ON THE MAGNETIC SURVEY OF SCOTLAND. 



179 



Making this our unit, we obtain the following values of / and r for the 

 central station,/= 1-0309 ; r = -0000933. 



We may now compare together the two surveys, with respect to k and r, 

 in the following Table : — 



Table X. 



From this Table, it would seem that the angle u has changed very little 

 during the twenty-one years between the two surveys ; while, on the other 

 hand, r, or the change of force in the normal direction for one geographical 

 mile, appears to have diminished considerably. 



In the following Table the observed values of total force are compared 

 with those calculated for the various stations : — 



Table XI. 



Station. 



Observed 

 Total Force. 



Calculated 

 Total Force. 



Observed 

 minus cal- 

 culated. 



Makerstoun .... 



Edinburgh 



Gretna 



Dumfries 



Newton Stewart 



Stranraer 



Ayr... , 



Lamlash 



Helensburgh .... 

 Lochgoilhead.... 



Ardrishaig 



Oban 



Corpach 



Fort Augustus . 



Inverness 



Banff 



Peterhead 



Aberdeen 



Kintore 



Alford 



Braemar 



Pitlochry 



Dalwhinnie .... 



Larbert 



Ardrossan 



Port Askeg .... 



Bridgend 



Tobermorie .... 

 Glenraorven .... 



10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10' 

 10' 

 10' 

 10' 

 10- 

 10- 

 10' 

 10- 

 10- 

 10- 

 10- 

 10- 

 10 



546 



558 

 505 

 519 

 523 

 519 

 548 

 •595 

 538 

 •531 

 •575 

 •560 

 ■702 

 ■647 

 ■667 

 596 

 ■582 

 543 

 ■550 

 599 

 587 

 535 

 598 

 552 

 621 

 655 

 675 

 661 

 899 



10-517 

 10548 

 10501 

 10515 

 10-525 

 10-535 

 10-553 

 10-564 

 10-581 

 10-590 

 10-594 

 10-614 

 10-626 

 10-631 

 10-636 

 10-614 

 10-594 

 10-582 

 10-592 

 10-598 

 10-601 

 10-592 

 10-614 

 10-563 

 10-564 

 10-601 

 10-600 

 10-634 

 10-632 



+•029 

 +•010 

 +•004 

 +•004 

 -•002 

 -•016 

 -•005 

 +•031 

 -•043 

 -•059 

 -•019 

 -•054 

 +•076 

 +•016 

 +•031 

 -•018 

 -•012 

 -•039 

 -•042 

 +•001 

 -•014 

 -•057 

 -•016 

 -•011 

 + •057 

 +•054 

 +•075 

 +•027 

 +•267 



