Gas-Burners , and on the Illuminating Power of the Gases. 89 
of the former; while, according to Professor Leslie’s photometer, it is 2 $ 
times greater. 
Nota . — The reader will please correct, in the list of the illuminating powers of 
the gases, at the bottom of p. 31., that of Messrs Herapath and Hootsey, there 
stated as 1:2; but which, from their printed evidence before the House of 
Commons, just communicated to us, is 1 : 2,4. 
Art. II . — A Table of the Geographical Positions of several 
Places in India. By James Franklin, Captain of the 
Bengal Cavalry, and late Assistant Quarter-Master General 
of the Bengal Army. 
The following Table of geographical positions, consists prin- 
cipally of places situated in Bundelcund between the J umna and 
Nermadah Hi vers. 
The Latitudes were all obtained from actual observations 
either of meridional altitudes of the sun, or, when that object 
could not be observed, of one or more stars, taken by the me- 
thod of reflection with a sextant of nine inches radius ; and it 
was my practice always to use a chronometer in taking them, 
with a view of obtaining as many altitudes as I could get on 
both sides of the meridian within ten or twelve minutes of the time 
of transit, noting the times of each; from which, the meridional al- 
titude being readily made out, I usually had a mean of several 
to compare with the observed altitude ; and if the calculated 
and observed altitudes agreed within two or three seconds, which 
was generally the case, I adopted a mean of the whole for the 
meridional altitude. This measure, I am persuaded, contri- 
buted to accuracy, and was capable of being proved, because 
the results formed a part of the probationary operations of an 
extensive survey, the nature of which was fully adequate to the 
detection of any sensible error. The refraction was invariably 
reduced to the state of the atmosphere. 
The Longitudes, except in the instances of the chief points 
which were essential to be ascertained with great accuracy, such 
as Calpie, Keitch, &c. were taken from protraction, in prefe- 
rence to the approximations of actual observation; because, at the 
places above mentioned, the actual observations were made with 
scrupulous exactness, by multiplied observations of the eclipses 
of Jupiter’s first and second satellites, by the beginning and end 
of a solar eclipse, by transits and meridional altitudes of the 
