220 A new Automatic Gas-Pump. 
ports in the same manner as an ordinary slide-valve, but 
since the travel of this slider 8 (fig. 2) is only one-eighth of 
A communicates with the mechanical pump. 
9 * lower chamber L. 
C ” * the trap T. 
an inch many devices are possible for actuating it; an 
electromagnet appears very suitable. 
Two relays are introduced, one into each circuit, in order 
that the current which operates the control-valve may be 
broken at external mercury cups. 
In the circuit, the completion of which moves the slider 
into the position for allowing air to enter L, the action of 
the relay is retarded, for the purpose of enabling the mercury 
in the Toepler pump to remain in the lower chamber during 
a distinct interval of time before ascending. 
A small hole H bored through the slider-flange ensures 
that the inrush of air into the lower chamber may be checked, 
and the upward movement of the mercury therefore take 
place slowly. The ideal conditions for efficiently working 
the Toepler pump are therefore attained, for the mercury 
rises slowly, sweeping out before it very efficiently the gas 
which fills the upper chamber; on the other hand, it falls 
rapidly (so that no time may be lost) and remains in the 
lower chamber for a fixed period before again ascending. 
Experiment has shown that the apparatus is fairly rapid 
in its action. Careful tests under specific conditions are in 
progress, but not yet sufficiently complete for publication. 
{n a preliminary trial, however, the capacity of the chamber 
U being 160 c.c., 5 lbs. of mercury were raised three times 
per minute, with the result that a Rontgen-ray bulb of 
200 c.c. capacity was exhausted in half-an-hour. The glass 
work is easily removable for cleaning or repairs, and the wood 
supports fitted with adjustable brackets. ‘The height of the 
complete apparatus is 18 inches. 
