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would still be seen for ten years after the catastrophe. Remember that light travels 191,000 miles in a second, that there are 86,400 seconds in a day, and 365 1-4 days in a year. The product of these three numbers, multiplied by ten, gives us the distance in miles which separates us in a straight line from 61 Cygui. Astronomers may well boast of such a result, and desire to apply their magnificent measuring operations to other stars.

Large telescopes, of parallactic mounting and high maguifying power, will serve to perfect the observations upon the double stars. It is now known that the stars of nearly all these binary groups are dependent upon each other; they form systems composed of suns, usually colored, and turning around their common centre of gravity. The exact measurement of these movements of rotation, combined with the determination of the actual distance of the two stars, will lead mathematically to a knowledge of the sum of the two masses. When mathematicians and astronomers were enabled to prove with absolute certainty, that the mass of the sun is 355,000 times as great as that of the earth, every one was struck with astonishment. But the result was by no means so wonderful or so difficult of attainment as the one now proposed. Then, the problem was to ascertain the bulk of a heavenly body which appears even to the naked eye as a vast globe, around which the earth revolves, and which governs by its attraction, —that is, by an action dependent on its mass, — all the planetary movements. Every one can here dimly perceive a priori connections and relations which ought to lead to the desired result. Now, the object is to ascertain the bulk of suns belonging to other systems; of suns placed at such distances as to confound the imagination; of suns which appear, even through the telescope, of no appreciable diameter; of suns which the mere thickness of a spider's thread veils from the eye of the observer. Here the force of science will appear in all its majesty.

With such a telescope as we now speak of, astronomy will find a field of research, as yet almost untouched, in the vast arid variously shaped nebula, which are scattered all over the heavens. It will observe the gradual concentration of the phosphorescent matter; it will mark the epochs when it assumes a circular shape, when the luminous central nucleus first appears, when this nucleus, having become very bright, will remain surrounded only by a slight nebulous halo, and when this halo also will be condensed. Then, the observer will have followed through all its phases the birth of a new star. Another quarter of the heavens will show us how the same stars gradually grow faint, and at last entirely disappear.*

Within the limits of our own system, also, a great telescope promises discoveries of another kind, and of no inferior interest. We yet know but little of the atmosphere of Venus, or of the lofty mountains withjwhich this

* The truth of the rutndir hypothesis is here taken for granted; but if the recent "accounts of discoveries mode through Lord Rosse's telescope are correct, this hypothesis is only a splendid drcain.

globe, nearly as large as the earth, appears to be covered. The snowy spots which periodically appear, increase, diminish, and disappear, first at one, and then at the other pole of rotation of Mars, according as the sun is in this or that hemisphere of the red planet, have not been sufficiently studied. Though Jupiter has not yet been carefully examined with powerful telescopes, we know that in the equinoctial regions of this planet there are winds like our trade-winds; that the atmosphere there undergoes enormous perturbations; and that clouds there are sometimes borne along at the speed of 250 miles an hour. If these curious results have been obtained with our present imperfect means of observation, what may we not expect from diligence united with power? The mysterious ring of Saturn, — that continuous bridge without piles, 30,000 miles broad, 250 miles thick, and everywhere distant 20,000 miles from the planet which it surrounds, — certainly reserves capital discoveries for one who can examine it continuously with a high maguifying power. The continued observation of the brilliant satellites of Jupiter has so enriched science, that we may reasonably expect much from an uninterrupted examination of the satellites of Saturn and Uranus. A study of the continual changes of form which comets undergo ought to enlighten us respecting the physical constitution of celestial space. If these inquiries as yet have made but little progress, the fault must be imputed to the feebleness of our telescopes.

Let us now take a rapid view of what may reasonably be expected from the application of much unproved instruments to the observation of the Moon. 1,093 mountains upon its surface have been exactly measured. One of these lunar mountains, Doerfd, is 25,000 feet high; another, Newton, is 24,000 feet; a third, Casatus, is 22,500 feet. The crater-like formation of most of the moon's surface, also, has been carefully observed; the depth of each crater and the altitude of the central peak are now exactly known; and astronomers have obtained these results with a multiplying power not exceeding 200. May we not have great hopes, then, of a telescope the illumination of which will permit us to use a multiplying power of 6,000, and through which we can observe a lunar mountain as fully as we now can see Mont Blanc from Geneva? In 1843, Dr. Robinson examined the moon with a reflecting telescope, three feet in diameter, belonging to Lord Rosse; its illumination was only one fourth as great of a refractor of three feet opening, and the multiplying power was but moderate. Yet this astronomer has already pressingly invited the naturalists to go to Rirsontown in Ireland, in order to study the physical constitution of the moon, assuring them, that they would gain entirely new information respecting the action, upon our globe, of the forces which govern the formation of volcanic regions.

If, after this long exposition of the uses of great telescopes, the Chamber will also remember that, in such a case, the unexpected discoveries are always the most numerous, most fruitful, and most brilliant, it will see why its. Committee unanimously recommends, that an appropriation of $19,000 should be made for completing the Observatory of Paris.

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II. METEOROLOGICAL TABLES FOR CAMBRIDGE. Mass.

Summary of the Meteorological Obsercations made at the Obsercatory of Harcard College. By W. Cranch Bond. North Lot. 42' 22'. Lon. Wtst of Greenwich, 71° 07'. From May 1st, 1844, to May 1st, 1846.

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* Melted snow since November.

Barometer was highest, 1844, October 22. 30.522 in. Lowest, February Bth, 1845, 28.882. Range. 1.740. Mean for the year, 29907.

Thermometer highest, 1844, August 17th, +90'. Lowest Feb'y 2d, 7.9. Range, 97.9. Mean temperature for the year, 47.2 .

Maximum of Thermometer, 1845, .Inly 12, +100°. Minimum of Thermometer, 1848, February 27th,—8. Range, 108 Mean for the year, 29.920 in.

Barometer was highest, 1845, November 29th, 30.580. Lowest. February 20,1846,29.080. Range, 1 500. Mean temperature of the year at the hours, 48.9'.

The hours of observation adopted in these tables, arc t!iose generally used by observers in England. The mode of notation for the wiuds and clouds also deserves notice. In the former case. 0 denotes a perfect calm, and 6 the greatest violence of the wini. In the latter case. 0 denotes a sky without any clouds, and 10 u sky completely overcast. As uniformity in tliese tables is very desirable, it is to be wished that this method should be adopted by observers throughout the country.

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