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April 1, 1868.] THE CIVIL ENGINEER AND ARCHITECT’S JOURNAL. 97 by Mr. Preece to some of the South Western trains, as this will give a fair idea of all the other systems. Mr. Preece’s apparatus consists of a small sulphate of mercury battery, which together with a very simple arrangement for causing the electric currant to ring a small, shrill, trembling bell, is enclosed in a rough wooden box; this box is fitted with metal hooks, which serve to complete the electrical connection when the box is hung up against a partition of the guard’s van ; a single wire coupled, passes underneath the carriages, along the whole train, the coupling is formed by an ordinary stout galvanized iron eye placed over a brass hook, against which it is kept in firm contact by a strong bent steel spring. Mr. Preece makes use of a double set of couplings in such a manner, that the possibility of failure in this respect is very slight, if not altogether avoided. The coupled wire is main tained in electrical equilibrium as before explained, and when this equilibrium is destroyed by placing the train wire into communication with the earth, through the iron work of the carriage, the current now established, passing through an electric magnet, acts upon the hammer of the signal bell. In order to prevent the oscillation of the train, having any effect upon the hammer, a small bent lever stop bar is used, which in its normal state keeps the hammer free of the bell : this bent lever stop bar is also an armature of the electro magnet, so that when the current is established, the lower vertical arm of the bent lever is first drawn to the magnet, and the upper horizontal arm being raised, allows the hammer to act freely. A small steel spring assists in keeping up the vibratory action, and the bell continues to ring so long as the electric current is permitted to pass ; all that is necessary therefore, is a small apparatus in each compartment of each carriage, by means of which a passenger can at any time by tnrning or pulling a handle, bring the train wire into connection with the earth, and so completing the electric circuit, sound the bell in the guard’s van. In Mr. Preece’s system, the handle to be operated on in each compartment is protected by a glass covering, which has to be broken before the apparatus can be used. The object of this expedient is to prevent as much as possible any mis chievous tampering with the apparatus. The broken glass affords an easy means of detection, in case the signal has been wantonly used. In practice it has been found an unnecessary expense and complication of the apparatus to make use of any exterior sight signal, liberated by the same action that causes the bell to sound, for in the case of any wrong use of the apparatus, the broken glass, or any other similar expe dient employed, is quite enough to indicate to the guard the compartment whence the signal has emanated, and in cases of real danger, the excitement among the passengers will enable him to perceive where his presence is required. The 10th and last class of expedients that we have to notice refers to windows, or openings of any kind, between the compartments, together with two or three proposals, too original in character - for anything like classification. Glass windows between the compartments have been adopted on many of our lines, and were also recommended by the French commissioners in their report, but it is obvious they afford but a very partial remedy for the evils we are pro posing to get rid of. As hitherto applied, they have been generally disliked, owing to their interference with the privacy ofpassengers. Perhaps a small piece of ground instead of trans- parent glass might get over this difficulty—passengers could be permitted to break this glass in case of danger, and so call the attention of the occupants of the adjoining compartment, but this calling of attention might not in many cases be of material value. Probably the use of glass openings between the compartments of a carriage would have a general salutary effect, as regards assaults, or other cases of a similar nature, and would act more as a deterrent, than in any other way, the expense of its application would moreover be very small. Among the decidedly original patented inventions for effect ing intercommunication in railway trains, we find one where the inventor proposes that the guard shall be provided with a crossbow, by the aid of which, he shall in case of danger fire projectiles to the front of the train, which projectiles shall violently explode in the air, and so arrest the attention of the engine driver. Another inventor proposes that a sounding target shall be fixed at a convenient height against the panel of the engine, and the guard, provided with a rifle or air gun, shall fire balls, which striking the target shall warn the engine driver, the latter is also to be provided with a similar gun, so as to fire when necessary at another sounding target, fixed on the top of the guard’s van. It is to be hoped, if either of the above systems came into general use, that our guards and engine drivers would be experienced marksmen, otherwise, the pastime might be attended with some danger to them selves, and the agricultural population generally. Another proposal is that the communicating line or wire, shall be attached to some part of the driver’s person, and another pro poser more boldly suggests that he should be subjected to a violent electric shock at the discretion of any passenger. Another inventor, in addition to a violent electric shock (which he kindly extends to the guard as well as to the engine driver) suggests also the “ simultaneous explosion of a small fire arm” in the van, and on the engine. Looking at the matter purely from a railway guard’s point of view, we cannot help thinking that this last expedient, would perhaps be a trifle more than was absolutely necessary to “ arrest our attention." These are but a few of the curiosities of the patent office, in relation to this subject. With regard to the whole question of intercommunication in railway trains, there are two things which we must b'e careful to estimate at their true value : first, the reality of the evils supposed to exist, and secondly, what proportion of these evils would be got rid of by the best system of intercommuni cation we are able to apply. We have seen that the question rests not so much on the mechanical difficulties of providing an efficient means of communication, as on the amount of benefit to be derived from it when compared with other and new evils that must be accepted together with any such system. Owing to the impossibility, as we are circumstanced, of enabling the guard to ascertain the cause of the signal before stopping the train, we run into a new element of danger, if the train is to be stopped immediately, and if it is only to be stopped at the next station, or fixed signal, we lose in a large measure the advantage of the communication. The French commissioners put it very clearly: they say “ Mais une reflex ion qui n’a pas ctd assez faite, et qui domine toute la question, e’est qu’avant de donner au voyageur le moyen d’appeler h lui les agents du train, il faut d abord donner h ces agents le moyen de se rendre aupres du voyageur, car on ne peut raisonnablement admettre qu’on arrete le train au premier signal emanent d’un compartiment. Il nous semble done, tout it fait premature de mattre les voyageurs en relation avec les agents du convoi; tant qu’ou n’aura pas resolu la question du controle de route.” Even with the most stringent legislative measures, there is always a strong probability that the means of communication would be made use of much more frequently than there would be any necessity for, and a certain amount of danger is always incurred by stopping a train out of course, even if the instructions given to the guard are to stop at the next station, or fixed signal, after receiving a summons, if this station be one at which the train does not usually stop. The number of accidents which might, humanly speaking, have been prevented, or their ulterior consequences mitigated, had some means of communicating with the guard of the train been provided, are not so many as might be supposed. During the last twenty years, the number of such accidents (spread over all the railways in the united kingdon) does not exceed from 45 to 50. No doubt it is to the interest of railway com panies to avoid accidents of all kinds taking place on their lines as much as possible, but the expense of providing a suitable system of intercommunication is by no means trifling; and the question still remains whether this cxpence may not after all be incompatible with the benefits to be derived from it, inasmuch as new and special dangers may be created of greater importance than those it is designed to guard against. We have constructed our railways without any special regard to the question of intercommunication in the trains ; we must therefore now be content with the best makeshifts ad missible. We do not see any reason why some electrical system should not be applied to all fast trains stopping at long intervals. On our southern lines there would be no impedi ment whatever, for no great interchange of rolling stock takes place. The northern expresses take up and put off carriages more than the local trains ; the difficulties here would there-
