The instrumental equipment of that observatory was somewhat antiquated, his largest telescope being a small refractor of 73 lines aperture, but he selected a line of work to suit the instruments at his disposal, observing nebulae and variable stars and keeping a watch on comets and new planets.
1.1 Comets 1.2 Planets
We may at once put the comets out of view.
We do not know whether the comets are really indigenous to the solar system or whether they may not be merely imported into the system from the depths of space.
Even if the comets be indigenous to the system, they may, as many suppose, be merely ejections from the sun.
In any case the orbits of comets are exposed to such tremendous perturbations from the planets that it is unsafe from the present orbit of a comet to conjecture what that orbit may have been in remote antiquity.
By this means she detected in 1783 three remarkable nebulae, and during the eleven years 1786-1797 eight comets, five of them with unquestioned priority.
The investigation of this substance and its properties (see Radioactivity) has proceeded so far as to render it probable that the theory of the unalterability of elements, and also the hitherto accepted explanations of various celestial phenomena - the source of solar energy and the appearances of the tails of comets - may require recasting.
The Memoirs of the Berlin Academy from 1761 to 1784 contain many of his papers, which treat of such subjects as resistance of fluids, magnetism, comets, probabilities, the problem of three bodies, meteorology, &c. In the Acta Helvetica (1752-1760) and in the Nova acta erudita (1763-1769) several of his contributions appear.
In Bode's Jahrbuch (1776-1780) he discusses nutation, aberration of light, Saturn's rings and comets; in the Nova acta Helvetica (1787) he has a long paper "Sur le son des corps elastiques," in Bernoulli and Hindenburg's Magazin (1787-1788) he treats of the roots of equation and of parallel lines; and in Hindenburg's Archiv (1798-1799) he writes on optics and perspective.
In the re- establishment of the field comets and in other directions a return was made to the republican forms of administration, and on the education question an agreement satisfactory to both the British and Dutch-speaking communities was reached.
The meteors, whatever their dimensions, must have motions around the sun in obedience to the law of gravitation in the same manner as planets and comets - that is, in conic sections of which the sun is always at one focus.
The great variety in the apparent motions of meteors proves that they are not directed from the plane of the ecliptic; hence their orbits are not like the orbits of planets and short-period comets, which are little inclined, but like the orbits of parabolic comets, which often have great inclinations.
Apart from the instances alluded to there seem few coincidences between the orbital elements of comets and meteors.
But there are really few comets which pass sufficiently near the earth to give rise to a meteoric shower.
Of 80 comets seen during the 20 years ending 1893, Professor Herschel found that only two, viz.
In the same year he published his essay on comets, Conamen Novi Systematis Cometarum, which was occasioned by the appearance of the comet of 1680.
A fourth class of bodies, the constitution of which is still in some doubt, comprises comets and meteors.
These differ in that comets are visible either in a telescope or to the naked eye, and seem to be either wholly or partially of a nebulous or gaseous character, while meteors are, individually at least, invisible to us except as they become incandescent by striking the atmosphere of the earth.
He intended to follow it up with similar treatises on Mars, Jupiter, sun, moon, comets and meteors, stars, and nebulae, and had in fact commenced a monograph on Mars, when the failure of a New Zealand bank deprived him of an independence which would have enabled him to carry out his scheme without anxiety as to its commercial success or failure.
He paid special attention to comets, and that of 1815 (period seventy-four years) bears his name in commemoration of its detection by him.
Of his Leichteste Methode, and his unique collection of works relating to comets now forms part of the Pulkowa library.
His observations on the three comets of 1618 were published in De Cometis, contemporaneously with De Harmonice Mundi (Augsburg, 1619), of which the first lineaments had been traced twenty years previously at Gratz.
The following is a list (compiled in 1909) of comets which are well established as periodic, through having been observed at List of Periodic Comets observed at more than one Return.
In addition to what has already been said formal assemblies convened by a magistrate; but while, in the of several comets in this list the following remarks may be made.
The perturbations of the comets discovered, the one by H.
But, as has been remarked by Dr Robert Grant (History of Physical Astronomy, p. 515), we are no more warranted in drawing so important a conclusion from casual remarks, however sagacious, than we should be justified in stating that Seneca was in possession of the discoveries of Newton because he predicted that comets would one day be found to revolve in periodic orbits.
English translations of the following portions of his works have appeared: - Treatise on Comets, by C. Gold, C.B.
In 1809 he published at Hamburg his Theoria motus corporum coelestium, a work which gave a powerful impulse to the true methods of astronomical observation; and his astronomical workings, observations, calculations of orbits of planets and comets, &c., are very numerous and valuable.
Between 1801 and 1827 Pons discovered thirty-seven comets, one of which (observed on the 26th of November 1818) was named after J.
1739, in 4to); Methodus inveniendi lineas curvas, maximi minimive proprietate gaudentes (Lausanne, 1744, in 4to); Theoria motuum planetarum et cometarum (Berlin, 1744, in 4to); Beantwortung, &c., or Answers to Different Questions respecting Comets (ibid., 1744, in 8vo); Neue Grundsatze, &c., or New Principles of Artillery, translated from the English of Benjamin Robins, with notes and illustrations (ibid., 1745, in 8vo); Opuscula varii argumenti (ibid., 1746-1751, in 3 vols.
During the ten years 1854-1864 Donati discovered six comets, one of which, first seen on the 2nd of June 1858, bears his name (see Comet).
In 1862 he published a memoir, Intorno alle strie degli spettri stellari, which indicated the feasibility of a physical classification of the stars; and on the 5th of August 1864 discovered the gaseous composition of comets by submitting to prismatic analysis the light of one then visible.
In autumn last I spent two months in calculations to no purpose for want of a good method, which made me afterwards return to the first book, and enlarge it with divers propositions, some relating to comets, others to other things, found out last winter.
Sir, I must now again beg you, not to let your resentments run so high, as to deprive us of your third book, wherein the application of your mathematical doctrine to the theory of comets and several curious experiments, which, as I guess by what you write, ought to compose it, will undoubtedly render it acceptable to those, who will call themselves Philosophers without Mathematics, which are much the greater number.
They are also revealed by the spectroscope in stars, comets and the sun.