Causes Of Deaf-mutism
The intermarriage of blood-relations is doubtless one cause. In one
school for the deaf and dumb 25 per cent., in another 20 per cent., and
in others 15 per cent. of the pupils are said to be the off-spring of
marriages between blood-relations.
Davy mentions the following case observed by Meniere:--A married couple,
being cousins, who enjoyed excellent health, had eight children, of whom
four were born de
f mutes, another was idiotic, another died when five
years of age, and two others suffered from absolute deafness, which only
made its appearance later on.
In the Institution at Derby there are three sisters, and also a younger
sister at home, all born deaf and dumb, the parents being own cousins.
On the other hand, there are at the same Institution several children
having deaf and dumb brothers or sisters, where no relationship exists
between the parents, notably one family, in which both parents are
healthy, and in which there are four deaf and dumb children. In the same
county there are other cases of three, four, and even six in a family,
yet there has been no relationship between the parents. In addition to
the born deaf, measles, bronchitis, typhus, scarletina, and other
diseases are the causes of deafness, and consequently dumbness.
Cases are known to have resulted from lightning, fright, boxing on the
ears, and where young children have been allowed to fall on the head,
etc.
Damp houses are said to be a cause of deafness. In Paris among eight
children born in a family, five were born deaf, and these had all been
born in a damp house. The family who had previously lived in the same
house had three children, among whom were two born deaf and dumb. It is
sometimes said that certain unhealthy trades in which the parent or
parents are engaged are responsible for some of these cases, but the
only complete statistics are those of Nassau, the results of which are
as follows:--
Among 27 Pipe-makers 3 deaf mute children,
therefore 1 deaf mute to 9.0
" 146 Stonemasons 4 " " " 36.5
" 186 Brass-founders 5 " " " 37.2
" 106 Potters 2 " " " 53.0
" 590 Carpenters 8 " " " 73.7
" 176 Earthenware-makers 2 " " " 88.0
" 381 Sailors 3 " " " 127.0
" 1,716 Bricklayers 11 " " " 156.0
" 1,309 Smiths 7 " " " 187.0
" 374 Vat-coopers 2 " " " 187.0
" 1,894 Tailors 10 " " " 189.4
" 2,911 Shoemakers 15 " " " 194.0
" 1,614 Joiners 8 " " " 201.7
" 2,006 Vinters 9 " " " 222.8
" 514 Coopers 2 " " " 257.0
" 1,380 Bakers 5 " " " 276.0
" 49,201 Farmers 104 " " " 473.1
" 18,211 Labourers 24 " " " 758.8
Meckel says that in the families of tradespeople, who are constantly
exposed to a damp unhealthy atmosphere or other injurious influences,
deaf-mutism occurs most frequently. Moreover, Meckel has found that
deaf-mutism is more frequently met with in flour-mills than elsewhere.
Among 990 millers in Nassau, there were found eight deaf mutes, or one
deaf mute to 123.7.