214 



KNOWLEDGE 



[September, 1903. 



at the time of full moon on July 9 it continued visible to the 

 naked eye, and seemed decidedly brighter, on the whole, than Perrine's 

 comet of September and October, 1903. On July 19, as viewed in a 

 field-glass, the comet had a tail about 2 degrees long, directed 

 southwards, but it was ditlicult to assign exact limits owing to the 

 faintness of tlie outer portions. It ia rarely that the apparent paths 

 of comets are placed so favourably in the sky for observational 

 purposes as were those of Perrine and Borrelly, for the great majority 

 of these visitors in their flights to and from tlie sun are not far above 

 the horizon, and more or less involved in twilight and obscuring 

 vapours. The Uvo bodies alluded to passed, however, near the zenith, 

 and being visible to the unaided eye could be readily followed through 

 extensive ranges of the firmament. But it is to be remarked that 

 while Perrine's comet of 1902 attracted a large amount of attention, 

 the present object, though equally deserving, received comparatively 

 little notice. In the case of the former, however, special comments 

 were made in the newspapers soon after its discovery, and the 

 probabilities of its developing into a comet of the largest class were 

 exaggerated. Needless to say, the public expected much and saw 

 practically nothing. Thus the present visitor has failed to excite 

 much enthusiasm, for a good many people, having looked in vain for 

 certain previous comets as well as for November meteors, are inclined 

 to regard promised celestial apparitions as rather mythical in view of 

 several past disappointing experiences. 



Borrelly's comet has been very fully investigated at the Lick 

 Observatory (Bulletin 47). Besides the observations for position, the 

 spectrum has been carefully studied, and several photographs, both 

 of the comet and its spectrum, have been secured. The spectrum 

 consisted of the chai'acteristic cometary bands, due to carbon or some 

 of its compounds, and it may be worth while to mention that the 

 three bands in the visible spectrum were easily seen by Mr. Fowler 

 and others with a small slit spectroscope attached to a 3-inch refi'actor. 

 Photographs taken before July 14th show two tails, one long, straight, 

 and narrow, and the other of about one-third the length, and greatly 

 curved, the latter being the brighter. On the last two days of June 

 the longer tail was split into two branches, but on the day following 

 it was again sharp and single. On July 14tli the straight tail, 

 extending over SJ degrees, alone appears, widening out slightly as it 

 extends away from the head. Throughout the period of observation, 

 the straight tail was directed almost exactly away from the sun, and 

 the nucleus was always sharply defined. 



Periodical Comets. — Though seven of these interesting objects 

 are due to return to perihelion this year, not one of them has been 

 detected at the time of writing. The following is the complete list of 

 the expected reappearances : — 



Probable Date 

 Comet. of Perihelion. Period of 



1903. Eevolution. 



Tempel-Swift ... January ... 5"547 years. 

 Brooks (1886 IV.)... March 25 ... 5-595 „ 

 Perrine (1896 VII.) April 27 ... 6441 „ 



Faye June 3 ... 7-488 „ 



Giacobini (1896 V.) June 22 ... 6 647 „ 

 Spitaler(189lII.)... August 1 ... 6378 „ 

 Brooks (1889 V.) ... December 11 ... 7-097 „ 

 The failure to re-observe these objects is doubtless to be attributed in 

 several cases to their unfavourable positions, but the number of large 

 telescopes more or less employed in cometary work would lead us to 

 expect more successes in this field. It should be remembered, however, 

 that these comets are not only small, but that they are subject to 

 physical changes inducmg great variation in their luminosity. 

 Holmes's comet was perceptible to the naked eye in 1892, but at its 

 next return was visibly reduced to the 15th magnitude, and could 

 only be distinguished in two telescopes, viz., the Yerkes 40-inch and 

 the Lick 36-inch refractor. It is probable tliat some of these 

 periodical comets are undergoing a process of disintegration similar 

 to that which affected Biela's comet, and that in time many of them 

 will lose their distinctive characters as cometary bodies, and be 

 resolved into distended meteoric streams, only visible from our planet 

 under the form of shooting stars. The two short-period comets of 

 D' Arrest and Pons-Winnecke are due in January, 1904, but the 

 circumstances attending their return are not favourable, and they are 

 both likely to escape observation. 



July Meieoes. — The weather during the latter part of July was 

 very unsettled, with much rain and cloud, so that few meteoric 

 observations could be obtained. The writer, at Bristol, watched on 

 July 24 for If hours, and saw 20 meteors, while on July 26 a 

 2 hours' watch yielded 20 meteors. The oncoming of tlie great 

 Perseid shower was distinctly evident on July 24, though only three 

 of its meteors were seen. Two of these were pretty bright, and 

 appeared within 2 minutes of each other at llh. 27m. and llh. 29m. 

 It is often the case that a pair of meteors from one and the same 



system make their apparitions within a short interval of time, and 

 the inference is that the two bodies formed portions of what was 

 originally one mass. Large individual meteors are probably often 

 broken up by disturbances affecting them during their revolutions, 

 and may be resolved into a number of small meteors moving in 

 nearly concentric orbits. The writer has occasionally recorded, 

 within a few seconds of each other, three meteors from a railiant 

 which has given no further manifestation of activity during a watch of 

 several hours' duration. On July 2'> two or three small Perscids 

 were seen, but the shower had apparently gained no strength since 

 July 24. The principal radiant seemed to be near B Pegasi at 

 348° -I 25°. No Aquarids were observed. The most remarkable meteor 

 recorded on the two nights appeared on July 26 at 12h. 45m. It 

 moved with extreme slowness from 64° -t- 27° to 16° + 14° in about 

 31 seconds, and came almost to a standstill at the end of its path. 

 It had a dull reddish nucleus, and was directed from a radiant a long 

 way back on its line of flight at 233° -H 38° near !| Corona;. The same 

 meteor was well observed by Prof. A. S. Herschel at Slough, who gives 

 the path as 291° -H 31° to 3I0i''-l-22°, and by Mr. A. King at Leicester, 

 who recorded it as 315° — 13° to 323i° — 191°. Prof. Herschel describeg 

 the colour as yellow, then reddish-orange, and estimated the duration 

 of flight as Zi to 4 seconds. Mr. King says the tint was deep orange, 

 and duration 2i seconds. The meteor passed over the northern 

 district of Hampshire, and fell from a height of 51 to 39 miles, along 

 a path of 21 miles, witli a velocity of 6A miles per second. Atmospheric 

 resistance had probably much reduced its original speed, and could 

 the luminous career of the meteor have been prolonged until much 

 nearer the earth's surface, a further " slowing up " would have 

 become obvious. 



A bright meteor, belonging to the a Andromedids of July, was 

 observed by Prof. Herschel at Slough, and by the writer at Bristol, 

 on July 26, 12h. 35m. It was seen nearly in the zenith of Slough, 

 and here it appeared as bright as Sirius. The radiant was at l°-f-27°, 

 and height 66 to 46 miles, from Han-ow to High Wycombe. Length 

 of path 29 miles, and velocity 53 miles per second. 



Large Meteors. — On July 1, at about lOh. 25m., a meteor 

 brighter than Venus was seen by Mr. T. H. Astbury, of Wallingford, 

 Berks, passing from 318° -1-321° to 328° -h 26'. It left a white streak, 

 enduring several seconds. 



On July 30th, llh. 40m., a magnificent meteor, "the size of a man's 

 fist," was observed near Bishop's Stortford, high in the S.S.W., and 

 passing towards S. It left a long train, and illuminated the landscape 

 vividly. At Seaton, East Devon, the same meteor was seen in the 

 N.E , and gave a brilliant flash. It travelled in a S.E. direction, and 

 left a long trail of fire. It was also observed at Yarnseombe by 

 several people, who were startled at the sudden outburst of light, and 

 at first mistook it for lightning. 



THE FACE OF THE SKY FOR SEPTEMBER. 



By W. Shackleton, f.r.a.s. 



The Sun. — On the 1st the sun rises at .5. 12 and sets at 

 6.48 ; on the 30th he rises at 5.58 and sets at 5.-42. 



The equation of time is negligible on the 2nd ; this date, 

 therefore, is suitable for the ready adjustment of sun- 

 dials, etc. 



The Zodiacal Light is prominent in the east, just before 

 sunrise. 



Autumn commences on the 24th, when the sun enters 

 the sign of Libra at (J a.m. 



There is a total eclipse of the sun on the 21st, but only 

 visible from the Antarctic area (see Knowledge, p. 121, 

 vol. XXIV., 1901). 



Sunspots and faculiE have been prevalent of late ; at 

 the time of -writing there are three groups of spots on the 

 solar disc. 



The Moon : — 



The moon is in apogee on the 3rd and 30th, and in 

 perigee on the 19th. 



