empts," he adds, "have been
made to introduce the use of sea-coal in these works instead of
charcoal, the former being to be had at an easier rate than the latter;
but hitherto they have proved ineffectual, the workmen finding by
experience that a sea-coal fire, how vehement soever, will not
penetrate the most fixed parts of the ore, and so leaves much of the
metal unmelted"

[6] Phil. Trans. vol. xliv. 305.

[7] Reverberatory, so called because the flame or current of heated
gases from the fuel is caused to be reverberated or reflected down upon
the substance under operation before passing into the chimney. It is
curious that Rovenson, in his Treatise of Metallica of 1613, describes
a reverberatory furnace in which iron was to be smelted by pit-coal,
though it does not appear that he succeeded in perfecting his
invention. Dr. Percy, in his excellent work on Metallurgy, thus
describes a reverberatory furnace:--"It consists essentially of three
parts--a fireplace at one end, a stack or chimney at the other, and a
bed between both on which the matter is heated. The fireplace is
separated from the bed by a low partition wall called the fire-bridge,
and both are covered by an arched roof which rises from the end wall of
the fireplace and gradually dips toward the furthest end of the bed
connected with the stack. On one or both sides of the bed, or at the
end near the stack, may be openings through which the ore spread over
the surface of the bed may be stirred about and exposed to the action
of the air. The matter is heated in such a furnace by flame, and is
kept from contact with the solid fuel. The flame in its course from
the fireplace to the stack is reflected downwards or REVERBERATED on
the matter beneath, whence the name REVERBERATORY furnace."

[8] Mr. TYLOR on Metal Work--Reports on the Paris Exhibition of 1855.
Part II. 182. We are informed by Mr. Reynolds of Coed-du, a grandson
of Richard Reynolds, that "on further trials many difficulties arose.
The bottoms of the furnaces were destroyed by the heat, and the quality
of the iron varied. Still, by a letter dated May, 1767, it appears
there had been sold of iron made in the new way to the value of 247L.
14s. 6d."

[9] Among the other subscribers were the Rev. Mr. Harris, Mr. Jennings,
and Mr. John Wilkinson, an active promoter of the scheme, who gave the
company the benefit of his skill and experience when it was determined
to construct the bridge of i