o 
38. ELECTRODYNAMIC CURRENT INTERRUPTER of adjustable 
pitch. Connected with transformer and condenser. The 
secondary coil of the transformer is connected with the coils 
of exhibit 38 a. 
38 a. CURRENT CHANGER OF ADJUSTABLE PITCH. Employed 
in investigations of dielectric absorption, capacity measure- 
MVENES FEUG: 
39. AUTOMATIC VIBRATORY TRANSFORMER of direct into 
alternating currents of high and adjustable frequency. Em- 
ployed in investigations of electrical resonance and vacuum 
discharges. 
40. INERTIA COILS, employed in the study of low frequency 
electrical resonance and harmonic analysis of alternating 
currents. 
41. MICA CONDENSER, with very small subdivisions employed 
in the harmonic analysis of alternating currents. Total 
capacity 2 M. F-., smallest subdivision .oo094 M. F. 
42. Complete outfit for generating ELECTRICAL WAVES; vacuum 
tube WAVE DETECTORS. 
43. 50,000 VOLT TRANSFORMER, with oil insulation. Designed 
by the exhibitor. Constructed by Swinburne & Co., Ted- 
dington, Eng. Employed in investigations of disruptive 
discharges. 
44. HIGH VOLTAGE OSCILLATORY TRANSFORMER. 
45. THREE PHASE DYNAMO. Employed in the study of rotary 
magnetic fields. The field magnet of this machine is the 
movable part. It is constructed in such a way as to produce 
a field which is distributed uniformly over the pole-faces and 
to generate complex harmonic electromotive force of prede- 
termined form. 
45 a. ALTERNATING CURRENT MACHINE of 1.5 kilowatts. Gives 
400 periods per second and 2000 volts at normal speed. 
Designed by exhibitor and employed in researches on low 
frequency electrical resonance. Connected to transformer, 
inertia coil, mica condenser and electrostatic voltmeter, the 
