The distance being about forty miles, over a country extremely broken and uneven, and following a direction, for a portion of this distance, parallel with the Hudson River, encountering the streams which

empty into it and form deep valleys in their courses. It will

be interesting to notice the different plans which were suggested for forming a channel-way to conduct the water. The following modes were presented : --a plain channel formed of earth, like the ordinary construction of a canal feeder --an open channel, protected against the action of the :

current by masonry -- an arched: or comculvert conduit, posed essentially of masonry ; and iron pipes. In deciding which of these modes should be adopted, it was necessary to make a comparison among them as to their efficiency for conducting the water in purity, and in the quantity required, their permanency as structures, and their cost.

The disadvantages attendant upon an open canal were, that by filtration through the banks there would be a heavy loss of water ; --the difficulty of preserving the water from receiving the wash of the country, and preventing injurious matter from being thrown into it and rendering it impure, and the impurities which might be contracted by passing through different earths. Evaporation would also occasion a serious loss of water. The banks would be liable to failure in seasons of long-continued rains, and the city depending

upon this for a supply, would be cut off, except there should be sufficient in the reservoirs to furnish a supply during the period of repairs. The canal could never be subjected to a thorough repair, because of the necessity of keeping it in a condition for furnishing water constantly during the whole year, so that all repairs would be done under great disadvantages, and the channel would be yearly growing worse until its failure might become a public calamity.