230 KEPORT — ]881. 



27. — The chairman of the Committee, Mr. Francis Galton, conti'ibutes 

 to the Appendix to this Report a paper on the range in height, -weight, 

 and strengtli of the different classes at every age. He measures the 

 range, not between the maximum and minimum valufes recorded, which 

 afford no safe basis for comparison, but through an extension of the 

 principle by which the so-called ' probable error ' is ascertained. Thus, 

 he first arranges the cases in the order of their magnitude, then he 

 cuts off a certain fractional portion of them from either end of the series, 

 and measures the difference between the maximum and minimum of the 

 intermediate group. The ranges given are between the upper and the 

 lower tenths and between the upper and the lower fourths, the value of 

 the latter range being identical with twice the ' probable error.' 



28. — Inspector- General Lawson contributes to the Appendix to this 

 Report a valuable paper giving the results of the earlier portion of the 

 observations furnished to the Committee on eyesight. 



29. — The total number of observations of eyesight collected by the 

 Committee has been 2,956 ; many of which, as will be seen by Dr. Law- 

 son's paper, are not considered ti'ustworthy. Sufficient, however, have 

 now been derived from various independent sources to form a fair average. 



30. — This inquiry as to eyesight has led the Committee to consider 

 the very important question of colour-blindness, which has been ascer- 

 tained in Germany and America to affect 1 in 25 of the male population, 

 and which probably exists in this country to a greater extent than is 

 suspected by most people. 



31. — To facilitate the collection of statistics relating to colour-blind- 

 ness, the Committee accepted an offer which a member, Mr. Roberts, 

 was enabled by the kindness of the Norwegian professor, Daae, to make, 

 that he should prepare for publication an English edition of that profes- 

 sor's tests for colour-blindness, as published in Berlin ; also a description 

 of Professor Holmgren's method, with a revised series of the eyesight 

 tests and popular instructions of his own. 



32. — This work has been published in a compact form,' audits applica- 

 tion might even be made a parlour pastime, since it requires no special 

 qualification in the observer, who may indeed be a colour-blind person him- 

 self. The Committee hope that this little book may be widely circulated 

 and freely used. This book of teats is in use at Marlborough College, 

 and Mr. Roberts conti'ibutes to the Appendix of this report an analysis of 

 the observations made on the whole of the boys and masters, 600 in 

 number, at present in the College, by the Rev. T. A. Preston, a gentleman 

 to whom the Committee arc indebted for many valuable contributions to 

 their store of anthropometric observations. 



33. — Mr. Roberts has remarked on this important subject that ' some 

 unnecessary alarm will be felt by travellers if they are led to believe that 

 colour-blindness is as prevalent among engine-drivers as other men of 

 their own class, and that one person in every twenty-five is subject to 

 this defect. As a matter of fact, the severer forms of colour-blindness 

 are quickly eliminated from the railway services, either by the conscious 

 inability of the men to distinguish the signals to which they are daily 

 and almost hourly subjected, or by the minor accidents they fall into, 

 which leads their employers to dismiss them as careless, incompetent, or 

 intemperate servants. It is, however, most desirable that this clumsy and 



' The Detection of Colmir-hlindness and Imperfect Eyesight. By Mr. Charles 

 oberts, F.R.C.S. Published, at .5.t., bj' Mr. P.ogue, ^ St. Martin's Place, W.C. 



