MECHANICS AND USEFUL ARTS. 27 



adding to its strength, the power to resist impact is, within certain 

 limits, also increased. Hence, it follows that weight is an important 

 consideration in structures exposed to concussions." 



CAST-IRON SLEEPERS FOR RAILWAYS. 



A SERIES of experiments has been carried out by Mr. P. W. Bar- 

 low, from which he has been led to recommend the substitution of 

 cast-iron in place of wood in laying the substructure of permanent 

 ways, as the only means of preventing those irregularities of surface 

 which cause blows to be given by the engine, that are not only annoy- 

 ing to the passengers, but further are more and more rapidly destruc- 

 tive to the way and to the carriages, as well as wasteful of the loco- 

 motive power and mechanism. Mr. Barlow finds it to be a mistake, 

 that a partially soft elastic material, such as wood, is requisite to smooth 

 and easy motion ; the more rigid, and level, and polished the surface, 

 the easier has he found the traction, and the better suited at least to 

 railway transit. Cast-iron sleepers in halves, with half-chairs fitting 

 the rail, and bolted together, so as to avoid the use of the key, is 

 that construction of substructure to which experiment has led him to 

 yield the preference, from the facility with which it is laid, from the 

 perfect joint which it gives, and the security from breakage in the 

 event of getting off the line. The point of the meeting of the plates 

 is situated between the chairs, so that the bolts act under a spring 

 which destroys all liability of loosening, to which he has not found 

 any tendency. London Builder, Feb. 



PREVENTION OF DUST AND SMOKE ON RAILROADS. 



MR. N. GOODYEAR of New York has invented an apparatus for 

 preventing passengers on railroads from being annoyed by dust and 

 smoke. On the roof of the car a number of ventilators are arranged, 

 so as to allow the air to pass freely into the car when it is in motion. 

 The mouths of these ventilators are covered with a fine wire cloth, 

 through which the air circulates freely, but \vhich effectually stops all 

 cinders and other dirt. In each window of the car is placed a sash of 

 blinds, constructed of plates of glass four inches wide. These blinds 

 are so arranged that they are all moved by a connecting-rod, in the 

 same manner as ordinary window-slats are opened or shut. The air, 

 coming through the ventilators, passes with a gentle current out of 

 the blinds, or "car-dusters," as they are called, the outward current 

 thus formed effectually preventing the entrance of a particle of dust 

 into the car, and the outside current, formed by the motion of the car, 

 carrying the dust to the rear. Besides entirely excluding the dust 

 and smoke, it is claimed that this invention, which does not at all ob- 

 struct the view, will ventilate the cars, and, by stifling the noise, ren- 

 der conversation much easier than at present. An apparatus of this 

 sort has been applied to a car on the Hudson River Railroad. New 

 York Tribune. 



