5i8 



NA TURE 



[September 2S, 1891 



would describe the same curves as Ihey do now. The appear- 

 ances presented to observers would be the same, and indepen- 

 dent of the dimensions assumed. Hence the only facts we are 

 able to appreciate are ratios. In opposition to this theorem, 

 M. Delbceuf shows that if a system consisting of the sun and 

 earth were lo be diminished in linear dimensions to one-half, 

 all densities remaining the same at homologous points, and the 

 orbital velocity of the earth were reduced to one-half its value, 

 there would be certain changes in the relations of an observer 

 to his surroundings which could not escape notice. The velocity 

 of sound propagation wouli be the same as before, but the dis- 

 tance traversed during a certain number of vibrations will appear 

 larger," &c. (p. 406 of Nature). 



Here it seems to be overlooked that according to the above 

 system of reduction of scale, the molecules of air which propagate 

 sound would have to be conceived as diminished in size corre- 

 spondingly with the planets, earih, &c., for if not, obviously the 

 constancy of ratio of relative dimensions supposed by I.aplace 

 could not persist under this reducing process. For, considering 

 "all the bodies in the universe," we cannot regard the linear 

 dimensions of the earth and larger bodies as reduced to one- 

 half, and neglect the smaller bodies (molecules). If then the 

 dimensions of the molecules of air, and also their normal veloci- 

 ties be supposed reduced to one-half, then (according to what is 

 set forth in a paper of mine in the Philosophical JMagazine^ June 

 1877, relating to sound), the velocity of sound would be 

 exactly halved, and therefore not remain " the same as before," 

 as M. Delbceuf supposes. But the velocity of sound would 

 appear the same as before to us with our halved standards of 

 length on the reduced planet, in accord with what Laplace 

 states. For as indicated in the above paper {P!iU. .I/a/.l, 

 "The velocity of propagation of a wave^such as a wave of 

 sound — in a gas is solely determined by, and proportional to, 

 the velocity of the molecules of the gas ; and the velocity of 

 propagation of the wave is not affected by density, pressure, or 

 by the s, ecific gravity of a gas, or by anything else excepting 

 the velocity of its molecules" (p. 452.) 



For, on the Kinetic theory, the molecules of a gas can 

 evidently only act upon each other by direct impact, and they 

 therefore propagate any wave at their encounters at a rate pn>. 

 portional to that at which the molecules are moving in the 

 normal slate of the gas. If, we imagine then, the velocities of 

 the smaller bodies (such as the molecules of air) to be halved, 

 just as those of the planets, &c., are supposed halved, then the 

 velocity of sound will be necessarily reduced to one-half, as we 

 have seen. 



Hence the above argument based on the Kinetic theory of 

 gases would apparently support Laplace's view ; and so the 

 velocity of sound would seem to us precisely the same as before. 

 The distance traversed during a certain number of vibrations 

 would not then (as M. Delbceuf thinks) appear larger; all hi; 

 conclusions seem to me invalidated by his assumed tinsyminetri- 

 cal selective diminution of sizes. Of course one-half the 

 present metre would on the reduced earth be still called a 

 " metre," because it would be a ten-millionth of the earth's 

 quadrant, as now. A man a metre high would still be a metre 

 high in the planet of reduced size, and the metre standard he 

 grasped would still be the same length as himself. So it appears 

 that if the universe known to us were suddenly halved in size by 

 reducing the linear dimensions and velocities of all the bodies 10 

 that extent, there would be nothing to allow the change to be 

 detected. This would also seem to harmonise with the 

 Spencerian doctrine of the Relativity of all knowledge. 



Hamburg, September 4. S. Tolver PRiisroN. 



EARL Y ASTERISMS:- 

 II. 

 A S in Egypt so in Babylonia, for the first refer- 

 ■^^^ ences to the constellations we must study the 

 religion and the mythology ; Jensen shows that the first 

 notions of the Babylonian constellations are to be got^by 

 studying the sun-gods, and especially the mythic war 

 between the later sun-god Marduk and the monster 

 Tiiimat. 



1 " Mode of the Propagation of Sound and the Physical Conditions which 

 aetermine its Velocity on the liasis of the Kinetic Theory of Gases." 

 * Continued from p. 440. 



NO. 1248, VOL. 48] 



So far as I have been able togather,any myth like 1 

 Egyptian myth of Horus involving combats between t 

 sun and circumpolar star-gods is entirely lacking 

 Babylonia, but a similar myth in relation to some of ij 

 ecliptic constellations is among the best known. " ! 



In my references to the myth of Horus I have sho\ 

 that in all probability an astronomical meaning is th 

 the rising sun puts out the northern stars ; and there 

 evidence that we have a reference also toasun-worshippi 

 race abolishing the cult of Set representing the northe 

 stars. I have also shown that temples built to nonhe 

 stars have had their axes blocked to prevent the worsh; 

 and that the northern temples at On and Denderah we 

 among the first founded for the v/orship of the Divi; 

 dynasty of Set or Anubis. 



This being so, it is of importance to discuss the Bab 

 Ionian myth of the battle between Marduk and Tiam 

 from the astronomical point of view, but before we i 

 this it will be well to see if one can trace the history 

 the sun-god of Eridu, which city is universally concedi 

 to have been the original centre of Babylonian ide 

 until the descent of the Xorthmen, and to have bet 

 founded by a colony from some other country. 



The Sun-god of Eridu. 



Let us assume that the earliest sun-god traced , 

 Eridu was the sun-god of those early argonauts wt 

 founded the colony. 



We are told that this sun-god was the son of la ar 

 Dam-kina, his wife symbolising the earth, and that h 

 name was Tammuz (Sayce, p. I4-|.).^ 



This la was such a great god that to him was assignc 

 the function of Maker of Men ; he was also a great potti 

 and art workinan (p. 293), a point I shall return to pn 

 sently. He eventually formed a triad with hxwx and B 

 that IS, the poles of the heavens and the equator. Th 

 Tamirtuz (Dumazi) was afterwards identified with Nil 

 Girsu, and ultimately became " the Nergal of Souther 

 Chaldffia, the sun-god of winter and night, who rule 

 like Rhadamanthos, in the lower world" (Sayce, p. 245 

 and as lord of Hades he was made son of Mul-hl (Sayo 

 P- 197)- 



This was at first. But what do we find afterwards? 



Nergal is changed into the Midsummer Sun ! (Jensen 

 p 484). And finally he is changed into the Spring Su 

 Maidukat Babylon (Sayce, p. 144) where he is recog 

 nised as the son of la and Duazag,; that is the Easter 

 Mountain (Jensen, p. 237). 



Now however difficult it may be to follow these change 

 from the religious point of view, from the astronomica; 

 side the changes are not only easily explained, bat might 

 have been predicted, provided one hypothesis be permitted 

 namely, that the colony who founded Eridu were origin 

 ally inhabitants of some country south of the equator. 



Such an hypothesis may at first sight appear strange 

 but the view that Eridu was colonised from Cush hai 

 been supported by no less an authority than Lepsius.' 



Now the boundaries of Cush are not defined, but the; 

 may possibly include the Land of Punt from whici 

 certainly part of the Egyptian culture was derived. 



Punt was always considered a " Holy Land," and i 

 was acknowledged that several of the Egyptian godi 

 had been thence introduced. Hathor was " f2ueen of th( 

 Holy Land," " Mistress and Ruler of Punt." Amen R; 

 was "Hak" or "King" of Punt, and Horus was thf 

 Holy Morning Star which rose to the west (.'j of the lanii 

 of Punt.-' 



Maspero refers to an ancient tradition that the land ol 

 Punt could be reached by going up the Nile, where 



1 It would seem also that Isara = Tammuz. This connects the myths o 

 Isis and Osiris, Tammuz and Adonis, and the cult at Byblos (see Sayce 



p. 3Z3). 



- Introduction to Nubische Grammatik, i83o. 

 ^ Rawlinson, ii. 134. 



