We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
arc stream. The hole in this screen is approximately 1 to 2 millimeters larger in diameter than the crater. This allows clearance enough to take care of any slight change in position of the positive carbon while rotating and gives a clear field approximately 1.5 inches in diameter on the comparison plate. The light from the small part of the tail flame which is included by this clearance is negligible. This was demonstrated by tests with larger and smaller openings in screen A. Screen B shields the operator of the illuminometer from the crater light. The hollow tube projecting from the side of the box furnishes the necessary opening for the illuminometer. The correct position of the crater with respect to Screen A and the comparison plate is checked by means of the substitution of a false back with an opening slightly larger than the field of view of the comparison plate, and a telescope F placed at the back of the opening, as shown in the figure. The angular distribution in a horizontal plane was obtained by rotating the lamp about the crater as the axis. The size of the crater opening was obtained by measuring the craters of carbons which had been burned at the various currents. The intrinsic brilliancy was calculated from the above data by the usual method.
The spectral energy distribution curves were made with practically the same set-up for excluding light other than that from the crater. They were made with a quartz spectroradiometer used in connection with a thermopile with calibrated transmission screens, according to the procedure described by Coblentz6 and Greider and Downes9.
with the higher current concentration, gives the greater candle power.
The crater light is only approximately 68 per cent of the total light
Ns
TIONfiL \i
SC-H
iNTfLNSn
Y C
m
CANDU
FOWER
of CRATCg
V* 1
_t6:-rr
6 MM..
/
136
MM >
CORPS NT
Figure Two
from the high intensity arc as measured directly in front of the crater. The additional light comes almost entirely from the tail flame which streams out of the positive crater.
The candle power as well as the steadiness of operation is affected by the angle and relative position of the negative carbon with respect to the positive crater and by the voltage maintained across the arc. The angle is usually fixed by the construction of the lamp. The best results were obtained when the relative positions of the negative carbon and positive crater were such that the negative flame just brushed the lower edge of the positive crater as shown in Fig. 3 -A. If the negative flame bathed the
Discussion of Results
The candle power of the crater light directly in front of the arc is shown in Fig. 2. As would be expected the candle power increases with the current. When the same current is used on two different size carbons of the same composition, the smaller size carbon, that is, the one Ten
lower outside of the positive crater appreciably, as shown in Fig. 3 -B, the candle power decreased probably because some of the current was taken on the outside of the positive crater thus lowering the current and energy concentration on the inside of the crater. If the edge of the negative flame were considerably ahead of