ON THE MAGNETIC SURVEY OF SCOTLAND. 



183 



Table XIV. 



Station. 



Ardrossan .. 

 Port Askeg 

 Bridgend . . 

 Toberniorie 

 Glenmorven 

 Balmacarra 

 Kyleakin .. 

 Broadford .. 



Portree 



Stornoway.. 

 Callinish . . 



Cross 



Loch Inver 



Durness 



Thurso 



Lerwick 



Kirkwall .. 



Wick 



Golspie 



Dingwall . . 



Date. 



1858. 

 July 12 

 16 

 19 

 24 

 26 

 28 

 29 

 30 

 30 

 5 



10 



11 



16 



16 



18 



23 



30 



31 



4 



7 



9 



Aug. 



Sept. 



Total force. 



(1) By 



Dr. Lloyd's 



method. 



10-614 

 10-714 

 10-703 

 10-799 

 10-754 

 10-692 

 10-672 

 10-693 

 10-636 

 10-727 

 10-741 

 10-759 

 10-619 

 10-636 

 10-743 

 10-684 

 10-716 

 10-727 

 10-720 

 10-708 

 10-696 



(2) By the 

 method of 

 vibrations. 



10621 

 10-655 

 13-675 

 10-661 

 10-899 

 10-634 

 10-636 

 10-682 

 10-605 

 10-689 

 10-666 

 10-742 

 10-512 

 10-512 

 10-697 

 10-674 

 10-738 

 10-721 

 10-700 

 10-692 

 10-632 



(2)-(l) 



+•007 

 -•059 

 -•028 

 -•138 

 + •145 

 -•058 

 -•036 

 -•011 

 -•031 

 -•038 

 -•075 

 -•017 

 -107 

 -•124 

 -•046 

 -•010 

 + 022 

 -•006 

 -•020 

 -•016 

 -•064 



By this Table we see that the constant which suited the observations taken 

 at Kew in June 1858 does not suit those taken in Scotland a month or two 

 afterwards, for, when applied to them, it makes the resulting force too great. 

 The instrument must therefore have changed its constant between June and 

 July in such a manner, that, had it been observed at Kew in July, it would 

 have given a larger reading than it gave in June. This agrees with what we 

 inferred from the observations of Table XII. taken at Kew with the face of 

 the deflected needle to the east, viz. that a rise in the readings must have 

 taken place at some time between January and November 1858. To con- 

 clude, — in this case at least, the results obtained by Dr. Lloyd's method do not 

 bear comparison in accuracy with those determined by means of the method 

 of vibrations. I have therefore made no use of the former in deducing ge- 

 neral results. 



Division III. — Declination. 



During the first year (1857) the Declination observations were made in 

 the following manner. A collimator magnet was employed, the division on 

 the glass scale of which corresponding to the magnetic axis was first accu- 

 rately determined. Great care was taken that the collimator scale should not 

 be touched, or its position with reference to the magnet in any way altered*. 



* There is every reason to believe that this care was successful in securing a fixed position 

 of the magnetic axis with reference to the scale. From a determination at Kew before the 

 commencement of the first year's survey, 49-7 on the scale denoted the magnetic axis. Be- 



