The same remark applies to crape
and embossing rollers.
For the production of heat in confined spaces and difficult position,
the use of an artificial blast of air is becoming an acknowledged
necessity, and the small Roots blowers now made for such purposes, and
driven by power, are coming rapidly into use.
Sometimes a plate is required to be heated to a high temperature in one
confined spot, and, as an example of this, I may take the bluing of the
hands of watches. For this purpose I have made several arrangements,
and perhaps the best is a thin copper plate, bent down at one side to a
right angle. In this angle, underneath, is directed a very fine blowpipe
flame on one spot, and the hands are passed singly over this spot until
the color comes, when they are instantly pushed over the edge. I have
here the arrangement which is generally used for this purpose. For the
bluing of clock hands, a larger and more equally heated surface is
required, and this can be obtained by a small powerful burner without
a blast of air, using a rather thicker plate to equalize the heat.
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