New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1897-07-04

In the primary circuit which also contains an
ordinary Morse key. X The turns OF fine WIRE
composing the secondary coil, are so much more
numerous than those Of the primary that the cur
rent induced In the former has very high volt
age or penetrating power. 1t would leap an air gap
OF at least six Inches So long the key Is open
nothing happens; but when It Is closed. and tho
primary circuit is complete the secondary begins
sparkling with amazing rapidity. and set Of
electromagnetic waves. about two hundred ana
fifty million per second. are thrown out sideways
from an imaginary line connecting the centres OF
the big spheres let say at d. The zigzag line
which Mr.. Preece has drawn on the under side OF
the cylinder IS not intended TO represent wire
but the series Of invisible electromagnetic waves.
THE MARCONI RECEIVER.
The most original part Of Mr.. Marconrs appa-
ratus Is his receiver or relay. While II WORKS on
the same principe Hertzs resonator 1t intro
duces a new feature. 1t is something moro than
nero ring carefully tuned" to respond to vibra-
lions OF q certain frequency. In q sealed glass
tube an inch and half long and perhaps quar-
ter OF an inch in diameter. he inserts two cyin-
drlcal bits Of silver. separated at their bases by
half a millimeter, about one-fifteth OF an men,
The outer ends OF the silver "poe-pieccs" are con-
nected with wires that pierce the glass The tube
is made alright. ana high vacuum is created
within H. But before these last two steps are
taken the space between the butt ends OF the silver
pieces Is filled with mixture Of fine nickel and
silver filings to which trace OF mercury mas peen
added Now, If local battery, b. such as IS
used IN every country telegraph Office be connected
with the apparatus and an attempt be made to
serd current through the latter. there Will be no
success unless tho tube should be exposed; side
ways, to the electromagnetic waves sent on oy NE
filings act like an insulGtor The tiny psrtifes lie
savs Bn when they come
the Hertzian waves. they are polarized or ar a
ch hafeq and Conduct the current Consequently
ordinary teegraphc, "sounder" s Is placed IN me
nickel and silver filings are polarized by the electro
magnetic waves. In other words, 1t Will repeat
key connected with the translnitter.
Two thin metallic wings. WV. attached to the
b rcecy Is u D 9 to R
mitter If a crowbar is dropped on q pavement I
will ring out certain note. Vary the amount OF
metal In It, and you change the note
ELECTRICAL RESONANCE"
Similarly, every electric circuit which has what
Is called capacity" has a natural rate Of vibration
Of its own. This can be varied in certain ways
Such a circuit can be made to vibrate most easily
under the influence Of the current in another con-
ductor by tuning II to correspond with that con-
ductor Hertz revealed this fact to US several years
ago The phenomenon Is known as electrical
resonance"
After the particles in Marconrs receiver have
once been polarzed. they show tendency to
cohere rather too closely. Such result Is unde-
s!rable for It would encourage flew OF the local
current when no waves were coming in from out
side Consequently. the young Italian has attached
TO his apparatus a tiny. vibrating hammer. II.
worked by "A second local battery. This delivers
ra bid succession o. ligh; blows on the tube. near
the filings. and "de-coheres' them. as Professor
Lodge would say.
When an Induction coil powerful enough to gvo
six-inch spark IS used with the transmitter. Mar
conis receiver will pick up the waves at dis
eo of 5H1T Of s IT,
CURED; The length Of spark Is convenient
a current, Thus far, the new wireless system has
been used only to cover intervals OF eight miles.
A coil capable Of sending further than this would
be very costly far more so than eight or ten miles
OF wire Hence Marconis method Is not likely 10
dspacc Morse's for general service. 1t seems TO
be best suited TO secret communication IN time OF
war TO fog signalling, to telegraphing TO light
ships or Islands lying several miles off shore.
Other exceptional situations where 1t would be
ayaila bic may be found but II Is easy to that
it's sphere OF usefulness Is very limited at present