232 J. C. Watson—Intra- Mercurial Planet. 
also been placed along this ledge as a more complete protection 
in case of very strong winds. 
Upon reading the circles and reducing the observations, it 
is rendered probable that the telescope was disturbed in this 
instance; but I give the observations as they were made com- 
plete, in order that they may be made available in any future 
discussion. The places of the sun were again recorded and 
verified, and thus the position of the star a (which I believe to 
be an intra-Mercurial planet) can be determined relatively to 
the sun. The linear distances on the paper discs were roughly 
measured immediately after the observations, and the result 
was to show that the object which I had designated by a on the 
circles is not a known star. Since my return to Ann Arbor, 
I have placed the paper dises on the axis of a graduated circle, 
and setting them by means of a pointer, I have read off the 
positions. They are shown by the following table, in which 
the readings given are the mean of five readings on each mark: 
Chronometer Time. Object observed. Circle readings. 
4° 39™ 50° Sun 168° 16'°3 
4 48 56 Planet (a) 163 50°9 
4 50 5 6 Cancri (4) 158 49° 
4 55 10 Sun 164 246 
5 4 50 Sun 161 52°3 
The three comparisons of (a) with the sun give 
Planet — ©. 
Aa. 
(2) —8 288 
; (3) ~7 598 
The mean is 
4a=—8 21°, 
The difference in declination measured on the circle is 
46 = —0° 22’ 
The place of the sun for the instant of observation is 
’ a = 8" 35™ 56°. 6 = +18° 38'°4. 
and hence we derive 
: t 
Washington Mean Time. me : bibs 
1878, July 29, 5" 16™ 378, gt oym 358. +18° 16’. 
It was not possible in the brief period of totality to change 
the eye-piece in order to observe the object under a high power: 
I can only state in addition to the above, that the appearance 
of the object arrested my attention even before I moved the 
telescope to the known star farther to the eastward. It was 
Meat Ses tres ieee eo ae A 
