422 



NATURE 



[November 25, 1920 



Developments of Wireless Communication. 



IN the course of his address to the Royal Society of 

 Arts on November 17, Mr. A. A. Campbell 

 Swinton, chairman of the council of the society, gave 

 a remarkable experimental demonstration of some of 

 the most recent developments in wireless telegraphy. 

 Utilising only a small aerial on the roof, where the 

 conditions were far from favourable, he commenced 

 by pidcing up some messages of a general news 

 nature which were being sent out by the 7000-metre 

 continuous-wave station of the Admiralty at Horsea, 

 near Portsmouth, about sixty miles from London. 

 These messages were first received by means of a 

 group of thermionic valves, and the clear-cut, distinct 

 Morse signals were rendered audible to the large 

 audience by a telephone receiver with a trumpet 

 attachment. 



A printing equipment of the pattern originally 

 developed by Mr. F. G. Creed for line telegraphy, but 

 now most successfully adapted to wireless working, 

 was then put into action under the supervision of 

 Mr. Creed himself, and the receiver was soon seen 

 to be punching a paper strip in accordance with the 

 Morse signals received. The strip was then put into 

 the printer, and appeared on another strip auto- 

 matically translated into ordinary type. A portion 

 of the printed strip was projected upon the screen, 

 and was seen to contain an extract from a speech 

 by Mr. Bonar Law, with but few errors due to jam- 

 niing or atmospherics. Between the experiments Mr. 

 Campbell Swinton found time to explain briefly the 

 way in which groups of thermionic valves connected 



in a particular way can be employed to detect and 

 to amplify the received oscillations, and, by the addi- 

 tion of an auxiliary oscillation, to produce signals at 

 a frequency audible in a telephone, by the method of 

 beats. He also recapitulated the leading principles 

 of the extraordinarily ingenious Creed receiving and 

 printing instruments by which the signals are recorded 

 in the Morse code and afterwards translated into 

 ordinary type by means which we hope to deal with 

 a little more fully later. The most impressive demon- 

 stration was the reception and printing of a special 

 message sent from the Eiffel Tower by the kindness of 

 Gen. Ferrie on the same apparatus, but with even more 

 success than in the case of the Horsea messages. 



Passing to wireless telephony, Mr. Campbell 

 Swinton attributed the earliest accomplishment erf 

 real wireless telephonic communication to Prof. 

 Poulsen, of Copenhagen, and showed diagrams of 

 the latest arrangement used by the Royal Air Force. 

 In conclusion, a special five-valve receiver, made for 

 the purpose by Mr. H. W. Sullivan, was put into 

 action, and the audience was entertained with some 

 spoken remarks, whistling, and gramophone music 

 from a short-wave installation in another part of 

 London. Mr. Campbell Swinton predicts great 

 developments in the field of wireless telephony, and 

 looks forward to the time when a speaker at a 

 political meeting will be able to make himself heard 

 all over the world, or it will be possible for the King 

 to address his subjects throughout hk Empire simul- 

 taneouslv. 



Engineering at the British Association. 



SIXTEEN papers w-ere read before Section G ; these 

 covered a wide field, but, with the exception of 

 Prof. Howe's paper on radio-telegraphy, electrical 

 engineering was entirely unrepresented. Several of 

 the papers were of great importance in that they 

 dealt with fundamental properties of materials and 

 of internal-combustion phenomena. Prof. F. C. Lea 

 read a paper on the effect of temperature on some 

 of the properties of materials. Many materials, such 

 as aluminium alloys, have highly desirable properties 

 when cold, but undergo such changes at the tempera- 

 tures met with in engine cylinders as to make them 

 quite unsuitable. Fireproof buildings must be de- 

 signed to have the requisite strength at temperatures 

 likely to be experienced during a fire. The tensile 

 strength and hardness of a large number of materials 

 have been determined at various temperatures ob- 

 tained by means of electric furnaces, details of which 

 were given. In all the alloys tested the tensile 

 strength and the hardness decrease as the tempera- 

 ture is raised, the decrease being very rapid between 

 200° and 400° C, which is a range likely to cover 

 both the examples mentioned above. Concrete was 

 among the materials tested on account of its import- 

 ance in view of the behaviour of ferro-concrete 

 buildings in case of fire. ' * 



Col. Crompton discussed the nature of the action 

 leading to the blunting of the edges of cutting-tools. 

 Without accurate knowledge of the nature of this 

 phenomenon one cannot scientificiilly re-design cutting- 

 tools when making them of the recently developed 

 high-speed steels containing, in addition to carbon, 

 such metals as tungsten, cobalt, molybdenum, nickel, 

 and vanadium. These steels can be hardened like 

 carbon steel, but, unlike it, they retain their hardness 

 at the high temperatures caused bv taking heavy 

 cuts at high speed. They are also stronger to resist 



NO. 2665, VOL. 106] 



fracture, and can thus be made with a more acute 

 angle. This angle varies from 90° in shears and 

 punches down to 15° in the blades of safety razors. 

 The smaller the angle the less is the force required 

 to drive the edge into the material, but the weaker 

 is the edge to resist breakage. If examined under a 

 microscope the edge is seen to be blunted by the 

 crumbling away of the material of which the tool 

 is made. This crumbling is hastened by the shaving 

 wearing a groove in the upper face of the tool, thus 

 reducing the angle of the edge. The author was of 

 opinion that all the ordinary tool angles could be 

 reduced 25 per cent, when using high-speed steels. 



It is not often that a paper is read before Section G 

 by an author who speaks, not as an engineer, but as 

 a critical user of the engineer's products. Mr. S. F. 

 ■Edge's paper on farm tractors made one realise the im- 

 portance of such communications. Mr. Edge evidently 

 spoke from a wide experience of tractors of many 

 types, and discussed them not only from the engineer- 

 ing and agricultural points of view, but also from that 

 of their psychological effect on the labour question. 

 He warned makers against sacrificing quality to 

 cheapness, and expressed his belief in the future of 

 the tractor industrv if makers will give the farmers 

 the best machines alike in design, material, and work- 

 manship. 



Mr. H. R. Ricardo's paper on a high-speed internal- 

 combustion engine for research dealt with experi- 

 ments carried out with an engine speciallv designed 

 for fuel research at the request of the .\siatic 

 Petroleum Co. Nothing had been spared to make the 

 experiments trustworthv and exhaustive and of both 

 scientific and commercial value. The author described 

 the design and construction of the engine in detail, 

 together with the arrangements for measuring the 

 fuel supply, etc. With this engine one will be able 



