of Edinburgh, Session 1879-80. 429 
a degree of /3 Leonis. The path would cut the ecliptic with geo- 
centric longitude = 170°. 
This will be conclusive evidence to all that these four comets are 
identical, and this in itself is an interesting deduction from the 
present research. 
The eccentricity and longitude of perihelion of the plane of the 
planet’s orbit can be estimated by noticing the different aphelion 
distances at different longitudes. This gives us '08 as the eccen- 
tricity and zt about 290.° 
The period of the supposed planet gives a mean distance = 98, 
which agrees with what goes before. 
The elements of the planet for July 1880 are consequently — 
«= 98° 
n = 250° 
i= 53° 
6 = -08° 
•sr = 290° 
Motion direct. 
Distance of planet from node = 296°. 
Its present longitude measured from O up to the node and then 
along the planet’s orbit is 185°. 
[ Additional Note , 31s£ March 1880. — Another calculation was 
made on the supposition of the planet being on the plane of the 
ecliptic, and Affecting the comets when nearest to their aphelion 
positions. This gives its present longitude = 184°. 
This hypothesis is strongly supported by the fact that the author 
has computed the position of Neptune by its influence on comets 
correct within 2°, although previously ignorant of its position.] 
From the six comets whose aphelion distance is about 300 times 
the distance of the earth from the sun, the elements of the perturbing 
planet have roughly been calculated. This gives — 
n=i85° 
i= 45° 
nearly the same orbit as the preceding. The present position is — 
R. A. 22h. 0m. 
N. Declination 39°. 
In the neighbourhood of this position, but at a position occupied by 
