PHILOSOPHICAL TRANSACTIONS. 
I. Observations of the Second Comet of 1822, made at Rio de Janeiro. By 
Lieutenant (now Captain) William Robertson, R.N. Communicated in a 
Letter to Captain Basil Hall, F.R.S. 
Read June 17, 1830. 
I SHALL feel obliged to you to lay before the Royal Society the following 
observations, which, with the assistance of Lieut. Charles Drinkwater, R.N., 
I made upon the “ second comet of 1822,” as it is called. They were made at 
Rio de Janeiro, when I was Lieutenant of His Majesty’s ship Creole, under 
the orders of Commodore Sir Thomas Hardy ; but as the means I had in my 
possession for making such nice observations were not great, I did not imagine 
the results could be of much value, till I accidentally gained information of 
the following remarks in Baron Zach’s Journal, vol. vi. page 596. 
“ Cette comete, comme nous l’avons dit dans notre V me cahier, page 481, n’a 
ete que tres peu observee, a cause de son mouvement fort-rapide en declinaison 
australe ; elle s’est par consequent bientot soustraite a nos regards, pour se 
montrer peut-etre avec plus d’eclat aux antipodes. Nous n’avons regu d’autres 
observations que celles que nous avons deja publiees dans notre cahier prece- 
dent. Probablement 1’orbite de cet astre passager nous restera inconnue pour 
toujours, a moins que MM. Fallow, Rumker, ou un autre Basil Hall, ne 
parviennent a l’observer dans l’hemisphere austral. Mais la correspondence 
astronomique des deux hemispheres n’est pas encore bien etablie 
The above allusion to your observations on the comet which we observed 
together at Valparaiso in 1821, and which are published in the Philosophical 
* Correspondence Astronomique du Baron Zach, vol. vi. p. 595. 
B 
MDCCCXXXI. 
