1 576 ] 
Error of 
Difference between 
5® ao', and each 
particular error of 
account. 
account. 
1761. 
O / 
0 / 
March 9. 
4 12 
— i 8 
10. 
5 ® 
— 0 20 
13 - 
5 3 6 
-\- 0 16 
5 2 5 
+ 0 S 
35 - 
4 44 
— 0 36 
37 - 
5 5 2 
+ 0 32 
r8. 
6 7 
+ 0 47 
5 J 3 
— 0 7 
5 46 
4- 0 26 
19. 
4 34 
— 0 46 
20. 
4 5 2 
— 0 28 
6 37 
+ 1 17 
Mean error of account 
5 20 
After finding fo great an agreement in the refill t 
of all my different obfervations, whether made on the 
fame or different ffars, or on the fame or different 
nights, I muff own I find myfelf at a lofs to account 
for the great difference found by the Abbe De la 
Caille, in the refult of feveral obfervations taken by 
himfelf, and a friend of his, at land, which ought to 
agree hill nearer with one another than thofe made at 
fea. I cannot conceive that fuch able obfervers could 
be liable to an error of § / in meafuring the diffance 
of a (far from the Moon’s limb, if their inffruments 
were not faulty. The molt likely and the moff com- 
mon caufe of error lies in the fpeculums and dark 
glades > 
