APPENDIX Z. 



The following table, combining all the cases of marriage recorded in Tables A to J, was sub- 

 mitted to Prof. Simon Newcomb for his opinion regarding the number of congenital deaf-mutes 

 who had married congenital deaf-mutes. The Reports of the American Asylum and Illinois Insti- 

 tution give no information bearing on this point ; but it seemed possible to determine the proba- 

 bilities from the data given in the table, especially as the intermarriages, in a large proportion of 

 cases, undoubtedly occurred between deaf-mutes who had been educated in the same Institution, 

 and who were therefore both included in the table : 



The main question proposed was this : Of the congenital deaf-mutes who are recorded to have 

 married deaf-mutes, what proijortion have married congenital deaf-mutes? 



Professor Newcomb has been kind enough to send the following letters in reply to the query: 



Nautical Almanac Oifice, Navy Department, 



Washington, D. C, May 20, 1884. 

 Dear Mr. Bell: Although the (xuestiou you ask, seems to admit of a satisfactory answer, I notice a singular 

 defect in the statistical table. It contains not a single case of a deaf-mute being reported as having married a hearing 

 person. If this is an accidental omission in making the copy for you it ought to be corrected. If there is really no 

 such record the case is very singular." It would look as if the parties were ashamed to state that they had married 

 hearing persons, or the recorders had rejected all such cases. 



The main «[uestion you ask can, I think, be answered by the theory of probabilities. Your table, if I understand 

 it correctly, shows that out of 629 persons in the institution (of whom 329 were males and 300 females) a little less 

 thau one-half (298) were congenital deaf-mutes. Now, I see no reason for supposing that the persons whom they 

 married would be divided in any essentially dififerent proportion between the two classes. 



It is true that could we learn from the census tables how the entire deaf of the country of marriageable ages, say, 

 between the ages of twentj' and thirty, are divided between the two classes, our conclusions might be modified. If, 

 for example, it should be found that of the total number of deaf alluded to only one-third were congenital cases, we 



* Only eleven deaf-mutes were specifically stated to have married hearing persons, and 151 were recorded 



simply as " married." 



261 



