66 
TRANSACTIONS OF THE TEXAS ACADEMY OF SCIENCE. 
tigated, I have found these forced vibrations and critical lengths with 
various sized resonators. Thomson’s view, so far as I can see, would 
demand that these nodes should always have the same position and in- 
tensity in all wires. With my present knowledge of the subject, I find 
no view of the action of the oscillator so satisfactory in accounting for 
all the phenomena as that which regards it as emitting a somewhat per- 
sistent and complex, though constant, rate of wave motions. Hertz ap- 
parently regarded its action as being made up chiefly of one single definite 
oscillation, whose time depended upon the formula T = - Vpc / A; 
though he states that this is accompanied by certain irregular disturb- 
ances. Thomson appears to agree with him in every respect, save that of 
the persistence of the vibration. Both recognize the fact that it is rapidly 
damped, yet from Hertz’s standpoint they have sufficient duration to 
produce appreciable standing waves, while Thomson denies their exist- 
ence. Thinking that possibly some further light might he obtained by 
a careful study of the resonance effects of this oscillation, I have been at 
considerable pains to carefully construct a few resonance curves for va- 
rious types of vibrators. The resonance curve which Hertz gives in his 
work indicates a simple and rather continuous oscillation, unaccom- 
panied by any very serious irregularities. This curve is reproduced in 
Fig. 2. The abscissae represent the lengths of wire in the various reson- 
ators examined, and the ordinates the corresponding maximum spark 
lengths. Unfortunately, he did not give us a curve of the resonance of 
the type of vibrator used in his most celebrated experiments. He only 
states that a resonator of 220 c.m. was found to he in tune with it. As- 
suming this to he a correct maximum, we would expect a minimum for a 
length of 440, and a second maximum at 660. Line AX in Fig. 4 is de- 
signed to show what was to be expected if the observations should agree 
both with Hertz’s curve in a former case and his statements concerning 
this particular vibrator. According to Thomson’s view, we could scarcely 
expect any appreciable curve at all. To determine the relative merits of 
these two hypotheses a number of careful experiments have been made, 
Fig. 3 being a copy of the original record sheet. Hertz’s method for 
determining resonance effects was to place the resonator at a fixed dis- 
tance from the vibrator, and to measure the maximum spark that was 
produced by different lengths of wire. My experience in measuring max- 
imum spark lengths is that they are so variable that no very satisfactory 
results can he obtained. A much more constant method is to fix the gap 
at a convenient length and then to determine the maximum distance to 
which the resonator can he carried before the spark is extinguished. 
Even this method wi.ll sometimes give very discrepant results unless it is 
known how the vibrator has varied in its action during the period of oh- 
