Nov. 19, 1S74] 



NA TV RE 



45 



and independently of, ihe actual series of feelings making 

 up its own individual life." To follow this from the idealist's 

 point of view is quite beyond us. A belief in permanent 

 possibilities of sensation that flow on independently of 

 our feelings is in some danger of being mistaken for 

 realism. iVIr. Sully, however, is very sure that the realists 

 are wrong ; and as a psychologist he must be able, by aid 

 of his science, to explain their error, just as an astronomer 

 accounts for an eclipse. This is how our realistic philo- 

 sophers go wrong. Under the influence of a refined 

 sentiment of awe, they see what is not there. Not only 

 does this emotion "lead the mind to anticipate the 

 presence of insoluble mystery where a calmer intellectual 

 vision sees only clear regulaiity, but it serves to support 

 conceptions of an unknowable where tlie closest obser- 

 vation and most accurate reasoning fail to detect any 

 signs of such an existence." The superstitious terror of 

 the rustic transforms a white calf into a ghost ; the awe of 

 the philosopher sees a ghost where there is no calf. 



In a very suggestive essay Mr. Sully handles the 

 difficult subject of "Belief: its Varieties and its Condi- 

 tions." He finds "the primitive germ of all belief, the 

 earliest discoverable condition that precedes in its in- 

 fluence that of action, in the transition from a sensation 

 to an idea." In thus attempting to understand how the 

 state of mind called behef resembles, differs from, and is 

 related to other states of consciousness, Mr. Sully is, we 

 think, on the right track. He is, however, by no means 

 free from the crude, popular notion, that belief and 

 volition, considered as facts of consciousness, have some 

 special causal connection with the bodily movements. 

 Indeed, he thinks that Prof Bain "has succeeded mcst 

 completely in showing the will to be a secondary and 

 composite state of mind, inferable from more rudi- 

 mentary states," one of these so-called rudimentary states 

 bcirg spontaneous_bodily movements, which occurring by 

 " a coincidence purely accidental " along with states of 

 consciousness, these unlike things get somehow stuck 

 together by " an adhesive growth, through which the 

 feeling can afterwards command the movement." We 

 have repeatedly maintained that while on the one hand 

 there are reasons which seem to compel the belief that 

 on liis physical side man is a machine whose movements 

 can never escape by a hair's breadth from the inexorable 

 rule of physical law, there is on the other hand no " better 

 ground for the popular opinion that voluntary movements 

 take their rise in feeling and are guided by intellect, than 

 a superficial observer ignorant of the construction of the 

 steam-engine might have for a belief that the movements 

 of a locomotive take their rise in noise and are guided by 

 smoke."* That Prof Huxley's bold advocacy of this 

 view at the recent meeting of the British Association has 

 not called out more angry criticism is surely a most 

 hopeful sign of the times. 



It is with regret that we must now take leave of lliis 

 collection of essays, which we have reael with pleasure 

 and profit ; and we hope that our mode of expressing 

 our criticisms will not be misunderstood or supposed to 

 indicate a want of appreciation. To touch on all the 

 points we had marked for observatioYi would more than 

 double the length of this review. Especially do we regret 

 not being able to say a few words about " The /Esthetic 



* Nature, vol. ix. p. 17.^, : "The Relation of Body .ind Mind." 



Aspects of Character." If Mr. Sully could admit that 

 conduct cannot be beautiful in so far as it involves 

 struggle, mental effort, for example, in so far as it is 

 moral or virtuous on the subjective side, very little 

 would then stand between him and one commandino- 

 generalisation. Douglas A. Spalding 



LETTERS TO THE EDITOR 



[The Editor docs not hold himself responsible for opinions exfrcssed 

 by his correspondents. Neither can he undertake to return, 

 or to correspond -with the writers of, rejected fiianiiscripts. 

 No notice is taken of anonymous coinntunications.'\ 



Sounding and Sensitive Flames * 



II. 



Another example of a highly sensitive flame was recemly 

 described to me which seems to show that air-currents 

 flowing through gauze at a proper speed are sensitive without tl:e 

 intervention or simultaneous superaddition of a flame. A special 

 kind of Bunsen burner was made with a spiral mixino- tube 

 coiled in an inverted cup, at the centre of which is a small chamber 

 covered with wire-gauze at the foot of a short tube orflarae-p-pe. 

 The gas is admitted by a single jet passing through a cap of wne- 

 gauze covering the conical opening of the spiral tube, the object 

 of this cap of gauze being to distribute the air in its approach, and 

 to protect the gas-jet from ignition. The gas-flame burns with a 

 small bright green cone, surmounted by a larger envelope of pale 

 reddish flame, and it is intensely hot. Tlie green cone indi- 

 cates combustion of the most complete explosive mixture of air 

 and coal-gas, and when the burner is properly adjusted it can 

 only burn on the top of the flame-tube, where it finds the addi- 

 tional required supply of oxygen ; but it descends to the wire- 

 gauze at the foot of the tube if the air-sapply exceeds, or the gas 

 supply falls short of the right proportion. Iir some of these burners 

 the slightest noise of the kind that commonly affects sensitive 

 flanaes causes the cone of green flame to retreat into the tube and 

 settle on the wire-gauze at its foot, whence it rises aeain imme- 

 diately to the top of the tube, when the sound ceases. The expla- 

 nation seems to be that the air-current entering the mixing-tube 

 through the outer gauze cap is in a sensitive condition, and that 

 when thrown into disturbance by the external sounds, it is more 

 quickly seized and is drawn into the mixing-tube more rapidly 

 by the gas-jet than when it is flowing over the jet in a tranquil 

 state. The inventor of these burners, Mr. Wallace, assures me 

 that some of them exhibit the most sensitive of sensitive flames, 

 and that he has more than once thought of sending one of them 

 as a most singularly effective illustration of such flames to Prof. 

 Tyndall. 



The explanation here given of the sensitiveness of Wallace's 

 Bunsen-flame appears to be in great part correct ; but 

 the behaviour of the flame, which by Mr. Wallace's kindness 

 I have seen since the above was written, differs consider- 

 ably from that described ; and some experiments connected 

 with it lead me to modify to some extent the foregoing- 

 theory of the origin of sensitiveness in wire-gauze flames, 

 and even, apparently, to except the gauze itself from any 

 cmsiderable share of mechanital action in the piocess. The gns 

 in this burner is first turned low, until the green cone at the 

 centre nearly disappears, and merges into the outer border of the 

 flame from less effective mixture of air with the gas at a low 

 speed of the jet. The flame is now sensitive to the smallest 

 sound, mounting fully one-half hij^her at every word, or even 

 syllable of a speaker, and at the stroke of a bell, or other .acute 

 sound, reaching about twice its ordinary height. It undergoes at 

 the same time no change in its appearance, showing that the 

 contents of the mixing-tube and chamber are merely urged out 

 of the flame-tube with greater speed by some forward impulse cf 

 the jei. behind. If the sound is continued, as by constantly 

 ringing a bell, the expanded flame gradually subsides, from the 

 expulsion of all the inferior gas-mixture in the burner, reaches its 

 first stature, and passes into a condition of moie concentrated 

 combustion corresponding to a fuller, and therefore more rapid 

 admission of gas to the jet ; wlieir the sound ceases, the con- 

 tracted flame gradually recovers its fiist size and difluscness from 

 the same cause, namely, the expulsion of all the «'ell-ai;rated gas 



" CV'iitiiiited from p 6. 



