170 



NATURE 



[April 20, 19 16 



ciated as it is with a spectrum of early, though some- 

 what peculiar, type, has an important significance in 

 relation to some of the suggested explanations of the 

 tardy motions of isolated helium stars. 



THE INSTITUTION OF NAVAL 

 ARCHITECTS, - 



nr*HE spring meetings of the Institution of Naval 

 •*• Architects were held on April 12 and 13, at the 

 Royal Society of Arts. The Marquis of Bristol's term 

 of office as president has now expired, and he has been 

 succeeded by the Earl of Durham. The institution 

 scholarship has been awarded to Mr. T. S. D. Collins ; 

 a donation of looi. has been made to the scholarship 

 fund by the Earl of Durham; the annual gold medal 

 has been awarded to Mr. A. W. Johns, and the pre- 

 mium to Mr. J. L. Kent, for papers read before the 

 institution. The following members of the institution 

 have been appointed to the Board of Trade Committee 

 to consider the position of shipping and shipbuilding 

 industries after the war : — Sir A. A. Booth (chairman). 

 Sir Archibald Denny, Mr. W. S. Abeli, and Mr. James 

 Readhead. A presentation was made to the retiring 

 president. 



In the course of the Earl of Durham's address, he 

 said that one paramount duty was before the whole 

 nation— to prosecute the war until a satisfactory end 

 was reached. Our naval architects had no better pride 

 than to turn out everything destined for the Navy of 

 the best possible quality. When the end of the war 

 came he felt sure that the institution would be able to 

 claim having done its share in the work. 



Sir Philip Watts read a paper on the load lines of 

 merchant ships, and the work of the Load Line Com- 

 mittee (1915). This paper consists largely of a his- 

 torical summary, starting with the earliest recorded 

 regulation, which appeared in Lloyd's Register book in 

 1774. The remainder of the paper gives the gist of the 

 report of the Load Line Committee, presented in a 

 form convenient for the purposes of the institution. 

 Mr. W. S. Abell followed with a paper on some ques- 

 tions in connection with the work of the Load Line 

 Committee. The question principally discussed is the 

 formulation of a suitable standard of structural 

 strength which might be adopted internationally for 

 the necessary tests which it is desirable to lay down 

 in order that the freeboard assigned shall not be so 

 small as to bring undue strains upon the structure of a 

 vessel. The rules of the registration societies have 

 been developed from experience, and should form the 

 basis of any analysis having for its object a general 

 average of experience with ship structures at sea. The 

 method adopted was to analyse the rules of the prin- 

 cipal societies in terms of \jy, and the principal 

 dimensions of the vessel with the view of obtaining a 

 standard of longitudinal strength which would express 

 rationally the minimum requirements found necessary 

 from successful sea experience. In this way formulae 

 were found for the standard of longitudinal strength, 

 the thickness of side plating, frame spacing, and the 

 strength of hold frames. This paper is a valuable 

 summary of some interesting work on the strength of 

 ship structures. 



Dr. C. H. Lees read a paper on the laws of skin 

 friction of a fluid in stream line and in turbulent 

 motion along a solid of great length. In this paper 

 Dr. Lees shows how to reduce the problem of a very 

 long body of rectangular or elliptic section towed along 

 a wide tube filled with liquid, to the simpler problem 

 of a long circular cylinder towed along the same wide 

 tube, so long as the liquid moving past the body is in 

 stream-line motion. Comparison of results calculated 

 for the equivalent cylinder and Froude's boards shows 



NO. 2425, VOL. 97] 



very fair agreement for the last 34 ft. of the boards. 

 The agreement is sufficiently close to show that there 

 is in all probability an intimate connection between the 

 frictional resistance of the after portion of a long 

 towed body and that of water flowing through a pipe. 

 It seems desirable that experiments should be made 

 with the view of determining to what extent the pro- 

 positions with regard to bodies of equivalent resistance 

 in stream-line motion may be carried over to eddying 

 motion, and, if it should prove they cannot be, to 

 determine the corresponding propositions for eddying 

 motion. 



Mr. G. S. Baker contributed a paper on the skin 

 friction resistance of ships, and our useful knowledge 

 of the subject. The data for the friction of rough 

 surfaces have been increased very considerably in the 

 last few years. Most of the data are derived from 

 model experiments, but in some cases authentic data 

 for ships are available. One model of fine form, 16 ft. 

 in length, tested in the National Tank, showed that 

 plate edges increased the frictional resistance 37 per 

 cent. The plates on the model represented 4-ft. 

 strakes of |-in. plating on a 400-ft. ship. A plate, 

 20 ft. by 2 ft., tested in the Washington tank after 

 immersion in Chesapeake Bay for two months (Julv 

 and August, 19 14) showed an increase in resistance 

 over that of a smooth surface of about 50 per cent. 

 The fouling and resistance went on increasing up to 

 the month of December, when the resistance stood at 

 about 220 per cent, increase over that for a smooth 

 surface, and remained at that figure for some months. 

 This suggests that a good time for cleaning and 

 painting the bottoms of coasting ships, working at 

 about this latitude, is October and November, as 

 there Is little growth in cold water for the next 

 few months. Presumably there would be a 

 period about. May and June when the temperature 

 had reached a point favourable for growth, when a 

 new" coat of paint would prevent the adhesion of 

 growth to the surface. 



In a paper on the subdivision of merchant vessels 

 and the Reports of the Bulkhead Committer, 1912-15, 

 Sir Archibald Denny suggests that, after the war is 

 over, an interesting paper might be written dealing 

 with the mass of information which will no doubt be 

 available as to the behaviour of vessels damaged 

 either sufficiently or Insufficiently to sink them. It 

 is interesting to know that many vessels have survived 

 torpedo and mine attack, even when the damage was 

 of a very extensive character. Thus the Nigretia 

 struck a mine abaft the fore peak, and had a hole 

 40 ft. by 16 ft. blown In her, but she was saved by 

 No. 2 bulkhead. The Germans also have not always 

 realised the difficulty of sinking an oil-carrier, esped-, 

 ally If she Is running light — vide the Artemis. The] 

 tests made by the Bulkhead Committee on large tank 

 bulkheads are described in a paper bv Mr. J. Foster 

 King. Drawings showing the deflection records and 

 photographs of the bulkheads are Included. In all, 

 fourteen papers were read and discussed. 



DANISH LABOUR ON BRITISH FARMS. 



THE Board of Agriculture proposes to relieve the 

 present shortage of labour on the farm by arrang- 

 ing for the introduction of agricultural workers from 

 Denmark. In this connection attention may be 

 directed to an exceptionally interesting article by Mr. 

 J. Robertson Scott in the January number of the ! 

 Quarterly Review. 



The wonderful development of rural life in Denmark 

 is largely due to the absence of coal and Iron. Having 

 practically no manufacturing industries, the Danes ; 



