184 



KNOWLEDGE 



[October 2, 1893. 



eclipse of 1492. The northward pace was now notably 

 slackened. In 1654 north latitude 48° was reached, and 

 the eclipse was total in England — the last one total in 

 this country except the celebrated pair of eclipses of 1715 

 and 1724. Three returns later, in 1708, north latitude 

 53° was reached ; but shortly after this, the turning of the 

 north pole from the sun caused the shadow to appear to turn 

 southwards, and when it had reached the winter solstice 

 the latitude had fallen to north latitude 36°. This was 

 the celebrated eclipse of December 22nd, 1870, to observe 

 which M. Janssen escaped fi-om besieged Paris in a balloon. 

 But now that the eclipse has passed the solstice, and the 

 north pole is beginning once again to turn towards the sun, 

 the latitude of the central shadow wUl move northwards 

 with great rapidity, and by 2015 will have reached north 

 latitude 85°. At the next return the shadow-track, though 

 not yet quite clear of the earth, will pass above the north 

 pole, and the eclipse will be total for the last time. 



The effect of the triple Saros in reproducing, not only 

 the general conditions of an echpse, but also the very hour 

 and locahty, is very strikingly seen in the two eclipses of 

 1708 and 1762. Here the shadow track is nearly the same 

 in both cases, and the central point has only shifted a few 

 miles, lying in both instances near the boundary hne 

 between Europe and Asia, between the towns of Samara 

 and Orenburg. Curiously enough — but this must be looked 

 upon as a mere chance coincidence — the same eclipse will 

 have its centre a third time in the same place, viz., in 

 1961 ; but the general direction of the shadow-track will 

 then be very different. 



The shadow-track at the third return after 1762, viz., 

 in 1816, again runs in a similar direction though the 

 central point has shifted, and for the third time Norway 

 is the seat of a total eclipse. The next triple Saros brings 

 us to the 1870 eclipse, when the track had shifted south- 

 ward for a time. 



Such are a few of the relations produced by the in- 

 commensurability of limar and terrestrial movements, 

 combined with a curiously close approach to a precise 

 commensurability. These are only a few of them, for I 

 have entirely ignored the eclipses of the moon, or the solar 

 ecUpses at the opposite node, which of course have both a 

 very definite relation to the series I liave been considering. 

 Still less have I included the numerous luni-solar cycles 

 which, though useful for other purposes, have no relation 

 to echpses. The paper has, however, already proved very 

 long, and may have been sufficient to have called attention 

 to a subject in which less interest is taken at present than 

 used formerly to be the case. 



WHALEBONE AND WHALEBONE WHALES. 



By R, Ltdekker, B.A.Cantab. 



SEEING that the substance so-called has nothing in 

 common with true bone, many zoological writers 

 object tothe use of the term "whalebone "; and they 

 have accordingly proposed the substitution of the 

 word " baleen," which has been specially coined 

 for the purpose. To our thinking, there is, however, no 

 necessity for this substitution of a word of foreign origin 

 for such a well-known English name, any more than there 

 is for replacing the native term " black lead " by its foreign 

 equivalent " graphite." Everybody knows what is meant by 

 whalebone or black lead, while comparatively few are 

 familiar with the terms " baleen" and "graphite" ; and as 

 the two foi-mcr are every bit as good as their foreign sub- 

 stitutes, we prefer to employ them. If, indeed, there 

 should exist any persons so misguided as to imagme either 



that whalebone is equivalent to the bone of whales, or that 

 black lead has any sort of affinity with lead, we fear that 

 the substitution of the terms "baleen" and "graphite" 

 would not much aid in removing their ignorance. 



The substance which we accordingly take leave to call 

 whalebone is one of the chief essential characteristics 

 by which the whalebone whales are distinguished from 

 the toothed whales forming the subject of our article in 

 the preceding number of Knowledge. As all our readers 

 are probably aware, this substance is attached to the upper 

 surface of the mouth of the whale, from which it depends 

 in the form of a series of parallel, narrow, elongated, 



Scotiou through the skull of the Greenland Whale, with the outline 

 of the soft parts, s indicates the position of the nasal aperture. 



triangular plates, placed transversely to the long axis of 

 the mouth, with their external edges firm and straight, 

 but the inner ones frayed out into a kind of fringe. The 

 longest plates of whalebone are situated near the middle 

 of the jaw, from which point the length of the plates 

 gradually diminishes towards the two extremities, where 

 they become very short. There is, however, whalebone and 

 whalebone, and whereas in the Greenland whale the length 

 of the longest plates varies from some ten to twelve feet, 

 while the total number of plates in the series is about 380, 

 in the great rorquals or fin-whales, the length is only a few 

 inches, while the number of plates is considerably less. 

 To accommodate the enormous whalebone plates of the 

 Greenland whale, the bones of the upper jaw are greatly 

 arched upwards, while the slender lower jaw is bowed out- 

 wards, thus leaving a large space both in the vertical and 

 horizontal directions, the transverse diameter of the space 

 being much wider below than above. When the mouth is 

 closed, the plates of whalebone. are folded obliquely back- 

 wards, with the front ones lying beneath those behind 

 them ; but directly the jaws are opened, the elastic nature 

 of this wonderful substance causes it to spring at once into 

 a vertical position, and thus form a sieve-like wall on both 

 sides of the mouth, the thin ends of the plates being pre- 

 vented from pushing outwards by the stiff' lower lip which 

 overlaps them. By elevating its enormous fleshy tongue 

 within the cavity thus formed, the whale causes the 

 enclosed water to rush out between the plates, leaving such 

 small creatures as it contained lying high and dry on the 

 surface of the tongue ready for swallowing. 



In structure, whalebone (which, by the way, although 

 black in the Greenland whale, is white in some of the 

 other species) is of a horny nature, and grows from 

 transverse ridges on the mucous membrane of the roof of 

 the mouth ; being, in fact, nothing more than an ultra- 

 development of the ridges on the palate of a cow, hardened 

 and lengthened by an excessive growth of a horny super- 



