236 



Abstracts of the Makerstoun Observations, 1843. 



Besides the occurrence of some considerable disturbances, tlie number of observations seems too few to 

 exhibit the secondary maximum and minimum well. The results for the principal maximum and minimum are 

 the same as those deduced from Table XI. It may perhaps be added, as true for both, that the principal mini- 

 mum occurs nearer noon in winter and summer than at the equinoxes. 



The secondary minimum occurs near midnight in the mean for the months about the winter solstice ; per- 

 haps about the same time in the mean for the months about the equinoxes, but tliis part of the diurnal curve 

 is very irregular from disturbances ; the secondary minimum cannot be said to be at all visible in the mean for 

 the months about the svimmer solstice, and it is very imperfectly shewn in the means for the year. 



The secondary maximum occurs about 6 a.m. in the winter solstitial and equinoctial months, and perhaps 

 earlier in the means for the year. 



Ranges op the Monthly Means of the Diurnal Variations of the Horizontal Component 



OF Magnetic Force. 



The quantities given in the last column of Table XI. are rather less than the true ranges, the minimum 

 occurring near 23''. The least diurnal i-ange is that for December, and the greatest that for July. The range 

 is nearly constant for the winter months, and also for the summer months, the most rapid increase occurring 

 at the equinoxes ; the following means will exhibit the rate of increase : — 



Jan. & Dec. Feb. & Nov. ]\Iarch & Oct. April & Sept. May & Aug. June & July. 



Ranges, 0-000627 0-000727 0-001473 0-002244 0-002641 0002842 

 Differences, 0-000100 0-000746 0-000771 0-000397 0*000201 



The range of the monthly means is more than four times as great for the summer as for the winter months. 



I 



TABLE XIII. — Diurnal Ranges of the Hoi^izontal Component of Magnetic Force for each Civil Day, 



as deduced from the 9 Daily Observations in 1843, with the Weekly and Monthly Means. ■ 



Civil 

 Day. 



January. 



February. 



March. 



April. 



j\Iay. 



June. 



July. 



August. 



September. 



October. 



November. 



December. 





0-0 



0-0 



0-0 



0-0 



0-0 



O'U 



o-n 



0-0 



0-0 



0-0 



0-0 



0-0 



1 



[ ] 



0067 



0046 



0214 



0231 



0322 



0385 



0266 



0328 



[0220] 



0194 



0116 



2 



0067 



0045 



0109 



[0389] 



0249 



0308 



[0344] 



0230 



0375 



0206 



0192 



0215 



3 



0127 



0092 



0091 



0190 



0213 



0207 



0378 



0461 



[0294] 



0175 



0237 



[0124] 



4 



0089 



0070 



0113 



0215 



0198 



[0271] 



0395 



0696 



0278 



0204 



0169 



0067 



5 



0111 



[0104] 



[0172] 



1265 



0302 



0285 



0251 



0319 



0278 



0261 



[0162] 



0110 



6 



0173 



0162 



0174 



0515 



0939 



0229 



0224 



[0425] 



0281 



0212 



0097 



0154 



7 



0029 



0172 



0346 



0207 



[0447] 



0272 



0289 



0287 



0217 



0240 



0155 



0097 



8 



[0138] 



0085 



0199 



0391 



0476 



0278 



0412 



0255 



0265 



[0226] 



0124 



0259 



9 



0227 



0088 



0189 



[0331] 



0288 



0224 



[0330] 



0528 



0405 



0239 





0242 



10 



0104 



0092 



0139 



0197 



0482 



0302 



0442 



0427 



[0252] 



0182 





[0199] 



11 



0187 



0142 



0169 



0289 



0275 



[0295] 



0281 



0311 



0213 



0222 



0102 



0305 



12 



0079 



[0132] 



[0166] 



0388 



0256 



0417 



0337 



0294 



0231 



0189 



[0142] 



0141 



13 



0062 



0182 



0242 



0292 



0170 



0361 



0330 



[0289] 



0182 



0149 



0213 



0149 



14 



0120 



0144 



0124 



0340 



[0281] 



0188 



0290 



0285 



0144 



0277 



0153 



0070 



15 



[0097] 



0146 



0136 



0362 



0366 



0307 



0231 



0222 



0132 



[0274] 



0103 



0045 



16 



0099 



0149 



0219 



[0317] 



0333 



0285 



[0275] 



0196 



0152 



0567 



0114 



0043 



17 



0140 



0090 



0182 



0332 



0287 



0321 



0259 



0239 



[0200] 



0196 



0109 



[0058] 



18 



0078 



0139 



0335 



0355 



0274 



[0303] 



0281 



0213 



0183 



0267 



0119 



0102 ' 



19 



0098 



[0117] 



[0217] 



0223 



0202 



0348 



0256 



0251 



0370 



. 0182 



[0101] 



0028 i 



20 



0083 



0115 



0143 



0193 



0280 



0294 



0212 



[0282] 



0220 



0242 



0099 



0061 1 



1 



.1 



