1878 .] Continuous Railway Breaks . ! 7 
2. Automatic in action in the case of an accident, or of a 
division of a train, without any interference from 
engine-driver or guards, so that the break-blocks may 
— on the separation of the couplings between any 
two carriages — be self-applied on every wheel. 
3. Adapted to fly on, and not off, so that the blocks may 
be applied to and not released from the wheels, on 
failure of any of the parts, which would prevent the 
train from being started unless the couplings were 
complete and the whole apparatus in working order. 
4. Instantaneous in its application— say to full force 
within one second of time — when operated by engine- 
driver or guard, or when self-applied. 
5. Safe and simple in working — which does not necessarily 
imply simplicity in construction, as distinguished 
from risk and confusion in working. 
6. Moderate in cost, as compared with efficient durability 
of parts and easy maintenance. 
7. Capable of constant employment in the conduct of 
traffic, and not merely for employment in tests and 
in cases of emergency. 
8. Provided with indicators for engine-drivers and guards, 
showing at a glance the condition of the break-power 
and the continuity of the connections. 
The above conditions, coupled with those laid down by 
the Commissioners, that the break should be capable of 
bringing a train to a stand under any circumstances within a 
distance of 500 yards, seem sufficient for all practical pur- 
poses, and, if capable of being realised, not less than should 
be demanded in the interests of the safety of the travelling 
public. These conditions necessarily imply the use of a 
continuous break ; but before considering which of the nu- 
merous inventions at present in use mostly fulfils them, it 
may be interesting to describe briefly the principles attached 
to each of the best of them respectively. 
The several classes of continuous breaks at present in use 
may be divided according to the kind of power employed to 
actuate them. They may be classified as follows :■ — 1. The 
chain break. 2. The hydraulic break. 3. The vacuum 
break. And 4. The air break. It is not pretended here to 
give descriptions of every kind of break that might be in- 
cluded under the above headings severally, but only of those 
which are unquestionably the representatives of each class, 
in consequence of their undoubted superiority, so far as has 
been hitherto ascertained by aCtual experience gained in 
the constant use of them in general work on lines of railway. 
