744, REPORT—1863. 
18 feet, after which it splits again into bands, and, as far as is known, resumes. 
towards the east and south the character formerly observed as attaching to it 
at Grosmont, near Whitby. 
From the details just given it will be seen that, although the quantity of 
ironstone in the Main Cleveland Seam is practically inexhaustible, the portion 
which, in recent years, has yielded such immense quantities of rich mineral, 
as far as we can at present judge, occupies comparatively a very limited area. 
Commencing at Swainby, near Osmotherley, which is the most western point 
where the bed is worked, its thickness is not much above 3 feet, and the per- 
centage of iron under 28. It improves gradually in a north-eastern direction 
past Kildale, where a working was attempted, and abandoned, by the writer’s 
firm. Itis not until we reach Codhill, thirteen miles from Osmotherley, that 
the seam is considered worth extracting; and a line from this point to Rock- 
cliffe, on the coast, a distance of twelve miles, will probably be found as forming 
the southern boundary of the best stone; so that, after making the necessary 
allowance for denudation, twenty to thirty square miles may be assumed as 
the extent of the area, of which a considerable portion lies at a great depth. 
Much more irregular in its features is the so-called Top Seam. At Nor- 
manby and Eston little more than its position can be recognized, and through- 
out the entire field it varies from afew inches to many feet in thickness. In 
richness of iron it is not less changeable, giving from 20 to 35 per cent. of 
metal, according to the locality from which the sample may be taken. In 
the Main seam there exists a certain degree of uniformity, even in the change 
of thickness and richness; but in the Top seam both alternate very frequently 
in a most unlooked-for manner. On the western side of the district Ingleby 
Greenhow is the most northern, and indeed the only place where the Top seam 
has been wrought in that direction. In the mine there its thickness was 2 
feet, and its richness in iron 34°75 per cent. On the other side of the valley 
it thinned away to a few inches, containing 37-65 per cent. of metal. Near 
Osmotherley the seam is several feet thick, and in it a few inches at the top 
contain 41 per cent. of iron; these are succeeded by 3 feet of stone, with 24-5 
per cent., lying upon the top of 10 feet, giving 16-70 per cent. of iron. On 
the east coast, at Port Mulgrave, Messrs. Palmer formerly worked a small 
district of the Top seam 4 to 43 feet thick, which on analysis gave 30°99 per 
cent. of iron. In Goadland Dale, Glazedale, Fryup Dale, and Danby Dale 
this seam varies from 5 feet to 8 or 9 feet in thickness, and yields from 20 to 
25 per cent. of iron. In one case it is as low as 9°33, and in another case as 
high as 30°11 per cent., but both of these results were from a very limited 
area. Unless the magnetic ironstone worked at Rosedale Abbey is a portion 
of this Top'seam, about which some doubt has been expressed, all the work- 
ings in connexion with this bed have been abandoned from the causes just 
enumerated. 
A word or two respecting the mode of extracting the ironstone from the 
Main Cleveland Seam in the northern portion of the field,7.¢. near Middlesbro’, 
will probably not be considered as altogether superfluous. There is a portion 
of the bed at the top 3 feet thick, over and above the heights of the seam 
formerly given, and separated by a parting from the remainder of the bed, 
which parting varies from being a mere point of separation to a thickness of* 
6 or 7inches. When it attains this latter thickness, or even less, its contents 
are so impregnated with bisulphide of iron as to give 28 per cent. of sulphur. 
This band, being} easily detached from the ironstone, was applied in the 
chemical works at Washington as a substitute for ordinary pyrites, and con- 
tinued to be so used until a manufactory at Middlesbro’ was able to consume 
