﻿576 Prof. Barton and Mr. Penzer on Simultaneous 



shape which gravity by itself can condition ; but the intensity 

 of which being less in consideration of the smaller bulk of 

 the asteroids, might entail [if this were the sole cause of 

 accretion] an internal structure less closely packed than in 

 the instance of our earth*. It appears, however, that what- 

 ever the existing structure of the asteroids, this structure 

 must at least be able to hold together against the existent 

 value of tidal action on these bodies. 

 September 2, 1906. 



LXV. Simultaneous Vibration- Curves of String and Air 

 photographically obtained from a Monochord. By Prof. E. 

 H. Baeton, D.Sc, F.R.S.E., and J. Penzer |. 



[Plate XIX.] 



SOME time ago it appeared to one of us desirable to 

 investigate the relations between the vibrations of a 

 string and those which consequently occur in the bridge, 

 sound-box, and contained air of the instrument on which the 

 string is mounted. In 1905 the first instalment J of this 

 work appeared and dealt with the motion of the belly and 

 the string of a monochord when bowed. The present paper 

 forms the second contribution to the entire problem, and is 

 concerned with the string and air in the sound-box of the 

 same monochord, both bowing and plucking being used in 

 contrast. 



Experimental Arrangements. 



The string's motion is here recorded by the same method 

 as in the former paper, and is shown in the positive prints 

 or their reproductions by a black line on a white ground, 

 the focussed shadow of the string rising and falling period- 

 ically on the lower portion of the photographic plate, as the 

 plate itself shoots uniformly along the horizontal. 



The motion of the air in and out of the sound-box was 



* In ' Science Abstracts ' (August 25, 1906, p. 894) is a communication 

 headed li Flow of Concrete under Pressure," abstracted from ' Eng. News,' 

 Nov. 2, 1905, in which an experiment by I. H. Woolson is described, 

 where a tube of steel containing set concrete (four inches in diameter) 

 widened to a diameter of five inches under pressure applied to the 

 concrete. It is added that, " On sawing the tube, the concrete is found 

 to have ' flowed ' like a plastic material and to have taken the exact shape 

 of the distorted tube. Reference is made to F. D. Adams, who has 

 shown that marble will flow in this way." (Amer. Geological Soc. 1901.) 



+ Communicated by the Authors. 



X Barton & Garrett, Phil. Mag. July 1905, pp. 149-157. 



