August 31, 19 16] 



NATURE 



541 



of mean velocity to velocity at the axis being avoided. 

 The formula for the displacement of the interference 

 fringes must henceforth be written with a factor 



<//, instead of the simple product "v^^.l. 



/ 



Final!}', the value of the ratio of the mean velocity to 

 the velocity at the axis may now be calculated. We 

 obtain 0-844. This number is not, however, a 

 physical constant, but a constant of my apparatus. 



Only quite recently have I become acquainted with 

 the extremely important and exhaustive work done at 

 the National Physical Laboratory, published by Drs. 

 Stanton and Pannell in their memoir on similarity 

 of motion in relation to the surface friction of fluids. 

 From their data I find for the often mentioned ratio 

 082, when the values of maximum velocity and 

 diameter of the tubes in my case are substituted. 

 Their observations were made, however, after the 

 passage of a length of pipe varying from 90 to 140 

 diameters, sufficient to enable any irregularities in 

 the distribution of the velocities to die away. In 

 my repetition of Fizeau's experiment this condition 

 was, of course, largely departed from, so that there 

 is no conflict between the results. 



Amsterdam, August. P. Zeeman. 



THE NEWCASTLE MEETING OF THE 

 BRITISH ASSOCIATION. 



JUDGING by the number of members who have 

 already intimated their intention to be present 

 at the meeting- of the British Association in New- 

 castle-upon-Tyne, which, as previously announced, 

 will open on Tuesday, September 5, and close on 

 Saturday, September 9, and taking into account 

 the numbers who have enrolled locally, an attend- 

 ance of about 1200 is expected. The intention 

 is to hold a purely business meeting — a meeting 

 in keeping with Newcastle in particular and the 

 world in general. 



The general title of the President's address, 

 which Sir Arthur Evans will deliver in the Town 

 Hall on the Tuesday evening, is "The Cradle of 

 European Civilisation." 



The work of the sections will commence on the 

 Wednesday morning-, and so far as can be ascer- 

 tained at present the following are the pro- 

 grammes : — 



Section .A (Mathematics and Physical Science). 

 The title of Prof. Whitehead's address to Sec- 

 tion A is "The Organisation of Thought." The 

 address is a brief examination of the nature of 

 scientific thought. The crude immediate experi- 

 ence of Nature is contrasted with the refined scien- 

 tific conceptions and with the exact deductions of 

 applied mathematics. The problem considered is, 

 "How do these two sides of scientific knowledge 

 fit together?" Two discussions have been 

 arranged, one on gravitation, to be opened by 

 Mr. E. Cunningham, and the other on osmotic 

 pressure, to be opened by Prof. A. W. Porter. 

 Papers to be read are :-^" The Partition of 

 Numbers," bv Major P. A. MacMahon; "The 

 Measurement 'of Time," by Prof. H. H. Turner; 

 "X-Ray Spectra of the Elements," by Sir E. 

 Rutherford. 



On the Friday of the meeting the section will 

 divide into departments of (a) General Physics, 



NO. 2444, VOL. 97] 



(b) Cosmical Physics, and (c) Mathematics. In (a) 

 Prof. VV^. M. Hicks will deal with "Can the Fre- 

 quencies of Spectral Lines be represented as a 

 Function of their Order? " Dr. R. T. Beatty is to 

 read a paper on " Measurement of the Energy in 

 Spectral Lines"; Prof. J. C. McLennan on " lon- 

 isation Potential " ; and Dr. S. Chapman on " The 

 Kinetic Theory of Gases." Communications to 

 Department (6) are " Efficiency of Sun-spots in rela- 

 tion to Terrestrial Magnetic Phenomena," by the 

 Rev. A. L. Cortie ; and the Report of the Seismo- 

 logy Committee. Department (c) is to consider : — 

 "Oscillating Asymptotic Series," by Prof. G. N. 

 Watson ; " Suggestions for the Practical Treat- 

 ment of the Standard Cubic Equation," by 

 Prof. R. W. Genese ; and " On a New Method for 

 the Solution of Quartic Equations," by Mr. P. 

 Burton. By way of explanation of the section 

 devoting its main attention to problems which may 

 seem remote from those especially in the nation's 

 thoughts at the present time, it is explained that 

 much of the work now being done by members of 

 the section is of a confidential nature, and that it 

 is considered undesirable to discuss such subjects 

 as, say, aviation or optical problems, on which it 

 would be impossible to speak freely without 

 indiscretion. 



In the presidential address to Section B 

 (Chemistry), Prof. G. G. Henderson proposes to 

 give a short account of the chief developments in 

 chemical technology during the last quarter of a 

 century, and then to deal with the future prospects 

 of the chemical industry in this country. The 

 papers to be read before Section B are: — "The 

 Future of the Organic Chemical Industry," by Mr. 

 F. H. Carr; "The Britisli Coal-tar Colour Industry 

 in Peace and War," by Mr. C. M. Whittaker; 

 "The Preparation of Chemicals for Laboratory 

 Use," by Mr. W. Rintoul ; several short papers on 

 iron and steel problems by Dr. J. E. Stead ; and 

 "On the Stepped Ignition of Gases," by Prof. 

 W. M. Thornton. There will be joint discussions 

 with Sections A, C, and G. 



In Section C (Geology) there will be papers read 

 on "Local Geology," by Prof. G. .A. Lebour; 

 " The Old Red Sandstone Rocks of Kiltorcan, Ire- 

 land," by Prof. T. Johnson; "Description of a 

 Plexc^raphic Model of the South Staffordshire 

 Thick Coal," by Mr. W. Wixham King; "The 

 Acid Rocks of Iceland," by Mr. Leonard Hawkes; 

 "The Petrology of the Arran Pilchstones," by Dr. 

 Alexander Scott; "The Carboniferous Succession 

 in North Cumberland," by Prof. E. J. Garwood ; 

 "The Permian of North England," by Dr. D. 

 Woolacott ; " Geological Characters of Glass 

 Sands," by Dr. P. G. H. Boswell; and "Some 

 Geological Aspects of Moulding Sands," by Dr. 

 Boswell. There is to be a joint meeting with 

 Section B on "Coal and Coal Seams, with Special 

 Reference to their Economic Uses." The section 

 will also hold joint meetings with Section E and 

 Section K. 



Prof. MacBride's address to Section D 

 (Zoology) will take the form of a review of our 

 progress during the last twenty years in elucidat- 



