VOL. XLIX.] PHILOSOPHICAL TRANSACTIONS. 699 



increases, till after the age of 40 ; when the number of the dead continues nearly 

 the same, though the probability of life continually decreases till the age of 80 ; 

 and then at length, the living being almost all exhausted, the burials are greatly 

 diminished, AU which seems to be agreeable to the course of nature ; but con 

 trary to what we see in the London bills, especially after 50 years of age. How- 

 ever, they both agree in thi?, that the most healthy age is between 10 and 20, 

 and the infant state under 5 years of age the most uncertain for life. 



Indeed it must be acknowledged, that in computing the Breslau table. Dr. 

 Halley had great advantages, which have made it so perfect. He had the num- 

 ber of births given, besides the burials at the different ages, in an inland town, 

 where there is no great concourse of strangers. But with us at London, the 

 number of births is not known ; because of the number of Dissenters of various 

 denominations, both foreigners and natives, of whose baptisms there is no ac- 

 count taken ; which makes our bills at psesent very imperfect. For none are 

 put into our bills but those wiio are baptized according to the form of our esta- 

 blished church. And therefore there are some thousands omitted, and yet many, 

 perhaps the one- half of them, ^vho are not baptized with us, bury with us; which 

 greatly perplexes our bills. And under this disadvantage it appears very difficult to 

 make an accurate computation of the decrements of life through the different 

 ages ; though this defect he imagines he shall be able nearly to supply. floulw 

 -')-iThere have indeed been some ingenious men who have thouight, that our 

 London bills are correct enough to form a table from them, which may better 

 agree with our circumstances than that which Dr. Halley has given us. And 

 Mr. Smart was the first who endeavoured to do something in this way, from our 

 bills only, about 18 years ago. But, in the table made by him, he seems to 

 have been greatly mistaken ; for he has made no allowance for the accession of 

 strangers, but considered the numbers of the dead, in all the periods of life, as 

 all come from those born here ; whereas it is evident that the strangers, above 

 20 years of age, are at least equal to them. And this has brought this paradox 

 into his table, that young people between 12 and 18, at London, are much 

 more healthy than at Breslau, or in any country place in England. For accord- 

 ing to him, in the 13th year, 2 die only out of 479 5 but at Breslau there die 6 

 out of 634; that is, there is double the number die more at Breslau than at 

 London ; which appears impossible. But between 30 and 40, he makes them 

 much more unhealthy than they are ; for at 40 he supposes one to die in 29 ; 

 whereas there does not die above one in 30, all ages taken together, with infants 

 included. Another ingenious gentleman, having seen this inconsistency, has 

 endeavoured to correct it, by supposing that the number of strangers that come 

 to settle in town, after 25 years of age, is inconsiderable ; and that above that 

 age, the numbers of burials may be considered, as arising from the natural de- 



