The San Francisco call. [volume] (San Francisco [Calif.]) 1895-1913, 1895-08-25

| INEITnlN05
W. .[sls[I,a
VIZ WONDERFUL TIME
MEASURING INsTRU-
MENT.-Much interest has been aroused in
the scientific circles of Europe by what is
claimed to be the most wonderful timing
instrument in the world, the pendulum
| chronoscope invented in this country by
Professor G. B. Bliss, and perfected in the
| psychological laboratory of Yale by J. j.
| Hogan. 1t can be used with the quickness
| of q stop watch, without the help of either
electrician or mathematician. 1t measures
| accurately down to the one-thousandth
part of a second and is already taking the
| place of the old-style chromosomes in sci
| entitic laboratories. The instrument is
an ingenious combination of mechanical
and electrical attachments. 1t tells the
speed of a cannon ball, the lapse of time
| between the firing of pistol and the start
| ing OF a runner, and it is proposed to in
troduce it into boxing schools, so that
| pupils can constantly test the speed with
which they can deliver blow, and so note
] the lessening of the reaction time between
the brain impulse and the blow on which
| increase of skill depends. The machine
consists of a pendulum and pointer swing
| ing independently on the same axle. The
| tip of the pointer travels along the face
of a curved scale or indicator, which is
| graduated to show the one-thousandth
required for the transmission of
any given impression button
is pressed. This sets the pendulum in
motion and the result is registered on the
scale. If sight test is to be made, when
the pendulum comes in contact with the
pointer a black shutter is raised from
light disk. AS the disk flashes on the
sight of the subject he touches button
and the pointer is instantly stopped. The
average time between the exposure of the
disk to the sight and the pressure of the
button has been found to be 0.300 of Sec
ond. The reflex action for sound is
| quicker than this, being put at 0.130 of a
second. The discerning of colors is looked
upon as an important test in the determi-
nation of certain traits of the pupil. A
square of some color unknown to the SUBJ
| ject is to be exhibited from behind a shut
| ter. He is told, for instance, to press
the button when he sees blue. This test
sometimes extends to one-quarter of a sec
ond. The trials with odors, noises and
|
| of these tests in school work is to enable
| teachers to ascertain the mental charac-
| teristics of their scholars. Under the old
/ system of teaching all the scholars in
class were grouped together and subjected
to the same infexible rule of tuition, re-
gardless of their differences of tempera-
| ment and intellectual ability. The chrono-
scope puts an end to such crude methods
and reduces teaching to a science.
l
! ELECTRIC LIGHTS IN PLACE OF SUNLIGHT
IN PLANT CULTIvATIoN.-Mos praiseworthy
work has been done by Professor Bailey
| in testing the effect of electricity and cleo
| trio lights upon plant growth, and his re-
suits seem to suggest new order of plant
| culture. He found that the burning of an
uncovered arc light of 1000 candlepower
caused plants to mature earlier than others
in greenhouse lighted only by the sun,
and the nearer the plants were to the
| light the faster was their growth. This
rapidity of growth was in some instances
| SO great that the plants could not supply
themselves fast enough with food, such,
for instance, as water. The plants had to
| be removed to a distance before water
| could be supplied quickly enough to as
suage their abnormal thirst. Under the
influence of the strong, continued light
! plants would assume all sorts of novel and
! Singular DdDllS. COule WOulQ run 10 SEED
before the leaves were formed; others
would be gaunt and struggling, while
others, again, would have their stems
| twisted into fantastic shapes. The colors
of tulips became deeper and richer in
shade. but the colors lost their intensity
after four or five days. Petunias grew
much taller and more slender, and
| fasely. Some plants would be found
| in the morning stretching out toward the
| electric light as if yearning for it at an
| angle of 45 degrees. During the day they
would straighten up, but they would bend
| forward toward the light again at night.
Lettuce benefited so much by the artificial
| light that three weeks after planting it
was twice the size OF that planted at the
same time which had received only SUM-
| light. A greenhouse was so arranged that
one-half the building might receive the
| light at night. The plants in the lighted
apartment were far superior to those in the
darkened one. A bed of 100 vioiets was set
in the lighted compartment, half the bed
being covered each night with a black
enameled-cloth box provided with ven
tilation. In three weeks the plants under
the electric light began to bloom, while
those whose only light came from the sun
did not bear bud for five weeks. The
effect of the light is upon some plants
almost magical Panes of glass have been
pldcSu III lTOuL Ol tLclu, 81 DIS W cover only
half their leaves. After slight growth
the parts of the leaves receiving the I'M
covered light will show clear boundary
line outside of which the leaves are much
healthier. Professor Bailey believes that
if grown under electric light for several
generations plants will adapt themselves
to fastened growth, just as they have be-
come used to greenhouse life in winter.
THE VALUE OF TELEPHONE SERvICE.-The
cheapness of the telephone service has
been illustrated convlncingly by the gen.
eral manager of Missouri exchange.
During the. day he made the operators
keep a record of the complaining SUBJ
scriber, and at night he knew exactly how
many times the telephone had been used.
He finds out that it is cheaper to use the
telephone than postal cards for any kind
OF business. The way he figures out this is
TO divide the cost of the telephone for
year by the number of days, which gives
the cost to the subscriber per day. A tele-
ephone that costs $72 year costs about 20
cents day. If the telephone has been
used twenty times in the day. each call
has cost the subscriber just l cent, or
the price of postal card The average
telephone, however, makes between twelve
ioy, nd 4 oo1j