INDEX. 



603 



Nollet, 585 ; b. 1700, d. 1770. 



Nonconductors, 513. 



Noria, 250, PI. 22. 



North, 398. 



Northern crown, 395. 



Northern hemisphere warmer, 549. 



North pole, 533. 



Norwood, 460. 



Notes of music, 309. 



Nucleus of a comet, 407. 



Numa, 580. 



Number of the stars, 389. 



Nut, 55, PI. 5. 



Nutation, 402. 



Nutation of the earth's axis, 402, 412. 



Nutrition of animals, 577. 



Oblique float boards, 246, 247. 



Oblique forces, PI. 3. 



Oblique impulse of fluids, 230. 



Oblique reflection, 342. 



Obliquity of the ecliptic, 412, 454. 



Observatory, 114. 



Observatory of Greenwich, 150, 4GO. 



Octave, 307. 



Octant, PI. 35. 



Ocular spectra, 357, PI. 30. 



Oersted, 539. 



Oil mill, 170. 



Oil paintings, 73. 



Oil spreading on water, 479. 



Oily substances, 163. 



Olbers, 404, 462. 



Opposition, 418. 



Opposition of forces, PI. 3. 



Optical centre, 327, 352. 



Optical instruments, 328. 



Optic nerve, 351. 



Optics, 195, 196, 320. 



Optometer, 354. 



Orbit of the sun, 398. 



Orbits of comets, 414. 



Orders of architecture, 12?. 



Orders of plants, 572. 



Organ, 314, 316. 



Organ pipes, 301, 313, 314, PI. 26. 



Orion, 395. 



Orreries, 433. 



Orthographical projection, 89, PL 8. 



Oscillations of fluids, 217. 



Osiris, 315. 



Overflowing lamp, PI. 21. 



Overshot wheel, 244, PI. 22. 



Ovid, 181. 



Oxid, 495. 



Oxygen, 340. 



Oxygen gas, 486. 



Painting, 356. 



Palladio, PI. 11 ; b. 1508, d. 1580. 



Pallas, 404, 424. 



Panorama, 356. 



Pantheon, 127,526, PI. 12. 



Pantograph, 79, PI. 6. 



Paper, 75, 144, 186. 



Papin, 264, 290- 



Pappus, J85, 186; fl. 383. 



Papyrus, 75. 



Parabola, 31, 293, PI. 2. 



Parabolas, PI. 10. 



Parabolic jet, 217. 



Parabolic orbit, 414. 



Parachutes, 233. 



Paradox. Hydrostatic paradox, 199. 



Parallax, 430. 



Parallax of the sun, 431, 432. 



Parallel motion, PI. 14. 



Parallelogram, 18. 



Parallel rulers, 78, PI. 14. 



Pardies, J79, 380 ; b. 1636, d. 1673. 



Parent, 191, 248 ; b. 1666, d. 1716. 



Parent's mill, 248, 253. 



Parhelia, 347, PI- 29. 



Paris, 356. 



Parisian academy, 191, 192, 279, 280. 



Parker, 131. 



Partial electricity, 509. 



Partial reflection, 362. 



Pascal, 504 ; b. 1623, d. 1662. 



Passive strength, 71, 104, PI. 11. 



Paternoster work, 256. 



Path of the centre of gravity, PI. 3. 



Path of the sun, 417. 



Paths of the planets, PI. 34. 



Pear gage, 262, PI. 24. 



Pearson, 433. 



Pedestrian, 100. 



Pegasus ,395, 588. 



Pemberton, 191,459. 



Pen, 72. 



Pencil, 72, 73. 



Pencil of light, 320, PL 26. 



Pendulum, 34, 35, 83, 147, PL 2, 5, Circular 



pendulum, 36. 

 Pendulums, 417, 443. 

 Penetration, 111, 120, 172. 

 Pennant, 586 ; b. 1726, d. 1798. 

 Pens, 75. 



Pens for lines, 77. 

 Penumbra, 419. 



Perception of external objects, 351. 

 Percussion, 171. 

 Perforation of ajar, 517. 

 Periodical winds, 548. 

 Periods of the planets, 402, PL 32. 

 Periscopic spectacles, 332. 

 Permeability of matter, 468. 

 Perpetual motion, 70, PL 6. 

 Perrault, 157, 191 ; b. 1613, d. 1688. 

 Perrault's ropes, 164. 

 Perseus, 394. 

 Persians, 428, 456. 

 Perspective, 71, 88, PL 7, 8. 

 Perturbations, 412. 

 Petit, 488. 

 Pfaff, 588. 



Phantasmagoria, 333, PI. 28. 

 Phases of planets, 418. 

 Phases of the moon, 419. 

 Phenicians, 74. 



Pherecydes, 181; b. 600, d. 515, B.C. 

 Philip III., 460. 

 Philo, 183, 185, 276. 

 Philolaus, 453. 

 Philosophizing, 12. 

 Phosphorus, 486. 

 Phosphorus of Bologna, 341. 

 Photometers, 329, PI. 27. 

 Physical astronomy, 387. 

 Physical optics, 340. 

 Physics, 387. 

 Physiology, 5?a 

 Pianoforte, 311. 

 Piazzi, 404, 462. 

 Picard, 34, 435, 460 ; d. 1682. 

 Pictet, 289, 486, 487> 489, 552, 587- 

 Piers, 126, 240. 

 Pile engine, 137, 173, PL 1* 

 Pile of Volta, 522, 588. 

 Pin, 119. 



Pinion, 136, PL 15. 

 Pipe. Effect of a short pipe, 212, 213. Vertical 



pipe, 215. 



Pipes, 222, 277- Musical pipes, 296. 

 Pipes of lead, 242. 

 Pipes of pumps, 256. 

 Pisces, 401. 

 Pise, 123. 

 Piston, PL 28. 

 Pistons, 254. 

 Pitot, 243. 



Pittacus, 181 ; b. 652, d. 570, B.C. 

 Pixii, 541. 



Plain astronomy, 387. 

 Plane mirror, 325. 

 Planetarium, 433. 

 Planetary worlds, 422. 

 Planets, 400, PL 32. 

 Planispheres, 433. 

 Planks, PL 10. 

 Planoconcave lens, 326. 

 Planoconvex lens, 326. 

 Plant, 568. 

 Plaster of Paris, 87- 

 Plate machine, 525, PL 40. 





