5 44 M. de Zach’s Agronomical Obfervations, 
Obfervations of Jupiter’s fatellites at Marfeilles* 
OO 
*~s 
Apparent 
Obferva* 
time. 
tion. 
April 3 
Immerfton of the tit fatellite at 
h. 
2 
/ // 
22 56 
good 
May 19 
Imm. lit fat. 
' ;■> ■ ■ ! 
2 
48 12 
good 
June 7 
Imm. IVth fat. was 
not total, but its light diminilhed fenfibly without 
ever difappearing ; 
the Iky was ferene, and Jupiter had fix 
belts very 
diftinftly. 
20 
Emerfion of the lit fatellite 
1 
29 46 
good 
Ju ! ' y s 
Em. Ift fat. 
. 
1 1 
43 59 
good 
Em. lid lati 
. 
9 
17 28 
good 
2-0 
Em. Hid fat. 
- • 
9 
27 13 
good 
20 
Em. lid fat. 
M A 
1 1 
5 1 59 
good 
21 
Em. I'ft fat. 
- 
10 
1 11 
good 
2 7 
Imm. Hid fat. 
« im m 
10 
40 33 
good 
Aug. 6 
Em. Ift fat. 
- 
8 
21 20 
good 
13 
Em. Ift fat. 
- 
10 
18 49 
good 
14 
Em. lid fat. 
- 
8 
55 39 
good 
Sept. 1 
Em. Illd fat. 
_ 
9 
40 44 
doubtful 
1 14 
Em. Ift fat. 
%m ~>m — 
8 
6 48 
good 
IT is known, that the indirect method to calculate the orbits 
of comets in a conic feftion, by means of three obfervations 
given, is rendered more eafy and expeditious if there is a poffi- 
bility of drawing a graphical figure that reprefents nearly the 
orbit under confideration, by means of which the calculation 
is directed, and the required elements of the comet’s path may 
be rigoroufly determined. To draw the orbit of a comet that 
moves in a parabola or ellipfis, the problem is reduced to find 
the pofition of the axis and the perihelial diftance ; this pofi- 
tion of the axis will be determined as foon as the angle is 
known, that the axis forms with another line, whofe pofition 
is given ; this line may be an ordinate to a given point of the 
curve, or a tangent, or a radius vedlor, &c. The latter is to 
n be 
