842 



NATURE 



[August 26, 1920 



tions. The total value of school buildings, sites, and 

 equipment is stated to be of the vast total of nearly 

 2,000,000,000 dollars. The school dollar income is spent 

 as follows : 3-3 cents on general control, 582 on 

 instruction, 155 on new buildings and grounds, and 

 23 miscellaneous. The average length of the school 

 year is stated to be 160 days, though the cities usually 

 provide a school term of nine months. More than 

 6,000,000 children attend school, on an average, less 

 than live months in each year. Great diversity exists 

 throughout the States, due to climatic conditions, the 

 scattered nature of much of the population, racial 

 differences, and varj-ing educational legislation, which 

 largely accounts for the striking differences which 

 prevail. The bulletin is well worthy the close atten- 

 tion of educational authorities in this country. 



Societies and Academies. 



London. 

 Physical Society, June 25.— Sir W. H. Bragg, presi- 

 dent, in the chair. — Dr. J. H. Vincent : The origin 

 of the elements. The atomic weights are regarded 

 as the weighted mean values of the atomic weights 

 of the isotopes of the elements ; but it is assumed 

 that, as a rule, the atomiic weight is near that of 

 some one isotope. Figures and tables are drawn up 

 showing how this accounts for the values of a large 

 number of atomic weights, if one also assumes that 

 the weights and positions in the periodic table of any 

 isotope are conditioned by laws similar to those hold- 

 ing in the recognised radio-active families. The 

 elements are all supposed to be derived from parent 

 elements by processes known to occur in actively 

 radiating families, but their radio-activity is not, in 

 general, detectable by the usual means owing to the 

 velocity of expulsion of the particles being low. The 

 possibility of the reversibility of some radio-active pro- 

 cesses is regarded favourably. The various difficulties 

 in connection with the views advocated are dis- 

 cussed, and some suggestions for experiments made. 

 Finally, the theory is used to explain the so-called 

 laws of the atomic weights of elements of low atomic 

 weight, and the shape of the curve obtained when 

 the atomic weights are plotted against Moseley's 

 numbers.— W. H. Wilson and Miss T. D. Epps : The 

 construction of thermo-couples by electro-deposition. 

 The method, which was devised to overcome the diffi- 

 culty of making satisfactory soldered joints between 

 the elements of thermopiles having a large number 

 of closely packed junctions, consists in using a con- 

 tinuous wire of one of the elements and coating those 

 parts of it which have to form the other element with 

 an electrolytic deposit of another metal. If the con- 

 ductivity of the latter is considerably greater than that 

 of the former, and a fairly thick sheath is deposited, 

 a thermo-couple is produced which is not appreciably 

 impaired in efficiency by the short-circuiting effect of 

 the core. Constantan wires coated with either copper 

 or silver sheaths were found to be suitable for most 

 purposes.— J. Guild : The use of vacuum arcs for inter- 

 ferometry. The paper discusses the relative merits 

 of short and long mercury arcs for this work, and 

 points out that the defect of the former is due to the 

 broadening of the spectrum lines consequent on the 

 high vapour pressure within the Tamp. It is shown 

 that by attaching a condensing bulb to the lamp, so 

 as to prevent excessive rise of vapour pressure, the 

 short lamp can be made practically as good as the 

 long one as regards sharpness of lines, while still 

 being of much greater intrinsic brightness.— S. Butter- 

 wortli : The maintenance of a vibrating system by 

 means of a triode valve. This paper gives a mathe- 

 matical analysis of the arrangement, previously 

 NO. 2652, VOL. 105] 



described by Eccles, whereby the vibrations of a 

 tuning-fork are maintained by means of a triode. 



Philadelphia. 



American Pliilosopliical Society, April 24. — Dr. G. E. 



Hale, vice-president, in the chair. — Prof. E. W. 

 Brown : The problem of the evolution of the solar 

 system. — W. H. Wriglit : Certain aspects of recent 

 spectroscopic observations of the gaseous nebulas 

 which appear to establish the relationship between 

 them and the stars. The paper summarises in non- 

 technical terms the evidence afforded by a study of 

 the stellar condensations in the planetary or small 

 gaseous nebulae which are shown to be spectro- 

 scopically identical with stars of the Wolf-Rayet group 

 (Pickering's Class O). A brief account is given of 

 some of the present-day conceptions of stellar evolu- 

 tion for the purpose of indicating the somewhat 

 critical nature with respect to these ideas of the 

 relationship indicated. — ProL E. P. Adams : The Ein- 

 stein theory. The extension of ihe principle of rela- 

 tivity and the resulting revision of the concepts of 

 space and time led to Einstein's interpretation of 

 gravitation as a property of space itself when 

 modified by the presence of matter.- — Dr. L. A. Bauer : 

 The results of geophysical observations during the 

 solar eclipse of May 29, 19 19, and their bearing upon 

 the Einstein deflection of light. The present paper 

 gives the results of a special study of the cause of the 

 non-radial effects of the light deflections observed by 

 the British expedition at Sobral, Brazil. It is shown 

 that these non-radial . effects may be completely 

 accounted for by incomplete elimination of differential 

 refraction effects in the earth's atmosphere. The 

 same cause may apparently also explain why the 

 observed radial deflections of light exceeded, on the 

 average, by about 14 per cent, the amounts predicted 

 on the basis of the Einstein law of gravitation. — 

 Prof. J. B. Whiteliead : The high-voltage corona in 

 air. The paper describes the nature of the corona 

 and recent studies of the laws governing its appear- 

 ance in high-voltage circuits. Its influence as a limit- 

 ing factor in long-distance transmission occurs through 

 deterioration of insulation and a leakage loss of power 

 between the high-voltage lines. The appearance of 

 corona on a clean round wire is very sharply marked, 

 and may be used for the measurement of high alter- 

 nating voltages to a degree of accuracy not heretofore 

 possible. — Prof. D. C. Miller : The velocity of ex- 

 plosive sounds. Most of the experiments were made 

 in connection with lo-in. and 12-in. rifles, though a 

 few were made with 6-in. and 8-in. guns. The 

 amount of powder charge and the value of the in- 

 ternal pressure developed in the gun are taken into 

 account. The sounds were received by means of 

 specially constructed carbon-granule microphones, 

 those for use near the gun being of unusually rugged 

 construction, while others were of a very sensitive 

 type. The records were made by a specially con- 

 structed moving-film camera in connection with a 

 string-galvanometer capable of recording from six 

 stations simultaneously, of the type used by the U.S. 

 Armv for sound-ranging. Meteorological observations 

 were made by special observers in the distant stations 

 and on the "field near the guns at the time of the 

 experiments, and continuous records were made at 

 the Proving Ground Headquarters and at the United 

 States Weather Bureau Station. These observations 

 covered temperature, barometric height, humidity, 

 wind velocity, and wind direction. Measurements 

 were also made of the velocitv of the sound at a 

 series of stations located on a line at right angles to 

 the line of fire and on a line at 4^° to one side of the 

 line of fire. Heretofore there has been a general 



