ERRATA AND ADDENDA. 
Page 15, line 13, dele comma. 
31, 16. The formula here referred to is, 
P - ** + ^ + f * + &C - 
3 at + a' t 1 + a" t" + &c. 
where a, a', a!', & c. are the Angles observed to be described in all the respective in- 
tervals of time between every two observations, which intervals are t, t', f, &c. the 
angles being reckoned in degrees and decimals, the intervals in years and decimals. 
This value of P (the periodic time) makes the sum of the squares of the errors of 
Page 78, line 1 5, for 6o°, read 62°. 
124, — 10, for Mean, read Near. 
301, 302, 3C3, for a. Serpentis, read d Serpentis. 
210, line 11, from bottom, for position, read spaces. 
292, Note on 70 Ophiuchi, added during the printing. By fifteen observa- 
tions made at Passy, by Mr. South, in April and May of the present year, the 
angle of position at the Epoch 1825.31 was 53 0 17' or 53°.3, giving an apparent 
motion of io°.i in 2.0 years since the last observations in 1823, or 5°.050 per 
annum. This serves to render our observations of 1822 and 1823 yet more unac- 
countable, though it is still not easy to believe them erroneous, having been made 
with the greatest care. Mean while, if we take the whole interval from 1821 to 
1825, the assemblage of our observations gives 3°.552 for the mean annual motion, 
so that the retardation of velocity noticed in p. 291 is on the whole satisfactorily 
-confirmed. The distance remains nearly unchanged. 
Plate IV. Fig. 4 ,for Bassel, read Bessel. 
a t 4- cl t' -f- &c. 
t l 4- t‘ z + &c. 
From the Press of 
TV. NICOL, 
Cleveland-row, St. James's, London. 
