THE 



Ohio Journal of Science 



PUBLISHED BY THE 



Ohio State University Scientific Society 

 Volume XVIII MARCH, 1918 No. 5 



TABLE OF CONTENTS 



Blakk and Jackson — The Relative Intensity of the Harmonics of a Lecher 



System (Experimental) 145 



Blake — The Relative Intensity of Harmonics of alLecher System (Theoretical) 163 



Sterki — Inland Mollusks 169 



Drake — Two New Tingids from the West Indies (Hem -Heter) 174 



THE RELATIVE INTENSITY OF THE HARMONICS OF 

 A LECHER SYSTEM. (EXPERIMENTAL). 



By F. C. Blake and B. H. Jackson. 



In their fourth paper* on the free vibrations of a Lecher 

 system, Blake and Sheard have shown how the tone intensity 

 depends very much upon the edge-on distance between the 

 plates, but they were unable on account of oscillator deteriora- 

 tion among other things to summarize this relation. We have 

 made a careful study of the various factors that help to deter- 

 mine the tone intensity and present the results of our study in 

 this paper. 



I. Apparatus. 



The apparatus used was that employed by Blake and Sheard 

 except that the brass plates used were 1 mm. thick instead of 

 4.5 mm. It is shown diagrammatically in Figure 1, where the 

 letters are the same as in Figure 1 of Blake and Sheard's paper 

 IV. This necessitated making eight small holes in pairs through 

 the plates around the circumference through which the strings 

 were passed and knotted. The diameter of each hole was about 

 0.6 mm. while that of the plates was 5.0 cm. The total area of 

 the holes was thus about 0.4 per cent of the area of the plate, 



* Physical Review, N. S., IX, p. 177, 1917. 



145 



