Page:The American Cyclopædia (1879) Volume III.djvu/244

 238 BREAKWATER constructed along the line of the breakwater on which the trucks were propelled, and from which their contents were dumped into the water. The quantity of stone deposited per day varied from 2,000 to 3,000 tons, the total quantity used in the work being about 6,000,000 tons. It was quarried and landed mostly by convict labor, from 600 to 1,000 prisoners having been employed. About 100 men were engaged in the actual work of construction. The cost of this extensive work has been only about 1,013,000, for which the British nation possesses one of the most magnificent harbors in the world. In 1828 a commission consist- ing of Commodore Rogers of the navy, Brig. Gen. Barnard of the engineer corps, and Wil- liam Strickland, architect and engineer, was appointed by the United States congress to as- certain the most eligible site and to prepare plans and estimates for a harbor near the mouth of Delaware bay. In their report, made Feb. 2, 1829, they selected Cape Henlo- pen as the site of a breakwater. They said : " The objects to be gained by an artificial har- bor in this roadstead are to shelter vessels from the action of the waves caused by winds blowing from east to northwest round by the north, and also to protect them from injuries arising from floating ice descending from the northwest." They proposed two works, a breakwater proper, to secure the first object, and an ice-breaker, as an auxiliary to the breakwater, but chiefly to protect vessels against the ice. The breakwater was design- ed with a length of 1,200 yards, and on a course 5T. N. W. drawn from a pitch of the cape. The ice-breaker was designed with a length of 500 yards, on a course W. by S. J S., and so placed that the line of the breakwater would meet its S. W. extremity if extended, leav- ing an opening between the breakwater and cape of 500 yards, and between the breakwater and ice-breaker an opening of 350 yards, with a depth of water of 24 ft. The area protected 'against all the most dangerous winds, with a depth of 3 to 6 fathoms, is estimated at 360 acres. FIG. 4. Section of Delaware Breakwater. The work was commenced in 1829, under direc- tion of Mr. Strickland, and in 1834 it was so far advanced that vessels found protection behind it. Blocks of rubble from the nearest quarries were thrown in to form their own slopes for a foundation. The outer covering to within 6 ft. of low-water mark was of blocks from 2 to 3 tons weight ; from this to low-water mark they were of 3 tons ; thence to high-water mark, 3 to 4 tons ; and above this, 4 to 5 tons, to a height of 4 ft. 3 in. above highest water. The ordinary rise of tide is nearly 5 ft., equi- noctial tides 7 ft., and extreme tides 10 ft. As the breakwater was built, its exterior slope for the first 16 ft. from bottom was at an angle of 45, thence to summit 28, or 3 to 1. The inner slope was 45. The surfaces of both slopes to the level of low water were paved with rough blocks set at right angles to the slope, and well wedged together, thus present- ing as little surface as practicable to the action of the waves. The stone used in this work was obtained from a variety of sources, some trap rock from the Palisades on the Hudson river, greenstone from the northern part of Delaware, and gneiss from different quarries in Delaware. These rocks, though averaging a weight of 175 Ibs. to the cubic foot, and employed of the dimensions named, were insufficient to with- stand the action of the sea in the course of the construction of the moles. During the winter season, those upon the surface of the work were more or less displaced, and a large piece of 7 tons weight was moved in one storm 18 ft. to the inner slope of -the ice-breaker, down which it was lost. At the same time about 200 tons of other heavy stone, that had been thoroughly wedged and compacted together, was torn up and swept over to the inner side. In 1839, according to the report of Major Bache in 1843, the breakwater was in course of construction for 862 yards, and the ice- breaker for 467 yards. Gen. (then Major) J. G. Barnard, in a report of the works made by him in 1853, says: "The last stone was depos- ited on the work under former appropriations in the year 1839 ; and since that date a work costing already nearly two millions of dollars, a work in every sense national, has remained in its half finished condition." As long ago as 1843 various plans were proposed for comple- ting the work and rendering the harbor more commodious. Major Bache, in the report he- fore referred to, says : " In order to remedy the defects of the harbor which are caused by the rolling of the sea entering between the works, three modes have been suggested: 1, to cover the gap by extending the ice-breaker; 2, to close the gap by extending the breakwater proper ; and 3, to cover the gap by a detached work." He estimates the cost of each of the plans to be as follows : " 1, for closing the gap by extending the breakwater, $551,635; 2, for covering the gap by extending the ice-breaker, $815,341 ; 3, for covering the gap by a de- tached work, $959,664. To these estimates must be added severally the sum of $108,921 for raising the existing works to their proper level, and for filling holes in the bottom at their ends." The report of Lieut. Col. J. D. Kurtz, of the engineers, for the year ending June 30, 1870, contains the following: "From July 1, 1869, to the completion of these works in conformity with the present design, Nov. 4, 1869, the work was carried on in furnishing stone by contract as heretofore, the United States performing the labor of placing the large stone in position by days' work. During the fiscal year 10,698 tons of large stone for the