Chapter XII · STEAM NAVIGATION—THE ‘GREAT EASTERN’ STEAM-SHIP. THE LAUNCH. A.D. 1857—1858. ÆTATIS 52. (continued 2)

The results obtained by the observations made on the motion of the ship having shown that its behaviour when in motion accorded with that of the experimental cradle, there is every reason to believe that if the ship had ever attained a velocity of 1½ to 2 feet per second, which might have happened had the river tackle acted well, the friction would, as in the experimental cradle, have become less than the action of gravity down the slope, and the brakes would have had to be employed to check the motion.

NOTE B (p. 384).

Letter from Mr. Brunel to W. Froude, Esq.

February 2, 1858.

My dear Froude,—It is no news to you to tell you that we have floated, but still you will perhaps feel sympathetically some pleasure in hearing of it from me, as I do in writing to you upon it.

We have in fact gone on well and without mishap since we have resumed operations with plenty of power; we have not gone very quickly because our jumps have been small, or we have gone by a continuous motion—we have had a great deal of this, and all the last 30 or 40 feet I think, or more, has been so, the power being with gravity about a quarter of the weight, sometimes less—occasionally, when the water was high, considerably less—buoyancy being of course taken duly into the calculation. Once, when still weighing fully 3,500 tons, and with 1,200 tons of water in her, making 4,700, less some buoyancy of the cradle, she moved so easily that they came running to me from the other cradle, to say that she was moving of herself, and asking what to do.

She certainly had not much more pressure on than we had assumed to be necessary to overcome all the friction of thrust timbers, &c., certainly could not have had above 300 tons of real push to move

2,000 tons, 2, 000— 2,000 12 (gravity) = 1,833 tons.

I think that when the load became much lighter on the rails, that the mud and even the sand of the Thames form a lubricator and rollers which offered less resistance than the dry rail, or the rail with pressure enough to displace the mud or imbed the sand.

Having at last pushed the cradles beyond the rail, and found her stand well, and moved a few feet more and still stand upright, I waited for a tide, and arranged a good communication with Liverpool and Plymouth to telegraph up wind and weather, morning and night, so as to help in foreseeing a tide.

On Friday morning, at 3 A.M., the tide began to improve, but the wind was still in the wrong quarter for a good tide, and as I think I have told you the tides of this month, and of the whole year of ‘58, are very poor. Besides this, it blew a gale. I therefore began pumping out the water, but stopped at 1,200 tons, and at 10 A.M., seeing no improvement in the weather, I filled in by the fire-engine about 1,300 or 1,400 more, and gave up the attempt, and very fortunately, as the tide did not rise high enough, and the wind right on her broadside increased.

On Saturday night things grew worse, and the wind at Liverpool and Falmouth finished in the evening still SSW. About midnight the wind lulled, the rain came down in torrents; the wind gradually stole round to the northward, and the tide came rolling up uncomfortably quick. I admitted water as soon as it would run in, and only just prevented her floating; when, if she had, we should have been in a mess, as our wedge-pieces were not yet unbolted from the bottom, nor could we in the night have managed the floating, even if all had been ready, which nothing was. Under these circumstances, the wedge-piece being bolted was perhaps our security, as she all but floated; the stern rose 3 inches though we had 3,000 tons of water in her, the tide rose so high; we began pumping immediately on the turn of tide, and by half-past 6 A.M. the wind was gentle from the NNE., and telegraphs came to announce the same in Liverpool, &c. I therefore determined upon floating.

We pumped away, and at 10 A.M. cleared everything away, and began our preparations. I had fixed 12 o’clock to begin forcing her further down, thinking half-past 12 would have been as early as she would have moved easily, but the tide came rushing up an hour and a half before its time; and, although I hurried the men to their posts, we were rather caught napping. The instant we began pressing, she moved easily, and by a quarter past 1 we had pushed her centre past the ways, and she began lifting with the tide.

I had a centre station with a chalk board, giving me the curve of the tide, and two good levels reading off her stem and stern water marks. Our calculations had proved very correct. In the skew position I had pushed her to, she began lifting at the stern first, as she ought to have done, and her bows soon followed the example. We stopped pushing the cradles, made them fast, and began hauling out the ship—she moved very slowly of course.

When she began to move out, our first difficulty occurred by a little mismanagement, or over confidence, on board; our stern chain was let go, and she forged ahead against the tide by the elastic strain of the bow chain, and I think also by the tug-boats pulling too much, which ought not to have been done, and in going ahead her port paddles caught hold of some cradle timber rising, with long 2½ inch bolts holding them to the bottom of cradle. No tug power would have had any effect upon them. But we had two hours before us, with a promise of an unusual tide; I hurried on board, and we succeeded in about twenty minutes in getting a little astern a little out, and getting clear.

We had some mishaps after this, such as fouling one of our barges, getting it jammed under the paddlewheels, and the barge fast by the chain tackle dropt overboard. However, we scuttled and sunk the barge, and got safely across. We had an extraordinary tide, and several assistances from nature to counteract any of our own bungling, and got safely across, and she is now moored in her right place.

Yours faithfully, I. K. BRUNEL.

William Froude, Esq.