574 GEOLOGY OF OHIO. 
sists in constructing ovens similar to the ordinary bée-hive, with flues 
in the bottom, and admitting the air into the oven itself through flues 
communicating with the outside. The oven is thus heated on the 
bottom by the passage of the gases burnt in the oven, and a more uni- 
form, complete and rapid operation ensured. 
The interior of the furnace is shaped very like the common round 
oven. Air is admitted through the dampers in the front en each side 
of the door to the flues, where it enters the interior, and when the 
charge is made the door is closed completely, air being adiitted only 
through these openings. 
The bottom of the oven is provided with flues, and is formed of 
fire-brick or tiles resting on the division walls. The gases burnt in 
the furnace pass through the openings at the rear, and descend through 
the flue to the canals under the oven bottom, through which they pass 
back and forth to a vertical flue, and thence to the chimney through a 
horizontal flue. A damper, placed at the exit of the vertical flue, enables 
one oven to be shut off from the chimney at any time without inter- 
fering with the others. By this construction the floor of the oven is 
thoroughly heated, and it is claimed that coke may be made in one-third 
the time that it can be in the common oven, with a yield 10 to 15 per 
cent. greater. In trials made near Darlington, England, for several 
years, the coal yielded 69 per cent., while in the common oven the 
yield was 58 per cent., and a charge requiring 72 hours to be coked in 
the old oven was completely coked in 48 hours. | 
Jones’ Coke Oven. A form of rectangular oven with the bottom 
heated was introduced at Dudley, Staffordshire, England, by Mr. Cox. 
The entire front being open forms the doorway for the discharge 
of the coke, while the coal is charged through the opening in the roof. | 
At the rear an opening is left the full width of the furnace, and closed 
by an iron plate. It is used for affixing the discharging apparatus as de- 
scribed hereafter. At the back of the furnace are two iron pipes or canals, 
communicating with the exterior, and passing through the chimney. 
Each of these is provided with a register on the outside to regulate the 
admission of the air. A canal opens into the rear end of the furnace, 
just below the arch, while another one rises higher and opens into two 
flues in the masonry of the top of the furnace, which pass to the front 
and open into the oven. ‘Two openings in the back of the furnace per- 
* Trans. N. England Inst. Mining Engineers, 1860-61. 
