MIGRATION OF BIRDS. Dr. Schinz, Secretary to the Provincial Society of Zurich, has endeavoured to discover the laws according to which the birds of Europe are distributed over our continent. The country in which the bird produces its young is considered as its proper one. The nearer we approach the poles, the more do we find peculiar or stationary birds, and the fewer are the foreign species which make their appearance. Greenland has not a single bird of passage. Iceland has only one, which remains during winter, and leaves it in spring for still more northern countries. Sweden and Norway have already more birds of passage; and we find them increasing in number in proportion as we advance towards the centre of Europe. In the intertropical countries no bird emigrates; to the north they all emigrate. The propagation of birds keeps pace with the quantity of food. Spitzbergen has but a single herbivorous species; for the sea presents more nutriment, and all the rocks and cliffs are inhabited by aquatic birds. In the frigid zone a much greater number of marsh birds breed than beyond the arctic circle and in the warm countries of Europe. Dr. Schinz also indicates the distribution of the species of domestic fowls, and remarks that each country has its peculiar varieties of fowls.* -Bulletin Univers. UNIVERSAL MERIDIAN. "It is very desirable," M. de la Place observes, "that all the nations of Europe, instead of referring their calculations of longitude to the meridian of their principal observatory, should have some common meridian, which nature seems to have pointed out for that purpose. That agreement would introduce into the geography of the world the same uniformity that exists in its almanacks For Dr. Jenner's investigation of the circumstances which impel birds to migrate, see the Philosophical Magazine, vol. Ixiv. page 50. and in its arithmetic; a uniformity which, extending to the numerous objects of their mutual relations, forms various countries into an immense family." M. de la Place proposes that either the Peak of Teneriffe or Mont Blanc should be the point through which this common ineridian should pass. NOTICES TO CORRESPONDENTS. Fides Defensor has overlooked a notice intended for him several weeks ago. We must still decline resuming the controversy. We shall endeavour, in a short time, to send J. R. the information he desires. T. M. B. and Aurum, on Philological Discussions, caution wisely; but the insertion of their communications would only prolong what they deprecate. The subject treated of by Viator shall certainly be taken up in our next, Communications are received from-A Subscriber-A. S. H.-S. W.-H. H. H. -H.-J. Firth-Q. S.-W. Smith-David-W. C.-T. L. C. Advertisements for the Covers of the Monthly Parts must be sent to the Publishers before the 20th day of each Month. Communications (post paid) to be addressed to the Editor, at the Publishers', KNIGHT and LACEY, 55, Paternoster-row, London. Printed by Mills, Jowett, and Mills (late Bensley), Bolt-court, Fleet-street. 50 FIRST TRANSIT OF VENUS, ETC. VACUUM POWER ENGINE. SIR,-Following up the idea of your Correspondent, Z, in the 130th Number of the Mechanics' Magazine, I have devised a method of obtaining a Vacuum under the piston of an Engine of similar construction to the atmospheric steam-engine. It is simply this: A and B are two cisterns of water, the level of the water in the cistern A, being four feet above that of the water in the cistern B; c and d are valves, which are opened and shut by the rods gg. When the valve d is open, water rises into the cylinder through the pipe, K, from the cistern A, by the pressure of the atmosphere, as high as the dotted line, A, which is 32 feet above the surface of the water in the cistern A; now the valve d being shut, and the valve C open, the water will fall to the dotted line B, that being 32 feet above the surface of the water in the cistern B, thereby producing a vacuum in the cylinder beneath the piston, or in the space between the dotted lines A and B. The piston, now having the whole pressure of the atmosphere upon it, will descend with a force proportionate to its area, bringing down the end of the beam with it. The piston being now at its lowest point, the rods, gg, will have opened, in their descent, the valve d, and closed the valve c. The water will now rise, by the pressure of the atmosphere, through the pipe K, and regain its height in the cylinder to the dotted line A, while the momentum of the fly-wheel raises the piston. When the piston has reached its highest point, the rods, gg, will have opened the valve c, and shut the valve d, and the piston will again descend, the water which produced the vacuum passing off through the pipe, L, into the cistern, B. The cistern, A, is supplied with water from the pipe, E, which has a ball-cock, to preserve the level of the water. The pipe, F, allows the superfinous water to run off from the cistern, B, and thus preserves the same level of water in that vessel. Before the engine can be set in motion, the plug at F must be taken out, the pipes L and K, and the cylinder, filled with water; replace the plug, and shut the valve, d, and the motion commences. It is obvious that the height of the level of the water in A, above that of the water in B, will be the length of the stroke of the piston. this subject in a very hasty manner, Your most obedient servant, Portsmouth, FIRST TRANSIT OF VENUS. The first time the transit of Venus over the sun's disc was visible to mortal eyes was on the 24th of November, 1639, and the only two persons in the world who then observed it were Mr. Horrox, a young astronomer of great talents, who predicted its appearance, and his friend Mr. Wm. Crabtree, to whom alone he had ventured to announce the discovery. How enviable must have been the delighted feelings of these two young friends, at the moment when their solitary anticipation was realized! Mr. Horrox, who was suddenly cut off in the 22nd year of his age, was also the author of a Theory of Lunar Motions, which Newton has made the groundwork of his Astronomy, but not without a proper acknowledgment of the claims of this extraordinary young man, whom he always spoke as a genius of the first rank. of ERRORS IN DR. HUTTON'S TABLES OF THE PRODUCTS AND POWERS OF NUMBERS. Mr. James Utting has discovered no less than 1700 errors in one page (the 20th) of Dr. Hutton's Tables of the Products and Powers of Numbers. The products of all numbers from 361 to 380 at the head of the table, by 15 to 99 at the side, are all 100 too little. Hence 9957: 9096 :: 43: 39 .45980+39.46019 is the approximate 89 93 99 27 = 3.375. 82 The tabular equation is ys 52 SCYLLA AND CHARYBDIS. Opposite to 3.7 we find a1 3.8...... at Difference...... Corrections. .41713 .41892 179 = 3.28287 = 3.38108 9821 poetry can seldom bear to be shackled by homely truth; and if we are to receive the fine imagery that places the summit of this rock in clouds, brooding eternal mists and tempests; that represents it as inaccessible even to a man provided with twenty hands and twenty feet, and immerses its base among ravenous sea-dogs; why not also receive the whole circle of mythological dogmas of Homer, who, though so frequently dragged forth as an authority in history, theology, surgery, and geography, Also 3.375-3.28287-9213 ... 9821 ought, in justice, to be read only as : 9213: 179: 168 :: 41713+ 168 = .41881. a poet. In the writings of so excellent a hard we must not expect to find all his representations strictly Hence y=3.375 + .41881 = 3.79381; confined to a mere accurate narration and x = 8 x 3.79381 = 3.37228. 9 The negative root of the equation 23-9x=-8 is-3.37228; and all these figures we have found to be correct by the method of approximation. Cubic equations of the form x3± qa [ x2 ± r = 0, very often occur for solution; they may be reduced to the tabular form without taking away the second term, as follows:: of facts. Moderns of intelligence, in visiting this spot, have gratified their imaginations, already heated by such descriptions as the escape of the Argonauts and the disasters of Ulysses, with fancying it the scourge of seamen, and that, in a gale, its caverns roar like dogs;" but I, as a sailor, never perceived any difference between the effect of the surges here and on any other coast, yet I have frequently watched it closely in bad weather. It is now, as I presume it ever was, a common rock of base, and surmounted by a castle, bold approach, a little worn at its with a sandy bay on each side. The one on the south side is memorable for the disaster that happened there during the dreadful earthquake of 1783, when an overwhelming wave (supposed to have been occasioned by the fall of part of a probeach, and, in its retreat, bore away montory into the sea) rushed up the with it upwards of 2000 people, whose cries, if they uttered any, in the suddenness of their awful fate, were not heard by the agonized spectators around. Outside the tongue of land, or Braccio di St. Rainierè, that forms the harbour of Messina, lies the Salofaro, or celebrated vortex of Charybdis, which has, with more reason than Scylla, been clothed with terrors by the writers of antiquity. To the undecked boats of the Rhegians, Locrians, Zancleans, and Greeks, it must have been formidable; for, |