II. ELEMENTARY ILLUSTRATIONS. 117 



289. Chamber-wheel train, Fabry. 



290. Chamber-wheel train, Root. 



Blower. 



291. Chamber-wheel train, Root. 



Blower. 



292. Chamber- wheel train, Pay ton. 



Water-meter. 



293. Chamber-wheel train, Evrard. 



Pump. 



294. Chamber- wheel train, Repsold, Lecocq. 



Pump. 



295. Chamber-wheel train, Dart, Behrens. 



Pump. 



296. Chamber-wheel train, Ganahl, Eve. 



297. Chamber-wheel train, with three wheels. 



298. Screw-wheel chamber train, Revillion. 



Ventilator. 



H. ELEMENTARY ILLUSTRATIONS. 



528a. Parallelogram of Forces. 



Dr. G. Krebs, Frankfort-on-the- Maine. 

 528b. Inclined Plane. 



Dr. G. Krebsj Frankfort-on-the- Maine. 



528c. Inclined Plane, constructed by Professor Dr. Bertram, 

 Councillor of the Board of Education. Ferdinand Ernecke, Berlin. 



The inclined plane is represented by two parallel iron rods, which can be 

 placed at any angle desirable to the horizontal bar. 



Three tracts (distances) can be measured on the same : 



1. The length of the inclined plane, that is to say, the distance from the 

 turning point (centre of motion) to the perpendicular iron support bar, which 

 maintains the plane in its proper position. 



2. The base, that is to say, the horizontal distance from the csntre of motion 

 to the support bar ; the same is read on the horizontal pedestal. 



3. The height, that is to say, the plumb line from the terminal point of the 

 first distance to a horizontal line laid through the centre of motion ; this 

 is read on the support bar, the zero point of which is situated on a level with 

 the centre of motion. 



The burden on the inclined plane can be arrested in two different ways : 

 either by a motion parallel to the inclined plane, or by a horizontal motion. 

 The carriage of the roller can be turned, and the pulling string can, therefore, 

 be placed parallel to the inclined planes or horizontally. The double division 

 on the slitted support bar serves for observing the horizontal position of the 

 string. 



At every experiment the burden carriage, that is, the two-wheeled axle 

 with its scale, is balanced with the scale which is suspended on the string. 

 This is effected by tare weights. Then the burden and the power of traction 

 is adjusted by means of the measured distances, that is to say, the weights 

 which are balancing each other in the burden scale and the traction scale. 



1. If the string of the inclined plane runs parallel, then the burden is 



