166 
Tr Jj. , 1; — T ; * i'-jin'J of 1771. 
Correction* to th e Ephemeris ( continued ). 
In Declination. 
1771 
Paris and elsearhere. 
Marseilles. 
Paris m. t. 
Xo. 
olse. 
Wt. 
Corr. A<5. 
Xo. 
Corr. 
Apr. 6.5 
11 
49 
+ 1' 42"±6"8 
0 
14.5 
22 
€5 
+ 1 31- ± 41 
0 
30.5 
23 
36 
+ 1 29- ± 5-3 
10 
—V 
49-" 
± 19" 
Mar 8.5 
16 
8- ± 14-3 
4 
+ 3 
27- 
4-44- 
16.5 
27 
45 
+ 6* ± 5*7 
7 
+ 
44- 
±41* 
24.5 
12 
36 
— 38- ± 6 8 
5 
— 
9- 
±17- 
June 1.5 
4 
18 
— 57* ± 4‘8 
9 
— 1 
14- 
±10- 
9.5 
3 
12 
— 1*5 ±15*0 
6 
— 
18- 
± 8- 
25.5 
0 
18 
r- 37] 
12 
— 
37- 
±65- 
Julj 11.5 
0 
15 
[- 1*1 
9 
•— 
1- 
±28- 
The Marseilles observations were not used to correct the ephemeris 
until after June 9, the date of the last reliable observation elsewhere. 
Preparatory to using the rest, an attempt was made to detect the 
presence of any systematic error by comparing the earlier part of the 
series with those more reliable. A set of ten dates was decided on, 
eight of which fell within the period embraced by the other observa- 
tions. The corrections to the ephemeris due to all the other observa- 
tions were obtained from these eight dates and compared with the 
corrections derived from the Marseilles observations, as above. 
The ephemeris thus approaches the observations in right ascension, 
nearer at the ends than in the middle ; and we might expect by July 
to find the ephemeris very near the observations. 
This would require a diminution of the corrections for June 25 and 
July 11, as derived from the Marseilles observ ations, and the excess 
of these observations for May 24 and June 1 and 9 confirms this 
opinion. Consequently the last two corrections were diminished each 
by 2' 30' . 
In declination, the same principle would lead us to expect larger 
subtractive corrections at the end than the Marseilles observations 
give ; but the*e show too many irregularities throughout to warrant 
any change. Encke made use of one observation in July, which he 
diminished by 40' in right ascension, but left unchanged in declina- 
tion, giving no reason for so doing.* The amount of the correction 
is very arbitrary, and can only be called an attempt to remove what 
seems to be a systematic excess in the Marseilles observations. 
The ephemeris corrected by the amounts given in the first of the 
two columns of corrections, including those in brackets for June 25 
and July 11, gives the following normal places. 
See Yon Zac Its Astr. Corresp., 1821, p. 557. 
