March 30, 1893] 



NATURE 



521 



by means of photographing the waves' profile. The author also 

 towed a flat plank, 28 feet long, at a speed of 406 feet a minute. 

 The speed of current recorded at distances of i foot, 7 feet, 14 

 feet, 21 feet,and 28 feet from the leading end were respectively 16 

 per cent. , 37 per cent. , 45 per cent. , 48 per cent. , and 50 per cent, 

 of the velocity of the plank. These proportions appear to be 

 maintained at all speeds between 200 and 400 feet per minute. 

 Having thus determined the maximum velocity of the frictional 

 water, other experiments were made with this plank to show 

 the manner in which the motion of the water in contact with 

 the surface was gradually imparted to the layers of water lying 

 underneath. This was done by means of tubes, the forward 

 ends of the tubes being open, and their after ends connected to 

 gauge glasses. The results of experiments at 200, 300, and 

 400 feet per minute would appear to show that the velocity 

 decreases in a geometrical progression as the distance from the 

 surface increases in arithmetical progressions. The retardation 

 of velocity in the somewhat analogous conditions of orbital 

 wave motion of the flow of rivers, and possibly of glaciers, 

 appears to confirm the foregoing observations as regards the 

 ratio of decrease in velocity of the frictional weight. Mr. 

 Calvert next went on to refer to the labours of Dr. Froude, and 

 his report to the British Association for 1874. We regret that 

 space does not allow us to accompany him in this most 

 interesting investigation, and we must refer our readers to the 

 Transactions, in which the whole matter will be published in 

 full. In the discussion which followed. Dr. White, Mr. Froude, 

 and others spoke, but no new facts were brought forward. 



The next paper of interest was a contribution by Mr. A. J. 

 Durston, Engineer-in-Chief of the Royal Navy, and dealt 

 with the important matters which are comprised in the 

 problem of leaky tubes. Our readers will be aware of the 

 trouble that has arisen in the Navy from the leakage at tube- 

 plafes and tube ends, where marine boilers have been driven to 

 their maximum. The difficulty has been got over to a certain 

 extent by the introduction of a peculiar form of ferrule. These 

 ferrules are bent over at their ends and protect the joint of the 

 tube and tube-plate from the fierce impact of flame. 

 Naturally the ferrules themselves get burnt away, as there is an 

 air space between them and the heated surface of the boiler by 

 which the heat would be abstracted from the end. With malle- 

 able cast-iron, the destruction is not so rapid as one would 

 imagine, for, we believe, although the fact was not staled at the 

 meeting — that a spare set is all that is provided for a commis- 

 sion, that is to say, two sets of ferrules, one in position and one 

 spare will last for three years. The experiments upon which 

 Mr. Durston's paper is founded were made in various ways, 

 with parts of boilers constructed especially for the 

 purpose. The temperatures were generally ascertained by 

 means of plugs at fusible alloys let into the plates through which 

 the heat was transmitted. An mteresting series of experiments 

 was also made as to the temperature of the products of combus- 

 tion at different distances within the tubes of a boiler. This 

 was done by means of a Le Chatelier pyrometer. And it may 

 be said that the curve of temperatures obtained in this way 

 agrees very closely with the curve of evaporation obtained by Mr. 

 Wye Williams. We have not space to give the details of Mr. 

 Durston's many trials. One very striking thing was the ex- 

 tremely deleterious result of grease in the boiler, by preventing 

 the proper transmission of heat. 



Mr. Milton's paper followed. Its object was to show that 

 when a cylindrical boiler of the return tube type is subjected to 

 pressure the staying of the combustion chambers to the shell 

 has an effect of distorting the shell, dragging it out of the 

 cylindrical form, thus the flat surfaces of the combustion cham- 

 bers tend to bulge inwards on themselves, and away from 

 the shell. This sets up strains which are not equally distributed 

 around the whole circumference of the shell. In order to over- 

 come this, Mr. Milton proposes to stay the combustion cham- 

 bers with stays radiating from the centre of the shell and dis- 

 tributed all round, so that the stress will be equal on all parts. 

 The author quoted experiments showing that the distortion due 

 to the cause named is far greater than is generally supposed by 

 engineers, in one case amounting to as much as one-eighth of 

 an inch on the diameter. This was at a pressure of 320 lbs. on 

 a boiler 14 feet in diameter having three combustion chambers. 



Herr Schlick's paper was of remarkable interest. He has 

 devised an instrument by which a record is obtained, not only 

 of the vertical but of the horizontal vibrations of steamers. 

 Without the aid of illustration it would be impossible for us to 



NO. 1222, VOL. 47] 



describe this very ingenious apparatus. Vibration is an import- 

 ant factor in the design of modern steamers of high speed. 

 Our readers will remember Mr. Yarrow's contributions on this 

 subject, and the very valuable practical results he adduced from 

 the experiments made on torpedo boats. In ocean steamers the 

 question of vibration is now one of great moment. In one well- 

 known Atlantic liner the vibration at one time was a seriou.s^ 

 objection to the vessel, and the nodal points of vibration were 

 well marked in the length of the vessel, so much so that cabin.s 

 on these points were greatly preferred, and those who were 

 fortunate enough to be in the confidence of the stewards were 

 able to secure these cabins. It has been shown that the action of 

 the screw itself had very little to do with this vibratory dis- 

 arrangement, it being the synchronisation of the reciprocating 

 parts of the engine with the natural vibration of the structure 

 of the hull that produces the effect iti the most aggravated 

 form. 



Mr. Hok's paper on curves of stability is a valuable con- 

 tribution to the Transactions of the Institution. The author is 

 hinnself engaged practically in work of the nature which he de- 

 scribes, being a draughtsman in a shipyard on the north-east 

 coast. The Institution can hardly have too many papers fron> 

 authors of Mr. Hok"s position and attainments. We do not 

 propose here to enter into a description of the geometrical 

 principles upon which the author bases his formula, and must 

 refer our readers to the Transactions of the Institution for details. 

 The system claims to give no more than approximation, but it 

 is applicable to all kinds of ships and has the great merit of being 

 readily constructed. 



The last evening of the meeting Mr. John Inglis gave some 

 interesting particulars of experiments made with a view to 

 test the desirability of running triple compound engines as two 

 cylinder compounds when low power only is required. The 

 system has been frequently advocated with a view to save coal, 

 but Mr. Inglis's results do not seem to bear out this claim. Two 

 four-hours' trials were made, one with the engine working as an 

 ordinary triple, and the other with the intermediate cylinder 

 thrown out of use. Working triple, the I.H.P. was 810 ; 

 working two cylinders, 351. In the former case the coal con- 

 sumed per I.H.P. per hour was 147 pounds. With the inter- 

 mediate cylinder out of use the coal was 2-238. The consump- 

 tion of feed water corresponding was I5"25 pounds, and 23 "iS 

 pounds per I.H.P. per hour. Of course the comparison must 

 not be taken as indicating degree of the superiority of the 

 triple expansion engines over the ordinary compound, great 

 as that superiority undoubtedly is. 



A paper by Mr, Cole on the same subject follows, but the 

 results obtained are not sufficiently conclusive to demand 

 quotation. 



The last paper at the meeting was the contribution by Mr. 

 Edwards. Its title sufficiently explains its scope, and it would 

 be quite impossible for us to follow the author's explanation 

 without the aid of the diagrams which he exhibited on the walls 

 of the theatre. 



The chief event of the meeting was reserved for the last. It 

 was the presentation of an address to Lord Ravensworth, who 

 for fourteen years has occupied the position of president to the 

 Institution. He now retires, his successor being Lord Brassey. 

 The address referred to the great services that Lord Ravens- 

 worth had rendered to the Institution, and the authors of 

 it gave utterance to no conventional platitudes. Lord 

 Ravensworth has worked hard for the Institution of Naval 

 Architects, and has conducted its meetings without favour to 

 any, so that the humblest member could get a hearing equally 

 with the most distinguiihed. It is not always so in societies of 

 this nature. 



A summer meeting of the Institution will be held at Cardift, 

 a very cordial invitation having been received from the Welsh 

 metropolis. The meeting promises to be of unusual success, 

 judging by the programme which is set forth, and the arrange- 

 ments made. 



THE ACTION OF GLACIERS ON THE LAND 

 pKOF. T. G. BONNEY, F.K.S., read a paper to the 

 last meeting of the Royal Geographical Society on the 

 question, Do glaciers excavate ? In view of the correspondence 

 recently published in our columns the arguments adduced in sup- 

 port of the negative conclusions may be cited in some detail. 



