IMPROVE- MENTS IN APPARATUS FOR DETECTING AND DETAINING THIEVES, AND INDICATING THE PRESENCE OF FIRE
Year: 1863

page_text: PROVISIONAL SPECIFICATION left by James Craig at the Office of
the Commissioners of Patents, with his Petition, on the 4th March
1863.
I, JAMES CRAIG, of Weston Park, Shipston-on-Stour, in the County of
Worcester, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN APPARATUS FOR DETECTING AND DETAINING THIEVES, AND INDICATING
THE PRESENCE OF FIRE," to be as follows:-
This Invention relates to a peculiar arrangement and combination of
apparatus governed by an electric current for detecting the fraudulent tam-
pering with safe or other doors, and for detaining the person so engaged, part
of which apparatus also serves as an indicator of fire.
In applying this Invention to a safe, for example, it is proposed to place
inside the safe or in any other convenient place a Grove's or other battery,
one pole of which is connected by an insulated wire with an electro-magnet
situate immediately beneath the floor or support of the safe, or in any other
convenient locality. The armature of this magnet is fitted to one end of a
lever, the other end of which serves (so long as the lever is not acted upon by
the magnet) as a stop for a catch lever, which is made to support a trap door

page_text: constructed in the floor immediately in front of the safe. So soon as a circuit
is established through the electro-magnet, which takes place on any attempt
being made to raise the guard or shield of the keyhole in the safe door, the
catch lever is released, and the trap door being no longer supported instantly
falls, depositing the thief in a suitable vault or chamber below the floor.
From the electro-magnet above referred to a wire leads to one of two terminal
screws on an electric bell or alarm, the second screw being connected with
another wire, from which two branches lead, the one into the top of a tube
partially filled with mercury and contained inside the safe, and the other to
an insulated knob in the front portion of the top of the safe, but inside the
same. The wire from the opposite pole of the battery passes first round an
electro-magnet contained inside the safe, which acts when excited upon a
hooked lever, and forces its hooked end through a hole in the bolt of the lock,
so as to effectually prevent its being stirred until the circuit is broken. Two
branches also lead from this wire, the one entering the mercury in the tube
above referred to, and the other leading to an insulated knob at the bottom of
the safe corresponding to the knob at the top above referred to. Inside the
door of the safe there are two insulated springs, which, when the door is
closed, respectively bear against the top and bottom knobs inside the safe.
Each of these springs is connected by a wire with corresponding insulated
springs disposed on each side of the keyhole. The keyhole itself is closed on
the inner side of the door by a guard plate or shield, which must be elevated
before a key or other instrument can be inserted into the lock. On raising
this shield or guard plate it is brought in contact with the two last-mentioned
springs, and establishes an electric circuit throughout the entire apparatus, the
result of which is the simultaneous falling of the trap door, the ringing of the
alarm bell, and the securing of the bolt of the lock. When fire is applied for
the purpose of destroying the safe or lock the mercury in the tube rises until
it comes in contact with the wire above it, and consequently establishes a
circuit, which causes the alarm bell to be rung. Any well-known construction
of electric alarm may be employed, but the arrangement I prefer consists of a
box or barrel spring in connection with a spur wheel, which is in gear with a
small pinion on the centre of a pair of rotating arms or beaters provided with
a hinged hammer head on each end, which strike against a bell as they rotate.
A hooked detent engages into the teeth of the spur wheel so long as the
apparatus is not in action, but when a circuit is established this detent is
removed from the teeth by being acted upon by an electro-magnet in the
circuit, whereupon the bell commences to ring, and continues so to ring

page_text: until the barrel spring is run down. A small "switch" or marked
break contact lever is fitted to the alarm, the turning of which breaks
the circuit and prevents the apparatus from acting when not required to
operate.