INDUSTRIAL PROGRESS FOR THE YEAR 1871. xxix 



ed, on the 26th of December, 1870, although it was not actu- 

 ally used for the passage of trains until within the past year. 

 It may be a matter of interest to mention that the total 

 length of the tunnel is 13,365 yards, the highest summit of 

 the Alps above it being 5307 feet. 



Various forms of artificial stone have been brought to no- 

 tice, some intended to resist air and water, while others are 

 recommended for furnaces and other localities, requiring fire- 

 proof material. Among them may be mentioned the selenitic 

 mortar of Colonel Scott, the Sorel cement, the Coignet con- 

 crete, the Dinas stone, etc. 



The dangers of railway traveling have been alleviated by 

 the introduction into practical use of various forms of brake, 

 in which air and steam are used as the agents to stop trains 

 at high speed in a very short time. Improved indicators of 

 velocity have also been devised. 



The idea of constructing railways of narrow gauges for 

 mountainous regions and those having a comparatively lim- 

 ited traffic has been a popular one, and numerous lines have 

 been commenced both in this country and in the Old World. 

 The average width selected seems to be about three feet six 

 inches. 



The views of experts in regard to the supposed deteriora- 

 ting eflect of cold upon iron seem to have undergone a change 

 from the results of the experiments of Mr. Brockbank and 

 Mr. Joule, of Manchester. From these it would seem that 

 iron is actually made stronger instead of weaker by cold, 

 while the unmistakable fact of the greater tendency of iron 

 rails, wheels, and axles to break during cold weather is ex- 

 plained under the theory that the frozen soil is rendered 

 more rigid and unyielding, and that the shock of impact is 

 consequently much greater than where the soil possesses the 

 elasticity attendant upon warmer weather. 



The war between France and Germany, happily termina- 

 ted during the past year, furnished an opportunity for test- 

 ing various forms of military weapons, every variety having 

 been brought into use and experimented upon during the 

 campaign. The mitrailleuse and the Gatling gun, while not 

 possessing the power of attack and defense attributed to 

 them by their advocates, have yet proved serviceable in cer- 

 tain conditions, and are likely to be adopted in future war- 



