Note 176 — Chapter XIII · STEAM NAVIGATION—THE ‘GREAT EASTERN’ STEAM-SHIP. COMPLETION AND SUBSEQUENT HISTORY. A.D. 1858-1859: ÆTATIS 52-54. A.D. 1859-1870.
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Before the ship was finished, Mr. Brunel had her stability and rolling carefully investigated. Calculations were made to ascertain the position of her centre of gravity and the other necessary elements for determining her stability and period of rolling.
He also had a model made, with arrangements for altering the levels of weights placed inside. By this means the results of the calculations were verified. It was determined that the ship would make a single roll from one side to the other in about six seconds. While she was in the Thames a steamer struck the hulk alongside and gave the great ship a slight impulse. Mr. Brunel, who was on board, took advantage of the opportunity to observe the period of the roll she made, and was pleased at finding it agree with the calculated period. It is to the investigations initiated at that time by Mr. Brunel that are due the great steps since made in the knowledge of the laws which govern the rolling of ships. Had Mr. Brunel lived he would no doubt have taken the same pains to record the rolling of the ‘Great Eastern’ as he had in the case of the ‘Great Western’ when, in 1839, he sent an assistant to America and back, who took observations of the rolling and pitching of that vessel in several voyages. These observations were made by a simple angle-measuring instrument, adjusted by the visible level line of the horizon, and not by the fallacious method of noting down the swings of a pendulum.
The ‘Great Eastern’ remains almost perfectly steady in ordinary rough seas. When the seas become very long, so that their period is nearly the same as that of the ship, she rolls; though the number of degrees on either side of the perpendicular is not large. By stowing the weights of cargo high in the ship, the tendency to roll has been much diminished, and when engaged in cable laying, with the enormous weights in the cable tanks all placed above the lower deck, she is remarkably steady.