of Edinburgh, Session 1879-80. 
637 
probable position of an ultra-Neptunian planet, I have now to 
inform the Society that I have detected the existence of perturba- 
tions in the motion of Uranus, agreeing remarkably in character 
and period with those which would be produced by the new planet. 
These results are obtained from observations of Uranus extending 
over more than a century. The position of the planet, from this 
point of view, is found, from the first rough examination, to be 
the same as that given by me in my former memoir. This gives 
a means of determining the mass of the new planet. In this 
way I find it to be about the same as that of Saturn. I have 
also some reasons for believing that the following stars observed 
by Riimker, but stated by E. J. Cooper (“ Markree Catalogue of 
Stars,” vol. iv. p„ 229) to be missing, are actually the new planet. 
Number. 
3320 
In Each, 
3372 
R.A. 
lOh. 37m. 24s. 203 
10 38 47 179 
10 44 24 365 
N. Decl. 
10° 50' 57" 21 
10 46 
9 55 52 58 
I have not Riimker’s Catalogue at hand at this moment to 
identify them. 
The following star in Bessel’s zones is also missing, and may be 
an observation of the planet. Cooper declares it to be missing. 
Mag. Zone. R.A. N. Decl. 
9 280 9h. 51m. 59s. 82 16° 45' 12" 5 
Monday , *lth June 1880. 
J. H. BALFOUR, M.D., in the Chair. 
The Chairman presented the Keith Medal for the Biennial 
period 1877-79, to Professor Fleeming Jenkin, for his Paper 
“ On the Application of Graphic Methods to the Determina- 
tion of the Efficiency of Machinery,” the second part of which 
was published in the Society’s Transactions for 1878, and in 
doing so made the following remarks : — 
Professor Jenkin has contributed several valuable papers to our 
Transactions. 
