xlviii 



Geneeal Results or the Makerstoun Observations. 



Table 42. — Means of the Positive and Negative Departures of the Daily Means from the Monthly 

 Means of the Vertical Component of Magnetic Force, with their Differences. 



Month. 



Mean Positive 



! Departures. 



Mear 



Negative Departures. 



1 



Diff. of 



Mean 



Depart. 



Mean Departures, without refer- 

 ence to Sign. 





























1844. 



1845. 



1846. 



Mean. 



1844. 



1845. 



1846. 



Mean. 



1844. 



1845. 



1846. 



Mean. 



Prefix. 



0-00 



0-00 



0-00 



0-00 



0-00 



0-00 



(H)0 



0-00 



0-00 



(H)0 



(WM) 



0-00 



(MW 



Jan. 



0068 



0112 



Olio 



0097 



0128 



0164 



0138 



0143 



1-0046 



0089 



0133 



0122 



0115 



Feb. 



0140 



0134 



0167 



0147 



0119 



0097 



0142 



0119 



+ 0028 



0123 



0112 



0153 



0129 



Mar. 



0109 



0048 



0098 



0085 



0175 



0077 



0079 



0110 



-0025 



0135 



0059 



0088 



0094 



April 



0079 



0090 



0098 



0089 



0107 



0171 



0099 



0126 



-0037 



0091 



0118 



0099 



0103 



May 



0124 



OHO 



0104 



0113 



0155 



0176 



0088 



0140 



-0027 



0138 



0136 



0095 



0123 



June 



0091 



0082 



0123 



0099 



0162 



0088 



0144 



0131 



-0032 



0117 



0084 



0133 



0111 



July 



0092 



0098 



0191 



0127 



0115 



0091 



0127 



0111 



+ 0016 



0102 



0094 



0153 



0116 



Aug. 



0084 



0090 



0161 



0112 



0078 



0168 



0116 



0121 



-0009 



0081 



0117 



0135 



0111 



Sept. 



0066 



0124 



0292 



0161 



0118 



0144 



0183 



0148 



+ 0013 



0085 



0133 



0225 



0148 



Oct. 



0117 



0114 



0158 



0130 



0126 



0084 



0172 



0127 



+ 0003 



0121 



0097 



0165 



0128 



Nov. 



0115 



0109 



0168 



0131 



0084 



0194 



0112 



0130 



+ 0001 



0097 



0140 



0134 



0124 



Dec. 



01)3 



0209 



0053 



0125 



0070 



0167 



0105 



0114 



i+0011 



0087 



0186 



0071 



0115 



Table 43. — Mean Diurnal Range of the Vertical Component of Magnetic Force, as deduced from 



the Ordinary Daily Observations. 



Year. 



Jan. 



Feb. 



March. 



April. 



May. 



June. 



July. 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



Mean. 



Prefix. 

 1843 

 1844 

 1845 

 1846 



0-00 



0330 

 0481 

 0812 

 0251 



0-00 



0374 

 0584 

 0630 

 0310 



0-00 



0480 

 1202 

 0849 

 0501 



0-00 



0684 

 1164 

 0859 

 0811 



0-00 



0562 

 0830 

 0662 

 0876 



0-00 



0396 

 0433 

 0461 

 0681 



0-00 



0490 

 0522 

 0537 

 1096 



0-00 



0473 

 0944 

 0797 

 1204 



ooo 

 0502 

 0936 

 0924 

 1445 



o-do 

 0444 

 1058 

 0601 

 1098 



0-00 



0305 

 1034 

 0497 

 0871 



0-00 



0364 

 0489 

 0504 

 0332 



0-00 



0450 

 0806 

 0678 

 0793 



1843) 

 1846) 



0290 



0342 



0490 



0747 



0719 



0538 



0793 



0838 



0973 



0771 



0588 



0348 



0621 



1844) 

 1845/ 



0646 



0607 



1025 



1011 



0746 



0447 



0529 



0870 



0930 



0829 



0765 



0496 



0742 



Mean) 

 of all / 



0468 



0474 



0758 



0879 



0732 



0493 



0661 



0854 



0952 



0800 



0677 



0422 



0682 



91. Annual Variation of the Diurnal Hang es of the Vertical Component of Magnetic Force. — From the num- 

 bers in Table 43, it appears, that the diurnal range of the vertical component is greatest at the equinoxes, and 

 that it is least at the solstices. The values in Table 43 are deduced from the ordinary daily observations in 

 the various years. When we consider the diurnal ranges fi'om all the observations made in each of the years 

 1844 and 1845 (in the manner already noted for the magnetic decHnation No. 12), we obtain the following 

 means for the several months in each year, (prefix 0-00.) 



Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. Mean. 



1844, 0496 0729 1373 1327 0964 0442 0545 1064 1050 1171 1182 0522 0905 



1845, 0943 0686 0934 0924 0697 0464 0546 0820 0961 0634 0540 0560 0726 



Mean, 0719 0707 1153 1125 0830 0453 0545 0942 1005 0902 0861 0541 0816 



These means give the same law as has already been deduced from Table 43 ; the values are greater than 

 those for the same years deduced from the ordinary daily observations, but the increase is considerably less 

 than in the cases of the magnetic declination and liorizontal component. 



