Abstracts for the Magnetic Declination. 



137 



TABLE II. The Monthly Means of the Declinometer Keadings, rejecting disturbances, in Westerly Declination, 



for the Hours 20, 23, 2, and 5. 



Month. 



201'. 



23h. 



21-. 



5h. 



Mean of 

 201- and 51-. 



Range. 





25" 



25° 



25° 



25° 



25° 





1841. 















July 



26.42 



30-74 



35-14 



32-78 



29-60 



8-72 



August 



33-68 



37-32 



42-55 



38-09 



35-88 



8-87 



September 



30-23 



33-34 



38-35 



34-23 



32-23 



8-12 



October 



29-21 



31-10 



33-90 



31-01 



30-11 



4-69 



November 



30-55 



31-44 



33-83 



31-60 



31-07 



3-28 



1842. 















January 



27-96 



28-47 



30-77 



29-25 



28-60 



2-81 



February 



29-25 



31-19 



34-91 



32-48 



30-86 



5-66 



March 



27-53 



30-98 



35-43 



31-52 



29-52 



7-90 



April 



31-06 



34-34 



39-73 



35-73 



33-39 



8-67 



May 



25-50 



30-50 



35-79 



32-57 



29-03 



10-29 



June 



24-94 



29-25 



34-92 



33-31 



29-12 



9-98 



July 



25-13 



28-65 



34-08 



31-98 



28-55 



8-95 



August 



24-18 



29-73 



33-53 



28-80 



26-49 



9-35 



September 



26-68 



30-99 



34-06 



28-92 



27-80 



7-38 



October 



25-90 



28-32 



32-75 



28-81 



27-35 



6-85 



November 



26-58 



27-92 



3002 



26-98 



26-78 



3-44 



December 



24-88 



25-94 



27-31 



25-54 



25-21 



2-43 



Each month shews markedly an increase of Westerly Declination from 20'' till 2^, and a decrease from 2'^ 

 till 51^. 



The means cannot be trusted for indications of an annual period. The diurnal range, however, increases 

 considerably in summer compared with winter, and the ranges of the months in 1841 and 1842 agree very well. 

 The maximum range occurs in May 1842, but it seems probable that the ranges for April, June, and July, 1842, 

 are less than they should be, owing to disturbances, which have not been eliminated by the previous rule. 



The two following; Tables are formed from Table II. 



TABLE III. — The Westerly Declination at the Observation Hours for periods of Three Months, for the Summer 



and Winter Months, and for the Year 1842. 



Period. 



20i>. 



23h. 



2i. 



51". 



Mean of 

 201' and 51'. 



Range. 





25° 



2.5° 



25° 



25° 



25° 



25° 



1841. 















July, Aug., Sept. 



30-11 



33-80 



38-68 



35-03 



32-57 



8-57 



Oct. and Nov. 



29-88 



31-27 



33-86 



31-30 



30-59 



3-98 



1842. 















Jan., Feb., March 



28-24 



30-21 



33-70 



31-08 



29-66 



5-46 



April, May, June 



27-17 



31-36 



36-81 



33-87 



30-52 



9-64 



July, Aug., Sept. 



25-33 



29-79 



33-89 



29-90 



27-61 



8-56 



Oct., Nov., Dec. 



25-79 



27-39 



30-03 



27-11 



26-45 



4-24 



Jan., Feb., March ) 

 Oct., Nov., Dec. j 



2701 



28-80 



31-86 



29-09 



28-05 



4-85 



April, May, June ) 

 July, Aug., Sep. J 



26-25 



30-57 



35-35 



31-88 



29-06 



9-10 



The Year. 



26-63 



29-69 



33-61 



30-49 



28-56 



6-98 



MAG. AND MET. OBS. VOL. I. 



2m 



