MECHANICS AND USEFUL ARTS. 115 



described, the tube can be at once divided at the desired point by 

 merely bending it, or, if the piece to be cut off is very short, all 

 that is necessary is to hold the tube above the flanie of a lamp or 

 candle, when it will at once divide at the point where the diamond 

 cut was made. M. Ducomet states that it is absolutely necessary 

 that the rod should be covered with cotton or similar soft material, 

 or that otherwise tubes cut in this way gauge-tubes for instance 

 will subsequently break when in use. The instrument is par- 

 ticularly adapted to cutting gauge-tubes. 



SINGLE RAIL TRAMWAY. 



Mr. J. W. Addis, C.E., is experimenting in India on a new 

 form of single rail tramway. The vehicles used, in addition to 

 the ordinary wheels, have a pair of flanged wheels, one behind 

 the other, running on the single rail, which is laid at the centre 

 of the track. The flanged wheels are adjusted by a screw so as 

 to take all the weight off the ordinary wheels, without lifting 

 them much above the roadway. An experimental line has been 

 laid, in part at an incline of 1 in 40, and along this a pair of 

 bullocks draw a load of 3 tons. The advantages claimed for the 

 system are : first, a very great diminution of power expended 

 in hauling as compared with traction on common roads ; sec- 

 ondly, that the cost of construction is only one-half that of an 

 ordinary tramway with 2 lines of rails. A tramway or railway 

 on a similar principle was, we believe, tried some time ago in 

 France. Science Ileview, Oct., 1870. 



< 



VENTILATION OF COAL MINES. 



Mechanical ventilation in coal mines is steadily gaining 

 ground on the older plan of producing a draught in the up-cast 

 shaft by means of a furnace. Mr. D. P. Morrison recently read 

 a paper on the subject before the North England Institute of 

 Mining Engineers, at which he stated, that in the deepest Eng- 

 lish coal mines, mechanical ventilation would show an economy 

 of 35 to 40 per cent, over furnace ventilation. After discussing 

 various arrangements of mechanical ventilators, he gave the pref- 

 erence to the Guibal centrifugal fan. Science .Review, Oct., 1870. 



PETROLEUM FOR HEATING LOCOMOTIVE BOILERS. 



Two engines on the Strasbourg line have been fitted with M. 



^j tj 



Deville\s furnaces, and are employed in the goods traffic. The 

 consumption of oil in the engines drawing heavy trains is stated 

 to have been from 3 to 5 kilogrammes for every kilometre trav- 

 ersed, or from 8 pounds to 12 pounds for every two-thirds of a 

 mile. The oil is said to be very completely burned, and there is 

 no smoke and consequently no waste. Another advantage 

 claimed is, there being no sulphur in the oils the atmosphere of 



