This made a
tight fit on the outside of the barrel, and as it was nearly an inch deep,
I expected that if it were driven home on the barrel and soldered to it the
joint would be too near the water chamber to be affected by the lamp. This
has proved to be the case, even when the water is nearly at boiling point.
If a very close-fitting box is not procurable, the space between box and
barrel must be filled in with a strip of tin cut off to the correct length.
The Lamp Chamber.--Cut out a strip of tin 4 inches wide and 1 inch longer
than the circumference of the lower end of the hot-air chamber. Scratch a
line 1/2 inch from one of the sides, a line 3/4 inch from the other, and a
line 1/2 inch from each of the ends.
A lamp hole is cut in the centre, and ventilation holes 1 inch apart, as
shown in Fig. 103. If the latter holes are made square or triangular (base
uppermost), and the metal is cut with a cold chisel so as to leave the side
nearest the edge unsevered, the parts may be turned up to form supports for
the barrel.
[Illustration: FIG. 103.--Plate for lamp chamber cut out ready for
bending.
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