568 Transactions of the American Institxjte. 



The following is a brief description of the plan, and of the advan- 

 tages claimed: 



This is an under surfcuce railway, which contemplates the use of 

 the entire width of the streets and avenues under which it passes. 

 The excavation being made to a depth of some fifteen feet, extend- 

 ing to the line of areas, the sidewalks and roadway are replaced at 

 their present level on groined arches of solid masonry, springing 

 from heavy iron columns, which rest upon secure foundations, the 

 masonry of the arches being rendered water-tight by an impervious 

 asphaltum coating. Upon this is formed a roadbed of dry sand, 

 rammed and rounded to receive a pavement which need never be 

 disturbed until entirely worn out. The water-pipes gas-pipes, 

 sewers, telegraph wires, hydrants, lamp-posts, and all other matters 

 of public necessity connected with street thoroughfares, ai'e pro- 

 vided for in the design in a more complete, convenient, accessible 

 and systematic manner than at present. The whole length of the 

 arcade thus constructed is lighted and ventilated from the open 

 area adjoining the buildings, by means of which, also, free and 

 ready ingress and egress is afforded to the arcade at all points of 

 the route. The sidewalks of the arcade correspond with the side- 

 walks of the streets, and under the street are laid four lines of 

 railway, two for rapid transit, and two for way passengers. 



The lower or basement stories of the buildings along the route 

 are opened upon a broad, well lighted street, and can be used for 

 all the purposes to which the first floor is adapted, or any purpose 

 of trade or manufacture, making, therefore, just as many new 

 places of business as there are buildings along the line. At each 

 street crossing vaulted transepts are constructed, which, while 

 increasing the facilities of ventilation, add so much new space for 

 commercial storage, markets, or other purposes; and where the 

 route adjoins a public square, the whole of the line for that extent 

 can be used in like manner- The cars being always under a covered 

 way are never exposed to the weather, and can be constructed upon 

 principles of thorough ventilation. 



Whenever any portion of the coal vaults are taken, additional 

 room of equal value and capacity will be constructed at the 

 expense of the company, beneath the lower sidewalks. Should 

 the excavation be of a greater depth than the foundation of 

 the buildings, the same will be cai'efully secured by thorough 

 underpinning. 



The open ai'ea ways, with the addition of dead lights in the side- 



