62 



KNOWLEDGE 



[March 1, 1894. 



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In Swift's comet (see photographs in Knowledge for 

 December, 18921 and in Brooks' comet (see the plate in 

 the last number of Knowledge) we seem to have evidence 

 of a series of tree-like and branching structures rising one 

 above the other. In this i-egion of the Milky Way fsee 

 Fig. 1) we have a somewhat similar series of tree-like 

 structures one above the other, apparently arising from the 

 same trunk or stream of outflow. Fig. 3 is a key diagram 

 SiHTH. to the plate 



; . •. • showing the 



■_ • "■ structures on 



.. ,;_ • the eastern side 



. \ '; \ .• • of the Orion 



' '. ' ■ ' - nebula. In the 



\ , • great branching 



structure which 

 seems to spring 

 from the east- 

 ern side of the 

 dense quadri- 

 lateral mass of 

 nebulosity sur- 

 rounding the 

 East. Trapezium, one 

 tree-like form 

 seems to rise 

 above another, 

 as if they be- 

 longed to suc- 

 cessive out- 

 bursts that were 

 being carried 

 along in a 

 stream 'flowing 

 outward from 

 the Trapezium 

 region. If this 

 is not the case, 

 and there is any 

 analogy be- 

 tween the 

 prominence- like 

 forms /', c and d (see index diagram, Fig. :-!) and solar 

 prominences, we must suppose that h, c and il have all 

 been projected from different centres of explosion. But 

 the cometary branching structures, which we naturally 

 assume all come from the nucleus or head of the comet, 

 seem to afford an explanation, or at least to throw some 

 light upon the process by which such structures could 

 take their form while passing through a resisting medium 

 near or around the seat of explosion, and might after- 

 wards be carried away in a stream as the matter of a 

 comet's tail is carried away. 



But tliere is a still more striking analogy between the 

 strange form presented by Brooks' comet on the 21st 

 October and this great structure in the Orion nebula. 

 One edge of the structure is much sharper than the other, 

 and it is curiously notched with sharply-deiined bays or 

 indentations on the side which is most sharply defined, as 

 is the case with the tail of the comet. In the Orion 

 nebula structure there are small as well as large notches. 

 Two of these small notches are very sharply defined in the 

 under-exposed pictm-e (reproduced in Fig. 2 of the plate). 

 They lie to the east of the lower part of the stem of the 

 structure marked h in diagram. Fig. 3. 



It is worthy of notice that the notched structure of the 

 Orion nebula is surmounted by a branching structure very 

 similar to the branching structure which surmounted the 

 notched region of Brooks' comet on October 21st, and that 



Fig. 3. — Diagram showing great curving 

 structure on the eastern side of tlie Orion 

 Xebuhi. 



there are other structures in the Milky Way and in nebula? 

 with one edge sharper than the other, and in which the 

 sharply-defined edge exhibits notches or indentations. 

 I would invite the reader to compare the plate of the 

 region of the Milky Way about ^ Cygni, published in 

 Knowledge for December, 1891, and any photograph he 

 may possess of the nebula near Orionis. 



In Thf Anwrican Xatiaalist for January, Mr. S. W. 

 WiUiston reports the discovery in the Niobrara Chalk, in 

 Kansas, of a Plesiosaurus skeleton, with which were 

 associated more than a hundred hard flinty pebbles, 

 varying in weight from 1 to 170 grams, and of conspicuous 

 colour. These he concludes had been swallowed by the 

 Plesiosaur to aid in digestion, a habit still in vogue among 

 crocodiles. 



Dr. Hickson, in his new book, The Fauna of the Deep 

 Sea, points out in a very vivid manner an extraordinary 

 danger to which the deep-sea fish are liable. At the great 

 depths at which they live the pressure is enormous — about 

 two and a half tons on the square inch at a depth of 

 two thousand live hundred fathoms. It sometimes happens 

 that in the excitement of chasing a prospective meal the 

 unwary fish rises too high above his usual sphere of life, 

 when the gases in the swimming bladder expand, and he is 

 driven by his increasing buoyancy rapidly to the surface. 

 If he has not gone too far when consciousness of his danger 

 grows greater than his eagerness for prey, the muscles of 

 the body may be able to counteract this, but above this 

 limit he will continue to float upward, the swimming 

 bladder getting more and more inflated as the unfortunate 

 creature rises. Death by internal rupture results during 

 this upward fall, and thus it happens that deep-sea fish 

 are at times found dead and floating on the surface of the 

 ocean, having tumbled up from the abyss. 



Notict of ISooit. 



Tlielhian of Astronomij : a Study'of the Teiiipti-M'orship 

 a)td Miithohu)!/ of the Aneieiit F.ijijptiaiu. V>y J. Xorman 

 Lockyer. London, 189-4. 



The idea upon which this work is based occurred to 

 Mr. Lockyer while inspecting the ruins at Eleusis, and 

 the remains of the Parthenon, in the spring of 1890. The 

 directions given to the foundation-lines of these buildings 

 struck him as peculiar, and implied, he rightly conceived, 

 an underlying motive. Old Christian churches, he 

 remembered to have heard, were often built so that, on 

 their respective feast-days, the rising sun should shine 

 directly through their eastern windows. Could it be that 

 this arrangement was merely a survival of an antique 

 practice "? He turned to Egypt for a reply. There, 

 numerous temples, dating from a grey fore-time, had been 

 measured by the French in 1798, and by the Prussians in 

 1844. There, too, astronomical considerations were known 

 to have been, in some cases at any rate, influential upon 

 architecture. The Great Pyramid is a standing example. 

 If our readers desire to satisfy themselves upon the point, 

 they need only refer to Mr. Proctor's demonstration in 

 " The Old and New Astronomy," that the tomb of Cheops 

 was used, some five thousand years ago, as a meridian 

 observatory. 



To Egypt, accordingly, our present author went both in 

 person and by manifold inquiries ; with results of most 

 curious interest. To some among them exception may be 



