45, COBNHILL, E.C., AND 122, BEGENT STREET, W., LONDON. 199 



FlG. 578. FIG. 587*. 



587 The Patent " Concentric " Steam Engine Indicator, (figs. 587 & 587*) Negretti 

 and Zambra call the attention of Engineers to great improvements in the new " Con- 

 centric " Indicator, which reduces the vibration of the instrument to a minimum. 



The paper drum is arranged in such a manner that it revolves concentrically 

 with the piston cylinder. The pull action is direct upon the coupling which 

 connects it to the cylinder of the engine. This arrangement causes less vibration 

 to the instrument than if the drum were fixed on an arm, as in the ordinary form 

 of Richard's Steam Engine Indicator. 



A small instrument is made especially for high speeds, to which this indicator 

 is particularly adapted. 



