For the same
purpose, a light, but sufficient fender of brass wire, say 0.03 inch
diameter, might be judiciously placed around the brass tube at a little
distance, to protect it and the thermometer inside of it from shocks
from the platinum ball when hastily thrown in, as it must always be.
I have had delicate and costly thermometers broken for want of such a
fender. Thermometers cannot be too nice for this work. For accurate work
at moderate temperatures, they should be about 14 inches long, having a
"safe" bulb at the upper end, with a range of 20 deg. F.--32 deg. to 52 deg.--in a
length of 10 inches, giving half an inch to a degree F., and carefully
graduated to tenths of a degree, so that they can be read to hundredths,
corresponding to single degrees of the heat-carrier in the normal use of
the instrument.
For the determination of the highest temperatures, up closely to 2,900 deg.
F., it will be convenient to have thermometers of greater range, say 32 deg.
to 82 deg. F., 50 deg. in a length of 12.5 inches, or a quarter of an inch to
a degree F., also graduated to tenths, or at the least, to fifths of a
degree. Such thermometers will be about 17 inches long.
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