266 



KNOWLEDGE 



[Sept. 1:>, 1882 



with motor impnlses starfoil by the will, gives to a certain mnnlwr 

 of i-*ll molccuK-s a " stt " in a'lUfinite direction. The cells tend to 

 erolve impulses more easily in one direction — that is (2), the mole- 

 cules tend to vibrate in n detinite direction. The motion at Inst 

 becomes automatic — almost purely retlex ; that is, an efferent im- 

 pake, which might (rive rise to many varied forms of efferent 

 impulses, has, by frwjuent renewal, come to bo ossociatcnl with a 

 certain definite efferent impulse. Examples may bo easily found of 



2. Intellectual memory, connected with the acquisition of know- 

 ledge, Ac. Bain says : '" Uenowed feeling occupies the very same 

 part, and in the same manner, as (he original feeling, and in no 

 other port, nor in any other manner that can be assigned. Again, ho 

 snpi>09es that a cell, once the sent of an impression, becomes s|)ecinlly 

 set apart for that impression, and for that only. I have not his book, 

 " Mind and Body," and cannot see the conto-vt at present ; but this, 

 according to the present fashion of explanation, seems to mo to 

 imply a " set " of the cell molecule, just as is believed to occur in 

 connection with physical memory — that is, in memory, ns a result 

 of some impression received, certain groups of brain cells have 

 developed a tendency for their molecules to vibrate in one direction 

 rather than in another. When motion is communicated to these 

 cells, it can only be in that definite direction ; it gives rise to cer- 

 tain changes (chemical), which form the recollection of the im- 

 pression, ond which may in some cases bo referred outwards from 

 the sensorinm to the end organs. There are several ways in which 

 recollections arise. We may again meet with an object which gives 

 rise to an impression we have experienced before. The impression 

 sets those cell molecules in motion with less effort than normal — wo 

 recollect the impressions. Again, recollection may arise volun- 

 tarily. Uow does this occur ? Again, involuntarily — impressions 

 which we cannot trace to any sensory impression directly or by the 

 association of ideas — i.e., the correlation of certoin groups of nerve 

 cells. 



Voluntary recollection does not seem to admit of explanation so far. 

 It is with involuntary recollection that I would connect Dr. Muir- 

 head's theory of apparitions. The formation of nn imjiression at 

 first originates an ether wave. This, if it should return to the 

 vicinity of the nerve-cells, might affect them, causing the molecules 

 to vibrate in the direction in which their motion has been deter- 

 mined. Uow this return is to occur, I don't see. An impression 

 of a like nature undergone by another brain would originate an 

 ether wave of the same nature, which, falling on brain-cells " duly 

 eensitive," would, as above, give rise to the special impression 

 connected with that ether wave. Two ether waves compounded 

 might originate an idea by the action of molecules of about the 

 same set. As to Mr. Knowles' friends, Damon and Pythias, may 

 I sugeest that the brains of two persons, who had been accustomed 

 to Ije under the inlluencc of the same impressions, mental and 

 physical, would thus, on the hyjKithesis given above, pass into 

 partial identity of condition as far as the molecular structure of 

 com-sponding brain-waves is concerned. I don't think it would be 

 too much to sny, on the hypothesis given nl«)vc, that such brains 

 wonld hove a considerable influence over one another. [Please 

 consider the two last f>aragraphs of the extract from Mr. Knowles 

 lo be inwrted here.j Atomic movements of inanimate objects 

 causing ether waves would cause the recollection of these same 

 objects. 



" Fools msh in where angels fear to tread." Jfay 1 ask, as to 

 your question to Dr. Muirheod, whether any special organ is neces- 

 sary for the apjireciotion of these ethoreol waves 'f The ether, 

 circumambient, all penetrating, passes also between the cells and 

 molecules of the central vertex. Jlay not the waves of this ether 

 act diretrtly on the ner>-c molecules I' As to how they act, even I am 

 not a wild enough speculator to venture a theory just now. When 

 asked to explain memory and such trifles, it is much pleasanter to 

 retreat under the sepia cloud of " molcculor action," "atomic 

 change," und «o weiter, than to confess our utter ignorance ; but 

 after all one fccU rather doubtful as to the amount of sntigfuction 

 afforded by the explanation. 



Edinburgh, Awj. 5, 1882. Dk. Joik. 



DRCXKEXXE8S. 



[656] — My experience is that drunkards live long, ond do not die 

 out sjiecdily. Their children suffer for the acts of their fathers, 

 and would no doubt die, only they generally decline to follow in the 

 steps tliat liave Virought them disgrace and misery, and so our race 

 berftm>-s weaker and wicker. [Is this really the case I' Aro vie nil 

 weaker tlian our grandfathers? — El>.] For in these artificial days 

 the weak live as well as the strong. Mattieu Williams's theory 

 might haro done for other ages, but it won't work now. 



Joiix Ale;i. Ollauij, F.U.M.8. 



[557] — The question of temperance societies and pledges is being 

 actively discussed in Knowi.kdok just now, but there is one rnisoii 

 d'i'tro for them which has not yet come nj) there. It is said to bo 

 a folly for a man wlu> does not feel the craving for drink, to gi»o 

 up, save for example, his enjoyment in a glass which does him no 

 harm. But surely, in the present state of society, many men aro 

 placed in positions where they aro iu constant danger, unless they 

 exercise much thought and 'system (and how few have these at 

 command !), of being led into habits of drinking. Men, I menu, 

 who frequent clubs, messes, and such places where wine and spirits 

 are always going, and "nips" constantly pressed ujicm them by 

 hospitable friends. Workmen, again, who have to go from house 

 to house, and get beer given them at each. Now, 1 think yon 

 would heartily commend such men for abstaining (if they found 

 alcohol did them little good) from playing with such nn edged tool, 

 just ns one commends a resolution "to abstain altogether from 

 gambling or betting. Facilis desccntus Avcrno is true of alcohol 

 above uU, and surely it is wise for young men at least to keep off 

 the slope. Temperance societies in both sertions have, I believe, 

 done far more good thus, by making men think, than by curing ni 

 few drunkards, but it, is a work that can obviously never be gauged. 

 W.BkVIL BlloWNE. 



[It appears to mo that men placed in such positions as our corre- 

 spondent mentions, should at least make the resolution never, 

 under any circumstances, to drink in public under the conditions 

 named ; but that need not render it necessary for them to refrain 

 from such moderate and regulated use of alcohol as they may find 

 wholesome and readily controllable. — En.] 



FKKGUSON'S MECHANICAL PARADO.X. 



[558] — I have never seen the book entitled " lUnmrkablo Men," 

 to which " CupiduB Cognoscore " refers in letter 522 (p. 219), and 

 am therefore ignorant in what way Ferguson's paradox is illustrated 

 there. As a matter of fact, it affords an examiilc of what is known 

 in mechanics as nn cpicyclic train. As usually constructed, a; 

 heavy base standing on the table supports a fixed toothed wheel, 

 on the axis carrying which, and beneath it, an arm goes roimd ; on 

 this arm aro two axes, one nenr its extremity carrying the thrco- 

 wheels of which your correspondent speaks, while the other carries 

 an " idle " Marlborough wheel to transmit the movement. Let u» 

 suppose that the fixed wheel has 60 teeth, the "idle wheel "any 

 number that is convenient, and the three thin wheels 61, 60, and 

 59 teeth respectively. Then it is pretty evident that when the- 

 arm is made to revolve round the fixed wheel, the wheel with the- 

 61 teeth will advance slowly in the same direction as the arm ; that 

 with 00 teeth will remain statioiuiry, and the wheel with 59 teeth 

 will go backwards. " C. C." will, of course, note that tho intro- 

 duction of tho intermediate or " idle " wheel, in no sense affects, 

 tho principle. 



A Fellow ok the Royal Astronomiial Society. 



SPOTS ON THE SUN. 



[559] — The date at which Mr. A. Green's (piery arrived in Juno, 

 and the very unfavourable weather which followed its reception, 

 prevented us from having tho sketch of tho sun-s|>ot made whicHr 



GROfP OF Sun-spots, Aixu.st 21, 1882 (10.|5 a.m.). 



he asked for. We, however, now append a eiirefnl drawing of 

 the Ijeautiful group which was ujxjn the solar disc at tlit date oi' 

 its execution, in hope that it may serve bis purpose. 



