July 12, 1900] 



NATURE 



259 



the free period of oscillation, supposing its boundaries all rigid, 

 would not differ much from twelve lunar hours, and the forces 

 are connected with the dominant ocean tides by applying to such 

 an area, or to a system of such areas, the rule that "if to the 

 particles of water in a given oscillating system, each area of 

 uniform depth, and wherein the resistances are proportional to 

 the velocities of the particles, a series of simple harmonic forces 

 having for period the free period of the body of water be 

 applied and a permanent state established, then must the time 

 of elongation be simultaneous with the time when the virtual 

 work of the external periodic forces upon the system becomes 

 zero." Applying this rule, by means of the tidal-force diagrams 

 the time can be found when " the aggregate of the elementary 

 masses, each multiplied by the intensity of the tidal force in the 

 direction of the displacement of the element, and again by a 

 quantity proportional to the value of the maximum displacement 

 (since the oscillation is harmonic), is zero " : this is the time of 

 high or low water. The results of this method appear at once 

 in a few simple cases : thus in an east-and-west canal half a 

 wave-length long it is high water at the east end at the 

 component hour o or 12, the time meridian being understood to 

 be the meridian of the middle point of the canal ; in a 

 meridional canal one wave-length long, whose centre lies 



UNI VERS 11 Y AND EDUCATIONAL 

 INTELLIGENCE. 



Oxford.— Applications are invited for the new Wykeham 

 professorship of physics, referred to in a note on May 24 (p. 91). 

 The election will take place in November, and applications must 

 reach the Registrar not later than October 24. The following par- 

 ticulars are given in the University Gazette : — The subjects on 

 which the professor will chiefly lecture and give instruction will 

 be electricity and magnetism. The professor will have the 

 charge of any laboratory which the University may assign to him. 

 It is expected that rooms, now otherwise occupied, will be 

 assigned to the professor for a laboratory in the course of the 

 year 1901 ; 700/. will be appropriated to fitting up the labora- 

 tory, and provision has been made for spending 250/. a year for 

 the first two years on assistance and maintenance. As soon as 

 the professor is elected, he will be entitled to be admitted to a 

 Fellowship at New College of the annual value of 200/. In 

 addition, from January i, 1901, he will receive from New 

 College (l) an annual payment of 200/. ; and (2) a further annual 

 payment of 100/. so long as the College has funds available for 

 the purpose. It is anticipated that this further payment will be 

 paid for not less than twelve or thirteen years. 



between 45° south and 45° north latitude, it is high water at 

 both ends at the component hour 9 ; if the centre lies beyond 

 these limits, the component hour of high water at the ends is 3. 



Before laying down the oscillating areas, Mr. Harris gives a 

 number of lemmas which have to be borne in mind as modifying 

 the motions discussed. To quote one example: "Suppose a 

 stationary oscillation to exist in a canal communicating with a 

 tided sea ; let the length of the canal lie between o and \ \, 

 then at the time of high water outside it is high water through- 

 out the canal (e.g. many Alaskan canals). If the length lie be- 

 tween i \ and i A, it is low water for a distance of ^ A from the 

 head at the time it is high water outside (e.g. Irish Sea, node at 

 Courtown ; English Channel, node at Christchurch). If the 

 length be equal, or nearly equal, to ^ \, then the horizontal 

 motion at the mouth, instead of the vertical motion, determines 

 the time of tide within ; this tide will be three hours later than 

 the tide outside (e.g. the Gulf of Maine). 



The systems supposed to account for the principal semi-daily 

 movements of the oceans are outlined on the chart which we re- 

 produce in a reduced form ; the Roman numerals indicate the co- 

 tidal hours. The main systems are seven in number : (i) North 

 Atlantic, (2) South Atlantic, (3) North Pacific, (4) South Pacific, 

 (5) North Indian, (6) South Indian, (7) South Australian (solar). 



NO. 1602, VOL. 62] 



Prof. McCall Anderson, Professor of Clinical Medicine 

 in the University of Glasgow, has been appointed to the chair 

 of Systematic Medicine in the same University, in place of Sir 

 W. Gairdner, resigned. 



The war in South Africa has raised many questions of great 

 national importance which are fortunately receiving the atten- 

 tion of many thoughtful people. Prominent among these sub- 

 jects of discussion is the urgent problem of how to obtain an 

 improved supply of suitably educated officers, which was 

 recently dealt with in a paper read by the Headmaster of Eton 

 at the Royal United Service Institution. Dr. Warre maintains 

 that a wider diffusion of the knowledge of the elementa of 

 military science among the educated youth of the nation would 

 tend, not only to raise the standard of military knowledge in 

 the Army and Auxiliary Forces, but to improve the methods of 

 communicating that knowledge to the rising generation, an 

 indirectly widen the area from which a supply of well-educated 

 officers may constantly be drawn. The great majority of the 

 headmasters of our public schools agree with Dr. Warre, and 

 he has drawn up, at the request of the War Office, a memo- 

 randum in which he advocates the need for a new Act of 

 Parliament, the tenor of which should be " that all persons in 



