4io 



THE POPULAR SCIENCE MONTHLY. 



electrical work spent upon it. The lat- 

 ter result is alone to the point, as in the 

 former the efficiency of the dynamo- 

 machine enters as an element, as well 

 as that of the storage-battery. On this 

 showing the storage-battery does not 

 seem to have reached a commercial 

 stage, but that it will do so at no very 

 remote time there is every warrant for 

 believing, when we consider the large 

 amount of attention there is now being 

 given to the subject, and the rapidity 

 with which electric appliances are at 

 present passing out of the experimental 

 into the industrial stage. 



LITERARY NOTICES; 



INTERNATIONAL SCIENTIFIC SERIES, 

 No. XLI. 



Diseases of Memory: An Essay in the 

 Positive Psychology. By Th. Ribot, 

 author of "Heredity: its Phenomena, 

 Laws, Causes, and Consequences," 

 " English Psychology," etc. Translated 

 from the French by William Hunting- 

 ton Smith. D. Appleton & Co. Pp. 

 209. Price, $1.50. 



From both a scientific and a practical 

 point of view this monograph is among the 

 most interesting and valuable that have ap- 

 peared in the " International Series." It is 

 an able statement of the latest knowledge 

 on a subject which concerns almost every- 

 body. "We can here only intimate the au- 

 thor's stand-point in the discussion. 



Where are our thoughts when we are not 

 thinking them ? Not a ten-thousandth part 

 of the great stock of mental acquisitions 

 which a man possesses is ever in con- 

 sciousness at any one time. And, of those 

 which in our waking states are ever rapidly 

 emerging and disappearing, only a very small 

 portion are obedient to the will they exist 

 and are preserved independently of con- 

 sciousness, and they come and go, to a large 

 extent, by laws deeper than volition. 



Where, then, is the great stock of our 

 ideas when we arc not aware of them ? The 

 common, the prc-scientific answer is, they 

 are in the mind, which is an abstract spirit- 

 ual container, of which we only know that 

 it is an immaterial essence. This mind is 



made up of faculties, and memory is one of 

 these faculties, in which the intellectual con- 

 tents are stored up until called for by volun- 

 tary thought. Hamilton speculated vaguely 

 about " mental latency," but where the men- 

 tal stock is kept was always regarded as 

 a great mystery in fact, an insoluble mys- 

 tery which there was no use in working at, 

 because all the mind that concerns us is the 

 mind we know about. Mind was thus bound- 

 ed by consciousness, and memory, or the re- 

 call of ideas, was considered purely as a 

 matter of volition, while this faculty in all 

 men was looked upon as very much the 

 same thing. Dugald Stewart, for example, 

 says of the memory, " that original dispari- 

 ties among men, in this respect, are by no 

 means so immense as they seem to be at 

 first view, and that much is to be ascribed 

 to different habits of attention, and to dif- 

 ference of selection among the various ob- 

 jects and events presented to their curi- 

 osity." 



Cut it is obvious enough that nothing 

 can be done with the problem of mental 

 disease under this view ; and, if we are to 

 inquire concerning "diseases of memory," 

 the first thing is to ascertain what we have 

 to deal with that is capable of being dis- 

 eased. This, of course, is the corporeal 

 part of our nature, and it implies at once 

 that memory has its organic side. It is the 

 nervous part that registers and conserves 

 our psychical acquisitions, and accordingly 

 Professor Ribot begins his work by the 

 study of nervous structures, properties, and 

 activities, and with the consideration of 

 memory as a biological fact. Memory im- 

 plies three things : first, an impression, and 

 therefore an organism capable of receiving 

 impressions. The various senses bring, and 

 the nervous centers receive and record, 

 these impressions. The centers, moreover, 

 recombine, reassociate, and elaborate these 

 impressions in the most complex ways. 

 This implies, secondly, a conserving or re- 

 taining capacity of the nerve-centers, which 

 answers to the notion of mental storing. 

 Then there is, thirdly, the emergence of 

 these impressions in thought, or conscious 

 recollection. This deliverance in conscious- 

 ness is a result which we might call inci- 

 dental, and depends, of course, on the prior 

 conditions of impressibility and -conserva- 



