194 The N.Z. Journal of Science and Technology. [Aug. 
The ephemeris 
other dates, is :— 
of the comet, calculated in a similar manner for the 
1921 
Ephemeris. 
r = Distance a = Distance 
G.M.T. 
R.A. 
Dec. 
from Sun 
(Millions of 
from Ear 
(Millions 
June 12-95 
h. m. s. 
22 29 28 
15° 
32' N. 
Miles). 
96-6 
Miles). 
13-0 
22-455 
23 44 3 
6° 
14' S. 
97-4 
14-8 
July 2*112 
0 33 56 
20° 
40' S. 
99-7 
19-3 
12-070 
1 5 11 
29° 
31' S. 
103-5 
24-8 
A check of the elements and of this ephemeris has been obtained from 
the observed positions of the comet, which agree closely with the predicted 
Fig. 2. 
Owing to the increasing distance of the comet, both from the Sun and 
from the Earth, it is rapidly becoming fainter and is now a telescopic 
object and not visible to the naked eye. 
The illustration (fig. 1) shows the Earth and Sun in the plane of the 
ecliptic, and the positions of the comet projected on to the ecliptic. It 
will be noticed that the comet’s orbit is outside the Earth’s orbit. The 
corresponding positions of the comet and the Earth are joined by a line. 
Fig. 2 is taken from Proctor’s Southern Skies ,* and on it are shown 
the four positions of the comet. The figure shows the night sky at 
the following times : September 6, at 1 a.m.; October 7, at 11 p.m.; 
November 7, at 9 p.m. 
1921, July 15. 
* R. A. Proctor, The Southern Sides , Longmans, Green, and Co., London, 1896. 
