546 Progress in Science. [October, 



whole process. The lime, by this means, is enabled to take twice as much 

 sand as when slaked. Experiments made against Portland cement, showed 

 that while a joint made with the latter, after standing fourteen days, separated 

 with a weight of 56 lbs., the cement in most cases coming clean away from 

 the tiles which were joined together by it ; the selenitic mortar, composed of 

 1 part lime to 5 of sand , under precisely similar conditions, required a 

 weight of 158 lbs. to overcome adhesion, and then the fracture took place com- 

 pletely through the cement, half remaining on each side. 



Narrow Gauge Railways. — The great revolution in the present day as 

 regards the means of locomotion, consists in the adoption of a narrower gauge, 

 and cheaper class of railway than that employed on the first introduction of 

 railways. The rare occurrence of first-class railways proving remunerative 

 has rendered it more and more difficult to raise the necessary funds for their 

 construction, at the same time that the demands for an extension of railway 

 communications have rapidly increased, and so, notwithstanding the opposi- 

 tion to any such change by many leading members of the profession, narrow- 

 gauge lines having steeper gradients and sharper curves than were formerly 

 considered admissible may now be considered as an accepted necessity. In 

 India, a gauge of 3 feet 3! inches has been adopted after very deliberate con- 

 sideration by a committee appointed to report on the subject, and this will 

 speedily become the standard gauge of the country. Australia, Tasmania, and 

 New Zealand are all following in the same course. In Russia, the 3 feet 6 inch 

 gauge has been definitively accepted, and an extensive system of lines on that 

 gauge is now under construction. In Egypt the same width is to be adopted ; 

 whilst in the United States more than 2000 miles of narrow-gauge lines are in 

 actual progress, or about to be commenced. California is organising railways 

 on a reduced gauge in all directions, Canada is following in the same direc- 

 tion, and even for Prince Edward's Island contractors have been invited to 

 tender for the construction of a 3 ft. 6 in. line from Casumpec to Georgetown, 

 a distance of 120 miles. Light railways, and narrow gauge railways, are too 

 often confounded together as being one and the same thing, whereas they are 

 in reality totally distinct. The former subject has been recently brought 

 before the Civil and Mechanical Engineer's Society, in a paper read by Mr. 

 William Lawford, M. Inst. C.E. Light railways may often be of the same 

 gauge as our first-class lines, only of a different construction. As feeders to 

 main lines they will doubtless prove valuable adjuncts to the existing system 

 of the country, especially in those districts where the natural features of the 

 land would otherwise require expensive works. One important feature in con- 

 nection with light railways must not be lost sight of, viz., that it would be 

 impossible to carry on them a large and rapid passenger traffic, such as is now 

 the case with the main lines of the country. A large and rapid traffic means 

 heavy engines, heavy rails, &c. ; but for an omnibus or light goods traffic, a 

 light railway, with light permanent way materials, light engines, &c, might be 

 made with great advantage, not only to the travelling community, but also to 

 shareholders. The author then proceeded to give a description of a short 

 line of " light railway " which had lately been constructed for the Duke of 

 Buckingham and Chandos, by means of which the Duke's estates at Wotton 

 are brought into connection with the Aylesbury and Buckingham Railway at 

 Quainton. This line (4 ft. 8£ in. gauge) is six miles in length, with a branch 

 of one mile and a half. It is throughout eminently a line of light works, and, 

 with few exceptions, a surface line, the highest embankment being 12 feet, and 

 the deepest cutting 10 feet. There are no road-bridges, the turnpike and 

 other roads being crossed on a level. The rails are bridge-rails, weighing 

 30 lbs. to the yard, and are secured into longitudinal creosoted timbers, 

 6 feet 6 inches long, by means of fang-bolts ; there are transoms 4 inches by 

 4 inches at every 12 feet, kept in their places by a wrought-iron tie-rod, f inch 

 in diameter. The ballast is 10 feet wide, and is 6 inches to g inches thick 

 under the bottom of the timbers. The line is only partially fenced, the existing 

 hedges being utilised for that purpose. The estimate for the works is only 

 ^1400 per mile, exclusive of the cost of land. A paper on the subject of 

 " Railway Gauges " was read by Mr. R. F. Fairlie, before Section G of the late 



