6o 



NA TURE 



[May 15, 1 1 



condition which obtains exceptionally in the spots. The 

 "granulated" texture of the photosphere is the result of 

 the eruptive pressure of the internal hydrogen, upheaving 

 and penetrating the glowing mass of iron. The faculas 

 owe their greater elevation and intensity to an increased 

 activity of the same process ; and the chromosphere and 

 the protuberances, whether of the more eruptive or more 

 cloudy character, are traceable to the same origin, the 

 greater brilliancy of the former class being due to the ad- 

 mixture of metallic vapours with the all-pervading hydro- 

 gen. The iron shell is not everywhere in a state of equal 

 fluidity, a considerable portion being in a more " pappy " 

 or viscous condition, such as may be seen in our own iron 

 furnaces, which, however, does not render its presence 

 manifest without such a reduction of temperature as to 

 produce opacity. This cooling does not obtain either in 

 the equatorial or polar regions, but is effected in what are 

 known as the " spotted zones," by the overflow of hydro- 

 gen from the loftier equatorial strata of the atmosphere. 

 Here, the gas, having been carried up in consequence of 

 the solar rotation into a higher and cooler region, and ex- 

 tending itself laterally as an " equatorial current," descends 

 on the less fluid portions of the photosphere, whence 

 radiation is not so free ; they are thus reduced to the more 

 scoriaceous and opaque condition in which they assume 

 the well-known appearance of " spots," while the whirls 

 of cooler vapour on the outside of the main column in its 

 downpour, encountering and tearing away the adjacent 

 metallic edges of the chromosphere, force them to assume 

 the form of those radiated fringes which we know as 

 " penumbrae." The maxima and minima of the spots, as 

 well as their respective drifting towards the poles or the 

 equator, find their explanation in a " pulsation " or alter- 

 nate compression and expansion of the globe, chiefly in 

 the direction of its axis, from corresponding alternations 

 in the balance of internal condensation and temperature, 

 each of which is supposed to be in its turn in the 

 ascendant ; and though the change of dimension is slight, 

 it is sufficient to give preponderance either to the equa- 

 torial or polar current, and, combined with the rotation, 

 to determine the periodicity of the frequency and range 

 of the spots. On the whole, the energy of solar radiation 

 is never compensated ; but the waste is so gradual that 

 we have no reason to anticipate any sensible effect for 

 ages to come, and yet so sure that the progressive cooling 

 must terminate in ultimate extinction. In our author's 

 words, " When in some future period of the world the 

 whole of the hydrogen has escaped from the solar nucleus, 

 the sun will cease to shine with its wonted intensity, and 

 will become more and more feeble till at length it hangs 

 in the firmament, a mighty globe of glowing red, as seen 

 from other worlds a ruddy star, which, through rapid 

 cooling, becomes visibly obscured, and, from the forma- 

 tion of everywhere surrounding scoriae, immersed in deep 

 night," — a termination of which it may be said that, what- 

 ever its intrinsic probability, no reader need look forward 

 to it with the slightest personal apprehension. And were 

 that resplendent body, as Kepler in the exuberance of his 

 imagination believed, the abode of glorious spirits, they 

 might perhaps be supposed to smile at all such anticipa- 

 tions as utterly foreign to the unsearchable designs of the 

 All-wise Creator. 



And yet we may not forget that there have been, from 

 time to time, mysterious warnings among the innumerable 

 suns that have their abode in the far depths of space, and 

 we are reminded by no process of argument, but by the 

 evidence of our senses, how untrue it is that " all things 

 continue as they were from the beginning of the creation." 

 The certainty of strange and wonderful catastrophes of 

 outburst or extinction has come to our knowledge, thnugh 

 perhaps only after centuries, or it may have been ages, of 

 the transmission of the recording light : and similar 

 events, to be recognised only by long-distant generations, 

 may be in progress at the present hour. We know very 



little of the history of the universe, and it becomes us 

 well to speak of such possibilities with caution and rever- 

 ence. Meanwhile we owe a debt to all who will aid us in 

 the attempt to gratify a very natural curiosity, and to our 

 author among the rest. Some portion of his hypothesis 

 does not come before us for the first time. La Hire in 

 very early days entertained the notion of opaque bodies 

 floating in a fluid mass and occasionally appearing on its 

 surface ; and the conclusions of Gautier were very similar 

 as to a partial solidification of metal in fusion ; but we 

 must bear in mind that it is only for the diffusion of 

 hydrogen through a liquid envelope of iron that our 

 author claims originality. His ideas are expanded and 

 enforced by so much elaborate reasoning as at any rate 

 to deserve perusal, if they do not succeed in producing 

 conviction. As to this point we may freely confess that 

 the author is more sanguine than ourselves. Some of his 

 arguments are well worthy of attention ; but the general 

 character of the treatise is that of an ingenious piece of 

 special pleading, one-sided, but fair and honest in its self- 

 persuasion. A few omissions and mistakes might be 

 pointed out, but they do not impair his argument. The 

 weakness of this, as our readers will have already per- 

 ceived, lies in the magnitude of some of its assumptions. 

 It might indeed be said that the same objection lies 

 against each of the more commonly received theories : 

 and to this it can only be replied that, though similar in 

 character, it differs in amount ; and that the value of any 

 attempt at explanation must be estimated in the inverse 

 ratio of its unproved demands upon our assent. 



T. W. Webb 



THE EARTHQUAKE 

 TN a previous notice (p. 17) brief mention was made of 

 *■ the more obvious conclusions which follow from a 

 consideration of the observed effects of the earthquake 

 of April 22. Mention was also made of some points upon 

 which further knowledge would be of value, notably as to 

 the result of the earthquake upon wells and springs. Mr. 

 De Ranee's letters give important information upon 

 this matter. 



The measurements of the water in wells at Colchester 

 and Bocking prove that the level of the water has risen 

 seven feet in the former case and from twenty to thirty 

 inches in the latter case. These facts, and also the curious 

 instance of water spouting from the ground at East 

 Mersea, are quite in accord with what frequently occurs 

 during earthquakes. Mr. Mallet says : — " Fissures con- 

 taining water often spout it up at the moment of shock. 

 Wells, after the shock, alter their water-level, and some- 

 times the nature of their contents ; springs become altered 

 in the volume of water they deliver. ... It is important 

 to observe whether any changes of level of water in wells 

 take place prior to earthquakes. Statements to this 

 effect have frequently been made, but as yet stand much 

 in need of confirmation." 



Dr. Taylor's observations that the new and often 

 slightly-built houses have generally suffered less than the 

 old and more solid structures is scarcely what one would 

 have expected. In districts much subject to earthquakes 

 the houses are generally built in such a manner that they 

 yield readily to the vibration, and so mostly escape serious 

 damage. Mr. Mallet indeed believes that if this custom 

 were enforced very little damage would be done. As re- 

 gards larger and more important structures, the question 

 is not so easily settled ; and Messrs. D. and T. Stevenson, 

 in constructing the lighthouses of Japan, employed a pecu- 

 liar and ingenious contrivance for guarding against the 

 effects of earthquake shocks : this was to interpose a 

 break in the rigid part of the building, and so to prevent 

 the propagation of the shock. Mr. D. Stevenson, in de- 

 scribing this, says : — " The plan I propose for this purpose, 

 which may for brevity be termed an aseismatic joint, is 



