66 A nalyses of Books . 



II. — The Equilihriuni of Population and Sustenarice demon- 

 strated. By Charles Loudon, M. D. Leamington. 



In this pamphlet the author discusses the importance of insisting on 

 the prolongation of the period of lactation as an auxiliary in balancing 

 the population and the means of subsistance. He observes, " at 

 present on the continent the average of children to a marriage is 

 nearly 4'5. Reasoning on the average age of marriage and the 

 population, as given by the last two census, the number in England 

 is also 4*5. If, by prolonging the time of suckling, the average 

 were reduced to 4, it is evident that population would remain 

 stationary, because one half of our numbers die between birth and the 

 24th year ; and the average age of females marrying is very near to 

 that period. In France, the average age of marrying is 26 years ; 

 that of men being 29 and of women 24." Admitting this, and 

 " child-bearing to terminate at 44, the average of time between each 

 child will be 54 months or 4^ years." How long should lactation 

 be prolonged to keep population in check ? '* Admit in each 

 instance the 9 months of gestation, the ten months of lactation, and 

 one-tenth of the remaining 35 months as an equivalent for the 

 present increase of population, and the period will be 13f months. 

 To this, however, must be added an allowance of 6 weeks for the 

 chances of impregnation during the 3 months and the 6 weeks, on 

 the supposition, that in every 3 instances of lactation, impregnation 

 takes place once. Thus, the entire time will be 15 months, or, in 

 other words one-third longer than the present period. This ex- 

 tension of lactation must necessarily increase the 4*5 years between 

 each child approximately to 5, and, consequently, reduce the 4*5 

 children in a family to 4. It has been already seen, that one half of 

 our numbers die under the age of marriage for females ; the result 

 will then be, that there will remain only a representative for father, 

 and a representative for mother on an average in every family in the 

 country." 



The author then proceeds to shew the capability of the United 

 Kingdom for supporting an almost unlimited population. There is 

 one defect in his calculations, however, viz., that they are founded 

 upon assumed data, not upon statistical returns. There cannot be 

 a doubt that the plan proposed would be an important auxiliary in 

 checking population, which, it is only matter of fact to say with 

 Malthus has always a tendency to increase beyond the means of sub- 

 sistence, and can only be checked by moral restraint, that is, by the 

 exercise of common sense, or vice and misery. 



III. — Observations on the present state of Naval Architecture in 

 Great Britain, <^^c. By J. C. Beamish. Cork, 1836. 



The object of this publication is to draw the attention of naval 

 architects to the proper construction of ships with due regard to the 



taken for a French doctor sent by government to inoculate the people with this 

 dreaded plague ; and the tin box, in which he carried his plants, was regarded by 

 them as the case, in which his stock of infection was kept, in readiness to dissemi- 

 nate wherever he went. See Angler in Ireland, vol. i. p. 189. 



