The great necessity of New York is some sure means of rapid transit between the upper and lower parts of the island. The average New Yorker spends about an hour or an hour and a half each day in going to and from his business, and an immense amount of valuable time is thus lost, which loss is often increased by delays. For the past few years the citizens of the metropolis have been seeking to procure the construction of a road from the Battery to Harlem to be operated by steam, and it seems probable now that a few years more will witness the completion of such a road. Public opinion is divided between two plans, and it is probable that both will be tried, and that the city will soon contain a steam railway elevated above the street and a similar road under the ground. The elevated railway has already been tried to a limited extent, but is not regarded with much favor by the citizens. This line extends along Greenwich street and Ninth avenue, from the Battery to Thirtieth street. The track of this road is laid on iron posts, at an elevation of about sixteen feet above the street. The cars are so constructed that it would be impossible for one of them to fall from the track. Dummy engines furnish the motive power. The running time from the present southern terminus at Courtlandt street to Thirtieth street, a distance of about three miles, is fifteen minutes. The road is pronounced perfectly safe by competent engineers, but the structure appears so light to the unscientific public that nine out of ten view it with distrust, and it is doubtful whether it will ever meet with the success the company hope for. The only other elevated road at present contemplated, and for which a liberal charter has been obtained, is known as the _Viaduct Road_. It is proposed to build this on a series of arches of solid masonry, the streets to be spanned by light bridges. The line of the road is to be in the centre of the blocks along its route. The estimated cost of the road, including the sum to be paid for the right of way, is about $80,000,000; and it seems certain that this immense cost will necessitate radical changes in the original plan. [Picture: TUNNEL UNDER BROADWAY.]