54 ANNUAL OF SCIENTIFIC DISCOVERY. 



tlie old projuflices afrainst it may be removed, while its true 

 merits are openly and universally acknowledged. 



HOLLOW STAY-BARS FOR STEAM-BOILERS. 



The safety often of many pei-sons depends on the efficiency of 

 the stay-bars of a steam-boiler; but too often their importance is 

 not suliieiently recognized, or tiiey are weaker or less numerous 

 than they should be, that a little additional i)rofit may be made by 

 tht^ l)oih'r-maker. A btiil greater source of danger exists when 

 tiiey have been used, Ijut have become so corroded as to be prac- 

 tically worthless; which, from thoir position, is very likely to be 

 tiie case, and without its being j)robal)le, or jjcrhaps possible, to 

 discover the change they have undergone, A very simple and 

 elYeetive way of making them ])roelaiin tlieir own inefficiency is 

 now in use on the Nortliern Railway of France. They are made 

 with a small l^ore from end to (md, and thus when one of them 

 gives way, or is seriously corroded, the steam or water escapes 

 through in such a way as infallibly to attract attention. To pre- 

 vent their being stopped up by dust, etc., their extremities, where 

 not otherwise protected, are loosely closed with wood, etc., which 

 is easily liiown out by the escaping steam or water. From the 

 smallness and position of the bore, which is exactly in the centre, 

 the rod is scarcely at all weakened by it, but the necessary strength 

 may be secured by a very slight augmentation of its diameter. — 

 Intellectual Observer, April, 1866. 



MONT CENIS RAILROAD.— CENTRE-RAIL SYSTEM. 



On account of the long time which must yet be consumed be- 

 fore the Mont Cenis Tunnel is finished, — four and a iialf mih^syet 

 remainnig to be execut(id, — it is proposed to place a temporary 

 track over the summit of the mountain. An experimental line of 

 one and a fourth miles has been constructed on the most difficult 

 ))ortion of the route. By the report of Capt. Tyhir, of the Royal 

 Engineers, this distance is ascended in eight and a half minutes 

 with a load of sixteen tons, though the average grade is as steep 

 as one in thirteen, and at a maximum of one in twelve. The 

 plan adopted toobtain adhesion is an arrangement of horizontal 

 drivers biting on a central rail. This plan, though regarded as 

 new in Europe, was long ago patented and used in America. — 

 Journal of the Franklin Institute, Nov., 1865. 



A paper on the same sulyect was communicated to the British 

 Association, in 18GG, by Mr. J. B. Fell. After alluding to the 

 various difficulties presented to the advance of railways by moun- 

 tain ranges, and the efforts made to overcome them, it was stated 

 that the use of the centre-rail Avas first thought of by Messrs. 

 Vignolles and Ericsson, in 1830, and proijosed to be applied to the 

 inclines on the Manchester and Liverpool Railway ; but it was not 

 put into opei-ation. In ignorance of what was then done. Baron 

 Leguir, in France, the writer, and others, also applied their minds 

 to a solution of the problem of constructing railways over steep 

 gradients. It was not till Mr. Brassey and the writer built a 

 centre-rail engine, and laid down a length of line on that plan on 



