356 



SCIENCE. 



[Vol. XV. No. 384 



physical principles; it has been abundantly tested by experi- 

 ment, both on a small scale in the laboratory, and, as we 

 may say, on a large scale in nature; it is universally ac- 

 cepted by men eminent in physical study, whose original 

 ability and careful, studious work have led them to be re- 

 garded as authorities in their science, but who, being au- 

 thorities, have not thereby become arbitrary and irrational. 

 It is therefore difficult to understand why the question 

 should be so confused by Hazen in the American Meteoro- 

 logical Journal, September, 1889." 



We have already seen that these so-called authorities have 

 tried no personal experiments, — at least, Ferrel does not al- 

 lude to any such experiments, — and have been entirely mis- 

 led by a few crude and contradictory researches. Is it not 

 high time that this appeal to authorities be done away with? 

 One of the main arguments advanced in support of storm 

 theories is that such men as Ferrel, Hann, Mohn, and a 

 host of others, are agreed, — agreed, however, as we have 

 seen, upon exceedingly unsatisfactory evidence. Professor 

 Davis suggests that these theories rest upon experiments, 

 "as we may say, db a large scale in nature." This certainly 

 is far from the truth. All the reasoning regarding the 

 diminution of temperature in dry and moist air as we ascend 

 in the atmosphere is founded upon purely theoretical con- 

 siderations. Every expei-iment, whether in the laboratory 

 or in nature, has provfd that these theories, in their sum 

 and substance, are false. Bnt there is no use in arguing 

 this question. I am so confident of my position in this con- 

 troversy, and have become so deeply interested in studies 

 regarding it, that I propose risking a little money upon it. 



I will give a hundred dollars to the first physicist who 

 will show that Espy's observations and experiments with 

 the nephelescope, as published in his "Philosophy of 

 Storms." giving the effects of expansion in moist and dry 

 air, when properly interpreted, prove his theory. 



It will be necessary to show, — 



1. That the rise of mercury in the gauge after expansion 

 was entirely due to heat from outside. 



2. That the speed of expansion Espy used, or the amount 

 of cooling from expansion, was comparable to the probable 

 speed of expansion in the free air. 



3. That by placing water in the bottom of the nephele- 

 scope the air would be saturated. 



4. That air, under the conditions observed by Espy, will 

 lose its dew-point or become unsaturated to the extent of 

 four or five degrees in twenty hours. 



5. That the cloud Espy observed was not largely formed 

 by dust pumped into partly dry air. 



6. How, if the heat liberated on condensation of the 

 moisture is used in performing the work of expansion, there 

 can be any heat from that source for expanding the air. 



7. Why, if there is any latent heat set free on condensa- 

 tion in saturated air, it would not at once re-evaporate the 

 condensed moisture, or heat the surrounding air to an unsat- 

 urated state. 



8. That if latent heat is set free on the formation of a 

 cloud in the nephelescope, its effect does not disappear at 

 the moment the cloud disappears, provided none of the moist- 

 ure settles to the bottom or sides of the nephelescope. 



9. By means of delicate thermometers, that there is not 

 practically the same effect upon the air, as regards heat, in 



expansions like these, whether we use dry or moist air, or, 

 what is the same thing, disprove the experiments and state- 

 ments made in the American Meteorological Journal, Sep- 

 tember, 1889. 



[Continued on p. 358.] 



MENTAL SCIENCE. 

 Motor Hallucinations.' 



The hallucinations most frequently recognized are those of 

 sight and hearing. Something is seen that has no objective ex- 

 istence, or something is heard when no sound is made. There is, 

 however, another form of hallucination to which attention has 

 been directed. In the hallucinations connected with language, all 

 these varieties are evident. Imaginary words are seen or heard, 

 and they may also be felt as movements. One patient, subject to 

 all kinds of hallucinations, perceived internal voices compelling 

 her to do and say things against her will ; but there was no sound 

 emitted, and the patient perceived the sense of the words by the 

 movements impressed upon her tongue. Several other cases have 

 been reported in which messages are received, not by sight or 

 hearing, but by the feeling of movements in the articulatory 

 apparatus. In one case this was unaccompanied by any other 

 mental defect, so that it was a pure case of verbal hallucination 

 of this motor type. This hallucination has its seat probably in the 

 third frontal convolution, the same part that is affected when 

 motor aphasia sets in, — a condition in which the patient is able 

 to understand written and spoken words, but is unable to give 

 expression to his thoughts for lack of the association between the 

 words and the motor feelings in the organs where those words are 

 to be formed. The hallucination thus arising may be of various 

 degrees of cogency : it may be entirely sensory, or there may be 

 slight movements of the articulatory apparatus, or there may be. 

 an irresistible tendency to speak the words that are imparted to 

 the tongue. Moreover, there sometimes occurs the hallucination 

 that the patient is speaking, and yet he utters no word. Here 

 there is in part an auditory hallucination, but also in part a motor 

 one; for the patient has the feeling of having made the movements 

 necessary for speaking the words. 



While the special development of speech makes the motor hallu- 

 cinations of speech unusually prominent, they are by no means 

 limited to this type, but may occur in any field of motor action. 

 While sleeping, we often have the feeling of going through fatigu- 

 ing and complicated motions, when in reality no movement takes 

 place. This is likewise to be referred to a stimulation of these 

 cortical centres. Similarly we dream of falling down a precipice 

 or of flying, — hallucinations equally frequent in insanity. It is-. 

 not unlikely that this was the basis of the flights through the air- 

 of the witches and those possessed. A special class of these sen- 

 sations arising from the stimulation of a central organ is to be 

 found in cases of amputation. It is well known, that, when an 

 arm or a leg has been lost, the person still retains all the feelings 

 of the lost member. The hallucination is at times so definite that 

 the clinching of the separate fingers may be felt, though the arm 

 and hand have been gone for years. Out of ninety cases, there- 

 were oidy four who did not describe these hallucinatory sensa- 

 tions. While these hallucinations are in part sensory, there are 

 also motor. Some feel the movements in the absent hand, de- 

 scribing its position as in the act of grasping, of writing, and so 

 on. The seat of these sensations is doubtless in the brain and in 

 those portions from which the innervation impulses arose when 

 the limb was intact. 



With regard to the genesis of the hallucinations, we seem war- 

 ranted in assuming three stages in their formation. The first is 

 central, and consists in forming a sensory image of the move- 

 ment; the second is centrifugal, and consists of an impulse from? 

 the centre to the muscles and nerves; the third is centripetal,, 

 indicating that the peripheral organs of locomotion have under- 

 gone the changes due to the movement. That the last stage is 

 not necessary to the production of the motor hallucination is. 

 sho'ivn in the case of the amputated liaibs and elsewhere. We 

 * M. Tamburiai, in Revue Scientifique, May 10, 1890. 



