In Norway, according to Uchermann, while 6.9 per cent of all marriages are consanguineous within and including the degree of second cousins, and in single cantons the percentages range as high as 31.0, only in one single district does the number of the deaf-mutes harmonize with that of the marriage of cousins. The district of Saeterdalen has the greatest number of consanguineous marriages (201 out of 1250), but not a single case of deaf-mutism. Hedemarken, which has the fewest consanguineous marriages has a great many deaf-mutes. Where deaf-mutism exists it seems to be intensified by consanguinity, but where it is not hereditary it is not caused by consanguinity. Of the 1841 deaf-mutes in Norway, 919 were congenitally deaf, and of these 212 or 23 per cent were of consanguineous parentage.[86] [Footnote 86: _Les Sourds-muets en Norvège_. Quoted by Feer, _Der Einfluss der Blutsverwandschaft der Eltern auf die Kinder_, p. 22.] Dr. Feer gives a table containing the results of a number of studies of deaf-mutism, which shows an average of 20 per cent as of consanguineous origin. Four investigations give the number of children to a family. Table XXVII from Feer seems to indicate that the Irish census is fairly accurate at this point.[87] [Footnote 87: Feer, op. cit., p. 22.] TABLE XXVII. _Average Number of Children to a Family._ ------------------------------------------------- |Consanguineous|"Crossed" Observer. | marriages. |marriages. ------------------------------------------------- Huth (Irish Census) | 1.68 | 1.17 Wilhelmi | 1.71 | 1.26 Mygind | 1.53 | 1.20 Uchermann | 1.41 | 1.19 ------------------------------------------------- In the American Census the instructions to enumerators have been so diverse that statistics of the deaf have been very poor until recent years. Not until the Twelfth Census was the inquiry put upon a really scientific basis. This reform, as also the more intelligent attitude of the American people in general towards the affliction of deafness, is due largely to the work of Dr. Alexander Graham Bell. An enumeration of Dr. Bell's services directly, and through the agency of the Volta Bureau, in this cause, cannot be given here. For our purpose the most important of his contributions is embodied in the Special Report of the Twelfth Census of the United States already referred to.