON. 



GALV. . 

 POP. INT. 

 THERM. 

 MAGN. 

 POP. INT. 



MAGN. 



. NEW. OPT. . 

 POP. INT. 90, NEW. OPT. 

 91, 



NEW. OPT. 

 GALV. . 



POP. INT. 



OPT. INST. 

 MAGN. 



POP. INT. 



NEW. OPT. 

 POP. INT. 



THERM. 



01 uiiiiu t a 



.niell's 

 . . '''''. ' l > i 



QUERIES, Newton's, concerning the inflexion of light * NEW. OPT, 



e\r, and vapours, distinguished, and theif causes 



1 out . . . . . POP. INT. 



o\r, and hail . ... 



. the phenomena of investigated by Aristotle and 



different theories of 

 s reflecting telescope, description of 

 s 's micrometrical eye-pieces described . 



microscopic pyrometer .. 



gkt proceed in straight lines .. 



primary colours of , f . 



NEW. OPT. 

 OPT. INST. 



37 

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88 

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30, 31 

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3 

 24 

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 13 

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2029 



1015 

 53 



57,58 



65 



41 



15,33 



1231 



15 



1 



38 



1113 



90 

 13 

 11 



. 12 



2931 



18 



. 7 



5660 



2,3 



24, 26 



67,68 



m 



65, 66 



1532 



9, 10 



15 



16 



16, 17 

 17 

 81 



1820 



2123 



23,24 



24^27 



2729 



2930 



31 



31, 32 



32, 33 

 33 



44, 45 



63 



5 

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