CONTENTS.

XIX

Aristotle ; Archimedes ; Euclid ; Ptolemy ; Alhazen >Vitellio ; It. Baron ; 473. Jansen ; Galileo ; Kepler ;Schemer ; Rheitu ; Maurolycus; lie Dom'mis; Sncl.lius; Descartes ; 474. Fermat ; Leibnitz ; Barrow ;Boyle; Iloolce; 475. Newton ; Grimaldi; 476-Bartholin; Huygens ; Roomer, Bradley ; 477. Bou-

PAKT T11E TI1I1U).Lecture xli. On the fixed stars;487.

Division of the subjects of physics ;487. Astronomy ;488. Empty S| ace ; fixed stars ; 489. Eight of thestars; Figure; Twinkling; Number; Magnitudes;490. Distances of the stars ; 491. Clusters or ne-bulae ; 492. Arrangement of the stars in general ;M itky way ; Proper motions of the stars ; 493. Dr.

II erschel's division of stars and nebulae ; Changes ofthe stars; 494. Constellations; 495. Representa-tions of the stars ; Allincations ; 49(3 . . 498.

Lecture xlu. On the solar system ;499.

T he sun a star; Progressive motion of the sun;499. Orbit of the sun; Rotation; 500. Spots;Solar heat; 501. Sim’s attraction ; Solar atmosphere;502. Planets; Ecliptics ; 503. Change of positionof the ecliptic ; Nodes; Kcplerian laws ; 504. Rota-tion of the planets ; Precession of the equinoxes; 505.Nutation of the earth’s axis ; Proportional distancesof the planets ; Mercury ; 506. Venus ; The earth ;Maft; 507. Juno; Pallas; Ceres ; Jupiter ; Saturn ;

508. Georgian planet ; Unknown planets; Satellites;

509. Moon ; 510. Satellites of Jupiter ; Ring ofSaturn; 511. Comets; 512. Number and orbits ofthe comets; 513.

Lecture xlui. On the laws of ora-

V °

vitation;

Newton ’s great discovery ; Attraction of sphericalbodies; 515. Extent of the force ofgravity ; 510.Suit’s change of place ; Orbits of the planets ; Kep-leriuu laws ; 517. Universality of gravitation ; Mo-tions of the apsides and nodes; Changes of theecliptic; Forms of the planets; 518. Precession;Nutation; Lunar motions ; 519. Disturbing force ofthe sun ; 520. Acceleration of the moon’s motion ;

guer ; Porterfield; Jnrin ; Smith; Dollond ; llall ;478. Euler ; 479. Lambert; Mathematical opti-cians; Maztlas; Dutour ; Comparetti ; Priestley;480. Delaual ; It. Darwin ; Atmospherical refrac-tion ; Wollaston; Ritter; Uerschel ; 481. Laplace ;Attempts of the author; 482. Chronological table; 488’

ph. vsics ; 485.

Moon ’s rotation ; Orbits of comets; 521. Predictionsof Halley and Clairaut ; 522. Chronological table; 483.

Lecture xeiv. On the appear-ances of the celestial bodies ; 523.

Apparent motions to be described alter the realones ; Motions of the stars and sun ; Motions of theearth; 523. Apparent revolution of the sun ; 524.Sun ’s apparent diameter; Length of summer and win-ter; Day and night ; Sun ’s apparent path ; 525. Cen-trifugal force ; Places of the stars ; Twilight, 526.Relative positions and phases of the planets; 527.Phases of the moon : Lunar eclipses ; 528. Eclipsesof the sun ; Scries of eclipses ; 529. Harvest moon ;Eclipses of Jupiter ’s satellites; 530. Comets; Lightof the heavenly bodies ; Planetary worlds; 531. Fon-tcncllc ; Mercury ; Venus ; 532. Moon ; 533. Mars ;Newly discovered planets; Jupiter ; 531. Saturn ;Georgian planet; 535.

Lecture xlv. On practical astro-nomy ; 536 .

Ileal motions neglected ; Sit uation of a point in theheavens ; Meridian ; 536. Astronomical instruments:Time ; Sidereal day ; Solar day; Equation of time >537. Dialling; Chronology; 538. Calendar; 539.Improvement suggested ; Republican calendar; Me-tonic cycle; Golden number; 540. Epact; Moon ’sage; Julian period ; Astronomical time; Quadrants;Transit instruments ; 541. Hadley’s quadrant; De-clinations ; Refraction aud parallax ; 642. Latitudes:Longitudes; 543. Lunar observations; Distance ofthe sun; Transits ; 544. Densities of the sun andplanets; Artificial globe ; “ 565”. Planispheres ;2566-Orreries; 567.

Lecture xlvi. On Geography ; 568.

Particular account of the earth; Curvature of itssurface; Direction of the plumb line; 568. Ellipti-