MECHANICS AND USEFUL ARTS. 49 



The works of the Broadway Underground Railroad, taken 

 altogether, are of a most interesting: nature, well worthy of ex- 

 amination. The general plan of the Company is to lay a double 

 line of tubes from the South Ferry, under Broadway, the entire 

 length of the island, with a branch at Union Square, under Fourth 

 Avenue, to Harlem River. Such a road would have capacity for 

 carrying 40,000 passengers per hour. 



ROTARY PUDDLING FURNACES. 



A number of puddlers, of this character, have, for some time, 

 been in successful operation at the Cincinnati Railway Iron Works, 

 and have attracted considerable local attention. 



The machine puddlers dispense with the hand labor of the 

 usual furnaces, performing the same duty by steam " power. 

 Those at present in operation are making puddled balls of from 

 650 to 700 pounds in weight; and others, of greater capacity, are 

 in process of construction. Samuel Danks, of that city, is the 

 inventor. 



SUSPENSION BRIDGE AT PITTSBURGH, PA. 



This bridge crosses the Alleghany about half a mile above its 

 junction with the Monongahela, both of which streams, when 

 united, form the Ohio. The town of Pittsburgh is situated on the 

 promontory made by the convergence of these two rivers, and 

 has, with its suburbs, a population of about 200,000. The dis- 

 tance between the abutments of the bridge is 1,037 feet 5 inches, 

 being divided into 2 main spans of 344 feet 6 inches each, one- 

 half span of 117 feet 5 inches, and a second half span of 171 feet. 

 4 wire cables carry the structure ; the 2 outer ones incline out- 

 wards from the towers, and. the 2 inner inwards, to give stability 

 to the bridge. The lighter cables which carry the footway are 

 each 4j| inches' diameter, that of the others being 7 inches. The 

 roadway is 20 feet wide, and the footways each 10 feet. The 

 cables are attached to bell-cranks at the towers, instead of by 

 saddles placed upon rollers, a by no means satisfactory 

 arrangement, the vibration of the bridge being increased per- 

 ceptibly by the lightest passing load. The towers are about 45 

 feet high. They are of cast iron, and of an ornate character, the 

 weight they support being entirely carried by the 4 inclined col- 

 umns, which are braced together by latticed castings. Scientific 

 American. 



A STEEP RAILWAY. 



A railway has been constructed in Pittsburgh, Pennsylvania, to 

 carry passengers to and from the top of what is known as Coal 

 Hill, which overlooks the city and the country around to a great 

 distance. 



The plane is located 250 feet west of the Monongahela suspen- 

 sion bridge. The roadway starting from Carson Street crosses the 



