XXXIV 



General Results of the Makerstoun Observations. 



Table 25. — Means of the Positive and Negative Departures of the Daily Means from the Monthly 

 Means of the Horizontal Component of Magnetic Force, with their Diiferences. 



Month. 



Mean Positive 



Departures. 



Mean 



Negative Departures. 



Diff. of 

 Mean 

 Depart. 



Mean Departures, without refer- 

 ence to Sign. 





























1844. 



1845. 



1846. 



Mean. 



1844. 



1845. 



1846. 



Mean. 



1844. 



1845. 



1846. 



i 



Mean. 



Prefix. 



0-00 



o-no 



n-oo 



o-ou 



0-00 



O-no 



000 



0-00 



0-00 



0-00 



O'OO 0-00 i 



0-00 



Jan. 



0172 



0316 



0159 



0216 



0215 



0538 



0171 



0308 



-0092 



0191 



0398 ' 0165 



0251 



Feb. 



0317 



0303 



0284 



0301 



0404 



0303 



0171 



0293 



+ 0008 



0356 



0303 1 0213 



0291 



Mar. 



0445 



0214 



0299 



0319 



0712 



0250 



0299 



0420 



-0101 



0548 



0231 



0299 



0359 



April 



0404 



0285 



0314 



0334 



0472 



0641 



0428 



0514 



-0180 



0436 



0394 



0362 



0397 



May 



0355 



0228 



0346 



0310 



0330 



0387 



0403 



0373 



,-0063 



0342 



0287 



0372 



0.334 



June 



0193 



0177 



0441 



0270 



0178 



0225 



0514 



0306 



-0036 



0185 



0198 



0475 



0286 



July 



1 0217 



0204 



0314 



0245 



0271 



0297 



0393 



0320 



-0075 



0241 



0242 1 0349 



0277 



Aug. 



0353 



0386 



0393 



0377 



0380 



0241 



0288 



0303 



+ 0074 



0366 



0297 \ 0332 



0332 



Sept. 



0248 



0315 



0463 



0342 



0316 



0315 



0540 



0390 



;-0048 



0278 



0315 



0499 



0364 



Oct. 



0459 



0285 



0345 



0363 



0194 



0307 



0586 



0462 



'-0099 



0476 



0296 



0434 



0402 



Nov. 



0280 



0330 



0496 



0369 



0382 



0357 



0390 



0.376 



-0007 



0323 



0343 



0437 



0368 



Dec. 



0258 



0358 



0311 



0309 



0413 



0608 



0335 



0452 



-0143 



0318 



0451 



0323 



; 0364 



1 



59. The following are the conclusions from Table 25. 



1st, The daily mean value of the horizontal component is both most in excess and most in defect of its 

 monthly mean value in April, and in the months from August to November ; while the smallest departures 

 from the monthly means occur about the solstices. 



2rl, The average negative departure is greater than the average positive departure, in every month of the 

 year with two exceptions, February and August, and the excess of the former over the latter is greatest in April 

 and December. 



Sd, As both the positive and negative departures obey nearly the same law, we in consequence find, as in 

 the last column of Table 25, that the greatest departures of the daily means from the monthly means occur 

 immediately after the equinoxes, and the least departures immediately after the solstices. We may generalize 

 this result (as in the case of the magnetic dcchnation, No. 11, 4th) thus : — The differences of the daily means of 

 the horizontal component of magnetic force from the monthly means were a maximum when the horizontal 

 component was least, and a minimum when it was greatest. 



Table 26. — Mean Diurnal Range of the Horizontal 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 



1396 

 1920 

 4095 

 1988 



0-00 



1567 

 2750 

 2672 

 2051 



0-00 



2333 

 4980 

 3276 

 3520 



0-00 



4102 

 4990 

 5695 

 5663 



0-00 

 4119 

 4510 

 4512 

 6711 



0-00 



3815 

 3710 

 4010 

 5886 



0-00 



4846 

 4290 

 4151 

 6807 



0-00 



4128 

 4600 

 4597 

 6750 



0-00 



3268 

 4020 

 4441 

 5986 



0-00 



2932 

 3690 

 3164 

 3947 



0-00 



1682 

 3140 

 2480 

 3597 



0-00 



1609 

 2510 

 3565 

 2048 



0-00 



2983 

 3760 

 3888 

 4579 



1843) 

 1846f 



1692 



1809 



2926 



4882 



5415 



4850 



5826 



5439 



4627 



3439 



2639 



1828 



3781 



1844) 

 1845/ 



3007 



2711 



4128 



5342 



4511 



3860 



4220 



4598 



4230 



3427 



2810 



3037 



3824 



Mean) 

 ofaUj 



2350 



2260 



3527 



5112 



4963 



4355 



5023 



5019 



4429 



3433 



2725 



2433 



1 



3802 



