3$ * Mr. Bugge’s Determination of 
1784 
T? culmi- 
nation, 
mean time 
at Copen. 
- 
1 ? obferved 
longitude. 
1? obferv- 
ed lati- 
tude. 
The error of 
Halley 
The error of M. 
de la Lande. 
in long. 
in lat. 
in long. 
in lat. 
h - / // 
s * 0 in 
0 ill 
/ /t 
n 
/ // 
// 
July 12 
12 3 I 
9 20 34 48 
0 3 35 B 
4-2 22 
4-32 
-9 40 
+ 33 
20 
II29 9 
9 19 59 39 
0 2 59 
4 - 2 14 
4-38 
Aug. x 
IO 38 2 
9 19 9 22 
0 i 44 
+ 1 45 
4-27 
-9 49 
4-28 
8 
IO9O 
9 18 42 56 
01 2 
4 - x 48 
4-21 
21 
9 H 59 
9 18 i 23 
00 2 
+ 1 35 
4-28 
27 
8 50 19 
9 i 7 4 6 19 
0 0 29A 
4 - 1 26 
— 26 
-9 35 
- 3 ° 
3 1 
8 33 47 
9 17 38 7 
0 0 53 
4 - 1 19 
- 2 3 
Sept. 5 
8 13 45 
9 l 7 2 9 3 6 
0 1 26 
4 - 1 20 
-25 
-9 25 
-27 
J 5 
7 33 45 
9 i 7 19 39 
02 4 
4-118 
-25 
Oft. 8 
6 4. 23 
0 17 34 61 
O 3 C 7 
4 - 1 22 
— 20 
-8 48 
-32 
\ K % 
Iii order to reduce the obferved geocentric longitude to the 
fun, or by obfervation to find the heliocentric longitude, it is 
required to know the angle at the planet = p. If this angle is 
calculated in the common way only by the tables, there will 
arife fome difference, according to the different elements and 
the different conftrudions of the tables. Thus, at the time of 
Saturn’s culmination, this angle is found the 12th of July, by 
the tables of Dr. Halley =o° f 13", and by the tables of 
M. de la Lande =o° 2' o" the 8th of Auguff by Halley 
= 2 0 35% and by M. de la Lande — 2 0 42' 34"; the 
27th of Auguff after Dr. Halley =4° 14' 15", and after 
M. de la Lande =4° if 47". To avoid thofe differences, 
which often may alter the heliocentric longitude more than 
one or two minutes, the following method may be ufeful. 
The heliocentric longitude of the earth, calculated after the 
tables of M. Mayer, is to be depended upon to eight or ten 
feconds. From the heliocentric longitude of the earth, and from 
the obferved geocentric longitude of the planet, correded for the 
aberration and nutation, is deduced the angle at the earth = t. 
2 
or 
