J 66 



NATURE 



[June 14, 1900 



subject of the higher education, and was anxious to include in 

 his proposed University the best features to be found in institu- 

 tions in America and elsewhere. At the foundation of the 

 University in 1889, Mr. Clark gave it an endowment of one 

 million dollars, to which he added a like amount later on. By 

 his death, the institution receives his magnificent library of rare 

 and costly books. Clark University is perhaps unique among 

 the educational institutions of the United States. It is devoted 

 entirely to post-graduate studies, and recently celebrated its 

 tenth anniversary. 



As announced last week, a series of festivities began at Cracow, 

 on June 7, in commemoration of the 500th anniversary of the foun- 

 dation of Cracow University. A Reuter correspondent states that 

 a large number of men of science, including representatives of most 

 of the European universities and colleges, attended the celebration. 

 The Austrian and foreign investigators went in procession on 

 Thursday morning to the Church of St. Mary, where a Papal 

 Brief in reference to the celebration was read. The graves of 

 the founders of the University were visited and wreaths deposited 

 upon them. At the special commemorative meeting subsequently 

 held, speeches in Latin were delivered by Prof. Tarnowski, the 

 rector, and Dr. von Hartel. An illuminated address was pre- 

 sented by a deputation from Oxford University. The proceed- 

 ings terminated with the distribution of the diplomas of honour 

 to those upon whom the honorary degree of doctor has been 

 conferred. 



The new Directory of the Board of Education, South Ken- 

 sington, containing regulations for establishing and conducting 

 science and art schools and classes, has just been published. 

 Many of the regulations have been modified, more particularly 

 those referring to administrative matters and practical work. 

 The syllabus of practical mathematics has been revised, but the 

 subjects remain much the same as were prescribed in last year's 

 syllabus. A syllabus of an advanced stage of practical mathe- 

 matics has been added. The syllabus of mineralogy has been 

 slightly modified and recast. The laboratories in a School of 

 Science are to be available for preparation work by students of 

 the school beyond the school hours of the time-table. Courses 

 of work for Schools of Science in rural districts have been added. 

 The obligatory subjects of the elementary course for men are : — 

 (l) mathematics; (2) chemistry (with practical work); (3) 

 physiography (Section I.) or elementary physics (with practical 

 work) ; (4) biology (Section I.) or elementary botany (practical 

 work may be in the field or garden); (5) drawing, practical 

 geometry, or practical mathematics. Manual instruction in its 

 application to workshop and garden must also form part of the 

 course, which is intended to cover two years. The elementary 

 course for women in Schools of Science differs slightly from the 

 foregoing. Physics and chemistry are optional for the second 

 year, and hygiene may be taken instead of botany. Practical 

 mathematics is not included. Separate advanced courses of 

 work are prescribed for men and women who have passed 

 through the elementary courses. Managers of schools are now 

 allowed the option of having the grant for practical chemistry in 

 the advanced course assessed by the inspector or on the results 

 of examination in the advanced stage. The announcement 

 made last year that examinations in the elementary stages of 

 science and art subjects will only be held upon special applica- 

 tion, in which case a fee for each paper asked for will be 

 charged, is ratified. This probably means the abolition of 

 examination in the elementary stages; for apparently nothing 

 can be gained by arranging for the examination of candidates. 



SOCIETIES AND ACADEMIES. 



London. 

 Physical Society, June 8.— Dr. J. H. Gladstone, F.R.S., 

 Vice-President, in the chair. — A paper on the magnetic proper- 

 ties of alloys of iron and aluminium (Part ii.), by S. W. 

 Richardson and L. Lownds, was read by Dr. Richardson. 

 Experiments have been made to ascertain in whit way the 

 hysteresis loss between given limits of the field strength is con- 

 nected with the temperature for an alloy containing 3-64 per 

 cent, of aluminium. The experiments show that the hysteresis 

 loss attains a maximum value at a temperature considerably 

 higher than the temperature of maximum induction. The 

 changes produced in the magnetic properties of the alloy by 

 heating and subsequent cooling have also been investigated. 



NO. 1598, VOL. 62] 



The properties depend largely on the previous history of the 

 specimen, but there does hot appear to be any essential 

 difference between the behaviour of the alloy during heating 

 and cooling (except near the temperature of minimum perme- 

 ability). Experiments have also been conducted on the abrupt 

 change in the permeability that takes place at a temperature of 

 about 650° C. The conclusions arrived at are as follows : — (i) 

 The hysteresis loss at first diminishes as the temperature rises. 

 It then increases and reaches a maximum at about 550° C. On 

 further heating it falls off rapidly, and is negligible at 700° C. 

 (2) The magnetic properties of the specimen depend largely on 

 its previous history. (3) There is no essential difference 

 between the behaviour during heating and cooling except near 

 the temperature of minimum permeability. (4) An abrupt 

 increase in the permeability takes place at about 650° C. during 

 heating, followed by an equally abrupt diminution on further 

 heating. (5) This abrupt change is more marked with falling 

 than with rising temperatures. (6) Continued heating and 

 cooling diminish the permeability. (7) The curve connecting 

 temperature of minimum permeability and percentage of 

 aluminium is a straight line. (8) The microscopic examination 

 of the specimens shows the presence of crystals. Prof. S. P. 

 Thompson asked if the specimens had been kept for any length 

 of time at a high temperature, because crystals changed and 

 grew in metals at temperatures even far below their melting 

 points. Prof. Reinold asked if any specimens had been ex- 

 amined where the crystalline structure had not been observed. 

 Mr. Blakesley asked if any explanation of the orientation of the 

 crystals could be given. The chairmain said it was difficult to 

 know exactly what substances were being dealt with. They 

 might be pure alloys or mixtures of two or three alloys with 

 iron or aluminium. Dr. Richardson in reply said the crystals 

 might be dissolved in nitric acid and analysed, but at present he 

 did not know their composition. — Mr. W. Campbell then read a 

 note on crystallisation produced in solid metal by pressure. In 

 the preparation of sections of tin, particles cling to the file 

 and, if allowed to remain, tend to tear the surface of the metal. 

 The effect is not immediately noticeable, but on etching the 

 polished surface there appear, besides the usual structure of the 

 tin, lines of much smaller crystals with irregular boundaries but 

 possessing different orientation. The effect is only superficial 

 because it can be removed by polishing. The same behaviour 

 is noticed in some alloys, and it would thus appear that the 

 pressure of a file is sufficient to cause a metal or an alloy to re- 

 arrange itself. Prof. S. P. Thompson suggested that the 

 effect might be due to local heating caused by tearing rather 

 than to pressure. Mr. Campbell said that the effect was not 

 due to the heating of the file, because if the. file were kept per- 

 fectly clean no crystals formed. Prof. S. P. Thompson asked 

 if scratching the surface with a diamond produced crystallisa- 

 tion. The author said he had tried with a sharp knife without 

 success, but cutting with a blunt chisel produced crystallisation 

 along the chisel mark.— A paper on the viscosities of mixtures 

 of liquids and solutions was read by Dr. C. H. Lees. Three 

 formula have been suggested for expressing the viscosity 

 of a mixture in terms of the percentages and viscosities 

 of its constituent parts. The first of these represents 

 the viscosity as being the sum of a number of terms, each 

 one of which is the product of the percentage of any con- 

 stituent and its viscosity. The second formula represents the 

 logarithm of the viscosity in a similar manner, and the third one 

 the reciprocal. None of these formulse represent the viscosity 

 of a mixture with closeness. The author suggests a formula in 

 which the wth power of the reciprocal of the viscosity of a 

 mixture is equal to the sum of a number of terms, each one of 

 which is the product of the percentage of any constituent, and 

 the ;«th power of the reciprocal of the viscosity of that con- 

 stituent. This formula gives satisfactory agreement, and, more- 

 over, leads to Slotte's formula for the variation of viscosity with 

 temperature.— The secretary read a note from Prof. Wood on 

 an application of the method of striae to the illumination of 

 objects under the microscope. The object chosen was powdered 

 glass immersed in cedar oil of the same refractive index. The 

 glass particles were aliaost invisible under ordinary conditions of 

 illumination. The illuminating system was then arranged as 

 follows :— A screen, bounded by a straight edge, was placed m 

 front of an incandescent gas lamp, so as to cut off half of the 

 mantle, and give a source of light bounded by one perfectly 

 straight edge. A small lens of very short focus was placed 

 below the stage as close as possible to the object. The lamp 



