Dec. 23, 1881.] 



♦ KNC^A^LEDGE 



157 



liooks (I was nearly saying " as is now the fashion"), 

 sicing that they are not the actual figures obtained by his 

 ' xpcriiiients, but thoso of his "empirical formul;*;" based 

 iilion them. His actual experimental figures are very 

 irregular; thus, between steam temperature of 171 '6° and 

 1S3*2^ a difference of 11 '6°, the experimental difference in 

 tlie latent heat came out as 4 '7° ; between steam temperature 

 of 183 -2° and 194 -8^, or 11-6° again the latent heat differ- 

 once is tabulated as 80°. 



Regnault's experiments were not carried to very high 

 trinperatures and pressures, and indicate that as these 

 ad\ ance the deviation from Watt's law diminishes, and may 

 liiially vanish at about 1,500° or 1,600^, where the latent 

 lieat would reach zero, and there, according to the above, 

 tlu- critical temperature woidd be reached. Any additional 

 heat applied after this will have but one function to per- 

 form, viz., the ordinary work of increasing the bulk of the 

 heated body witliout doing anything further in the way of 

 conferring upon it any new self-repulsive properties. 



Our notions of solids, liquids, and gases are derived from 

 our experiences of the state of matter here upon this earth. 

 L'ould we be remo\cd to another planet, they would be 

 curiously changed. On Mercury water might rank as one 

 of the condensible gases ; on Mars, as a fusible solid ; but 

 what on Jupiter ' 



Recent observations justify us in regarding this as a 

 uiiniature sun, with an external envelope of cloudy 

 matter, apparently of partially condensed water, but red- 

 hot, or probably still hotter within. His vaporous atmo- 

 sphere is evidently of enormous depth, and the force of 

 gravitation being on his visible outer surface 2| times 

 - ater than that on our earth's surface, the atmospheric 



'ssure in descending below this visible surface must soon 



cch that at which the vapour of water would be brought 



its critical condition. Therefore we may infer that the 



■ans of Jupiter are neither of fi-ozen, liquid, nor gaseous 

 ■■■ ater, but are oceans or atmospheres of critical water. If 

 any fish-l)irds swim or fly therein they must be very 

 critically organised. 



As the whole mass of Jupiter is 300 times greater than 

 that of the earth, and its compressing energy towards the 



litre proportional to this, its materials, if similar to those 

 : the earth and no hotter, would be considerably more 



use, and the whole planet would have a higher specific 

 '.gravity, but we know by the movement of its satellites 

 tliat, instead of this, its specific gravity is less than a 

 fourth of that of the earth. This justifies the conclusion 

 that it is intensely hot, for 'even hydrogen, if cold, would 

 become denser than Jupiter under such pressure. 



As all elementary substances may exist as solids, liquids, 

 or gases, or, critically, according to the conditions of tem- 

 perature and pressure, I am justified in hypothetically 

 concluding that Jupiter is neither a solid, a liquid, nor a 

 gaseous planet, but a critical planet, or an orb composed 

 internally of dissociated elements in the critical state, and 

 surrounded by a dense atmosphere of their vapours, and 

 those of some of their compounds, such as water. The 

 same reasoning applies to Saturn and the other large and 

 rarefied planets. 



The critical temperature of the dissociated elements of 

 the sun is probably reached at the base of the photosphere, 

 or that region revealed to us by the sun-spots. When I 

 wrote "The Fuel of the Sun," thirteen or fourteen years 

 ago, I suggested, on the above ground^, the then heretical 

 idea of the red-heat of Jupiter, Saturn, Uranus, and 

 Neptune, and showed that all such compounds as water 

 must be dissociated at the base of the sun's atmosphere, 

 but being then unacquainted with the existence of this 

 critical state of matter, I supposed the dissociated elements 



to exist as gases with a small solid nucleus or kernel in the 

 centre. 



Applying now the researches of Dr. Andrews to the 

 conditions of solar existence, as I formerly applied the 

 dissociation researches of De\-ille, I conclude that the 

 sun has no nucleus, either solid, liquid, or gaseous, but is 

 composed of dissociated matter in the critical state, 

 surrounded, first, by a flaming envelope due to the re- 

 combination of the dissociated matter, and outside of this 

 another envelope of vapours due to this combuiation. 



THE EVOLUTION OF MAN. 



By Dk. a. Wilsox, F.R.S.E. 



IX letter 103, " G. M." asks, " has evolution effected any change in 

 man ? If so, what change ? If not, why not ? " These are 

 weighty questions, and " G. M." will tind difficulty in answering 

 them. Let him remember firstly that evolution has only been 

 studied — rather nature, in the light of evolution, has only been 

 studied — for some twenty-five years or so. That is, of course, a 

 mere fractional space in the history of human thought. If we re- 

 fuse to admit (as science does) that man was created a perfect 

 being, and then became degraded, there exists only another sup- 

 position — that of evolution. If man has arisen from a savage to a 

 civilised state, that surely is evolution. We do not yet know, 

 because such knowledge is difficult to acquire, if the human frame 

 is subject to the same influences as those of lower animals. But 

 there is little doubt that elevation from savagery to cirilised life 

 means and implies " evolution," and that of considerable extent. 

 Mentally, man's evolution cannot bo doubted ; the ever-widening 

 sphere of thought has sprung from small and rude beginnings, 

 like language itself. But man's wai,-s of life, his power of adapta- 

 tion to his surroundings, and countless other circumstances, have 

 made the facts and course of his " evolution " very difficult to trace. 

 If " G. M." will read Tyler's "Anthropology" (Slacmillan) he will 

 find there summarised facts and phases of human life which go 

 powerfully to answer the interesting queries he puts to Knowledge. 



MALLET'S SEISMOMETERS. 



THE " Encyclopa-dia Britannica," 9th edition, "Earthquake," 

 mentions and describes a seismometer of extreme simplicity : — 

 " Its construction, which is due to Mr. Mallet, will be understood 

 by reference to the figure. Two sets of right cylinders are turned 

 in some hard material, such as boxwood. The cylinders are all of 

 the same height, but vary in diameter. Two planks of wood are 

 fixed to a level floor, one having its length in a north and south, and 

 the other in an east and west direction. The cylinders stand 

 upright on the planks in the order of their size, with a space 

 between each pair greater than their height, so that when one 



pillar falls it does not strike its neighbour. The surroimdiug floor 

 is covered np to the level of the planks with dry sand. When a 

 shock passes, some of the cyUnders are overturned, the number 

 depending on the velocity of the wave. Suppose the shock knocks 

 over the narrow-based cylinders 4, 5, 6, leaving 1, 2, 3 standing, 



