LIEUT.-COLONEL SABINE ON TERRESTRIAL MAGNETISM. 



17 



Sabine 



Account of the Euphrates 

 Expedition. App. 



Needle L (3)' 



Needle L (4) 



Needle E (1) 



Needle E (4) 



Needle FitzRoy's. Voyage of the Beagle. App. 



Needle (3) Phil. Trans., 1840. Art. IV. 



Needle R L (4) Brit. Assoc. Report, 1838. 



Needle 

 Needle 

 Needle 

 Needle 

 Needle 

 Needle 

 Needle 

 Needle 



. 0) 



. (2) 

 . (3) 

 . (A) 

 . (C) 

 (3B) 



. (1) 

 (3) 



>Trans. Am. Phil.Soc, 1836. 



NeedleLozenge r^'^' ^^ans., 1836. Art. XIX. 



Needle 

 Needle 

 Needle 

 Needle 

 Needle 



II 



II M^m de L' Acad. Roy. de 

 II J Bruxelles, torn. xiii. 



1 1 Trans. R. S. Edin., vol. xiv. 

 Flat/ 



•00026 



Whence, ' \ ' 



T' = T [1 + ^00026 (60° - t)], 



in which T is the time of vibration at any station, t the actual temperature in degrees 

 of Fahr., and T' is the equivalent time at the temperature of 60°. 



The application of this correction gives the "corrected time" in Table V. In the 

 few cases where the rate of the chronometer exceeded an insignificant amount, a 

 correction for the rate is also included in the " corrected time," and a memorandum 

 of the rate itself is inserted in the column of remarks. 



Table V. contains an abstract of the observations at the different stations with the 

 needles which have been specified : it includes every observation recorded to have 

 been made with these needles between the 16th of March 1839 at Panama, and the 

 22nd of March 1840 at Bow Island, except, 1st, two incomplete observations, one 

 with No. 11. at Fort Vancouver, and one with No. 13. at San Francisco, in which 

 either the vibration was interrupted, or the needles came to rest, before the usual and 

 requisite number of vibrations had been made; and 2nd, some observations at Tepic in 

 the neighbourhood of San Bias and at Mazatlan, in which the needles, for the sake 

 of experiment, were vibrated in air artificially heated, or alternately in the sun and 

 in the shade. 



MDCCCXLI. D 



