Page images
PDF
EPUB

transverse diameter of the ellipsis, intersecting the ellipsis in the corresponding points. Through the degree and minute in the circle answering to the star's A.R. draw a diameter, and from the place of the moon's node in the ellipsis measure the shortest distance to this diameter passing through the star's A.R. and apply it to the scale of the radius; then this length multiplied by the natural tangent of the star's declination, will give the nutation in A.R. in seconds of a degree.

Hold the place of the star from you, and if the place of the moon's node be on the right hand of the diameter passing through the A.R. of the star, the nutation is additive, but if on the left, subtractive. The equation of the equinoxes, taken from the tables, is to be applied to the nutation in A.R. according to its sign in the tables, and the sum or difference will be the correction in A.R. of the star.

FOR THE NUTATION OR DEVIATION OF A STAR IN

DECLINATION.

Make a similar projection with the former, only let the graduations of both ellipsis and circle begin at the right-hand extremity of the transverse axis of the ellipsis; and proceed towards the left, as before. The nearest distance from the place of the moon's ascending node in the ellipsis, to the diameter passing through the place of the A.R. of the star, measured as before, is the nutation in declination in seconds.

This nutation is additive for a northern, and subtractive for a southern star, if the place of the moon's ascending node be on the right hand of the diameter passing through the A.R. of the star, but the contrary, if on the other side, when the place of the star is held from you.

CONCLUSION.

Now, in the conclusion, when we consider the prodigious magnitude of the space in which the fixed stars are placed, it does not seem probable, that such vast bodies as they must necessarily be, were created for no other purpose, than to afford us a glimmering light in the absence of the sun. If this were the sole intention of their existence, why have the telescopic stars twinkled unseen by any mortal, till the invention of the telescope? or why is their number proportioned to the goodness of the telescope; more being seen continually, as that useful instrument receives a higher improvement? Certainly the supposition is inconsistent with the adequacy of the Infinite Agent to the effect. As there is reason to believe from the discoveries of the telescope, that not one half, nay, it may be, not a thousandth part of their number has ever been seen by any mortal; and that their distances from each other cannot be less, than the distance of some of them from us; this distance must be inconceivably magnified before we can have any conceptiops of the dimensions of the creation. The incomprehensible Creator alone can comprehend the unbounded expansion. Here our observations fail, and we are reduced to hypothesis. The most probable design of their existence, is derived from this consideration; that none of them have any parallax, and consequently that if the annual orbit of the earth, which is near 200 millions of miles in diameter, were viewed from the nearest of them, it would not subtend an angle of a single second; and therefore if our sun were removed to the same distance, he would appear no larger than a shining point; and our whole planetary system must become absolutely invi

sible to such eyes as ours. Hence it is extremely probable, that every one of this countless multitude of stars was ordained for similar purposes with our sun; and that they are the central sun's of innumerable systems, distributing the various influences of light and heat to their attending planets; whose immense distance from us, must for ever conceal them from the human eye.

THE END.

[subsumed][merged small][merged small][subsumed][merged small][merged small][subsumed][subsumed][subsumed][subsumed][merged small][merged small][merged small][graphic]
[merged small][merged small][ocr errors][merged small][ocr errors]
« PreviousContinue »