Although it was found that the bracing-chains could not withstand the shaking and tremulous motion of the Beacon, yet they were again set up and tightened, with the exception of the two that had lifted their bats, with a mass of the rock; which were knocked off altogether. It is here worthy of remark, that the bolts of the bracing screws had always a tendency to unlock, and one of the nuts, as before noticed, had even unscrewed no less than three inches. To prevent this in future, a piece of small wire was turned round the threads of each screw, which had a tendency to preserve them; but still the chains stretched, became loose, and broke their eye-bolts, or lifted part of the rock with the strain. The bracing-chains may, however, be conceived to have had some effect in checking the force of the waves, as was observable in the operation of the sea upon the extensive beds of marine plants. It often happened, when heavy seas were rolling along the Bell Rock, which at a distance threatened to overrun the whole, that, upon reaching these beds of fuci, with which the flat and level parts of the rock were thickly coated, the velocity and force of the waves were immediately checked, and in a great measure destroyed.
[Sidenote: Professor Playfair’s observations about the unlocking of screws.]
The unlocking of screws, where _washers_ had been introduced as a security, was rather unexpected, and the writer took an opportunity of conversing with his much respected friend Professor PLAYFAIR of Edinburgh, regarding this circumstance. The Professor observed, that he had experienced some inconveniency of this kind from the unlocking of almost all the screws of a telescope, which had been sent to him from London by the mail-coach. Indeed from the spiral form of the screw, which is, in fact, an inclined plane, Mr Playfair readily accounted for such an occurrence; and when reflected upon, it seems to be an effect rather to be looked for, and is a reason why rivetting the point of a bolt, in preference to screwing it, should generally be resorted to, where much friction or motion is to be apprehended.
At this visit to the Bell Rock, the writer went also on board of the Floating-light, where every thing was found in good order. On some occasions Mr Sinclair, the commander, stated, that the vessel had rolled excessively hard; that she had shipped two or three very heavy seas over the waste-boards, and that he had found it occasionally necessary to veer out 80 fathoms of cable. He also stated, that the floating-light had been _run foul of_ by a large smack-rigged vessel, with all her canvas set, though the lights were burning perfectly clear. This vessel had struck upon the larboard quarter, damaged the taff-rail, and started three of the floating-lights’ trenails. That they immediately hailed the vessel, but she sheered-off, and her crew made no reply. The smack was beating to the northward, and was much lumbered on the quarter-deck with packages of earthen-ware, which were distinctly seen upon her deck from the brilliancy of the lights.