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THE POPULAR SCIENCE MONTHLY 



to make it into two volumes instead of one. 

 That which was the first part now appears 

 as a separate volume, confined to the physi- 

 ology of mind ; and will be followed by its 

 sequel, or companion-work, as a separate 

 treatise on mental pathology. It is an ex- 

 cellent thing on every account to divide the 

 original work in this way, for, although the 

 subjects are most intimately connected, they 

 can be just as well studied together now as 

 before, while there will unquestionably be 

 many who will care chiefly for but one of 

 the volumes. That now issued has an inter- 

 est for all students of the philosophy of 

 mind, while the one following will more 

 directly concern the medical profession. 

 " The Physiology of Mind " by Dr. Mauds- 

 ley is a very engaging volume to read, as it 

 is a fresh and vigorous statement of the 

 doctrines of a growing scientific school on 

 a subject of transcendent moment, and, be- 

 sides many new facts and important views 

 brought out in the text, is enriched by in- 

 structive notes and quotations from author- 

 itative writers upon physiology and psy- 

 chology, and by illustrative cases which 

 add materially to the interest of the book. 

 We have room for but one of these, show- 

 ing the manner in which the loss of one 

 sense is followed by an extension or in- 

 crease of function of those which remain : 



"Many years ago application was made to 

 Dr. Howe, of the Massachusetts Asylum for the 

 Blind, by a locksmith for the ' loan ' of a blind 

 boy, as he said, who had quick ears and a silent 

 mouth. On giving satisfactory answers he got 

 his loan. He wanted a boy to help him open a 

 new and complicated lock. An inventor exhib- 

 ited a locked safe and the key, saying that there 

 was money within, which should be given to 

 whoever could open the lock without deranging 

 it. The peculiarity of the lock was, that it had 

 ten bolts, which, from all that could be ascer- 

 tained, seemed exactly alike, but in reality one of 

 them was an inch longer than the others, so that, 

 when all were thrown forward, that one alone 

 held the door closed. The key would lift any 

 of the ten holts; hut in order to open the safe 

 it must be applied to the long bolt, and to that 

 only, and that one must he lifted and turned 

 back in order to open the lock; hut if any other 

 of the ten were lifted and turned back ever so 

 little, it deranged the combination, and the lock 

 could only be opened by a peculiar instrument. 

 The object, then, was to ascertain which of the 

 ten was thrown forward without turning back 

 any other one. 



" The mechanic lifted each bolt carefully with 

 the key, and lot it fall, but without trying to 

 throw it back; and he then tried to ascertain 



if in falling it made any peculiar noise ; for he 

 inferred that, as the only one which held the 

 door was an inch longer thau the others, it must 

 fall with a slightly greater force ; but the differ- 

 ence was too slight for his ear. He took the 

 blind lad, and asked him to listen carefully to 

 the sound which each bolt made as he lifted and 

 let it fall. Alter listening to each intently, the 

 lad said the sixth one struck a little the loudest. 

 The mechanic lifted and let each one fall care- 

 fully several times, and each time the boy in- 

 sisted that the sixth bolt sounded the loudest. 

 Upon this the mechanic lilted and turned back 

 the sixth, and the lock was opened without the 

 combination being deranged." 



No library of mental philosophy will be 

 complete without this book, and no liberal 

 student of the subject can refrain from giv- 

 ing it his serious and critical attention. 



A Practical Treatise on Lightning-Pro- 

 tection. By Henry W. Spang. 12mo. 

 Pp. 180. With Illustrations. Philadel- 

 phia : Claxton, Remsen & Haffelfinger. 

 1811. Price, $1.50. 



The above book contains the result of 

 the author's observation and study on the 

 subject of lightning-protection during an 

 eighteen years' experience in the telegraph- 

 business. After an introductory course of 

 experiment with artificial lightning, and an 

 explanation of the principal known facts 

 relating to the electricity of the earth and 

 atmosphere, the author proceeds to show 

 that few of the lightning-rods or conduct- 

 ors now erected can be relied upon for 

 an easy passage of heavy lightning-dis- 

 charges, and goes on to prove that the metal 

 roof and rain-pipes of a building can be 

 made a better protection at a reduced ex- 

 pense. Explicit directions then follow for 

 the protection of buildings of every descrip- 

 tion, ships, oil-tanks, steam-boilers, bridges, 

 telegraph-poles, etc. 



Notes upon the Lithology of the Adiron- 

 dack. By Albert R. Leeds. Pp. 35. 

 From the American Chemist. 



Prof. Leeds does not assume to present 

 a complete lithology of the Adirondack re 

 gion, but limits himself to giving an outline 

 of the work already done in that field : a 

 description of the rocks so far collected by 

 himself; analyses of some of the more im- 

 portant typical rocks and minerals ; results 

 of microscopic study of rock-sections ; and, 

 finally, inferences drawn from these prem- 

 ises. 



