566 



♦ KNOWLEDGE 



[May 5, 1882. 



to utilisp liis mighty energies, he is certainly not throwing 

 oflf matter constantly from liis ef)uatorial regions, as Dr. 

 Siemens' theory rciiuirts 



This being so, the theory failing thus in a matter abso- 

 lutely essential to its validity, %vi" may feel less tempted 

 than perhaps we otherwise might be to endeavour to ovev- 

 look other diliiculties, though these on careful consideration 

 appear scarcely less decisive. It might perhaps appear a 

 work of supererogation to consider difficulties when we 

 have already noted an impossibility. But some perhaps 

 will consider that, although the sun may not, after drawing 

 to himself the matter occupying space, reject it from him 

 in the manner supposed, he may reject it in some other 

 manner. If so, there might still be reason for inquiring 

 how far it is likely that the sun's rays may be utilised 

 when falling on the matter occupying space, in the way 

 suggested by Dr. Siemens. His iclea is that solar radiation 

 acting on the aqueous vapour and carbonic acid gas, and 

 other compound gases supposed to occupy interplanetary 

 and interstellar space, may dissociate such compounds, and 

 that solar energy may thus be utilised, instead of being 

 wasted. 



Now, if the rays of lirat (and light) are thus titilised 

 within the solar domain, regarding that if we please as 

 extending many times further than the orbit of Neptune, 

 they have either done their work and have been completely 

 utilised, or they have not. If they have done their work, 

 these rays proceed no further, and the sun would therefore 

 be invisible from any point outside his own domain. (For 

 we must not fall into the mistake of supposing that light 

 and heat can lie considered separately in this inquiry : 

 the se solar rays which give us what we call light, give us 

 also a large quantity of the solar heat, and the mystery of 

 seemingly infinite waste would remain, even if we supposed 

 that only those heat rays which are not also light rays were 

 utilised in the way supposed. Apart from this. Dr. Siemens 

 specially shows how the light rays act in accordance with 

 his \-iews.) Now, what is true of our sun is true of other 

 suns, the stars. They also ought to be invisible outside 

 their several domains, but as a matter of fact they are 

 ^Tsible. If, on the other hand, the solar rays have not 

 done their work in traversing what may be regarded as the 

 solar domain, the mystery of infinite waste is not removed, 

 scarcely even diminished, by Dr. Siemens' theory. If those 

 other suns, the stars, are able to send across the vast 

 distances which separ.ite us from them, such supplies of 

 light (to say nothing of stellar heat, which Huggins and 

 others have measured) that by measuring it we can say 

 that all of them are suns like our own, but many far larger 

 and giving out much more light than he — what is the 

 amount of work which we can suppose the stellar rays to 

 have done on their way 1 If they have done much (in 

 proportion to the total quantity which they are capable 

 of doing), then the stars must be very much larger, 

 brighter, and hotter than we suppose them to be, 

 and already we regard them as the rivals, and some- 

 thing more than the rivals, of our sun. If they 

 have done little, the mystery of infinite waste remains. 



In the case of the Siemens' regenerative furnace, we 

 know that the heat is utilised in the particular manner in- 

 tended, not only because we iind the heat so saved doing 

 its proper work, but because we find that this heat no longer 

 goes idly up the furnace chimney, as before. The heat 

 cannot be doing its full work in the furnace if part goes up 

 the furnace cliiiuney ; but also, part cannot be going up the 

 furnace chimney if the heat is doing its full work. This, 

 however, is what Dr. Siemens' theory requires the solar 

 heat to do. It is to be continually utilised in dissociating 

 compound vapours in interplanetary space, although it is 



continually passing beyond interplanetary space to shine 

 through interstellar space, and to show our sun as a .star to 

 worlds circling round his fellow stars the suns. We have, 

 in fact, the fallacy of the perpetual motion in a modified 

 form. 



^Ve are compelled, then, regretfully perhaps, but still 

 unhesitatingly, to give up that satisfaction which, as Dr. 

 Siemens remarks, we should gain, could we believe that 

 our solar system need " no longer impress us with the idea 

 of prodigious waste through the dissipation of energy into 

 space, but rather with that of well-ordered, self-sustaining 

 action, capable of perpetuating solar radiation to the re- 

 motest future." Yet though not in this way, to this end 

 all thoughtful study of the mechanism of the universe 

 seems unquestionably to tend ; not by centrifugal tendencies 

 of the kind imagined, for none such exist; not by work 

 which, viewed in reference to the universe as we know it, 

 means endless production without exhaustion ; but in other 

 ways (associating perhaps our visible universe with others, 

 permeating it as the ether of space permeates the densest 

 solids, and in turn with others so permeated by it) there 

 may be that constant interchange, that perpetual harmony, 

 of which Goethe sung — 



See all things with each other blending, 



Each to all its being lendinfj, 



Each on all in tiu-n depending : 



Heavenly ministers descending, 



And again to Heaven uptending, 



Floating, mingling, interweaving. 



Rising, sinking, and receiving — 



Each from each, while each is giving 



On to e.^ch, and each relieving 



Each — (he pails of gold. The living 



Current through the air is heaving;; 



Breathing blessings see them bending. 



Balanced worlds from change defending. 



While everywhere diffused ia harmony unending. 



From the dtrnhill Mngaztnc. ^ 



Since this article appeared in the Cornhill ilagaziiie. 

 Dr. Siemens has called my attention to a letter of his in 

 Xature, in which he answers the objection relating to the 

 centrifugal force. Next week I shall endeavour to find 

 space for his reasoning in exfenso ; but here I must content 

 myself by noting that it amounts simply to this : That 

 taking two equal portions of gaseous matter at equal 

 density and temperature, and equi-distant from the sun's 

 centre, one at the sun's pole, the other at the equator 

 (sharing in the sun's motion of rotation), the former is 

 drawn with greater force towards the centre of the sun 

 than the latter, — and that, therefore, a polar inflow and an 

 equatorial outflow must take place, provided only that 

 space is not empty, as supposed by Laplace, but fiUed 

 with either an elastic or non-elastic fluid. This rea- 

 soning shows undoubtedly that under the imagined con- 

 ditions there would not be equilibrium, and therefore 

 those conditions would not exist. Motion would take 

 place until equilibrium was obtained. But no one 

 familiar with the mathematics of hydrodynamics wUl, on 

 consideration of the matter, maintain (though, by a passing 

 forgetfulness, he might assert) that, even if the impossible 

 conditions suggested by Dr. Siemens could exist for a 

 moment, the absence of equilibrium would lead to con- 

 tinuous motion outwards in the sun's equatorial plane. The 

 surfaces of equal pressure would pass from the spherical to 

 the spheroidal form, and would for a time oscillate on either 

 side of the form they %\ould finally assume ; but there 

 would be no continuous motion either of inflow or of 

 outflow. I may note, further, that Dr. Siemens' view 

 respecting what Mairan supposed, and Laplace disproved, 

 is not correct. Ilis comparison also between the loss of 



