CONCLUDING REMARKS. 195 



ing the dynamic equivalents of different forces, and it is probable 

 that by its aid the best theoretical and practical results will be 

 ultimately attained. 



In investigating the relation of the different forces, I have 

 in turn taken each one as the initial force or starting-point, 

 and endeavoured to show how the force thus arbitrarily se 

 lected could mediately or immediately produce and be merged 

 into the others : but it will be obvious to those who have at 

 tentively considered the subject, and brought their minds into 

 a general accordance with the views I have submitted to them, 

 that no force can, strictly speaking, be initial, as there must 

 be some anterior force which produced it : we cannot create 

 force or motion any more than we can create matter. 



Thus, to take an example previously noticed, and recede 

 backwards ; the spark of light is produced by electricity, 

 electricity by motion, and motion is produced by something 

 else, say a steam-engine that is, by heat. This heat is pro 

 duced by chemical affinity, i.e. the affinity of the carbon of 

 the coal for the oxygen of the air : this carbon and this oxy 

 gen have been previously eliminated by actions difficult to 

 trace, but of the pre-existence of which we cannot doubt, 

 and in which actions we should find the conjoint and al 

 ternating effects of heat, light, chemical affinity, &c. Thus, 

 tracing any force backwards to its antecedents, we are merged 

 in an infinity of changing forms of force ; at some point we 

 lose it, not because it has been in fact created at any definite 

 point, but because it resolves itself into so many contributing 

 forces, that the evidence of it is lost to our senses or powers 

 of detection ; just as in following it forward into the effect it 

 produces, it becomes, as I have before stated, so subdivided 

 and dissipated as to be equally lost to our means of detection. 



Can we, indeed, suggest a proposition, definitely conceiv 

 able by the mind, of force without antecedent force ? I can 

 not, without calling for the interposition of created power, 

 any more than I can conceive the sudden appearance of a 



