EXPERIMENTS OF 1834. 91 



bodies, and in the same circmnstances, as indicated by tlie compensating dyna- 

 mometers, wiU shew the comparative efifects of a variation in the action of the 

 power. 



Example I. Example K. 



Trotting, 



Cantering, 



Force indicated. 



195 lb. I 

 100 ... > Mean = 101 lb. 

 108... \ 

 Same Telocity. 

 138.. 



152 ... S Mean = 101 lb. 

 165 ... 



Force indicated. 



Trotting, 



Cantering, 



67'. Space = 1000 feet. 



66'. Space = 1000 feet. 



The specimen of the dynamical effect of trotting which I have given in Ex- 

 ample II., is the most perfect specimen I have ever been able to obtain, and was 

 obtained by a very powerful weU-bred, weU-trained horse, which was ridden m a 

 very superior manner. Out of an mimense number of experiments made with 

 horse-power, I have been able to obtain comparatively few in which the differences 

 of the successive impulses were sufficiently small to admit of an arithmetical 

 mean being used to represent a constant force. All the others were of com-se 

 comparatively valueless, except as illustrative of the manner in which the power of 

 horses was applied in overcoming the peculiar mode of resistance of the flmd. 



Although, therefore, dm-ing 1834, I made a very great number of experiments 

 on the resistance of various vessels, in various conditions of immersion and at 

 many different velocities, in which the direct power of horses was apphed, and 

 measm-ed by the action of the dynamometer I have described as the fluid djTia- 

 mometer, and with the ordinary dynamometer, I am now disposed to place little 

 faith in those where the application of the force deviated widely from uniformity, 

 especially when absolute measures of the resistances are requu-ed, or delicate 

 comparisons instituted. For observations on which we may rely hnphcitly as mea- 

 sm-es of resistance, I refer with perfect confidence to the experiments of 183o, 

 which were made .vith contmuous power, and under the improved arrangements 

 which the experience of 1834 had dictated. I give here, however, a set of expe- 

 riments of 1834, which were obtained after long experience had enabled us to 

 render the variations of om- desultory power as small as possible, assigning to 

 them that degi-ee of value only which the approximation to uniformity may ap- 

 pear to entitle them. 



