2l8 



SCIENCE. 



[Vol. XVI. No. 402 



SCIENCE: 



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Vol. XVI. 



NEW Yj 



:gKK, 



October 17, 1890. 



No. 402. 



CONTENTS: 



Plans and Work at Clark Uni- 

 versity 211 



The Aryan Cradle-Land 



J. S. Stuart Glennie 214 



Ethkr Intoxication 214 



Health Matters. 



Leprosy in Spain 215 



Cremation at Milan 215 



Child Suicides 215 



Malarious Africa 215 



Hairs as Records of Emotional 



Disturbances 216 



Notes and News 216 



I Letters to the Editor. 



Espy's Experiments 

 I H. A. Bazen 218 



Deaf-Mutes and their Instruction 



B. Engelsman 218 

 Another Magnetic Man 



E. W. Hall 221 

 Book-Reviews. 

 Erster N.achtrag zur Biblio- 

 graphie des Modemen Hypnot- 



ismus 221 



Guyot's Earth and Man 221 



A Digest of English and Ameri- 

 can Literature ... 222 



Among the Pdblishers 222 



been to determine the sufficiency of Espy's experiments in estab- 

 lishing the view that there is an uprush of air in our storms, 

 which is increased by the liberation of latent heat from condensa- 

 tion, etc. It seems to me that if all other views regardin>< his re 

 searches prove faulty, the single fact that he used an expansion 

 which was equivalent at times to a rush of air at ten thousand 

 feet per second, — an absolutely incredible velocity for our up- 

 rushes, — would be well-nigh fatal to his deductions. In repeating 

 Espy's work, I simply attempted to carry on a research which 

 should in some measure be comparable with natural phenomena. 

 Expansions at the rate of five hundred and a thousand feet per 

 second are certainly far greater than any that we can consider as 

 occurring in our storms. I hope shortly to repeat my experiments 

 vrith improved apparatus, and determine, if possible, a few points 

 in Espy's work that are not quite plain. Professor Ferrel himself 

 shows that these very researches of Espy were faulty, and this 

 corroborates in some measure my results. 



Finally, Professor Ferrel calls attention to the deduction that I 

 have made, that compressing air ten inches, without the loss of 

 lieat, would heat it 163°, and gives 43" as the true temperature. 

 My deduction was based upon the facts presented by Professor 

 Tyndall on the sixty-sixth page of "Heat as a Mode of Motion." 

 I find I have mistaken Tyndall's meaning. This computation 

 does not seem very simple One of my friends, a physicist, gives 

 me a very different value from Professor Ferrel's. The simplest 

 computation would be in the case of a cooling after a compression, 

 and after the compressed air has attained the outside temperature. 

 I feel sure, that, if Professor Ferrel will make that computation, 

 he will see at once that his temperature of 45° cannot be correct. 

 The problem seems quite complex, and I would be very glad to 

 have some one familiar with such problems work out a solution. 

 The problem is this : What will be the rise in temperature in a 

 mass of air at atmospheric pressure if its pressure is increased 

 without the loss of any heat: the increase of ten inches to be con- 

 sidered afler the air has cooled to its initial temperature? May f 

 call Professor Ferrel's attention to a single point which he seems 

 to have overlooked, or regarded of little importance? It is this: 

 if we consider that Espy, after compressing the air, waited until 

 it attained the outside temperature before explosion, the resultant 

 cooling after expansion cannot be compared in any way directly 

 with the heating produced by compression and without the loss 

 of heat. Moreover, it is impossible to determine, by Espy's work, 

 the amount of the previous heating, from the cooling after explo- 

 sion. H. A. Hazen. 



Washington, Oct. 4. 



LETTERS TO THE EDITOR. 



*#* Correspondents are requested to be as brief as^possible. TIte writer^s name 

 is in all cases required a^ proof of good faith. 



The editor will be glad to publish any queries consonant with the character 

 of the journal. 



On request, twenty copies of the number containing his communication mill 

 be furnished free to any cor>-espondent. 



Espy's Experiments. 



Professor Ferrel's letter in Science of Oct. 3 emphasizes some 

 of the points that I have insisted upon in regard to the distinction 

 which should be made between meteorologic facts and theories. 

 Professor Ferrel clearly sets forth the fact that such theories de- 

 pend upon "physical constants," such as "the mechanical equiva- 

 lent of a unit of heat, the specific heat of air, the latent heat of 

 aqueous vapor, the tension of the aqueous vapor of saturated air 

 at any given temperature," etc. I have tried to show that start- 

 ing from such facts, and elaborating a theory which shall account 

 for such complex motions as we meet with in our storms, is cer- 

 tainly very interesting; we do not agree, however, as to whether 

 it is profitable or not. That the results of Espy's experiments do 

 not enter into modern theories wiU be a surprise to some, I think. 

 I have tried to show that no one, so far as I knew, had tried Espy's 

 experiments or shown that they could be applied to storm condi- 

 tions as they are now familiar to us. Of course, a score of physi- 

 cists, more or less, liave theorized upon the subject. 



May I suggest that I have never contended that latent heat is 

 not set free on condensation of moisture? My whole effort has 



Deaf-Mutes and their Instruction. 



By a deaf mute is understood one who is born deaf, or lost his 

 hearing before the acquisition of speech, and in consequence 

 thereof is mute. Deafness may be divided into two classes; viz., 

 congenital and acquired. Acquired deafness admits of four sub- 

 divisions: — 



A. Where hearing has been lost before the acquisition of 

 speech. 



B. Where vowel hearing alone is retained. 



C. Where the hearing has been lost after the acquisition of 

 speech, but the latter imperfectly retained. 



D. Where the hearing has leen lost and speech retained, but 

 the individual lacking education, and precluded from training in 

 common with hearing children. 



Those described under C and Z>are designated as "semi-mutes." 

 Over fifty per cent of the total number of deaf-mutes are of the 

 acquired form. Children who lose their hearing at the age of 

 three or four years are apt to forget speech within about a year's 

 time, unless intelligent parents endeavor to retain and cultivate 

 it. The hearing is more essential to intellectual development and 

 enjoyment than any other sense. Without education, a deaf-mute 

 is entirely debarred from the acquisition of spoken language, the 

 noblest product of the mind. It is true, necessity, the mother of 

 invention, impels one thus affected to invent a language of natural 

 signs to communicate with his fellow beings; but he is not en- 

 abled to express or receive abstract ideas tlirough this medium. 



