of the regular star-showers of August and November, and those of smaller interest and abundance in January, April, October, and December, with suitable maps and instructions to enable them to obtain, without unnecessary pains bestowed in preparations or expense, the most careful and complete records of their extraordinary displays. In order that the operations of the Committee may thus continue to be systematically directed towards the objects which have acquired important interest from the discovery of the astronomical connexion of shooting-stars with the orbits of comets, introducing the strictest methods of inquiry into the laws of their appearance, the Committee earnestly desire the renewal, in the coming year, of the support which, since its first formation, by their correspondence and cooperation, observers have hitherto freely contributed to the British Association.

Notices of the appearance of twenty-two fireballs and small bolides have during the past year been received by the Committee, fourteen of which were compared to the apparent size and brightness of the moon, and the latter include three detonating meteors of the largest class. Descriptions of some of the largest of these meteors are contained in the accompanying list and in the following paragraphs of the Report. No notice of the fall of an aërolite during the past year has been received, although the occurrences of large meteors during the months of autumn and spring, preceding April last, were more than ordinarily frequent. Of one of these, which appeared with unusual brilliancy in Cornwall, Devonshire, and the south-western counties of England on the evening of the 13th of February, it is possible to estimate, at least approximately, the locality and the real elevation of its flight. Careful observations of such phenomena when they appear are, however, again recommended by the Committee to all observers who may have the necessary astronomical skill, and the rare opportunity to note their brilliant courses by the stars.

In the discussion of some papers on Meteoric Astronomy which follow the foregoing observations, it will be seen that in the hands of its talented originator, Prof. Schiaparelli, the cosmical theory of periodical shooting-stars has received fresh and valuable illustrations, and the apparently inexplicable grouping of radiant-points for several successive days in the neighbourhood of a general centre of divergence, if not explained, appears to depend upon effects of planetary disturbances of a single meteoric stream from which the parasitic radiant-points have been derived. The discussion of such examples is simplified, and their complete explanation is, perhaps, not beyond the reach of the persevering application with which skilled astronomers in every country are now bent on the solution of the complicated and intricate geometrical problems presented to them by the distribution and features of the known radiant-points of shooting-stars. To a brief description of this interesting memoir are added, at the close of the Report, some notices of works which have recently appeared on the more general branches of meteoric science.

I. METEORS DOUBLY OBSERVED.

1. A Table of the real heights of sixteen shooting-stars doubly observed in England during the meteoric shower of August 1870, independently of the observations recorded at the Royal Observatory, Greenwich, was presented in the last volume of these Reports. A comparison of the observations made on that occasion at the Royal Observatory, Greenwich, with those recorded at the other stations, enables the real paths of thirteen meteors (ten of which are new to the former list), seen by Mr. Glaisher's staff of observers, to be satisfactorily determined; and the real heights and velocities of the

meteors thus identified, together with the particulars of the observatio from which they are concluded, are entered in the Table opposite.

The accompanying diagram (drawn on the same scale as that in the la Report) readily exhibits to the eye the actual heights at appearance and di appearance (or the heights of the centres of the visible paths of the metec Nos. 1, 4, 9) above the earth's surface. The last vertical line on the rig represents (as in the last Report) the average height at first appearance a that at disappearance of all the meteors regarded as identified in the prese list, of which the approximate heights of those points have been satisfactori ascertained. The resulting average heights are:—

At first appearance. At disappearanc
Of 16 meteors in the last Report.... 74-1 B. S. miles.
Of 10 meteors in the present list
Of 20 meteors observed in Aug. 1863 81.6

120

Fig. 1.

71.7

Reference numbers.

1 2 3 4 5 6 7 8 9 10 11 12 13

120

47.6

54.4

57.7

Heights at appearance and disappearance of thirteen shooting-stars simultaneously observed at the Royal Observatory, Greenwich, and at other stations in England, August 6th-11th, 1870. (Nos. 1, 4, 9 are calculated heights at the centres of the real paths.)

The present average heights are somewhat less than those observed in the year 1863; but they agree more closely with the general average height at first appearance, 70.05 miles, and that at disappearance, 54-22 miles (as given in the Report for 1863, footnote on p. 328), of nearly all the shooting-stars

B.) Birmingham; (H.) Hawkhurst, Kent; (L.) Regent's Park, , 1870.

simultaneously observed until the beginning of that year. The average velocity of the Perseïds, relatively to the earth, observed in the year 1863 was 344 miles per second, and that of the three Perseids satisfactorily well observed in the present list is 37 miles per second. In his original letters to Father Secchi on their connexion with Tuttle's comet (Comet III., 1862), now universally accepted as a true basis of their cosmical theory, Prof. Schiaparelli calculated, from the known elements of the comet's orbit, that the velocity with which the Perseïds enter the earth's atmosphere (allowing for a very minute influence of the earth's attraction) is 38 miles per second. That the direct determination of the velocities of the August shooting-stars which were made last year should, in this instance, so exactly agree with the value found by calculation (although from the small number of identifiable meteors the probable error of the determination is rather large), is, from the great scale and general excellence of the observations, at least provisionally, a successful confirmation of the astronomical theory of the August meteors, and a satisfactory conclusion from the simultaneous watch.

2. During the corresponding observations of the meteor-shower of November last, in which the observers of Mr. Glaisher's staff at the Royal Observatory, Greenwich, also took an important share, the coincidence of the times of appearance and of the other particulars of a single meteor only of the shower simultaneously observed at Greenwich and at Tooting, near London, could be established, the descriptions of which, as given by the observers at those stations, were as follows::

7

(8)

Cygni.

1 5 56 Greenwich... Length of path 15°. Observer, WM. MARRIOTT.

15 15

0 Tooting Meteor fairly well observed. Observer, H. W. JACKSON.

The apparent paths of the meteor among the constellations present a considerable parallax in the right direction of displacement, as seen from the two observers' stations, to lead to a positive determination of its real altitude above the earth. The concluded path of the meteor is nearly horizontal at a height of about fifteen miles above the earth's surface. The small distance (only seven miles) between the two stations, greatly increasing the effect of the errors most difficult to avoid in the observation and description of such transitory phenomena, must, however, for the present be regarded as precluding certainty from the conclusion, which would otherwise attach to this unusually low elevation of a meteor's real path.