272 Mr Harvey on the Methods employed [for examining 
prove that some mystery hung over the returns of the male popu- 
lation of St Andrew, because the marriages and baptisms of this 
parish had received very large additions during the preceding 
ten years ; and the register of burials for the same period also 
proved, that no undue rate of mortality had prevailed, so as in 
any way to account for a decrement in its population. To dis- 
cover, therefore, the probable cause of the anomaly, it was deem- 
ed expedient to submit the returns of each parish to the test of 
the same law ; and for this purpose, the principle was employed, 
of supposing the annual average excess of baptisms above bu- 
rials , to bear a constant ratio to the contemporaneous popula- 
tion ; and the proper application of which theory, furnishes the 
equation 
A = P(1 + Z)«, 
in which A denotes the present population of a parish, P the 
amount of its population, when the former enumeration was 
made, n the elapsed interval in years, and l the number arising 
from the division of the average annual excess of baptisms above 
burials, by the antecedent population of the place. In the pre- 
sent case, the values of these elements are as follows, for the re- 
spective parishes : 
St Andrew. Charles. 
P = 12339 P = 8464 
n=z 10 n= 10 
l = .0106 l — .0106 
Hence, by adapting the representative equation for the present 
state of the population to logarithms, it will assume the form 
of 
IA = IP + n /(I + 
and which, by applying the numerical elements for the respec- 
tive parishes, will furnish the following calculation for St An- 
drew : 
IP = H2339 = 4-0902800 
n Z(1 + 1) = 10 1 1 0106 = 0 0457930 
IA = 13680 = 4 1360730 
and a similar application will likewise afford the following for 
Charles : 
