1058 Mr. E. J. Hartung on the Construction and 



Grant (fig. 1, 0). It is inherently heavier for the same 

 strength becanse the material is less economically distributed, 

 and the absence of the vertical rod connecting the upper and 

 lower portions probably increases the tendency to fail laterally 

 under load. Further, the placing of the knife-edges at the 

 end of a comparatively long pillar attached by only one 



KJr. l. 



complex joint to the rest of the structure is a device of 

 problematical value. In order to test the limitations of the 

 double-triangle beam, a balance of this type was constructed 

 with a single knife-edge about 0*4 mm. long. The members 

 from which the beam was made were carefully selected, and 

 special pains were taken to fuse them together strictly in one 

 plane. The instrument was adjusted so that its period of 

 oscillation was about 90 seconds, and it was then capable of 

 detecting a difference of l/i in a load of 40 mg. This 



