250 



SCIENCE. 



[Vol. XV. No. 376 



Litchfield. This book tells in a simple way the story of the 

 old Norse gods, and is calculated to awaken an interest in 

 the religion of our Teutonic ancestors. It is based chiefly upon 

 the Eddas. The introductory chapter gives a clear idea of the 

 relative position of the "Nine Worlds" of the mythology, and 

 tells in a few words the relation of the gods and giants to ob- 

 jects in nature. The book is suited to children of any age, and 

 will possess equal interest for general readers. 



— Longmans, Green, & Co. will shortly publish, both in 

 London and New York, "The House of the Wolf," a 

 romance by Stanley J. Weyman. It tells the perils and 

 bravery of three young brothers in the fortnight before and 

 after the massacre of St. Bartholomevt's Day. 



— Messrs. Ginn & Co. announce to be ready in May or June 

 "Elements of the Calculus: Method of Bates," by A. 8. 

 Hardy, professor of mathematics in Dartmouth College. This 

 text-book is based upon the method of rates. The object of the 

 differential calculus is the measurement and comparison of rates 

 of cliange when the change is not uniform. Whether a quantity 

 is or is not changing uniformly, however, its rate at any 

 instant is determined es?entially in the same manner: viz., by 

 letting it change at the rate it had at the instant in question, 

 and observing what this change is. It is this change which 

 the calculus enables us to determine, however complicated the 

 law of variation maybe. From the author's experience in pre- 

 senting the calculus to beginners, the method of rates gives the 

 student a more intelligent, that is. a less mechanical, grasp of 

 the problems within its scope than any other. No comparison 

 has been made between this method aod those of limits and of 

 infinitesimals. This larger view of the calculus is for special or 

 advanced students, for which this work is not intended ; the 

 space and time which would be required by such general com- 

 parison being devoted to the applications of the method 

 adopted. 



— The February number (No. 4.5) of the Riverside Literature 

 Series (published quarterly during the school year 1888-90 at 

 1.5 cents a single number, by Houghton, MifHin, & Co., Boston) 

 contains "The Lays of Ancient Bome, " by Thomas Babington 

 Macaulay, with the author's introductions and historical notes. 

 The old Latin literature of the Romans had entirely disap- 

 peared, and the stories and legends about the early history of 

 Rome were incorporated into the writings of the later historians 

 without any written authority for them. These "Lays of 

 Ancient Rome" were writtn by Macaulay as an atteuipt to 

 show how these legends and stories about the early history of 

 Rome would have been sung by the old ballad-mongers, as they 

 wandered from village to village, and repeated to an eager 

 crowd of listeners these old songs which all knew so well and 

 yet always loved to hear. The lays have always been liked 

 by children on account of their life, movement, and romantic 

 incidents, and in this new form the publishers hope that they 

 will gain a still greater and more widespread popularity. 



— Tlie University of Pennsylvania has published a translation 

 of "The Federal Constitution of Switzerland," by Professor 

 Edmund J. James. The Constitution of Germany had previ- 

 ously been.issued in the same series, so that American political 

 students now have the means of comparing those two important 

 federal governments with our own. The principal difference 

 between the Swiss Constitution and ours is in the executive 

 authority, which in Switzerland is vested in a Federal Council 

 of seven members chosen by the two houses of the national 

 legislature. All executive orders are issued in the name of the 

 council, and, though there is a president of the council, he is 

 nothing but a moderator, with no more authority or dignity 

 than any other member. The present Constitution went into 

 effect in May, 1874, and gives to the central government much 

 greater authority than it had before. Nevertheless, there are 

 strong local and democratic elements in ihe government still, 

 as a perusal of this pamphlet will show. 



— Professor John Fiske will open The Popular Science Monthly 

 for May with an account of the life of Edward L. Youmans, 



including the story of his association with Herbert Spencer. 

 Professor Fiske was a warm friend of the late Professor You- 

 mans, and describes his fruitful labors in popularizing science 

 and the evolution philosophy in America with sympathetic 

 appreciation. Herbert Spencer has decided to publish the- 

 opening chapters of one of the uncompleted parts of his system 

 of philosophy, dealing with morality. Three of these chapters, 

 treating respectively of "Animal Ethics," "Sub-human Jus- 

 tice," and "Human Justice," will be printed in the same 

 number under the general title "On Justice." "Sumptuary 

 Laws and their Social Influence" will be discussed Iby Dr. 

 William A. Hammond. Dr. Hammond shows the absurd fail- 

 ures of laws against fine dress, costly food, and smoking, in 

 Rome, France, Turkey, and England, and against the selling- 

 and drinking of alcoholic liquors in some of the United States. 

 A careful comparison of secondary school programmes, French 

 and American, will also appear in the May number. The 

 author, Mr. George W. Beaman, maintains, that, if our high 

 and preparatory schools are to compare well with those of 

 France, the pupils must not only do more work, but they 

 must also work on more distinctly specialized lines. 



LETTERS TO THE EDITOR. 

 Anemometry. 



It is generally known that quite recently there have been 

 two independent series of investigations of the relation of cup 

 motion in the Robinson anemometer to wind travel, — the one 

 in England, with an arm twenty-nine feet long, upon which 

 the anemometer was whirled in the open air; and the other in 

 this country, with arms of twenty-eight and thirty-five feet 

 and used in a large closed court. It has been charged that the 

 experiments in this country were- modelled after those io 

 England; but this is not the fact, for the experiments in 

 Washington were nearly completed before a word had come 

 over regarding the otliers. A good proof of this is found in 

 the fact that Professor Marvin was so successful in refining^ 

 the apparatus and in using electrical contacts, that it required 

 only a few hours to show that no experiments of value could 

 be tried in the open air, while this has teen learned in England 

 only after many months. In the January number of the 

 Quarierly Journal of the Royal Meteorological Society there has; 

 appeared a second series of experiments tried in England, 

 which are quite interesting and in many respects novel. 



The earlier results showed that at low velocities there were 

 very great irregularities, though these practically disappeared 

 at fifteen miles per hour. In the open air the free wind would 

 undoubtedly equal a slow motion of the whirler; and as has 

 been shown, under these conditions, the factor would be made 

 twenty-five per cent too small. If we add to this the effect of 

 irregularities from whirls in the air and in the experiments, 

 nearly all the difficulty would be accounted for. 



To account for tliese irregularities, it has been suggested that 

 in the open air the more or less intermittent action of the wind 

 would tend to continually accelerate or retard the cups; and, 

 since they have a momentum, this would tend to carry them 

 faster than the wind during the retard, so that there would be 

 a gain in the total movement recorded by the cups over the 

 motion of the whirler and the free wind. This view loses 

 sight of the very important consideration that during a rising 

 wind the cups would lag behind, and presumably just the 

 amount of the acceleraton during a falling wind. This point 

 could only be settled by experiment, and the following facts 

 seem to show that this supposed effect is either inappreciable 

 or just the contrary to what is desired. 



1. The weight of a very light set of cups was increased four- 

 fold, and in the open air there was no change in the result. 



2. Two sets of cups, which were exactly alike except that 

 one was eight times as heavy as the other, were compared side- 

 by side. It was found that in light winds the lighter cups 

 gave two to four per cent more wind, and that they were 

 alike in higher winds. 



3. Professor Marvin increased the moment of inertia two to 



