232 



Abstracts of the Makerstoun Observations, 1843. 



TABLE IX. — Mean Variations of the Horizontal Component of Magnetic Force, after eliminating 

 the Secular Change, with reference to the Moon's Age, Declination, and Distance from the 

 Earth, for 1843. 





Variations 





Variations 



After 



Variations 



After 



Variations 



Before 



Variations 



Before 



Variations 



Moon's 



of Hori- 



Moon's 



of Hori- 



Moon 



ofHori- 



Moon 



of Hori- 



and 



of Hori- 



and 



of Hori- 



Age. 



zontal 



Age. 



zontal 



farthest 



zontal 



farthest 



zontal 



after 



zontal 



after 



zontal 





Component. 





Component. 



North. 



Component. 



North. 



Component. 



Perigee. 



Component. 



Apogee. 



Component. 



Day. 



0-000 



Dav. 



0000 



Dav. 



0-000 



Day. 



0-000 



Day. 



0-000 



Day. 



0-000 



15 



000 







288 







263 



14 



224 



7 



328 



7 



145 



16 



199 



1 



213 



1 



211 



15 



182 



6 



256 



6 



061 



17 



117 



2 



322 



2 



292 



16 



103 



5 



249 



5 



232 



18 



245 



3 



260 



3 



246 



17 



119 



4 



000 



4 



173 



19 



169 



4 



288 



4 



013 



18 



204 



3 



091 



3 



225 



20 



246 



5 



311 



5 



000 



19 



234 



2 



239 



2 



191 



21 



299 



6 



242 



6 



034 



20 



274 



1 



192 



1 



242 



22 



300 



7 



115 



7 



126 



21 



138 



P 



197 



A 



144 



23 



196 



8 



178 



8 



243 



22 



228 



1 



242 



1 



320 



24 



328 



9 



083 



9 



188 



23 



191 



2 



251 



2 



256 



25 



251 



10 



038 



10 



089 



24 



182 



3 



219 



3 



253 



26 



313 



11 



090 



11 



329 



25 



224 



4 



263 



4 



238 



27 



350 



12 



125 



12 



223 



26 



151 



5 



311 



5 



250 



28 



359 



13 



043 



13 



247 



27 



223 



6 



338 



6 



364 



29 



229 



14 



173 











7 



222 



7 



342 



Table IX. was formed from Table VIII. in the manner indicated for the magnetic declination, Table II. 



Variations of the Horizontal Component op Magnetic Force, with reference to the 

 RELATIVE Positions of the Sun, Moon, and Earth, as indicated by the Moon's Age. 



The partial means in the first portion of Table IX. shew distinctly what is more distinctly evident in the 

 following means, namely, the maximum about the period of new moon, and the minimum at the period of full 



moon : 



Means of Groups. 



14 days to 16 days, Full Moon, 0-000124 



17 20 ... 0-000194 



21 24 ... 0-000278 



25 28 ... 0-000318 



29 days to 1 day, New Moon, 



2 5 ... 



6 9 ... 



10 13 ... 



0-000243 

 0-000295 

 000154 

 0-000074 



It should be remarked that there is a secondary minimum shewn in these means at the time of new moon ; 

 this would not have been seen so distinctly, or at all, had larger groups been taken. As this minimum is 

 also shewn, and nearly to the same extent in the mean for 1844,* it may be allowable to conclude, that the 



principal minimum of the horizontal component occurs at the period of full moon ; a secondary, and not very de- 

 cided minimum, at the period of new moon ; and maxima, nearly equal, immediately before and after the period 

 of new moon, 



* Transactions of the Royal Society of Edinburgh, Vol. XVI., Plate IV. 



I 



