94 ANNUAL OF SCIENTIFIC DISCOVERY. 



tively great control which may be exercised over the operations of 

 those destructive agents. 



REPAIRING OF THE GREAT EASTERN. 



In a voyage from Liverpool to New York, in October, 1862, the 

 steamship Great Eastern struck upon a rock off the coast of Long 

 Island, damaging and crushing in the iron plates on the port side for 

 a distance of some sixteen feet. Owing to the huge dimensions of 

 the vessel, and her inability to enter any existing dry-dock, the 

 problem of repairing a damage of such an extent, situated some 

 twenty-five feet below the water-line, was one not only of great en- 

 gineering interest, but also one of great difficulty. Before detailing 

 the manner in which^this was accomplished, it is desirable to^recall 

 briefly the peculiarities of the vessel's construction. 



The hull is formed of two distinct vessels as it were, one inside of 

 the other. These skins are stayed to each other by a number of 

 webs or partitions, that divide the vessel transversely into thirty-four 

 spaces ; they run the whole length from stem to stern. The webs are 

 further crossed at right angles by thirteen separations which consti- 

 tute a system of water-tight cells, each of which is entirely inde- 

 pendent of the other, access being had to each cell through man- 

 holes, provided with plates, that open into them. It must be borne 

 in mind also that there are, inside of the ship proper, two upright 

 iron bulkheads that divide the hull into three long rooms. Now the 

 man-hole plates previously mentioned communicate with each other 

 from the upper series of cells in the ship's broadside down to the foot 

 of the bulkhead before mentioned. There they stop. The arrange- 

 ment on the other side is of course similar. The inner room has two 

 man-hole plates on the inner skin, which allow access to the cellular 

 divisions situated beneath it. These are connected through one 

 another by the same plan as the others. In brief, the Great Eastern 

 is a ship built up of a series of rectangular pipes, independent of each 

 other, yet capable of being connected together. 



Let us now return to the subject of the disaster. The fracture was 

 entirely through the outer plating of the ship, and extended over 

 three of the longitudinal cells. To close up the sides by any other 

 means than with new plates was simply impossible, and these had to 

 be put on while the vessel was in the water at her anchorage. The 

 stubborn broken plates with their ragged edges afforded not the 

 slightest hint that could be seized upon to accomplish the work short 

 of much time and labor. Preliminary consultations resulted in decid- 

 ing the authorities to adopt the expedient of a dam which should 

 inclose the point of rupture on all sides, and which, by means of 

 pumps, could be freed from water and rendered habitable while the 

 operations were in progress. 



A coffer-dam was built of heavy oak timber, semi-circular in form, 

 and planked outside four inches thick. It was ascertained that thirty- 

 two tons of iron would be required to sink the scow, and it was forth- 

 with partially submerged, while two chutes, hereafter mentioned, were 

 affixed. Previously, however, two heavy chains had been attached to 

 each side of it, in such a manner that the cable, fastened on to the 



