It is worthy of remark, that tales of ancient times must be received with caution. We find it necessary, even at a much later period. The tricks which now amuse or astonish the populace at a country fair, would be greatly exaggerated in a credulous age, and often assume even the most portentous colouring. Nor is it difficult to guess, and sometimes to discover, the stages of similar and great mystifications. The following instance is rather remarkable. On Charles V. entering Nuremberg, a celebrated German astronomer, whose real name was Johann Müller, but who styled himself Regiomontanus, exhibited some automata which he had constructed. These were an eagle of wood, which, placed on the gate of the city, rose up and flapped its wings, while the emperor was passing below; and a fly, made of steel, which walked round a table. Now all this is sufficiently credible. But what is the record of the chroniclers only a few years after? That the wooden eagle sprang from the tower and soared in the air; and that the steel fly flew three times round the emperor, and then alighted buzzing on his hand! In many instances, the mechanism of modern times is surprisingly minute. A watchmaker in London presented his majesty George III. with a repeating watch he had constructed, set in a ring. Its size was something less than a silver two-pence; it contained one hundred-and-twenty-five different parts, and weighed, altogether, no more than five pennyweights and seven grains! In an exhibition of Maillardet, which the writer has seen, the lid of a box suddenly flew open, and a small bird of beautiful plumage started forth from its nest. The wings fluttered, and the bill opening with the tremulous motion peculiar to singing birds, it began to warble. After a succession of notes, whose sound well filled a large apartment, it retired to its nest, and the lid closed. Its performances occupied about four minutes. In the same exhibition were an automatic spider, a caterpillar, a mouse, and a serpent; all of which exhibited the peculiar movements of the living creatures. The spider was made of steel: it ran on the surface of a table for three minutes, and its course tended towards the middle of the table. The serpent crawled about in every direction, opened its mouth, hissed, and darted forth its tongue. Several years ago, a watchmaker, residing in a town in which the writer lived, made a working model of a steam-engine, the packing-case of which was a walnut-shell. On showing it one day to a gentleman, the machine was suddenly stopped, the mechanic remarking, “There is something wrong in one of the safety-valves.” “Safety-valve!” exclaimed the observer; “I have not yet been able to detect the fly-wheel!”