960 Transactions of the American Institute, 



they say : " Ice, which go frequently obatructs the ferries, gives little 

 ©r no trouble to the basin. That which forms inside is thin, and 

 kept broken and fragmentary by the constant movement of vessels. 

 When the ice is coming in on a flood tide, the basin entrance is 

 temporarily barred by a float, wliich wards off the ice, and induces it 

 to pursue further on its search for a nook or bay in which to entrench 

 i^eelf." Their depth of water is only twenty-five feet ; and when we 

 consider that in the proposed basins the water will be from forty to 

 sixty feet deep, and that the whole body of water, from the surface 

 to the bottom, mnst be chilled to the freezing point before ice can 

 form on the surface, and that, in the coldest weather, we can prevent 

 that chill, by exchanging the inside water of the docks for the 

 warmer water just brought in from the ocean. It is easy to see that 

 we can always be free from ice, and not even troubled, as now, by 

 the North river ice, which the dykes would keep away entirely. 



On the third objection, concerning the silt or mud and sewerage, 

 it is too early at present to say precisely what may be done in this 

 direction. It is pretty certain, however, that this matter cannot be 

 in a much worse condition than it is now in. The slips of New 

 York and Brooklyn are filling up at the rate of one and a half and 

 two feet per annum, and are only kept free by the dredging machines. 

 That a very lai'ge portion of this silt comes down from the North 

 river is proved by the fact that at the Cunard wharf in Jersey city, 

 ten feet of mud are dredged out annually. The proposed dykes 

 would shut this off, and a constant high water in the basins would 

 prevent any of the present sewerage stenches of the low tides ; and 

 the sewerage stuflf could as well be dredged out then as it now has to 

 be, and in many cases at private expense. It is believed, however, 

 that this manure may be retained in tanks, and pumped out and 

 carried off at an expense which the agriculturists will gladly pay for 

 its use ; but of one thing we may be sure, that the owners of the 

 docks, in self protection, will not allow the sewerage in any way to 

 injure their property, so the public have nothing to fear from that 

 source. Nor is there the least danger that they will over allow the 

 basins otherwise to fill up so that they cannot be used. 



We come now to the fourth and most important objection : whether 

 ^these dykes and docks would not cause such efl'ects on the running 

 "waters as might injure rather than improve our main channel to the 

 ocean, as has been noticed in the Boston harbor. 



It'is a fundamental rule laid down on the experience of European 



