In this observatory there was, according to one of the best Mahomedan works, a species of apparatus to represent the celestial sphere, with the signs of the zodiac, the conjunctions, transits, and revolutions of the heavenly bodies. Through a perforation in the dome, the rays of the sun were admitted, so as to strike upon certain lines on the pavement in a way to indicate, in degrees and minutes, the altitude and declination of that luminary during every season, and to mark the time and hour of the day throughout the year. The Observatory was further supplied with a map of the terrestrial globe, in all its climates or zones, exhibiting the several regions of the habitable world, as well as a general outline of the ocean, with the numerous islands contained in its bosom; and, according to the Mahomedan author, all these were so perspicuously arranged and delineated, as at once to remove, by the clearest demonstration, every doubt from the mind of the student. ------------------ LONDON AS A PORT. Sir John Herschel, who possesses in an eminent degree, the peculiar talent of felicitously illustrating every subject that he approaches, in his valuable _Treatise on Astronomy_, thus refers to the situation of London as a Port:--"It is a fact, not a little interesting to Englishmen, and combined with our insular station in that highway of nations, the Atlantic, not a little explanatory of our commercial eminence, that LONDON _occupies nearly the centre of the terrestrial hemisphere_." ------------------ FOURDRINIER'S PAPER-MAKING MACHINERY. On April 25, 1839, some very interesting details of Fourdrinier's Machinery for making Paper of endless length, were elicited during a debate in the House of Commons, upon the presentation of a petition from these ingenious manufacturers. It appears that 1000 yards, or any given quantity of yards, of paper could be continuously made by it. Many years since, the invention was patented; but, owing to a mistake in the patent--the word "machine" being written instead of "machines"--the property was pirated, and that led to litigations, in which the patentees' funds were exhausted before they could establish their rights. They then became bankrupts, and thus all the fruits of their invention, on which they had spent 40,000_l._, were entirely lost to them.