4.72 Cambridge Philosophical Society :— 
when he first saw it, and that the time and place of entrance were 
inferred by estimation. 
The following are the immediate results of the observations :— 
The spot entered at 45 5™ 36° mean time of Orgéres at the angular 
distance of 57° 22' from the north point towards the west, and de- 
parted at 55 22™ 44s, at 85° 45! from the south point towards the 
west, occupying consequently in its transit 1" 17™ 88. The length 
of the chord it described was 9! 14", and its least distance from the 
sun’s centre 15! 22, M. Lescarbault also states that he judged the 
apparent diameter of the spot to be at most one-fourth of that of 
Mercury, when seen by him with the same telescope and magnifying 
power during its transit across the sun on May 8, 1845. ‘The lati- 
tude of Orgéres is 48° 8' 55", and longitude west of Paris, 2™ 355. 
From these data M. Leverrier ascertained, by calculating on the 
hypothesis of a circular orbit, that the longitude of the ascending 
node is 12° 59!, the inclination 12° 10’, the mean distance 0°1427, 
that of the earth being unity, and the periodic time 19°7 days. Also 
he found that the greatest elongation of the body from the sun is 8°, 
the inclination of its orbit to that of Mercury 7°, the real ratio of 
its diameter to Mercury’s 1 to 2°58, and that its volume is one- 
seventeenth the volume of Mercury on the supposition of equal den- 
sities. This mass is much too small to account for the perturbation 
of Mercury’s perihelion. According to these results, the periods at 
which transits may be expected are eight days before and after 
April 2 and October 5, the body being between the earth and sun 
near its descending node at the former period, and near its ascend- 
ing node at the latter. 
After the announcement of this singular discovery, it was found 
that other observations of a like kind had been previously made. 
Several instances are collected by Professor Wolf in the tenth num- 
ber of his Mittheilungen tiber die Sonnenflecken, eight of which are 
quoted in vol. xx. (p. 100) of the Monthly Netices of the Royal 
Astronomical Society. ‘I‘wo of these, the observation of Stark on 
October 9, 1819, and that of Jenitsch on October 10, 1802, agree 
sufficiently well with the calculated position of the node of the object 
seen by Lescarbault. But the spot seen by Stark is stated to have 
been about the size of Mercury. 
Capel Lofft saw at Ipswich, on January 6, 1818, at 11 a.m.,a 
spot of a ‘sub-elliptic form,’ which advanced rapidly on the sun’s 
disc, and was not visible in the evening of the same day (Monthly 
Magazine, 1818, part 1, p. 102). 
Mr. Benjamin Scott, Chamberlain of London, saw about mid- 
summer of 1847 a large and well-defined round spot, comparable in 
apparent size with Venus, which had departed at sunrise of the next 
day (Evening Mail, January 11, 1860). 
Pastorff of Buchholz records that he saw on October 28 and 
November 1, 1836, and on February 17, 1837, two round black, 
spots of unequal size, moving across the sun at the respective hourly 
rates of 14’, 7", and 28’. Also he announced, January 9, 1835, to 
the Editor of the Astronomische Nachrichten, that ‘‘ six times in the 
