the index hand will point to the relative
humidity on scale at bottom of chart (for example see Fig. 94). Should
the temperature indicated by the wet-bulb thermometer be 60 degrees,
and that of the dry-bulb 70 degrees, the index hand will indicate
humidity 55 degrees, when the pointer rests on the intersecting line
of 60 degrees and 80 degrees.

The Recording Hygrometer

In Figure 95 is shown the Recording Hygrometer complete with wet and
dry bulbs, two connecting tubes and two recording pens and special
moistening device for supplying water to the wet bulb.

This equipment is designed particularly for use in connection with dry
rooms and dry kilns and is arranged so that the recording instrument
and the water supply bottle may be installed outside of the dry kiln
or drying room, while the wet and dry bulbs are both installed inside
the room or kiln at the point where it is desired to measure the
humidity. This instrument records on a weekly chart the humidity for
each hour of the day, during the entire week.

[Illustration: Fig. 94. The Hygrodeik.]

The Registering Hygrometer

In Figure 96 is shown the Registering Hygrometer, which consists of
two especially constructed thermometers. The special feature of the
thermometers permits placing the instrument in the dry kiln without
entering the drying room, through a small opening, where it is left
for about 20 minutes.

[Illustration: Fig. 95. The Recording Hygrometer, Complete
with Wet and Dry Bulbs. This instrument records on a weekly
chart the humidity for each hour of the day, during the
entire week.]

The temperature of both the dry and wet bulbs are automatically
recorded, and the outside temperature will not affect the thermometers
when removed from the kiln. From these recorded temperatures, as shown
when the instrument is removed from the kiln, the humidity can be
easily determined from a simple form of chart which is furnished free
by the makers with each instrument.

The Recording Thermometer

[Illustration: Fig. 96. The Registering Hygrometer.]

[Illustration: Fig. 97. The Recording Thermometer.]

In Figure 97 is shown the Recording Thermometer for observing and
recording the temperatures within a dry kiln, and thus obtaining a
check upon its operation. This instrument is constructed to record
automatically, upon a circular chart, the temperature