January 24, 1890.] 



SCIENCE. 



63 



— A. L. Burt has issued a volume on " Fugitive Facts," edited 

 by Robert Thome. It comprises short articles, alphabetically ar- 

 ranged, on topics constantly arising in conversation and general 

 reading, on which it is hard to find accurate and definite informa- 

 tion. The queries in the correspondence departments of periodi- 

 cals and newspapers have suggested many of the subjects treated. 

 The editor has added an appendix, devoted to short selections of 

 constantly used medical terms and short dictionaries of mythology 

 and music. 



— G.P.Putnam's Sons will publish shortly a. new volume, in 

 The Story of the Nations Series, entitled " The Story of the Bar- 

 bary Corsairs," by Stanley Lane Poole, with the collaboration of 

 Lieut. J. D. Jerrold Kelley of the United States Navy ; and two 

 new books in The Questions of the Day, on " Railway Secrecy," 

 by John M. Bonham, and "American Farms," by J. R. Elliot. 



— The December number of the Riverside Literature Series 

 (published quarterly during the school year 1889-90 at 15 cents a 

 number, by Houghton, Mifflin, & Co., Boston) contains " Waste Not, 

 Want Not, and The Barring Out," from Maria Edgeworth's " Parent's 

 Assistant." The great popularity which the " Parent's Assistant " 

 has had, ever since its publication in 1822, has induced the publish- 

 ers to include some of the stories from this book in the'Riverside 

 Literature Series. The stories selected are interesting and simple : 

 the lessons which they inculcate are the advantage of frugality and 

 the disadvantage of a blind party spirit. The same publishers an- 

 nounce that they have in press for early publication a book by John 

 Fiske on civil government. This book treats in a simple way of 

 the government of towns, cities, states, and the nation, and will be 

 a most valuable book for schools and families. 



— Andrew D. White will resume his " New Chapters in the War- 

 fare of Science " in the February Popular Science Monthly. The 

 forthcoming chapter will be on " Comparative Mythology." It deals 

 with the myths invented to explain strangely shaped or distributed 

 rocks, taking the story of Lot's wife, which has gone through 

 many curious variations, as a special example. " The Localization 

 of Industries" is the subject of an article by J. J. Menzles, to ap- 

 pear in the February number, which will throw light on the most 

 important problem before Congress this winter. It tells what les- 

 sons science draws from the course of industrial evolution in regard 

 to encouraging the establishment of industries in a country. A 

 searching examination of Henry George's taxation doctrine, by 

 Horace White, will appear under the title, " Agriculture and the 

 Single Tax." Mr. White maintains that the interdependence of all 

 industries disposes of the claim that agriculture has enough ad- 

 vantage over other occupations to warrant laying the burden of all 

 taxation upon it, and he asks whether the scheme of " economic 

 rent " would include paying a bounty to farmers whose profits are 

 a minus quantity. A second instalment of " Letters on the Land 

 Question," from, Huxley, Spencer, and others, including an espe- 

 cially able review of the question by Auberon Herbert, will be 

 printed. 



— Fords, Howard, & Hulberi have .published a small volume by 

 Martin W. Cooke on " The Human Mystery in Hamlet," the ob- 

 ject of which is to present a new view of the character of Hamlet 

 himself. The theories of Hamlet's character that critics have here- 

 tofore advanced are many and various, but Mr. Cooke's theory is 

 quite different from them all. He holds that the dramatist's object 

 in exhibiting the career of Hamlet was to portray " the conflict be- 

 tween his will and his passions, . . . the strife between the higher 

 forces of the being and the lower." Or, as he elsewhere expresses 

 it, " the theme of Hamlet is the interior life of humanity in this 

 world, striving to harmonize its actions with a supernaturally im- 

 posed law of rectitude, which it recognizes but ever fails to fulfil." 

 Now, we confess that this theory is less satisfactory to us than any 

 of its predecessors, for we cannot see the least indication of a 

 moral conflict in Hamlet's action or conversation — mdeed, we 

 should say that the moral element was conspicuously absent ; nor 

 can we see the propriety of calling the command of a ghost " a 

 supernaturally imposed law of rectitude." Students of Shak- 

 speare will take an interest in reading Mr. Cooke's work, but we 

 doubt if they will agree with its conclusions. 



LETTERS TO THE EDITOR. 



*,'Corres/ionds7its are requested to be as brief as iossibte. The writer's name is 

 in allcascs required as proof of good faith. 



The editor luill be glad to publish any queries consonant -with the character of 

 the journal. 



Physical Fields. 



Professor Dolbear's interesting article on "Physical Fields," 

 that appeared in your issue of Dec. 27, was called to my notice, 

 and I have read it with considerable attention. It seems to me 

 that he is entirely wrong in some of his premises, and that his 

 conclusions are therefore, some of them, untenable. With your 

 permission, I will point out where I differ with him. 



His use of the term "stress" is certainly not correct. He says, 

 under the head of " The Electric Field," " The phenomena are 

 explained as due to the-stress into which the neighboring ether is 

 thrown by the electrified body. . . . Experiment shows that this 

 kind of a stress travels outwards with the velocity of 186,000 miles 

 a second, or the same as that of light." 



It does not seem to me to be proper to say that a stress travels : 

 it rather exists. In this particular case he is referring to the phe- 

 nomenon of electrification, which is a static effect or condition. As 

 I understand Maxwell, and Hertz and Thompson and Lodge, they 

 do not any of them believe that electrification involves motion in 

 any way whatever. It is a condition which is dual in its character. 

 The negative exists because of the existence of the positive, not be- 

 cause of propagation from one to another. They also believe that 

 one cannot exist without the other : .the very existence of one, 

 therefore, involves the existence of the other. The element of time, 

 and therefore of rate of propagation, must be eliminated entirely. 



What he does mean is, that an impulse due to the yielding to 

 this stress is propagated, etc. 



Again he says, " If this assumed electrified mass of matter were 

 the only matter in the universe, any electric change in the mass 

 would ultimately re-act upon the whole of space, and be uniform 

 in every direction." This statement involves a contradiction of 

 terms, for how can we have a condition of stress that is uniform 

 throughout all space .' It is certainly true that under static con- 

 ditions, or under conditions of stress generally, where there are 

 two bodies or more concerned, the field is distorted by their mutual 

 re-action (that constitutes the stress) ; but I maintain that where 

 there is but a single body in space, there can be no such thing as 

 stress in that space outside of the body itself. If the body in ques- 

 tion be but a mathematical point, there can be no stress at all. 

 There can be no tension on a cord that is perfectly free to move. 



The same criticism is made upon his remarks under the head of 

 "The Magnetic Field." In the case of the magnet the justice of 

 my criticism will be, perhaps, more apparent. Were it possible to 

 conceive of a magnetic particle with but a single pole, could we 

 imagine that pole surrounded by a magnetic field? Our concep- 

 tion of the ultimate particle of magnetic matter endows it with two 

 parts, which re-act upon each other. If there were but a single 

 particle of magnetic matter in space, the "lines of force'' would 

 form closed curves within that particle, passing from pole to pole : 

 they could not, without violating all the laws of stress, radiate off 

 into space, as he says they would. 



Under the third head, " The Thermal Field," we come to a 

 very different class of phenomena. Here, as in the case of light, 

 we have vibration : we have distinctively a condition of motion of 

 the ethereal medium. We have passed from a state of rest, — a 

 static condition, — a state of potential, to one of movement, — a 

 kinetic condition. 



He says, " A hot body has a field, as well as an electrified or a 

 magnetized body : " so it has, but his fundamental and fatal error 

 is in not being able to discriminate between the two kinds of field. 

 The magnetic, the electric, and we may add the field of the force 

 of gravity, are purely static, purely potential, whereas the luminous 

 and thermal fields are kinetic. In the former there can be no 

 propagation, as the element of motion is entirely wanting. Add to 

 these fields of stress the element of motion, and they at once be- 

 come kinetic, and will then obey the laws of kinetic fields. 



A potential field without motion will exist forever : a kinetic field 

 requires the continual addition of energy for its maintenance. 

 Move a magnet, or the earth relatively to any other magnet or 

 body, and kinetic fields are produced. Move an electrified body. 



