MECHANICS AND USEFUL ARTS. 57 



further security against the wedges shaking loose, that they may be 

 driven in with sal ammoniac, and thus ensure an immovable and per- 

 manent line of road. 



IMPROVEMENTS IN VENTILATING RAILROAD CARS. 



Fame's Ventilating Car. The principle upon which this improve- 

 ment is founded, differs from that of the ordinary systems of ventila- 



V 



ting cars in this respect : that, with Mr. Paine's apparatus, the currents 

 of air which pass through the car enter at the top, and pass out through 

 the windows at the side. Hitherto the open windows of cars have 

 been relied upon for supplying fresh air, and the ventilators in the 

 top of the car have been exhaustive, designed to draw out the impure 

 air. 



The car to which this system is applied is built like any other car, 

 with the exception of the windows, and these form an important part 

 of the apparatus. Instead of opening like a common house window, 

 they open like a door, and each one is opened, say two inches, the 

 opening looking outward, in the opposite direction to which the car is 

 running. The car being set in motion, the friction of the external air 

 upon the points where it comes in contact with the air within the car 

 has the tendency to exhaust the latter, or exercise a traction, if we 

 may so express it, upon the whole volume that the car contains. The 

 second part of the invention has for its object, the supplying of 

 external air to the constantly exhausting volume within, free from 

 dust, and in the proper quantity. This is done by apparatus fixed 

 upon the roof of the car. Suppose a tin pan full of water upon the 

 roof, with an opening into the car around and beneath it. Over this 

 tin pan place a lid, made up of short, aggregated tubes, which stand 

 perpendicularly to the water. Now adjust it so that all the air that 

 enters the car at this point, shall enter through this lid, or screen of 

 tubes, and set the car in motion. The air rushes in through the tubes 

 and must take its direction perpendicularly to the water, striking the 

 surface of the water at a right angle, and projecting and depositing 

 upon its surface the dust for the time suspended in it. The air itself 

 passes over the edge of the pan, the lid not coming down to the edge, 

 and enters the car pure. The roof of the car is supplied with a series 

 of ventilators, each of which has wings attached to receive as much 

 air as possible. The air entering these, it will be observed, is not 

 strained of the dust and cinders it contains by passing through the 

 water, but the whole mass of air merely comes in contact with the 

 surface of the water, before it passes over the edge of the pan, and 

 thus deposits its dust, or the dust, by its superior weight, possesses a 

 momentum which carries it through the current as it shifts to pass 

 over the pan, and throws it upon the water before the new current 

 changes its direction. 



The advantages of the car are obvious. A fine ventilation is 

 secured, and all dust is obviated. Both these advantages are invalua- 

 ble, but added to these is the advantage of stillness in the car, all the 



