July 25, 1907^ 



NATURE 



307 



(3) It must be capable of being promptly speeded to any 

 desired number of revolutions between dead slow and full 

 speed, and of being kept steadily at the required speed 

 for any length of time. " Dead slow " ought not to be 

 faster than one-quarter of full speed, and should be less 

 in very fast vessels. 



(4) it must be capable of running continuously for long 

 distances, with but short intervals between the runs, with- 

 out risk of stoppage or breakdown. 



(5) It must be capable of working well, not only in 

 smooth water, but also in heavy weather in a seaway, 

 where the varying immersion of the propeller causes 

 rapidly changing conditions of resistance. 



(6) All working parts must be readily accessible for 

 overhauling, and all wearing surfaces must be capable of 

 being promptly and easily adjusted. 



(7) The engine must be economical in fuel, especially at 

 its ordinary working speed. 



(8) It must be compact, light in weight, and well 

 balanced so as not to cause vibratiorv. 



(9) It must not involve any risk of accumulation 

 of gas in the ship such as could form an explosive 

 mixture. 



(10) It is a sine qua non that it must be capable of 

 using a fuel the supply of which at moderate price is 

 practically unlimited, and that could be obtained readily 

 in whatever part of the world a ship might happen 

 to be. 



Engineers and metallurgists may together succeed 

 in overcoming some day the difficulties of producing 

 large cylinders which will stand the high impulses 

 and great and rapid variations of temperature that occur 

 with internal combustion, but until that is accomplished 

 no great step ahead can be taken. There are no two 

 opinions, however, as to the advantages that would be 

 gained bv doing away with the present boilers and their 

 appurtenances, and abolishing with them much of that 

 verv arduous and disagreeable class of labour known as 

 marine stoking. 



The subject of oil fuel for marine boilers is interest- 

 ing, but I have no time to say more than that great 

 practical advance has been made with it during the 

 last decade, and a consumption as low as oo lb. 

 per I.H.P. per hour has been regularly realised in 

 mercantile vessels which employ the system of spraying 

 the liquid for combustion by means of hot air. .American 

 steamships have used oil fuel largely during the last three 

 years, under a combined system of high and low pressure 

 air respectively for desiccating or pulverising the oil 

 before combustion and for assisting the combustion after- 

 wards. This system has proved highly successful and 

 economical. Vessels of 14,0110 tons displacement belonging 

 to the Shell Transport Company have made voyages 

 regularly and successfully from Singapore to this country 

 by the long route of the Cape of Good Hope, and still 

 larger vessels have made equally successful voyages from 

 New York to San Francisco vid Cape Horn. 



The securing of all the comfort that is possible for 

 passengers on board ship is a modern idea. Formerly it 

 was thought sufficient to take them safely, and without 

 much, regard even to time, to their destination, and very 

 little attention was paid to comfort. Now it is the chief 

 object of the best shipping companies to leave and arrive 

 in port on fixed days, and even at fixed hours, and to 

 make the life of passengers on board ship as comfortable 

 and luxurious as on shore. 



Much of the comfort and luxury now in such demand 

 by passengers is provided by those who manage the ships, 

 and not by their designer. There is one very important 

 element of comfort, however, which the designer can do 

 much to supply, and to which increasing attention is 

 given. I refer to steadiness at sea, and freedom from 

 heavv rolling and pitching. But whatever mav be done 

 by the designer to give a metacentric height favourable to 

 steadiness, its proper regulation at sea by suitable stowage 

 of cargo and stores in the first instance, and by the 

 judicious use of water ballast afterwards, requires the 

 careful and close attention of the ship's officers if un- 

 pleasant rolling is to be kept at a minimum. .About 

 iS inches of metacentric height appears to give a satis- 



NO. 1969, VOL. 76] 



factory combination of resistance to inclination in large 

 ships with a long rolling period. 



After reducing the tendency to roll as much as possible 

 by suitable regulation of the metacentric height, the next 

 thing is to increase the resistance to whatever rolling there 

 may be. This is done chiefly by means of bilge keels, 

 which oppose the whole of their surface to the motion of 

 rolling, and are very effective in reducing its extent when 

 they are of sufficient depth. In ships I have known that 

 have been fitted after they were built with bilge keels 

 suitably formed and placed, the extreme angles of rolling 

 have been reduced to one-half. Their steadying effect is 

 now well known and admitted in the mercantile 

 marine. 



Other devices have been considered, and some have been 

 iried for still further increasing the resistance to rolling. 

 Sir Philip Watts described in the Transactions of the 

 Institution of Naval .-Xrchitects for 1883 and 1S83 the trials 

 in H.M. ships Ii'fliwiblc and Edinburgh of free water 

 in large chambers that extended right across the lower 

 deck, . the transverse motion of which, as the ship 

 rolled, was regulated by the shape of the water- 

 chamber and the depth of the water, so that it would 

 operate as a drag or brake upon the rolling motion. The 

 same device was tried in a small passenger ship, the 

 Ohio, in 1887, and in the City of New York and Ci(y of 

 Paris in i88g. In the two last-named ships the chamber 

 was upon the orlop deck. These water-chambers appear 

 to have given good results within certain limits of rolling 

 and when the motion of the water in them was well 

 timed, but the action upon the rolling depended very 

 much upon the way in which the water was regulated. 

 Whether it was on account of this or because of the space 

 occupied, or other objections that exist to the free motion 

 from side to side of large quantities of water in a ship, I 

 do not exactly know, but whatever the reason may be the 

 idea has been dropped. 



A proposal has recently been made by M. Victor' 

 Cremieu, of Paris, to check rolling bv means of a heavy 

 pendulum of long period that would oscillate in a closed 

 chamber filled with viscous fluid, and he has contributed 

 a paper upon the subject to the Academic des Sciences. 

 His idea is to make the length of pendulum and its weight 

 such as would give it an angular moment up to possibly 

 one-tenth that of the ship. The clearances between the 

 pendulum and the sides of the chamber, and the degree 

 of viscosity of the liquid — M. Cremieu suggests oil, or a 

 mixture of water and glycerin — would be so arranged as 

 to make the energy of the pendulum most effective in 

 offering resistance to rolling. .\ simplification of the 

 apparatus is suggested by substituting for the pendulum 

 a weight that would move backwards and forwards upon 

 a curved path in a transverse chamber or tube filled with 

 the viscous liquid. In both cases the principle is that of 

 opposing the rolling of the ship bv the statical moment 

 of the oscillating weight, and reducing the energy of motion 

 by generating heat in the fluid through which the weight 

 moves. 



Sir John Thornycroft described an automatic steadying 

 anparatus in i8q2, which was fitted in his steam-yacht 

 Cecile with some success. It consisted of a most ingenious 

 controlling gear which regulated the motion from side 

 to side of a heavy weight in opposition to the rolling 

 motion. It was very cleverly worked out, and destroyed 

 much of the rolling in a vessel of great metacentric height 

 and very short period. This idea also has not been 

 followed up. 



A device which appears promising for increasing the 

 resistance to rolling is one that has been ingeniously and 

 effectively worked out by Dr. Otto Schlick, of Hamburg, 

 a verv eminent marine engineer. It depends upon gyro- 

 scopic action, and its principle was fully described by Dr. 

 Schlick at the Institution of Naval .Architects in 1004. 

 This principle appears to deserve serious consideration, 

 and Is already ripe for application to the smaller classes 

 of steamers. I am informed that an apparatus is being 

 manufactured for placing In the Hamburg-.Amerlcan Com- 

 pany's passenger-boat Silvana, of about 1000 tons, which 

 runs between the Elbe and Heligoland, and that Dr. Schlick 

 is designing a standard gyroscope that will be suitable for 



