TEA3N-SIGNALLING IN THEORY AND PRACTICE. 281 
One blow for every Up train or engine out. 
Two blows for every Down train or engine out 
Three blows for every train or engine in. 
In eacli signal-box a battery^ witb tbe proper number of 
cells^ is mounted^ a bell is set up^ and a riuging-key^ mostly 
detached from tbe bell for convenience of access_, is firmly 
fixed ; and one single telegraph wire is extended from station 
to station. The signalmen are not expected — they are not 
required — to look after their apparatus ; it is so simple that 
it almost takes care of itself; it cannot — indeed, it is essential 
that it should not — very easily get out of order. All they 
have to do is to make and enter the signals. 
Many Level crossings — roads used by the public — exist on 
the South-Eastern Railway. At all these there is a gate-keeper 
to open the gates or to close them against road-traffic, accord- 
ing as trains are at hand, or not. There is a crossing of this 
kind between Ramsgate and Margate. In the gate-house, as 
in all others, is a signal-bell. The gate-keeper is not provided 
with a battery, and has no power to send signals ; but the bell 
is so placed in the circuit of the telegraph wire that every 
signal, passing between the stations, rings this intermediate 
bell, and warns the gate-man in language that cannot fail to 
be heard and understood, of the trains, up and down, that may 
be approaching. These are called hearing-bells and are 
used for a variety of purposes. At Margate, for instance, and 
many other places, the signalling is done in a box at- some 
distance from the station ; but in order that the station autho- 
rities may know what is going on, and when trains are at 
hand, the current of electricity is not allowed to enter the earth 
until it has passed through a hearing-bell on the Margate 
platform. 
Next in simplicity to a signal-box at either end of a line 
with two pair of rails, is that at an intermediate station on a 
similar line. In this case the signal-box is provided with 
a pair of bells of different tones, or a bell and a gong or steel 
spiral. They are placed on either side of the box, each being 
at the side nearest to the station with which it is in com- 
munication. This arrangement may be seen in Plate XI., 
which represents the interior of one of Saxby and FarmePs 
signal-boxes, and of which more presently. The rules already 
given are equally in force here, and are carried out precisely 
in the manner above described. Trains come and go in 
either direction, stopping to take up and put down passengers, 
or running through, as the case may require; the signal- 
man by the sound of his bell, by the direction from which 
the sound comes, and by the number of blows heard. 
