------------------------------------------------------------
-------------- Total | 163 | 287 | 1.76| 113 | 191 | 1.69| 276 | 478 | 1.73 No | | | | | | | | | relation- | | | | | | | | | ship[A] |2,842 |3,609 | 1.27|2,474 |3,229 | 1.31|5,316 |6,838 | 1.29 ------------------------------------------------------------
-------------- Grand total |3,005 |3,896 | 1.30|2,587 |3,420 | 1.32|5,592 |7,316 | 1.31 ------------------------------------------------------------
-------------- [A] See Table XXV.

In Scotland Dr. Arthur Mitchell made inquiry of the superintendents of a number of deaf-mute asylums, and found that of 544 deaf-mutes, 28 were the offspring of 24 consanguineous marriages.[85] There were 504 families represented in all, so that the average per family was 1.17 among the consanguineous to 1.07 among the non-consanguineous.

[Footnote 85:  Huth, op. cit., p. 226.]

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 Norvege.  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.