108 MEMOIR ON BOSTON HARBOR. 



founded should be fully and distinctly communicated, in order that they may undergo 

 strict examination and complete discussion. This part of the subject is of necessity, 

 therefore, indefinitely postponed. I cannot, however, take leave of it for the present, 

 without expressing the opinion that the plan of construction on South Boston Flats con- 

 tained in the partial report of the present Commissioners, dated March 22, 1851, is not 

 suited to accomplish the declared objects, — which are, "to improve the channel and at 

 the same time to enlarge, in the best practicable way, the wharf and dock accommoda- 

 tions of the city, to meet the new demands of its growing commerce " (p. 14), — but that 

 it will injure the main ship-channel in one of its weak places, by causing an increase of 

 deposit on the side of the Bird Island Flats, by making it more crooked in this part, 

 and by lessening its capacity ; at the same time it affords no additional accommodations 

 to commerce of permanent value and utility, and threatens to hasten the destruction 

 of Fore Point Channel. 



One of the purposes of this memoir has been, to impart the evidences of deteriora- 

 tion in the upper basin. Having these evidences, it was thought expedient, especially 

 when my previous relation to the subject is considered, to make them known. But to 

 prevent any unnecessary apprehension of the immediately fatal consequences of this de- 

 terioration, and to do justice to our admirable harbor, unsurpassed in its convenience, 

 security, and ample dimensions, as it is rarely equalled in its beauty, it may be well to 

 compare it with a few of the principal maritime ports of the world. 



At New York (to begin at home) there are twenty and twenty-one feet of water on 

 the bar, and the mean rise and fall of tides is five feet ; the depth at the entrance of the 

 inner harbor of Boston is eighteen feet, and the mean rise and fall of the tides ten feet ; 

 making the average depth in the two places about the same. Boston, however, enjoys 

 this double superiority, — that, while at New York the bar is at the outer entrance, and 

 ships must keep the sea until they are able to pass it, at Boston the bar is at the entrance 

 of the inner basin, vessels are landlocked when they reach it, and, if compelled to wait 

 for the tide, can lie in safety ; and Boston, moreover, has several excellent roadsteads, 

 in which New York is comparatively deficient. 



At the entrance of the estuary of the Mersey, there are only eleven feet of water at 

 low spring tides ; but the rise of tide varies from twenty-one to thirty-one feet. The con- 

 struction of a new harbor of refuge, at great cost, in this vicinity, is one of the splendid 

 enterprises in which the British are now engaged. The harbors of Dublin are artificial ; 

 a bar prevents the entrance of large vessels into the river, and the navigation of the bay is 

 very dangerous in stormy weather. The channel of the river Clyde above Greenwich is 

 only three hundred feet wide, and at Glasgow there is now, after all the remarkably sue- 



