There is no more interesting chapter in the history of astronomy than that relating to meteors. A hundred years ago shooting-stars were not considered to be astronomical phenomena. They were supposed to be merely inflammable vapours which caught fire in the upper regions of our atmosphere, although both Halley and the scientist Ernst Chladni (1756-1827) had notions of their celestial origin. For thirty-three years after the beginning of the century, however, nothing was heard of meteoric astronomy, nor was the subject considered as part of the astronomer’s labours.

A great meteoric shower took place on the night of November 12 and morning of November 13, 1833. The shower was probably the grandest ever witnessed, the shooting-stars being literally innumerable. The display was best observed in America, and was attentively watched by Denison Olmsted (1791-1859), Professor of Mathematics at Yale, and by the American physicist, A. C. Twining (1801-1884). These investigators discovered that all the meteors which fell during the great shower seemed to come from the same part of the celestial vault. In other words, their paths, when traced back, were found to converge to a point near the star ? Leonis. This observation gave the death-blow to the theory of their terrestrial origin. The point known as the “radiant” was clearly a point independent of the Earth. Olmsted also recognised the fact that the shower had taken place in the previous year, and he regarded it as produced by a swarm of particles moving round the Sun in a period of 182 days. Soon after this it was noticed that the phenomenon took place in 1834 and subsequent years with gradually decreasing intensity. It was then remembered that Humboldt had observed in November 1799 a very brilliant shower, and accordingly Olbers suggested that another shower might be seen in 1867.

The falling stars of August were next proved by Adolphe Quetelet (1791-1874) to form another meteoric system; and accordingly the theory of Olmsted that the November meteors moved round the Sun in 182 days had to be abandoned, for, says Miss Clerke, “If it would be a violation of probability to attribute to one such agglomeration a period of an exact year or sub-multiple of a year, it would be plainly absurd to suppose the movements of two or more regulated by such highly artificial conditions.” Accordingly Erman suggested in 1839 the theory that meteors revolved in closed rings, intersecting the terrestrial orbit; and that when the Earth crossed through the point of intersection, it met some members of the swarm. The subject now remained in abeyance for thirty-four years, if we except some wonderful ideas put forward in 1861 by Daniel Kirkwood (1813-1896), an American astronomer, who stated his belief in the disintegration of comets into meteors; but little attention was paid to his opinions. In 1864 the subject was taken up by Hubert Anson Newton (1830-1896), Professor at Yale, who undertook a search through ancient records for the thirty-three-year period of the Leonids or November meteors. His search was highly successful, and having demonstrated the existence of the period, Newton set himself to determine the orbit. He indicated five possible orbits for the swarm, ranging from 33 years to 354½ days. Newton was unable to solve the question mathematically; but here Adams, the discoverer of Neptune, came to the rescue, and demonstrated that the period of 33¼ years was alone possible, and that the others were untenable. These investigations, completed in March 1867, proved the existence of a great meteoric orbit extending to the orbit of Uranus.

Meanwhile Newton had predicted a meteoric shower on the evening of November 13 and morning of November 14, 1866. His prediction was fulfilled. The shower was inferior to that of 1833, but was still a magnificent spectacle. Sir Robert Ball, then employed at Lord Rosse’s Observatory, observed the shower, and records the impossibility of counting the meteors. This great shower attracted the attention of astronomers all over the world to the study of meteors. Meanwhile Schiaparelli had been working at the subject for some time, and in four letters addressed to Secchi, towards the end of 1866, he showed that meteors were members of the Solar System, possessed of a greater velocity than that of the Earth, and travelling in orbits resembling those of comets, in the fact that they moved in no particular plane, and that their motion was both direct and retrograde. Schiaparelli computed the orbit of the Perseids or August meteors, and was astonished to find it identical with the comet of August 1862. This was a proof of the connection between these two apparently widely different types of celestial bodies. Early in 1867 Schiaparelli found that Le Verrier’s elements for the orbit of the Leonids were identical with those of the comet of 1866, discovered by Ernst Tempel (1821-1889). Peters of Altona had meanwhile reached the same conclusion; while Edmund Weiss (born 1837) of Vienna pointed out the similarity of the orbit of a star-shower on April 20 and that of the comet of 1861. He also drew attention, independently of Galle and D’Arrest, to the close connection between the orbits of the lost Biela’s comet and the Andromedid meteors of November.

All doubt as to the connection of comets and meteors was removed by the great shower on November 27, 1872. Biela’s lost comet was due at perihelion in 1872, and although searched for was not observed; but when the Earth crossed its orbit, a great meteoric shower took place. “It became evident,” says Miss Clerke, “that Biela’s comet was shedding over us the pulverised products of its disintegration.” The shower was little inferior to that of 1866. Meanwhile Ernst Klinkerfues (1827-1884), Professor at GÖttingen, believing that Biela’s comet itself had encountered the Earth, telegraphed to Norman Robert Pogson (1829-1891), Government astronomer at Madras, to search for the comet in the opposite region of the sky. Pogson did observe a comet, but certainly not Biela’s, although probably another fragment of the missing body.

The theory of the actual disintegration of comets was enunciated by Schiaparelli in 1873, and developed in his work ‘Le Stelle Cadenti.’ He was led to regard comets as cosmical clouds formed in space by “the local concentration of celestial matter.” He then remarks that a cosmical cloud seldom penetrates to the interior of the Solar System, “unless it has been transformed into a parabolic current,” which may occupy years, or centuries, in passing its perihelion, “forming in space a river, whose transverse dimensions are very small with respect to its length: of such currents, those which are encountered by the earth in its annual motion are rendered visible to us under the form of showers of meteors diverging from a certain radiant.”

Schiaparelli next pointed out that when the current of meteors encounters a planet, the resulting perturbations cause some of the meteoric bodies to move in separate orbits, forming the bolides and aerolites which fall from the sky at intervals. “The term falling stars” he says, “expresses simply and precisely the truth respecting them. These bodies have the same relation to comets that the small planets between Mars and Jupiter have to the larger planets.” In the third chapter of his ‘Le Stelle Cadenti’ he explicitly states that “the meteoric currents are the products of the dissolution of comets, and consist of minute particles which certain comets have abandoned along their orbits, by reason of the disintegrating force which the Sun and planets exert on the rare materials of which they are composed.”

In 1878 Alexander Stewart Herschel (born 1836), son of Sir John Herschel, and a famous meteoric observer, published a list of known or suspected coincidences of meteoric and cometary orbits, amounting to seventy-six. Meanwhile much progress has since been made in the observation of meteoric showers and the determination of their radiant points. In this branch of astronomy, by far the greatest name is that of William Frederick Denning, the self-made English astronomer. Born at Redpost, in Somerset, in 1848, his career of meteoric observation commenced in 1866. For the past forty years he has attentively devoted himself to the observation of meteors. From 1872 to 1903 he determined the radiant points of no fewer than 1179 meteoric showers. In addition to this, he published, in 1899, a catalogue of meteoric radiants, containing 4367; and he has carefully studied the remarkable objects known as fireballs or “sporadic meteors.” He has occasionally been able to trace a connection between fireballs and weak meteoric showers, but he concludes that they “must either be merely single sporadic bodies, or else the survivors of some meteor group, nearly exhausted by the waste of its material during many past ages.” All of Denning’s meteoric work has been done in his spare time, for it must be borne in mind that he pursues the profession of accountant in Bristol, and that only his leisure hours have been devoted to the science of astronomy. His researches have been entirely conducted with the unaided eye. His only instrument is a perfectly straight wand, which he uses as a help and corrective to the eye in ascribing the paths of the meteors. Thanks to the laborious work of this able English astronomer, the observation of meteors is now a scientific branch of astronomy. In the words of Maunder, “for six thousand years men stared at meteors and learned nothing, for sixty years they have studied them and learned much, and half of what we know has been taught us in half that time by the efforts of a single observer.”