WHAT WE KNOW ABOUT COMETS 543
was essentially identical with the orbit of Comet 1862III. Here are the elements of the two orbits.
Meteora of August Orbits of 9. 10. 11 Comet 1M2III
Perihelion passage July 23.62 August 22.9
Longitude of perihelion 343° 38' 344** 41'
Ascending node 138 16 137 27
Inclination 63 3 66 25
Perihelion distance 0.9643 0.9626
Period of revolution 105 years? 123.4
Direction of motion retrograde retrograde
The difference in the two perihelion times does not mean that their orbits were different even to the minutest degree, but only that, moving on the same orbit, they reached the point nearest the sun at slightly different times ; that is, one of the bodies traveled over the orbit a little in advance of the other. The revolution period assigned to the meteors is subject to considerable error because it is not possible to observe the paths of the meteors with great accuracy.
There were rich and startling showers of meteors on November 12, 1799, and on November 12-13, 1833. H. A. Newton examined the literature of meteoric falls and found that many similar showers had been observed at intervals of thirty-three years running back several centuries, to 902 a.d., *'the year of the stars,'^ and he confidently predicted that another great shower would occur on November 13-14, 1866. His prediction was abundantly verified. Early in 1867 Schia- parelli and Le Verrier independently computed the orbit of these meteors, and Schiaparelli and Oppolzer independently found it iden- tical with the orbit of the comet 18661. Here are the elements of the two orbits :
Meteors of Novem- Orbits of ber 18 Comet 18661
Perihelion passage November 10.092 January 11.160
Longitude of perihelion 56^ 25'.9 60** 28'.0
Ascending node 231 28 .2 231 26 .1
Inclination 17 44 .5 17 18 .1
Perihelion distance 0.9873 0.9765
Eccentricity 0.9046 0.9054
Semi-major axis 10.340 10.324
Period of revolution 33.250 years 33.176 years
Direction of motion retrograde retrograde
It is impossible to doubt that these November meteors and the comet referred to were traveling in the same orbit.
The so-called Lyra meteors are visible about April 20 each year. It was noticed in 1867 by Weiss that the orbit of the Lyra meteors is essentially identical with that of the comet 18611.
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