will come no one will question;
but where is the daring prophet who will hazard a guess as to what
they will be?

THE UNKNOWN RAY AND ENTOGRAPHY.

It is difficult to name the unknown. In the ancient world all the
unknown was included in the idea of God. It remained for the
evangelist to declare that God is a _spirit_--thus separating the
natural forces of the material world from the Supreme Power who is
from eternity.

This century has been the epoch of investigation into the nature of
the imponderable forces. Sound and light and heat have been known as
the principal agents of sensation since the first ages of man-life on
the earth; but their nature has not been well understood until within
the memories of men still living. Electricity was also vaguely
known--but very indistinctly--from ancient times. It has remained for
the scientific investigators of our age to enter into the secret parts
of nature and lay bare to the understanding many of the hitherto
unknown facts relating to the imponderable agents.

The laws of heat, of acoustics, of light, have been clearly arranged
and taught; but they have not been placed beyond the reach of new
interpretation and possibly not beyond the reach of complete
revolution and reconstruction. That which has been accepted as
definitely known with regard to these agents has now to be reviewed,
and possibly to be learned over again from first principles.

As to electricity in its various forms and manifestations, that
sublime and powerful agent began to be better known just before the
middle of the century. Since that time there has been almost constant
progress in the science of this great force, until at the present time
it is handled, controlled and understood in its phenomena almost as
easily as water is poured into a vessel, air compressed under a
piston, or hydrogen made to inflate a balloon.

It has remained, however, for the last half decade of the great
century to come upon and investigate a hitherto unknown force in
nature. Certain it is that the new force exists, that it is
everywhere, that it is a part of the profound agency by which life is
administered, that its control is possible, and that its probable
applications are as wonderful--perhaps more wonderful--than anything
ever hitherto discovered by scientific investigation.

It is not unlikely that since the day, or evening, on which Galileo,
with his little extemporized telescope, out in the garden of the
Quir