SCIENCE-GOS STP. 201 
RADIOGRAPHY. 
By JAMES Quick. 
(Continued from page 169.) 
Conract BREAKERS. 
INCE the advent of Réntgen Kay work, consider- 
able attention has been paid to the form of the 
contact breaker forthe coil, the results obtained amply 
justifying such investigation. As X-Ray work 
proceeded and the size of induction coils was 
The two chief forms now being used in the larger 
X-Ray work are the mercury break and the recently 
introduced electrolytic break. In most mercury 
breaks contact is made and broken by means of a 
vertical metal rod, moving above and below the 
Surface of some mercury contained in a vessel. An 
example of this kind is seen in fig. 7. 
The rod C is actuated by an electromotor 
and is connected to it bya reciprocating 
motion to obtain its vertical oscillations. 
The motor may be wound so as to be 
driven by the current supplied to the 
primary of \thé induction coil, in which 
case it is connected in the same circuit, 
or by a separate battery. The latter is 
perhaps to be preferred, as the speed of 
the motor may more e: 
ly be varied by 
altering the resistance in circuit, and this 
without affecting the current through the 
primary. In fig. 7, B is the motor, K, K, 
the terminals of the same, K., K, the two 
break terminals, one connected to the 
oscillating rod C, and the other to the 
mercury vessel D, while A is a cam arrange- 
Fic. 7, Moron Merccury INTeRRupTor.(") 
continually being increased, it was found that the 
original spring form of break, as was shown upon the 
coil in fig. 4 (av/e, 
p. 167), became 
unsatisfactory. 
The platinumcon- 
lacts wear irregu- 
larly, especially 
when heavy cur- 
rents are sent 
through the coil. 
This entails con- 
stantly filing up 
the contact sur- 
faces and also 
adjustment of the 
break. The noise 
made bythe spring 
also irritates the 
patient. 
(*‘) IT am in- 
debted to the 
kindness of {: 
Messrs. Isenthal 
Potzler for the 
loan of figs. 7 
and § Fo, , Levy's 
H 
ment for varying the height of the surface 
of the mercury, and thus altering the relative 
duration of the make and break. Great 
care must be taken in this form of break that 
the oscillating rod works quite vertically, otherwise 
Mercury Jet INrerrupror.() 
> 
P) 
