30 



NATURE 



[September 2^ 1920 



Our Astronomical Column. 



Liverpool University Tidal Institute.— The first 

 annual report of this institute, established in 1919 

 with funds provided by Sir Alfred and Mr. Charles 

 Booth, gives a brief and interesting account of the 

 work so far taken up under the auspices of Prof. J. 

 Proudman, the honorary director, and Dr. A. T. 

 Doodson, the secretary. Besides theoretical work on 

 the seiches in Lake Geneva and on the dynamical 

 equations of the tides, the study of tide-prediction has 

 been vigorously prosecuted. The official British and 

 American predictions of the tides in the Mersey, cal- 

 culated by machines of Lord Kelvin's type on the 

 basis of analyses made many years ago by a com- 

 mittee of the British Association, often differ by a 

 foot in height between themselves, and from the actual 

 observed heights by amounts up to 3 ft. Dr. Doodson 

 finds that the predicting machines are susceptible to 

 error, though further examination is necessary to 

 determine whether to an extent which unfits them 

 for use in research. Meanwhile, the institute has 

 embarked on an intensive study of the tides at 

 Newlvn, near Land's End, from the oontinuous record 

 taken by the Ordnance Survey. This work has also 

 been assisted financially and otherwise by a British 

 Association committee. Analysis has been made by 

 computations on a novel plan ; the five most important 

 constituents in the tides were first removed, using 

 approximate values inferred from the results of 

 analvses for neighbouring stations. This reduced the 

 range from 18-5 ft. to 2-5 ft., and disclosed the 

 presence of quarter-diurnal constituents, which also 

 were removed bv a method suggested by theoretical 

 considerations. This revealed constituents of higher 

 orders and the presence of some unremoved semi- 

 diurnal constituents, as was to be anticipated. By 

 this method the real constituents are discovered, and 

 these alone removed. 



Longitude by Aeroplane. — The Comptes rendus of 

 the Paris Academv of Sciences for August 2 contains 

 a paper by M. Paul Ditisheim describing a new deter- 

 mination of the Paris-Greenwich longitude by the 

 repeated transfer of a series of chronometer watches 

 between the two observatories by an aeroplane. 

 Twelve watches were used which had previously been 

 tested at Teddington with most satisfactory results. 

 They were packed in wooden cases surrounded by 

 layers of wool, and remained in a horizontal position 

 during transit. They were compared with the 

 standard clocks at Greenwich and Paris by Mi;. 

 Bowyer and M. Lancelin respectively. The average 

 time' of transit was 2| hours ; on one occasion the 

 double journey v,'as completed on the same day. 



The resulting longitude difference is 9m. 20-947s., 

 with a probable error of 0027s. It is only ooo^s. 

 less than the mean of the British and French results 

 in the 1902 determination. It is needless to say that 

 the new value does not claim anything like so much 

 weight as that of 1902, in which the observers were 

 exchanged and personal equation was eliminated. It 

 is, however, an interesting' confirmation of it, and it 

 illustrates the fact, already known, that the use of the 

 travelling wire in observing transits greatly diminishes 

 personal differences. This fact gives ground for hope 

 that the method of wireless signals, without^ inter- 

 change of observers, will give close approximations to 

 the longitudes of all the participating observatories. 



Observations with the Photo-Electrtc Cell. — 

 Prof. Joel Stebbins's valuable pioneer work with the 

 selenium cell (with which he discovered the secondary 

 minimum of Algol) is now being continued with still 

 greater refinement with the photo-electric cell. The 



Astrophysical Jourtud for May contains two of his 

 researches. The first is on the Algol-variable A,'Iaun. 

 The light-curve much resembles that of Algol, a 

 secondary minimum being shown here also. Elements 

 are deduced from Prof. Stebbins's results combined with 

 the spectroscopic ones. The masses of the two stars are 

 2-5 and 10 times that of the sun ; the radu are 48 and 

 •j-6 times the sun's; and a third body is suspected with 

 mass 0-4. The side of the secondary that is turned 

 towards the primary is much brighter than the other, 

 which is ascribed to the intense radiation of the 



primary. . ^ . . .,-.. 



The other star examined is v' Ononis. The varia- 

 bility was detected before Prof. Stebbins noted that 

 it had already been classified by Lee as a spectroscopic 

 binary (with only one visible spectrum). The total 

 range of light is only 006 magnitude, yet the observa- 

 tions suffice to give a consistent curve. As this proves 

 to be a sine-curve with two periods in the time of 

 revolution, it is concluded that the light-variation does 

 not arise from eclipse, but from the spheroidal figure 

 of the bright component. The ratio of axes is 0-95, 

 which is quite a reasonable figure. 



Prof. Stebbins states that he has at last succeeded 

 in obtaining a potassium cell, with walls of fused 

 quartz, that gives complete satisfaction. It was only 

 after ninety-eight trials that this result was reached. 



The Scientific Investigation of the Ocean. 



Need for a New •Challenger" Expedition. 



THE outstanding feature of the proceedings of 

 Section D (Zoology) at the meeting of the 

 British Association at Cardiff was the discussion on 

 August 26 on the need for the scientific investigation 

 of the ocean. 



In opening the discussion. Prof. W. A. Herdman, 

 president of the Association, pointed out that this need 

 may be considered under two heads— th,e scientific 

 need and the industrial. Simply as a matter oi 

 advancing knowledge, the need for much further in- 

 vestigation of the ocean is very great indeed, and 

 biologists realise that the industries connected with 

 those marine animals— fishes and others— which are 

 of economic importance are all of them badly in need 

 of scientific investigation. There is not a single 

 marine animal in regard to which it can be said that 

 we know anything like all there is to be known 

 and fully understand its mode of life. Even our 

 commonest fishes, such as the herring and the cod, 

 are in some respects unknown and mysterious to us. 

 Prof. Herdman then proceeded to give a few examples 

 of the need for further investigation. 



The first report of the Tidal Institute of the 

 University of Liverpool, issued a few weeks ago, 

 shows that the two independent published predictions 

 of the Liverpool tides— one issued by the Admiralty 

 and the other by the United States Coast and 

 Geodetic Survey—'' seldom agree ; they often differ by 

 a foot in height ; also, both of them sometimes differ 

 from the actual tide bv as much as 3 ft. in 

 height." It is evident from this report that the 

 present state of affairs urgently calls for more scientific 

 research both in regard to the theory of the tides and 

 to the accuracy of observations. _ 



The work of the bio-chemist and of the physical 

 chemist in connection with hydrography seems likely 

 to be of fundamental importance, e.g. the possibility 

 of determining the point of entrance to known cur- 

 rents of water bv means of indicators showmg the 

 hvdrogen-ion concentration mav be of practical utility 

 to navigators. Then asjain. Otto Pettersson's sub- 

 marine waves in the Gullmar Fjord and elsewhere. 



NO. 2653, VOL. 106] 



