ON THE EFFECT OF COAL FIKES ON THE EYES. 389 



to those districts, in which the mineral is not used ; and, notwithstand- 

 ing the numbers of persons, continually pouring into the coal districts, 

 from other parts of the country, in consequence of the demand for 

 labour, yet the prevalency in the former of the dark eye, especially 

 among the children, is so evident, that whoever will take the trouble 

 to make the observation will most assuredly acknowledge the accuracy 

 of this statement. In what way the sulphuretted hydrogen, &c tj occa- 

 sioned by the coal fires, affects the pigment of the iris> it is not now my 

 intention to inquire. I consider it sufficient, for my present purpose, 

 to establish the connexion between the use of coal, and the dark 

 colour of the eye ; though, from repeated observations, I feel assured, 

 that there are more curious facts connected with the subject than have 

 yet come under the notice of physiologists ; and which, when properly 

 developed, will considerably alter the bearing of many opinions hitherto 

 entertained. 



But as a system so new and unlooked for, cannot be expected to be 

 received without proof, I shall state such facts as I trust will be suffi- 

 cient to place the matter beyond all reasonable doubt. And as the 

 principality of Wales affords a great variety of the different characters 

 alluded to, I shall therefore commence with that portion of the island. 

 And, though writers upon this subject have generally referred to the 

 colour of the hair, yet I must state my opinion, that it is by no means so 

 steady and decided a characteristic as that of the eye. The hair is 

 continually changing its hue, even in individuals ; for what in the 

 child is yellow, becomes in a few years, brown, and at maturity, not 

 unfrequently black ; but the colour of the eye is much more fixed and 

 unchangeable, usually assuming its character of hue at a very early 

 period of infancy, and retaining it, without any great variation, to an 

 advanced age. Besides, the light eye is accompanied by every shade of 

 hair, whether red, yellow, or black, and the colour of the eye is appa- 

 rently less influenced by those external causes, which sooner or later 

 must succeed in changing the general physiological character. And 

 while I am describing the several districts, upon which I have made 

 observation I must state, that in grown up persons I have generally 

 found the hair to have, more or less, a shade of brown : and though 

 black, is not uncommon, and red sometimes seen, yet the people of 

 Britain are, in the aggregate, a brown-haired race. 



But to proceed with this physiognomical survey. Almost the whole of 

 North Wales, and a considerable portion of South Wales, are occupied 

 by a light or blue-eyed people. This feature is so obvious, that Dr. 



