1867.] 



made ivith a Rigid Spectroscope. 



13 



Latitude. 



EeRcLings 

 reduced. 



1 Eeading reduced 

 and corrected 

 lor lail 01 zero. 



! Difference 

 (negative). 



Ai^o in 4-0° isr 



4--71 



'-tlx. 



•0 



rtv OO 







•13 



SO 



KJtJ tJ\J 



4-^0 



4.55 



•16 



SO 9^ 



Ov iiej 





4.-^4 



•1 7 



9t 90 

 ^yj 





4-^4 



•1 7 



90 1 ^ 

 i5U — ^-0 





4-47 



•24 



In 10 





4-4^ 



•26 



10 '^i 



4.90 





•9^ 





4-- 90 





•S9 



^ ^ 



4-90 



4-49 



• OQ 



^ 10 



4--1 Q 





•98 



10 1 ^ 



zL-99 



4-4Q 



•99 



If; 90 





4-'>4 



•1 7 



90 9t 



4.-1 « 



4--4Q 



•22 



25 — 30 



4-16 



4-56 



•15 



30 — 35 



4-13 



4-49 



•22 



35 — 40 



4-13 



4-52 



•19 



40 — 45 



4-29 



4-70 j 



•0 



On comparing the last number of the second column with the first 

 it wiU appear that there is a change in the zero of the instrument ; 

 presuming that this change took place during the voyage at the same 

 rate, we obtain column 3 corrected for change of zero, and column 4 

 representing differences. 



This residual difference, which remains after all known corrections 

 have been applied, is exhibited for the different latitudes in the follow- 

 ing diagram (fig. 1), while the observed temperatures of these latitudes 

 are also exhibited. 



rig. 1. 



South. 



In the next place, let us take the diagrams sent by Captain Mayne, 

 which exhibit the readings of the spectroscope at the various places of 



