no 



NATURE 



[March 24, 1910 



amount of work has been done towards setting up sub- 

 standards for use in measurements of metallic filament 

 lamps. The determination of the candle-power of these 

 in terms of the pentane standard involves a comparison 

 between lights of different colour, and in the process of 

 stepping up as many observers as possible must be 

 employed to obtain a representative mean. 



Early in the past year an agreement was arrived at 

 ^between the authorities in America, France, and this 

 •country as to a common light unit, the American unit 

 ^being altered by i-6 per cent, to bring it into agreement 

 •with the British unit expressed in terms of the lo-candle 

 Harcourt pentane lamp. 



In the thermometry division the work has consisted in 

 great measure of improvements in the equipment, especially 

 with the view of the extension of the work on the funda- 

 mental gas scale to higher temperatures. It is hoped 

 that a useful material for gas-tight vessels has been 

 -obtained, but further progress required power for heating 

 larger furnaces, which has now been provided. 



In the metrology division an interesting experiment is 

 being tried in the use of silica as a material for standards 

 of length. The advantages are a low coefficient of ex- 

 pansion and small thermal hysteresis, i.e. the temporary 

 change in length due to a cycle of temperature change is 

 small. A standard has been constructed with flat and 

 parallel end slabs fused into a hollow cylindrical rod, the 

 •slabs being platinised to receive the divisions. The study 

 of this standard will be continued during the present year. 



Important additions have been made to the sets of 

 standard screw gauges in the possession of the laboratory. 

 These now comprise complete series of British standard 

 Whitworth threads, British standard fine threads, British 

 standard electrical conduit gauges, and B.A. threads. 

 They have been constructed by Armstrong, Whitworth 

 and Co. to the dimensions laid down by the Engineering 

 Standards Committee. Two large machines for pitch and 

 diameter measurements are also being constructed at 

 Openshaw. 



The 50-metre mural base for verification of surveying 

 tapes has been completed. The length of this base is 

 stepped out against a 4-metre standard bar, itself deter- 

 mined against the standard metre. Another important 

 piece of work has been the re-erection of the Blythswood 

 ruling machine for puling diffraction gratings. By shift- 

 ing the periodic error connecting cam from one end of the 

 screw to the other, the length of grating which can be 

 ruled has been increased from 5 to 8 inches. The exact 

 setting of the periodic error cam alone remains to be done 

 to enable the ruling of gratings to be commenced. 



A useful piece of work in the optics division has been 

 the devising of a new apparatus for testing photographic 

 shutters. The method is essentially that of Sir Wm. 

 Abney, with the use of a vibration galvanometer in place 

 of a siren as a time recorder. 



In the engineering department a large number of re- 

 searches are in progress. Dr. Stanton is continuing his 

 wind-pressure work, as well as the research on the resist- 

 ance of materials to alternating stresses of high frequency. 

 Some very interesting results have been obtained with 

 regard to the heat transmission and friction of air currents 

 in pipes, and a paper on the resistance of plates and models 

 in a uniform current of water was communicated to the 

 Institution of Naval Architects. The water channel used 

 for these experiments has been utilised also for work in 

 connection with aeronautics, and gives results closely com- 

 parable with those obtained in an air channel, allowance, 

 of course, being made for the difference in density. A 

 valuable paper by Mr. Bairstow on the elastic limits of 

 material under alternating stress has been published in 

 the Philosophical Transactions, and contains interesting 

 experimental conclusions relative to the theory of fatigue. 

 Another research of importance which is in progress relates 

 to the strength and efficiency of welded joints, from which 

 the preliminary conclusions have been reached that the 

 material at a welded joint is often in a dangerously brittle 

 state, and that a long weld is essential to secure even 

 moderately good results. 



In ^ the department of metallurgy and metallurgical 

 chemistry, the work done for the Alloys Research Com- 

 tnittee of the Institution of Mechanical Engineers was 



NO. 2108, VOL. 83] 



embodied in the ninth report, on some alloys of copper, 

 aluminium, and manganese, presented to the institution 

 early^ in 1909. Further work on the light alloys of 

 aluminium is in progress. The eutectics research, on 

 which a first communication appeared in 1908 in the 

 Philosophical Transactions, has been continued, attention 

 being especially directed to the mode of solidification of 

 eutectic alloys. A preliminary account of an investiga- 

 tion into the effects of strain at high temperatures, recently 

 published in the Proceedings of the Royal Society, presents 

 features of interest. It was established that deformation 

 by intra-crystalline slip occurs at temperatures up to 

 1100° C, while the three allotropic modifications of iron 

 known as a, )3, and 7 iron showed marked differences in 

 the effects of strain. A number of cases of failure in 

 practice have been investigated, and in connection with 

 these a systematic study is being made of the modes of 

 fracture of steel. 



The work of the observatory departments of the labora- 

 tory, at Kew and Eskdalemuir, is of a distinct character, 

 and need not be referred to now in detail. Mention must, 

 however, be made of the admirable piece of work com- 

 pleted by Dr. Chree, in the discussion of the magnetic 

 curves of the National Antarctic Expedition of 1902-4, 

 printed in the volume of " Magnetic Observations " issued 

 by the Royal Society early last year. 



INSTITUTION OF NAVAL ARCHITECTS. 



'T'HE spring meetings of the Institution of Naval 

 Architects commenced on Wednesday, March 16, in 

 the rooms of the Royal Society of Arts. The institution 

 has now completed its first fifty years of existence, and 

 proposes to celebrate its jubilee by special meetings com- 

 mencing on July 4. The council also recommended that 

 the present time is favourable for applying for incorpora- 

 tion under a Royal charter, an opinion which was endorsed 

 b}- the members at the Thursday meeting. A presidential 

 address was delivered by Earl Cawdor, and premiums 

 were awarded to Dr. T. E. Stanton and Mr. H. C. Anstey 

 for papers, respectively, on the resistance of thin plates 

 and models in a current of water, and on the application 

 of internal-combustion engines for marine propulsion. 

 Thirteen papers in all were presented at the meetings, 

 abstracts from some of which we give below. 



A systematic series of experiments on wake and thrust 

 deduction has been carried out recently at the experi- 

 mental tank of Messrs. John Brown and Company's 

 establishment at Clydebank, and form the subject of a 

 paper contributed by Mr. W. J. Luke. Experiments were 

 made with twin and with single screws, and in all cases 

 where twin screws were run the experiments were made 

 in both directions of rotation. The work involved the 

 carrying out of at least 2000 experiments. The effective 

 horse-power may be expressed as the product of the thrust 

 horse-power and the hull efficiency, the latter quantity 

 being the product (i + w)(i— f), where w is the wake frac- 

 tion and t is the fraction of the total thrust by which the 

 tow-rope resistance is less than the thrust exerted by the 

 screw when propelling the ship. The experiments were 

 directed towards determining the variations in w and t 

 when (a) speed, (b) diameter, and (c) pitch ratio were 

 varied. With naked models a decrease in wake fraction is 

 evident with an increase of speed ; changes which appeared 

 for variations in diameter might be as much owing to 

 alterations in clearance ; variation in pitch had little or no 

 effect on either of the hull-eflRciency elements. 



Prof. B. Hopkinson, in his paper on the measurement 

 of shaft horse-power by torsion-meters, directed attention 

 to the need for further experimental work on full-sized 

 shafts with the view of ascertaining whether twist may be 

 produced by means of a longitudinal push or pull. Such 

 would imply, if no torque be applied, a peculiar structure 

 of the shaft, which might be described as a helical arrange- 

 ment of the fibres. Mr. C. E. Stromeyer gave results of 

 his observations of the brittleness of mild steel due to 

 nitrogen. It has not yet been possible to combine nitrogen 

 with steel by merely heating the two together, but this 

 may be effected by heating steel in an atmosphere of 

 ammonia. Ammonia may be present in blast furnaces if 



