IX. WORK. 87 



both spindles are driving pulleys and friction breaks on Appold's system, by 

 means of which the force to be transmitted can be regulated. 



An amount of slipping of not more than the one hundred thousandth part 

 of the distance rolled can be measured with this machine. 



The machine was constructed in Owen's College by Mr. Foster. 



427. Phroso-dynamic Apparatus for testing wires, by 

 Mr. Alcun. M. Digeon, Pans. 



428. Von Jolly's Spring-balance. 



University of Munich, fyc. 



42 8b. Pieces of Steel Cylinders, torn by traction in expe- 

 riments made to ascertain the influence of mode of treatment on 

 the mechanical properties of steel. 



Imperial Technical Society in St. Petersburg. 



Annexed is a report on the experiments. Out of a block of unforged soft 

 cast steel were cut, in identical positions parallel to the axis, 16 bars which 

 were treated in heat or forging in eight different manners, two samples in 

 each way. The samples were then turned in shape of cylinders for traction 

 proof, and for each of them determined elastic and permanent elongations for 

 a series of increasing traction forces, density, hardness (by indentation), and 

 other elements. Results indicated in annexed diagrams and tables. 



IX. MEASUREMENT OF WORK. 



429. Dynamometer, graduated up to 100 kilogrammes by 

 intervals of 200 grammes, and showing dynams in kilometres up 

 to 981, each interval measuring two dyiiams nearly in absolute 

 measure. Prof. 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. Hennessy, Dublin. 



431. Drawing of a Dynamometrical Apparatus, con- 

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

 of steam-boats. P r f> Daniel Colladon, Geneva, 



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

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



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, 



