December 3, 1891] 



NA TURE 



III 



England, which has resulted in an application to the Admiralty 

 to carry this recommendation into practical effect in connection 

 with the astronomical Observatory of the Cape of Good Hope 

 (belonging to the Admiralty). This application is at present 

 under the consideration of the Admiralty. 



"A fundamental investigation in astronomy, of great im- 

 portance in respect to the primary observational work of astro- 

 nomical Observatories, and of exceeding interest in connection 

 with tidal, meteorological, and geological observations and 

 speculations, has been definitively entered upon during the past 

 year, and has already given substantial results of a most pro- 

 mising character. The International Geodetic Union, at its 

 last meeting in the autumn of 1890, on the motion of Prof. 

 Foerster, of Berlin, resolved to send an astronomical expedition 

 to Honolulu, which is within 9° of the opposite meridian to 

 Berlin (171° west from Berlin), for the purpose of making a 

 twelve months' series of observations on latitude corresponding 

 to twelve months' analogous observations to be made in the 

 Royal Observatory, Berlin. Accordingly, Dr. Marcuse went 

 from Berlin, and, along with Mr. Preston, sent by the Coast 

 and Geodetic Survey Department of the United States, began 

 making latitude observations in Honolulu about the beginning 

 of June. In a letter from Prof. Foerster, received a few weeks 

 ago, he tells me that he has already received from Honolulu a 

 first instalment of several hundred determinations of latitude, 

 made during a first three months of the proposed year of obser- 

 vations ; and that, in comparing these results with the cor- 

 responding results of the Berlin Observatory, he finds beyond 

 doubt that in these three months the latitude increased in Berlin 

 by one-third of a second, and decreased in Honolulu by almost 

 exactly the same amount. Thus, we have decisive demonstra- 

 tion that motion, relatively to the earth, of the earth's instan- 

 taneous axis of rotation is the cause of variations of latitude 

 which had been observed in Berlin, Greenwich, and other great 

 Observatories, and which could not be wholly attributed to errors 

 of observation. This, Prof. Foerster remarks, gives observa- 

 tional proof of a dynamical conclusion contained in my Pre- 

 sidential Address to Section A of the British Association at 

 Glasgow, in 1876, to the effect that irregular movements of 

 the earth's axis to the extent of half a second may be produced 

 by the temporary changes of sea level due to meteorological 

 causes. 



" It is proposed that four permanent stations for regular and 

 continued observations of latitude, at places of approximately 

 equal latitude, and on meridians approximately 90° apart, 

 should be established under the auspices of the International 

 Geodetic Union. The reason for this is that a change in 

 the instantaneous axis of rotation in the direction perpendi- 

 cular to the meridian of any one place would not alter its latitude, 

 but would alter the latitude of a place 90° from it in longitude 

 by an amount equal to the angular change of the position 

 of the axis. Thus two stations in meridians differing by 90° 

 would theoretically suffice, by observations of latitude, to deter- 

 mine the changes in the position of the instantaneous axis ; but 

 differential results, such as those already obtained between 

 Berlin and Honolulu, differing by approximately 180° in longi- 

 tude, are necessary for eliminating errors of observation 

 sufficiently to give satisfactory and useful results. It is to be 

 hoped that England, and all other great nations in which science 

 is cultivated, will co-operate with the International Geodetic 

 Union in this important work." 



The celebration of the hundredth anniversary of the birth 

 of Faraday, recorded in our columns at the time, was next re- 

 ferred to. 



" A niatter of great importance in respect to the health of the 

 community was submitted to the Royal Society by the London 

 County Council, in a letter of date May x, 1891, asking for 

 information and suggesting investigation regarding the vitality 

 of microscopic pathogenic organisms in large bodies of water, 

 such as rivers which are sources of water-supply and which are 

 exposed to contamination. After some correspondence, it was 

 agreed, between the County Council and the Council of the 

 Royal Society, to enter upon an investigation, the expense 

 of which was to be defrayed partly by the London County 

 Council and partly by the Royal Society out of the 

 Government Grant for Scientific Research. When we 

 consider how much of disease and death is due to con- 

 taminated water, we must feel that it is scarcely possible 

 to over-estimate the vital importance of the proposed investi- 

 gation. Let us hope that the alliance between the London 



NO. II 53, VOL. 45] 



County Council and the Royal Society, for this great work, may 

 be successful in bringing out practically useful results. 



Prof. Stanislao Cannizzaro {^Copley Medal). 

 " Stanislao Cannizzaro, Senator of Italy, and Professor of 

 Chemistry in the University of Rome, has rendered invaluable ser- 

 vice to the philosophy of modern chemical science. The work of 

 Avogadro, in 181 1, and afterwards that of Ampere, had already 

 thrown much light on the relative weights of the molecules of 

 elementary bodies, and on the proportion in which those weights 

 enter into chemical combination. But it is to Cannizzaro that 

 we owe the completion of what they had left unfinished 

 He pointed out the all-important difference, hitherto overlooked, 

 between molecular and atomic weights, and showed (i) how 

 the atomic weights of the elements contained in a volatile com- 

 pound can be deduced from the molecular weights of such 

 compounds ; (2) how the atomic weights of the elements the 

 vapour-densities of whose compounds were unknown can be 

 ascertained by help of their specific heals. By these investiga- 

 tions the series of atomic weights of the elements, the most 

 important of all chemical constants, and the relation which these 

 weights bear to the molecular weights of the elements, have 

 been placed on the firm basis on which they have ever since 

 rested. It is to Cannizzaro that science is indebted for this 

 fundamental discovery, and it is this which it is proposed to 

 recognize by the award of the Copley Medal. 



Prof. Charles Lapworth, F.R.S. {Royal Medal). 

 "Prof. Lapworth is the author ofsome of the most original and 

 suggestive papers which have appeared in the geological literature 

 of this country for the last twenty years. Special reference may 

 be made to his researches on graptolites, and to his patient in- 

 vestigation by these means of the exceedingly complicated struc- 

 ture of the Silurian uplands of the south of Scotland. He has 

 been able not only to supply the key which has given the solution 

 of the stratigraphical ditificulties of that region, but also to 

 furnish theoretical geology with an array of new facts from which 

 to philosophize as to the mechanism of mountain-making. Of 

 not less importance are his detailed studies of the structure of 

 the North-west Highlands, and his demonstration of the true 

 order of stratigraphical sequence in that region of complex dis- 

 turbance As a stratigraphist he has attained the highest rank, 

 and he has likewise made himself a chief palseontological 

 authority on the structure and distribution of the Graptolitidse. 

 For some years past he has been engaged in a laborious study of 

 the Silurian and Cambrian rocks of the middle of England, the 

 detailed publication of which is awaited with much interest by 

 geologists. 



Prof Rucker, F.R.S. [Royal Medal). 



" In conjunction with Prof. Reinold, Prof. Riicker carried out 

 an important series of researches (extending over ten years) on 

 the electric resistance and other physical properties of liquid 

 films, in the course of which the fact was established that the 

 black part of a soap film in equilibrium has a uniform or nearly 

 uniform thickness of II or 12 micromillimetres, and that there is 

 an abrupt augmentation across its border to a thickness of about 

 30 or 40 micromillimeires in passing to the coloured portions, 

 rhis, considered in connection with the well-known sudden 

 opening out of the little black areas in an ordinary soap-bubble, 

 proves a minimum of surface-tension for some thickness between 

 10 and 50 micromillimetres, which in the ordinary soap-bubble, 

 unmodified by Reinold and Riicker's electric current, is tem- 

 porarily balanced in virtue of the abrupt change of thickness, a 

 proposition of fundamental importance in the molecular theory, 

 implying the existence of molecular heterogeneousness. 



" In theoretical calculations connected with the cojipounding 

 of dynamos and motors to produce constant potential difference, 

 constant current, or constant speed, electricians did not see their 

 way to obtain results of a sufficiently simple character to be of 

 use in practice, if they employed a function of the current which 

 fairly represented the magnetism. They were, therefore, com- 

 pelled to assume in such calculations that the magnetism was a 

 linear function of the current, although it was well known that 

 this was very far from being true when the current was large. 

 Prof. Riicker, however, developed a simple method of attacking 

 such problems, and showed how the magnetic saturation of the 

 iron might be taken into account, and a comprehensive solution 

 of the general problem of compounding dynamos and motors 

 obtained in a workable form. Prof. Riicker's paper containing 



