PnOCEEBTKGS OF THE POLYTECHNIC ASSOCIATION. 979 



tlie tendency will bo to prolong the suspension of silt, and not only 

 increase the scour at Sandy Hook out rednce materially the daily 

 deposit there and in the harbor. This covers not only tlie very 

 important item of improved river connnerce, which commerce is of 

 vastly o-reater consequence than the coastinii^ trade of the sound, since 

 it pertains to Xcw York, and the great west and Canada, but it 

 directly alleviates the groat annual expense of slip and basin dredfino- 

 along the commercial front of the rivers, vvdiere now an annual 

 deposit of silt of twelve to eighteen inches in depth occurs, atlributa- 

 ble to some extent to city seAvage, steamer ashes, and other local 

 causes, but not so prominently, for sewage flow, surcharged Mdtli 

 Croton water and running freely through miles of culverts, does not 

 change its nature when it strikes the tide, as caif be shown by abun- 

 dant testimony,' if such details were not excluded from our present 

 argument. 



With these ship channel and river benefits come the direct benefits 

 to the East river itself. It is now an almost nnnavigable and non- 

 commercial gorge, swept as it is, four times a day, with swift cur- 

 rents; dangerous even to vessels at the wharves, they can hardly 

 enter and leave Avith the experienced hel]) of our large fleet of steam 

 tugs created by these dangers ; unsafe for sailing vessels, for anchor- 

 age, and for ferries ; obstructed in winter seasons often, with vast 

 fields of ice, practically severing tlie tv.'o great cities aij-d giving rise 

 to continual complaints ; rcstnetcd also by rigid laws in its bulkhead 

 and pier extcnsion>^, so that a great comtnercial city, which hopes 

 within fifty years to rival Liv'.n'pool, cannot now berth her waiting- 

 ships, and drives her cornmerco to an opposite shore. 



Under the present plan for the improvement of Hellgate the 

 government is expected to spend $T,000,000 to secure twenty-six feet 

 waterway. A clear waterway for tlie maiii channels is of course val- 

 uable, l")ui this expenditure will not practically imjirove the naviga- 

 tion of Hellgate, as the best authorities have admitted, simply 

 because it will not reduce the excessive velocities of the tidal ^airrents 

 of eight. and a half to eleven knots an 'hour, which now make the 

 crooked channels a terror to vessels of all classes, and an impossibility 

 to sailing vessels of ocean draft and bulk. These and other civic 

 and commercial obstacles, will 1)0 at once relieved by relieving their 

 actuating cause and giving tlie East river, from tiie Battery to Throg's 

 jSTeck. no otlier currents than those of ordinary tidal rise and fall. 



Althougli this project involves no immediate change in the Harlem 



