SEEKING FOR COMETS.

New Zealand Spectator and Cook's Strait Guardian, Volume XIII, Issue 1371, 22 September 1858, Page 4

SEEKING FOR COMETS.

The great observatory at Harvard College was established in 1847. Among tbe many brilliant discoveries made there since its establishment, are no less than fourteen comets. Nine were discovered by the indefatigable labours of Mr. George P. Bond. The tenth was discovered in March, 1853, by Mr. Charles IV. Tuttle. Tbe remaining four by Mr. Horace P. Tuttle.

Few persons are aware of the patience and labour exercised by the astronomer in making discoveries of this kind. It requires several years’ study and practice to qualify one to discover a telescopic comet. It is’undoubtedly very easy to look at a comet already visible to the naked eye in the heavens; but when it is desired to disco, ver an unknown one, wandering in its “ long travel of a thousand years” in the profound abyss of space, the labour then becomes truly prodigious. The amount of physical suffering occasioned by exposure to all kinds temperature, the bending and twisting of the body when examining near the zenith, and the constant strain of the eye, cannot be fully understood and appreciated by one unacquainted with an astronomer’s fife.

The astronomer, with his telescope, begins at the going down of the sun, and examines, in zones, with the utmost care and vigilance, the starry vault, and continues till the "circling hours” bring the sun to the eastern horizon, when star and comet fade from bis view. It requires several nights to complete a thorough survey of 'h= heavens; and often these nights do not follow in succession, being interrupted by the full moon, by clouds, auroras, and by vaiious other meteorological phenomena. He is frequently vexed by passing clouds, fleeting through the midnight sky, and strong and chilly breezes of the night. His labours are continued throughout the year, and bis unwearied exertions do not slacken during the long wintry nights, when the frozen particles of snow and ice, driven before the northern blast, cause the star to sparkle with unusual lustre, and his breath to congeal on the eye-piece of the telescope. It frequently happens that his labours are not crowned with a discovery until after several years' search. Nothing can exceed the sublime spectacle presented to the astronomer under a clear midnight sky, as he sweeps athwart the gorgeous constellations in their " starry dance" around their appointed centre. Occasionally the field of the telescope is filled with the dazzling radiance of unnumbered sums of a variety of rich and beautiful colours. The field of tbe telescope is olten illuminated by the sudden transit of a far-off meteor, invisible to the naked eye. Sometimes a large one falls fiom the zenith, and silently exploding. fills the midnight sky with a startling spectral light. The solitude and silence of the night is broken in spring, summer, and autumn by the low murmuring voices of migrating birds’ and the half-suppressed buffeting of their weary wings, which darken for a moment tbe field of the telescope in the flight. These are the only living companions of lhe astronomer afloat in the sky at midnight.

There is a momentary excitement when his wearied eye detects a small wisp of pale scattered •light in the field of his telescope. J t j s V erv comet-like, but I e does not feel quite sure that he is not tantalized with a nebula—a cluster of suns—SO remote as to defy the utmost power of assisted vision to resolve it into its individual components. He immediately ascertains the exact position, and examines the catalogues for information of its character. If it is unrecorded, he is obliged io bring the wondrou-s mechanism of human hand to his assistance. The sidereal clock, and the minutely graduated circles of his telescope, inform him of his right ascension and declination. Usually the distance of tl le unknown body is rigorously measured by the mitt ometer, —a work of unsurpassed delicacy from a star in the same field. Al lhe end of several liours his labours are rewarded by the discovery of u new nebula, or the slow but decisive motion

of a new comet. It is a moment of intense feeling. A new globe has hove in sight from tbe utmost bound of human vision. Whither has it come? und whither is it going? What is its distance from the earth and from lhe sun ? When will it be nearest to lhe earth, mid when lo the sun? What is its velocity and magnitude? Will it ever become visible to tbe naked eye? and lias it ever before appeared within the memory ol man, on the tecords of history? These ate questions that be cannot immediately answer. His mind, aided by the most powerful analysis, penetrates into the secret workings of the inlii'iie mind, and by a mysterious process revolves trie answers to bis queries. Three complete observations, made on three different days, or longer intervals of time, furnish him with the basis of his calculations of the unknown par'iculars of the comet. They are technically called the elements of its oi bit. With these three great celestial marks, he proceeds to the calculation of the elements, a work of exceeding great labour and difficulty. It is a problem of pure geometry ; and the illustrious Newton, who fist solved this gigantic problem and applied it to the great comet of 1680, pronounced it " Problema longs difficilimtun.” A distinguished American astronomer of tbe last cemury, Rittenhouse, of Philadelphia, was tbe first American that solved tbe problem. He computed the elements of the comet of 1770, and says of it, in a letter to the President of the American Philosophical Society, "Herewith,l send you the fruit of three or four days’ labour, during which I have covered several sheets, and literally drained my inkstand several times. Our celebrated countryman aod neighbour, Dr. Bowditch, computed the elements of tbe great comet of 1807, and tbe greater one of 1811, the latter yet remembeted by all our aged citizens, as it appeared in the autumnal months of that year, which “Burned In the arctic sky, and from its horrid air Shook pestilence and war.”

In 1849 tbe learned world in America and Europe Was astonished at the production of the elliptic elements of the first comet of that year, bv the wonderful Stafford, then only founeeu years of age. No mathematical genius in the history of our race has ever achieved such an honour at so early an sge.

Tbe late King of Denmark, a great patron of astronomy, in the last years of his life, decreed that a gold medal should he awarded to the first discoverer of a comet. Miss Maria Mitchell of Nantucket discovered a comet in October 1847, and received therefore a comet medal, and was further honoured by being made a member of the American Academy of Arts and Sciences. The King soon after deceased, and bis successor appropriated his revenues to other purposes. The discontinuance of the Denmark rnadel has not iu the least degiee abated the zeal ol the astronomers. Tbe discovery of the same er met by different astronomers in different parts of the world on the same night, or within a few days of each other, attest their Unremitting vigilance.—Newburyport Herald.