236 ABSTRACTS OF THE MAKERSTOUN OBSERVATIONS, 1845. 
Besides the occurrence of some considerable disturbances, the 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 oceurs 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 this 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 summer 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. 
; 
I 
4 
® 
RANGES OF 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 
oceurring near 23", The least diurnal range 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. March & Oct. April & Sept. May & Aug. June & July. 
Ranges, 0:000627 0:000727 0001473 0:002244 0:002641 0002842 
Difierences, 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. 
TABLE XIII.—Diurnal Ranges of the Horizontal Component of Magnetic Force for each Civil Day, i 
as deduced from the 9 Daily Observations in 1843, with the Weekly and Monthly Means. i 
Civil 
Day January. | February.| March. April. May. June. duly. August. |September.| October. | November.| December, 
oo 0-0 0-0 oo 0-0 ovo 0-0 0-0 oO 
1 || [----] | 0067 | 0046 | 0214 | 0231 | 0322 | 0385 | 0266 | 0328 | [0220] | 0194 
2 | 0067 | 0043 | 0109 | [0389] | 0249 | o308 | [0344] | 0230 | 0375 | 0206 | 0192 
3 | 0127 | 0092 | oo91 | 0190 | 0213 | 0207 | 0378 | 0461 | [0294] | 0175 | 0237 
4 | oos9 | 0070 | 0113 | 0215 | o198 | [0271] | 0395 | 0696 | 0278 | 0204 | 0169 
5 || o111 | [0104] | [0172] | 1265 | 0302 | 0285 | 0251 | 0319 | 0278 | 0261 | [0162] 
6 | 0173 | 0162 | 0174 | 0515 | 0939 | 0229 | 0224 | [0425] | 0281 | 0212 | 0097 
é 
8 
9 
10 
0-0 
0029 | 0172 | 0346 | 0207 | [0447] | 0272 | 0289 | 0287 | 0217 | 0240 | 0155 
[0138] | ooss | 0199 | 0391 | 0476 | 0278 | 0412 | 0255 | 0265 | [0226] | 0124 
0227 | ooss | o1s9 | [0331] | 0288 | 0224 | [0330] | 0528 | 0405 | 0239 | «..... 
0104 | 0092 | 0139 | 0197 | 0482 | o302 | 0442 | 0427 | [0252] | O182 | «+... 
11 01s7 | 0142 | o169 | 0289 | 0275 | [0295] | 0281 | 0311 | 0213°| 0222 | 0102 
12 || 0079 | [0132] | [0166] | 0388 | 0256 | 0417 | 0337 | 0294 | 0231 | 0189 | [0142] 
13 oo62 | 0182 | 0242 | 0292 | 0170 | 0361 | 0330 | [0289] | 0182 | 0149 | 0213 
14 || 0120 | 0144 | 0124 | 0340 | [0281] | 0188 | 0290 | 0285 | 0144 | 0277 | 0153 
15 || [0097] | 0146 | 0136 | 0362 | 0366 | 0307 | 0231 | 0222 | 0132 | [0274] | 0103 
16 || 0099 | 0149 | 0219 | [0317] | 0333 | 0285 | [0275] | 0196 | 0152 | 0567 | 0114 
17 || 0140 | 0090 | 0182 | 0332 | 0287 | 0321 | 0259 | 0239 | [0200] | 0196 | 0109 
is || 0078 | 0139 | 0335 | 0355 | 0274 | [0303] | 0281 | 0213 | 0183 | 0267 | 0119 
19 || oo98 | [0117] | [0217] | 0223 | 0202 | 0348 | 0256 | 0251 | 0370 |- 0182 | [0101] 
20 || 0083 | 0115 | 0143 | 0193 | 0280 | 0294 | 0212 | [0282] | 0220 | 0242 | 0099 
