Soon afterwards Mr. Brunel was informed that the ‘Acheron’ would be prepared for the screw. He thereupon represented to their Lordships that the ‘Acheron’ could not, from her full after-body and other defects, be converted into such a ship as the Board had originally determined to construct for trying the screw; and, indeed, her unfitness was admitted by the authorities themselves. To a letter on this subject, in which he stated that the attempt to apply the screw propeller to the ‘Acheron’ would not answer any of the objects which their Lordships had in view, Mr. Brunel received no reply, and for the next four months was kept quite in the dark as to what was going on. At length he made enquiries as to the cause of a treatment which, he said, he had never before experienced from any public body. These enquiries proving fruitless, he at last wrote to the Admiralty, declining further interference, as it had appeared on investigation that the condition on which he had accepted his position from Lord Minto--namely, that he should have the entire superintendence of the experiments--had not been observed. On the receipt of his resignation, Mr. Brunel was summoned to the Admiralty. He thus described his interview in a letter to a friend:-- Not a word was said about my complaint of the past, but they said they wished me to continue the experiments, and that my screw was to be tried first. I said that was not at all what would suit me; that I would, if they wished it, conduct an experiment as originally proposed; that I had no screw, that I was no competitor, but an arbitrator in whom the Admiralty had perfect confidence; that I was this or nothing. Then commenced a tedious fencing.... However, it ended in all parties being written to, and told that they were to follow my directions, and that I was to proceed to give such instructions as should enable a full experiment to be made of all screws generally. I then requested that this time I might have my instructions in writing. In a few days Mr. Brunel received an official intimation that the ‘Rattler’ was to be adapted for the screw, under his directions. The ‘Rattler’ was a vessel of 888 tons burden, 176 feet 6 inches between the perpendiculars, and 32 feet 8½ inches beam.[136] She had been commenced for a paddle-wheel steamer shortly before, and was of nearly the same tonnage and midship section as the ‘Polyphemus,’ but she had not the fine lines aft which were so important for the use of the screw. She was not launched until April 13, 1843, just two years after Mr. Brunel’s first interview with Lord Minto; and she was then delivered to Messrs. Maudslay in the roughest possible state.