A Mount Holyoke College profes
sor, Elizabeth R. Laird, ,is finding
some success at one end ojf the gap
and investigations at the 'other end
were completed some time ago. At
the one end are the ultra-violet rays
and at the other are Entladungestrah
len and soft X-rays. It is with this
latter class that Miss Laird has had
considerable success.
The first of the waves of radiation
to be studied were those of visible
light. The spectrum received the at
tention of the physicist, who found
tr.at the interval from the red to the
violet was, in the language of the
physics of sound, less than an octave,
the violet rays having less than twice
the frequency of the red ones. Natu
rally the question arose as to exactly
what was outside this brief space of
waves capable of affecting the sense
of vision. '
And so outside were found infra
red waves of heat and above these,
beyond another gap, were found
Hertzian waves used in wireless,
while at the lower end of the spec
trum appeared the celebrated ultra
violet ray. Then came the long gap,
the missing link for which the physi
cist is searching, and after that the
Entladungsstrahlen, joined to the X
rays. Last on the scale are the gam-may-rays,
probably in the neighbor
hood of two five-bllllonths of an. inch
in length. From the waves of wire
less which are often ten miles long
to the minute waves of the gamma
ray, the visible and the invisible spec
trum is continuous save for the two
narrowing gaps on opposite sides of
the visible section.
