SECOND COMET OF 1822, MADE AT RIO DE JANEIRO. 
5 
June 24th. Clear weather ; moonlight. The following distances were taken 
at 6 h 30 m p.m. : 
From a Hydree 18 5/ 25 
a Crucis 46 37 30 
June 25th. Saw the comet ; but owing to the clear moonlight, it was too 
faint to be observed with the sextant. 
June 26th. Dark cloudy weather, with rain and thunder. 
June 27th. Rainy weather. In the evening, fine weather ; comet not seen. 
June 28th. Cloudy evening. 
June 29th. Fine clear moonlight ; could not discover the comet. 
On my attention being called to this comet during the last year, more than 
seven years after I had observed it, I placed the above observations in the 
hands of Mr. Thomas Henderson, of Edinburgh, who has furnished me with 
the following remarks, which I transcribe verbatim, and request you will com- 
municate to the Royal Society in the same manner. 
“ From the observations,” says Mr. Henderson, “ made at Rio de Janeiro, 
by Captain Robertson and Lieutenant Drinkwater, on the second comet of 
1822, I have obtained the following position of that comet referred to the 
ecliptic, and cleared of the effect of refraction, but not of parallax, aberration, 
nutation, or precession. Those positions have been adopted which represent 
the observed angular distances with the minimum of error, as found by the 
method of least squares. 
Mean solar 
time at Rio 
de Janeiro. 
June 1822 . 
Apparent 
longitude. 
Apparent latitude. 
d h m 
18 6 40 
19 6 40 
22 7 0 
23 6 34 
24 6 30 
O / // 
93 39 26 
125 15 42 
147 5 5 
149 31 36 
150 48 47 
73 51 6 South 
66 42 19 
47 30 47 
43 49 20 
40 39 58 
“ The errors of observation, on the differences between the observed and com- 
puted angular distances, do not exceed five minutes of space, except on the 
