The Problem Stated 23 



Let us state the matter in another way. 

 At the beginning of the nineteenth century 

 the extreme trotting speed was a trifle slower 

 than a mile in three minutes. At the begin- 

 ning of the twentieth century the extreme 

 speed was a trifle faster than a mile in two 

 minutes. The available energy in the horse 

 of to-day is greater than that of the horse of 

 a century ago by a ratio somewhat greater 

 than the square of three to the square of two. 

 The ordinary horse generation is ten years 

 in the male line, but the particular line 

 through which we get our two-minute 

 trotters averages about fourteen years per 

 generation. This makes seven generations 

 in which to make a gain of a little over a 

 minute, or an average gain of nine seconds 

 per generation. The gain in speed, and 

 consequently in the amount of available 

 energy, is not quite uniform, but the 

 general trend of it may be observed from 

 the following table, which gives part of the 

 champions at different dates, and the records 

 they made. 



