1802 Herschel's discovery of binary stars.

1802 Marks of cl.u.s.tering in the Milky Way noted by Herschel.

1802 Wollaston records seven dark lines in the solar spectrum.

1802, Nov. 9 Transit of Mercury observed by Herschel.

1804, Sept. 2 Discovery of Juno by Harding.

1804 Foundation of Optical Inst.i.tute at Munich.

1805 Herschel's second determination of the solar apex.

1807, March 29 Discovery of Vesta by Olbers.

1811 Herschel's theory of the development of stars from nebulae.

1811, Feb. 9 Death of Maskelyne. Pond appointed to succeed him as Astronomer-Royal.

1811, Sept. 12 Perihelion pa.s.sage of great comet.

1812 Theory of electrical repulsion in comets originated by Olbers.

1812, Sept. 15 Perihelion pa.s.sage of Pons's comet.

1814 Herschel demonstrates the irregular distribution of stars in s.p.a.ce.

1815 Fraunhofer maps 324 dark lines in the solar spectrum.

1818 Publication of Bessel's _Fundamenta Astronomiae_.

1819 Recognition by Encke of the first short-period comet.

1819, June 26 Pa.s.sage of the earth through the tail of a comet.

1820 Foundation of the Royal Astronomical Society.

1821 Foundation of Paramatta Observatory.

1821, September First number of _Astronomische Nachrichten_.

1822, May 24 First calculated return of Encke's comet.

1822, August 25 Death of Herschel.

1823 Bessel introduces the correction of observations for personal equation.

1823 Fraunhofer examines the spectra of fixed stars.

1824 Distance of the sun concluded by Encke to be 95-1/4 million miles.

1824 Publication of Lohrmann's Lunar Chart.

1824 Dorpat refractor mounted equatoreally.

1826 Commencement of Schwabe's observations of sun-spots.

1826, Feb. 27 Biela's discovery of a comet.

1827 Orbit of a binary star calculated by Savary.

1829 Completion of the Royal Observatory at the Cape of Good Hope.

1829 The Konigsberg heliometer mounted.

1830 Publication of Bessel's _Tabulae Regiomontanae_.

1832 Discovery by Brewster of "atmospheric lines" in the solar spectrum.

1833 Magnetic observatory established at Gottingen.

1833, Nov. 12,13 Star-shower visible in North America.

1833 Completion of Sir J. Herschel's survey of the northern heavens.

1834, Jan. 16 Sir J. Herschel's landing at the Cape.

1835, September Airy appointed Astronomer-Royal in succession to Pond.

1835, Nov. 16 Perihelion pa.s.sage of Halley's comet.

1837 Solar movement determined by Argelander.

1837 Bessel's application of the heliometer to measurements of stellar parallax.

1837 Publication of Beer and Madler's _Der Mond_.

1837 Publication of Struve's _Mensurae Micrometricae_.

1837, Dec. 16 Outburst of Eta Carinae observed by Sir J. Herschel.

1837 Thermal power of the sun measured by Herschel and Pouillet.

1838 Parallax of 61 Cygni determined by Bessel.

1839, Jan. 9 Parallax of Alpha Centauri announced by Henderson.

1839 Completion of Pulkowa Observatory.

1839 Solidity of the earth concluded by Hopkins.

1840, March 2 Death of Olbers.

1840 First attempt to photograph the moon by J. W. Draper.

1842 Doppler enounces principle of colour-change by motion.

1842 Conclusion of Baily's experiments in weighing the Earth.

1842, July 8 Total solar eclipse. Corona and prominences observed by Airy, Baily, Arago, and Struve.

1843, Feb. 27 Perihelion-pa.s.sage of great comet.

1845, February Completion of Parsonstown reflector.

1845, April Discovery with it of spiral nebulae.

1845, April 2 Daguerreotype of the sun taken by Foucault and Fizeau.

1845, Oct. 21 Place of Neptune a.s.signed by Adams.

1845, Dec. 8 Discovery of Astraea by Hencke.

1845, Dec. 29 Duplication of Biela's comet observed at Yale College.

1846 Melloni's detection of heating effects from moonlight.

1846, March 17 Death of Bessel.

1846, Sept. 23 Discovery of Neptune by Galle.

1846, Oct. 10 Neptune's satellite discovered by La.s.sell.

1847 Publication of Sir J. Herschel's _Results of Observations at the Cape of Good Hope_.

1847 Cyclonic theory of sun-spots stated by him.

1848 J. R. Mayer's meteoric hypothesis of solar conservation.

1848 Motion-displacements of Fraunhofer lines adverted to by Fizeau.

1848, April 27 New Star in Ophiuchus observed by Hind.

1848, Sept. 19 Simultaneous discovery of Hyperion by Bond and La.s.sell.

1849 First experimental determination of the velocity of light (Fizeau).

1850, July 17 Vega photographed at Harvard College.

1850, Nov. 15 Discovery by Bond of Saturn's dusky ring.

1851 O. Struve's first measurements of Saturn's ring-system 1851, July 28 Total solar eclipse observed in Sweden.

1851, Oct. 24 Discovery by La.s.sell of two inner Uranian satellites.

1851 Schwabe's discovery of sun-spot periodicity published by Humboldt.

1852, May 6 Coincidence of magnetic and sun-spot periods announced by Sabine.

1852, Oct. 11 Variable nebula in Taurus discovered by Hind.

1852 La.s.sell's two-foot reflector transported to Malta.

1853 Adams shows Laplace's explanation of the moon's acceleration to be incomplete.

1854 Hansen infers from lunar theory a reduced value for the distance of the sun.

1854 Helmholtz's "gravitation theory" of solar energy.

1856 Piazzi Smyth's observations on the Peak of Teneriffe.

1857 Saturn's rings shown by Clerk Maxwell to be of meteoric formation.

1857, April 27 Double-star photography initiated at Harvard College.

1858 Solar photography begun at Kew.

1858, Sept. 30 Perihelion of Donati's comet.

1859 Spectrum a.n.a.lysis established by Kirchhoff and Bunsen.

1859 Carrington's discovery of the compound nature of the sun's rotation.

1859, Sept. 1 Luminous solar outburst and magnetic storm.

1859, Oct. 19 Merope nebula discovered by Tempel.

1859, Dec. 15 Chemical const.i.tution of the sun described by Kirchhoff.

1860, Feb. 27 Discovery by Liais of a "double comet."

1860, May 21 New star in Scorpio detected by Auwers.

1860, July 18 Total solar eclipse observed in Spain. Prominences shown by photography to be solar appendages.

1861, June 30 The earth involved in the tail of a great comet.

1861-1862 Kirchhoff's map of the solar spectrum.