A New or Improved Apparatus for Giving and Regulating the Duration of an Audible Signal on the Rise Fall of Temperature in Sick Rooms or other Places.
Year: 1885

page_text: A New or Improved Apparatus for Giving and Regulating the
Duration of an Audible Signal on the Rise
Fall of
Temperature in Sick Rooms or other Places.
We CHARLES LINDLEY of 34 Englefield Road London, N. in the County of
Middlesex, General Merchant, and FRANCIS JOHN MUDFORD of The Arrow
Electrical Works, Jackson Road Holloway in the County of Middlesex, Electrical
Engineer do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement:―
Our Invention relates to an apparatus which is intended more particularly for
use in hospitals and other places where it is desirable to maintain the temperature
constant or within certain limits.
According to one mode of carrying out our Invention, we employ a thermometer
connected up in the circuit of an electric cell or battery and bell in such a manner
that on the temperature falling below a certain limit, contact is made, thus
completing the circuit, and ringing the bell. In this circuit we interpose a switch
operating with a butt contact in such a manner that by the act of turning a milled
head, knob or handle in one direction or the other the spindle carrying one of the
contacts is screwed out or in, that is to say from or to a fixed contact, and thus
breaking or completing the circuit at the switch. In the normal condition of the
apparatus when in use, the switch is in its inward position with the circuit
uninterrupted thereat so that the audible signal is given as soon as the temperature
falls below the given point. When, however, the signal has continued a sufficient
length of time to attract attention, it may be instantly interrupted by the act of
turning the switch so as to break the contact thereat, and thus obviate the
inconvenience to the occupants of a sick chamber which would be occasioned by the
continued ringing of the bell.
Similarly, the apparatus may be caused to operate on the rise of temperature, or
one and the same apparatus may be arranged to operate both for rise and fall of
temperature, as will be obvious without further explanation.
The cell or battery is by preference enclosed in a case with the bell, switch and
thermometer mounted on the outside thereof, the whole being self-contained and
brought within a small compass so as to be readily carried in the hand.

page_text: It is preferred, also, to so arrange the parts of the switch that the two (platinum)
contacts shall be enclosed in a dust proof chamber formed by an attachment to the
case and by a cast metal cover through which the operating screw carrying the
movable platinum contact works. This cover itself forms part of the circuit, being
attached to the case by studs screwed and soldered to the cover, to one of which
studs one of the conducting wires is soldered, the other conducting wire being
soldered to another stud passing through the case, and which carries the fixed
platinum contact.
And in order that the said Invention may be perfectly understood, we shall now
proceed more particularly to describe the same, and for that purpose shall refer to
the several figures on the accompanying sheet of drawings, the same letters of
reference indicating corresponding parts in all the figures.
Figure 1 of the accompanying drawings represents a back elevation of the case
containing and carrying the whole of the apparatus, Figure 2 is a plan and
Figure 3 a front perspective view of the same, the case being shewn with the door
open in all these figures for the convenience of illustration. Figure 4 is a hori-
zontal section (drawn to a larger scale) of the switch herein before referred to,
shewn attached to the case, and Figure 5 is an end. view of the switch.
A is the containing and supporting case (by preference of wood) consisting of
the bottom a, forming a base for the whole, the top 6 to which is attached a
handle B for the convenience of carrying the apparatus in the hand, the back c
bearing the thermometer C which automatically starts the audible signal, the side d
bearing the switch D, the side e which in this example is unoccupied, and the
door carrying the electric bell F and the usual mechanism F' appertaining
thereto, the door serving to close the case A which contains the cell or battery E,
shewn for convenience in dotted lines in Figure 3, so as to admit of the connections
being indicated diagrammatically.
The thermometer C (the rise of the mercury in the limb C' of which indicates
increase of temperature and in the limb C2 fall of temperature) is permanently
connected to the switch by a wire 1, which extends from the thermometer at g to
a stud h (Figure 4) to which it is soldered, the said stud being in electrical
connection with the movable platinum contact of the switch as fully hereinafter
described. To a stud i bearing the fixed platinum contact of the switch is
soldered a wire 2 leading to one pole of the cell or battery E, the other pole of the
cell or battery being connected by a wire 3 with the bell mechanism F¹, from
which another wire 4 is taken to a contact g¹ arranged on the limb C of the
thermometer C at the height corresponding to the degree at which it is desired the
signal should be given.
The movable platinum contact k of the switch is carried on the operating screw 7,
provided with a milled head, knob or handle m. This screw works through a cast
metal cover n, tapped for its reception and attached to the side d of the case A by
studs h, h', screwed and soldered to the cover n, a plate o of ebonite or other
suitable insulating substance, being interposed between the cover n and the side d
of the case, through which insulating plate o and the said side d, passes the stud i
bearing the fixed platinum contact k¹ as before mentioned. The cast metal cover n
thus itself forms part of the circuit, which is closed at the switch when the movable
contact abuts against the fixed contact kl, and open when it is separate there-
from; the cover n, moreover, constituting with the insulating plate o a dust proof
chamber which encloses the contacts k, k¹.
In the normal condition of the apparatus when in use, the switch is in its inward
position, that is to say with the contacts k k¹ together, and the circuit is closed at
the switch. The circuit is, however, broken in the thermometer at g¹ until on the
temperature falling the mercury rises to a sufficient height in the limb C of the
thermometer to complete the circuit at g', when the bell will be rung. When
the signal has continued a sufficient length of time to attract attention, the circuit
is broken at the switch by the act of unscrewing the screw 7 by the aid of the
milled head, knob or handle m (the head of the screw preventing it from being

page_text: screwed too far out) and the action of the bell ceases. The temperature is again
raised and the apparatus is restored to its normal condition for use by the act of
screwing up the screw 1, the circuit being again broken at the switch after the
signal has been repeated and maintained for a sufficient length of time, consequent
on the temperature again falling below the fixed limit, and so on in succession as
long as the apparatus is required for use.
When the apparatus is required to operate on the rise of temperature, a contact
is provided at the requisite height on the limb C¹ of the thermometer C, and a wire
is taken therefrom to the bell mechanism, or the two contacts in the thermometer C
may be used in one and the same apparatus, which will then operate both for rise
and fall of temperature, as will be obvious without further explanation.
Having now particularly described and ascertained the nature of our said
Invention, and in what manner the same is to be performed, we declare that what
we claim is
1st The combination with an electric cell or battery, an electric bell, and a
thermometer automatically completing the electric circuit on an undue rise or fall
of temperature and thus giving an audible signal, of a switch operating with a
screw action to make and break a butt contact, and thus regulate the duration of
the signal, substantially as hereinbefore described.
2nd The new or improved apparatus for giving, and regulating the duration of.
an audible signal on the rise or fall of temperature in sick rooms or other places,
such apparatus consisting of the electric cell or battery, the electric bell, the
thermometer automatically completing circuit as set forth, and the switch D
operating as set forth, with its contacts enclosed in a dust proof chamber, completed
by the cover n forming part of the electric circuit, and the whole of the said parts
being carried and contained on and in the portable case A, all substantially as
hereinbefore described and illustrated in the accompanying drawings.