466 Transactions.— Miscellaneous. 
The rotation of the ethereal corpuscules within the surface of the earth 
would be so considerably reduced that the force of gravity would be 
lessened. The corpuscules, whose rotation had been reduced, would react 
on those at and probably immediately above the surface of the earth. 
. According therefore to the nature of the layer of the earth's crust, whether 
of greater or less density, so would vary the force of gravity very near the 
earth's surface, Where these layers were very dense there the force of 
gravity would be les. In a very hard rocky country the force of gravity 
would therefore be less than at the surface of the ocean. If a mountain is 
more dense than the surrounding country the force of gravity on the top 
of the mountain should be less than on the surronnding plains. Until the 
nature of an accelerating force is understood, the principles here sketched 
cannot be extended with any satisfaction beyond the surface of the earth. 
The following bears directly upon what has just been said :— 
* An immense number of pendulum observations are now being made 
at the astronomical stations of geodesieal surveys in Germany, Russia, and 
India, which, when fully published, will throw light more perhaps on the 
local variations of gravity than on the figure of earth. The observations 
made at the various stations of the Indian meridian are bringing to light a 
physical fact of the very highest importance and interest, namely, that the 
density of the strata of the earth’s crust under and in the vicinity of the 
Himalayan Mountains is less than that under the plains to the south, the 
deficiency increasing as the stations of observation approach the Himalayas, 
and being a maximum when they are situated on the range itself. This 
accounts for the non-appearance of the large deflections which the Hima- 
layas, according to Archdeacon Pratt’s calculations, ought to produce. The 
Indian pendulum observations also throw some light on the relative varia- 
tions of gravity at continental, coast, and island stations, showing that, 
without a single exception, gravity at the coast stations is greater than at the 
corresponding continental stations, and greater at island stations than at 
coast stations.” The inference, that because the force of gravity in any 
locality is less, the density of the earth at that place is less, is one usually 
made, but it is more credible that mountains are denser than the plains 
which are made up of detritus from those mountains than that the plains 
are denser than the mountains."* 
Prof. Darwin made experiments during last year, in which he dis- 
covered variations in the force of gravity. He has embodied the results of 
~ his investigation in a paper which was published in the November number 
of “ Nature” last year. His investigations showed that the force of gravity 
varied at the very same place, that there was on one or two days a diurnal 
variation in the force of gravity. 
* See Article “ Earth” (figure of) in the Encyclopedia Britannica, by R. E. Clark. 
