48 Capt. E. Sabine's Notices occasioned by the 



latitudes observed at New York, which are amongst the most 

 remarkable instances of agreement when calculated with sin- 

 gle seconds as the value of the level, and of separation when 

 recalculated with the value of 10-9. They are as follows : 



Level, 109 Seconds. 

 40° 42' 44"-6-| r. ■ ■ , 

 40 42 47 -2 K ^™ 1 * 

 40 42 58 -4 J exlstin S- 

 40 42 38 -2 Original 

 ' not found. 



1822. 



1823. 



1822. 



Level, single Seconds. 

 Dec. 24. Sun.... 40° 42' 40"- 1 



31. Sun.... 40 42 41 -4 

 Jan. 3. B. Ursaj 40 42 42 -3 

 Dec. 24. Polaris. 40 42 48 -9 





Mean; level ) 40 4 2 43-2 

 single seconds J 



S8S>««-' 



There are also the originals of four of the six latitudes at 

 Maranham ; one of these is the observation of a Lyras, on the 

 31st of August, which is. one of the two which differ most 

 from the mean ; the others are of a Lyras, August 29th ; 

 a Cygni, August 31st; and a Gruis, September 2nd. I have 

 also found the original noting of the observation of a Lyrae, 

 at Bahia, on the 26th of July 1822, by which I am enabled to 

 correct the signs in the 7th, 8th, 10th, and 11th repetitions 

 {Pendulum Experiments, page 298), which have been incor- 

 rectly transcribed — instead of 4- ; the summing up of the 

 column ( — 5) which appears as the mean reading of the level 

 is thus seen to be correct, and the result of the observation 

 recalculated with 10*9, is 12° 59' 17", instead of 12° 59' 21", 

 as calculated with single seconds. 



The original papers to which I have referred are now in 

 Capt. Kater's possession. 



2. When transits are observed with a chronometer, and ir- 

 regularities of less amount than a beat of four-tenths of a second 

 are not taken into account in the registry, the times of passage 

 from wire to wire will be identical in a much greater number 

 of instances than when the actual time of transit at each wire 

 is estimated to the tenth of a second, and registered accord- 

 ingly, as is the case in observatories; but the latter is without 

 doubt the more exact method of obtaining the absolute time 

 of transit. My purpose, which was simply to determine the 

 rate of a clock, did not require that I should adopt the best 

 method of observing absolute transits, but merely that the 

 method adopted at the commencement should be also em- 

 ployed at the close. 



3. The purpose for which naval officers observe Lunars, is 

 usually to ascertain the position of a ship at sea; for that pur- 

 pose it is not requisite, nor is it customary, to attend to se- 

 veral particulars in respect to the instrument, the modes of 

 observation and calculation, on which precision in the re- 

 sult 



