or (d) | 0.9 | 1.0 | 0.9 | 2.3
(a), (b) and (d) | 9.5 | 9.9 | [A] | 9.0
(a), (d), but no (b) | 5.5 | 5.9 | 3.6 | 7.4
(b), (d), but no (a) | 2.5 | 2.4 | [A] | [A]
(d), but no (a) or (b) | 2.2 | 2.2 | 2.0 | 5.2
(a), (b), but no (d) | 1.9 | 3.1 | 1.7 | [A]
(a), but no (b) or (d) | 1.3 | 2.1 | 1.2 | 2.8
(b), but no (a) or (d) | 1.0 | 1.6 | 1.0 | [A]
No (a), (b) or (d) | 0.9 | 1.0 | 0.9 | 2.6
----------------------------------------------------------------
[A] Percentages not given where base is less than 100.

Symbols: (a) deaf brothers, sisters or ancestors; (b) deaf
uncles, aunts, cousins, etc.; (d) deaf husbands or wives.

The striking feature of these percentages is the regularity with
which they increase in proportion as the number of deaf relatives
increases, until among the 242 persons who have (a), (b) and (d)
relatives, 23 or 9.5 per cent also have (c) relatives. A
consanguineous marriage within a family tainted with deafness would
have the same effect as doubling the number of deaf relatives, which
as we have seen greatly increases the percentage having deaf children.

It would seem that the number of the married deaf reported as having
deaf children is much too small, especially since Dr. Fay[89] produces
statistics of 4471 marriages of the deaf of which 300 produced deaf
offspring. Counting only the 3,078 marriages of which information in
regard to offspring was available these figures show an average of a
little less than one such marriage in ten as productive of deaf
offspring. The total number of children of these marriages was 6,782,
of which 588 were deaf. These 3,078 marriages represented 5,199 deaf
married persons as compared with the 31,334 reported in the Twelfth
Census, or about one sixth. Increasing the 300 families who had deaf
children in the same ratio we have 1800 as compared with the 437
reported by the census. But as it was inevitable that Dr. Fay's cases
should be selected somewhat, he has probably collected records of more
than one sixth of all the cases where deaf children were born of deaf
parents. But we can hardly believe that he found three-fourths of such
cases. The true number therefore must be considerably greater than
437, but less than 1800.[90]

[Footnote 89: _Marriages of the Deaf in America_, chap. v.]

[Footnote 90: Of the 17 ch