284 



ENGINEERING. 



upon two iron girders. A timber scaffolding 

 was erected with four uprights, each composed 

 of six beams of heavy timber, placed three and 

 three, with a space between them to receive 

 the ends of the girders. The great mass was 

 lifted hv hydraulic jacks placed under the gird- 

 ers, until the height was as great as the dis- 

 tance between the trunnions and the larger 

 end of the obelisk. Each lift was secured by 

 heavy timber packing. When the proper 

 height was attained the fastenings were cut 

 away so that the stone could be swung upon 

 its trunnions, on which it was nicely balanced, 

 and when it was brought to a perpendicular it 

 was lowered into its seat. 



The new overhead railroads in the city of 

 New York are being built by two companies, 

 which have chosen two materially different 

 plans of construction. The Metropolitan Ele- 

 vated Railway (named at first, from the pro- 

 jector of the system, Dr. Rufus H. Gilbert, the 

 Gilbert Elevated Railway) was incorporated 

 by an act of the Legislature passed June 17, 

 1872. Work was commenced on the road in 



SECTION OF METROPOLITAN ROAD IN WEST BROADWAT. 



than half a minute. The engines weigh as 

 much as 15 tons, and are capable of a speed 

 of 40 miles or more an hour. The structure 

 differs somewhat in different portions of the 

 route. In West Broadway the girders are of 

 open lattice-work, the longitudinal girder rest- 

 ing on the transverse one inside of the pillars. 

 In West Third Street the transverse girders 

 are of plate, and the longitudinal trusses are 

 about 4 feet inside the columns. In South 

 Eifth Avenue the cross-girders span the whole 

 street, the posts being set in the curb. The 

 cross-girders are 40 feet wide and 3 feet 6 

 inches deep, and consist of plates. In Sixth 

 Avenue the longitudinal trusses are in a line 

 with the pillars, and the cross-girders are 

 latticed only in the center. The posts are 

 some distance outside of the curbstones. The 

 distance apart of the columns is about 13 feet 

 on the average in Sixth Avenue. The founda- 

 tions were made by excavating a hole about 6 

 feet deep and 6 feet square, and filling its bot- 

 tom with hydraulic cement 4 inches thick, on 

 which were laid two flat Milestones 5 or more 

 inches thick and 6 square 

 feet in area ; in these 

 stones four holes were 

 drilled and anchor-bolts 

 passed through, and then 

 brick masonry was built 

 on their top as high as 

 the level of the street, 4 

 feet square at the top 

 and all laid in hydraulic 

 mortar. The cast-iron 

 bed-plate, 3 feet 2 inches 

 square at the bottom and 

 15 inches high, weighing 

 1,200 pounds, was se- 

 cured to the foundations 

 by bolts 2 inches in diam- 

 eter. To the upper sur- 

 face of the iron bed-plate, 

 21 inches square, the bot- 

 tom of the wrought-iron 

 column was bolted by 8 

 bolts, each 1 inch in di- 

 ameter, and all covered in 

 with brick and cement. 

 The columns were com- 

 posed of two 12 -inch 

 wrought - iron channel - 

 bar 8 and two 12 -inch 

 channel-plates riveted to them. To the foot of 

 the columns were fastened four angle-iron bars. 

 The longitudinal girders are pin - connected 



\fnvM TOT \ 4 



o; but operations were embarrassed 



i! i" JU i2J2 n ^ ued by the courts ' 

 October, 1877, the final decisions were - 



favor of the road and all legal re- trusses, 6 feet 2 inches deep, and 5* feet from 

 >ved In this road the tracks are center to center of the pins vertically. The top 

 I over the middle of the streets by chord is made by two channel-bars, 8 inches 



dee P' united b ? * 12-inch plate. The pins are 

 3 inches in diameter, bolted at each end. The 

 yellow-pine cross-ties, 6 by 7 inches, 8* feet 

 long, and 24 inches apart between centers, 



alo ion> 1 V - r est on track-stringers of rolled beams, 8 by 4 



carTatatim Jt? g V UDl ad f Ur r five mches ' The rails weigh 56 Ibs. per yard. On 

 ne, as the stoppages are not longer each side of them are uard-rails to revent 



drw at the to P ^ 



* L ? wl ', lci \ the superstructure 



,o?l nVT^ h * alf a ^ ile apart ' 

 elmiu nf G i nt /r section8 of ^e 

 S atedlro The ? lat - 



