aves, but we have already been able to devise
physical Receivers, of wonderful sensitiveness, for them and other
waves of the same nature, such as those of Radiant heat. In the case
of Radiant heat, the Bolometer invented by Professor Langley has been
able to receive and record a change of temperature of the one
millionth of a degree Centigrade, and can easily make visible the heat
of a candle at a distance of one and a half miles. In wireless
telegraphy also the Receiver, perfected by Marconi, is affected by
rills, made by a splash of electric discharge, over 3000 miles away.
If our eyes were sensitive to these frequencies, both of which are
composed, as is also light, of electro-magnetic rills, we could see
anything that was happening anywhere in the world, for they go through
matter as though it did not exist, as light passes through glass;
indeed, if our region of Sight waves was only put an octave lower we
could not use glass in our windows, it would be too opaque, we should
be obliged to have our windows made of thin slabs of carbon or other
substances permeable to Radiant heat waves. Science indeed steadily
points to electricity and magnetism being a form of motion, and it may
be that in these invisible rays we may some day discover the nature
of those mysterious forces; and, even far beyond those, as suggested
in View Four, we may in the not far distant future be able to
appreciate Physical Life itself as a mode of frequency.

We want, as it were, a special "Time Microscope," which I have already
referred to, to examine these vibrations, and a method similar to that
already mentioned in "Space," under Celestial Photography, by which we
may traverse and examine hundreds or thousands of octaves by each
second of exposure; for, although the path extends to infinity, we
have already arrived at the utmost limits of our finite senses, and
find that after all we can only appreciate fifty-one octaves, a few
inches only, as it were, along the line of Infinite extent, reaching
from the finite up to the Reality; and even so it must be borne in
mind that we have only travelled in one direction, whereas the path we
have taken extends in the opposite direction also to infinity. We
started with sixteen vibrations in a second, as the lowest number of
beats we human beings can appreciate as a musical sound; let us now
descend by octaves. The octave below is eight vibrations in a second,
and there are probably many animals that c