(JOO PHILOSOPHICAL TKANSACTIONS, [aNNO 1755. 



grees of mortality ; and then by proportion, increasing the numbers of the 

 living corresponding to all ages below 25 ; so that the table, altered in this 

 manner, is the same with Mr. Smart's above that age. And it must be con- 

 fessed, that this correction is very proper, and worthy of its author. But still 

 the table is greatly defective, as he has made no allowances for the recess of 

 great numbers who, after they have been a number of years in town, leave it, 

 if they survive ; and of many others who, after the age of 50, retire from busi- 

 ness into the country. And which is so very obvious, that our burials are fewer 

 than by proportion they ought to be after 50 years of age, as mentioned above, 

 and by consequence the people appear more healthy after that age ; so that after 

 70 they seem more healthy than at Breslau. For at 75 there appears from this 

 table to die 4 out of 45, whereas at Breslau there die 10 out of 88. 



And that a great number retire from the town, after the age of 50, or before, 

 is further evident, if we suppose, even according to this corrected table, that 

 one in 25 die at the age of 50. For then the number of people alive, between 

 40 and 50, will be greater than 2604 multiplied by 25, or 65100: which ought 

 to be exhausted by all the deaths in the subsequent period. But all the deaths 

 which ought to arise from that number of living, in the following years to go, 

 according to the bills in the 3d column, is 5315 multiplied by jO, or 53150; 

 which is less than the people that were alive between 40 and 50, by 1 1950, or 

 rpore. And therefore above 1 1000, of those between 40 and 50, must have re- 

 tired from town. : 1; .K' J 

 h,.3ut now, as our bills are defective, it is next to be considered, what we at 

 London are to do at present, and what method of computation we are to follow? 

 And Dr. B. imagines it is very obvious what may be done. Our bills may be used 

 so far as 14 or 20 years ; for there is certainly no increase of our people till the 

 age of 14; because few young people come to town till they are fit to be appren- 

 tices or servants. And between 14 and 20, though many come at that time, 

 yet there is an emigration of a great number from hence to sea, to other coun- 

 tries, the universities, and country academies, that nearly balances the accession 

 of strangers. And then, after 20 years of age, the Breslau bills will be suffi- 

 ciently correct, to show the probability of life within and about the city. And 

 if so, a table may be made from both bills, that will agree with our case here 

 with sufficient exactness. For he cannot find that there is any difference in 

 the bills, above the age of 20, that can be depended on. 



And from all considerations, he thinks it may be allowed, till it is otherwise 

 demonstrated, by bills formed in a different manner from what they are at pre- 

 sent, that the probabilities of life are much the same at London as at Breslau, at 

 the age of 20 or after 14. And if we take this for granted, we shall from thence 

 be able to form a useful table, for those within our bills, by accommodating and 



