6 
LIEUTENANT W. ROBERTSON’S OBSERVATIONS OF THE 
23rd, when, in one observation, the error amounts to eleven minutes ; for which 
reason the position of that day is not employed in computing the orbit. 
“ The following elements of the comet’s parabolic orbit have been obtained 
by Olbers’ method of computation, founded upon the observations of June 
19th, 22nd, and 24th. 
Time of perihelion passage, mean solar time at Greenwich, 1822, July 15.651. 
Longitude of the perihelion 220 19 49 
Inclination of the orbit 35 36 0 
Longitude of the ascending node . . . 98 14 47 
Logarithm of perihelion distance . . . 9.92879 
Motion retrograde. 
“ The following are the errors of the places computed from these elements, 
or the corrections to be applied to the computed places, in order to obtain 
those which were observed. 
Longitude. 
Latitude. 
June 18 . 
/ * 
. . . - 7 • • 
. . +1 
19 . 
. . . + 5 . . 
. . + 1 
22 . 
... 0 . . 
. . - 1 
23 . 
. . . +15 . . 
. . +5 
24 . 
... 0 . . 
+ 1 
“ The greatest error is on the 23rd; the observations of which day, for the rea- 
sons already stated, are supposed not to be so exact as those of the other days. 
The other errors, it may be remarked, are not greater than what might have 
been expected from the uncertainty of the observations, and great latitude of 
the comet, when the errors in longitude are apparently much increased, from 
being reckoned upon a small circle. 
“ On comparing the foregoing elements, computed from Captain Robertson 
and Lieutenant Drinkwater’s observations, with those deduced by M. Hulin- 
genstein from the observations made in Europe, referred to at page 2, it 
will be seen that the differences between them are wonderfully small, con- 
sidering the different instruments used by the observers in the two hemi- 
spheres. 
“ The elements, placed side by side, stand thus : 
