838 
DE. EAEE ON THE CONSTEIJCTION OE LIFE-TABLES. 
Page 
860 
V. THE THEEEFOLD LIFE-TABLE; (1) PEESONS, (2) iMALES, (3) FEMALES ... 
Yi. USEFUL foemulh: 
860—861 
VII. LIFE-TABLE OP THE HEALTHIEST ENGLISH DISTEICTS 
(fl) General description of tlie districts 
(b) Conclusion 
Note on the Two Hypotheses 
862—863 
862— 863 
863— 861 
867—868 
TABLES 
Table A.— Healthy districts; population, 1851; deaths in the five years 1849 to 1853 ; rate 
of mortality at different ages 
Table B. The values of the radical numbers and logarithms on which the two Life-Tables 
for males and females were founded 
Table B1.— Logarithms of h, stereoglyphed by the calculating machine 
Table 0.— Life-Table ; Persons, Males and Females, the Uving and dying at each age, or h 
and dx 
Table D.— Life-Table. Persons 
Table E. — Life-Table. Males 
Table F. — Life-Table. Females ••••• 
— The three Tables, each containing the columns d^, lx, L^., P^, Qj;, constitute the 
three-fold Life-Table. 
Table G. — Tables of mean after lifetime (expectations of life) 
yVb^e.— The Tables were calculated in duplicate, and compared by Mr. F. J. Williams, 
Assistant Senior Clerk, and Mr. J. Lewis, Junior Clerk in the Statistical Department 
of the General Eegister Office. The logarithms of h were compared and found to agree 
with those produced by the machine. 
86Ir— 865 
866 
869 
870—871 
872—873 
874—875 
8 / 6 — “S i i 
878 
The Transactions of the Hoyal Society contain the first Life-Table. It was constructed 
by Halley, who discovered its remarkable properties, and illustrated some of its appli- 
cations. The Breslau observations did not supply Halley with the data to frame an 
accurate Table, for reasons which will be immediately apparent ; but the conception is 
full of ingenuity, and the form is one of the great inventions which adorn the annals ot 
the Koyal Society. 
Tables have since been made correctly representing the vitality of certain classes of 
the population; and the form has been extended so as to facilitate the solution ot 
various questions. 
In deducing the English Life-Tables from the National Keturns, I have had occasion 
to try various methods of construction ; and I now propose to describe briefly the rratrrre 
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 tire healthiest 
part of the population of England. 
The Life-Table is an instrument of investigation ; it may be called a hiometer, for it 
gives the exact measure of the duration of life under given circumstances. Such a Table 
has to be corrstructed for each district and for each profession, to detenrrine their degrees 
of salubrity. To multiply these constructions, then, it is necessary to lay dowrr rules, 
