[ 91 ] 
nuing together only 134. years. But the expeBatiou 
of two equal joint lives being (according to the fame 
hypothefis) always a third of the mnmon complement.^ 
it is in this cafe 1 54 years. It is necefiary, therefore, 
to obferve, that there is another fenfe of this phrafe 
which ought to be carefully diftinguifhed from that 
now mentioned. It may fignify “ The mean confi- 
nuance Qi any given Jingle., joint or jurvivingXwt^^ 
“ according to any given table of obfervations that 
is, the number of years which, taking them one with- 
another, they adtually enjoy, and may be confidered 
as fure of enjoying, thofe who live or furvive beyofid 
that period, enjoying as much more time in proportion 
to their number, as thofe who fall fiort of it enjoy 
lefi. Thus, Suppofing 46 perfons alive, all 40 years 
of age, and that, according to Mr. De Moivre’s hy^ 
pothefs, one will die every year till they are all dead 
in 46 years, half 46 or 23 will be their expeSlation of 
life : that is ; The number of years enjoyed by them 
all will be juft the fame as if every one of them had 
lived 23 years, and then died j fo thatj fuppofing no 
intereft of money, there would be no difference in va- 
lue between annuities payable for life to every fingle 
perfon in fuch a fet, and equal annuities payable to 
another equal fet of perfons of the fame common 
age, fuppofed to be all fure of living juft 23 years and 
no more. 
excellent hypothejis. It -eafes exceedingly the labour of calcu- 
lating the values of lives. It is remarkably agreeable to Dr. 
Halley’s Table of Obfervations ; and, as far as it implies an 
equal decrement of life, is, in a great meafure, confirmed by 
other Tables. 
N 2 In 
