Improvements in Apparatus employed in Wireless Telegraphy.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in Apparatus employed in Wireless Telegraphy.
We, GUGLIELMO MARCONI, late of 67, Talbot Road, Westbourne Park, in the
County of Middlesex, but now of 28, Mark Lane, in the City of London, Gentle-
man, and THE WIRELESS TELEGRAPH AND SIGNAL Co. LD., of 28, Mark Lane,
in the City of London, do hereby declare the nature of this invention to be as
follows:
In the specification of a former patent granted to Guglielmo Marconi No. 12039
of 1896 is described an arrangement in which the transmitter consisted of a
sparking appliance having one terminal connected to an insulated conductor in
the air and the other terminal to earth, whilst the receiver contained a sensitive
tube or sensitive imperfect contact, having one end connected to a similar con-
ductor and the other end to earth.
When both instruments are employed at the same station it is found that the
sensitive tube or sensitive imperfect contact is liable to injury by its close
proximity to the sparking appliance.
In order to obviate this objection we enclose the receiver, containing the
sensitive tube or sensitive imperfect contact, in a box of thick metal having only
a small opening into it, and we employ the same conductor and earth plate
for both instruments providing switches whereby these may be connected to
either instrument at will, and we so arrange the apparatus that the switch lever in
the act of connecting the transmitter and disconnecting the receiver places a
screen in front of the aperture.
COMPLETE SPECIFICATION (AMENDED).
Improvements in Apparatus employed in Wireless Telegraphy.
We, GUGLIELMO MARCONI, late of 67, Talbot Road, Westbourne Park, in the
County of Middlesex, and now of 28, Mark Lane, in the City of London, Gentle-
and THE WIRELESS TELEGRAPH AND SIGNAL Co., LD., of 28, Mark Lane,
in the City of London, do hereby declare the nature of this invention and in
man,

page_text: what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement:-
In the specification of a former patent granted to Guglielmo Marconi No. 12039
of 1896 is described an arrangement in which the transmitter consisted of a
sparking appliance having one terminal connected to an insulated conductor in
the air and the other terminal to earth, whilst the receiver contained a sensitive
tube or sensitive imperfect contact, having one end connected to a similar con-
ductor and the other end to earth.
When both instruments are employed at the same station it is found that the
sensitive tube or sensitive imperfect contact is liable to injury by its close
proximity to the sparking appliance.
In order to obviate this objection we enclose the receiver, containing the
sensitive tube or sensitive imperfect contact, in a box of thick metal having only
a small opening into it, and we employ the same conductor and earth plate
for both instruments providing switches whereby these may be connected to
either instrument at will, and we so arrange the apparatus that the switch lever in
the act of connecting the transmitter and disconnecting the receiver places a
screen in front of the aperture.
Figure 1 is a plan (partly in section) of an apparatus arranged according to
this invention and Figure 2 is a section on the line 2-2 Figure 1.
c is the
a is a metal box preferably made of sheet iron about one sixteenth of an inch
thick and a a¹ are apertures in it. In Figure 1 part of the top of the box is
broken away to show part of the receiving instrument b contained in it.
sensitive tube of the receiver having its ends connected to insulated contacts d d¹.
ee are the balls of the sparking appliance or transmitter which are connected
to contacts ff on insulating standards f2 f³. g is a switch lever of non-conduct-
ing material pivotted on the metallic top g¹ of an insulating standard g² and
provided with a handle h by which it is turned. jj are contacts carried by
the lever and connected to metallic plates h¹ which are in contact with the
top g¹, the latter being connected to earth by the wire l. m m¹ are similar
contacts carried by the lever g, and connected by the metallic plates n, and
flexible wire o, to the insulated conductor or surface p, carried by the post p¹.
When the instrument is to be used for transmitting as shown, the contacts j
and m¹ engage with the contacts f f¹, so that one of the balls e is connected to
earth, and the other to the conductor or surface 7. Similarly when the instru-
ment is to be used for receiving, the lever g is turned about its pivot, and the
contacts and m¹ enter the box through the apertures a¹ a¹, and are made to
engage with the contacts d and , so that the ends of the tube c are connected
one to earth and the other to the conductor or surface p.
If the apertures a¹ a¹ are kept at a certain distance, say 15 inches from and
out of the line with the sparking appliance, it will not be necessary to close them
whilst transmitting, but this may readily be done when necessary by the arrange-
ment shown in Figure 3 where 9 9 are shutters pivotted to the box at g¹ q¹ and
operated by a cord led over pulleys and connected to the lever g.
If a telegraphic instrument outside the box be employed the connections to it
from the receiver should be made by a third pair of contacts on the lever as no
wires should be allowed to protrude from the box.
The above described arrangement can be simplified by connecting one terminal
of the receiver permanently to the box. The corresponding aperture of the box
can then be permanently closed, and the contact or m¹ of the switch instead
of passing through the aperture is caused to clamp on to a piece of metal fixed
on the outside of the box. Or the box may be permanently connected to earth
or to the insulated surface or conductor. In this case one pair of contacts on
the lever can be dispensed with, if one of the balls of the oscillator is also per-
manently connected to earth or the insulated surface or conductor.
It will be obvious that the invention is applicable in all cases where both the

page_text: receiver and transmitter have to be connected to a surface or surfaces (whether
insulated or not) or to the earth.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we are aware that it
has previously been proposed, in a system of wireless telegraphy, (1) to protect
the receiver from the effect of the local transmitter by enclosing it in a metallic
box, (2) to use the same conducting surface or surfaces for both instruments,
(3) to connect and disconnect the two instruments by means of a change-over
switch, and (4) to open and close apertures in the metallic box containing the
receiver by means operated by the switch lever, and we wish it to be understood
that we make no general claim to such arrangement or combination of apparatus
but we declare that what we claim is:-
1. In apparatus comprising a transmitter, a receiver, a metallic box containing
the receiver, a conducting surface, and a switch, providing an automatic shutter
which closes the box when the transmitter is being used.
2. Apparatus substantially as described and illustrated in the drawings.
G. MARCONI.