TOTAL SOLAR ECLIPSE OF JULY 18, 1860. 
345 
cess of my photographic operations, and also with the arrangements of the observatory, 
and the many preparations which had been made to secure the result. 
At 2*’ 30“, a comparison was made between Mr. Airy’s pocket chronometer Moly- 
neux No. 1007 and the box chronometer Frodsham No. 3094 ; Molyneux was slow of 
Frodsham 3094 43 seconds. 
Molyneux 1007 was slow of Greenwich mean time, 
losing daily 7 ‘2 seconds, 
gaining daily 2 ’7 seconds. 
h 
sec. 
On July 16 . 
. 23 
28-8 
July 17 . 
. 22 
35-7 
July 18 . 
. 22 
33-0 
Applying the latter rate, Molyneux would appear to have been, on July 19, 2^ 30™, 
32’5 seconds slow, and consequently Frodsham 3094 10-5 seconds fast of Greenwich 
mean time. I believe that Molyneux 1007 could not be greatly depended on ; but, the 
comparison of chronometers having been made, I place the result on record, although I 
am not able to make it accord with the other observations within several seconds. 
Observations. 
The following observations were made with the transit theodolite. During the day 
the instrument had to remain exposed to the sun ; and this caused the several parts to 
expand very unequally, and kept the bubble in the level always in motion — a circum- 
stance which proved very troublesome. 
Estimation of Longitude. 
July 12. Four pairs of reduced observations of equal altitudes of the sun showed that 
at local mean noon 
Frodsham 3094 was fast of local mean time ... 11 min. 51 ‘9 sec. 
July 14. Two pairs of reduced observations of equal alti- 
tudes of the sun showed that at local mean noon 
Frodsham 3094 was fast of local mean time ... 11 min. 51‘3 sec. 
With reduced observations of the azimuths of equal altitudes of the sun on the 12th and 
the 14th, northern and southern adjustable meridian marks were placed, the first against 
a building, the second against some trees ; both sufficiently distant to give distinct vision 
of the mark, which was a cross X of wood, moveable in a top and a bottom groove in 
a wooden frame. 
Attempts were made on the night of the 13 th to obtain observations of stars; but the 
weather was too cloudy ; by dint of perseverance, however, 1 did manage to get, through 
breaks in the clouds, the meridian altitude of a Lyrse, and an altitude of the pole star 
out of the meridian, presently to be referred to in the determinations of latitude. 
On the night of the 14th I was more fortunate, and was able to obtain observations 
of a high and low star, and finally to adjust the meridian marks by means of an obser- 
vation of b Ursae Minoris on the meridian. As soon as the observation of b Ursse Minoris 
