224 



Absteacts of the Makerstoun Obseevations, 1843. 



TABLE III. — Mean Westerly Declination at the Observation Hours for each Month in 1843. 



Month. 



18. 



20. 



22. 



23. 



0. 



2. 



4. 



6. 



8. 



10. 



1843. 



25° 



25° 



25° 



25° 



/ 



25° 



25° 



25° 



25° 



25° 



25° 



January 



24-29 



24-96 



24-58 





27-50 



28-95 



27-13 



25-85 



25-04 



24-03 



February 



23-94 



24-21 



24-71 





27-84 



29-41 



27-65 



25-92 



23-97 



21-06 



March 



22-65 



23-14 



22-83 





27-15 



29-78 



28-52 



25-14 



24-05 



21-85 



April 



21-36 



20-67 



22-78 





27-78 



31-19 



28-37 



24-06 



22-32 



21-45 



May 



20-76 



19-79 



21-95 





27-05 



29-72 



27-05 



24-55 



23-63 



22-54 



June 



21-69 



20-56 



23-39 





28-91 



31-70 



29-52 



26-15 



25-34 



25-00 



July 



20-44 



20-09 



22-17 





27-17 



30-04 



27-71 



25-15 



23-48 



21-42 



August 



19-80 



18-48 



21-77 





26-89 



29-31 



26-15 



22-47 



21-15 



21-26 



September 



19-48 



19-55 



20-74 





25-82 



27-51 



24-94 



21-29 



18-98 



16-76 



October 



20-97 



21-46 



21-84 





26-37 



26-67 



24-14 



21-90 



20-66 



18-77 



November 



18-55 



18-80 



18-97 



20-37 



22-02 



22-06 



20-99 



19-76 



17-93 



17-43 



December 



19-00 



19-02 



19-56 



20-53 



21-57 



22-42 



21-05 



19-73 



17-27 



16-69 



Mean 



21-08 



20-89 



22-11 





26-34 



28-23 



26-10 



23-50 



21-98 



20-69 



The above Table is intended chiefly as a key for comparing the tabular observations. 



The mean at IS*^ in Januai-y is rendered compai'able with the means at the other hours thus : the daily means 

 from January 9 to 14, being the means of 8 daily observations, were corrected by — 0'*14, obtained, as for Table I., 

 in order to reduce them to the mean of 9 daily observations, then 



Mean Westerly Declination, January 9 — 31, 

 January 16 — 31, 



Difference, 



= 25 83 

 = 26-25 



= 0-42 



The mean for 18*^, deduced from the observations January 16 — 31, was therefore corrected by — 0"'42, in 

 order to reduce it to the mean from January 9 — 31 as for the other hours. 



Secular Change. 



By comparing the means at 20^, 23'*, 2^ and 5^, the observation hours in 1842 (Table I., p. 136, 1842), 



22*^ + 0^ 4'* + 6'* 



with the means at 20'*, , 2^ and — ~ — for 1843, we obtain the following results for the yearly retro- 



gression of westerly declination : — 



201^ 



23i> 



2h 



Sk 



1842, 

 1843, 



26-61 

 20-89 



Difference, 5-72 



29-80 

 24-22 



5-58 



33-80 

 28-23 



5-57 



Mean, 



5'- 62. 



30-40 

 24.80 



5-60 



