February 1, 1897.] 



KNOWLEDGE 



39 



inconceivable tenuity of the solar surroundings. Like 

 other similarly related comets, they probably are fragments 

 of a single disrupted mass. The intimate connection of 

 comets and meteors was indicated by Schiaparelli in 1866 

 on the ground of orbital identities, and was illustrated by 

 the reappearance of the vanished Biela under the guise of 

 a star-drift. The electrical nature of cometary illumination 

 has been confirmed by varied evidence. Bredichin's hypo- 

 thesis of the three types of comets' tails has proved a 

 useful aid to research ; and the presence of hydro-carbon 

 bands in their spectra, first recognized by Dr. Huggins in 

 Winnecke's comet of 1868, has turned out to be all but 

 unfailing. Finally, there is no longer reason to doubt that 

 the undisturbed motion of these strange bodies is approxi- 

 mately parabolic, and that the periodicity of some among 

 them has resulted from " capture " by the great planets. 

 Celestial sensations have not been wanting. The Vic- 



A Form of Equatoeial common in 1837. 



torian age has witnessed the outburst of no less than seven 

 new stars. T Coronse, the first spectroscopically examined, 

 showed itself to Dr. Huggins, May 16th, 18GG, as wrapt 

 in a mantle of blazing hydrogen ; and its condition was 

 typical, though not inevitable. The changes in quality of 

 the fading light of such objects are significant and curious. 

 Thus, Nova Cygni in 1876, Nova Aurigie in 1892, and 

 Nova Normif in 1893, displayed, to begin with, spectra of 

 the chromospheric type, which gradually assumed nebular 

 affinities. 



All that is known about the distances of the stars has 

 been learned since the Queen's accession. Near the close 

 of 1839, Bessel announced a genuine parallax for 61 

 Cygni ; two months later, Henderson communicated his 

 detection of a larger one for a. Centauri. This splendid 

 southern binary has not, so far, been superseded as the 

 sun's nearest neighbour ; yet its light spends four years 

 and four months in traversing the intervening twenty-five 



billions of miles. Sirius and Procyon are about twice as 

 distant ; two or three insignificant, swiftly moving objects 

 are of intermediate remoteness. On the whole, about 

 seventy stars are ticketed with nominal parallaxes, of 

 which, perhaps, half may be depended upon as real. Those 

 measured with the heliometer by Drs. Gill and Elkin are 

 of high authority ; but henceforward the photographic 

 method introduced by the late Prof. Pritchard will doubt- 

 less be extensively employed. 



The immense enlargement in the power and scope of 

 astronomical research effected during the last few decades 

 was strikingly illustrated 

 by Sir George Airy's ad- 

 ministrationat Greenwich. 

 His deliberate policy was 

 to keep the Koyal Observa- 

 tory true to its ancient 

 purposes, nor has it ever 

 departed from them. Yet, 

 born successor of Flam- 

 steed though he was, his 

 mind was open to con- 

 viction ; and he created, 

 within a stone's throw of 

 the spot where Flamsteed 

 had set up his iron sex- 

 tant, a magnetic, a photo- 

 graphic, and a spectro- 

 scopic department. The 

 sister establishment in the southern hemisphere, by the 

 activity of which England's universal dominion over 

 the seas is extended to the skies, is about to follow suit. 

 In a year or two, through the generosity of Mr. McClean, 

 a great astrophysical apparatus will be erected at the Cape, 

 and Imperialism will triumph in the New Astronomy. 



Peof. J. C. Adams, 



THE POLAR BEARS AT THE "ZOO." 



By F. E. Beddard, F.K.S. 



THE Polar bear is a beast which — contrary to what 

 might be supposed — does well at the Zoological 

 Society's Gardens. During recent years there has 

 been a continuous supply of the creature, and one 

 individual lately nearly topped the record of lon- 

 gevity in the menagerie by surviving for no less a period 

 than thirty-seven years. Instances of this kind— and 

 many might be cited from the collection in the Kegent's 

 Park — show how independent in certain cases are animals 

 upon their surroundings, and how futile were some of the 

 earlier attempts to explain the geographical range of 

 species by supposed necessities of climate and other inani- 

 mate surroundings. The Polar bears at the " Zoo " thrive 

 in the absence of sea-water and of ice, as may indeed be 

 seen at once fi'om our engraving, which represents the 

 active couple of bears now on view. To the ordinary 

 visitor to the Zoological Gardens the Polar bear is chiefly 

 attractive— at least in the case of the two young bears 

 now there — on account of its frequently amiable activity — 

 its playfulness of habit ; also, perhaps, as are many other 

 animals, as a corims vile for experiments in the way of 

 food. In an obliging way the two young occupants of the 

 Polar bears' cage will play with a bun or a biscuit ofi'ered 

 by some visitor who does not grasp the propensities of 

 animals with large canine teeth. To the naturalist the 

 Polar bear is interesting for other and different reasons. 

 It is one of the animals which have an absolutely descrip- 

 tive vernacular name. The Polar bear is one of the very 

 few mammalian creatures which are strictly Polar in range. 



