April 28, 1898] 



NATURE 



613 



published. He was best known to English pharmacists through 

 his '* Plant Analysis," a translation of which, by his former 

 pupil, Henry G. Greenish, was published in 1883. His work 

 on alkaloids was, however, that by which he is most entitled to 

 fame. The mydriatic alkaloids were his special field, and his 

 syntheses of conine and atropine are amongst the most brilliant 

 achievements of modern chemistry. In 1885 the Pharmaceutical 

 Society of Great Brit lin conferred the third Hanbury medal 

 upon him. 



The Kew Observatory Committee have issued their Report 

 for the year 1897. During that period the magnetic curves have 

 been free from any very large fluctuations ; the mean westerly 

 Declination for the year was 17° 6', and the mean Inclination, 

 67° 20'. The meteorological observations conducted for the 

 Meteorological Council call for no special remarks ; the electro- 

 graph has been in nearly constant operation since January 19. 

 Several hours' record were lost owing to the trace being off the 

 sheet ; Dr. Chree states that it is difficult to see how such loss 

 can be avoided without either duplicating part of the apparatus, 

 or by risking possible loss of negative trace by shifting the 

 position of the zero line on the sheet. Sketches of sun-spots 

 were made on 165 days ; it has been decided to discontinue the 

 eye observations, owing to the elaborate photographic work now 

 done elsewhere. Among the various experiments and researches 

 in connection with the several departments we observe that 

 attention has been given to the comparison of platinum and 

 mercury thermometers at high temperatures, in view of repeated 

 requests for direct high temperature verifications. Experiments 

 are also being made as to the thermometric properties of different 

 kinds of glass, the results of which will be eventually published. 

 The usefulness of the institution is shown by the continual in- 

 crease in the number of instruments submitted for verification ; 

 the increase during the year in question amounted to nearly three 

 thousand. In addition a large number of watches and marine 

 chronometers were received for trial. 



A NUMBER of investigations have been made on the connec- 

 tion of various terrestrial phenomena with the period of rotation 

 of the sun, but the results obtained have not been definite 

 enough to establish the reality of a twenty-six-day pferiod of 

 meteorological phenomena. In connection with this question. 

 Prof. Arthur Schuster subjects the methods of finding hidden 

 periodicities — small periodic variations hidden behind irregular 

 fluctuations — to vigorous analysis in Terrestrial Magnetism 

 (March), with the object of introducing a little more scientific 

 precision into the treatment of problems involving hidden 

 periodicities, and of applying the theory of probability in such 

 a way as to assign a definite number for the probability that the 

 effects found by means of the usual methods are real, and not 

 due to accidental circumstances. The methods described show 

 the lines which investigations on the periodicity of phenomena 

 should follow, and point to several interesting subjects to which 

 they may profitably be applied. As to results already published. 

 Prof. Schuster concludes : — " The general result of a critical 

 examination of the published investigations on the twenty-six- 

 day period leads me to think that, although the magnetic ele- 

 ments and the occurrence of thunderstorms seem to be affected 

 by a period of twenty-six days and of its first multiple, the 

 subject requires a good deal of further study before we can 

 be sure as to the exact nature of the period. Even though it 

 may be considered as proved, it must not be necessarily assumed 

 that it is due to solar action. If it was a question merely of 

 magnetic disturbances, there does not seem to be any great im- 

 probability, however, that some periodicity may be connected 

 with the sun's rotation about its axis, especially at times of great 

 sun-spot activity." 



NO. 1487, VOL. 57] 



In a short note in the Comptes rendus (No. 15, April 1898), 

 M. Thi^baut gives us the result of his investigations on the 

 frequency of the extra large tides which occur at the March 

 equinox. He has used the number previously published in the 

 Connaissance de Temps since the beginning of the century, and 

 has shown that the relative magnitude of the coefficients of the' 

 tides at the syzygies vary notably from one year to another, but 

 that the rule given below is subject to some exceptions. From 

 the theoretical point of view this law of the variation of the 

 coefficients assigns to the return of this great tide a period of about 

 nine years if only one equinox is considered, or four and a half 

 years if one indifferently takes account of the spring or autumn 

 equinoxes. The principal cause of these variations he attributes 

 to the movement of the moon's perigee, which completes one 

 revolution in about 8 years and 310 days. Taking into account 

 all the circumstances of the phenomenon he discovered a re- 

 markable period of 412 days, at the completion of which the sun 

 returns to the lunar perigee. This period he calls the "annee 

 perigeenne " ; and it does not differ very much from two other 

 interesting periods, one of 41 3 "4 days, which corresponds to 

 14 lunar months (synodic), the other of 413 "3 days, or 15 

 anomalistic months. 



The theory which attributes volcanic eruptions to disturbances 

 produced beneath the earth's crust by luni-solar tide-generating 

 forces would receive striking confirmation by the establishment 

 of a connection between the periods of greatest volcanic 

 activity and the phases of the moon which give rise to spring 

 tides. Prof. Eugenio Semmola, writing in the Atti del R. 

 Istituto d' Iiicoraggiamento (Naples), has compared the periods of 

 maximum and minimum activity of Vesuvius with the phases of 

 the moon during the two years from July 1895 to July 1897. 

 The conclusions drawn fiom these observations are entirely of a 

 negative character ; the number of days of maximum and 

 minimum activity being largely in excess of the number of 

 lunations in the same period, and the fresh flows of lava being 

 distributed fairly evenly between the moon's four quarters. A 

 comparison of the more violent eruptions of Vesuvius from the 

 year 1800 to the present time shows that in five of these the 

 nearest phase of the moon was the new or full moon, and in 

 the remaining five the nearest phase was the first or last quarter. 

 It thus appears that no relation exists between the activity of 

 Vesuvius and the phases of the moon. 



The Journal de Physique for April contains the continuation 

 of an important paper, by M. A. Leduc, on the densities and 

 molecular volumes of gases. M. Leduc has established, under 

 the name of "law of molecular volumes," a limiting law, 

 which he proposes as a substitute for the principle of Avogadro 

 and Ampere. This law he applies to the calculation of the 

 densities and coefficients of expansion of a number of gases, 

 and every experimental determination appears to agree with 

 the predicted results. 



In the same journal, M. J. Mace de Lepinay gives a proof 

 that the fringes of caustics and the supernumerary arcs of rain- 

 bows can be regarded as true interference-fringes. — M. P. Morin 

 considers the influence of the length of magnets on their mean 

 intensity of magnetisation. In needles of the same material 

 and cross-section magnetised to the point of saturation, the 

 intensity of magnetisation and the magnetic density at the two 

 ends are independent of the length of the needle, and the same is 

 the case for all sections taken at equal distances from the 

 extremities. 



New magazines devoted to discussion of the Rontgen rays 

 appear to be springing up in every direction. From St. Louis we 

 have received the American X-Ray Journal, which is stated on 

 the cover to be "a monthly devoted to the practical application 



