four in a
family, 19.0 per cent; more than four in a family, 21.1 per cent.

TABLE XXV.
_Number of Congenital Deaf mutes to a Family in Ireland._
----------------------------------------------------------------
| | Families in which deaf-mutes numbered.
| |----------------------------------------
Year.| Parentage. | 1. | 2. | 3. |4.|5.|6.|7.|8.|9.|10.|11.
----------------------------------------------------------------
1851 | Parents cousins | 127| 45 | 20 |10| 5| 2|..| 1|..|.. |..
1871 | Parents cousins | 91| 38 | 24 | 5| 3| 1| 1|..|..|.. |..
1881 | Parents cousins | 63| 30 | 13 | 6| 1|..|..|..|..|.. |..
1891 | Parents cousins | 82| 38 | 19 | 9| 1| 3| 1| 2|..|.. |..
1901 | Parents cousins | 79| 34 | 23 | 7| 1|..| 1|..|..|.. |..
1851 | All families[A] |2963|347 |158 |35|13| 5|..| 1|..|.. |..
1871 | All families[A] |2460|305 |167 |47|20| 5| 1|..|..|.. |..
1881 | All families[A] |2080|281 |162 |39|18| 6|..|..|..| 1 |..
1891 | All families[A] |1473|273 |134 |40|12| 6| 1| 2|..|.. | 1
1901 | All families[A] |1219|231 |122 |34|10| 4| 2|..|..|.. |..
----------------------------------------------------------------
[A] Number of the "Deaf and Dumb" to a family, "as far as
could be ascertained."

In 1871 and 1881 the inquiry was more minute and the degrees of
consanguinity were specified. Mr. Huth quotes some of the figures for
these years, probably derived from the same sources as Table XXVI, and
comments as follows: "An examination of this table will show that the
statistics so much relied upon as proving the causation of deaf-mutism
by consanguineous marriages show nothing of the sort. In 1871 fourth
cousins produced more deaf-mutes per marriage than any nearer
relationship. In 1881 third cousins produced more than any nearer
relationship."[83] Mr. Huth forgets that he is basing these statements
on five and nine families respectively, and does not take into
consideration the probability that if the returns are biased, as he
suspects, this bias would affect the more distantly related,
relatively more than the first cousin marriages, for the same reason
that this would be true of the cases collected by Dr. Bemiss.[84]
Combining the figures of the two censal years helps to correct these
averages, and the distantly related show approximately the same
average as the first cousin marriages in spite of the vastly greater
selection which must have ob