14 Rey. O. Fisher on Deflexions — 
fortuitously occur is exceedingly improbable. If there were 
something like an attraction in phase between systems with 
the same values of 7, some sorting effect might be expected 
to occur, but scarcely otherwise; and thus, as it appears to 
me, instead of requiring an assumption to make 7 decrease, 
we should require an assumption to keep it from decreasing. 

Ill. On Deflewions of the Plumb-line in India. By Rey. 
O. Kiser, W.A., #.G.S., Hon. Fellow of Jesus College, 
Cambridge, and of King’s College, London”. 
1 ae in 1902 I received, kindly sent to me by the 
4 author at the suggestion of my friend Mr. Oldham, 
Superintendent of the Geological Survey of India, a Report 
on the attraction of the Himalaya Mountains upon the 
plumb-line in India t. The observed phenomena led the 
Surveyors to suspect the existence of what they term a 
hidden chain of excessive density, traversing India from 
Balasore near the mouth of the Hooghly to Jodhpur in 
Rajputana, and underlying Manata and Bhopal. The position 
of this supposed chain is given in chart No. 6 of the Report. 
It appears however that, if such a chain exists as to cause 
deflexion of the plumb-line towards it, its presence ought 
likewise to be betrayed by its influence upon the pen- 
dulum; because gravity ought to be locally increased 
above it. 
Now, in the ‘Account of the Great Trigonometrical Survey 
of India’ t+, we learn that there is no escape from the con- 
clusion that there is a more or less marked negative variation 
of gravity over the whole of the Indian continent. These 
variations are tabulated in my ‘ Physics of the Harth’s Crust ’§, 
and it appears that there is a slight increase of density at 
Kalianpur in latitude 24° 7’, which is in the position of the 
supposed hidden chain, but at the same time there is another 
nearly of the same amount at Usira in latitude 26° 57’, so 
that if the one affect the plumb-line the other ought to do 
so in the same manner. ‘The deficiency in the vibration 
number calculated for the sea-level, which is due to diminished 
* Communicated by the Author. 
+ By Major S. G. Burrard, R.E., Superintendent of the Trigono- 
metrical Surveys of India. Dehra Dun, 1901. 
t Calcutta, 1879. By General Walker. 
§ 2nd ed. p. 208. 
