NATURAL HISTORY. 
27 
period into two periods of ten years each^ and then 
have taken the average number. 
PROPORTION OF BIRTHS TO DEATHS. 
1801—1811, as 14 to 10. 1811—1821, as 147 to 100.^ 
From hence^ by a table of Euler's^ taking the 
excess of births above the deaths^ and comparing it 
with the whole population^ we determine that the 
city of Worcester^ supposing the present ratio of 
increase to continue, will double its population in 
sixty-six years. 
The most curious fact exhibited by these returns, 
is the decrease in the ratio of burials to the whole 
population. 
This ratio stands thus : 
1801, as 1 to 32.— 1811, as 1 to 43.-1821 as 1 to 48. 
The number of births in 1801, was in the ratio of 
1 to 31 to the whole population ; and in 1821, as 1 
to 30 ; from hence we may conclude that the great 
increase of population is rather to be attributed to 
the decrease in the number of deaths, or to the 
prolongation of human life, than to the increase in 
the number of births. 
I draw these conclusions, trusting to the exactness 
of the returns, and though, in many cases, they may 
be incorrect, yet, after every allowance we may feel 
* I cannot carry the calculation down to 1831, as the births, deaths and 
marriages, are not given in the comparative account of the population published 
in 1831. 
