P OP ULAR Ml 'S CELL ANY. 



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speaker had long been convinced of the cor- 

 rectness of this supposition, but it was only 

 recently that he had been able to make a 

 satisfactory demonstration of the principle. 



Visions of the Blind. — Mr. J. Jastrow 

 had an interesting paper, at the American 

 Association, on "The Dreams of the Blind." 

 Vision in dreams is connected with a recol- 

 lection of sight, and the fact of its mani- 

 festation would mean that in the dreamer's 

 brain there is developed a sight-center, the 

 spontaneous activity of which is the ma- 

 terial substratum of his dreams. Brain- 

 centers, we know from observation and ex- 

 periments on animals, are of slow growth. 

 By asking what is the latest age at which a 

 child may become totally blind and still re- 

 tain dream-vision, we will be asking how 

 long a time is necessary for the sight-center 

 to develop, and sufficiently to enable it to 

 function without further retinal stimulation. 

 " Two hundred blind persons (mostly young) 

 in the institutions for the blind at Balti- 

 more and Philadelphia, were questioned in 

 detail in regard to their dreams, and from 

 their answers I conclude that the critical age 

 is between the filth and the seventh year. 

 Those losing their sight before this age have 

 no more vision in their dreams than if they 

 were blind from birth. Those who become 

 blind during this period may or may not 

 lose dream-vision ; while those whose eye- 

 sight is destroyed after this period find 

 themselves quite on a par with seeing per- 

 sons in dream-life. Only cases of total 

 blindness are employed as a basis for this 

 conclusion. With regard to cases of partial 

 blindness it is found that the same period 

 divides those whose dream-vision is brighter 

 and more vivid than the partial sight of 

 waking life from those whose waking life 

 furnishes, though filled with imperfect sen- 

 sations of sight, the material for dream- 

 images." 



The Cause of the Charleston Earth- 

 quake. — The theories of the causes of earth- 

 quakes are almost as various as the phe- 

 nomena themselves ; and it is the general 

 opinion of those who have most carefully 

 studied the subject that no single cause is 

 competent to account for all that occur. The 

 most evident fact about the cause of the 

 recent shocks by which Charleston has been 



afflicted is, that there Is nothing volcanic 

 about it. Otherwise, our geologists incline 

 to the belief that they are the concomitant 

 of a line of weakness extending near the At- 

 lantic coast from about Troy, New York, by 

 Baltimore, Washington, and Richmond, to 

 the Carolinas, and that the phenomena were 

 immediately the result of a renewed fault- 

 ing or displacement in the latter region. 

 Tidal action may have had something to do 

 with it ; and notice has been taken of the 

 fact that at the time of the severe shock at 

 Charleston, the moon had been new, at peri- 

 gee only about sixty hours, or a fair time 

 for the accumulation of the effect, previous 

 to its occurrence. The fact particularly 

 illustrates Perrey's theory of tides of the 

 fluid interior of the earth. How little, how- 

 ever, is really known about the causes of 

 this or of any other earthquake is some- 

 what amusingly illustrated by a remark of 

 Professor Dawson's the day after he had 

 delivered his address as President of the 

 British Association, and after the news had 

 reached him of the disaster in Charleston. 

 " The phenomena of the present earthquake 

 convulsions in America and elsewhere, but 

 particularly in America," he said, " are ex- 

 tremely puzzling, and completely upset some 

 of the conclusions set forth in the address I 

 read last evening." The Geological Survey 

 has sent out a circular asking from observ- 

 ers as definite statements as they can obtain 

 respecting the details of the phenomena. 

 The questions have reference to the per- 

 ceptible occurrence of the shock ; its exact 

 hour, minute, and second in standard time ; 

 the duration of the shocks ; the accompa- 

 nying noise, if any ; the number, etc., of the 

 shocks ; the measure of intensity — whether 

 very light, light, moderate, strong, or severe ; 

 the possibility of the existence of any oth- 

 er cause for what happened than an earth- 

 quake ; and whatever other particulars of 

 interest may have been noticed or learned 

 by hearsay. 



Mr. Darwin on Geologic Time. — Mr. G. 



H. Darwin, President of the Geological Sec- 

 tion of the British Association, made a sur- 

 vey of the theories of geological time, in- 

 cluding those of Mr. Croll and Sir William 

 Thomson, and concluded from them that 

 something has been acquired to our knowl- 



