ON THE EFFECT OF COAL FIRES ON THE E^ES. 391 



various shades, and from Conway to Holywell the iris has an extraordi- 

 nary uniform leaden hue. The dark shade, as I apprehend, being 

 thrown in by the small supply of coal along that coast. 



It ought to be observed here, that in towns where coal fires are used, 

 even in the clay and slate districts, the dark eye is not uncommon, as 

 in the town of Llandovery for instance ; while the people of the sur- 

 rounding country, who burn turf and wood, are universally light-eyed. 



As we leave the principality and pass through Herefordshire, where 

 coal is not commonly used, the eye is uniformly of a light grey, and 

 continues so, with very little modification, towards Worcester and Bir- 

 mingham. But as we approach Wolverhampton, the change to the 

 dark eye is very perceptible, and here we find another coal field. From 

 Shrewsbury to Chester the dark blue eye is very prevalent ; forming an 

 intermediate tint between the black and blue varieties. 



As we quit this coal district and proceed through Staffordshire in a 

 northern direction, the eye resumes its grey character, until we approach 

 the coal of Newcastle-under-Line, where symptoms of the use of that 

 fuel present themselves ; otherwise, the grey character prevails until 

 we approach Manchester, and in the vicinity of that extensive coal 

 field it becomes decidedly dark, and continues so for a considerable way 

 on the road towards Preston ; and in this country I have noticed several 

 instances of an anomalous description, — i. e. of dark eyes, accompanied 

 by light hair. 



As we proceed from Chester towards Manchester, the black eye is 

 very rare, and at Warrington particularly so, and even onwards to the 

 environs of Manchester. What quantity of coal the common people 

 use as fuel I have not ascertained, but on the road side I noticed an 

 extensive turf bog, with its stacks of peat piled up in great quantities ; 

 indicating that a considerable portion of the inhabitants were supplied 

 from thence. And as might be expected, the blue eye prevails in its 

 vicinity. 



On passing Manchester through Stockport, the influence of coal is 

 again very perceptible ; but in the Derbyshire hills, where it is more 

 expensive, and of course more sparingly used, the dark eye declines. 

 On approaching, however, the great central coal field in the neighbour- 

 hood of Matlock, it resumes its character. 



As we skirt the borders of this coal field towards Derby, the blue 

 eye becomes a good deal darkened, and forms a sort of transition from 

 blue to black ; but if we dip into the basin, at Nottingham for instance 

 we find the dark eye appear, and become more and more frequent, so 



