632

INDEX.

adopts the hypothesis of a central sun,558 ; views respecting the structure of theMilky Way , 574.

Lamont—Researches on the satellites ofUranus , 285.

Laplace—his opinion respecting the Prin-cipia, 33; his researches on the meannotions of the planets, 51; investigatesthe secular variations of the planetaryelements, 52; his theorems relative to thestability of the planetary system, 55; ex-plains by the theory of gravitation thelong inequality of Jupiter and Saturn , 59 ;discovers the physical origin of the secularinequality in the moon’s mean motion andcomputes its amount, 62; investigatesthe secular inequalities of the perigee andnodes of the lunar orbit, 64 ; computes thelunar inequalities depending on the sphe-roidal figure of the earth, 65; investi-gates the inequality in the moon’s longi-tude depending on the solar parallax, ib.;discovers inequalities in the moon’s mo-tion, depending on the spheroidal figureof the earth, ib.; determines the lunarinequality in longitude involving the solarparallax, ib.; theory of the attraction ofspheroids, 69 ; demonstrates the stabilityof the ocean, 71; researches on the tides,ib. ; investigates the disturbing influenceof the ocean on the earth’s axis, ib. ; re-searches on the stability of Saturn ’s rings,76; investigates the perturbations of Ju­ piter ’s satellites, 91; researches on thediminution of the obliquity of the ecliptic,99; comparison of his formula with anancient Chinese observation, ib. ; investi-gates the secular variation of the tropicalyear, ib.; discovery of an invariable planein the solar system, 101; publication ofthe Mecanique Celeste , 108; researcheson the variations of the elements of theplanetary orbits, 111; suggestion respect-ing the cause of the irregularities inthe moon’s epoch, 119; determines themass of the moon, 122; researcheson the mean temperature of the earth,162; oscillations of the atmosphere, ib.;first calculates the elliptical elements ofUranus , 275; hypothesis relative to theheat of comets, 314; researches on thetheory of refraction, 331.

Lassell—discovers the eighth satellite of Sa­ turn , 271; reobserves one of the satellitesof Uranus , 286; discovers a satellite re-volving around Neptune , ib.; effects im-provements in the construction of reflect-ing telescopes, 536; discovers two satel-lites of Uranus , Appendix .

Le Yerrier—his researches on the inclina-tions of the planetary orbits, 116; in-vestigates the secular variations of theplanetary elements, 117 ; investigates thetheory of Mercury, 125; calculates thelong inequality of Pallas, 132; researches

on the perturbations of Faye’scomct, 139 ;researches on the identity of the cometsof Lexell aud Faye, 140; proves them tobe distinct bodies, 141; researches on theidentity of the comets of 1585 and 1843,ib.; investigates the theory of Uranus ,175; fails to account for the observed ir-regularities of theplanet, 177; investigatesthem upon the hypothesis of a disturbingplanet, 178; first results which he ob-tained, 183; second investigation of thesubject, 187; final results deduced byhim, 188; remarks on the physical aspectof the disturbing planet, 190.

Lexell—shews that the comet which bears hisname revolved in an elliptic orbit, 105;his explanation of its disappearance, ib.;first suspects Uranus to be a planet, 274;determines its apparent diameter, 275.

Light—Researches of Struve on the ex-tinction of, in its passage through space,

577.

Lipperhey —proved to be the original in-ventor of the telescope, 519.

Longitude—Arc of, measured in the British Isles , 150.

Louville—applies the micrometer to dividedinstruments, 481.

Lubbock—Researches on the lunar theory,

120 .

Lunar Mountains—first discovered by Gali­ leo , 229 ; various determinations of theiraltitudes, ib.

Maclaurin —his researches on the equili-brium of ellipsoids, 67; investigates thesubject of the tides, 71.

Maclear—observes Halley’s comet after thepassage of the perihelion in 1835, 138;geodesical operations at the Cape of Good Hope , 148; researches on the parallax ofa. Centauri, ib.

Madler—Surmise respecting the possibilityof discovering a planet beyond Uranus ,167; executes, in conjunction with Beer ,a chart of the moon’s surface, 230; de-termines the ellipticity of Uranus , 278;speculations on the existence of a centralsun, 558.

Main—demonstrates the elliptical figure ofSaturn , 266 ; researches on the propermotions of the stars, 557.

Mairan—Hypothesis of Saturn ’s ring, 267.

Maraldi I.—his researches on Jupiter ’s satel-lites, 80; rejects the equation of light,81; discovers that the inclination of thesecond satellite is variable, ib. ; deter-mines the time of rotation of Mars , 236 ;physical observations of the satellites ofJupiter , 248; observations of Saturn ’sring, 263.

Maraldi II.—Researches on the motions ofJupiter ’s satellites, 83; discovers that theinclination of the third satellite is variable,ib.; establishes the eccentricity of the