New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1891-09-07


wherewh to handle the data when ne gets 10 and has
designed instrument, which has been made for him
by the United States Coast and Geodetic survey 10
facilitate his test.
THE PHENOMENA OF TERRESTRIAL MAGNETISM.
But 1t is Professor Bigelow's recent discovery
regarding terrestrial magnetism which is OF the
greatest immediate practical Importance, TO say
nothing of Its far-reachlng results. IL comes
Just at the moment when the scientific world was on
the verge OF abandoning elaborate concerted move
ment for solving great mystery.
True as tho needle 20 the POLE" like many other
SMILES. is an imperfect comparison. That Little strip
of steel by which every navigator in the civnhzed
globe steers his craft and by which every acre OF Iao In
the world Ii surveyed before Its bounds are
record does not, except in rare Instances Pott uuo
tain centre called magnetic pole, some distance rom
the geographical pole; and but for carefully drawn
less variation In every part of the globe, our SHIPS
would be wrecked and our boundaries would be wrong
After remaining steady all night, the needle will at
slowly eastward until or or 10 O'Clock, ana then
move westward past the starting point unui noon
sunset. This oscillation is very small,
minutes Of an arc at Washington and Philadelphia,
rather more Toronto, stu greater in Labrador ana up
mn much as two full DEGREES on so%s days osca
more sudden, Violent and irregular perGrbstons called
magnetic storms" is greater in summer than in winter,
greater at the equnoxes than at the sotce and from
so 10 10 per cent greater at the maximum than at the
minimum stage OF sunspOJ frequency In the eleven
In the reverse direction and there are few stations
where there Is double, instead of only SINGLE com
plee daily huctuaton To the discovery these facts
he world owes much to Sir Edward Sabine, who
secured the establishment of magnetic obserVatOles
SnSeT british na R'e Credit If due 1S tn IN e
OF the United States Coast survey and to the scientists
of other lands. In order further to investigate TINS
u1atfp larVe Vyi "A OF
lying law that would explain the phenomena already
eH m % u6 ID e napoeS
ernments, at thirteen 'crcumpoar stations, eleven IN
the northern hemisphere and two in the southern The
and until few days ago 1T was expected
that when the international Polar Conference
% goSe It o Ms%Gh S' and Ss its eaoT But
with him the announcement OF Professor Bgeows dis
covery, and will urge continued observation with spe-
vOlved, and extending their application Professor
Bige!Ow's explanation is accepted as correct by so
last wear presided over the section of physics In the
American Association for the Advancement of Science;
magnetic work of the United States Coast and Geodec
Survey; by Professor Mark W. Harrington, the new
chief of the Government Weather Bureau at Washing
ton himself an expert astronomer and mathematician,
and by General Greedy. II received with much
mers at The recent meeting OF the American Assoca-
ton the Advancement Of scenGe and without doubt
II will profoundly impress the European saVants 10
whose notice IL is about to be brought.
MAGNETISM RADIATEs WITH THE SUNLIGHT.
Terrestrial magnetism results, Professor Bigelow
believes from solar energy transmitted to the earth
along two sets Of lines the coronal. curved and
crossing the plane of the eclpto near us perpen-
diculary the other straight, like the rays of Hight
and heat. and parallel with the eclptc. The latter
be holds 10 be me most important at least as re-
CARDS the daily oscillation of the needle What takes
place every day, them the earth rotates in these
rays practically what takes place in dynamo for
producing electricity 1t is only necessary TO move
any conducting substance past magnet, across It's
lines OF force 10 have THAI conductor made magnet
itself for the time being by induction and for sys
TEN OF electrical currents circulating around its axis TO
he excited. While the conductor approaches Its nearest
end acquires, let say, north-pOle magnetism, and
the surrounding currents 60 in one drecuon counter
clockwse but when the moving conductor has passed
tie stationary magnet, this same nearest end, now
pcedng, reNerSeS It's polarity, ana IS Ike south
pole. In dynamo there scores, not to say hun
dreds Of such conductors arranged on circular 10
tatng fraIne which are thus brought In succession to-
ward and away from the dominating magnets. Pro
fessOr Bgel0w conceives OF each spot the eartbs
surface as being rotated daily past the sum- aud going
through this same eSlcf.ence. From dawn TO noon
it approaches from noon 10 sunset it recedes the
various Instruments In an observatory registering the
various compOnents Of the magnetic situation Induced
Immediately underneath them first swing in one d.
iecon ana then In the otner and when they are car
red out Of sight OF the sun at night, come 10 state
of rest provided, Of course that exterior disturb
ance arises. Were the earth stationary this radiant
influence would be felt insantaneousy but owing 10
It's rotation there is lag Of about twenty degees
Along these radating lines light and heat pass out
ward from the sum- the magnetic force is shown to be
directed inward.
To prove, rather to build up this law Professor
Bigelow adopted the following method Thirteen
stations well distributed about the globe especially
in the northern hemisphere, carefully selected
Their magnetic records for June, 1853. examined
This was one OF the months of the international polar
observation, and the sun now shone constantly in
the Arctic regions. For each Of the twenty-four
hours, at each station, the mean of magnetic dis
turbance. in extent and direction computed.
And then, with due regard for longitude. disribu-
ton of figures was made which would show the exact
magnetic situation at all points at certain given IL
slant. OF course, the instruments at each station
were at a different stage of their diurnal swing from
twenty -four different hourly positions. This involved
exceedingly intricate computations, which only adj
vanced mathematician can follow. But the result
beautifully organized system of lines OF force.
corresponding to those which Maxwell and Thomson
have already prescribed and illustrated, be found
when polaTzed sphere is inserted in " field Of
force"
Work in the immediate future, Professor Blgelow
thinks, should be pushed b. these directions: From
the agreement between IN Dry and observations Ger
tain constants" should be ascertained. The strength
earth, and the atmospheric resistance 10 magnetism.
He would have the relations between magnetism and
weather examined afresh from this vantage ground
improved magnetic charts supplied to navigatUT and
Observatories established. not very much at
random, but in picked localities to render the record
more perfect. He also believes that inequalities in
the motion Of the perheiOn of Mercury and the moons
node-the inadequatey explained the theory OF
intra Mercurial planet and the other not accounted
for by gravitation-can be cleared up by proper
of his recent discovery.