20S 



NATURE 



[Junk 2;, 1895 



ment is given in detail in the paper, and is made clear by means 

 of diagrams. 



M. Daymard's pajier was of a commercial rather than a 

 scientific interest. We all recognise that our tonnage laws are 

 anomalous. Unfortunately they have become so interwoven 

 with our commercial system, that it would require nothing 

 ess than a revolution to reduce them to a common-sense 

 standard. M. Oaymard commands our admiration by his 

 courageous attempt, but .is was shown during the discussion, 

 the new laws he proposes, however unexceptionable from a 

 scientific stand(X)int, would introduce undesirable features. .-Vs 

 indicated by the title, he proposes to take the whole external 

 volume of a ship in e.slimating her tonnage and load-line as 

 well as stability. This seems reasonable, but as an illustration 

 of the undcsirability of such a law . it may be pointed out that 

 the tendency of the ship designer working for commercial ends, 

 as all designers of mercantile vessels must do, would be to 

 stint engine accommoiiation to the manifest danger and dis- 

 comfort of the engineering staff. The subject, is, however, 

 one which we need not pursue. 



Mr. Martell's contribution was one full of information and 

 nstruction to the designer of light draught vessels. Its value ; 

 consisted chiefly in the thirteen plates of illustration containing 

 details of construction of a large number of vessels designed 

 for shallow water navigation. The descriptions which accom- 

 panied the illustrations were also of great practical information. [ 



M. Sigaudy"s pa|)er, on coupling boilers of different systems, 

 was a brief but instructive contribution. The introduction of j 

 the watcr-lulie Iwiler, which may be said now to lie complete in 1 

 the case of small and exceedingly fast war vessels, appears likely 

 to make headway even in craft not of this special description. 

 The water-lube Ixjiler is. however, something new, and the 

 average engineer, engaged in practical work, always shies at 

 novelties. That is but natural, and it is the result of common 

 sense that caution should l)c observed when risks have to be 

 run. By the system a<lvocated by M. Sigaudy, the risk is re- 

 duced to the smallest dimensions. In a tug-boat built by his 

 Company, an ordinary return tul)e marine Iwiler is combined w ith 

 wo water-tulx; lioilers. The engineers of the vessel have there- 

 fore a steam generator at their dis|x>sal, which they thoroughly 

 understanil, and which is sufficient to supply steam to drive the 

 lifiat at miKlerate speed. .Should the water-tube lioilers fail, 

 therefore, they would not \k left helpless. One advantage of the 

 watcr-tul)e Ixiilers is that steam can l>e raised very quickly, and 

 this is a ver)' desirable feature in a tug which has at times to be 

 used in cases of emergency. The time occupied uix>n two trials 

 n raising sleani w.is resi>ectivcly 22 and 23 minutes. The con- 

 sumpiiiin of fuel was i 78 lbs. |x;r horsc-|x)wer per hour, which, 

 it need hardly be said, is a very satisfactory result. No trouble 

 has Ix-en found, since the tug has Ix-en used, to arise from the 

 combination of the two systems of boilers. In the discussion 

 which followed the reading of this paper, Mr. Yarrow stated that 

 a similar system has been adopted by the Dutch (".overnment in 

 .some cruisers they are having huill. These vessels are n.^turally 

 of much larger size than the tug-boat described by M. .Sigaudy, 

 and their trials will Ik.- looked forward to with considerable in- 

 terest by the naval wurld. 



I>r. Elgar's jxiper, on the cost of war-ships, constituted a new 



dc|»rture in the annals .>f the Institution. It has generally been 



considered, if not expressly slated, thai financial questions are 



lalKioed by the Inslilution. In the case of ("lovernment vessels, 



<loublless more lalilude should be .illnwed. but in any event it is a 



ditficull thing 10 exclude money considerations from discussions 



■r iitijtcls which have a commercial liasis. .\fler all, ships 



ill lo earn money, and even the designer of war-ships has 



!■ Ihe i|ueslion of cost incessantly before him. It woulil be 



-. for instance, .suggesting a new fr>mi of marine engine, 



■ .r i»rfecl from a scientific point of view or economifal in 



. if its first cost were lo Ik; prohibitive. In the dis- 



h followed Ihe reading of the pajier. views similar 



; ressed by prominent niemliers of the Institution, 



thai more lalilude will l>e given for the future 



for our own («rl, il will l>e im|x>ssiblc to 



ir.-iiai I, III uiiytliing like reasonable s|>acc, the vast quaiitilies of 



l,M,.,.-« given bv Ih'- author of ihe |>a|)er. His analysis of ihc 



;.li-. and il may Ik- staled, briefly, led lo 



H (jorkyardbuilt war vessels are cosling 



;,„ ,,,.,, , i .Id, relatively lo the work put into them. 



Il may Ik- staled, although Dr. Elgar failed lo |>oinl the fact oul 

 in hi.« |xil>er, that this happy stale of affairs is largely due lo Ihe 

 good work he himself did when Director of Dockyards. 



NO. i,v^9. VOL. 52] 



The last two papers of the meeting were on the subject of the 

 hour, water-tube boilers. M. Normand, the well-known builder 

 of torpedo boats at Havre, and one of the most scienlific and 

 best informed marine engineers of the day, gave a very valuable 

 analysis of the points which should be observed in designing a 

 water-tube boiler. Naturally, circulation occupied his chief 

 attention, and it may be said briefly that if sufticient activity of 

 circulation of water and steam in the boiler can be maintained, 

 that boiler is likely lo lie an cthcienl steam generator. How lo 

 obtain such circulation is a complex and disputed question, anil 

 here we find our own great authority on the subject, Mr. 

 Thornycrofi, at issue with the author of the paper. Mr. Thorny- 

 croft, as is well known, is a strong advocate of above water dis- 

 charge into Ihe steam drum. M. Normand, on the other hand, 

 upholds "drowned " tubes. The subject is a large one, fiir too large 

 for discussion in a report of Ibis nature. To us it appears that 

 M. Normand is not warranted in all the assumptions upon which 

 he ba.ses his conclusion, and further il may be said that Mr. 

 Thornycrofi has exiierimental data on his side in maintaining 

 that the circulation of water is more active with above water 

 discharge than w ith drowned tubes. Whether with the latter the 

 circulation is suHiciently active for all practical purposes is of 

 course another mailer, the bearing of which it remains for 

 practical experience lo prove. l-"or, like the problem >!. 

 Berlin attacked in his paper, it is not solvable by theoretical 

 analysis. 



-Mr. Mark Robinson, in his paper, described a very promising 

 form of water-tube boiler which has been introduced in France 

 by M. Niclausse, the inventor. Without illustrations it would 

 be utterly imjOTssible lo make the design clear ; but il may be 

 said that the principle followed is that of the KieUi tube, in 

 which circulation is promoted by means of a pipe inside and 

 coaxial with the heating lube, furiously enough, however, 

 the lubes in the Niclausse boiler are horizontal, or approxi- 

 mately horizontal, so that the circulation is maintained in the 

 "header" which is divided by a diaphragm, the difference be- 

 tween the specific gravities of the water, or water and steam, 

 contained on each side of the diajihragm causing Ihe movement 

 of the water. This boiler appears to be one of great promise 

 amongst water-lube boilers in situations where ihe highesi 

 evai)oralive efficiency is not required. Il is, however, in these 

 positions thai the ordinary return lube boiler is strongest. 

 j Whether il will be supplanted by a water tube boiler remains 

 I to be seen ; but should such be the case, Ihe Niclausse Iwiler 

 has the anpearance of being a formidable competitor. 



No account of Ihe Paris meeting w<iuld be complete without 

 reference being made to the beautiful series of jihotographs 

 shown by .M. Berlin in illustration of Ihe movements of .ships in 

 a sea-wave. These photographs were taken by the method 

 devised by M. .Marey, to which reference has already been 

 made in these columns. \ dozen or more different views are 

 given of a ship during its ])a.ssage through a wave, and ihe 

 whole movement can thus be fixed and analysed. The value of 

 such <lata to ihe naval architect is, of course, immense. In 

 connection with these photographs, which were shown on the 

 .screen, there were also exhibited some very beautiful projecli.ms 

 of photographs in colours. These were shown by M. Charles 

 Comte, one of M. Marey's iissislunl.s. The subject is one which 

 has been attracting attention of late, and has been referred to 

 elsewhere in these columns. 



METEOROLOGICAI. PROIiLEMS FOR 

 PHYSICAL I.AIiORA TORIES. 



IN response lo several refpiesls from both teachers and slii(lent.s 

 for suggestions as to problems that can be taken up in 

 iihysical lalniralories, I'rof. Cleveland Abbe gives Ihe following 

 list of subjects, in the American Meteorological loiirnal for May. 

 The initialled subjects are due to I'rof. C. I'". Marvin. 



Subjects for Kxi'ERIMk.siai. Investigation. 



(1) The inlernal sensitiveness of ihermomelers, or the lenglh 

 of time required lo bring the top of the thermometer column lo 

 Ihc |)roper reading when the external surface of bulb and stem is 

 kept at a constant temperature below, or above, some initial 

 Icmperalure. 



(2) The influence of the wind on the pressure within a room, 

 or other closeil space, containing a bar<iineler. 



(3) The influence of the condition of any surface (as to 



