The San Francisco call., 1895-05-19

THE ELECTRIC WEED KILLER.-The elec-
trio weed-killer, which was experimental
| upon some time ago with varying results,
is said to- have been brought down to
practical shape. The device was intended
originally for the destruction of grass and
weeds along railroads. 1t is expected to
be especially valuable in the destruction of
plants of the thistle tribe, in which the
root itself must be destroyed in order to
annihilate the weed. 1t is claimed that
the use of the electric weed killer will re-
duce the cost OF keeping railway lines clear
of vegetation from $40 to $50 per mile per
year. The operation of the device is based
on the varying conductivity of vegetables !;
the more moisture they contain the less
resistance they offer to the current. The
apparatus consists of an alternating gen.
orator mounted on car producing elec-
| tricity at 2000 volts pressure and stepped
up'' to from 5000 to 24,000 volts, according
to the kind and quality of the vegetation
! to be destroyed. The current, after being
raised to the required voltage, is conducted
| through series of fine wires or brushes"
| to the tops of the weeds or grass; the other
! side of the current being made through
| the wheels of the car to the ground. The
current leaps from the suspended brush to
| the weeds and passes through them to
The current transverses the entire length
| of the plant, from the topmost leaf to the
roots, rupturing it's cellular tissue and
| completely destroying it. The root is
generally affected more than the rest of
| the plant from the fact that it contains
| more moisture.
| EXPLOSIONS IN CoNDUITs ARISING FROM
ELEcTRoLYsIs.-The recent scare with re-
| gard to explosions in electric conduits has
! set inventors at work to find remedy, and
| to that end quite number of suggestions
| have been made. 1t will be remembered
that the committee which reported on the
! fatal st. Pancras explosions in London
| found that an alkaline incrustatlon on the
lnsulators OF the electric mains had caused
sparks, which ignited the explosive mix
! ture OF gas and air in the conduits These
| sparks were due TO the lncrustatlon acting
as an imperfect conductor. Nevertheless
the existence of metallic sodium or potas-
SUM IN the deposit, taking fire in con-
tact with moisture, might also ignite the
explosive gas. 1t was decided that the de-
poslt was due chiefly to the electric de-
| composition of alkaline salts in the soil,
| which were conveyed by moisture to the
wooden supports of the conductors. The
committee recommended the use of diff
1erent msulator, the disuse OF wooden
bearers, and regular and proper inspec-
ton OF the conduits throughout their
whole length.
TELEPHONE OUTFIT FOR FIRE BRIeADEs. =
Many city fire departments are now adding
telephones to their brigade outfit, with
the effect of vastly increasing the efficiency
OF the department. When the engine ar
rlyes at the fire one of the firemen con-
meets the telephone outfit, which weighs
only pound. with the fire-alarm line.
Ihls gives means of communicating IN
stantly with headquarters. 1t is no slight
advantage to be able to transmit verbal
report OF the progress of the fire, and order
up additional engines where the occasion
does not justify calling out an entire relay
OF apparatus, and thus uncoverlng add1-
tlonal territory. In point OF fact, the use
or the telephone transfers the active man.
agement of the whole fire department to
the scene of the fire at which the depart
ment is at work.
ELECTRICAL INDUsTRIEs.-The amount of
capital engaged in the electrical industry,
not including telegraphy, is estimated as
follows: England $10O, 100000, France $780,
600, 600. Germany $500, 900 900, Austria,
Italy, Spain and Switzerland $3.50 900,
Kussla, Sweden. Norway and Denmark
S50,OO0,OO0, the United States $45O, 600, 900,
Canada and other American countries
a5O,oOo,000, making total OF about $3.50,
100000 in Europe and $500. .00o,0 600 in Amer
lea.