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II. " On the Construction of Life-Tables ; illustrated by a New 

 Life-Table of the Healthy Districts of England." By 

 WILLIAM FARR, M.D., F.R.S., Superintendent of the Sta- 

 tistical Department, General Register-Office. Received 

 March 17, 1859. 



(Abstract.) 



The Transactions of the Royal Society contain the first Life-Table : 

 it was constructed by Halley, who discovered its remarkable proper- 

 ties, and illustrated some of its applications. 



With better data improved methods have been found out, and the 

 form has been extended so as to facilitate the solution of various 

 questions. 



In deducing the English Life-Tables from the National Returns, I 

 have had occasion to try various methods of construction ; and I now 

 propose to describe briefly the nature of the Life-Table, to lay down 

 a simple method of construction, to describe an extension of its form, 

 and to illustrate this by a new Table representing the vitality of the 

 healthiest part of the population of England. 



The Life-Table is an instrument of investigation ; it may be called 

 a biometer, for it gives the exact measure of the duration of life under 

 given circumstances. Such a Table has to be constructed for each 

 district and for each profession, to determine their degrees of salu- 

 brity. To multiply these constructions, then, it is necessary to lay 

 down rules, which, while they involve a minimum amount of arith- 

 metical labour, will yield results as correct as can be obtained in the 

 present state of our observations. 



A Life-Table represents a generation of men passing through time ; 

 and tii ^ under this aspect, dating from birth, is called age. In the 

 first column of a Life-Table age is expressed in years, commencing 

 at (birth), and proceeding to 100 or to 110 years, the extreme 

 limit of observed lifetime. Annexed is an outline of the two primary 

 series of the Life-Table, representing the surviving at each year of 

 age (Ig), and the first differences representing the dying (d x )> in annual 

 intervals of age. 



