ON THE ORBIT-ELEMENTS OF COMET I., 1880, 35 
comparison only with o Sculptoris. This circumstance, it will 
be seen, is an unfortunate one. The three adopted apparent 
positions of the comet are as follows :— 
Melbourne Mean Time. R. A. a. PD, 
a, ha, e, 
ren, 2: 9... Fae 
9 14.9 59: 26:7 
ioc wk: 8 we oe 
123° 43’ 43” 
2 5°62 122 21 8 
41 951 120 21 43 
mm 0 
He 
ee 
for) 
3 
Correcting these times and positions for aberration and parallax 
and adopting the ecliptic as the fundamental plane, we get the 
following co-ordinates referred to the mean equinox of the be- 
ginning of the year :— 
Feb. Righchrs Greenwich M. T. A=341° 5'34°1” B= -28° 49’ 39°5” 
boon iy A’=359 36 56 p’=-35 31 01 
- - ane = "= 9 57 70 p’=-37 37181 
The places of the sun have been taken from the British Nautical 
Almanac, have been duly corrected for aberration and reduced to 
the same equinox. The logarithms of the earth’s radius vector 
have been taken from the same source. Assuming now the 
proportionality of the rectilinear instead of the parabolic sectors 
described by the comet to the times of description, I arrived at a 
value of the ratio of the curtate distances of the comet from the 
earth for the first and third observations, which, when Lambert’s 
theorem was satisfied, gave a system of elements differing but 
little from that communicated by Mr. Hin n correcting the 
assumption from which the ratio was derived I obtained another 
system differing considerably from the other. By a comparison 
of the residuals in longitude and latitude for 2 middle observa- 
tion, as derived from these two sys Id 
value of the ratio, which gave finally the kliowig system of 
parabolic elements :— 
Perihelion passage .....,.......++0+5 1880, January 27°56330d G.M.T. 
Longitude of the perihelion ...... 277° 22’ 53”°4 : 
Longitude of the ascending node 358 22 48 °6 M.Equinox, 1880°0 
Inclination of the orbit............ 36 41 41 ‘9 
Perihelion distance 0°0067243 
Heliocentric motion ............... Retrograde 
On recalculating the geocentric places from these elements, I 
obtained the following residuals, in the sense of calculation minus 
observation :— 
Feb. 8 Ad cosB =—- 5" 2 AB=+ 05 
freee AX’ cos 8’ = + 59 °7 Af’ =- 77 6 
” 16, Ax’ cos RB” = + 0°5 Ap’= + 0:'l 
