248 



PROCEEDINGS OF SECTION C. 



the number on the logarithm scale, expressing the factor of exaggera- 

 tion. The value so found is the magnitude of the angle which has 

 to be plotted on the exaggerated section. 



It is an advantage to mount the slide way on a strip of board, 

 which prevents wai-ping, and gives " body" to the instrument. 



PLATE I. 



\ \/m//////j////iTTTjm ^ 



h|m 



80 L. cosine 3cale45 100 

 Logarithm scale 



giR.» 2 ' 



^ 



^fcl 



Fig' ^' 



Fig. 1.— Slide Way (plan) showing arrangement of logarithmic tangent and 

 logarithm scales. The graduations are diagrammatic only. Shaded area is depressed 

 portion. 



Fig. 2.— Plan of slide showing diagrammatic-ally arrangement of logarithr 

 and logarithm scales. 



Fig. 3.— Section of slide way. Thickness of strips is exaggerated. 



Fig. 4. — Section of slide. 



imic cosine 



