.78 



NATURE 



[August 4, 1925 



included, the author establishes the important strati- 

 graphical fact that there is no single, definite, per- 

 sistent and easily recognisable sandstone correspond- 

 ing to the formerly so-called Dakota Sandstone, but 

 that a group. of sediments to which the name Dakota 

 is given represents successive accumulations of sedi- 

 ments near the strand-line of an advancing Cretaceous 

 sea, presumably Upper Cretaceous, but not neces- 

 sarily so. Hence the group differs in age from place 

 to place according to the time taken by the advance 

 of this strand-line across intervening distances. 



Weather at Falmouth in 1922. — Falmouth 

 Observatory has recently issued meteorological notes 

 and tables for the year 1922, prepared by Mr. J. B. 

 Phillips, superintendent of the Observatory. The 

 mean barometric pressure for the year was 29-96 in., 

 which is 0-02 in. below the normal. The mercury 

 reached a maximum height of 3079 in. during 

 November, which is also the highest November 

 reading on record since the commencement of 

 observations in 1871. The high - pressure system 

 associated with this reading prevailed from November 

 10 until December 15. In July the barometer fell to 

 28-98 in., which is the only record with the barometer 

 below 29 in. in July. Temperature reached its 

 highest reading, 75° F., on May 31, and the minimum, 

 28° F., on March 23. The summer was cool, the 

 day temperature registering 70° F. or above on 6 

 days only, 4 in May and one in June and September 

 respectively. Bright sunshine for the year registered 

 1663 hours, which is 90 hours less than the normal ; the 

 brightest month was May with 260 hours of sunshine, 

 and the least sunny was December with 48 hours. 

 Rain fell on 211 days, yielding a total of 45-75 in., 

 which is 0-14 in. more than the normal. December, 

 which is normally the wettest month of the year, 

 had the highest monthly rainfall, amounting to 

 8-02 in., of which 7-64 in. fell in the last 16 days. 

 During the year the equability of the climate of 

 Falmouth withstood two severe tests. In an 

 exceptionally cold period at the beginning of April, 

 of 108 stations in the British Isles it was one of 

 9 at which the temperature did not fall below 34° F., 

 and during a hot spell from May 21 to 24, when 

 temperatures above 80° F. were general on the coast, 

 the maximum did not rise above 68° F. 



Commercial Production of Oxygen. — The 

 Chemical Trade Journal for June 15 contains an 

 account of a long paper by Mr. T. Campbell Finlayson 

 on " Industrial Oxygen," which was read before the 

 Institution of Chemical Engineers. The aim of the 

 work was to find a means of producing oxygen 

 industrially at a price of is. per 1000 cu. ft. This 

 was not realised, but a large number of possible 

 methods were tried, some of which were found to be 

 quite practicable. Chemical methods are impossible, 

 as they are invariably too expensive ; the most 

 promising method is based on the differential solubility 

 of oxygen and nitrogen under pressure in different 

 liquids. Mr. Finlayson remarked that the discovery 

 of a more suitable solvent might put the matter in 

 a very different light. It will be recalled that this 

 method was used, with water as a solvent, by Mallet 

 half a century ago. 



Recording Water - levels Electrically. — A 

 new form of electric transmission, for long-distance 

 indication of variations in water-level and similar 

 purposes, has been devised and put on the market 

 under the designation of the Telechron Transmitter. 

 The drawback in regard to systems of electric trans- 

 mission in such cases is that dependence has to be 



NO. 2805, VOL. I 12] 



placed on the unfailing action of the receiver to record 

 the series of impulses sent out from the transmitter. 

 With the ordmary electro - magnetic apparatus, 

 owing to difficulty in exciting the magnetic field 

 with sufficient promptitude, there is a possibility of 

 failure to transmit signals which succeed one another 

 rapidly. In other words, the receiver and trans- 

 mitter are liable to " get out of step." In the Tele- 

 chron instrument, signals are transmitted at a 

 constant rate, independent of the speed of movement 

 of the float or other actuating agent ; the impulses 

 are accumulated by the transmitter and are de- 

 spatched in sequence at a rate within the capacity 

 of the receiver to record them. It is thus possible 

 for a float to make a rapid rise without the omission 

 in the recorder of any one of the impulses in the 

 series generated. Falls in level are equally accounted 

 for, and when alternations take place rapidly the 

 instrument records the net difference in either sense. 

 It is possible to store up any number of impulses in 

 the transmitter, though for practical purposes it is 

 only necessary to provide for a hundred revolutions 

 of the counter. Should the circuit by any chance 

 be broken or the battery fail, the transmitter auto- 

 matically sets itself and the receiver in .step on the 

 restoration of the current. There are other possible 

 applications of the Telechron besides the long-distance 

 record of water-levels ; it is a trustworthy telegraph 

 to indicate the position of a ship's helm, or of a 

 lock-gate, or other moving object. It can also be 

 adapted to the purpose of recording the pressure 

 in gas mains. The apparatus is introduced by the 

 Telechron Electric Transmitter Company, of 53 

 Victoria Street, S.W. 



Luminescence. — Luminescence, as defined by 

 Wiedemann, includes all cases of radiation except 

 those due to temperature alone. In this sense the 

 term is used in the valuable report published as a 

 Bulletin of the National Research Council of the 

 United States, entitled, " Selected Topics in the Field 

 of Luminescence." The report, which is the work of 

 Prof. E. Merritt, E. L. Nichols, and C. D. Child, covers 

 a wide range, but most of the topics chosen for dis- 

 cussion are connected with fluorescence and phosphor- 

 escence. Prof. Merritt, who is responsible for the 

 greater part of the volume, contributes an important 

 chapter on theories of luminescence, dealing with the 

 work of Lenard, Kowalski, Kennard, Baly and Perrin. 

 A perusal of this chapter confirms the opinion that 

 the most important problem at the present time in 

 the field of luminescence is that of developing some 

 satisfactory and comprehensive theory which may 

 serve as an aid in correlating the observed phenomena 

 and as a guide in planning new investigations. Such 

 a theory must link together the varied subjects dealt 

 with in later chapters — luminescence at high tem- 

 peratures, luminescence and photo-activity, and, in 

 particular, fluorescence and chemical change. Special 

 attention may be directed to the work of Pringsheim, 

 who, after a somewhat extended discussion of photo- 

 chemical theories of fluorescence, is inclined to decide 

 against such theories, putting forward certain sug- 

 gestions in explanation of the chemical changes that 

 so often occur in connexion with fluorescence. In 

 the bibliography of luminescence, forming the last 

 chapter of the report. Dr. J. A. Becker has made a. 

 serious attempt to include references to all books and 

 articles on luminescence that have appeared between 

 the years 1906 and 1922. References to papers on 

 spectroscopic work have been included when, as in 

 the case of flame spectra, they appear to have a 

 direct bearing on the theory of luminescent radia- 

 tion. 



