Rejwrt on the Trials of Imjplements at Bedford. 679 



is a rising gradient of 1 in 1000. The road might be con- 

 sidered a fair average of what is met with in practice : it 

 was mainly made up of gravel, and although it was very 

 dry during the entire trial, still it was somewhat soft, and 

 offered a good deal more resistance than would be met with 

 on a road made up of broken metal. 



The field course was through a field of oats. The ground 

 was very dry, but soft ; and represented a fair average of 

 stubble-fields in a dry autumn, but hardly an average for wet 

 and dry all the year round. 



The waggons and carts were each attached to the horse 

 dynamometer, which was drawn by horses over the course ; 

 and to enable the reader to understand how the draughts 

 were registered, a short description of the instrument is now 

 given. 



In the horse dynamometer (Figs. 16 and 17, pp. 680 and 681) 

 we have almost a complete imitation of an ordinary draught-horse ; 

 the saddle-chain being passed over an imitation wrought-iron 

 saddle, P, and the vehicle drawn by draught-chains, F, attached 

 on each side to a draught-plate, E, in imitation of the horse's 

 collar at the point of the shoulder. 



This swivelling draught-plate E is looselyjointed to the spindle 

 of the instrument by a pin passing through both, and beneath 

 the plate are castors, G, G, which run on a bed-plate. 



The spindle is coupled in front to a spring, A, formed of two 

 untempered cast-steel plates connected at their ends, the front 

 plate being connected with the frame of the instrument. The 

 spindle is guided in front by a bracket, G, and behind by an oil 

 cylinder, D, filled with oil, the flow of which from end to end is 

 regulated by a screw plug fitted to the communicating passage. 

 The lever H has its fulcrum on the bed-plate, oscillating freely 

 on this point. At its first third it passes through a slot in the 

 spindle, to which it is jointed by links and pins ; at its upper 

 end it is connected to a counter bar, which bears the inte- 

 grating disc K, thus any movement on the spindle is multiplied 

 three times on the counter bar. The counter bar is attached at 

 its front end to a moving index, M ; at its outer end it will also 

 carry a suitable arm having a metallic pencil at its end, which 

 will describe the variations of draught on a sheet of metallic 

 paper wound round the cylinder N, which is set in motion at 

 will at a speed proportional to the distance travelled. A large 

 disc, L, is connected with the hind wheels of the instrument by a 

 bevel gearing, and is thus driven at one revolution for every yard 

 run. By a spring this large disc is kept in continual contact 

 with a small integrating disc, K, placed at right angles to the 

 former and attached to the movable counter bar. It is evident. 



