Vea y=. 
Lieut. Drummond’s Station Light, &c. 453 
There were next read Extracts of three letters addressed 
by M. Gambart, Director of the Observatory of Marseilles, to 
James South, Esq. respecting the discovery and elements of 
the orbit of a comet, supposed to be the same with that, or 
those, of 1772 and 1805. M.Gambart first presents the sum- 
mary of his observations of this comet from the 9th to the 
2tst (inclusively) of March this year. He then exhibits the 
elements as computed from these observations upon the para- 
bolic hypothesis : viz. 
Passage of the perihelion, March 1826, 18,94 days, counting 
from midnight. 
Perihelion distance. . . 0°961 
Long. perihelion . = . 104° 20' 0” 
Long. ascend. node . . 247 54 10 
Inclination °° 2). Pe a Rigg ER) 
Motion direct. 
These elements were communicated March 23rd :—a week 
after, the elliptic elements deduced from the same observa- 
tions were transmitted, and are as follows: viz. 
Passage of the perihelion, March 1826, 19,5998 days, 
counting from midnight. 
Semi-axis major. . . . 3°567 
Excentricity . . . . . 0°74187 
Log. mean motion . . . 2°7326487 
Long. perihel. | 2+ «<'. *.*" 108° 54/19" 
Long. asc. node . . . 249 55 23 
Inclination . . . . +. + +%13 50 47 
Motion direct. 
Periodic time. . . . . . 6°567 years. 
The same elements, M. Gambart observes, represent al- 
most exactly the observations of the comets of 1772 and 
1805; whence the identity of all three is inferred. 
The reading of Mr. Herschel’s paper on Double-stars, com- 
menced at the last meeting, was continued. 
LXVII. Intelligence and Miscellaneous Articles. 
LIEUT. DRUMMOND’S GEODESICAL INSTRUMENTS. 
WE have been favoured with the following abstract of Lieut. 
Drummond’s paper on this subject, read before the Royal 
Society, on May 4th, and briefly noticed in our last No. p. 373. 
In this paper two methods are described by which geodesi- 
cal operations may be facilitated to.a very considerable extent, 
—the one applicable by day, the other by night. The first, 
which consists in employing the reflection of the sun from a 
Bae mirror as a point of observation, was first suggested by 
rofessor Gauss; and the result of the first trials made in the 
survey of Hanover proved very successful. Recourse was had 
to 
