A SEMAPHORE INDICATOR FOR ELECTRIC BELLS
Year: 1885

page_text: I, JOHN DAVID ADAMS, of Marlborough Works, Marshall Street, London, W.
Engineer do hereby declare the nature of my invention for A SEMAPHORE
INDICATOR FOR ELECTRIC BELLS, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement:—
In hotels and other large establishments it is essential, or at any rate desirable,
when a bell has been ruug, to have some means of ascertaining whether and when
the bell has been answered-With systems of Electric bells, an Indicator box is
generally provided, having a number of indicators, one for each room, which is
displaced by various methods, and shews which bell has been rung.
In private houses and small establishments, such indicator box is placed in the.
servants room, and as soon as the bell is answered the indicator is replaced
mechanically by the servants. But.in hotels and other large establishments, it is.
expedient to have an indicator. box on each floor, in the service room, so that when.
a bell is rung, the servant has only to go to the service room on that floor to see
which bell has to be answered. Under existing circumstances, the indicator would
have to be replaced in the service room, which perhaps is a long distance from the
visitors room, entailing a great loss of time and labour to the servant who has to
go back thither; and should another bell be rung in the mean time, there would be.
no means, other than going all the way to the service room, of ascertaining which.
bell had just been rung.
Now the object of my invention is to obviate this trouble and difficulty by
providing to each room a semaphore indicator, the use and construction of which I.
will proceed to explain.
The Semaphore is fitted outside each room in the corridor, and is provided with.
an arm made to drop down when an electro magnet is excited. It is painted red.
or some other bright colour, so that when it falls it is conspicuous from the other
end of the corridor, or any other desired distance. The arm is normally held in a
vertical position, and hid from view in its case, by a small catch on the armature of the
magnet; but when the visitor rings the bell and completes the circuit by the contact
button, a current passes through the magnet, depresses the armature, and releases
the semaphore arm which drops into a horizontal position through a slit in the case
and presents itself in a conspicuous manner. At the same time, the current passes
through an electro magnet in the indicator box in the service room, and causes a
pendulous tablet to swing before an opening in the indicator box and display the.
number of the room where the bell has been rung. This pendulum indicator is
actuated by an armature placed between two electro magnets and is of a well
known form. To this' I make no claim. When the servant has gone to the
visitor's room and answered the bell, she replaces the semaphore by pulling a cord
attached to the arm of a lever-The mechanical act of raising the seinaphore arm
makes contact, as will hereafter be explained in referring to the detailed con-
struction of the semaphore, with a second set of wires, the current in which passes

page_text: through the other magnet of the indicator in the service room, and causes the
indicator tablet to swing back again out of sight, and thus shew to the person in
charge that the bell has been answered. Should a second bell ring while the first
is being answered the semaphore will shew which room has to be attended to, and
thus often obviate the necessity of the servant going back to the service room, in
many cases saving much time and trouble.
I will now proceed to describe in detail the semaphore, which forms the essential
feature of my invention. Figure 1 of the annexed drawings shews an elevation,
and Figure 2 a side view, of the apparatus with the outer case removed.
A is an electro magnet in a frame B. B. fitted by screws to the wooden back
board C C. It is provided with an armature D, attached to the frame B by a thin
plate spring E. The end of this armature terminates in a small catch or detent F,
of semicircular section (see Fig 2), which engages in a hooked slot G in the
semaphore arm H. The arm H is loosely pivoted at I to the frame B, and when
the armature D is attracted to the electro magnet, the detent F releases itself from
the slot G, and the arm falls by its own weight into the horizontal position, shewn
in dotted lines. The arm is also provided with a projecting extension piece K by
which it can be raised to its vertical position again. The actuating mechanism for
raising the arm consists of a rod L, sliding in a guide M, jointed at N to the end of
a lever arm 0. The lever, which is pivoted at P at one end, is forked at its outer
end, to allow of the rod L and spring Q being fitted between the branches. The
lowermost branch R (Fig 2) of the fork (i.e. the branch nearest the base plate) is
prolonged so as to pass under the guide S. and when the rod L is pulled down,
presses against the side of the projection K of the semaphore arm and thus raises
the arm into the vertical position again. The catch F then engages with the
hooked slot G and the rod L is brought up again by the spring Q.
The piece R, in being pulled down by the rod L, comes into contact with a flat
spring T, and thus completes a second circuit, by the spring Q and the wire U,
through the pendulum Indicator in the service room.
The action of the apparatus is as follows. When the visitor presses the contact
button, and rings the bell, the circuit is completed and a current passes through
(1) the bell in the service room, which it rings; (2) the indicator box, causing the
pendulum tablet to swing before its opening; and (3) the electro magnet A. The
armature D. is thus attracted, and releases the semaphore arm, which falls into its
horizontal position. When the domestic, after attending to the bell, raises the
semaphore arm by pulling down the rod L, the contact between the piece R. with
the spring T completes the second circuit, through the spring Q and wire U, the
current in which passes through the Indicator box and causes the indicator tablet
in the service room to swing back again out of sight, thus shewing to the person in
charge that the bell has been answered. The same happens should a second bell be
rung in the interim:
Having now particularly described and ascertained the nature of my inven-
tion, and in what manner the same is to be performed, I declare that what
I claim is
1. A Semaphore Indicator for electric bell systems, substantially as and for the
purposes hereinbefore described and illustrated in the accompanying drawings.
2. A Semaphore Indicator for use with Electric Bells, wherein the mechanical
act of replacing its arm completes an electric circuit, and thereby reverses the
indicating tablet for shewing the bell rung.
001 1.. of Anmil 188K