620 HR. k. W. RtiCKER AND DR. T. E. THORPE ON A MAGNETIC 
the latter place. The naagiiitude of the Horizontal Disturbing Force, at Alfoid, is 
only 0-00017 C.G S. unit, and its direction may therefore be disregarded. If the 
line which joins Belhelvie (3) to Inverurie be prolonged it passes close to Cabrach. 
The Horizontal Disturbing Force at this place is not directed to the neighbouring 
Elo-in rido-e line, but southward, as thoush the North Aberdeenshire magnetic ridge 
passed close to it. This view is strongly supported by the fact that the v ertical 
Disturbing Force at Cabrach is a maximum relatively to the two nearest stations on 
the same valley line. The values of the \7ertical Disturbances at the three stations 
(expressed in O'OOOl metric unit) are Huntly, — 147; Cabrach, 17; Cock 
Bi-idcre — 146. On the other hand, at the nearest station on the Elgin ridge line, 
viz., Dufftown, the Vertical Disturbing force is a high 'iiiciximu'm, being -|“ 
against + 34 at Buckie, and -f- 15 at Ballindalloch. 
We cannot but regard this district as presenting a very satisfactory example of the 
remarkable agreement between the minor indications afforded by our obseivations. 
The direction of the Horizontal Disturbing Force is abnormal at one station only 
(Alford), and there its magnitude is so small that the discrepancy is of no importance. 
The occurrence of a “ col,’' at the point where the other ev^idence shows that a iidge 
line and valley line intersect, and of a peak at the point where the two iidge lines 
meet, are also remarkable confirmations of the view tnat, although the Noith 
Aberdeenshire and Elgin Districts are separated by a well-defined valley line which 
never passes over a region of great Vertical Disturbance, they are nevertheless in 
magnetic connection. 
The valley line which separates the North and South Aberdeenshire Distiicts is 
probably a continuation of that which runs from Forres towards Ballindalloch. Of 
the two districts the southern appears to be the less important. The Vertical 
Disturbing Force, though a local maximum at Cairn O’Mount, is small (— 2) at that 
place, but the Horizontal Disturbing Forces there, and at the three nearest stations, 
prove that a centre of attraction is not far distant. I he chain of stations lun along 
the coast southwards from Aberdeen gave somewhat doubtful results. There is a 
well-marked maximum of Vertical Force at Station (6) (the second southvaids fiom 
Aberdeen), but there is also a less important maximum at Stonehaven itself, and the 
Horizontal Disturbing Force at the intermediate station (7) points to this. Putting 
(7) on one side, the facts fit best with the hypothesis of a weak locus of attraction 
running a little north of (6), and of Cairn O’Mount, though the result at (7), and the 
general aspect of the arrows which represent the Horizontal Disturbing Forces, make 
it possible that in this region there are a number of unimportant and, more or less, 
isolated centres of attraction. 
District 6. — Crieff. 
This is a much more important district than the preceding, but it also shows 
signs of the comparative complication, which is one of the characteristics of a minoi 
