466 
Hereditary Deafness 
gible to persons with a certain amount of special knowledge, and moreover, owing 
to the various errors which may have crept in during the process, gives uncertain 
and misleading information even to them. In answer one must lay stress on the 
extreme importance of bringing the facts relating to the inheritance of rare 
characters such as congenital deafness into line with those relating to common 
ones, such for instance as tallness or shortness of stature. Without such compari- 
sons it is impossible to make real advance towards knowledge of the general laws 
of heredity, so that even an imperfect attempt at making them is better than 
none at all. The results need mislead no one, as every assumption and every 
known source of error is pointed out ; and as statistical methods do not consume 
the material which they use, the same data can be employed over and over again 
to test any new theory which may seem worthy of investigation. 
Material. The material on which this paper is based is derived entirely from 
E. A. Fay's "Marriages of the Deaf in America " (Volta Bureau, Washington, U.S.A., 
1898, pp. vii and 527). The collection of the facts contained in this book was 
undertaken, as a labour of love, by Dr E. A. Fay, the editor of The American 
Annals of the Deaf, the expenses of the investigation being borne by the Volta 
Bureau, which had been endowed, partly for this purpose, by Dr A. Graham Bell. 
How much labour must have been needed in order to obtain this immense and 
valuable mass of data can be realised from the fact that nearly every marriage of 
a deaf person, which had taken place in America and Canada from 1850 to 1894, 
and a large number which took place before that period are here recorded. 
There are in all, included in the book, records of the marriages of 4471 pairs 
of persons, of whom at least one in each pair was known to be of a degree of deaf- 
ness defined on p. 7 of the introduction in the following words : — 
" The term ' deaf,' as used in this monograph, invariably refers to the class of 
persons for whose benefit our ' schools for the deaf are intended — persons so deaf 
from birth, childhood or youth that they cannot be educated in common schools, 
persons who are more frequently but less accurately classed as ' the deaf and 
dumb ' or ' deaf-mutes.' It includes all persons who are recorded in school reports, 
census reports, marriage records, etc., as ' deaf and dumb,' ' deaf-mutes,' ' totally 
deaf,' ' very deaf,' ' deaf,' or ' very hard of hearing,' and all who have attended the 
schools for the deaf. Persons recorded as ' slightly deaf,' ' partially deaf,' ' deaf in 
one ear,' ' deaf in adult life,' ' hard of hearing,' etc., are not included, unless they 
have attended schools for the deaf" 
Pages 138-499 consist of a tabular record of the 4471 marriages, the details 
given concerning each being as follows : — Date of information, date of marriage, 
total number of children, number deaf, number hearing, number unknown whether 
deaf or hearing. After this come the following particulars concerning both the 
husband and the wife ; whether they were deaf or hearing or whether this was 
unknown, the year of birth, the total number of the family in which they came 
(i.e. their brothers and sisters and themselves) ; how many of these were deaf, how 
many hearing, and about how many this was not reported ; whether they had any 
