-----|------------|-------------|-------------|-------------|--------
1 | 4 | 5 | 6 | 7 | 8
| | | | |
I | $26,850.00 | $156,000.00 | $105,000.00 | $287,850.00 | $3.19
II | 31,950.00 | 142,770.00 | 97,000.00 | 271,720.00 | 3.02
III | 17,550.00 | 44,250.00 | 97,000.00 | 158,800.00 | 1.78
IV | 18,000.00 | 41,000.00 | 94,000.00 | 153,000.00 | 1.70
V | 27,150.00 | 73,820.00 | 90,000.00 | 190,970.00 | 2.13
VI | 18,300.00 | 123,200.00 | 94,000.00 | 235,500.00 | 2.62
VII | 27,300.00 | 128,820.00 | 90,000.00 | 246,020.00 | 2.74
VIII| 18,600.00 | 104,000.00 | 94,000.00 | 216,600.00 | 2.41
IX | 27,450.00 | 117,420.00 | 90,000.00 | 234,870.00 | 2.62
X | 18,900.00 | 69,300.00 | 90,000.00 | 178,200.00 | 1.98
XI | 27,750.00 | 92,520.00 | 90,000.00 | 210,270.00 | 2.34
XII | 29,100.00 | 87,220.00 | 90,000.00 | 206,320.00 | 2.30
XIII| 38,550.00 | 135,000.00 | 84,000.00 | 257,550.00 | 2.86
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NOTE.--Producer plant fixed charges are included in the cost of
gas and are charged as "heat" in column 5, so they are omitted
from column 4.

CHAPTER XII

PYROMETRY AND PYROMETERS

A knowledge of the fundamental principles of pyrometry, or the
measurement of temperatures, is quite necessary for one engaged
in the heat treatment of steel. It is only by careful measurement
and control of the heating of steel that the full benefit of a
heat-treating operation is secured.

Before the advent of the thermo-couple, methods of temperature
measurement were very crude. The blacksmith depended on his eyes
to tell him when the proper temperature was reached, and of course
the "color" appeared different on light or dark days. "Cherry"
to one man was "orange" to another, and it was therefore almost
impossible to formulate any treatment which could be applied by
several men to secure the same results.

One of the early methods of measuring temperatures was the "iron
ball" method. In this method, an iron ball, to which a wire was
attached, was placed in the furnace and when it had reached the
temperature of the furnace, it was quickly removed by means of
the wire, and suspended in a can containing a known quantity of
water; the volume of water being such that the heat wou