236 The Philippine Journal of Science 1921 
We have great rainfall over most of Malaysia to-day. There 
is every reason to suppose that this has been the case throughout 
most of the Tertiary period, which is the age of the tropical 
Malaysian coal. These great deluging downpours of rain mean 
coarse sedimentation. and frequent interruptions to the quiet 
accumulation of vegetal matter from which we are to hope for 
a future coal deposit. We do find that the character of the 
underlying and overlying beds in the neighborhood of these 
uncertain coal beds is very variable; coarse and fine strata alter- 
nate with, in many places, no great thickness to any one stra- 
tum. So the advice to the engineer or geologist who is sent 
out to examine a coal deposit in any part of the Tropics is this: 
Examine carefully the nature of the inclosing strata, the charac- 
ter of the grains, their size and arrangement, and take nothing 
for granted; put down test pits or drill holes fairly closely 
spaced and, better still, drive on the coal. The reader who 
would care for more detailed discussion of this topic will find 
an admirable paper on the subject by Pratt.’ 
Geodesy.—Over fifty years ago there appeared in the Trans- 
actions of the Royal Society * several articles by the Bishop of 
Calcutta, a mathematician and physicist of no mean repute, 
relating to the perplexities then confronting the surveyors in 
control of the great Trigonometric Survey of India. This, one 
of the greatest of surveys, has recently been completed. The 
problem that confronted them was how to account and allow 
for a very noticeable and very important discrepancy between 
the trigonometrically located stations and those ascertained by 
astronomical determinations. 
It was expected that the great mass of the Himalayas would 
deflect the plumb bob toward them, but another factor entered 
into the problem which at first was not understood, namely, 
density. There was for some reason a deflection of less amount 
of the negative sign which could not be accounted for; it was 
finally accounted for by assuming a deficiency of gravity beneath 
the mountain mass and a greater gravity beneath the sunken 
area to the south. The whole question is intimately bound up 
with the theory of isostasy, which is too complex a subject for 
review in this paper. 
In 1906 Hayford ® wrote a paper, in which the whole question 
is reviewed and the theory of isostasy clearly substantiated. 
* Pratt, W. E., Philip. Journ. Sci. § A 10 (1915) 289. 
* Phil. Trans. Roy. Soc. London (1853). 
* Hayford, John T., Proc. Washington Acad. Sci. 8 (May, 1906) 25—40. 
