At least one underground laboratory has already been installed, for Prof. E. B. Babcock of the University of California has such a workroom in the Twin Peaks Tunnel, underneath the mountain that rises above the city of San Francisco. Natural radioactivity in the rocks thereabouts is greater than normal and Prof. Babcock finds that this apparently increases new species among fruit flies.
To dig out laboratory rooms a mile or so down in existing deep mines probably would cost far less than many enterprises already financed by philanthropists. Even to deepen these shafts for several miles would be much less difficult than most people imagine.
Increasing heat, if it is found that heat does increase, would not be difficult to overcome had the engineers sufficient money. Ventilation and transportation to and from the surface, while too costly for the business enterprise of winning metals from very deep mines, probably would present no serious difficulty were facts the chief object instead of profit. The only question to be decided before intending benefactors of science are urged to consider some such project is whether or not the facts likely to be won promise enough value to mankind.
An excellent case can be made out for answering yes. Dr. Shapley mentioned four chief lines of investigation suitable for such deep-mine laboratories: studies of gravity and of the variable length of the day, researches on the various kinds of earthquake waves, experiments on ether drift and tests of the biological effects of cosmic rays and of the rays from radium.
Astronomical theories indicate that the day ought to be growing slightly longer as the earth's rotation decreases a trifle from century to century because of friction from the tides. The actual length of the days seems, however, sometimes to be decreasing a tiny fraction of a second from year to year, as theory says that it should; sometimes to be increasing in a way for which no present theory provides. Observations underneath the earth, with a portion of the planet's crust and gravity overhead, might yield important clues to the cause of this mysterious wrong time kept by the terrestrial clock.
They were almost upon him when he leaped into action.