April 



:)y 



I9I7] 



NATURE 



1 1 



of the S. temperate belt, and the intervening zone 

 between it and the N. tiopical belt was occupied by a 

 remarkable series of bright elliptical formations, 

 usually accompanied by dark condensations on the 

 south preceding side. These elliptical forms appear 

 on all the photographs taken during 19 16, and are 

 probably to be interpreted as representing cyclones. 



THE INSTITUTION OF NAVAL 

 ARCHITECTS 



THE spring meetings of the Institution of Naval 

 Architects were held in the rooms of the Royal 

 :iety of Arts on March 28 and 29. In the unavoid- 

 le absence of the president — the Earl of Durham — 

 ;:ie Marquis of Bristol took the chair and delivered 

 an address, in which he referred to the question of the 

 formation of a council for co-ordinating the common 

 interests of the various institutions representing en- 

 gineering professions. Such a council, in making 

 recommendations, would have the weight of the whole 

 profession behind it. 



The Elgin scholarship has been awarded to Mr. R. J. 

 Shepherd, and the annual gold medal to Prof. T. B. 

 Abell for his paper on experiments to determine the 

 resistance of bilge keels to rolling. A premium has been 

 awarded to Mr. A. T. VVa'l for his paper on some 

 effects of the Bulkhead Committee's report in practice. 

 Despite the disadvantages under which the institu- 

 tion has been placed owing to so many of its members 

 being engaged on work intimately connected with the 

 war, thirteen papers were read and discussed. The 

 standard of the papers has in no way diminished, and 

 man\' contain matter of considerable scientific interest. 

 Mr. D. B. Morison's paper on standardisation as 

 applied to the machinery for cargo-boats is of much 

 interest at the present time, when a strong effort is 

 being made to make good losses due to piratical sub- 

 marine operations. A specification for such machinery 

 is being discussed now by the North-East Coast In- 

 stitution, and an appeal was made for joint action by 

 all the institutions connected with shipbuilding. An 

 interesting feature of Mr. Morison's paper is the many 

 references to economic problems. It is futile for 

 capital to expect that labour will consent to any great 

 reduction in wages, and equally hopeless for labour to 

 expect the maintenance of the present high rate of 

 wages without concession on its part. To render it 

 possible to pay high wages in the future and yet 

 maintain our trade, the requisites are (i) a candid 

 acknowledgment by labour of the economic law that 

 good general trade is dependent on maximum pro- 

 duction, and (ii) capital must recognise that maximum 

 production entails correspondingly high pay. 



Mr. J. Montgomerle contributed a valuable paper 

 giving an account of experiments conducted at the West 

 Ham Technical Institute on stress determination in a 

 fiat plate. In these exoeriments the plates were bolted 

 in a vent' heavy frame, rectangular in plan, leaving a 

 surface of plate measuring 4 ft. by 2 ft. exposed to 

 water-pressure. The object was to hold the plate 

 round the edges as rigidly as possible. Bach's plates — 

 which constitute the only experimental work on the 

 large scale up to tnt present — were not held so rigidly 

 at the edges. Crawford's experiments on the same 

 subject were on too small a scale. Mr. Montgomerie 

 has experimented on several plates of various thick- 

 nesses; the plate 075 in. thick alone is reported upon 

 in the paper, although the exf>eriments on the other 

 plates have been completed. 



Measurements of deflection were made at many 

 stations on the plate, and curves plotted showing the 

 cross-sections in directions parallel to the edges. From 

 these curves, by application of graphical methods, the 

 stresses at the statio-s were determined. Owing to 

 NO. 2475, VOL. 99] 



the nature of the graphical methods employed, it was 

 considered desirable that the strains in the plate should 

 be measured directly, and for this purpose a strain- 

 meter was devised by Mr. J. Duncan and used in such 

 a manner as to determine the principal axes of strain 

 at the stations. The principal strains were then 

 measured at each station, and from the knowledge 

 thus obtained, together with the measured values of 

 Young's modulus and Poisson's ratio for the material, 

 the principal stresses were determined and the ellipses 

 of stress drawn for each station. The results by 

 these two methods show very fair agreement. 



The resulting diagram is very interesting, and shows 

 the elastic behaviour of the entire plate. It shows that 

 the maximum stress actually occurs at the centre of 

 the plate and not at the frame ends of the short 

 diameter, as has been supp>osed hitherto. There is no 

 doubt that this fact is di'.e to the elastic movements of 

 the portion of the plate clamped in the frame, which 

 permit the "wall secti-)n " to assume slope instead of 

 remaining in the plane of the wall, as is assumed in 

 the usual mathemati ;al theory Tht effect of this 

 behaviour is to diminish the bending moment at the 

 plate edges and to increase that at the centre; the 

 stresses, of course, alter correspondingly. Mr. 

 Montgomerie has promised further information re- 

 garding the other thinner plates tested, and his con- 

 tribution must be regarded as a valuable addition to 

 our knowledge of cases of complex stresses. 



Mr. Thomas Graham described an apparatus for 

 interpreting stability for the use of shipmasters, 

 whereby the stability of vessels under any ordinary 

 conditions of loading can be shown graphically and 

 easily interpreted. This instrument illustrates three 

 features of stability which are of most practical im- 

 portance, viz. : — (i) An automatic record of the varia- 

 tion of the righting arm as the ship heels over from 

 the upright to the vanishing angle, (ii) The approxi- 

 mate angle of heel at which the freeboard deck edge 

 becomes awash, (iii) The position of the water-line 

 throughout the range of moderate angles met with in 

 practice. The appliance consists of a pivoted wooden 

 lamina representing a cross-section of the ship, and 

 having a pointer moving over a protractor showing 

 angles of heel. A plumb line is hung from the posi- 

 tion on the lamina corresponding to the known centre 

 of gravity of the ship. A brass plate having a curved 

 edge representing the metacentric evolute for the given 

 draught and displacement is attached to the lamina, 

 and another plumb line is arranged to pass over the 

 edge of this evolute and to hang tangentially. The 

 distance between the wo plumb lines thus shows to 

 scale the magnitude of the actual righting lever at all 

 angles of heel. An additional feature is an arrange- 

 ment for indicating the position of the water-line. 



Prof. W. E. Daiby read a paper illustrating the 

 inner structure of mild steel, and showing how its 

 strength is correlated with this inner structure. This 

 paper is one of the most readable produced up to date, 

 and contains explanations which can be followed 

 readily by reference to the many micrographs in- 

 cluded. Load extension diagrams of all the steels 

 have been obtained by use of the author's well-known 

 apparatus. 



Lieut. Walter A. Sooble contributed a paper on the 

 design of pin joints based on ultimate strength. The 

 author gives reasons leadmg to the conclusion that the 

 maximum load carried is the best criterion for the 

 strength of a pin joint, and describes in detail a method 

 by which the calculations required in designing a joint 

 can be made. 



Mr. J. J. King-Salter gave an account of some ex- 

 periments on the inflrence of runnings balance of pro- 

 pellers on the vibration of ships. Since the introduc- 

 tion of turbines in warships, running at a much higher 



