67

O.60

speech, and with it articulate thought;—not to take into account the sluggishness of inquiry in by-gone ages. Yet the fact is that in the history of general physics and chemistry, the branches I am best acquainted with, instead of its having been necessary to investigate and reject many thousands of independent hypotheses to account for each general phenomenon, there have been very few for which more than three or four were necessary, on the average less than three, I should say. How is that to be accounted for? Is it