t.] ANTECEDENTS. 9
in point of time and by doing so they become leaders of thought. They direct the intellectual energy of the day into the channels they opened ; it would have run in other channels but for their labour. It is therefore due to them, not that science progresses, but that her progress is as rapid as it is, and in the direction towards which they themselves have striven. We must neither underrate nor overrate their achievements. I would compare the small band of men who have achieved a conspicuous scientific position, to islands, which are not the detached objects they appear to the vulgar eye, but only the uppermost portions of hills, whose bulk is unseen. To pursue this metaphor ; the range of my inquiry dips a few fathoms below the level at which popular reputation begins.
It is of interest to know the ratio which the numbers of the leading scientific men bear to the population of England generally. I obtain it in this way. Although 180 persons only were on my list, I reckon, as already mentioned, that it would have been possible to have in-
