672 PROCEEDINGS OF SECTION H. 



The three wire instruments in use in many parts of Great Britain 

 and on portions of the New South Wales lines provide separate in- 

 dications for these three conditions, but the single wire instrument 

 in use in New South Wales and the Winter block instrument in use 

 in Victoria and South Australia provide only two. Hence, as these 

 instruments are worked, there is and can be nothing to distinguish 

 between conditions (b) and (c) above mentioned, though, of course, 

 the signal register-book would give the desired information. In the 

 writer's opinion this involves an unnecessary and undesirable tax on 

 the signal man's memoiy, and must at times lead to confusion. 



As regards single line working, the Board of Trade i-equires 

 (except in the case of lines worked by one engine) the use of the 

 block telegraph system combined with the train-staff and train-ticket 

 system or, as an alternative, the electric staff or tablet system. As 

 far as the writer can gather, in Victoria and New South Wales single 

 line working is carried out in compliance with the above systems, 

 with the exception that in localities where the traffic is very light the 

 train-staff and train-ticket system is used without the block telegraph 

 system. In those localities where the staff stations are connected by 

 telegraph or telephone, advice is given by that means as to arrival 

 and departure of trains, but the rule provides for the departure of a 

 train before advice has been received of the previous train reaching 

 the station in advance, if such previous train has left at least ten 

 niinutes and the driver of the following train is given a " notice of 

 train ahead," thus introducing the principle of the permissive system. 



Whilst the general outlines of single line working by electric 

 staff in Great Britain and Australia are identical, the following 

 important difference is to be noted: — In Great Britain, on a single 

 line, " line clear" means that the station in advance is clear for a 

 quarter of a mile past the home signal, or at least up to the starting 

 signal, and if it is desired to let a train enter a single line section 

 whilst the station in advance is blocked, it must be on the " section 

 clear, but station" or " junction blocked " signal, always provided 

 that the section is one Avhere such a signal can be given, otherwise 

 the train would be held back until the "' line clear" signal coidd be 

 properly given. Neither in Victoria nor New South Wales is the 

 "section cleax^, but station" or "junction blocked" signal given in 

 single line working, but in Victoria, on single lines, "' line clear" 

 means only that the line is clear up to the home signal, whilst in 

 New South Wales it means that if the station in advance be a cross- 

 ing terminal or junction station the line is clear to the " home signal " 

 only, whilst if it be not one of these, that the line is clear at least a 

 quarter of a mile past such home signal. 



In Soutli Australia single lines aie worked without any staff 

 whatsoever, the Winter block instruments being used. The writer has 

 not had the opportunity of inspecting these instruments, but, pre- 

 sumably, they are arranged so that " line clear" cannot be given 

 from both ends at the one time. In any case, the instrimient does 

 not seem a desirable one, as a station-master might in error allow a 

 train to depart without having received "line clear" for it, and, in 

 fact, when permission has been given for a train to depart from the 

 opposite end. With single line working a driver is entitled to a 



