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.
3S2
RICHARDSON'S BLUEBOOK OF PROJECTION
( 131 ) If the length of the arc is increased beyond that shown in Fig. 94, the form of the arc will be sustained, if the operating conditions are proper, until the length is approximately 0.35 inch (8.9 mm). In Fig. 97, A shows the arc immediately before and B after such a point has been reached. At and beyond that length the arc has a tendency to move upward, so that the lower part no longer bows down appreciably and the upper part and the tail-flame become greatly extended. The highly luminous portion close to the electrode likewise becomes distorted as shown at B in Fig. 97 and the arc is unstable to
5
i
5? 400 a
a 1S0
t
2 3oo
| JSO
<
S 200
>
a ioo S so
-^^^ ^"^v
/ \
-3 + c
f \
DADIU5 OP CCATER IN INCHES
Fig. 95. — Intrinsic brilliancy across crater face ; 8-mm. a-c. high-intensity carbons, 80 amperes, 25^ volts.
such an extent that it will repeatedly jump back and forth between the positions shown at A and B in Fig. 93.
(132) Another condition that must be considered, and if encountered, corrected, is shown in Fig. 98. The arc being of medium length would ordinarily have the appearance shown in Fig. 94, but is disturbed by external sources, so that it appears very much as at B in Fig. 97. It has a tendency to snap back and forth between that position and the one shown in Fig. 94, causing variation of the current and voltage, accompanied by flicker and uneven light distribution. This condition may be caused by too strong a draft in the lamp house, by an unbalanced magnetic effect due to a poor arrangement of the current leads, or by any other factor that would tend to distort the arc.
(133) If we assume that the design of the lamp