Omaha daily bee. (Omaha [Neb.]) 187?-1922, 1917-04-02

Craig, Neb., March ZZ.-Io the
Editor OF The Bee: / would like very
much to see the answers of the follow
ing questions appear in The Bee:
/. Explain the work of the detector
in wireless Telegraphy."
2. Where can ! get some informa-
ton in booklet form ON wireless
Telegraphy" -
3.What was the "Decclaration of
London1" Why was it abandoned?
Or was it? ..-
4. How is the aerial wire on vessel
grounded?
5. Do the aerial wires have to be
No. IA copper wires? G. L.
Answers by DR.. Frederick H.
Milliner:
First-Explain the work of the
detector in wireless telegraphy:
The question asked is not clear and
is very broad. No direct detection
of the electromagnetic waves
emanating from a radio-transmitter,
that is, the sending apparatus, is pos
siblc.
We are limited to causing waves to
induce oscillations in the conductors
of the receiver and to detect these
oscillations by means of suitable ap-
paratus. In other words they cannot
be heard or perceived by the human
organs and so we have to have an ap-
paratus to do this. This apparatus is
called a detector. There are six or
seven different varieties OF detectors.
]. Thermal detectors.
2. Magnetic detectors.
8. Imperfect contacts or coherers
detectors.
4. Electrolytic and other detectors.
S. Crystal detectors.
6. Incandescent lamp and gas de-
tcctors.
The detectors in most general use
are the gas or incandescent lamp de-
tectors and are known as audions,
audiontrons and ultra-audions.
| presume that the action OF the
detectors which you ask, is that Of the
crystal detectors which are galena,
iron pyrites, pro-lusite, Carbo-
rundum, titaniur,-dioxide. These de-
tectors are single crystal detectors.
In addition to these we have second
class which is combination of more
than one mineral. The one best
known with which the greatest sue
cess has been made, is the Perikon
doctor by Pickard, which is a COM
bination of zink-oxide and copper
pyrites. The action of The perikon
detector is thermoelectric, and it has
been proved that this detector is SEN
sitive only if the contact is limited
to a point. Second, it operates with
out a battery. Third. the direction
Of the current under the influence OF
the received oscillations is,always in
the same direction. Gadena, carbo-
rundum, titanium-dioxide, iron pyrites
pyro-lusite, etc, are &C lass of de-
tectors the action OF which is that OF
rectifer, that is, broadly speaking,
altering or changing alternating cur
rent so that it doe, not reverse itself
but flows in one direction. In other
words, changes alternating current
| into form of direct current which is
| received in telephone receiver.
Second-Where can get some. IN
| formation in booklet form on wireless
telegraphy?
Amateur Books-V. H. Laughter,
A. P. Morgan, ]. Z. Murray and
"Wireless Telegraph for Amateurs
and Students" by 7. NJ. St, John;
"Wireless Telegraphy," by Morgan.
Technical Wireless Books-"Wire-
| less Telegraphy." by Zenneck;
"Theory and Practice Of Wireless
Telegraph" by Flemming; Manual
Of Wireless Telegraph" by Flem-
ming; principles Of Wireless Iele-
graphy," by Pierce; Wireless Tele-
graphy and Telephony" by MAJ
zatto; Wireless Telephone" by
Ernst Runner; Electric Waves" by
Hertz.
Third--What was the Declaration
OF Londonf
Because of its direct bearing upon
naval and military operations and
upon the maritime intercourse be-
tween different countries, it soon be-
came evident that radio-telegrapf