28 ANNUAL OF SCIENTIFIC DISCOVERY. 



repairing a vessel without docking. The United States' ship of the line, Del- 

 aware, immediately after launching, lost a portion of her copper. There being 

 no government dry-dock at that tune, the ship was allowed to remain in that 

 condition until orders came to fit her for sea, when, in order to make her outfit 

 as complete below as above water, Mr. Broadie, the foreman of the yard, pro- 

 posed and obtained leave to make a box, with open top and side, to cover the 

 part to be repaired, one side to fit the side of the ship. The locality of the spot 

 from which the copper was removed being known, there was little difficulty in 

 preparing timbers of the shape of the side of the vessel, upon which a box, 

 or diving-bell, was projected, of sufficient size and strength to sustain the 

 pressure of the water from without when the water from within was removed. 

 "When finished, the edges, coming against the side of the ship, and forming 

 the margin of the open side, were padded with canvas, so as to be brought 

 close to prevent the passage of the water, and the whole fabric being provided 

 with ring-bolts, for securing the box to its place, by means of ropes passed 

 under the keel and up the opposite side, in like manner it was secured firmly 

 fore and aft; and when thus made fast, the water was pumped out, and work- 

 men went down to the place, when the copper and worm-eaten plank were 

 removed, a new plank inserted, fastened, caulked, and re-coppered. All this 

 while the ship was afloat, and the defective part from 15 to 18 feet below the 

 surface of the water. The ship went to sea and performed the usual cruise 

 of three years, more or less, and Mr. Broadie was awarded $500 by Congress, 

 for his mechanical skill. 



IMPROVEMENTS IN SHIPS AND STEAMERS. 



Cunard Steamship Persia. During the past season, a new iron steamer, 

 the Persia, has been launched by the Cunard Steamship Company, at Glasgow, 

 Scotland. This vessel, at present, is the largest steamer afloat, far exceeding 

 in length, strength, tonnage, and steam power, the Great Britain or the 

 Himalaya, and exceeding also by no less than 1200 tons the internal capacity 

 of the largest of the present splendid Cunard liners. Her chief proportions 

 may be summed up as follows : 



Length from figure-head to taffrail 390 feet. 



Length in the water 360 " 



Breadth of the hull 45 " 



Breadth over all 71 " 



Depth 32 " 



Stupendous as the Persia is, the lines of beauty have been so well worked 

 out in the preparation of her model that her appearance is singularly grace- 

 ful and lightsome. Tet this mighty fabric, so beautiful as a whole, is made 

 up of innumerable pieces of ponderous metal, welded, jointed, and riveted 

 into each other with exceeding deftness. The keel consists of several bars of 

 iron about 35 feet in length each, joined together by long scarfs, and as a 

 whole 13 niches deep by 4 inches thick. The framing is constructed in a 

 manner at once peculiar, and securing the greatest possible amount of strength. 



