252 
On the Longitude of Benares, as determined 
£May 
gj ea t care, the whole of the Benares and Calcutta series, for our mutual satisfaction. 
My friend G. is so well pleased with the results, that he writes in strong recom- 
mendation of the method : — 
“ J think you will ag ree with me, that two observers, with good transits and clocks or 
watches, and attending- to nothing- else but the moon and stars, for the period even of a 
week or fortnight, would deduce a far better difference of longitude, and much closer 
observations, than from a whole year’s sig-hts of Jupiter’s Satellites ; for the thirteen 
oosevrations I have compared, in two instances only, differ half a second from the 
mean ; as you will perceive by deducting- the longitude of Benares from that of Cal- 
cutta ; and the greater part of them do not vary above a single mile in space, which i9 
certainly nearer than Jupiter’s Satellites give, even by the best telescopes and ob- 
servers in the finest weather.” 
In Table I. I have given the series of observations at Benares and in Calcutta, 
whence the calculations of Table II. have been made. I worked them out roughly 
myself, by means of a single formula, finding first the exact Greenwich time of the 
observed passage of the moon’s centre, and then calculating the right ascension 
. the moon and sun, for the same moment , from the Nautical Almanack. I have 
inserted the differences of the observed and calculated transits, as found by mv- 
selt, in the second column, by the side of those deduced from the more laborious 
calculations of G., to which latter the chief reliance must be given, and which alone 
are used in the subsequent computations of the longitudes in columns 3, and 6. 
it is necessary to point out that my observations were entered in mean time, 
whereas those of Calcutta were given to me, with the apparent time duly worked 
in- i aVe not tlon b r,lt 11 wortl1 while to make the alteration. 
Of the Benares series, seventeen are esteemed good, five are indifferent, and 
t nee only are rejected : of these, one was marked as uncertain by myself, whereas 
the others are entered as good observations:— perhaps some error has found its 
way into the register or the calculation. 
Supposing the moon’s place, as given by the Nautical Almanac, to be correct, the 
longitude of my observatory at Benares, from the seventeen best observations 
marked a, will be found, . 5 u 31 n, 55v2 
fiotn twenty- two, or including the five observations b , 5 31 57 
I he discrepancies in the first set, extend to about four miles, or half a second in the 
observations : those of the b’s to nearly double that amount. As my observatory 
0 ! a s S .f reC D Se ^ b \ U * the Hind “ observatory, the latter will stand in Long. 5>> 32«* 
01 .2. By Reuben Burrow, it is 5 h 31 lu 59 s . 
. ^ 1,e Calcutta Longitudes, calculated also from the Nautical Almanack and re- 
vfs \? S tijc observations of the 6'th June and 1st November, have a mean of 5 h 53“ 
?fp J ’ d fers, 16-9 seconds from the position of the Surveyor General's office 
m Paik -treet Chowringhee, as estimated from Reuben Burrow’s Longitude 
of Rasapagla 5 53"* 30 s . The approximate longitude of the office, as found^rom 
othei sources, up to the period of the lunar transits, was only 5 h 53m 1G S 31 
trull. U 9lm^T n ml S ° f * neridi “» 1 rejecting the four observations widest ’of the 
tiulli, is -1 4b c .6. The extremes differ 33 seconds in time, “ which is less than the 
co temporary observations at the Royal observatories of Greenwich and Paris made 
under the most favorable circumstances, with large and accurate instruments i’” By 
wou1rhe2i™V differeftCC ° f meridianS ^ COrrected of obs^tionl 
piter’^VuefiL 1823 ' 2 ?’ \ pub !*f icd H series of observations of the Eclipses of Ju- 
piter & Satellites, made also with a view to determine the longitude of Benares and 
to r ountfor • ta «r d, ; screpancy *»& 
th " inwwchr "^ 
Mean of 10 Immersions I. Satellite by the Conn. Terns. 
10 Immersions, ditto, 
™ ° ( f J 1 bum. and Em. II. Satellite, by Nautical Almanack , 
Mean of 5 Ini in. and Em. III. ditto, 
Mean or 15 coincident observations at Madras, 
Mean of 5 coincident observations at Bushey Heath, 
nr . , Mean of the whole, 
Mean, rejecting the II. and III. Satellites, 
the Th L? reHteS 5 vari . ation fr om the mean (for t 
strengthened bv th^rn? WaS sufficient accordance among these, 
otnened by the comparative sights of Madras and Bushey Heath, to warrant 
1 Does not this prove too much ?— -Ed, 
li m 
5 31 
31 
32 
32 
31 
31 
5 
5 
5 
5 
5 
s 
37.7 
33.0 
13.9 
28.4 
43.9 
38.3 
5 32 52.03 
5 31 38.38 
first Satellite) was 28 s — 
accordance among these, 
