[128] Even Dr. Newsholme, usually so cautious and reliable an investigator in this field, has been betrayed into a reference in this connection (_The Declining Birth-rate_, 1911, p. 41) to the "increasing rarity of altruism," though in almost the next paragraph he points out that the large families of the past were connected with the fact that the child was a profitable asset, and could be sent to work when little more than an infant. The "altruism" which results in crushing the minds and bodies of others in order to increase one's own earnings is not an "altruism" which we need desire to perpetuate. The beneficial effect of legislation against child-labour in reducing an unduly high birth-rate has often been pointed out. [129] It may suffice to take a single point. Large families involve the birth of children at very short intervals. It has been clearly shown by Dr. R.J. Ewart ("The Influence of Parental Age on Offspring," _Eugenics Review_, October, 1911) that children born at an interval of less than two years after the birth of the previous child, remain, even when they have reached their sixth year, three inches shorter and three pounds lighter than first-born children. [130] For instance, Goldscheid, in _Hoeherentwicklung und Menschenoekonomie_; it is also, on the whole, the conclusion of Newsholme, though expressed in an exceedingly temperate manner, in his _Declining Birth-rate_. [131] If, however, our birth-rate fanatics should hear of the results obtained at the experimental farm at Roseville, California, by Professor Silas Wentworth, who has found that by placing ewes in a field under the power wires of an electric wire company, the average production of lambs is more than doubled, we may anticipate trouble in many hitherto small families. Their predecessors insisted, in the cause of religion and morals, on burning witches; we must not be surprised if our modern fanatics, in the same holy cause, clamour for a law compelling all childless women to live under electric wires. [132] J. Holt Schooling, "The English Marriage Rate," _Fortnightly Review_, June, 1901. [133] G. Udny Yule, "Changes in the Marriage-and Birth-rate in England," _Journal of the Royal Statistical Society_, March, 1906. [134] At an earlier period Hooker had investigated the same subject without coming to any very decisive conclusions ("Correlation of the Marriage-rate with Trade," _Journ. Statistical Soc._, September, 1901). Minor fluctuations in marriage and in trade per head, he found, tend to be in close correspondence, but on the whole trade has risen and the marriage-rate has fallen, probably, Hooker believed, as the result of the gradual deferment of marriage.