To man our ships in time of war three means are open: voluntary enlistment, draft or impressment, or employment of men enrolled in a naval reserve. It would be unreasonable to depend altogether upon the loyal and unselfish patriotism of necessitous men serving before the mast, and there is a chance that mere enthusiasm would not induce a seaman to join the navy if employment was being offered elsewhere at increasing rates of pay. Impressment under any name is unpopular. In its common form it is illegal, and the draft is ever a last resort and always a dangerous measure. Nothing, then, remains as a certainty but to turn towards the naval reserve as the best means of manning our fleet. In time of war not only would the men enrolled come forward willingly and be immediately available, but deserters would have the machinery of the law put in motion for their apprehension, and popular feeling would be as earnest in support of their arrest as it would be opposed to all attempts which enforced the arbitrary powers of draft or impressment.
No system exists abroad entirely suited to our necessities and our national instincts; but, generally speaking, that adopted in England comes nearest to what we should employ. Naturally our lake sailors, coasters, fishermen, and yachtsmen would form the main body of the reserve. These should be enrolled, divided into classes, be given each year a certain fixed sum of pay, with an increase for each day’s drill, and at stated times they should be embarked for great gun practice at sea, so they might learn something of man-of-war routine and discipline. The officers could be drawn from the merchant marine, from the graduates of the school-ships, and from former officers of the regular and volunteer services who are now in civil life.
FORCED DRAFT.
The subject of forced draft is of great importance, and, as a corollary of high-speed development, is being studied with keen interest. There are wide differences of opinion not only as to the proper systems, but even as to the value of the principle. The literature as yet is rather meagre, but an excellent compilation of existing material will be found in the latest publication of the Naval Intelligence Office.
“A forced draft in the furnaces,” explains the Marine Engineer of September, 1887, “can be generated in two ways: first, by exhausting the uptakes and funnels of the products of combustion, when a greater flow of air will necessarily take place through the fire-bars; and secondly, by increasing the pressure of the air in the furnaces beyond that of the atmosphere. The steam-blast in marine boilers is well known to engineers as a means of quickly getting up the steam after its pressure has dropped; but the locomotives on our railways afford a very good illustration of how boilers may be continuously worked under forced combustion through a jet of steam exhausting the smoke-box and funnel of the products of combustion. This system of creating a draft involves a very large expenditure of steam and water, and as it is a sine qua non in these days of high pressure that only fresh water should be used in boilers, and also as only a limited supply of this element can be carried in a ship, it follows that the plan of inducing a forced draft by means of a steam jet in the funnel cannot be well adopted in marine boilers.
“Mr. Martin, the inventor of the well-known furnace doors, substitutes a fan in the uptake for the steam jet, and so arranges his funnel that in the event of the forced draft not being required the gases of combustion arising from natural draft will not be impeded in their exit to the atmosphere. He claims for his invention that it does away with all necessity for closing in the stoke-holds or furnaces, and that in war-ships funnels could be dispensed with, as the gases and smoke could be discharged anywhere from the fans. He also claims that by his plan of producing a draft the boiler-tubes become much more efficient as heating surfaces, and that the ends of the tubes in the fire-box are not so liable to be burned away, and that therefore there will be less chance of the boiler leaking round the tubes. There appears to be some grounds for these latter assumptions, for it is a well-known fact that the tubes of locomotive boilers, which are worked, as we have seen, on the exhaust principle, do very much more work than those of marine boilers before they are ferruled or rolled. It can also be shown by a very simple experiment that when the gases are sucked or drawn through the tubes the flame extends a much greater distance along the tube than when the gases are driven through the tubes. In this latter case the flame impinges on the tube-plates before separating into tongues and entering the tubes; but when sucked through the tongues of flame commence at some little distance from the plate before penetrating the tubes, and the ends are not therefore burned as when the flame impinges directly on them. It may be urged, however, against Martin’s system that owing to the greatly increased volume of the products of combustion due to their temperature, fans of from three to four times the size of those used in other systems are required; also, that the uptakes have to be made larger and heavier to take in the fans; and lastly, that the fans themselves are likely to be quickly rendered inefficient through working in a temperature of at least a thousand degrees. These objections prove so formidable that up till the present time Martin’s plan of creating a forced draft has made little or no headway.
“The other plan for creating an artificial draft in marine furnaces is to force air into them by means of fans. This is done either by closing in the whole of the stoke-hold and filling it with air of a pressure greater than that of the atmosphere, or by pumping the air direct into the furnace. This latter is the usual practice in the mercantile marine, where economy of fuel is sought after. Mr. Howden seeks, by first heating the air, and then forcing it by means of fans into the furnaces and ash-pits, to insure a very rapid and complete combustion of the coal. His plan has been carried out in the Atlantic liner Ohio quite recently, and the results as published lead one to expect that with a little more progress in the direction in which he is working our ships will be driven across the Atlantic without the expenditure of any fuel whatever. The fact of heating the air to a temperature of two hundred degrees before it enters the furnace cannot go very far in affecting either the rapidity or the completeness of the combustion of the fuel, and it certainly cannot affect the economy. Where the fire-grate area is small compared with the total heating surface, good evaporative results are likely to be obtained; and in the Ohio the fire-grate area was certainly smaller than is usual for the same sized boilers fitted with forced draft. The trip of the Ohio to America has given somewhat different results to those of the official trials, and it is a question whether any saving in weight, either in the apparatus required to produce forced draft under this system, or in the economy of fuel to be derived from it, has been obtained more than exists in the system of closed stoke-holds.
“The only plan that seems to hold its own is the closed stoke-hold system, and the results that have been obtained with it in the navy are so satisfactory that Messrs. J. & G. Thomson are about to adopt it in the two large Inman liners they are now building; and also several other firms are about to introduce it in preference to all other plans for increasing the efficiency of their boilers and promoting greater economy. In the Royal Navy space and weight are of such vital importance that the boilers have to be constructed on principles the very reverse of those which exist in boilers specially designed for high evaporative work per pound of fuel; and it is not, therefore, to be wondered at that the consumption of fuel per indicated horse-power has not been reduced since the introduction of forced draft; but, on the other hand, the capabilities of the boilers have been expanded far beyond the expectations of a few years ago. In the mercantile marine there is no reason whatever why the system of closed stoke-holds for creating a forced draft should not combine economy with greater efficiency in the boilers.”
These conclusions are not universally accepted, as will be seen in the following extract from the article contributed by Assistant Engineer R. S. Griffin, United States Navy, to the Naval Intelligence Office publication mentioned at the beginning of this subject.