THE HUDSON RIVER TUNNEL. . 99 
at the surface sufficiently to give the horses a foothold, without impairing the im- 
perviousness of the covering. It is suggested that it would be better to form the 
blocks with slightly truncated or rounded edges, so as to give the requisite foot- 
hold when the pavement is laid, rather than to secure the same end by the irreg- 
ular and ragged abrasion caused by use. As they are homogeneous in tough- 
ness and hardness, the blocks can be taken up, and their surfaces become un- 
even from unequal wear, and relaid in mortar, bottom side up, with all smooth- 
ness of a new pavement. It may be added that the process of refining and care- 
ful manipulation, is equally necessary whether the material be applied as a mon. 
olithic sheet, or as blocks, and any mixture that is suitable for the former is also 
suitable for the latter; also, that a form of sand is not a proper foundation in 
either case. — Roads, Streets and Pavements. 
THE HUDSON RIVER TUNNEL. 
The work of tunneling the Hudson River is pushing steadily on, and it is 
expected that in three years from now trains arriving in Jersey City will run di- 
rectly through to New York, and land their passengers in Broadway, somewhere 
fear the Metropolitan hotel, in six minutes’ time. The company says that more 
than too trains of cars could be passed through in twenty-four hours on the 
double track. 
Freight trains will use the tunnel exclusively at night, and market trains in 
the early morning. All will be drawn by engines made especially for the pur- 
pose. These will consume their own steam and smoke. A powerful engine will 
be always at work forcing air into the tunnel. The entire length of the tunnel 
will be 12,000 feet; that is, about one mile under water and three-quarters of a 
mile on each side. Thus far only the New Jersey end has been bored, but the 
work on this side will soon be begun and excavations will proceed from both 
banks until they meet. As many men will be kept constantly engaged day and 
night, as can be successfully employed at once, in making the hole and building 
the lining wall. The gangs will be changed every eight hours, thus doing three 
_ days labor every twenty-four hours. All the work will be done by electric light. 
The tunnel will be lined throughout with iron plates, and these in turn will be 
faced all over with the best hardened brick and hydraulic cement, three feet 
thick. The brick will be made from the refuse taken from the tunnel. This, it 
is said, will effect a saving of $2.25 on every thousand used. As there will be 
2,013 brick in each running foot of wall, it will be seen that the saving is consid- 
erable. The interior will be painted white and lighted with gas. The entrance 
in Jersey City will be from Jersey avenue in Fifteenth street. The tunnel will be 
a single one, twenty-six feet wide and twenty-four feet high in the clear down to 
within a few feet of the river on both sides, and a double one all of the way un- 
_ der the water where the two tunnels will run side by side, each eighteen feet 
high and sixteen feet wide in the clear. It is to extend from Jersey avenue to 
IV—7 
