EDITORIAL 281 
the atoms, as well as reduction of interatomic space, is now definitely 
recognized as a possibility and even a probability by Richards 
and others. The diastrophism of the atom is now to be a theme 
of inquiry, as well as the diastrophism of the earth. 
Most of the old computations of geophysical application were 
based on assumed incompressibility, but mathematicians and geo- 
physicists are already reworking their computations on the basis 
of compressibility. This finds expression in such recent titles as 
“General Theory of a Gravitative Compressible Planet,” ‘‘ Effect 
of Compressibility on Earth Tides,” “Vibrations of a Gravitative 
Compressible Planet.’ 
It tallies well with the new ideas of compressibility that there 
should be coming to light new forms of familiar substances as these 
are forced to pass through changes of physical condition, particu- 
larly changes of pressure. Bridgman, in a group of notable papers,’ 
recognizes five solid forms of water, and hints that there may be 
more. In this series of contributions there seems to us to be ground 
for the inference that molecular rearrangement may not improbably 
be a common rather than an exceptional property when conditions 
of pressure notably change. It is perhaps not too much to surmise 
that a successon of rearrangements of molecules may take place 
where there is a succession of marked changes of pressure, such, 
for instance, as would arise with increasing depth in the course of 
the earth’s growth, assuming that it grew by solid accretions. 
Some few such rearrangements falling within the limits of the 
solid state are well known, but it now seems not unlikely that 
there may be a series of such rearrangements following the analogy 
of the five solid states of water treated by Bridgman. 
t Theodore W. Richards, Year Book No. rr, Carnegie Inst. of Washington, 1912, 
pa 255- 
2A. E. H. Love, Some Problems of Geodynamics, University Press, Cambridge, 
England, tort. 
3P. L. Bridgman, Contributions from the Jefferson Physical Laboratory of Harvard 
University, IX (1911), Nos. 4, 5, and 6; ‘‘The Measurement of Hydrostatic Pres- 
sures up to 20,000 Kilograms per Square Centimeter,’ Proc. Am. Acad., XLVI, 
No. 11; ‘Mercury, Liquid and Solid, under Pressure,” Proc. Am. Acad., XLVI, 
No. 12; ‘The Collapse of Thick Cylinders under High Hydrostatic Pressure,” Phys. 
Review, XXXIV, No. 1; ‘‘ Water, in the Liquid and Five Solid Forms, under Pressure,”’ 
Proc. Am. Acad., XLVII, No. 13. 
