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and of all intermediate years has to be deduced. Successive
censuses have shewn that, for the last fifty years or more, the
population of England has steadily increased, and that the rate
of increase has been such as to enable statisticians to calculate
with some degree of success the successive annual additions to
the population. The same may be stated with respect to the
metropolis. And the same, though from the smaller numbers
involved and other associated sources of fallacy in a much
less degree, holds good generally with respect to smaller populations,
such as those of parishes, of districts, and of sub-districts.
The last census having shewn that there was in London on
the 8th April, 1861, a population of 2,803,989, and that during
the previous ten years the increase had been at the annual rate
of 1.73* per cent., the Registrar General, assuming that this is
still the rate of increase, calculates that the population of
London in the middle of 1863, was—not 2,803,989—but
2,803,989+100,424, or 2,904,413 ; and he estimates the deathrate
not on the number of persons living at the time of the
census, but on the population expressed by the latter and larger
number. Again, the year 1863 contained 53 Saturdays instead
of 52, and thus, since the local Registrars' returns are made up
weekly, comprised the mortality of 371 days instead of 364.
The actual length of a year is 365.2422 days And hence, in
estimating the death-rate of the year, the Registrar General
makes a further correction, he reduces the total number of
deaths returned in the ratio of 371 to 365.2422. By these
two procedures, of which one increases the number of the population,
while the other diminishes the number of deaths, the
death-rate becomes, and very properly, much reduced from that
* The increase per cent. per decennium was 18.7, which is equal to an
increase of 1.73 per cent. per annum for ten years.