DAY: GEOPHYSICAL RESEARCH 257 
proverbial mustard-seed or a walnut, the scientific laboratory 
cannot properly afford the time necessary to produce the large 
crystals which nature offers so abundantly. Furthermore, the 
crystals of nature often owe their brilliant coloring to slight 
admixtures of impurity, which, to the scientific laboratory, spell 
failure and are avoided with the utmost care. Most of the mineral 
crystals, when reproduced in the laboratory, are quite colorless. 
And so, altho the question is often raised whether we are not really 
engaged in the artificial production of gems, and altho the seduc- 
tive character of such an investigation would no doubt appeal 
to many, it must be admitted that the geological laboratory is 
not and probably will never become the serious competitor of 
nature in those directions in which nature has produced her most 
brilliant effects. 
In what has preceded, I have laid emphasis upon the value of 
experimental measurements in the systematic development of a 
more exact science of the earth. It is a fair question, and one 
which is very often raised, whether all this investigation has a 
utilitarian side, whether the knowledge obtained in this way and 
with such difficulty, will help to solve any of the problems arising 
in the exploitation of our mineral resources or assist in our indus- 
trial development. It is neither wise nor expedient, in entering 
upon a new field of research, to expatiate long upon its practical 
utility. Its principles must first be established, after which there 
is no lack of ingenuity in finding profitable application of them. 
The development of thermoelectric apparatus for the accurate 
measurement of high temperatures was begun and has been per- 
fected in the interest of geophysical research, and it has already 
found such extended application among the technical industries 
as to demand the manufacture and calibration of thousands of 
such high temperature thermometers every year. The temper- 
ing and impregnation of steel are no longer dependent upon the 
more or less trained eye of the workman, but are done at measured 
temperatures and under known conditions which guarantee the 
uniformity of the product and admit of adaptation to particular 
purposes, like high speed tools or armor plate. This has the 
incidental but far-reaching industrial consequence that workmen 
