The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1900-05-08

ments and Celebrations on the optical
! principle Of the zoetrope. There are but
few essential things which successful
machine of this sort must accomplish.
| but their accomplishment Is not in
every case altogether easy. The pic
lures must be presented 50 rapidly that
there Is no appreciable break between,
either in light or in positions. Of the
| moving figures. The light must be adj
! mitted exactly as the picture is in place
and must be cut OF just before the pic
ture is charged. The different pictures
! must be shown in exact register or
there viii be a shifting or dancing eff
feet, which is not intended, and is un-
pleasant
Instead of a number of separate
cameras to take the pictures. a single
instrument IS used so arranged that
the shutter IS in practically contin-
uous vibration at the rate Of thirty or
more exposures a second In its proper
place behind the shutter and lens
continuous strip of Sim Is run in time
with the shutter. It's motion is neces-
sarily jerky. for it must be at rest for
The exposure. while the shutter * open,
ard move ahead one space while the
shutter is closed. BY the development
Of this long strip Of film there is OBJ
tanned series Of negatives. from which
pCttives are printed. in similar long
ctTirs. and these positive strips are
used in the viewing or projecting in
jtrument. II the pOsitlVeS are exam
ined separately il viii usually be diff
cult if not impossible to detect any diff
ference in positions of the figures IN
pictures which lie near together in the
strip, ana when thess pictures are
passsd through the projecting instru-
ment at the same rate as that of the
taking camera the movements Of the
figures UPON the screen appear natural
and lifelike.
The projecting instrument for moving
pictures is a regular projecting lantern,
with the addition Of mechanism, at
taC1ed to the objective. for keeping the
shutter and the pictures III motion This
motion is kept up by a motor or by
hand wheel, and the shutter or fan is
run by the same mechanism that moves
the film. A picture is held against the
opening while the lens is uncovered,
then released as the vane covers the
lens, and tie next one takes its place,
to be shown, in turn, the instant the
vane has passed.
Practical Uses.
The chief use to which moving pic
lures have been applied thus far is that
Of entertainment, and unfortunately
the subjects which have aroused the
mos, interest have been prize fights.
There are. however, many directions in
which this instrument may prove of
value. 1t is proposed to make use of it
in war and how far such an idea can
be carried out we shall perhaps know
better after the close Of the present war
in Africa There are certain practical
difficulties in having a kinetoscOpe
camera at the front always ready for
service, even If it's uee were permitted.
The value of a series of inatantane-
Gus photographs taken at short inter
walls in Analysing rapid motion is suf-
fciently obvious By passing the pic
lures through the viewing Instrument
at a reduced speed, the motion may be
made as slow as we wish and its ma
ture clearly seen. Another application
of this principle which mas recently
been proposed is less obvious. 1t * pro-
posed 70 take photographs at long in
tervals Of movements which are very
slow. Then, passing the series of pic
lures from these negatives through the
viewing instrument at Ule usual speed,
the slow motion becomes rapid Sup
pose, for example, that a photograph
is taken every few hours Of a sproutins
seed and growing plant. When shown
by the viewing or projecting InStTu-
ment the sprCUt may be seen breaking
through the ground gaining in height
and size, putting forth leaves, buds
and branches and reaching its maturi-
", all in a few minutes. The same
method may be applied to many things
other than plants. To this modification
Of the principle of moving pictures 1t
has been considered necessary to give
new name, the 'phaLCoscope.