April 20, 1905] 



NA TURE 



595 



A paper on a similar subject was read by Mr. F. H. 

 Alexander. 



A long and elaborate paper, illustrated by numerous 

 diagrams, was next taken. The subject was the structural 

 arrangements of ships, the author being JMr. J. Bruhn. 

 Details of tests of frame girders, on the strength of flanged 

 plates, on intercostal stringers, on the tripping of frames, 

 and the strength of rivet attachments, were described. 

 The paper was of considerable professional interest, and 

 will form a valuable source of information to naval archi- 

 tects ; but without the aid of the numerous illustrations 

 and diagrams it would be impossible to make the descrip- 

 tions clear. 



Kl the evening meeting of the same day a paper by 

 Mr. R. E. Froude on hollow -versus straight lines opened 

 the proceedings. The subject has attracted a good deal of 

 interest of late, and has already led to some discussion. 

 K number of naval officers, led by Admiral Fitzgerald, 

 hold that a great mistake is made by building ships for 

 the Royal Navy with hollow lines. Sir William White 

 and the other naval constructors naturally defend their 

 practice, supporting their arguments by the actual results 

 obtained at the Haslar tank. The naval men reply that, 

 even allowing the superiority of hollow lines in the smooth 

 water, at which all tank experiments were made, the 

 hollow lines gave a slower vessel amongst waves, and 

 also a wetter ship. In order to bring the matter to a 

 practical issue, a number of experiments were made by 

 Mr. Froude at the Haslar tank, in which artificial waves 

 were created by a mechanical device. The results were 

 plotted on diagrams attached to the paper, the general 

 conclusion arrived at by Mr. Froude being that though 

 there was a distinct diminution in average effective horse- 

 power due to straight lines, yet this was insufficient to 

 annul the greater efficiency of the hollow lines in smooth 

 water. In the discussion that followed, Admiral Fitz- 

 gerald joined issue on this point. He held that quite 

 smooth water was comparatively rarely met with at sea, 

 and he considered it was a question for naval officers, and 

 not for naval architects, to decide under which condition 

 they would prefer the higher efficiency. Moreover, the 

 straight lines gave greater displacement forward without 

 extra cost, and the additional buoyancy could be used for 

 placing heavier guns forward, or in other useful ways. 

 Prof. Biles also joined in the discussion. He gave the 

 results of trials on this subject made at the Dumbarton 

 tank. These results were in contradiction to those given 

 in Mr. Froude's paper, and until this discrepancy is ex- 

 plained the subject must remain unsettled. The need for 

 an independent tank devoted to experimental investigation 

 is apparent. Mr. Froude's experiments are extremely 

 interesting, as being the first tank trials made in other 

 than smooth water. When it is remembered how little 

 smooth water there is at sea, and how widely the con- 

 ditions of resistance and other qualities are altered by 

 waves, the advantage of the new departure will be 

 apparent. 



An interesting paper by Mr. A. W. Johns, of the Royal 

 Corps of Naval Constructors, was also read at this 

 sitting, the subject being the effect of motion ahead on 

 the rolling of ships. The subject is one both of interest 

 and importance, and was worked out by the author with 

 considerable ingenuity, theoretical results being compared, 

 with those obtained by experiment. It would appear that 

 the effect of speed is to reduce rolling, but no doubt further 

 tests will be made, the actual experimental data up to now 

 being somewhat meagre. 



Mr. Stromeyer also read a paper on the effect of acceler- 

 ation on ship resistance. 



Another paper was down for reading at this sitting, 

 but unfortunately time did not permit of it being read. 

 It was by Mr. S. Popper, of Pola, the subject being the 

 results of model experiments in deep and in shallow 

 water. The subject is one of considerable practical im- 

 portance at the present time, when builders of destroyers 

 in the south find it pays them to send their vessels to the 

 measured mile on the Clyde, where there is deep water. 

 They find the Clyde mile permits of a knot more being 

 made than can be obtained on any of the comparatively 

 shallow miles of the south. 



On Friday, April 14, five papers were taken. Mr. 



NO. I 85 I, VOL. 71] 



A. E. Seaton contributed the first, the subject being 

 margins and factors of safety and their influence on marine 

 designs. Mr. J. H. Heck followed with some notes on 

 the variation of angular velocity in the shafting of marine 

 engines ; and Mr. Mallock read a brief paper in which 

 he described an ingenious device for keeping the two sets 

 of engines of a twin screw vessel out of step, so as to 

 prevent vibration. Mr. Attwood also read a paper on the 

 Admiralty course of study for the training of naval 

 architects. 



Perhaps the most interesting paper of the meeting was 

 that which came last. It was by Mr. J. B. Millet, of 

 Boston, Massachusetts, and described a means of sub- 

 marine signalling by sound, of which more will probably 

 be heard in the future. Briefly it may be said that the 

 sides of the ship itself are used as receivers. A tank 

 filled with a dense liquid is attached to each side of the 

 ship. In this a transmitter is placed, and the sound 

 collected is taken by wires to an observer, who may be 

 in any part of the vessel. If the source of sound is on 

 the port side the sound will be apparent from the port 

 transmitter ; if on the starboard side the starboard trans- 

 mitter will be affected ; if it is directly ahead it will be 

 heard equally through both transmitters. When the sound 

 is astern a different effect is produced. As the result of 

 practical trials, the positions of passing ships and of sub- 

 marine bells were accurately defined. When it is remem- 

 bered how untrustworthy sound signals are when passed 

 through air, and how unchanging is the density of water, 

 it will be seen that the new system promises to reduce the 

 chief dangers of modern navigation, collisions, or strand- 

 ings through fog. The idea of submarine sound signals, 

 of course, is not new, but the hitherto insuperable difficulty 

 in the way has been the confusion of sound through the 

 overwhelming nature of the noises in the ship itself. Mr. 

 Millet, however, appears to have overcome this difficulty, 

 and the testimony as to the value of his invention is very 

 strong. 



The meeting was brought to a conclusion by the usual 

 votes of thanks. 



UNSOLVED PROBLEMS IN ELECTRICAL 

 ENGINEERING. 



C\^ April 10 Colonel R. E. Crompton delivered the 

 ^^ annual " James Forrest " lecture of the Institution 

 of Civil Engineers, an abstract of which is given below. 



There are two groups of electrical problems, those which 

 concern the scientific investigator and those presenting 

 themselves to engineers. The lecturer dealt with the latter 

 only. The phenomena of lightning discharges, especially 

 where they affect the distribution systems of large electric 

 power plants, require further study. Many failures are due 

 to causes which the lecturer believes to be static dis- 

 charges due to gigantic condenser effects set up in systems 

 of well insulated overhead and underground conductors, 

 each system acting as a plate of the condenser. 



Interesting problems arise out of terrestrial magnetism ; 

 the present hypotheses are based on scant knowledge. It 

 is known that the earth's magnetic field is not symmetrical, 

 but the work of observing the variations of the earth's 

 field at public observatories all over the world may even- 

 tually enable the earth's field gradually to be plotted out. 



Another problem passing into the domain of engineering 

 is the etheric transmission of power. What is now required 

 is a better solution of the problem of producing continuous 

 trains of Hertzian waves either by mechanical means or by 

 electrochemical means. 



The lecturer dealt rather fully with what he called the 

 " core and coil " problem of electrical machinery, that is 

 to say, the problems connected with the perfecting of the 

 cores, hitherto of iron, but which in future may be made 

 of some of the alloys invented by Dr. Huesler, which 

 are now under test. 



Dealing with the present means of using iron or steel 

 castings of high permeability, the best methods were dis- 

 cussed of freeing them from blow-holes or porosity to 

 ensure that the magnet cores should be of equal density 

 of mass, and therefore of equal magnetic moment. In this 

 connection the lecturer alluded to Prof. Barrett's discovery of 



