56 



NATURE 



IMay 20, 1880 



is the more astonishing that these little Crustacea are 

 found in almost every Bromeliad. 



It cannot but sometimes happen that a few specimens 

 must be washed away into other waters, as on the 

 contrary, one may sometimes meet with a stray entrapped 

 Cyclops' that has slipped into the Bromeliads. Yet Fritz 

 Miiller has hitherto searched in vain for Elpidium in 

 running waters, which produce, among other species, 

 Cypris, Cyclops, Canthocamptus, Chydorus, Alona, Camp- 

 tocercus, Pasithea, Moina, Ceriodaphnia, Simocephalus, 

 &c. It seems not to flourish outside the Bromeliads. 



[Translated from Kosmos, February, 1880. Elpidiutn 

 comes somewhat near to Elpidia, Theel. — E. P. W.] 



ON THE PHYSICAL ASPECTS OF THE 

 VORTEX- ATOM THEORY 



IN all attempts to arrive at a satisfactory conception of 

 the iiltimate constitution of matter, the grand difficulty 

 has hitherto been to reconcile the proved indestructibility 

 of the atom with its capacity for executing vibrations, as 

 demonstrated by the spectroscope. The ancients, by 

 assuming the atom to be infiiiiti'Iy hard, attempted in this 

 way to get over the difficulty of indestructibility (or in- 

 divisibility), but thereby debarred all means of conceiving 

 the " elasticity " of atoms, or their known powers of taking 

 up vibrations of difterent periods. 



When we consider the immense difficulty that there 

 must have been in conceiving how an atom could be 

 elastic {i.e., how its parts could be capable of free motion) 

 and yet its parts be incapable of separation from each 

 other, we may well excuse the attempt to explain inde- 

 structibility by the assumption of the quality of infinite 

 hardness, unsatisfactory though it might be. 



It is evident that if we are to renounce all idea of occult 

 qualities of "elasticity," hardness, indivisibility, &c., and 

 purpose to explain the facts without recourse to postu- 

 lates, we must assume the material substance of which 

 our atoms are to be formed, to be itself entirely without any 

 positive qualities, i.e., to be without elasticity, hardness, 

 rigidity, &c., and therefore to be freely penetr.able in all 

 parts, or perfectly passive and inert. This is the perfect 

 liquid of the vortex-atom theory. There may be some 

 who would say that it is difficult to conceive of such a 

 liquid. On the contrary, we venture to be able to prove 

 that such a liquid alivays is conceived of ^shtnevsY a. liquid 

 is thought of Thus, does any one in conceiving of a 

 liquid (water, for instance), regard the liquid as consisting 

 of solid {i.e., more or less rigid) portions of matter sliding 

 over each other [as we might conceive solid masses 

 sliding past or through each other on a magnified scale]; 

 and yet this is truly what the liquid (composed of mole- 

 cules) is in the actual fact. In short it is not a "liquid" 

 at all. Yet we conceive of it as liquid, i.e., freely pene- 

 trable in all parts. We therefore contend that a perfect 

 liquid (or true liquid) is what is always conceived of, and 

 therefore that there can be no difficulty in regard to the 

 conception of the true Uquid that forms the" basis of the 

 vortex-atom theory. 



In the next place, it is an obvious condition to any con- 

 sistent conception of matter that matter must possess 

 extension,^ or occupy space, i.e., so that two portions of 

 our liquid cannot occupy the same space at the same time. 

 If, therefore, the liquid fills all space, it must be incom- 

 pressible. This is, therefore, not an arbitrary postulate. 



The next question naturally suggesting itself would be, 

 how are portions of such a liquid to attain the properties 

 that we recognise in atoms ? We venture to think it will 

 be conceded as evident that the only conceivable way (if 

 it be admitted that the result is attainable at all) is through 

 motion [for this is the only conceivable way in which the 

 liquid can be affected]. The further inquiry would there- 



i be regarded as included in the dcfini- 



fore be, what would be the character of this motion ? Now, 

 in order to fulfil the condition that the atom itself can be 

 brought to rest without losing its properties as an atom, 

 it is evident that the motion of the material forming it 

 must take place in such a way that the atom can remain 

 in one spot, or be to our senses at rest, i.e., the material 

 of the atom, although in motion, must not deviate from 

 one spot. We ask if there is any other conceivable 

 form of motion than rotary motion that would fulfil this 

 condition.'' Hence the necessity for looking to rotary 

 motion as the basis of the properties of the atom. In the 

 next place a portion of material in rotation must rotate 

 about an axis. If the ends of this axis were exposed, we 

 should have two points at rest, which would forfeit the 

 condition of motion being the essential basis of the 

 external qualities of our atom. The question is, therefore, 

 how is a portion of material to be in rotation about an 

 axis, and yet not expose the ends of the axis ? The only 

 conceivable answer (as we think will be admitted) is that 

 the rotating portion of material must have the form of a 

 closed ring, or complete circuit, so that the axis has no 

 ends. We therefore think it may be said beforehand that 

 conceding that the problem of the atom can be solved at 

 all (or if it be conceded that a fact can exist solely in 

 virtue of the explanation that underlies it) then the problem 

 could only conceivably be solved under the fundamental 

 conditions above developed, i.e., under the condition of a 

 portion of material (having no positive properties in itself) 

 rotating in the form of a closed circuit. 



This (as is well known) is what has been found to 

 satisfy the conditions for the atom by the application ot 

 mathematical analysis (without, apparently, that object 

 ha\-ing been in view at all), and in a manner the most 

 remarkable in its completeness. It appears possible, in 

 view of the above considerations, that a profound and 

 competent thinker who had devoted himself to the subject 

 might have arrived, even before the mathematical analysis 

 had been applied, at the sole conceivable physical condi- 

 tions that in principle could satisfy the problem of the 

 atom (admitting the existence of the solution) ; but the 

 mathematical analysis can of course alone make .the fact 

 of the solution apparent to us. It is related in the article 

 on " The Atomic Theory of Lucretius " {North British 

 Review, March, 1868) that Hobbcs had arrived at the 

 fundamental idea that the rotation of a portion of material 

 must be the basis to the solution of the problem of the 

 "elasticity" of the atom, without having applied any 

 mathematics. 



The difficulty of the mathematical side of the yortex- 

 atom theory is curiously contrasted with the simplicity of 

 the physical side of the theory. If we suppose a cylin- 

 drical bar of india-rubber to be rotated about its longi- 

 tudinal axis, and the bar (still rotating) to be bent round 

 into a ring shape and the ends joined (the rotation of the 

 material of the ring being always continued), then this 

 may serve to illustrate in a simple way the motion of the 

 material forming the vortex-atom. It is here apparent 

 that the material of the india-rubber ring (in our illus- 

 trative case) may be in rapid motion while the ring itself 

 preserves a fixed position in space. It would seem to be 

 a pity if a spurious mystery should be allowed to envelope 

 this subject, which is unworthy of it, in view of the sim- 

 plicity of its physical basis. No one doubts the difficulties 

 that had to be surmounted on the mathematical side ot 

 the theory, but there is all the more reason on that account 

 that the extreme simplicity of the physical side of the 

 theory should be duly appreciated, and unnecessary 

 obstacles not be thrown in the way of its adoption. The 

 tendency to invest physical subjects with a halo of the 

 occult [possibly partly attributable to the unfortunate 

 introduction into physical science of the spiritualistic con- 

 ception of ">;tc"— in the sense of an action across 

 space without the intervention of matter] has probably 

 done more to hinder progress than any real difficulties. 



