FE. Nipher—Evolution of American Trotting Horse. 21 
erence to real physical conditions, it determines the date when 
the amount of horseflesh capable of making this speed had 
i. 
log. N. 
3°0 
1840 
Mncreased to one horse. It is clear that this date, based as it is 
upon all the succeeding values through a series of years, is 
much more reliable than the date when some accidentally occur- 
Ting trotting match revealed the fact that the horse capable of 
making the speed had already come. 
yet be determined very exactly, and in the following discussion 
this is to be borne in mind. The same holds true for speeds 
‘of the various speeds, where s represents the time required to 
— is given, being calculated in a well known manner from : 
alternate differences in the first two columns. 
