August 1, 1900.] 



KNOWLEDGE. 



176 



to give the two extremities of the path at a glance aud 

 to remember them faithfully until he can in some way 

 or other not* them down. 



For this he will require a certain amount of what 

 we may term apparatus, either a celestial globe or a set 

 of star charts. The choice of the latter is of importance, 

 as no possible chart can show the entire sky without 

 grave distortion some way or other, and more important 

 for the present purpose there is only one projection 

 which will give a straight line on the chart for all great 

 circles or parts of them ; that is to say, for all lines 

 which impress us as straight lines as we see them on 

 the sky. 



The observer's first duty, therefore, is to acquaint 

 himself with the constellations ; his next, by repeated 

 and persistent efifort, to leai'n quickness and correctness 

 in fixing the extreme points of the meteor paths. This 

 done, he will recognise that there are several other 

 features in which meteors appear to differ, the one from 

 the other. His observations of the paths will soon show 

 him that the length of a meteor path varies greatly; 

 he cannot fail further to notice that the apparent speed 

 with which it travels varies also. To the record of the 

 path, therefore, should be added the determination of 

 its length, which of course can be read off from the globe 

 after the track has been marked down upon it, and the 

 time which the meteor took to traverse it. And as for 

 comparison with the records of other observers it is 

 essential to know when the meteor was seen, this 

 should also be noted as well as the duration. Indeed, 

 as a matter of order, the date and time of the occurrence 

 should come first ; then the position of the beginning 

 of the path; third, the position of the end; fourth and 

 fifth, the length of the path and the time which the 

 meteor took to traverse it. 



The actual meteors themselves also have their in- 

 dividual characteristics. Some leave phosphorescent 

 streaks behind them, others trains of sparks. More 

 striking than anything else is the enormous difference 

 in brightness, from one like the meteor alluded to above 

 " larger than the full moon at rising," down to others 

 only just visible to the naked eye. These particulars 

 as to character and brightness will be the sixth and 

 seventh items to note, and when a number have been 

 observed sufficient to give an indication of the radiant, 

 this should be added as an eighth. 



Steady persistent practice in noting these particulars 

 will soon give the obsei-ver increased skill. One item 

 requires especial attention — the duration of the meteor. 

 Mr. Denning tells us that he has trained himself by 

 obsei-%'ing the flight of arrows. He has employed a 

 friend to shoot these to distances from fifty to two 

 hundred yards at right angles to the line of sight, the 

 elevation being varied as much as possible, and that by 

 repeating these experiments he has learned to judge 

 intervals of from one to five seconds with an average 

 error of less than one-fifth second. 



All the above particulars and not merely the direction 

 of the paths alone are of value in the determination 

 of the radiant point. The meteors of one radiant have 

 similar characters as to colour, streaks, etc., and also 

 as to speed of course. The apparent length of path is 

 affected by the height of the radiant point, Mr. Denning 

 noting of the Perseids of August 10 that, whilst between 

 9 and 10 o'clock in the evening the brighter meteors 

 average a course of about 30°, in the morning hours 

 when the radiant is near the meridian their paths are 

 only one-third the length. 



As in all good -work, skill is not acquired at once, 



and the would-be meteor observer will find that he 

 makes many failures to begin with. His first successes 

 will probably be with some bright slow-moving meteor, 

 aud as these arc relatively few, he will probably have 

 to wait a very considerable time before he can accom- 

 plish much. This need of patience and practice is one 

 great reason no doubt why so few take up a pursuit 

 which requires no equipment and which soon becomes 

 full of fascination. Another is to be found in the 

 uiifortuiiatc fact that from midnight to dawn is a much 

 more fruitful time than from sunset to midnight, since 

 the meteors which come to meet the earth are necessarily 

 much more numerous than those that overtake it, and 

 the earth has its sunrise point in front as it moves 

 forward in its orbit, its sunset point behind. 



Yet there are always prizes to be secured. There is 

 a great pleasure when some brilliant wanderer flashes 

 by in knowing that one has secured as full and accurate 

 a record as possible of its appearance. It was seen but 

 for a moment, 



" Like a snowllake on the river. 

 One moment white, then gone for ever." 



Yet it has left something behind, something permanent, 

 something which years after may bo eloquent of un- 

 suspected truth. 



The great Perseid shower, chief of all those which 

 are of regular annual recurrence, has been rich in such 

 indication. It has shown itself to bo in intimate con- 

 nection with the Third Comet of 1862 discovered by 

 Swift. It has been traced night after night for a very 

 cousiderable time before the date of its maximum, 

 August 10, the radiant point travelling steadily back- 

 ward in the sky from the borders of Cassiopeia and 

 Andromeda in the middle of July to those of Camelo- 

 pardus in the middle of August; the steady shift of the 

 radiant, night after night, having been abundantly 

 demonstrated by observations as well as being in strict 

 accordance with theory. 



In sharp contrast with the shifting of the Perseid 

 radiant has been another fact which long years of patient 

 woi-k has enabled Mr. Denning to demonstrate — namely, 

 the existence of radiants which do not shift, radiants 

 which endure for many months together. Here was a 

 circumstance which could not have been anticipated, 

 which was indeed in flagrant contradiction to the theory 

 of meteoric motion, and which even yet remains without 

 any adequate explanation. Yet one single observer, 

 by sheer patience and perseverance, has driven home 

 the unexpected, unexplained, seemingly impossible fact, 

 and after having been long rejected even by cxpei-ts, 

 the fact of stationary radiants has at length received 

 general recognition. 



Such a fact, unexampled in the history of astronomy, 

 ought to make many a meteor hunter. For six thousand 

 years men stared at meteors and learnt nothing, for 

 sixty yeai-s they have studied them and learnt much, 

 and half of what we know has been taught us in half 

 that time by the efforts of a single observer. 



[The illustration on page 158 (.Tulj) should have been lettered 

 '' The Milky Way in CygnuB ; from M. C. Easton's ' La Voie Lac-tee.'"] 



THE TOTAL SOLAR ECLIPSE OF 1900, MAY 28 



(Second Pcqjer.) 

 By E. Walter Maunder, f.r.a.s. 



The Eclipse of 1900 has been so very prolific of result 

 that, even at this early date, to adequately notice every- 

 thing that has come to hand would require a long series 



