1877.] 



Range of Magnetic Declination. 



103 



A. Annual Variation of Ddclination-range. 

 2. The following Table exhibits mean monthly results of the declina- 

 tion-range corresponding to 48 points in the year. It will afterwards be 

 seen (art. 7) that the declination-range depends amongst other things on 

 the relative position of the sun and moon, and hence to eliminate this 

 inequality I have resorted to monthly means. 



Table I. — Containing Monthly Means (48 to the year) of the Diurnal 

 Declination-ranges, thus : — January (0) gives the Monthly Mean of 

 which the Middle Date is the very commencement of the Tear, 

 January (1) that for one "Week after the commencement, and so on. 



Date. 



xooo— ol. 



— VO. 



1 Q 



IOOO— a. 



1870 3 



Mean. 



Jan. 



(0) 



•325 



•320 



•249 



'352 



•312 





(1) 



•334 



•329 



•265 



•367 



•323 





( 2 ) 



•344 



•348 



•279 



•389 



•340 





(3) 



•356 



•363 



•313 



•414 



•362 



Feb. 



(0) 



•389 



•369 



•347 



•435 



•385 





(!) 



•414 



•371 



•359 



•458 



•401 





(2) 



•438 



•379 



•378 



•476 



•418 





(3) 



•479 



•389 



•388 



•496 



•438 



Mar. 



(0) 



•512 



•418 



•395 



•545 



•467 





(!) 



*554 



•465 



•425 



•589 



•508 





(2) 



•593 



•504 



•463 



•634 



•548 





(3) 



•635 



•538 



•499 



•675 



•587 



April 



(0) 



•664 



•554 



•537 



•704 



•615 





(!) 



•689 



•552 



•556 



•731 



•632 





(2) 



•697 



•547 



•555 



•755 



•639 





(3) 



•664 



•535 



•545 



•738 



•620 



May 



(0) 



•641 



•526 



•516 



•713 



•599 



">•> 



(1) 



•605 



•528 



•504 



•688 



•581 



55 



(2) 



•600 



•532 



•508 



•652 



•573 



55 



(3) 



•619 



•549 



•516 



•657 



•586 



June 



(0) 



•626 



•568 



•529 



•663 



•596 



55 



(1) 



•637 



•574 



•538 



•669 



•605 



55 



(2) 



•633 



•582 



•541 



•685 



•610 



55 



(3) 



•614 



•581 



•539 



•683 



•604 



July 



(0) 



•613 



•566 



•533 



•692 



•601 



55 



(1) 



•606 



•558 



•533 



•692 



•597 



55 



(2) 



•611 



•547 



•526 



•678 



•591 



55 



(3) 



•612 



•537 



•528 



•692 



•593 



Aug. 



(0) 



•611 



•546 



•538 



•681 



•594 



55 



(1) 



•623 



•551 



•544 



•684 



•601 



55 



(2) 



•635 



•558 



•550 



•700 



•611 





w 



•631 



•562 



•544 



•686 



•606 



Sept. 



(0) 



•623 



•547 



•534 



•671 



•594 



