( 6ro ) 
And fo forth to the 6oth year, when we fuppofe the elder 
Life of Forty certainly to he expired ; from whence till Se- 
venty we-muft compute for the Firft and Second only, and 
from thence to Ninety for the fingle youngefl: Life. Then the 
Sum Total of all thefe Fourth Proportiona's being taken out 
of the value of a certain Annuity for 90 Years, being 16,5-8 
years Purchafe, fliall leave the juft value to be paid for an 
Annuity during the whole term of the Lives of three Perfons 
of the Ages propofed. And note, that it will not be nece£ 
fary to compute for every year fingly, but that in mod cafes 
every 4th or f th year may fuffice, interpoling for the inter- 
mediate years fecundum artem. 
It may be objected, that the different Salubrity of places 
does hinder this Propofal from being univerfal j nor can it be 
denied. But by the number that die, being n 74. per Annum 
in 34000, it does appear that about a 30th part die yearly, as 
Sir William Petty has computed for London ; and the number 
that die in Infancy ,is a good Argument that the Air is but in- 
differently falubrious. So that by what I can learn, there can- 
not perhaps be one better place propofed for a Standard. At 
leafl 'tis defiredthat in imitation hereof the Curious in other 
Cities would attempt fbmething of the fame nature, than 
which nothing perhaps can be more ufeful. 
The 
