C. GENERAL PHYSICS. 145 



the atmosphere along with a jet of air or vapor. Any such 

 jet, blown from a fine spout, carries with it a certain quanti- 

 ty of the surrounding air. From' an extensive series of ac- 

 curate measurements made by him, he concludes in general 

 that when the jet is received through a tube into a chamber 

 pierced opposite to the receiving spout by an orifice equal 

 and similar to it, the pressure within the chamber is re- 

 duced to one half. Second, that whatever distance the ori- 

 fice of the spout may be, the efiect is always greater if the 

 direction of the jet is the same as that of the axis. In all 

 directions inclined to the axis the effect diminishes verv 

 rapidly. The experiments made by him have included the 

 use of conical and cylindrical tubes, and open and closed 

 reservoirs. 6 B^ LXXX., 189. 



EXTENDING THE COMPASS AND INCREASING THE TONE OF 



STRINGED INSTRUMENTS. 



At a recent meeting of the Musical Association of London, 

 Dr. Stone stated that there are three ways in which a string 

 may be made to give very slow vibrations, viz., by increas- 

 ing its length, its thickness, or its density. He had adopted 

 the third plan by covering a catgut string with heavy cop- 

 per wire, which proved to be fairly successful. This had been 

 improved upon by re-enforcing the vibrations by means of 

 longitudinal struts or bars, applied to the double bass violin. 

 Four strips of white-wood, curved to an elliptical figure, are 

 passed parallel from end to end, on the inside of the belly of 

 the violin. The result is the removal of what is termed by 

 the musicians "wolf," or inequality and falseness of tone, 

 with a great increase of power throughout the range of the 

 instrument. The same process is equally applicable to small 

 violins, and the bars can be removed at pleasure without 

 damaging the instrument. As an illustration of what may 

 be effected by this system, an instrument whose original cost 

 Avas \s. 9<r7. was exhibited to which this improvement had 

 been applied, and its performances called forth great ap- 

 plause. IS A, XX., 270. 



CONDUCTION OF HEAT BY BUILDING MATERIALS. 



The coeflicient of conduction for heat of various building 

 materials has lately been carefully investigated by Lang, 



G 



