KNOWLEDGE & SCIENTIFIC NEWS. 



[Feb., 1904. 



placed at the same distance, would be reduced to a star 

 of about 2-1 magnitudes, and as the photometric magni- 

 tude of 61 Cygni is about 5-1, we have a difference of 3 

 magnitudes in favour of the Sun. This makes the Sun 

 nearly 16 times brighter than fii Cygni, and would indi- 

 cate that it has about 60 times the mass of the star. The 

 spectrum of 61 Cygni is of the second or solar type, but 

 not exactly similar to that of the Sun. 



Some of the faint satellites to bright stars (mentioned 

 in my paper on "Stellar Satellites") must be either bodies 

 of small mass or slight luminosity. Take the case of 

 Burnham's 14th magnitude satellite to Aldebaran. As- 

 suming that its parallax is the same as that of Aldebaran, 

 or about one-tenth of a second, we have the Sun reduced 

 to a star of the 5th magnitude at the same distance. 

 This would make the Sun 9 magnitudes, or about 4000 

 times brighter than this faint star ! It must therefore be 

 either a comparatively small body, or else it must have 

 proceeded a long way on the road to the total extinction 

 of its light. If we suppose the density and surface 

 brilliancy to be similar, the ratio of the masses would be 

 about 25,000 to I, and this small star would be less than 

 14,000 miles in diameter. It seems highly improbable 

 that a body so much smaller than the planet Jupiter 

 should continue for long in the sun-like stage. More 

 probably it is a "cooled down sun." If its mass is not 

 miniature, its light is certainly small. 



The sun if placed at the distance of Regulus would 

 shine with about the same brilliancy as the 8i magnitude 

 satellite to that bright star. This satellite has close to it 

 a faint companion satellite of the 13th magnitude. As 

 both are moving through space with Regulus they are 

 evidently physically connected with the bright star and 

 lie at the same distance from the earth. This 13th 

 magnitude star is therefore 4^ magnitudes, or over 60 

 times fainter than the Sun. The accuracy of the small 

 parallax found for Regulus (o"-022) may perhaps be 

 doubted, but there can be no doubt, owing to the common 

 proper motion of all three stars, that Regulus and the 

 faint satellite are at practically the same distance from 

 the earth. The great difference in their light — nearly 12 

 magnitudes — indicates that Regulus is about 46,000 times 

 brighter than its faint attendant. There must therefore 

 be an enormous difference either in their size or the 

 luminosity of their surface. 



The measures of the double star « Urscc Majoris show 

 that it is a binary star. There is a difference of at least 

 9 magnitudes between the components, showing that 

 one is at least 4000 times brighter than the other. Con- 

 siderable difference in size or great discrepancy in surface 

 brightness is therefore absolutely certain. 



The bright star 7 Draconis (2^ magnitude) has a faint 

 companion of the 13th magnitude which seems to be 

 travelling with it through space. The difference of loi 

 magnitudes between the two implies that one is at least 

 10,000 times brighter than the other. Their disparity in 

 mass or inecpality in surface brightness must therefore 

 be enormous. 



Although calculation shows that the companions of 

 Sirius and Procyon are each equal to the Sun in mass, 

 still, as far as luminosity is concerned, they may be con- 

 sidered as miniature, or at least minor, suns. If the Sun 

 were placed at the distance of Sirius it would shine as 

 bright as the Pole Star, whereas the Sirian satellite is 

 only of the loth magnitude, or nearly 1300 times fainter 

 than the Sun. In the case of Procyon, the Sun placed 

 in the same position would l)eover 16,000 times brighter 

 than the faint attendant. These small stars are probably 

 "cooled down suns'' which are verging towards the total 

 extinction of their light. 



Another somewhat similar case is that of the binary 

 companion to the star 40 (o-) Eridani. This small binary 

 star is of the 9th magnitude, while the primary star is 

 about 4J. As both have a common proper motion 

 through space they are evidently physically connected, 

 and therefore lie at practically the same distance from 

 the earth. I'rofessor Asaph Hall found a parallax of 

 o"-22 for the brighter star. Assuming this parallax for 

 the binary pair, I find from Burnham's orbit a combined 

 mass equal to o'yi of the Sun's mass. Placed at the 

 same distance the Sun would shine as a star of 3-28 mag- 

 nitude, that is 572 magnitudes, or 194 times, brighter 

 than the binary, which therefore seems to be another 

 sun, or rather a pair of suns, on the road to extinction. 



The globular clusters, composed as they are of such 

 faint stars, suggest the inevitable conclusion that either 

 the components are miniature in size, or else that these 

 wonderful objects lie at a vast distance from the earth. 

 Even an approximate distance has not been found for 

 any of them. If we assume a parallax of Jjyth to jJinth of 

 a second — 163 to 326 years' journey for light — the com- 

 ponent stars of most of. them would be considerably 

 fainter than our Sun would be if placed at the same dis- 

 tance. On this assumption they would be relatively 

 small bodies. On the other hand, if we assume a parallax 

 of ,A,,th to i,'„„th of a second — from 1600 to 3200 years' 

 light journey — the Sun would be reduced to about the 

 I ^;\ to 15th magnitude, and this would make the compo- 

 nent stars equal to or brighter than the Sun. That each 

 of the stars which compose these clusters is e(iual to our 

 Sun in size and brightness seems improbable, and perhaps 

 the most likely supposition is that they are comparatively 

 small bodies, and are not so far from the earth as is 

 sometimes supposed. 



Ceylon 

 Pearl Oyster Fisheries. 



Professor Herdman's Report to 

 the Colonial Government. 



In 1801 the Island of Ceylon became definitively a liritish 

 possession, and with the removal of Dutch power there 

 passed into English hands the control and the proceeds 

 of the "pearl oyster" fisheries. Since the occupation 

 of the Island its pearl banks have, it is computed, brought 

 over one million pounds sterling into the treasury chest 

 of the Government. 



Although the aggregate amount derived from the 

 Ceylon fisheries is suggestive of a prosperous mainte- 

 nance of the native industry, in reality the situation has 

 long afforded ground for disturbing conclusions. In the 

 year 1S91 there was an extraordinarily abundant oyster 

 yield, the estimated revenue bemg placed at one million 

 rupees, whereas ensuing periods have demonstrated hut 

 a dismal tale of fishery failures. There was, however, 

 a good fishery last year (1903). Theories and specula- 

 tions have been put forth from time to time regarding 

 the phenomena of these strange oyster disappearances, 

 but comparatively little which might tend to throw real 

 light upon the question has resulted from the discussions. 



In such circumstances and mindful of the probable 

 recurrence of conditions likely to profoundly modify or 

 even jeopardise the pearl fishery, the Colonial Government 

 determined in 1900 to seek outside and expert aid with 

 the view of elucidating the scientific and economic 



