95 
present ; although it will not probably long remain so, as 
the immense formation of iron ores is now being fast 
developed, and smelting works in the course of erection. 
The amount of money turned over in jet at "WTiitby is 
over £20,000 annually. The population is about 14,000, — 
800 to 1,000 of whom are employed in the manufacture 
of jet ornaments. 
13 and 17. Pecten and Avicula Ironstone. — Those two 
important measures of argillaceous or clay band ironstone, 
together nine to ten feet in thickness, are of excellent quality, 
and have been extensively worked for upwards of 20 years, and 
sent to the Tyne for smelting. Now that we have got direct 
Railway communication to the Durham Coke Fields, and an 
immense limestone formation close at hand, preparations are 
making on a large scale to convert the ores into iron on 
the place where risen ; and the day is not far distant when 
this locality will rival, if not excel, the Cleveland district 
— this district having the advantage of a variety of ores for 
mixing, so essential to the production of good iron. 
From calculations made by practical men, (iron masters), 
good pig iron can be produced for from 45s. to 47s. per ton 
in the Esk valley. Those measures of ironstone, geologically, 
are the same as the Cleveland ores, although the latter is in 
one seam, and partaking more of our Oolitic seams. However, 
they can be traced along the Cliff from one place to the 
other, shewing distinctly where the seams begin to separate at 
Kettleness Beach. The difference in appearance is probably 
from our stone laying at a greater depth, and subject to a 
greater pressure. _ I observe that S. H. Blackwell, Esq., in 
his little work on the Iron Making Resources of the United 
Kingdom, represents the Cleveland seam as the Oolitic or 
Northampton ore, and refers to Eston mines, and the 
Whitby, under the class of argillaceous ironstone of the 
lias. But in this Mr. Blackwell is not correct, for they are 
one and the same seams, geologically speaking, with the 
