May 13, 1909J 



NA TURE 



3<9 



dorsal fin-spinoR. The most interesting discovery recorded 

 is that of a now palxoniscid fish, Rhadinichthys deani, 

 from the uppermost Devonian shales of Kentucky. It 

 occurs in phosphatic nodules, and the slate of preserva- 

 tion is such that even the brain and organ of hearing can 

 be examined and described. According both to Dr. East- 

 man and to Dr. G. H. Parker, the brain, semi-circular 

 canals with ampulla, and even some of the blood-vessels, 

 are actually phosphatised, and can be perfectly exposed by 

 cutting away the investing bone. Dr. Parker adds a 

 detailed description of these parts, showing that they differ 

 in no respects from those of a typical modern bony fish, 

 but the accompanying illustrations from photographs are 

 unfortunately not satisfactory. Dr. Easiman concludes his 

 memoir with a useful list of the Devonian fishes hitherto 

 discovered in North America. 



\\"e have received from the Meteorological Office charts 

 referring to the meteorology of the North Atlantic and 

 Indian Oceans, and from the Deutsche Seewarte similar 

 charts for the North .Atlantic, for the months of .April 

 and May, igoq, which are, as usual, replete with mean 

 statistical and current information useful to seamen. 

 In addition to data relating to normal conditions of winds, 

 currents, &c., both institutions give special charts of fog 

 and mist in the North .\tlantic. During the warm season, 

 from April to .August, fog is a source of great danger In 

 navigation, especially on the eastern part of the New- 

 foundland Bank, owing to marked differences of tempera- 

 ture between sea and air, and this danger is increased by 

 the southern drift of icebergs across the sailing routes. 

 From a useful report on the state of the ice in the Arctic 

 seas in 190S, recently issued by the Danish Meteorological 

 Institute, the opinion is expressed that there will be no 

 abnormal risk from ice in igog either along the soulli- 

 west of Greenland or near Newfoundland. 



To the Cairo Scientific Journal for January last Mr. 

 B. F. E. Keeling communicates an Interesting paper on 

 climate changes in Egypt. There is a strong belief 

 amongst residents that changes have occurred within the 

 last ten or tw-cnty years (possibly due to increased irriga- 

 tion) which are distinctly " sensible," without the aid of 

 instruments. Mr. Keeling quotes the mean temperature 

 at -Abbassia for each pentade from 1870-1904, and for the 

 four years 1905-S ; but the results show that the differences 

 are hardly greater than inight be caused by difference of 

 exposure of the thermometers. As regards humidity, also, 

 there is very little evidence of any decided change during 

 the last forty years. It is confidently asserted by many 

 persons that the rainfall has increased during quite recent 

 years, but the author shows that there is little, if any, 

 evidence of such being the case. The total rainfall of any 

 year is often influenced by the fall on a single day, and 

 is consequently very variable from one year to another ; 

 the driest year on record at Abbassia is 1892, with little 

 more than a quarter of an inch of rain, and the wettest, 

 1904, with less than 3 inches, the mean for 1887-1908 

 being approximately 14 inches. 



I.v No. I, vol. i. (second series), of the Proceedings of 

 the Tokyo Mathematico-physical Society, Mr. H. Nagaoka 

 publishes the results of a recent research on the complex 

 structure of some of the lines in the spectrum of mercury. 

 The experiments were made with a 35-plate echelon 

 spectroscope made by Hilger, and having a resolving 

 power of 430,000 for light of wave-length 5000 .Angstrom 

 units. The lines at \ 5790, A. 5769, and K 5461 were 

 analysed, and .Mr. Nagaoka finds several companions in 



NO. 2063, VOL. 80] 



each case which were not recorded by Janicki, Galitzin, 

 Stansfield, or Baeyer. .A remarkable feature of the com- 

 panions of the green, line (\ 54^0 's, the symmetricat 

 arrangement of, certain pairs of them about the principal 

 line, and an apparent constancy of wave-length difference 

 between consecutive lines. Further research will be 

 necessary to establish these features as objective realities, 

 a point which is not overlooked by the author, who dis- 

 cusses at length the possibility of certain lines being 

 illusory, optical phenomena. 



The origin of the colours of the spectrum forms the 

 subject of an article, by Prof. P. Zeeman, in the Fivista 

 di Scicnza, v., 9. The first part is mainly philosophical 

 in character, and deals with the question whether white 

 light is really a mixture of rays of different wave-lengths 

 or a mere succession of impulses, the phenomena of colour 

 in the latter case being due to the action of the spectro- 

 scope. The second part contains a summary of recent 

 results relating to magnetic action on light. Some recent 

 experiments on the shifting of the middle line of a 

 triplet are described by Prof. Zeeman in the Proceedings 

 of the Amsterdam Academy, published January 27. lr> 

 the Archives N^crlandaises (2), xiii., p. 260, Prof. Zcemar> 

 discusses the following questions :— applications of the de- 

 composition of rays to the measurement of the intensity 

 of magnetic fields ; relation between the intensities of the 

 components of a triplet ; the dissymmetry in intense fields ; 

 observations by Fabry and Perot's methods; determination 

 of the charge on electrons ; observations in the directior> 

 of lines of force ; and dissymmetry of the triplets in the 

 spectrum of tungsten. A note on Hale's observations of 

 the magnetic decomposition of the lines of the spectra in 

 sun-spots appeared in the Physihalische Zcitschrift, ix., 

 ^3. PP- »34. 835- 



.A SIMPLE method of finding indices of refraction of 

 liquids under the microscope is described by Dr. Enrico 

 Clcrici in the Atti dei Lincei. xviii., 7. In its simplest 

 form it consists of a glass slip with a thick cell, and a 

 triangular glass prism cemented on it.. A line ruled on 

 the under side of the prism is brought into collimation 

 with a wire in the focal plane of the eye-piece, and when 

 the cell is filled with any liquid the apparent displacement 

 of the line determines the index of refraction. 



On September 21, iqoS, Dr. Hermann Minkowski read 

 a paper before the German Naturalists' and Medical 

 .Association at Cologne on " Space and Time." It was his 

 intention to develop the ideas into a more complete theory 

 of mechanics, in which time would appear to be regarded 

 as a fourth dimension coordinated ' with the three 

 dimensions of space. Unfortunately, Minkowski did not 

 live to realise his project, his life coming to a, premature 

 end on January 12. In accordance with a wish expressed 

 by him, " Space and Tiine " has now been printed by the 

 Teubner Press, of Leipzig, with a preface by Prof. 

 Gutzmer, of Halle, and a portrait of Minkowski. It is 

 an interesting memorial of the autlior, and the printing 

 and general get-up are of the best. 



Designers of posts and brackets for electric street light- 

 ing will be interested in two well illustrated articles on 

 these fittings in the .April number of the Illuminating 

 Engineer of New York. Although many of the posts 

 figured are most elegant in design, there is obviously a 

 tendency in America to introduce Corinthian columns more 

 appropriate for supporting substantial buildings than arc 

 or incandescent lamps. 



