Aristotle, 300 years B.C., makes some obscure references to a machine of this kind, but what it was or how employed is not known. The first reliable account we have of such a machine is given by Taisnier, who describes a "cacobus aquaticus" (marine kettle) which was exhibited by two Greeks before the Emperor Charles V., at Toledo, in 1538; but it seems to have been of no practical use, as it had no apparatus for supplying the divers with fresh air. A similar sort of bell, but constructed on better principles, had been made use of on the coast of Mull, between the years 1650 and 1660 to operate upon some sunken vessels of the Spanish Armada, but without much success. It was this which directed the attention of Phipps to the diving-bell, who perceived that by various modifications and improvements of the apparatus it might be made a most valuable instrument for submarine operations, and after a long and patient study, and numberless experiments, he succeeded in constructing a bell very much the same as that now used, and capable of being worked much more efficiently and with greater safety than any previously employed. In consequence of his having thus, by his skill and scientific modifications, produced a really working machine, he is generally styled "the inventor of the diving-bell." He sailed for the Bahamas, but was not able to find the spot where the vessel lay. He received information of another, however, the position of which was more accurately defined, and which held a much greater treasure.