190 



KNOWLEDGE. 



[August 1, 1898. 



during the eighteen month3 preceding June. The latter 

 month, however, furnished a record, for three new comets 

 were discovered, while two known comets were redetected. 

 It will be found on searching through catalogues of comets 

 that no other month has ever yielded such an abundant 

 harvest of important observations in this branch of astro- 

 nomy. This is the more remarkable from the circumstance 

 that June, with its strong twilight, is unfavourable to the 

 detection of comets. The summary of recent discoveries 

 may be stated as follows ; — 



No. 2 is a reobservation of Encke's periodical comet, 

 No. 4 of Wolf's comet. These, with Perrine's comet found 

 on March 19th, represent a total of six comets visible, 

 though they cannot all be seen on the northern hemi- 

 sphere. Encke's and Coddington's comets have a southern 

 declination of about forty-five degrees early in August. 

 The latter is the second comet discovered accidentally on 

 a photographic plate, the previous instance being that of 

 1892 v., which was similarly detected by Mr. Barnard. 

 There can be no doubt that astronomical photography, 

 when it comes to be more extensively practised, will afford 

 the means of revealing many new comets. 



Dr. Schorr has pointed out that the elements of Perrine's 

 comet of June 14th exhibit a remarkable similarity of 

 elements with those computed for Pons's comet of 1812 

 and 1884. 



The following are ephemerides of three of the comets 

 now visible : — 



Comet Wolf. 



The distance from the earth varies very little from two 

 hundred and seventy millions of miles during the month. 



Comet Perrine (June 14th). 



At the middle of August this comet will be only about 

 twenty-three degrees west of the sun, so the conditions 

 affecting its visibility will be very unfavourable. It is 

 moving rapidly .southwards and will soon be lost to 

 observers in our latitude. 



In addition to the various comets mentioned, astronomers 

 are expecting the return of Tempel's comet (1867 II.), but 

 its detection has not yet been announced ; and, in view 

 of the fact that its distance is increasing, and that it 

 escaped observation at the last three returns, there seems 

 but a slender prospect that it wiU be observed during the 

 present year. 



A uffust Metrors. — With the return of the Pereeids, meteoric 

 observers have plenty of attractive work in hand. Meteors 

 are abundant, and the season is a convenient one for night 

 work of this kind. This year the moon will be full on the 

 morning of August 2nd, so that in the early part of the 

 month the sky will be very light, and only the larger 

 Perseids are likely to be observed. Moonlight will, in fact, 

 prove rather a serious hindrance to observation during 

 the first eight or nine nights, for our satellite moves so 

 rapidly northwards that she rises very little later on 

 successive evenings. Her age and times of rising, at the 

 most important period, are as follows : — 



Age at noon. Time of riuing. 



The last quarter occurs on the evening of the 9th, so 

 that on the night of the 10th, when the maximum of the 

 shower is usually attained, the light of the moon will have 

 declined so much as to be comparatively feeble. In the 

 last number an ephemeris was given of the Perseid radiant 

 to the end of July, and the following is a continuation of it 

 to August iHth, when the display will be nearly exhausted: — 



It will be interesting to test the accuracy of this 

 ephemeris by careful observations made on the individual 

 nights mentioned. Notwithstanding the interference of 

 the moon the Perseids are usually so active, even at the 

 early part of August, that the radiant point may be readily 

 derived. 



Bright Meteors. — On 'June oth, about lOh., a meteor 

 brighter than Vega travelled from /3 Ophiuchi to p Lyra?. 

 It was bluish white in colour, and left a trail of sparks. 

 Observer : Mr. Albert Ashby, West Croydon. 



On June 2Cth, llh. 24:|m., a meteor, about as bright as 

 a first magnitude star, appeared in a barren part of the 

 sky, eight degrees north of the star cr Sagittarii. It pursued 

 an upward course, vanishing exactly one degree west of 

 9 Serpentis, and during its flight increased so much in 

 brilliancy that at the end it was equal to Venus at her 

 best. The meteor was bluish white in colour, and moved 

 slowly along its path in about five seconds. Observer : 

 Kev. S. J. Johnson, Bridport, Dorset. 



