The Penn's Grove record., 1888-11-24

PrOf. VIM. rhomson's Views on the
Subject OF Electrical Discharges.

|
Prof. VIM. rhomson's Views on the
Subject OF Electrical Discharges.
At q recent meeting Of tho British
Association Sir William Thomson. fol-
lowing Mr.. Preece, discussed 1t length
the subject Of lightning and the means
OF preventing destruction by its dis
charges. Mr.. Thomson said he thought
that II Professor Lodge continued his
work he would End q explanation Of the
very great discovery he had made In
respect to iron afIording q better dis
charge to electricity than copper. He
labors, keeping the conditions as nearly
alike as possible, and would compare,
for instance, q thin iron wire with q
thin lead or brass wire Of the same
conductivIty. There was yet q good
deal moro to do il q proper account
were taken Of inertia, and the other
point the professor lad accumulated,
that energy must be got rid Of In some
way. either In q conductor or else
where; IL In the conductor then there
must not be energy enough to melt the
conductor. An Interesting fact bad
been mentioned that In o row of horses
struck BY lightning only the first and
last were killed, although the discharge
passed through all, and it was . com.
mon experiment to give . shock to q
hundred or more persons whose hands
were Joined in q circuit, and there was
line experienced the shock more fully
than those in the middle. There were
two potent Influences at work In such
cases, the want Of perfect insulation
and self-induction. The influence Of
self-induction might be tried and the
same thing might be tried in as nearly
Is possible similar Insulation, the same
number of people arranged In q circle.
In that . self-induction would BIZ
more influential in causing the dis
charge to pass through the door be.
reath rather than keep to the compare.
lively good conductor of the ring Of
persons; or people might be ranged In
Q zig-zag row, and then self-inducti0n
| will not have tho same tendency to
| cause the discharge to leave the line OF
the best conductors as IL the bodies
were placed in q large circle. The Inn
perfect insulation OF standing on the
Moor would be much moro potent when
the persons were arranged In . wide
| circle.
MI. Presce had spoken Of the impos-
siblllty Of forming a conception Of the
enormous augmentation Of potential In
the circumstances referred to. But If
the term '.inertia" were usec-and the
speaker fully agreed with the judici-
ousness Of that term-comparison
might be made with the steam ham,
mer Or the hydraulic ram. The begin
, ing was with Q comparatively gentle
force, the weight bringing down the
hammer until 1t produced an exceed
ingly intense action In the blow; or
taking the hydraulic rama we'll
known analogue for high potential for
self-lnduction In an electric clrcuit-it
would then be zen that Professor
Lodges explanation was quite valid.
Referring to what had been said about
~oscillatory discharge In ordinary light
ming, and also as to duration Of the
charge and multiple flashes. Sir VII.
liam thought these aspects OF the case
must be distinguished from one an
other. There may be slow discharge
and MI. Abercromby had referred to q
ball OF lightning running down the street.
Arago had spoken Of q ball Of light.
ming that had entered at the window,
and bad run about among people rub
blng up against their legs like q cat.
The speaker did not attach much
| credit 10 this statement, which was re-
ported by . tailor. Sir William con.
sidered that these supposed exhibitions
OF ball lightning were mostly to be ex-
planned alphabetically. People have
been looking In some direction when
the Dash comes and an intense action
10 produced ON the centre OF the retina.
Naturally, after such q startling incl.
dent. all eyes are moved. and each per-
SON looks about to SEQ what has hap
pened. They look along the door, up
. wall, or toward . window. and then
q spot Of light, which is the persisting
impression on the retina, accompanies
the movement of the eye.
The speaker believed Mi. Preece wal
right in speaking Of the multiplicity Of
flashes Of lightning, and the expert.
mental evidence given by that gentle.
man was entirely borne out by what
Sir William had noticed. In 1910, al
Frankfort, be had noticed triple and
quadruple flashes repeatedly. These
occurred at such short intervals Of
time that there could be NO doubt but
that they were somehow connected,
and yet the interval was certainly long
enough to show that there were
several flashes. Since then he had
frequently seen similar phenomena.
Mr.. Abercromby had said it did
not seem to be q repetition OF flash
along the same course, but . succession
OF connected flashes, and to this the
speaker agreed. 1t wa . sort OF break
ing down along many lines and all over
the plaza. Light had been spoken Of
a. tending to induce flashes. 1t seemed
as II the very nne oscillations Of lighl
actually put the air into . condition
which ID more easily disruptive than all
which Is not agitated by light, but
that would not account for the time
interval, and Sir William thought
that something might be attribu.
ted to sound. The FIRST fash does pro-
duce . tremendous disturbance In the
air, probably causing . very per-
feet vacuum in the place Of tho fash;
and after this follows q knocking TO-
gether Of the air. 1t was difficult Ia
account for an electric fash in the all
otherwise than by supposing q crack III
the air suddenly filing up, and that
producing an exceedingly sharp elastic
disturbance. 1t was quite possible that
that elastic disturbance, propagated, at
q rate nearly equal to the ordinary
| velocity Of sound, to another place
where the air Ia In q state Of high ten
sion. and ready to break down. would be
caused to break down. Thus 1t might
be that one dash caused considerable
numbers OF others at short intervals.
It was a most interesting subject, and
might be easily investigated further
by the aid of photography. Many in
teresting experiments had been mad
on the magnetization Of steel needles
nv n halIY In which therA ara ~elActric