the life of Philo T Farnsworth - Early Television Foundation

98 THE STORY OF TELEVISION
for a fraction of a second after it disappears, does not perceive
this interval of darkness.
When the shutter was down and the screen darkened, the
scanning went on over the darkened surface, a line at a time in
the same manner as over the image. This brought intermittent
black flashes on the television receiver tube which gave to the
eye the appearance of a violent flicker. The fact that the pictures
were scanned at the rate of 30 per second while the projector
ran them at the rate of 24 per second added confusion and
made the flicker more unbearable. Consequently, to televise
them successfully means had to be devised to scan the picture
with the film running continuously. Since the picture was transmitted
one scanning line at a time, the shutter could be eliminated.
With this done, the film flowed evenly across the scanning
area and the picture elements were transmitted for reproduction
to the received without interruption. This eliminated
the major
difficulties of the flicker. The operation required nice
timing and precision. Here again Farnsworth's great ability in
thinking and actually visualizing an operation in mathematical
terms made it possible for him to develop a new system to satisfy
his requirements.
The purchase of an old motion-picture projector for use in
the experimental setup was one of the first times when it became
imperative for Phil to overstep the limit of $1,000 set as
his monthly allowance. The staff of the laboratory also had to
be increased to meet the expanding program of research. In this,
as
in subsequent enlarged expenditures, the financing group
were lenient and co-operative.
While work was going on in the reconstruction of the motion-picture
projector, changing and testing was carried on day
in and day out throughout the whole embryo system. The
black figures painted on glass, the photograph negatives, and