1X11 



Genekal Results of the Makeestoun Observations. 



Table 58. — Diurnal Variations of Magnetic Dip for diflferent periods, deduced from Table 57- 

















Six Months. 





Mak. 

 Mean 

 Time. 



Dec. 

 Jan. 

 Feb. 



March. 

 April. 



May. 

 June. 



July. 

 Aug. 



Sept. 

 Oct. 

 Nov. 



Sept. 

 to 



March 

 to 



Twelve 



Months. 

















Feb. 



Aug. 



— 7 



h. 



m. 



/ 



- 



/ 



. 



/ 



' 



/ 



12 



12 



+ 0-163 



-0-346 



-0-176 



-0-424 



-0-202 



-0-019 



-0-315 



-0-168 



13 



12 



+ 0-192 



-0 



031 



-0-069 



-0-186 



- 0-288 



-0-048 



-0-095 



-0072 



14 



12 



+ 0-347 



+ 



331 



+ 0-060 



-0-042 



-0-157 i 



+ 0-095 



+ 0116 



+ 0105 



15 



12 



+ 0-075 



-0 



042 



+ 0-168 



+ 0-032 



-0-382 



-0-153 



+ 0-053 



-0-051 



16 



12 



-0-140 



-0 



048 



+ 0-331 



+ 0-179 



-0-443 



-0-291 



+ 0-154 



-0069 



17 



12 



-0-370 



-0 



158 



+ 0-447 



+ 0-454 



-0-448 



-0-409 



+ 0-248 



-0-081 



18 



12 



-0-423 



-0 



184 



+ 0-731 



+ 0-664 



-0-270 



-0-346 



+ 0-404 



+ 0-029 



19 



12 



-0-360 



+ 



ISO 



+ 1-148 



+ 1-190 



+ 0-181 



-0089 



+ 0-839 



+ 0-375 



20 



12 



-0-146 



+ 



928 



+ 1-721 



+ 1-856 



+ 0-768 



+ 0-311 



+ 1-502 



+ 0-906 



21 



12 



+ 0-163 



+ 1 



463 



+ 2012 



+ 2-261 



+ 1-374 



+ 0-768 



+ 1-912 



+ 1-340 



22 



12 



+ 0-399 



+ 1 



679 



+ 2023 



+ 2-210 



+ 1-511 



+ 0-955 



+ 1-971 



+ 1-463 



23 



12 



+ 0-374 



+ 1 



485 



+ 1-483 



+ 1-589 



+ 1-191 



+ 0-782 



+ 1-519 



+ 1151 







12 



+ 0-241 



4-0 



916 



+ 0-718 



+ 0-833 



+ 0-655 



+ 0-448 



+ 0-822 



+ 0-635 



1 



12 



-0036 



+ 



183 



-0055 



+ 0-036 



+ 0-069 



+ 0-016 



+ 0-055 



+ 0-035 



2 



12 



-0-181 



-0 



289 



-0-596 



-0-541 



-0-177 



-0-179 



-0-475 



-0-328 



3 



12 



-0-172 



-0 



632 



-0-901 



-1-089 



-0-377 



-0-274 



-0-874 



-0-574 



4 



12 



-0-159 



-0 



799 



-1-383 



-1-270 



-0-379 



-0-269 



-1-151 



-0-710 



5 



12 



-0-092 



-0 



913 



-1-618 



- 1-603 



-0-502 



-0-297 



-1-378 



-0-838 



6 



12 



-0-125 



-0 



837 



-1-660 



-1-597 



-0-497 



-0-311 



-1-365 



- 0-838 



7 



12 



-0-071 



-0 



711 



-1-640 



-1-409 



-0-412 



-0-241 



-1-253 



-0-748 



8 



12 



- 0-033 



-0 



611 



-1158 



-1120 



-0-336 



-0-184 



-0-963 



-0-574 



9 



12 



+ 0-043 



-0 



469 



-0-739 



- 0-797 



-0-308 



-0-132 



-0-668 



-0-401 



10 



12 



+ 0-198 



-0 



552 



-0-565 



-0-671 



-0-291 



-0-046 



-0-596 



-0-321 



11 



12 



+ 0-108 



-0-554 



-0-275 



-0-557 



-0-268 



-0-080 



-0-462 



-0-271 



129. The approximate epochs of maxima and minima in apparent time, from Table 58, are : — 



Maximum, 

 Minimum, 

 Maximum, 

 Minimum, 



Dec. Jan. Feb. 



+ 10h 20"i A.M. 



2*^ 50™ P.M. 



2'^ 5™ A.M. 



— &^ 5"^ A.M. 



March, April. 

 + IC^ 15"^ A.M. 

 — 5*' 0™ P.M. 

 2^ 10™ A.M. 



5h 45m ^ jy._ 



May, June, 

 9h 50™ A.M. 

 G"^ 20m P.M. 



July, Aug. 

 Qh 35" A.M. 



b^ 30™ P.M. 



Sept. Oct. Nov. 

 + IQli 0"! A.M. 

 — 5'^ 35ra P.M. 

 l*" 55™ A.M. 



4^ 55"" A.M. 



The principal maximum, near IC* a.m., occurs earliest in July and August, and latest in December to Feb- 

 ruary : the afternoon minimum occurs earliest in the three winter months, and latest in May and June : the 

 other maximum and minimum occur earliest in the months September to November. (See the Continuous 

 Curves, Plate IV., where it is to be remembered that the apparent minima of the curves are the maxima of dip.) 

 The following Table contains the diurnal variations for the days selected as nearly free from intermittent dis- 

 turbance. 



130. The approximate epochs of maxima and minima in apparent time for the undisturbed diurnal varia- 

 tions, are as follow : — 



Maximum, 

 Minimum, 

 Maximum, 

 Minimum, 



Dec. Jan. Feb. 



+ Kfi" 45m A.M. 



5*^ 25m P.M. 



V^ 35in A.M. 



— Q^ 25m A.M. 



March, April. 

 + 10»' 20m A.M. 

 — 7^ 5™ P.M. 



3^^ 20™ A.M. 



b^ 15™ A.M. 



May, June. 

 9i> 50m A.M. 

 Q^ 30™ P.M. 



July, Aug. 

 Q^ 45m A.M. 

 7*^ 0™ P.M. 



Sept Oct. Nov. 

 + 10'' 15™ A.M. 

 — G'^ 45m P.M. 



X^ 55m A.M. 



5'' 5m A.M. 



In tlie undisturbed, as in the distui'bed variations, tlie principal maximum occurs earliest in July and 

 August, and latest in December to February ; but, unlike the disturbed variations, the afternoon minimum 

 occurs latest near the equinoxes ; it occurs rather earlier at the winter than at the summer solstice. (See the 

 Dotted Curves, Plate IV.) 



