Indicator for High Speeds. 



67 



vivid, and to anyone accustomed to indicator-diagrams it is 

 an object of interest from quite a number of considerations. 



As 1 am unable to show to the Society this instrument in 

 action, I will throw upon the screen a photograph, fig. 3, 



Fi-. 3. 



taken at Finsbury of the indicator placed upon a toy steam- 

 engine, which some of my students made to drive testing 

 machines. My partner, Mr. Holland, is following the spot 

 of light with a pencil. As a matter of fact, the engine was 

 really at rest, and the diagram was drawn as a thick chalk 



F2 



