1860-70] 
ROYAL ASTRONOMICAL SOCIETY 
161 
recognise in 1799 that the meteors radiated from a point fixed in 
relation to the stars. It was Olmsted, of Yale University, who 
first in 1834 recognised the significance of this point as indicating 
the direction of the meteors in their approach to the earth, and 
he regarded them as a form of comet describing an elliptical 
orbit with a period of about 182 days, and meeting the earth near 
aphelion. Erman, of Berlin, discussing in 1839 the similar 
problem presented by the August meteors (Perseids), found it 
necessary to assume that the meteors in that case formed a con 
tinuous stream along their orbit. 
Olbers, in 1839, was to predict a fine display of Leonids in 
1867 November. But fortunately H. A. Newton, Professor in 
Yale University, published in 1864 hi s well-known discussion of 
ancient records of November meteors, dealing with thirteen 
showers since a.d. 902, and indicating the existence of a cycle of 
33-25 years. Considering the phenomena to be caused by a ring 
of meteoroids revolving round the sun, he showed that in one year 
the meteoroids must describe either 2±-^- or id-—, or 
revolutions. He further pointed out that the longitude of the 
node of the orbit is gradually increasing, and that its observed 
motion would afford a method for deciding which of the five 
periods is the correct one, if only the perturbations by the various 
planets were calculated. He predicted a fine display of meteors 
for 1866 November, a year earlier than Olbers’s date. When 
Newton’s prediction was verified, the problem became a very 
attractive one. It was made all the more attractive by Schia 
parelli’s discovery that the cosmical orbit of the Perseid meteors 
coincided closely with the orbit of the retrograde comet which was 
discovered by Swift in 1862, and which reached perihelion on 
August 22 of that year. 
The spring of 1867 is made memorable by a display of striking 
Memoirs following one another with almost meteoric rapidity. 
In January Le Verrier published his Memoir showing that a swarm 
of meteors with a period of 33-25 years would intersect the orbit 
of Uranus, but from its inclined position indicated by the radiant’s 
latitude io° it would not intersect the paths of Saturn, Jupiter, or 
Mars. His calculations showed that in a.d. 126 there would have 
been a close approach of Uranus to such a swarm, and that that 
date might be the epoch of the capture of the swarm for the solar 
system by their diversion into a retrograde elliptic orbit of period 
33-25 years. 
In 1867 February, C. F. W. Peters and Oppolzer pointed out 
the close resemblance of Oppolzer’s orbit for the comet discovered 
by Tempel in 1865 December, which reached perihelion on 1866 
January 11, to Le Verrier’s orbit of the meteors.