48 ANNUAL OF SCIENTIFIC DISCOVERY. 



Kiew, is the largest work of the kind in Europe, being 3,503 feet 

 in length. Van Nost. Eng. Mag, 



THE BROADWAY UNDERGROUND RAILWAY 



Commences at the foundation lines of the splendid marble 

 building on the corner of Warren Street, and extends in a curve 

 directly down Broadway. The lower terminus is intended to be 

 at the South Ferry; but the present operating section only ex- 

 tends a little below the City Hall, near to the north end of the 

 new post-office premises, a distance of some 300 feet. 



The bed of the railway is 21 feet below the surface of Broad- 

 way, and the diameter of the tunnel 9 feet. The passenger car 

 is about the same size as the ordinary street cars. It is very 

 tastefully fitted up, brilliantly lighted, and has seats for 22 per- 

 sons. It is propelled by the atmospheric system ; that is to say, 

 by means of a strong blast of air which is supplied to the tunnel 

 by a gigantic blowing-machine. 



The whole operation is described as being exceedingly simple 

 and effective. The visitor enters at the corner of Broadway and 

 Warren Street, descends a few steps to the waiting-room, an 

 elegant apartment, but wholly under ground, at the end of 

 which is seen the mouth of the tunnel and the car. On taking 

 seats in the car, the conductor closes one of the doors and 

 touches a telegraph signal, when the car immediately begins to 

 move around the curve, and travels rapidly down Broadway. On 

 reaching the lower end of the tunnel, the car moves instantly 

 back again to Warren Street, then down Broadway again, and so 

 on. The air is so clastic that the changes of motion in the car are 

 effected with exceeding gentleness, and are almost imperceptible 

 to the visitor. 



The car is run by telegraph ; that is to say, the wheels of the 

 car, at certain points on the route, press a telegraph key, sending 

 a signal to the engineer, who turns a valve and thus reverses the 

 air-current, without stoppage of the machinery. 



The aeolor, or blowing-machine, by which the air-current is 

 produced, consists of a pair of great wings, geared together, and 

 turned by steam. It is capable of discharging 1 100,000 cubic feet 

 of air per minute, or enough to fill the interior of 3 3-story city 

 dwelling-houses. 



The south end of the tunnel is provided with a lateral air-shaft, 

 which opens in the grass-plot of the City Hall Park. The air-cur- 

 rent thus traverses through and through the tunnel, the atmos- 

 phere of which is thus kept pure and fresh. 



During the construction of the tunnel the entire travel of Broad- 

 way, omnibuses, carts, hacks, and other vehicles, in endless pro- 

 cession, passed on as usual, directly over the heads of the work- 

 men. They were safely protected within the sides of an immense 

 boring-machine, by which the bowels of the street were excavated. 

 It is pushed forward into the earth by means of powerful hy- 

 draulic rams ; and as fast as it advances the masonry is built up 

 within its rear. 



