158 TRANSACTIONS OF SECTION A. 



small but finite breadth, owing to 1 < a < 3. A few concrete examples are quoted, 

 together -with the distribution of the components and sub-components. If, say- 

 in the case of doublets, the frequency interval is to be such as that observed for 

 the doublet Ha, formula (1), with (2), gives for the distance of the centres 

 2a = 3.10-i2cm. 



In the next place, nuclei of any axially symmetric form are discussed and 

 shown to lead to essentially similar results. Finally, the most general case 

 of an arbitrarily shaped nucleus is investigated, when besides & also the 

 longitude of the node is shown to be a source of finite breadth of some of 

 the sub-components; moreover, formula (1) is in all such cases replaced by 

 a somewhat more complicated one. 



The full paper will shortly be published in the Philosopliical Magazine. 



3. The Beterminat'wn of the Viscosities of Liquids at Hiqli Pressures. 

 By Dr. T. E. Stanton, F.B.S. 



The method consists essentially of a system of two horizontal (the upper one 

 of oapillarvi dimensions) and two vertical tubes forming a closed circuit of 

 liquid under pressure, the lower half of the circuit containing mercury and the 

 upper half the liquid imder test. The end of the system rests on a horizontal 

 knife edge, and the other is carried by a spiral spring. On the mercury being 

 displaced by a given amount, flow will take place round the circuit owing to 

 the difference of head, and it is evident that if the spring be so designed that 

 its rate of extensions is equal to the rate of change of head of the mercury, flow 

 of the liquid under test will take place through the capillary tube under a 

 constant pre.ssure difference and at a velocity which can be calculated from 

 the rate of extension of the spring. In this way all the data required for the 

 determination of the absolute viscosity of the fluid are determined. 



4. Wireless Telegraphy during the First Three Years of the War. 

 "By Major T. Vincent Smith, M.C. 



This paper deals with wireless in what was the Military Wing of the Boyal 

 Flying Corps during the first three years of the war. and brings the history 

 of this work up to tlie time of the amalgamation of the 'Eoyal Naval Air Service 

 and Royal Flying Corps into the Royal Air Force. 



It shows the state of knowledge at the beginning of the war, and the 

 gradual progress made in the building up of an immense organisation. 



It gives in detail the experiences of the early days, the difficulties which 

 arose, and how they were met. 



Improvements in apparatus, methods, etc., and their effect upon operations 

 are shown, and the technical means by which the enemy was beaten are 

 discussed. 



The important w-ork of the E-oyal Flying Corps in co-operation with Artillery, 

 Infantry, and Cavalry would have been practically impossible without wire- 

 less. These things are discussed from their inception, and their progress followed 

 from birth to maturity. 



The introduction of thermionic values for transmission and reception, inter- 

 aeroplane telephony, and directional wireless are touched upon, though the war] 

 ended before their influence had time seriously to affect the final operations. 



The story is a collection of details, each one small in itself, but the com- 

 bined whole shows how the many difficulties, inseparable from an ever-increasing] 

 demand, were overcome in a manner which earned the respect of the enemy. 



5. The Limitations of Relativity. 

 By W. J. JoiiNRTON and Sir Joseph L.\rmor. 



The following propositions are believed to be valid, on the basis of a con- 

 cise symbolic calculus, subject, of course, to critical verification. 



(1) If a field of physical activity possesses the two characteristic properties 



