July 22, 1909] 



NATURE 



119 



important universities in the country. During his speech 

 Sir Alexander Kennedy made it clear that the old system 

 of apprenticeship has become inadequate. The function of 

 the laboratory, he said, is to try to let a man learn by 

 handling, experiment, and measurement the nature of the 

 materials with which he will have to deal later. The 

 extraordinarily rapid progress which has been made in 

 mechanical and electrical engineering during the last 

 generation has been largely due. Sir A. Kennedy thinks, 

 to the good training all over the country of the men who 

 have to carry out the details of the work. On the part 

 of colleges and universities, he continued, there is a 

 tendency to attempt to make students do a great deal too 

 much. While it is necessary that an engineer shall have 

 a knowledge of a great many things before he gets to 

 his profession, he cannot acquire much knowledge in three 

 years. It may be hoped that a strong university with 

 a strong man at its head will draw a very distinct line 

 in some common-sense fashion in defining what knowledge 

 shall be imparted to the students. Sir William Mather 

 proposed a vote of thanks to Sir A. Kennedy, and expressed 

 his disappointment at the neglect displayed by the large 

 engineering firms of the Manchester district in connection 

 with the higher development of engineering science among 

 young men. The success of engineering in the future will 

 depend almost wholly on elements quite different from those 

 which have distinguished it in the past. The next genera- 

 tion of engineers must be trained carefully by methods 

 enabling them, above all things, to combine economy with 

 efficiency. The technical school must perforce stop short 

 of what may be called the practical part of applying 

 machinery in the best possible way. To ensure success, 

 there must, ho continued, be a certain number of young 

 students devoting themselves to laboratory work, and this 

 extension of Manchester University must prove of great 

 usefulness. 



SOCIETIES AND ACADEMIES. 

 London. 



Physical Society, yune 25. — Dr. C. Chree, F.R.S., presi- 

 dent, in the chair. — A transition point in zinc amalgam : 

 Prof. H. S. Carhart. The paper gave the preliminary 

 results of an investigation which has for its primary object 

 the determination of the heat of dilution of zinc amalgams. 

 This heat of dilution is negative, that is, the dilution of 

 zinc amalgam by the addition of mercury absorbs heat. In 

 the course of the experimental work, which was conducted 

 by Dr. W. D. Henderson, phenomena so extraordinary 

 were encountered that the concentration at which they 

 occur was called a transition point in zinc amalgam. The 

 method employed was electrical, by means of a concentra- 

 tion cell, the only difference between the two legs of the 

 cell of H-form being in the concentration of the amalgam 

 composing the electrodes. — A method of producing an in- 

 tense cadmium spectrum, with a proposal for the use of 

 mercury and cadmium as standards in refractometry : Dr. 

 T. M. Lovwry. Of the twenty-six wave-lengths that have 

 been used in the study of rotatory dispersion (Proc. Roy. 

 Soc, Ixxxi., p. 472, November ig, 1908) the following 

 seven have been found to be the most suitable for genera! 

 use : — 



Li Cd Na Hg Cd Cd Hg 



6708 6438 i;8Q3 5461 50S6 4800 4358 

 In refractometry it has been customary to use the series ; — 

 Ha Na H^ Hy 



6560 5893 4S61 4341 

 This series has the disadvantages (i) that the chief standard 

 Na 5893 is a doublet, and (2) that the other three lines 

 are of such weak intensity that they are useless for the 

 m.njority of optical measurements. It is therefore urged 

 that — in view of the readiness with which the mercury and 

 cadmium spectra can now be produced — the mercury green 

 lino should be generally adopted in place of sodium as chief 

 standard in optical work of all kinds, and that the hydrogen 

 lines should be abandoned even as secondary standards in 

 favour of the series of wave-lengths set out above. — 

 The measurement of wave-length for high-frequency elec- 

 trical oscillations : A. Campbell. The experiments had 

 for their object the calibration of wave-meters for the 

 measurement of the high frequencies (200,000 up to 

 NO. 2073, VOL. 81] 



1,000,000 ~ per second) used in wave-telegraphy. Two 

 wave-meters (A and B) were tested, both being of the type 

 consisting of a series of self-inductance coils used singly 

 (L) in series with a variable air-condenser (K) and a thermo- 

 ammeter, the reading of K being obtained by altering the 

 capacity until the circuit shows resonance with the working 

 circuit. The coils of wave-meter (A) were wound with 

 solid wire, those of (B) with stranded wire (7/363), each 

 strand being separately insulated. The absolute value of 

 the frequency was determined by photographing spark- 

 trains in the primary circuit by means of a rotating mirror 

 running at a constant and accurately measured speed. The 

 value of the frequency deduced from the measured values 

 of K and L with wave-meter (B) were in close agreement 

 with the actual frequency deduced from the spark-photo- 

 graphs. With wave-meter (.'\) the agreement was natur- 

 ally not nearly so close, but was much improved when the 

 values of the self-inductances of the solid wire coils were 

 corrected to the high-frequency values by the formulas of 

 Heaviside and L. Cohen. — .^n electromagnetic method of 

 studying the theory of and solving algebraical equations of 

 any degree : Dr. Russell and Mr. Alty. The problem of 

 finding the roots of an algebraical equation of the nth 

 degree is identically the same as that of finding the posi- 

 tions of the " neutral points," that is, the points where the 

 resultant force due to the earth and definite currents in n 

 long vertical wires is zero. The n wires are arranged at 

 any convenient distances apart in a plane which '^ at right 

 angles to the magnetic meridian. The currents in the 

 wires are then adjusted to certain values which are readily 

 found by the methods of partial fractions. If x^ and y, be 

 the coordinates of one of these neutral poin ts m easured with 

 reference to certain definite axes, -'V, +y,v' — i is a pair of 

 roots of the original equation. All the real roots lie on the 

 axis of X which cuts the wire at right angles. The posi- 

 tions of the neutral points thus determine all the roots, 

 real and imaginary, of the given equation. The peculiar 

 advantage of the method is that it is easy to see, in many 

 cases almost at once, what effect varying the value of the 

 coefficient of any power of x will have on the roots of the 

 equation. — The sine condition in relation to the coma of 

 optical systems : S. D. Chalmers. The condition for the 

 correction of coma in a centred optical system is the well- 

 known sine condition. This has been proved by Clausius, 

 Helmholtz, Hockin, and others, and the importance of this 

 condition in the design of optical systems has been pointed 

 out by Abbe, Steinheil, Conrady, and others. The present 

 paper shows how to obtain the relation between the coma of 

 a system and the errors in the sine condition. — A new F^ry 

 thermo-electric calorimeter : Dr. C. V. Drysdale. This 

 form of calorimeter can be used continuously, and permits 

 the value of the pas produced in a gas-works or producer- 

 plant to be watched from time to time. — An instrument 

 for measuring the strength of an intense horizontal mag- 

 netic field : F. W. Jordan. The method consists in 

 measuring directly the transverse force on a conductor 

 traversed by a current in a direction at right angles to the 

 field. — A method of determining the sensibility of a 

 balance : Prof. PoyntinK- — The balance as a sensitive 

 barometer : Mr. Todd. 



Challenger Society. June 30. — Dr. A. E. Shipley in 

 the chair. — Colour changes in tropical sea perches from 

 the Bermudas : C. T. Reg:an. In one case an individual 

 specimen exhibited successively the coloration of three so- 

 called " species." — Recent observations of Prof. Otto 

 Pettersson on tide-like movements in deep water : Dr. 

 H. R. Mill. Daily observations on temperature and salinity 

 were made at close intervals from surface to bottom in 

 the Gullmar Fjord, when covered by ice, between 

 January 30 and March 25 of this year. The effect was 

 I hat of an invasion of sea water from the Skagerack twice 

 in a lunar period, followed by a withdrawal of the sea 

 water and the filling up of the upper part of the fjord 

 with brackish land water in rhythmical succession, and 

 Prof. Pettersson inclined to the belief that these move- 

 ments were of tidal origin. Dr. Mill pointed out that 

 Sir John Murray and he had shown that similar effects of 

 a non-periodical kind were produced in sea- and fresh- 

 water lochs of Scotland by the action of wind, and that 

 he had shown analogous effects on the Atlantic coast of 

 the Hebrides. 



