156 ABSTRACTS FOR THE TOTAL INTENSITY. 
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TABLE XXIX.—Monthly Mean Values of R’ the Differences of Total Magnetic Intensity, in parts of the 
whole force, for the Observation Hours of 1842; deduced from Tables X. and XVIII., the value fo 
December 20" being taken as Zero. 
| Mean of the Be 
Month. 20%, 23h, 2s, 5h, | Four Hours. || For each |For each Two 
| | Month. Months. 
January 0-00208 0-00214 0-00220 0-00227 0:00217 || 0-00019 
February | 0-00191 0-00196 0-00200 0-00208 | 0-00199 0-00017 — 
March | 0-00140 0-00146 0-00147 0.00172 | 0-00151 0-00032 o-c60z8 
April | 0-00131 0-00121 0-00130 000168 | 0:00137 0-00047 4 
May | 0-00132 0-00110 0-00121 0.00180 | 0-00136 0-00070 ee 
June 0-00107 0-00099 0-00108 000136 | 0-00112 0-00037 
July | 0-00094 0.00046 0:00055 0-00125 || 0-00080 0-00079 wiki: 
August | 0-00067 0-00052 0-00064 0-00086 | 0-00067 0-00034 babes 
September | 0.00049 0-00050 0-00076 0-00095 | 0-00067 0.00046 pec 
October 0-00032 0-00035 0-00045 0-00067 | 0-00045 0-00035 era 
November | 0-00016 0-00028 0 00044 0-00049 | 0-00034 0-00033 ae 
December 0:00000 0-00005 0-00016 0-00019 0-00010 0-:00019 augue 
This Table has been computed from the formula aa = sin? 0 Ax + cos? A= A 
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TABLE XXX.—Mean Values of Sat for Three Months, for the Summer and Winter Months, and for the 
Year 1842. 
Period. 23h, : : Range. Mean of the 
| Four Hours. 
1842. 
Jan., Feb., March 0-00150 0-00185 0-00189 0-00202 | 0.00022 0-00189 
April, May, June 0-00123 0-00110 0-00120 0-00161 0-00051 0-00128 
July, Aug., Sept. | 0-00070 0-00049 0-00065 0:00102 0-00053 0-00071 
Oct., Nov., Dec. | 0-00016 0-00023 0:00035 0-00045 0-00029 0-00030 
Jan., Feb., March, 
Oct., Nov., Dec. } 
April, May, June, 
July, Aug., Sept. J 
The Year 0-00097 0-00092 0-00102 0-00128 0-00036 0-00105 
0-00098 0:00104 0-00112 0-00123 0:00025 0-00109 
0-00096 0-00080 0-00092 0-00132 0.00052 0-00100 
A maximum of total intensity probably occurs in the winter months before 234, and a minimum between 
23" and 2". 
The maximum seems to occur earlier in the summer months, and the minimum nearer 23" than 2, 
The total intensity decreases from quarter to quarter, the rapidity of decrease diminishing rather regularly. 
