174 



NA TURE 



[DtCEMBEK 26, 1901 



language or refined rhapsodies on rural life and scenes, 

 but in natural vigorous words Bettesworth — that was the 

 name of the labourer- -gives his opinion upon sundry 

 persons, places and things he lias known. The ethno- 

 grapher will here and there find descriptions of country 

 customs and remedies which will interest him. 



LETTERS TO THE EDITOR. 

 [TAe Ediloy docs not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to (o) respond with the writers of rejeciei 

 manuscripts intended for this or any other part of NaTUKE. 

 No notice is taken of anonvmous commtinicalions.'i 



Relative Velocity in Streams. 



In your review of the report of M. Vallot from his observa- 

 tory on Mont Ulanc (p. 31) you speak of his finding that a 

 stream ceases to increase in speed in a channel of greater in- 

 cline than 3 in 100 as something unexpected. 



¥ot more than twenty years I have contended, in repeated 

 publications, that friction against the bed increasing pro- 

 gressively from the middle to the margin divides every stream 

 longitudinally into two halves, which roll spirally toward each 

 other. This spiral being determined by the friction, its helix 

 rises with the speed, or the increased friction depending on the 

 speed, which in turn depends on the slope of the channel. It 

 follows that beyond a certain speed the stream loses all the mo- 

 mentum gained by its fall in beating with the two outward- 

 moving undercurrents against the channel walls. In this way 

 the stream attains its kinetic equilibrium. If glaciers are plastic 

 or viscous bodies, they, too, must obey the same laws. 



Louisville, Kentucky, U.S.A. D. T. Smith. 



Change of Pitch of Certain Sounds with Distance. 



In Nature of December 12 (p. 129), Mr. F. M. West de- 

 scribes an observation made while walking up and down the 

 platform of a railway station. The pitch of the sound caused by 

 the steam escaping from an engine rose as he retreated from it 

 and fell as he drew near to it. 



As I gave the explanation of the same phenomenon in 

 Les Archives Nt'erlandaises (Arch. Neerl. Livre jubilaire, 

 November 1901), I may be permitted to give a summary in 

 these pages. 



The pitch will not only rise by retreating from the engine, 

 but also by bringing the ear nearer to the ground. The pitch is 

 due to reflection of the sound from the platform itself, for when 

 a large board is laid down on the ground between the engine 

 and the observer, the pitch will be heard to rise when the board 

 is raised. 



It is clear, therefore, that the pitch can be caused by inter- 

 ference of the direct and the reflected sound-waves, a phenomenon 

 wholly similar to Lloyd's experiment with light-waves. As in 

 Lloyd's experiment the elementary colours of the white light are 

 separated in space, so here the different pitches of sound will 

 predominate in different points of space, and a sort of sound- 

 spectrum will be formed. 



A mathematical examination enables us to analyse the 

 irregular vibration of a noise during a .short time, according to 

 Fourier, into a series of harmonic vibrations. Moreover, it can 

 be proved by calculation that the interference of the direct and 

 the reflected sound-waves must cause at any spot a series of 

 (impure) pitches to be heard. The wave-lengths of these 

 pitches must be i/i, 1/2, 1/3 .. . of the difference of distance 

 travelled over by both sounds. 



An experimental examination, made at the platform of a 

 railway statiim, has shown me that the pitch of the noise of an 

 engine fully agrees with the theory, .so far as the impurity of the 

 pitch permitted an exact exjieriment to be made. 



When the noise of a waterfall or rustling trees is perpen- 

 dicularly reflected by a wall, Baumgarten has observed the 

 change of pitch in the vicinity of this wall (Muller-l'ouillet, 

 " Lehrbuch der I'hysik," i. p. 732}. The above-mentioned re- 

 ,sult is also applicable in ihis case. In the neighbourhood of a 

 waterfall I obtained experimental results perfectly agreeing with 

 theory. D. van Oui.iK. 



Apeldoorn, December 15. 



NO. 1678, VOL. 65] 



CHEMICAL INSTRUCTION AND CHEMICAL 

 INDUSTRIES IN GERMANY., 



JUST now, when men of science and educationists are ; 

 continually directing attention to the superiority of 

 (ierman educational and industrial methods, especially 

 in the domain of chemistry, a report published among 

 the " Miscellaneous Series" of the Korei.un 0)ffice is most 

 apposite, and should be studied by all who are' truly 

 interested in the educational and comnjercial welfare of 

 the nation. 



The object of the report, which is compiled by Ur. 

 Frederick Rose, His Majesty's Consul at Stuttgart, is 

 " to show to what extent the German chemical indus- 

 tries have benefited by the sums expended by the 

 German .States on chemical instruction.' A perusal of 

 the contents of this highly interesting and instructive 

 report shows us that the German technical high schools 

 or polytechnics differ in tola from those of the United 

 Kingdoin. They are, in fact, more like our University 

 colleges, e.g. Owens College and Mason College (new 

 University of Birmingham). The older Universities in 

 Germany began to study chemical technology about the 

 middle of the seventeenth century. They thus laid the 

 foundation-stone of the present-day industrial chemistry 

 for which the country has become famous. As trade 

 and chemical industries gradually advanced, the Uni- 

 versities were found inadequate to train the greatly 

 increased number of chemists who were required. 'I'he 

 polytechnics (now called technical high schools) were 

 consequently founded. These are, without exception, 

 products of the nineteenth century. One must not, 

 however, lose sight of the fact that it is only within the 

 last two generations that the technical high schools have 

 assumed such prominence. They had first to learn what 

 was required of them if they were to exert a really 

 beneficial effect upon the welfare of the country. On 

 p. 8 of the report the following words appear, which we 

 trust some of our technical educationists will take to 

 heart : — 



" The study of architecture, engineering and chemistry 

 at the technical high schools left, at the beginning, much 

 to be desired, as the erroneous opinion prevailed that 

 it was not necessary for the students to devote them- 

 selves to the study of scientific works, but rather to ac- 

 quire a certain practical aptitude in superficial manipu- 

 lation. . . . Later on, however, it was clearly perceived 

 that the scientific foundation laid during the scientific 

 courses at the technical high schools formed the soundest 

 basis for the practical experience to be gained during 

 professional life." 



In the British polytechnics the teaching staff have no 

 social status, and the scale of remuneration depends 

 entirely upon the governing body, who have usually great 

 difficulty in making both ends meet. But in the Prussian 

 technical high schools, which are under the direct control 

 of the State, the members of the professional staff possess 

 the rank of full State officials, and the salaries are regu- 

 lated according to certain fixed limits. Indeed, so deeply 

 is the German Emperor convinced of the importance of 

 technical education that he has caused the directors of 

 the Prussian technical high schools to be admitted to 

 the Prussian Upper House, while a short time ago at the 

 centenary of the Berlin Technical High School he con- 

 ferred upon the Prussian technical high schools the right 

 to confer a new degree of Doctor of Engineering, thus 

 practically raising the technical schools to the level of 

 the Universities. 



Before the students are allowed to pass into the 

 technical high schools they must show that they have 

 obtained a preliminary education of a very high order. 

 Whilst it is no unusual thing in our polytechnics to find 

 students who have absolutely no knowledge of the 

 merest elements of arithmetic and who are (|uite unable 



