IX. WORK. 109 



IX. MEASUREMENT OF WORK. 



429. Dynamometer, graduated up to 100 kilogrammes by 

 intervals of 200 grammes, and showing dynams in kilogrammetres 

 up to 981, each interval measuring two dynams nearly in absolute 

 measure. P r f> Hennessy, Dublin. 



430. Dynamometer graduated up to 10 kilogrammes, and 

 giving absolute dynams in kilogrammetres up to 98, each interval 

 measuring nearly one dynam in absolute measure. 



Prof. Hcnnessy, Dublin. 



Dynamometers similar to these are are employed at the Royal College of 

 Science. Dublin, as referred to in the College Directory for 1876-77, page 17. 



" The dyuam or unit of force commonly employed throughout the course is 

 one kilogramme moving through one metre in one second of time." 



430a. Photograph of Electrodynamometer. Made by 

 Professor H. A. Rowland, Johns Hopkins University, Baltimore, 

 on the model of that of the British Association. 



Cavendish Laboratory, Cambridge. 



431. Drawing of a Dynamometrical Apparatus, con- 

 structed in 1844 by the exhibitor, to measure the real horse-power 

 of steam-boats. Prof. Daniel Colladon, Geneva. 



This apparatus, approved by the Academie des Sciences in 1843, was, in 

 the same year, adopted in the IJoyal Dockyard at Woolwich. 



644. Surface Spring Indicator. 



H. Hadicke, Demmin, Pomerania. 



The indicator was constructed by the exhibitor, and executed from his 

 drawings by Messrs. Blanche and Co., in Merseburg. The piston has been 

 replaced by a surface spring, and the construction aims at 



1. Avoiding the friction of the piston of the indicators hitherto in use. 



2. Avoiding the slackness of the piston. 



3. Avoiding the points of the diagram of machines in rapid motion 



produced by the mechanical momentum of the piston. 



432. Richard's Patent Steam Engine Indicator, with 

 Darke's Patent Detent and Cord Adjuster. Elliott Brothers. 



By means of the detent, the paper cylinder is instantaneously set in motion 

 or stopped by the movement of the pencil arm, as it is being applied or with- 

 drawn, giving great facilities for taking a number of consecutive diagrams, 

 also rendering its application to oscillating engines much more convenient. 



433. Cooper's Patent Slide Valve Indicator. An in- 

 strument for ascertaining the relative position between the piston 

 and slide valve of an engine at different points of the stroke. 



Elliott Brothers, 



