of a new Method of determining the Latitude. Al 
“ Having had frequent opportunities, during my residence in 
France, of seeing a great many repeating reflecting circles, several 
of which I observed with, and having found much consistency in 
the results deduced from observations made with them; it oc- 
curred to me, that if I could engage Mr. Troughton to execute 
one for me, it would be a most perfect instrument.” This was 
done, it appears from the General’s memoir, previous to the 8th of 
November 1817, and since, the latitude deduced is about 50° 20. 
We believe the observations had been made in France. The 
General pays a just tribute to Mr. Troughton as an artist, and 
then adds, “I beg to be permitted to be a little more particular 
than I otherwise should, as to the manner I have pursued in cal- 
culating and deducing the latitudes from the instrument, as it is 
not by any méans as yet generally known in England, although 
I have no doubt that when quite understood it wil be found to 
surpass all other instruments of its size, for simplicity and accu- 
racy; and I am desirous that amateurs may profit from the ex- 
perience I have had for some years of its utility.” 
“In the communication which,” says he, page 101, ‘I had the 
honour to submit to the Royal Society of Edinburgh, on the sub- 
ject of ascertaining time with accuracy, and which was read on the 
2d of February 1818,” [and it may be added, printed in 5 
and which Mr. Riddle acknowledges having seen in his commu- 
nication, page 364, vol. Ivii. Phil. Mag.,] ‘* I intimated my in- 
terition, if that was deemed worthy of a place in the ‘Transactions, 
to transmit a memoir on the repeating circle, which I now beg 
leave to lay before them,” &c. 
Here then it appears that General Brisbane had been in the 
habit of using this method, and had also published it before Mr. 
Riddle had said any thing about it, and the memoirs which fol- 
lowed were merely a continuation of the same, or a somewhat 
similar method. Ih the mean time Mr. Riddle says he thought 
it probable (and we are bound to believe him) that his method 
was the very same as that intimated by General Brisbane, and 
lays claim to the invention as a new method of determining the 
latitude. ‘* The method of General Brisbane is more like mine,” 
says Mr. R. “than I was likely to anticipate, as it is absolutely 
the same both in principle and in all its practical details.” In- 
deed Mr. R. has alreddy told us, page 364, as soon as Ge- 
neral Brisbave’s method for ascertaining time came to his know- 
ledge, that their methods were the same; and I[ must take 
Mr. R.’s word of honour that he practised that method before, 
or at the time General B. published his method; otherwise I 
should likely have insinuated that he (Mr. R.) did not practise 
this method till General Brisbane made it public, which seenis 
to have induced Mr. R. to publish this method of ascertaining 
Vol. 58. No. 279, July 1821. F the 
