GLACIAL EPOCH UPON THE EARLY HISTORY OF MANKIND. 69" 
has long since made a name in the field of geologic science. He 
has here proved by solid research and experiment, made both by 
others and by himself, that the whole period of human existence 
upon the Earth is far shorter than recent geologists have maintained, 
and approaches much nearer to the extent that we infer for it from 
a study of the Bible. 
I would ask, however, whether the result that apparently flows 
from Dr. Gilbert’s measured annual recession of Niagara Falls — 
namely, a period of 7,000 years for its total recession — may not at 
once be greatly reduced by taking into account the relative thickness^ 
of compact rock in the uppermost hundred yards where the recession 
has been measured, and which is close upon 80 feet, and the average 
thickness for the whole course of seven miles [which I find to be 
only about 66. The recession probably started from the complete- 
break-up of the Glacial Epoch, so I await a still further reduction in 
the reckoning]. Meanwhile, it can be proved in another way that, 
the human period is vastly shorter than is supposed by many 
scientists who ignore the figures that have come down to us in the 
Bible. 
Taking an estimate given by Lord Avebury in 1904* (which is- 
only a third of the one given by Professor Kay Lankester last 
year]f — namely, that mankind had been upon the Earth 50,000 
y ears — let us find what average yearly increase would produce in 
that '-period from an original human pair the population of the 
world as it stands now — that is (according to the last census for all 
civilised peoples and according to expert calculations for all 
barbarous ones) 1,564,000,0004 
Let — - stand for the unknown yearly increase. Then every 
x 
unit in each successive year has become 1 + ; and this process- 
tl/ 
has been repeated 50,000 times. 
* At the meeting of the British Association, in a discussion upon a 
paper by Dr. Arthur Evans upon the Chronology of Crete, 
t In his Romanes lecture. 
+ From Pannell’s Reference Book (Granville Press, 1900). 
