242 SCIENCE. 
action may be at its extreme when barium 
platinocyanide, excited by Rontgen rays, so 
lowers the pitch as to produce rays within 
the visible spectrum, for this compound 
gives very little or no Rontgen-ray diffu- 
sion. Are there substances which under 
Rontgen rays fluoresce with invisible rays 
of the order of the ultraviolet of the spec- 
trum? If, as is the case with solid par- 
affine, the irradiated substance gives rise to 
considerable diffusion it can, as Ihave noted, 
produce a secondary diffusion in other 
masses of the same substance, or of other 
substances, as indicated by feeble fluores- 
cence of the sensitive barium salt, thor- 
oughly screened from the direct source of 
rays and from the first or primary diffusion. 
It is probable that Tertiary diffusion could 
be found if we possessed a far more power- 
ful or continuous source of the rays for ex- 
citing the initial diffusion. The ray emis- 
sion, even in the most powerfully excited 
tube, is probably so intermittent that the ac- 
tive period is but a fraction of the total time. 
It may easily be that the limit of intensity 
of Rontgen-ray emission has not yet been 
reached, especially when artificially cooled 
anti-cathode plates are available. 
There is much room for experimental 
work in this fascinating field. We need 
for it the means for the production either 
of a continuous electric discharge at from 
60,000 to 100,000 volts or a high-frequency 
apparatus capable of giving an unbroken 
wave train; that is, a succession of high 
period waves of current without breaks or 
intermissions. 
The ordinary high-frequency apparatus 
for obtaining discharges of high potential 
from alternating currents gives only a 
rapid succession of discharges each con- 
sisting of a few rapidly dampened oscilla- 
tions. These discharges occupy but a small 
fraction of the total time. This is very 
different from a continuous sustained wave 
train, with the successive waves of equal 
[N. 8. Vou. X. No. 243. 
amplitude following each other without 
break. Such sustained waves will, doubt- 
less, be of use in research, especially in 
vacuum-tube work, and they would, of 
course, convey much more energy than the 
usual brokon or interrupted discharge 
known as a high-frequency discharge. 
Some six or seven years ago I endeay- 
ored, while working upon the subject of 
high frequency, to fill the gap. The result 
was an apparatus which, with its modifica- 
tions, deserves more study and experiment 
than I have been able to give to it. A 
brief description may not be out of. place. 
A large inductance coil with a heavy iron 
wire bundle for a core, a coil of relatively 
few turns with no iron core, and a con- 
denser of variable capacity, were connected 
in series across the mains of a 500-volt 
electric circuit. The smaller coreless coil 
and the condenser were arranged to be 
shunted by an adjustable spark gap with 
polished ball terminals. By simply closing 
for a moment the spark gap so as to form a 
low resistance shunt around the condenser 
and the small coil, and afterward slowly 
separating the balls, the local circuit of the 
condenser, small coreless coil and shunting 
gap become the seat of sustained oscilla- 
tions, the frequency of which depends upon 
the relation of inductance and capacity in 
the local circuit. The energy supplied is 
that of a continuous current through the 
large inductance coil with the heavy core. 
The action of the apparatus is easily com- 
prehended by a little study. The oscilla- 
ting current in the local circuit may be 
made to induce much higher potentials in 
a secondary circuit inductively related 
thereto. In this case the turns of the sec- 
ondary in relation to the primary are, as 
usual, such as to step-up the potential. In 
other words the potential developed in the 
secondary is determined by the transform- 
ing ratio. 
We thus havea high-frequency apparatus 
