276 Mr. H. M. Macdonald on Electrical Vibrations 
of Metals.” In these the alterations in the mechanical pro- 
perties which resulted from oyerstrain were studied side by 
side with the corresponding alterations in the electro-chemical 
properties of the metal before and after overstrain. It was 
found “ that an average E.M.F. of 0:016 volt obtained between 
the strained and the unstrained portion of wrought-iron shafts 
under the conditions recorded.” The electr olyte used was a 
saturated solution of sodium chloride. The tensile strength 
of the iron used in these experiments was 22°83 tons 
per square inch before straining, and 30°02 tons after 
straining. 
XXVIII. On the Electrical Vibrations associated with thin 
terminated Conducting Rods. By H. M. Macpnonatnp, 
bie eA Ps 
VENTURE, with diffidence, to put forward the difficulties 
which I find in the views adopted by Lord Rayleigh in 
a recent note (Phil. Mag. July 1904, p. 105). In the first 
place there is a wide discrepancy between his result and that 
of experiment, which, so far as I know, does not place an 
electric loop at the free end of the wire. It is true that 
Kiebitz + has thought that this conclusion is involved in his 
result that the length of a ring resonator which he found to 
respond best to a straight wire vibrator is approximately the 
same as the length of the vibrator, but, as Prof. Pollock has 
remarked, such an inference does not follow. In fact 
Kiebitz’s result is in complete agreement with that of 
Sarasin and de la Rive, who found that when waves were 
being propagated along a straight wire with a free end, the 
distance of the first node from the free end of the wire was 
approximately equal to the half circumference of the re- 
sonator that responded to these waves. They, however, 
further found that the distance of the second node from the 
first was approximately four times the diameter of this re- 
sonator (2. e., somewhat greater than 24 times the half 
circumference), showing that the free end was not a true 
loop f. 
The only suggestion offered by Lord Rayleigh towards 
bee the discrepancy, namely, that the conductivity may 
* Communicated by the Author. 
+ Ann. der Physik, vy. 4, p. 872; vi. 4, p. 741 (1901). 
t Comptes Rendus, cx. 1890, 
