204 EXPERIMENTAL CRUISE OF THE 



Aa I liave already described the engines elsewhere, I shall only revert to them 

 here for the purpose of confirmiog the axiona of steam navigation, that the most 

 powerful engine is also that which while giving the highest speed yet practically 

 costs the least. The Napoleon had proved this in the Crimean war, where she 

 alone did more service than many vessels together; and the present experiments 

 have made this truth still clearer if possible. Tha Napolton, with tonnage 5200 

 and engine of 900 horse power, that is, one horse power to 5-8 tons, was beaten 

 in the trials of speed by the Magenta and Solferino, whose engines of lOOOborsea 

 give *l toes to the single power. In all the trials, with 2, 4, 6, or 8 furnaces, these 

 two vessels invariably headed the list, and in comparing the others with them, 

 not at their highest (for the others could not have kept up then) but at a mode- 

 rate speed, the consumption of coal was remarkably iu their favor ; thus there was 

 more effect produced and less expenditure. Relatively to the Ihurville, of 650 

 horse power and 4550 tons, the difference is surprising. It turned out that, during 

 the whole cruise, the Tourmlle was obliged to have a greater number of furnaces 

 in blast than the rest of the squadron, so much so that when the rest, at the com- 

 pletion of the esperimeni had still enough coal in store to return to Cherbourg 

 with four furnaces going, the Tourville liad exhausted her stock, and was obliged 

 to make for Lisbon to take in more. This advantage even in ordinary navigation 

 cannot be too highly estimated, and still more so in a real campaign, for the sphere 

 of action of a steamer is one ofthe most important elements of its power. The SolfC' 

 rino with two furnaces going, and a rate of 10 knots, consumes 225 tons of coal per 

 day, this makes her sphere of action 4500 marine miles or 1500 geographical 

 leagues, and her regulation provision of 700 tons would be enough for thirty days' 

 consuvnption at this rate. With the same number of furnaces, but increasing the 

 fires so as to attain a rate of 9 knots (which she has actually done), her coMsump. 

 tion is increased to 1560 kilogrammes per hour, or 37-, 440 per day, and the above 

 provision would serve for a consumption of more than 18 days, and a run of 

 4050 miles, or 1S50 leagues. With four furnaces she attained a speed of 11 knots, 

 averaging 41 tons of coal per day, and this would last for 15 days, and a run 

 of 3960 miles, or 1320 leagues. With six furnaces her mean rate was 12.4. knots, 

 and her consumption 94 tons, reducing her time to V^ days, and her run to 2235 

 miles or 745 leagues. With all eight furnaces going she reached a mean speed of 

 13.9 knots with a daily consumption of 1S8 tons, under which circumstances her 

 regular provision would last five days, and her run be reduced to 1668 miles 

 or 556 leagues. During her trial with eight furnaces, she maintained, by keeping 

 up her fires, for more than an hour a speed exceeding 14 kuots, her engine making 

 57 turns of the screw per minute ; and on the other hand, by reducing the action 

 of her engine to the lowest, the point it could not exceed without stopping alto- 

 gether, she slill reached a speed of 8 knots with only 12 turns in the minute. 



All this is very encouraging, but tliere is one point on which I must exercise 

 Bome reserve. Beyond doubt, the nautical qualities of the fhips, their speed, their 

 facility of evolution, the ease with which their engines accomodate themselves to 

 a number of combinations, the amount of resources of all kinds they can accumu- 

 late between their own sides, are important, or even the principal, conditions of 

 their military value; nevertheless, there is another question which, on the great 

 day of trial, will rise to the first rank in importance. I mean the power of their 



