336 Mr, Morgan 
Mr. Simpson, in his Treatife on Annuities and Rever- 
fions * has given a curve whofe area determines the probabi- 
lity of furvivorfhip between two perfons according to any table 
of obfervations. If one of the lives be not very young fo 
that the equidiftant ordinates may not be too few, this area is 
fufficiently correct. But if the eldeft of the two lives is under 
20 years of age, it becomes neceffary to affume fo many equi- 
diftant ordinates to render the folution accurate, when the de~ 
crements of life are unequal, that the operation is rendered 
much too laborious for ufe ; nor do 1 know that it can be ne- 
ceflary to have recourfe to this area in any cafe, efpecially as 
the true probabilities of furvivorfhip are fo eafily computed 
from the preceding feries. 
The following table has been formed in the manner de- 
fcribed above ; and as no fuch table has ever been attempted 
before, I have been the more defirous to render it complete, by 
computing the probabilities of furvivorfhip between two per- 
fons of all ages, whofe common difference is not lefs than 
ten years. 
Inftead alfo of fuppofing certainty to be denoted by unity, 
I have affumed 100 for this purpofe ; fo that the fums in the 
adjoining columns exprefs the number of chances in 100 
which are in favour of B or A’s furviving the other. 
* Lemma 2. p. IOO. 
Table, 
