368 Royal Society. 



superintendence, was, by the great, persevering and meritorious ex- 

 ertions of his officers and crew, most successfully accomplished. 



The narrative commences with the statement of the consternation 

 produced at Rio de Janeiro on the receipt of the intelligence of the 

 loss of the Thetis, with a freight of about 810,000 dollars, on the 

 south-west side of the island of Cape Frio, and of the determination 

 of the author, on finding that no one seemed disposed to take any 

 step towards the recovery of the property thus lost, to make the at- 

 tempt himself, if he could obtain from the Commander-in-chief at that 

 6tation, Rear-Admiral Thomas Baker, C.B., orders to that effect. He 

 accordingly exerted himself to obtain every possible information rela- 

 tive to the nature of the coast, depth of water, and other circumstances, 

 which might enable him to judge of the practicability of the under- 

 taking, and of the means necessary for its successful accomplishment; 

 and became convinced that the difficulties and obstacles to be en- 

 countered, although numerous and formidable, might be overcome by 

 the employment of the means which suggested themselves to him as 

 practicable on this occasion, if sufficient assistance were afforded him 

 in putting them into execution. He accordingly had models of the 

 proposed machinery made, and submitted them, together with his 

 plans, to the Commander-in-chief, by whom they were approved. He 

 experienced great difficulties in procuring a suitable diving-bell, for it 

 was impossible to obtain any instrument of the kind at Rio de Janeiro, 

 or even any facilities for the construction of one by casting. It at 

 length occurred to him that a ship's iron water-tank might be con- 

 verted to this use ; and being supplied with one from the Warspite, he 

 was enabled to render it available for that purpose. The next diffi- 

 culty was to procure an air-pump, which, after much delay, owing to 

 the tardiness of the native workmen in that country, was at length 

 constructed. The want of air-hoses, however, was a still more for- 

 midable obstacle to the success of the plan ; but the ingenious con- 

 trivances of the author for rendering the common pump hoses air- 

 tight, supplied this deficiency ; and on a trial which he made with the 

 whole apparatus on the 22nd of January, 1831, it was found to an- 

 swer completely. The next day he received his orders from the Com- 

 mander-in-chief, and, sailing on the following day, arrived at the har- 

 bour of Cape Frio on the 30th, and immediately proceeded to inspect 

 the coast, and ascertain the situation of the wreck, not a vestige of 

 which was visible. An account is then given of the local circumstances 

 of the Thetis Cove, or inlet, surrounded by almost perpendicular cliffs 

 from 108 to 194 feet in height, with a depth of water varying from 

 3^ to 24 fathoms, and the bottom being strewed with huge perpen- 

 dicular rocks, occasioning these inequalities. These surveys showed 

 that the. execution of the plan originally conceived by the author was 

 opposed by so many unforeseen difficulties, that he was obliged to re- 

 linquish some parts of it, and resort to fresh expedients for surmount- 

 ing them. The idea of constructing a derrick then occurred to him ; 

 but the materials were wanting, for no trees existed in the island ex- 

 cept those in the forests in the interior, which were inaccessible from 



