The position of the prominent parts
will be more altered than that of the less elevated; and the
greater the relief of the medal the more distorted will be its
engraved representation. Mr John Bate, son of Mr Bate, of the
Poultry, has contrived an improved machine, for which he has
taken a patent, in which this source of distortion is remedied.
The head, in the title page of the present volume, is copied from
a medal of Roger Bacon, which forms one of a series of medals of
eminent men, struck at the Royal Mint at Munich, and is the first
of the published productions of this new art.(3*)
The inconvenience which arises from too high a relief in the
medal, or in the bust, might be remedied by some mechanical
contrivance, by which the deviation of the diamond point from the
right line (which it would describe when the tracing point
traverses a plane), would be made proportional not to the
elevation of the corresponding point above the plane of the
medal, but to its elevation above some other parallel plane
removed to a fit distance behind it. Thus busts and statues might
be reduced to any required degree of relief.
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