104 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. 



In searching for an explanation of these peculiarities it is natural 

 to turn in the first place to a modification of the hypothesis of com- 

 pensation and a reference to table 8 shows that no help is to be 

 got from supposing an alteration in the depth to which uniform 

 compensation extends, for an increase in depth leads to a larger 

 northerly residual at stations near the edge of the hills than at 

 those further in, and a lesser depth merely gives a nearly uniform 

 southerly residual. Table 'J shows that the adoption of an hypo- 

 thesis of support by flotation gives some help, for it would give a 

 northerly residual, as compared with calculations from Mr. Hayford's 

 tables of some 3" greater than at a station situated outside the 

 range, but as regards stations within the range, situated as are 

 Lambatach and Mussooree, it would merely give a nearly uniform resi- 

 dual of about — 3". It is obvious, therefore, that the explanation 

 must lie in a departure from a locally complete compensation, and 

 table No. 10 shows that, without going beyond the bounds of an 

 easily accepted departure from the conditions assumed in the other 

 tables, we can account for all the difference which is actually found 

 between stations some thirty or forty miles apart. A supposition of 

 this sort also allows of the passage from northerly to southerly 

 residuals, which is suggested by the figures in table No. 29 ; but 

 it is useless to pursue this matter further till the gravity observations 

 have been dealt with. 



Meanwhile it can be said that the measurements of the deflection 

 of the plumb-line show that, northwards of about 30 miles from the 

 edge of the Himalayas proper, the hills are superelevated, or, other- 

 wise, that the compensation is in defect ; but the amount of this 

 departure from normal conditions depends largely on the manner 

 in which it is distributed between the surface topography and the 

 compensation, and this will be considered further on. 



Besides the latitude stations, which have been considered, there 

 are three others, separated by a long interval and situated in 

 the north-western extremity of the range. Two of these are in 

 the interior of the hills, on the southern edge of the valley of Kashmir, 

 and will be more conveniently considered further on, the third is 

 the station of Murree, situated near the edge of the Himalayas 

 proper, but separated from the alluvium of the Punjab by some 

 80 miles of low hills. At this station a northerly deflection of 16" 

 was observed, of which 10" are accounted for by the effect of the 



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