Proceedings of the Polytechnic Association. 965 



the Harlem river, but we make no use of it ; we should put it to 

 some useful purpose. 



Dr. J. B. Rich remarked that any one who has examined the situ- 

 ation of New York, M'ill see at once tliat a bridge elevated above tlie 

 water seems impossible. It would involve so much time that it 

 would hardly be worth while to go three-quarters of a mile in the 

 city to get something like a level. A man. will Bometimes present a 

 project one hundred years before the time ; it will be laughed at and 

 hardly any notice taken of it. So he viewed this plan of Mr. Dows. 

 There are many advantages to be derived from this plan ; and among 

 them is that of dee23ening our bay. This bay is well known to be 

 fast filling up, but the moment vre cut off the East river channel, 

 the water will be diverted in another direction and. clean our bay 

 very eifectually. It is the immense alluvial matter that comes down 

 the North river, over two hundred miles long, which strikes against 

 Governor's Island, that throws this matter into the East river, thus 

 choking up the channel there. All the arguments that the East river 

 keeps the channel open, are based upon a false foundation. If the 

 flow of the North river was more rapid, it would clear itself of its 

 many obstructions, which in a short time threaten to fill the harbor 

 entirely up. This plan of Mr. Dow's will quicken the current of 

 the North river considerably. Tliis channel is not filled up from 

 what comes in from the sea, but from the silt that comes down the 

 North river. 



Mr. Dudley Blanchard remarked that the Hudso-n or North river, 

 in the spring, is a very considerable river, but at other times it is not 

 an important river. The water flows up that river five hours, and 

 down seven hours. 



Mr. Dow stated that the tide of the East river runs up at the rate 

 of five miles an hour, and down at four miles. 



Mr. F. Shelbourne said that most every river that has its outlet 

 into the sea, has more than two channels, and when one is filled up 

 another is deepened. The channel at Sandy Hook has been a thou- 

 sand feet narrower, although Mr. Blunt denies this. 



Mr. C. E, Emery remarked that the tides appear to be a very for- 

 midable objection. Now what is the eft'ect of stopping it ? It must 

 raise the tide in other places. The flow will be found to be very 

 great up the North river; but this objection can be overcome by 

 liaving connection with the open sea, and thus shutting ofl" the water. 

 Vessels can be passed iji and out at all times. 



Adjourned for two weeks. 



