158 



KNOWLEDGE. 



[July 2, 1900. 



ASTRONOMY WITHOUT A TELESCOPE. 



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

 VI.— THE MILKY WAY. 



The sliort nights of midsummer do not in general give 

 much opportunity to the Astronomer. But twice in 

 the year the most wonderful of all celestial objects 

 stretches itself across our English zenith and sweeps 

 downwards to either horizon. This is that 



" Broad and ample road whose dust is gold 



And pavement stars, as stars to thee appear. 



Seen in the Galaxy, that Milky Way. 



Which nightly as a circling zone thou seest 



Po^vdered with stars." 

 Its sweep at midnight in mid-July is from the north 

 eastern horizon where the constellation Auriga is just 

 rising, through Perseu.s and Cassiopeia on to Cygnus 

 in the zenith ; descending again on the other side 

 through Aquila. Serpens, Sagittarius and Scoi-jiio to 

 the horizon in the south-west. The second time when 

 it crosses the zenith is at midnight in mid-December, 

 when it sweeps upwards from the south-eastern horizon 

 in Argo, between Orion and Gemini to the zenith now 

 marked by the constellation Auriga; from whence it 

 passes downwards through Perseus and Cassiopeia to 

 the north-west horizon where the constellation Cvgnus 

 is setting. 



The Galaxy is no modern discovery. Ptolemy of 

 Alexandria has handed down to us a vei-y full and 

 precise description of it, and it has caught the attention 

 and stirred the imagination of races even as savage 

 as the Australian black fellows. It has been thought 

 of as the roadway of the Gods by which they passed 

 from their halls of eternal light, when they wished 

 to visit this nether world of oui-s ; or it is " Die -lakobs- 

 strasse, " the mystic ladder which the j^atriarch saw in 

 his dream at Bethel, up and down which the angels 

 moved. 



Ptolemy and the Greek Astronomers had recognized 

 two leading facts concerning it. One, that it marked 

 out a zone in the sky, the centre of which was neai'ly a 

 great circle; the other, that it was not equal and 

 regular everywhere but varied in different regions, in 

 breadth, in brightness in colour, in distinctness, and 

 especially that in some places it broke up into two 

 distinct streams. So much therefore was known about 

 it long before the invention of the telescope, ajid 

 though it gives to our greatest telescopes their most 

 gorgeous starfields, though in some portions it still 

 defies the efforts of our most powerful instniments 

 fully to resolve it, though its characteristic formations 

 are only brought out when we are dealing with stars 

 far fainter than can be individually detected by the un- 

 aided sight, yet the Milky Way as a whole is essentially 

 a naked eye object. 



The dwellers in cities and towns, smoke-veiled and 

 flaring with arc lamps or incandescent lights, must 

 abandon all hope of a really intimate knowledge with 

 the delicate structure of the Milky Way. But there are 

 many and many stations in this our island, — lone country 

 houses, little villages, — upon which stars of the short 

 dark summer night will shine down like silver points 

 set in ebony. The faint twilight, visible all night 

 long above the northern horizon, will not interfere 

 with tlie darkness of the zenith and the south. The 

 evasive moon recognizes that the season belongs of 

 right to her more powerful brother, and either does not 



show herself at all, or timidly skii-ts the south as if 

 anxious to escape notice. So though the summer hours 

 of darkness are so few, sufficient of them may be utilized 

 for so delicate a study as that of the Milky Way. 



The reason why it is so pre-eminently a naked eye 

 object is easily seen. The field even of a comet^seeker 

 or any other telescope of wide-field and low magnifying 

 power deals with .so inconsiderable a fraction of the 

 whole sky. It is impossible in the telescope to mark out 

 the boundaries of the Way; to see where it radiates 

 and divides ; where it reunites and condenses again. 

 It can only be examined piecemeal, a very small fraction 

 at a time — " the wood cannot be seen for the trees. ' 

 It is necessary, therefore, if we are to gain any 

 adequate knowledge of the structure of the Milky Way 

 as a whole, that we should supplement telescopic and 

 photographic examination by the most careful and 

 thorough scrutiny with the unassisted sight. 



This is astronomical work of a high order of import- 

 ance which has been very seldom adc(|uately attempted. 

 The names of Hcis, Boeddicker, Easton and of a very few 

 others, occur in this connection, and from the nature of 

 the case, the difficulties of the work being great, it is 

 most important that their observations should be con- 

 tinually repeated. 



It is not my intention in these papers, either to 

 describe what other observers have seen or to give any 

 regular history or summary of observations. That has 

 been done most excellently before. Nor do I wish to 



\'ia Lactea. Boroalis 1. ^cutuin-Cepheus. 



describe what an observer might be expected to see for 

 himself, since I fear in many cases the reader would 

 content himself with the description. My intention is 

 simply to give such merely general indications of the 

 work which may be attempted and the manner in which 

 it may be set about, that those who wish so to do may 



