CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL 

 LABORATORY, HARVARD UNIVERSITY. 



EXPERIMENTS ON THE ELECTRICAL OSCILLATIONS OF 

 A HERTZ RECTILINEAR OSCILLATOR. 



By George W. Pierce. 



Presented December 8, 1909. Received January 3, 1910. 



While engaged in calibrating a wavemeter for electric waves, I have 

 made a series of measurements of the wave-length produced by a long 

 Hertz rectilinear oscillator, consisting of two oppositely extending hori- 

 zontal wires with a spark-gap between. By varying the length of the 

 oscillator, wave-lengths from 16 to 63 meters were obtained. The ex- 

 periments were conducted in a long room in the third story of the 

 laboratory, so that the oscillator was at a height of 10 meters above 

 the surface of the earth, and represents approximately the conditions 

 that exist when the oscillator is alone in free space. 



The experimental results, which give a relation of the wave-length 

 to the length of the oscillator, may be not without interest ; because of 

 the existence of numerous very thorough mathematical discussions 

 of the problem. 



Apparatus and Plan of the Experiment. — A general idea of the 

 experiment may be had by a reference to Fig. 1, which shows in ground 

 plan the arrangement of the apparatus. 



The wavemeter, shown at the left of the figure, consists of a variable 

 condenser C in series with a loop of heavy wire L and a high-frequency 

 electrodynamometer I. The loop of wire L is in the form of a square 

 30 cm. on a side. The condenser consists of two sets of semicircular 

 plates — one set fixed and the other set movable by rotation about a 

 vertical axis so as to permit variation of capacity by bringing a greater 

 or less area of the two sets of plates into an interlapping position. A 

 scale carried by the top movable plate passes under a fixed pointer, so 

 that the position of the movable plates with respect to the fixed plates 

 can be read after any adjustment of the apparatus. 



The high-frequency dynamometer I is of the form previously em- 

 ployed by me in a series of experiments on resonance in wireless tele- 



