ideal mid-parent whose qualities are what are really inherited. He finds a constantly operative law of regression toward mediocrity, and shows that gifts of high order are little likely to be transmitted fully. "The more bountifully a parent is gifted by nature, the more rare will be his good fortune if he begets a son who is as richly endowed as himself, and still more so if he has a son endowed still more largely." But the law is even-handed, and the son no more inherits all his father's wickedness and disease than he does his good points. In this study, the heredity of stature, eye, color, artistic taste, disease, and the matter of latent characters, are discussed. The material used is interesting. What was needed was the facts regarding several succeeding generations, each containing a considerable number of individuals equally related to each other (fraternities, etc.); groups, not individuals. Mr. Galton offered a considerable sum in prizes for family records, which were used as the basis of these studies. Some material was also secured at his Anthropometric Laboratory. But human material, sufficient in quantity and precise in character, is very difficult to obtain; and to secure fraternities of the desired size and representative of several generations, Mr. Galton directed careful cultures of sweet peas and "pedigree moths." He concludes that every individual receives from each parent one-fourth of his endowment and from each grandparent one-sixteenth. As a final conclusion, he says: "Suppose two couples, one consisting of two gifted members of a poor stock and the other of two ordinary members of a gifted stock. The difference between them will display itself in their offspring. The children of the former will tend to regress; those of the latter will not." Here again we see his plan for amelioration.
We have referred above to Mr. Galton's Anthropometric Laboratory. It is known to most visitors to the South Kensington Museum. In it anyone may be thoroughly examined and measured free of charge; a permanent record is made of his measurements and faculties, and a copy is given to him for his own use. For use in this Laboratory, Mr. Galton has devised some most ingenious pieces of apparatus for the study of delicacy in hearing, quickness of blow, keenness of eyesight, etc. In devising such instruments and pieces of apparatus for clearly illustrating points of considerable mathematical complexity, Mr. Galton is a veritable genius. He is also the inventor of composite photography, which has been used in so many ways in science. For some years past those who were measured in the Laboratory have left the impression of their finger-tips behind them, and a study of this material has led to his last book, "Finger-Prints."
As in all his writing, Mr. Galton presents first a summary of the treatment to be pursued in the book. Finger-prints have been used among various peoples in signing legal papers, but have seldom been used for purposes of identification. Sir William Herschel made such use of them in India. A full statement of the methods of taking finger-prints, of enlarging them, and of study, are then given. Anyone who will look at his own finger-tips will see that they are covered with curved ridges surrounding a central core; this core may be either an arch, a loop, or a whorl. Taking into consideration the ridges above and below these cores, and the cores themselves, some nine fundamental patterns may be made out. These may serve as a basis for classification. In any given pattern there are also minor details which characterize it. But confining attention to only the more important points, one may easily and exactly describe any given combination. Mr. Galton thinks that he finds, from careful study of a considerable number of cases, that the patterns are persistent from birth to death. If this is so, and it is likely that finger-prints of two persons are never identical, we have here, of course, an important means for identification. After finding how many points of comparison are presented in a single finger-print, Mr. Galton calculates the mathematical probability of any two persons having the print made by any single finger identical, at 1:2³⁶, or 1 to 6400 millions. "It is a smaller chance than 1 to 4 that the print of any single finger of any given person would be exactly like that of the same finger of any other member of the human race." What would the probability of identity be if all ten finger-prints of one man were compared with all ten of those of another? Everyone knows how important a rapid, simple, and certain means of identification is to-day. Bertillon's method of measurement met the demand so well that it has rapidly been adopted in reformatories and prisons, but it is by no means certain. It is true that a man who can make Bertillon's measurements is more readily found than one who can compare finger-prints; but two minutes' time would add a card of finger-prints to the anthropometric data secured in
