520 



NATURE 



[April 2, 1896 



During April the comet passes from near 58 Persei to a little 

 south of 7j Aurigse. In the latitude of London it is circumpola/ 

 throughout the month. 



Search Ephemeris for Comet 1889 V.— The following 

 search ephemeris for the expected return of Comet 1889 V 

 (Brooks) is given by Dr. Bauschinger {Ast. Nach., 3334) : — 

 R.A. Decl. Bright- 



The ephemeris is for Berlin midnight, and the unit of theo" 

 retical brightness is that on 1889 July 8, the date of the first 

 accurate observation. When last seen in January 1891 by Prof. 

 Barnard at the Lick Observatory, the calculated brightness was 

 o"o8, so that the comet should even now be brighter than when 

 it was last observed ; it is, however, not very favourably 

 situated for European observers. During April the motion of 

 the comet is a little north of the line from ij/ to f Capricornii. 



INSTITUTION OF NA VAL ARCHITECTS. 

 ''PHE annual spring meeting of the Institution of Naval 

 ■*- Architects was held last week, commencing Wednesday, 

 the 25th ult., and being carried over Thursday and Friday, the 

 two following days. The new President, the Earl of Hopetoun, 

 who has succeeded Lord Brassey, occupied the chair throughout 

 the meeting. 



There was a long list of papers to be read, the following being 

 on the agenda : — 



(i) "Watertight Doors, and their Danger to modern fighting 

 Ships," by Captain the Right Hon. Lord Charles Beresford, 

 C.B., R.N. 



(2) " Watertight Doors," by Colonel Nabor Soliani, Director 

 of Naval Construction, Royal Italian Navy. 



(3) " Some Geometry in Connection with the Stability of 

 Ships," by J. G. Bruhn. 



(4) "The Causes of Mysterious Fractures in the Steel used by 

 Marine Engineers as revealed by the Microscope," by A. E. 

 Seaton. 



(5) "The Measurement of Feed and Circulating Water, &c., 

 by Chemical Means," by C. E. Stromeyer. 



(6) " Salvage Appliances," by J. G. Kinghorn. 



(7) " Compound Marine Boilers," by Colonel Nabor Soliani, 

 Director of Naval Construction, Royal Italian Navy. 



(8) " Water-tube Boilers," by J. Watt. 



(9) "Circulation in Water-tube Boilers," by Prof. W. H. 

 Watkinson. 



(10) "The Non-uniform Rolling of Ships," by R. E. Froude, 

 F.R.S. 



(11) "A New Theory of the Pitching Motion of Ships on 

 Waves, and of the Stresses produced by this Motion," by 

 Captain A. Kriloff, Professor at the Naval Academy of St. 

 Petersburg. 



(12) "Notes on the Carriage of Grain Cargoes," by George 

 Herbert Little. 



The paper by Lord Charles Beresford set forth the views of a 

 naval officer on the question of watertight doors. It may be 

 said generally that the piercing of bulkheads has been done 

 at the request, or perhaps more correctly speaking, the insistence 

 of naval officers, who have found it difficult to work their ships 

 with partitions in them not allowing means of ingress and 

 egress from one compartment to the other. Lord Charles 

 Beresford, however, differs from the majority of naval captains, 

 and considers that bulkheads are too much pierced. He would 

 do away with a large number of openings in a ship. He tells us 

 that in the Magnificent and Majestic, which are the most power- 

 ful battleships in the service, and, therefore, in the world, there 

 are 150 compartments in each ship, and 208 doors. Many of 

 these of course are not in positions which are of vital import- 

 ance, so far as flooding of the ship would be concerned in case of 

 accident. He proposes to do away with nineteen of these doors 



NO. 1379, VOL. 53] 



in the most important part of the ship, and twenty-three would" 

 be made smaller, or modified so as to give additional safety ia 

 accordance with his proposals. This would undoubtedly add to 

 the safety of the ship, and equally without doubt it would 

 detract from the convenience of those inhabiting it. The latter 

 may seem at first a small matter, but, as was pointed out during 

 the discussion which followed the reading of the paper, conveni- 

 ence is to a large extent a measure of efficiency in action. In 

 fighting a ship it is necessary for the men to move from part to 

 part with great rapidity. This naturally means openings in bulk- 

 heads ; for if a man, say the chief engineer, in order to get 

 from one part of the vessel to another, has to climb up on deck J 

 to surmount a bulkhead, and descend on the other side, time will 9 

 be occupied in the transition. In the rapid handling of ammuni- * 

 tion, also, it is absolutely necessary that direct access should be ob- 

 tained to various compartments ; whilst for bringing coal from the 

 bunkers to the stokehole floors, divisions must have openings 

 made in them. It is also necessary to consider the question of 

 habitability. A ship requires ventilation, otherwise it is im- 

 possible to live in her ; at present a good deal of space is given 

 to steam fans and air conduits, for this purpose. If bulkheads 

 are to be unpierced, the difficulty of ventilation becomes more 

 pronounced. It will be seen, therefore, that the question of 

 openings in bulkheads, whether fitted with water-tight doors or 

 not, is not of so simple a character as might at first appear. In 

 fact in this element of warship design, as in all others, "com- 

 promise " must be the watchword. It is necessary not only for 

 naval officers but for naval architects as well to meet and dis- 

 cuss this matter. Up to the present it has been rather that the 

 naval officer has demanded watertight doors, and the ship- 

 designer, or naval architect, has opposed the demand. It is- 

 evident, from the discussion which followed the reading of Lord 

 Charles Beresford's and Colonel Soliani's papers, that opinions- 

 are divided. It is essential that the matter should be threshed 

 out, and the best compromise, according to our lights, should be 

 adopted. 



Colonel Soliani's paper dealt with different forms of water- 

 tight door. It was very fully illustrated, and will be a valuable 

 source of reference to shipbuilders and naval architects. 



In Mr. Bruhn's paper the question of stability of ships was 

 treated, both in an historical and a mathematical manner. 

 This contribution was read in brief abstract, and there was. 

 practically no discussion upon it. It is not one that would bear 

 condensation very readily, and in any case could not be under- 

 stood without the use of the diagrams which accompanied it. 

 It dealt with the problem of constructing geometrically a set of 

 cross curves of stability for inclinations from 90° to 180°, the 

 corresponding curves from zero to 90° being known. Another 

 section dealt with the determination of the direction in which, 

 the centre of buoyancy moves when a ship is inclined in a givea 

 direction. Lines of curvature and geodetic lines as curves of 

 buoyancy, relations between the surfaces of buoyancy and 

 flotation, and an extension of Leclert's theorem were subjects 

 also dealt with ; whilst the paper concluded with a geometrical 

 construction for finding the length n, or the radius of curvature 

 of the curve of flotation, from the usual information given on 

 metacentric diagrams. 



Mr. Seaton's paper was an extremely interesting one, and will 

 prove of great practical value to engineers. As is well-known, 

 the author is the managing director of Earle's Shipbuilding and 

 Engineering Works at Hull. Some time ago part of the shaft- 

 ing of a screw steamer with which he had to do suddenly gave 

 way. This shaft was made of steel containing from 0*2 per cent, 

 to 0*25 per cent, of carbon, and its ultimate tensile strength was 

 guaranteed to be not more than 30 tons, with an elongation of 

 25 per cent, in 5 inches. Mr. Seaton determined to make an 

 inquiry into the composition of this shaft, and for that purpose 

 it was subjected to chemical analysis. We need not repeat this- 

 analysis ; it will be sufficient to state that it showed a very high 

 proportion of undesirable elements in the steel. The most in- 

 teresting part of the investigation was that carried out by 

 Prof. J. O. Arnold, of Sheffield, who prepared micro-sections in, 

 the usual way. The chief point of the paper consists in the 

 fact that chemical analysis is shown to be insufficient to give the 

 engineer information as to the value of a given steel used for 

 structural purposes. For instance, sulphur which is objectionable 

 under certain conditions may be present to a considerable extent 

 in a steel casting or forging, but though it may be of no serious 

 moment if in one form, will be conducive to most disastrous re- 

 sults in another form. The chemist, as Mr. Seaton pointed out» 



