though it has been travelling ever since the creation at the rate of 200,000 miles in each second of time. Dr. Halley has also advanced, what, he says, seems to be a metaphysical paradox, viz., that the number of fixed stars must be more than finite, and some of them at more than finite distances from others and Mr. Addison has observed, that this thought is far from being extravagant, when we consider that the universe is the work of Infinite Power, prompted by infinite goodness, and having an infinite space to exert itself in, so that our imaginations can set no bounds to it. Magnitude of the fixed Stars.-The magnitudes of the stars appear to be very different from one another; which difference may probably arise, partly from a diversity in their real magnitude, but chiefly, no doubt, from their distances, which are different. To the bare eye the stars appear of some sensible magnitude, owing to the glare of light arising from the numberless reflections from the particles floating in the atmosphere, which makes us imagine the apparent diameters of stars to be much larger than they would appear if we saw them only by the few rays which come directly from them. This may be made evident to any person by looking at a star of the first magnitude through a long narrow tube; which, though it takes in as much of the sky as would hold a thousand such stars, scarcely renders one visible. With respect to the parallax of the fixed stars, Dr. Herschel observes, that various methods have been pursued without success, and the result of the finest observations has hardly given us more than a distant approximation, from which it may be concluded that the nearest of the fixed stars cannot be less than 40,000 diameters of the Earth's annual orbit distant from us. Trigonometry, by whose powerful aid the mathematician has boldly ascended into the planetary regions, and measured the diame ters and orbits of the heavenly bodies, for want of a proper base, can here be of little or no service; for the whole diameter of the annual orbit of the Earth is a mere point when compared to the immense distance of the stars. On this subject, Dr. Herschel has a very curious paper in vol. lxxii of the Philosophical Transactions, which, however, does not omit of being sufficiently abridged for the purposes of our volume. The author observes, he was fully satisfied that, in the investigation of parallax, the method of double stars would have many advantages above any other; it therefore became necessary to look out for proper stars for this purpose. This introduced a new series of observations. I resolved,' says the Doctor, to examine every star in the heavens with the utmost attention, and a very high power, that I might collect such materials for this research as would enable me to fix my observations on those that would best answer my end. I took some pains to find out what double stars had been recorded by astronomers; but my situation did not permit me to consult extensive libraries, nor, indeed, was it very material; for, as I intended to view the heavens myself, Nature, that great volume, appeared to me to contain the best catalogue on this occasion. However, I remembered that the star in the head of Castor, that in the breast of the Virgin, and the first star in Aries, had been mentioned, by Cassini, as double stars. I also found that the nebula in Orion was marked, by Huygens, as containing seven stars, three of which, now known to be four, are very near together. With this small stock I began, and, in the course of a few years' observations, have collected the stars contained in my catalogue.' Dr. Herschel divided the double stars into several different classes: in the first he placed all those which required a very superior telescope, the utmost clearness in the air, and every other favourable circumstance to be seen at all. These, he says, seemed to deserve a separate place, that an observer might not condemn his instrument or his eye if he should not be successful in distinguishing them. Since it will require no common stretch of power and distinctness to see these double stars, it will not be amiss to go gradually through some preparatory steps of vision, such as the following: when Corona borealis, one of the most minute double stars, is proposed to be viewed, let the telescope be directed, for a time, to a Geminorum, or 2 Aquarii, Draconis, e Herculis, a Piscium, or the curious double-double star & Lyræ. These should be kept in view a considerable time, that the eye may acquire the habit of seeing such objects well and distinctly. The observer may next proceed to Ursæ majoris, and the beautiful treble star in Monoceros' right fore-foot ; after these to Bootes, which is a fine miniature of a Geminorum, to the star preceding & Orionis, and to Orionis. By this time both the eye and the telescope will be prepared for a still finer picture, which will be found in ห Coronæ borealis. All these may be seen with a telescope that magnifies something more than 220.. Dr. Herschel, in the second class of double stars, has put all those that are proper for estimations by the eye, or very delicate measures of the micrometer. To compare the distances with the apparent diameters, the power of the telescope should not be less. than 200, otherwise they will be too close for the purpose. In the third class he places all those double stars that are more than 5" but less than 15" asunder; and, for that reason, if they should be used for observations on the parallax of the fixed stars, they ought to be considered as quite free from the effects of refraction. In the same manner that the stars in the first and second classes will serve to try the goodness of the most capital instruments, these will afford objects for telescopes of inferior power, such as magnify from 40 to 100 times; they are to be taken in the following order, Ursæ majoris; y Delphini; Bootes; y Virginis; Cassiopeia; Arietis; μ Cygni. The fourth, fifth, and sixth classes contain double stars, that are from 15" to 30", from 30′′ to l', and from 1' to 2', or more, asunder. Dr. Herschel's catalogue of double stars is to be found in vol. Ixxii of the Philosophical Transactions, and in vol. xv of Dr. Hutton's Abridgment. This catalogue contains 269 double stars, of which the Doctor says, 227 had never been noticed before. I hope,' says he, they will prove no inconsiderable addition to the general stock, especially as in that number there are a great many which are out of the reach of Mr. Mayer's and other mural quadrants, or transit instruments. It can hardly be expected that a power of 70 or 80 would be sufficient to discover those curious stars that are contained in the first class of my catalogue; so that it is not strange they should have entirely escaped Mr. Mayer's notice. We see that it is not for want of his looking at those stars; for he has frequently observed Cancri, the star near Procyon, and the star in Monoceros, without perceiving the small stars near them, which I have pointed out. Nor is it only in the first class that his telescope wanted power, light, and distinctness, for the small stars that are near ß Orionis, ß Serpentis, ? Orionis, & Pegasi, a Lyræ, & Andromedæ, μ Sagittarii, a Aquila, Pegasi, & Lyræ, and many more, have escaped his discovery; though he has given us the places of other more distant small stars not far from them, and, therefore, must have had them frequently in the field of view of his telescope.' n [To be continued.] Astronomical Occurrences. THE Sun enters the sign Libra on the 23d, at 43 m. past 4 in the morning. On the 7th, at 35 in. past 2 in the morning, Venus and Mars will be in conjunction, Mars being 28' south of Venus. On the 21st, at 1 m. before 3 in the morning, Mercury will be in conjunction with Spica m, the star being 28' south. Sept. 1, from the time on the dial subtract 0 12 1 49 3 31 5 16 8. 43 To obtain true time by the clock, 26, The Moon is full on the 6th day of September, at 22 m. past 4 in the afternoon: she enters her last quarter on the 14th, at 47 m. past 7 in the evening. It is new Moon, or change, on the 21st, at 3 m. past 3 in the afternoon; and she enters her first quarter on the 28th, at 25 m. past 8 in the morning. The eclipses of Jupiter's satellites are not visible in London and its neighbourhood during this month. The Naturalist's Diary. SEPTEMBER comes to cheer the fowler's heart, SEPTEMBER, like the following month, often boasts many fine days, at least till the commencement of the |