August 24, 1882] 



NA TORE 



397 



extent counterbalanced by the value of the steamship, which 

 bears to that of the sailing vessel per net carrying ton the pro- 

 portion of 3 : I, thus reducing the ratio in favour of steam ship- 

 ping as 1329 to 103S, or in round numbers as 4 : 3. In 

 testing this result by the charges of premium for insurance, the 

 variable circumstances of distance, nature of cargo, season and 

 v 'yage have to be taken into account ; but judging from in- 

 formation received from shipowners and underwriters of 

 undoubted authority, I find that the relative insurance paid for 

 the two classes of vessel represents an average of 30 per cent, in 

 favour of steam shipping, agreeing very closely w ith the above 

 deductions derived from statistical information. 



In considering the question how the advantages thus established 

 in favour of steam-shipping could be further improved, attention 

 should be called in the first place to the material employed in 

 their construction. A ne«' material was introduced for this pur- 

 pose by the Admiralty in 1876 — 78, when they constructed at 

 Pembroke dockyard the two steam corvettes, tlie Iris and Mer- 

 riirr, of mild steel. The peculiar qualities of this material are 

 such as to have enabled shipbuilders to save 20 per cent, in the 

 weight of the ship's hull, and to increase to that extent its carrying 

 capacity. It combines with a strength 30 per cent, superior to 

 that of iron such extreme toughness, that in the case of collision 

 the side of the vessel has been found to yield or bulge several 

 feet without .showing any sign of rupture, a quality affecting the 

 question of sea risk very favourably. When to the use of this 

 material there are added the advantages derived from a double 

 bottom, and from the division of the ship's hold by means of 

 bulkheads of solid construction, it is difficult to conceive how 

 such a ve-sel could peii-h by collision either with another vessel 

 or with a sunken rock. The spaces between the two bottoms 

 are not lo^t, because they form convenient chambers for water 

 ballast, but powerful pumps should in all cases bej added to 

 meet emergencies. 



The following statement of the number and tonnage of vessels 

 building and preparing to be built in the United Kingdom on the 

 30th of June last, which has keen kindly furnished me by 

 Lloyd's, is of interest as showing that wooden ships are fast 

 I ecoming obsolete, and that even iron is beginning to yield its 

 t lace, both as regards steamers and sailing ships, to the new 

 material mild steel ; it also shows that by far the greater number 

 of vessels now building are ships of large dimensions propelled 

 by engine pow er : — 



Mi i.D Steel. Iron. Wood. Total. 



Tons Tons Tons Tons 



No. gross. No. gross. No. gross. No. gross. 



Steam So 159.751 ••• 555 929,921 — 6 460 ... 650 1,090.132 



Sailing 11 16.800 ... 70 120,259 •■■ 49 4,635 — x 3° 141.694 



100 176.551 ... 625 1,050,180 ... 55 5,095 ... 780 1,231,826 

 If to the improvements already achieved could be added an 

 engine of half the weight of the present steam engine and 

 boilers, and working with only half the present expenditure of 

 fuel, a further addition of 30 per cent, could be made to the 

 cargo of an Atlantic propeller vessel— no longer to be called a 

 steamer — and the balance of advantages in favour of such 

 vessels would be sufficient to restrict the use of sailing craft 

 chiefly to the regattas of this and neighbouring ports. 



The admirable work on the " British Navy," lately published 

 by Sir Thomas Bra-sey, the Civil Chief Lord of the Admiralty, 

 Snows that the naval departm: t of this country is fully alive to 

 all improvements having regard to the safety as well as to the 

 fighti g qualities of Her Majesty's ships of war, and recent 

 experience goes far to prove that although high speed and 

 manoeuvring qualities are of the utmost value, the armour plate 

 which appeared to be fast sinking in public favour is not without 

 its value in actual warfare. 



The progressive view s perceptible in the construction of the 

 navy are further evidenced in a remarkable degree in the hydro.- 

 graphic department. Captain Sir Frederick Evans, the hydro- 

 grapher, and Vice-President of the British Association, gave 

 us at York last year a very interesting account of the progress 

 made in that department, which, while dealing chiefly with the 

 preparation of charts showing the depth of water, the direction 

 and force of currents, and the rise of tides near our shores, con- 

 tains also valuable statistical information regarding the more 

 general questions of the physical conditions of the sea, its 

 temperature at various depths, its flora and fauna, as also the 

 rainfall and the nature and force of prevailing winds. In con- 

 nection with this subject the American Naval Department has 

 taken an important part, under the guidance of Captain Maury 



and the Agassiz father and son, whilst in this country the per- 

 sistent labours of Dr. William Carpenter deserve the highest 

 consideration. 



Our knowledge of tidal action has received a most powerful 

 impulse through the invention of a self-recording gauge and 

 tide-predicter, which will form the subject of one of the discourses 

 to be delivered at our present meeting by its principal originator, 

 Sir William Thomson ; when I hope he will furnish us with an 

 explanation of some extraordinary irregularities in tidal records, 

 observed some years ago by Sir [>>hn Coode at Portland, and 

 due apparently to atmospheric influence. 



The application of iron and steel in naval construction rendered 

 the u-e of the compass for sme time illusory, but in 1839 Sir 

 George Airy sh iwed h iw the errors of the compass due to the 

 influence experienced fn m the iron of the ship, may be perfectly 

 corrected by magnets and soft iron placed in the neighbourhood 

 of the binnacle, but the gnat size < f the needles 111 the ordinary 

 compasses rendered the correction of the qualrantal errors 

 practically unattainable. In 1876 >ir William Thorns in invented 

 a cdmpass with much small- r needles than those previously used, 

 which allows Sir Ceorge Airy's principles to be applied com- 

 pletely. Wiih this compass correctors can b"; arranged so that 

 the needle shall point accurately in all directions, and these 

 correctors can be adju ted at sea from time to time, so as to 

 elimina e any error which may arise through change in the 

 ship's ma.netism or in the magnetism induced by the earth 

 through change of the ship's po.-ition. By giving the compass 

 card a 1 mg period of free dilation great steadiness is obtained 

 when the ship is rolling. 



Sir William Thorn on has also enriched the art of navigation 

 by the invention of two s unding machines ; the one being 

 devised for ascertaining great depths veiy accurately ii less than 

 one-quarter the time formerly necessary, and the other for taking 

 depths up to 1 to fathoms without stopping the ship in its 

 Onward course. In both these instruments steel pianoforte wire 

 is used instead of the hempen and silken 1 nes fori] erly employed ; 

 in the latter machine the record of depth is obtained not by the 

 quantity of wire run over its counter and brake wheel, but 

 through the indications produced upon a simple pressure gauge 

 consisting of an inverted via s tube, whose internal surface i 

 covered beforehand wilh a preparation of eliminate of silver 

 rendered colourless by the sea-water up to the height to which 

 it penetrates. The value of this instrument for guiding the 

 navigator within what he calls "soundings" can hardly be 

 exaggerated ; with the s unding machine and a good chart he 

 can'generally make out his p sition correctly by a succession of 

 three or four casts in a given direction at given intervals, and 

 thus in foggy weather is made independent of astronomical 

 observation- and of the sight of lighthouses or the shore. By 

 the proper use of this apparatus, such accidents as happened to 

 the mail steamer Moscl not a fortnight ago would not be possible. 

 As regards the value of the deep-sea instrument I can speak 

 from personal experience, as on one occasion it enabled those in 

 charge of the Cable s.s. Faraday to find the end of an Atlantic 

 Cable, which had parted ill a gale of wind, with no other 

 indication of the locality than a single sounding, giving a depth 

 of 950 fathoms. To recover the cable a number of soundings 

 in the supposed neighbour!) tod of the broken end were taken, 

 the 950 fathom contour line was then traced u] on a chart, and 

 the vessel thereupon trailed its grapnel two miles to the eastward 

 of this line, when it soon engiged the cable 20 miles away from 

 the point, where dead reckoning had placed the ruptured end. 



Whether or not it will ever be practicable to determine 

 oceanic depths without a sounding line, by means of an instru- 

 ment based upon gravimetric differences, remains to be seen. 

 Hitherto the indications obtained by such an instrument have 

 been encouraging, but its delicacy hts been such as to unfit it for 

 ordinary use en board a ship when rolling. 



The time allowed me for addressing you on this occasion is 

 wholly insufficient to do justice to the great engineering works 

 of the present day, and 1 must therefore limit myself to making 

 a short allusion to a few only of the more remarkable enterprises. 



The great success, both technically and commercially, of the 

 Suez Canal, has stimulated M. de Lesseps to undertake a similar 

 work of even more gigantic proportions, namely, the piercing of 

 the Isthmus of Panama by a ship canal, 40 miles long, 50 yards 

 w ide on the surface, and 20 yards at the bottom, upon a dead 

 level from sea to sea. The estimated cost of this work is 

 20,000,000/., and more than this sum having been subscribed, 

 it appears unlikely that political or climatic difficulties will stop 



