CLAY DEPOSITS. 663 
The Lower Mercer horizon furnishes but a small amount of clay at 
present to the manufacturing establishments; at the Springfield clay 
banks the limestone clay cannot be distinguished from the potters’ clay 
by eye, but all potters carefully avoid it. Another development of the 
Mercer clay in south-west Hocking county, on the contrary, shows a 
very fine potters’ clay, and it forms the basis of a large neighborhood 
manufacture of stone-ware. ‘The locality is peculiarly inaccessible, and 
its processes are correspondingly primitive. ‘The locality referred to is 
the Potters’ Ridge of Hocking and Vinton counties. At the brick 
works of Wagner, Wentz & Co., three miles north of Dover, Tuscarawas 
county, on the C. L. & W. R. R., the clay of the Lower Mercer coal is 
quite largely used as a bond clay and for third class fire-brick. It lies 
under 6 feet of fine blue limestone and 18 inches of coal, in a bed from 12 
to 16 feet thick; it is too hard to pick by hand, but is readily plastic 
under treatment. It is mined by drifting, and only about 8 feet are 
taken. There are many places where clay of this character could be 
found at this horizon, but without the presence of hard clay near by it 
is not particularly valuable. 
The Upper Mercer horizon is still less serviceable. At Hayden- 
ville, Hocking county, there is a fine deposit of silicious clay, which 
belongs probably to the Upper Mercer level. A blue limestone is found 
ten feet below, and a coal streak parts it into two strata. Above it 
comes the regular vein of Upper Mercer coal 24 inches thick. There 
is a large establishment in process of erection at this point for manufac- 
turing sewer-pipe, for which purpose the clay seems eminently fitted. 
This is the only development near by, or in other parts of the State of 
this horizon in which the clay figures. 
The Tionesta clay finds but little use in any Ace ct the only well- 
known instance being at Calumet, Jefferson county, where it furnishes 
material for a large sewer-pipe and brick industry. It was at first ex- 
pected to make the Lower Kittanning clay the basis of manufacture. The 
shaft by which this clay was reached was continued down 100 feet 
further without definite purpose, when a bed of clay 12 feet thick was 
struck. It is overlain by shales, and occasionally an inch or so of coal, 
and it runs sometimes to the great thickness of 18 feet. The system of 
mining here is better defined than in any other part of the State. The 
entries are driven in straight lines, the rooms turned off at regular 
intervals and at right angles to the entries. Entries and rooms are 
