DURATION or HUMAN LIFE. 43 
Our late Prefident, the illuftrious Franklin, was of opi- 
nion, that the people of thefe ftates double their number 
in twenty years.* Dr. Price feems to think---that, “ in 
the back fettlements, where the inhabitants apply them- 
felves entirely to agriculture, and luxury is not known, 
they double their own numbers in fifteen years; and all 
through the Northern colonies, in twenty-five years ;---- 
which, continues Dr. Price, is an inftance of increafe fo 
rapid, as to have fcarcely any parallel.’---Even in Ma- 
deira---where, according to Dr. Heberden, only .. part 
of all the inhabitants die annually,---it is faid they do not 
double their number in lefs than eighty-four years. 
To affift us in forming a fatisfactory judgment, refpect- 
ing the probabilities of the duration of life, in this coun- 
try---a confideration intimately connected, in the prefent 
enquiry, with the caufes of the quick progrefs of its po- 
pulation,--~it becomes neceflary to examine into the} lon- 
gevity of the inhabitants.---Having noticed, in the pre- 
ceding part of thefe obfervations, that nearly one half of 
the people, in the Northern and middle ftates of the union, 
are under fixteen years of age—although Dr. Halley 
{tates, that,in Europe, the proportion of fuch is only one- 
third----the inference, neceflarily refulting from thefe 
facts, is---either, that the probability of the continuance 
of life is greater here than in Europe, between the birth 
and fixteen years of age, out of equal numbers born; or, 
if the probabilities are equal, prior to that period of life, 
inthe two countries ref{pectively—that the proportion of 
births to the number of inhabitants, here, exceeds that in 
Europe ;---or, on the other hand, that the probabilities of 
life are lower in this country, fubfequent to that period. 
F;,2 From 
* Obfervations concerning the increafe of mankind, peopling of countries, Xc. 
¢ ‘* Thofe inhabitants of Pennfylvania, who have acquired the arts of conforming to the 
ehanges of our weather, in drefs, diet, and manners, efcape moft of thofe acute difeafes, which 
are occafioned by the fenfible qualities of the air: and faithful enquiries and obfervations have 
proved, that they attain to as great ages, as the fame number of people in any part of the 
world.”’----Dr. Ruth’s account of the climate of Pennfylvania, &c. 
