66 



Mr W. Frascr on the Hislory and Constitutmi of' 



TABLE of EXPECTATION of LIFE, at and after the Aye of 20 Years, 

 according to the Northampton and Carlisle Tables of Mortality ; as also, accord^ 

 iny to the Table (p. 76), dcdticed by Mr John Lyon, for the Hiyhland Society 

 of Scotla?id, from a medium of the Nortliampton, Carlisle, and Swedish Tables, 

 — according to that constructed by Mr Griffith Davies, from the experience 

 of tJie Equitable Society of London, — and according to the rate of Male and Fe- 

 male Mortality found by Mr John Finlaison to have prevailed among the 

 Government Annuitants for the last 45 years. 



The Expectation or Mean Duration of life is the number of years which a body of people, 

 taking them one with another, may be considered as sure of enjoying,— those who live or 

 survive beyond that period enjoying as much more time, in proportion to their number, 

 as those who fall short of it enjoy less ; — or the portion of future existence which an indi- 

 vidual at any age may reasonably expect to enjoy. This •' expectation of life " is found by 

 dividing the total years by the number alive at the age whose expectation is required, do- 

 <lucting half unity or .30 from the quotient, on account of the chance being equal, whether 

 a person shall die in the beginning or end of the year. Thus, in the Table of Mortality, 

 (p. 7<>), .34,8JJ5 is the sum of the second column, at and after 25 years of age, and m5 

 the number living at that age; therefore, 34,895 being divided by 965, tlie quotient will be 

 36.16, and the half of 1, or .50, being subtracted ffom this latter number, it will leave 

 35.66, which is the expectation of life, according to the Highland Society's Table of Mor- 

 tality, of a person aged 25. 



The Probability of Life, or the chance of a person living from one a^e to another, is found 

 by dividing the number living at the latter age by the number living at the former age, 

 according to any table of mortality which may be adopted. 



Hence the Value of an Aimuity, commencing at any given age, or a Sum payable at Death, 

 obviously depends upon the number of years which, accorduig to such expectation and pro- 

 bability, a person of any age has to live. 



