212 POPULAR SCIENCE MONTHLY. 



the methods of death registration enable ns to form an approximate 

 estimate of the proportion of childless marriages among the whole pop- 

 ulation of somewhat mixed British race, with a high standard of living, 

 we find that the proportion of marriages in which there are no sur- 

 viving children at the father's death is about 16 per cent. With due 

 allowance for the earlier death of the children and for the ignorance, 

 in a certain proportion of cases, of those who filled in the death cer- 

 tificate, it is probable enough that this result is not really larger than 

 the other. In any case there is an excess of sterility among the grouj) 

 of intellectually eminent men, this excess being the more marked when 

 we remember that in very large majority they belong to a period when 

 the artificial restraint of reproduction had scarcely begun to be widely 

 practiced. 



It is somewhat remarkable that, although the number of infertile 

 marriages is so large, the average fertility of those marriages which 

 were not barren is by no means small. We have fairly adequate in- 

 formation in the case of the marriages of 214 of these eminent men. 

 I have not included those cases in which the national biographer is 

 only able to say that there were 'at least' so many children, nor have 

 I knowingly included any cases in which there were two or more mar- 

 riages. Whethe]" the number of children represents gross or net fer- 

 tility, it is, unfortunately, in a very large proportion of instances, 

 quite impossible to say. It is probable that in a large proportion of 

 cases only the net fertility, i. e., the number of children who sur- 

 vived infancy and childhood, has been recorded. It is, therefore, the 

 more remarkable that the average number of children in these 214 

 fertile families is 5.45. Thus, although our data are probably imper- 

 fect, they show that the fertile marriages of British men of genius have 

 produced families which contain on the average one child more than 

 the fertile marriages of ordinary people of the same race during the 

 nineteenth century; in New Zealand the average number of chil- 

 dren left by fathers of families (whether as the result of one or 

 more marriages) dying between the ages of twenty-five and sixty-five, 

 is 4.81, which indicates a much larger gross fertility. It must, 

 of course, be remembered, on the other hand, that the emi- 

 nent men in our group lived to a very high average age, and it is 

 obvious that .men who live to an advanced age will have a better 

 chance of leaving large families than those who die young.* This 

 consideration somewhat diminishes our estimate of the fertility shown 

 by British men of genius, while, if we take barren marriages into 



* Even apart from this, tliere appears to be a connection between longevity 

 and fecundity; see M. Beeton and Karl Pearson, 'On the Correlation between 

 Duration of Life and the Number of Oflfspring,' a paper presented to the Royal 

 Society of London^ June 14.. 1000. 



