By the advice of his friends, Dr. Brewster took out a patent for his invention; in the specification of which he describes the kaleidoscope in two different forms. The instrument, however, having been shown to several opticians in London, became known before he could avail himself of his patent; and, being simple in principle, it was at once largely manufactured. It is calculated that not less than 200,000 kaleidoscopes were sold in three months in London and Paris; though, out of this number, Dr. Brewster says, not, perhaps, one thousand were constructed upon scientific principles, or were capable of giving anything like a correct idea of the power of his kaleidoscope. ------------------ LORD ROSSE'S LEVIATHAN TELESCOPE. The late Earl of Rosse, with a devotion to science which has few parallels, constructed this gigantic telescope, at his seat, Parsonstown, in the south of Ireland. To the frame of the vast instrument is fixed a large cubical wooden box, about eight feet wide; in this there is a door, through which two men go in to remove, or to replace, the cover of the mirror. To this box is fastened the tube, which is made of deal staves, and hooped like a huge cask. It is about 40 feet long, and 8 feet diameter in the middle. _The Dean of Ely once walked through the tube with an umbrella up!_ The stupendous speculum weighs three tons; the casting and polishing of it were labours of wonderful skill. The telescope is not turned to any part of the sky, but limited to the range of half an hour on each side of the meridian, through which its motion is given by powerful clockwork, independent of the observer. For this purpose it stands between two pieces of masonry, of gothic design, which harmonize with Lord Rosse's castle; one of these piers sustaining the galleries for the observer, and the second the clockwork and other apparatus. There is an elegant arrangement of counterpoises to balance the enormous mass, so that a comparatively slight force only is required to elevate or depress it. A correspondent of the _Mechanics' Magazine_ thus describes the capacity of this wonderful instrument:--