99 [1% J 
oe 
. " ASTRONOMICAL OBSERVATIONS, 
“ 
“The maps which accompany this report are on Flamsteed’s modified pro- 
jection, and the longitudes are referred to the meridian of Greenwich. 
For the determination of astronomical positions, we were provided with 
the nee instruments : 
e telescope, magnifying power 120. 
One circle, by Gambey, Paris. 
me box chronometer, No. 7,810, a French. 
ne Brockbank pocket chr 
€ watch with - & ght ter balance, No. 4,632, by 
& Dent. 
~ Arno 
The rate of the ‘Sdbaallicer 7,810, is stant in the following state- 
ment 
“New Yorx, May 5, 1842. 
a Chronometer No. 7 ,810, by French, is _ 2. at noon— . 
low of Greenwich mean time ix a 
“ p= of New York mean i eae oe eee ion 4 
. ~“ Loses perddy § - . €: ah, 
=. é “~ ARTHUR STEWART, 
— “74 Merchants’ Exchange. Zz 
An accident among some rake ground i in the neighborhood of the <.. 
sas river Strained the balance of this chro onometer, (No. 7,810,) and ren- 
it useless during the remainder of the campaign. From the 9th of 
June to the 24th of August, inclusively, the longitudes depend upon the 
Brockbank pocket chronometer; the rate of which, on leaving St. Louis, 
was fourteen seconds. The rate obtained by observations at Fort Laramie, 
14".05, has been used in calculation. 
From the 24th of August until the termination of the j journey, No. 4,632 
(of which the rate was 35'.79) was used for the same purposes. The rate. 
sf this watch was irregular, and I place but little confidence in the few 
itudes:which depend upon it, though, so far as we have any means rs 
eg see ited correct.» Basi slay ys 
= 
