THE WORLD'S CEREAL AND FOOD-CROPS 49 
implied by a rate of increase, and how fallacious is the 
common notion that the recent rates of increase of 
the earth’s inhabitants—given above—are by no means 
ominous. At the same time it has to be borne in 
mind that, as the earth’s population increases, the 
difficulty of maintaining the same rate of increase also 
becomes greater. 
torical period of the development of the human race, it was known 
that its rate of increase had averaged sensibly I per cent. per annum. 
Yet such a statement would be the wildest absurdity, for, taking this 
as 10,000 years, the whole of the solar system, multiplied many 
times over, would not make bodies for the population numbers so 
reached. 
For computers it may be of interest to note that an increase of even 
1 per cent. leads to large numbers. The log. 1-017%%0° is 43-213738, 
that is, it is the logarithm of 16,358,290, followed by 36 noughts. 
The earth’s average density is about 5-527 times that of water. If we 
take the latter to weigh 62-321 lbs. per cubic foot, then the earth 
weights about 344-48 lbs. per cubic foot of volume on the average. 
From its dimensions it is thus easy to obtain its total mass. One finds 
in this way that the logarithm of the number of earths necessary to 
provide bodies, each of 100 lbs. weight, for the population from a 
couple, increasing for ten thousand years continually at the rate of 
I per cent. per annum, would be no less than 20°3949644, that is 
the number is 248,293,000,000,000,000,000, and this would be the 
number of earths required to provide material for their bodies. 
It may be mentioned that during the period 190g to 1923 the earth’s 
population increased from about 1679-9 millions to about 1841-0 
millions, say annually at the rate of 0-656 per cent. or roughly two- 
thirds of a per cent. per annum. The numbers reached, if this rate, 
and the larger rate of 1-16 per cent. were maintained, are worthy of 
note. ‘They mean the doubling of the population in respectively 
104-32 and 60-1 years. Starting with 1950 millions for 1928, these 
rates would give the following populations in millions at the dates 
indicated hereunder :— 
Date-year . . 1928 2028 2128 2228 2328 
Increase, % per cent. 1950 3,790 7,365 I4,313*% 27,817% 
Increase, 1-16 per cent. 1950 6,179 19,579% 62,041% 196,590% 
The populations marked with asterisks are not possible for the earth. 
We see from these figures that, with the lower rate, the population 
would be increased nearly 14-3 times, and with the higher rate over 
108 times, in four centuries!