THE COMET.

Auckland Chronicle and New Zealand Colonist, Volume 1, Issue 28, 25 March 1843, Page 1

THE COMET.

[communicated.]

Though the motions of comets have long ceased to be ait enigma to the philosopher, and though they are consequently no longer regarded with superstitious horror, yet, will the remarkable ones be always looked upon with feelings of awe and astonishment; The heart has its natural objects as well as the understanding ; and those objects will excite the feelings which the author of our nature has made correspondent, to thenr, hi ties pite of any conceivable improvement in the intellectual part of our nature;, and it despite of that'frigid philosophy, which would perstiade us that the tijOvements of the heart are *o many imperfections, that the human SDtd Should be reduced to reason wituuut pas&ioii, to thought without feeling.

The magnificent object which is now visible in our gxieft in Uie commencement of the night is, from the suddenness with which it burst upon us, from its brilliancy, and, above all,* from the vas-t w Irish it cVu i. s about with it, .).■!<> of lite y,ia?idcsi of uatiiml phenomena, .rod <Hi!i!cntiy calculated to awake in cve-,v t.,i;id, not st id lifted i y false or su • j.'Ot'ic'hti ; biloS'»i>hy, those sentiments ol avcy iind aJitiir.itim 'to which we adveited above, 'jiif people of Auckland accord ingly coHthnie, night after nighty rergaae upon this "land spectacle with unabated eft.J.|M?sii»iiSs\ In the intervals between its appearances;, when their eyes can be no longer gr.iiifted, and emotion is succeeded by.it faction, they naturally become curious concerning thw luws by which the appa i"«rtitiy irregular and capricious motions of these extraordinary" bodies are governed; eou-eerning the history, but particularly

concerning the speculations of philosophers about their tails, about their own intimate natine, and the functions which they perform in the economy of the planetary system of which they form a part. It is with 'he view of, in some degree, gratifying jhe curiosity of those amottgst us who havf rrq d.iing miikls, but no uccess'to boi k< o! astronomy, in this their infant and ado >ted country, that we will, in this, and some future numbers of this journal, touch briefly upon these dijfferent subjects in the tfrrfei in which they have been mentioned..

Let us imagine the bodies which com pose the planetary system to have just come into existence fresh from the hands of their Creator, placed in different parts of space, in a state of quiescence, and. subjected to the action of no other forces than their own attractions. In this case they would, by virtue .of.,their mutual actions, instantly begin to approach each other, would finally meet in their common centre of gravity, and there for ever remain one quiescent mass. The present motions of the bodies of our system are the resul's of two causes—their own mutual attractions, and certain impulses impressed upon them at the moment of their creation by the Almighty arm. It was demonstrated by Newton, that /wo bodies, with primitive impulses impressed upon them, and afterwards resigned to (heir mutual action, would describe both round one another, and round their common centre of gravity, some conic section, viz , an ellipse, circle, parabola or hyperbola, and that the particular form of conic section which each would describe, would depend upon the amount of the velocity communicated to it by the primitive impulse, and the direction of that veioejt, with respect to the line joining the t o bodies. It was demonstrated by the'satna philosopher, that in the case of afty number of bodies, one of which is so very large, thai the proportions of the others to it are quite inappreciable, all having primitive impulses impressed upon them, aud being subjected to the action of no other forces than their own mutual attractions, each of the smaller bodies would describe very nearly a conic section about the large one, the /particular form of » inch would in each case depend upon the circumstances above mentioned in the case of two bodies. This is precisely the case of our system, the mass of Jupiter, the largest of our planet*, being scarcely the thousandth part of the mass of the sun. The planets and the earth revolve from west to east, in elliptic orbits, round the sun which occupies one of the foci of each eclipse, the eccentricities of the orbits being tiery small or in other words, their forms being neatly circular, and tha inclinations of the planes of the orbits of the planets to that of the earth (the ecliptic) being very slight, The motions of the comets are regulated by the same general laws as those of the planets, with only the following circum stunt rat variations. The ellipses which they describe about the sun are not, like

those of the planets, nealy circular, but, on the contrary, -»o immensely elongated, that their motions may be sufficiently well represented by parabolic orbits, that is to say, by ellipses whose axes aie of infinite length: and the computations of their motions are almost always performed upon this hypothesis. Secondly t there is no limit t to the inclinations of <he planet of . their orbits to that of the ecliptic. Thirdly, there is no general coincidence in the direction of their motions from west to east, rather than from east to west, like what is observed among the planets. To determine the situation and dimensions of the e'lipsc ay povaW/fcj v,\:rJ:. shall represent the motion of any given comet, is a problem of pure geometry. For the solution of this problem, and for the determination of the elements of the orbit, three complete observations of the right ascension and declination of the comet, with the times at which they were made, are in general sufficient. The instruments indispensably necessary for making these observations, are, a sidereal clocks a qua- . drant, and a transit instrument. We believe there is neither a sidereal clock nor a transit instrument in the colony; but we are proud to be able to say, that there are gentlemen in the surveyor-general's office who could use those instruments with skill, nice as are the adjustments which some of them, particularly the transit instrument, require; arid we hope the time is not far distant when these and the other instruments of European observatories will be directed upon the brilliant skies of New Zealand. The geometrical problem, of which we have spoken in this paragraph was first solved by Newton, who calls it longe dijfficillimum ; but at present there is no aspirant to the astronomical chair in our universities, who is not, almost in the days of his boyhood, familiar with the details of the computations connected with it, and no better proof could be adduced of the wonderful, progress of the science of Astronomy in the course of a single century. The elements of the orbit, to be determined from the observations just men tioned, are, the perihelion distance, » place of the perihelion, the time of perihelion passage, the longitude o f node, and the inclination of the These five elements being found, t' of the comet is completely fixed, will always furnish the means o** ing it upon its reappearances. Some few comets have b tained to move in hyperbolas, course, when they pass the : can never more return wit" of our observation, but raus' systems, cr be lost in space. Far the greater move in .vliipses, anc form of their orbits if traction of the plan' as permanent memb In our next Bur succinct history of and of some int'with them.