A problem which is not an attractive one, but which has to be solved, is to arrange the proper method of supplying a fleet and maintaining its communications. In time of peace as well as in time of war there is a continuous consumption of the articles of various kinds used on board ship, viz. naval stores, ordnance stores, engineers' stores, victualling stores, coal, water, &c. If we know the quantity of each description of stores that a ship can carry, and if we estimate the progressive consumption, we can compute, approximately but accurately enough for practical purposes, the time at which replenishment would be necessary and to what amount it should be made up. As a general rule ships stow about three months' stores and provisions. The amount of coal and engineers' stores, measured in time, depends on the proceedings of the ship, and can only be calculated if we know during what portion of any given period she will be under way. Of course, this can be only roughly estimated. In peace time we know nearly exactly what the expenditure of ammunition within a given length of time--say, a quarter of a year--will be. For war conditions we can only form an estimate based upon assumptions. The consumption of provisions depends upon the numbers of officers and men, and in war or peace would be much the same. The greater activity to be expected in war would lead to more wear and tear, and consequently to a larger expenditure of naval stores. In peaceful times the quarterly expenditure of ammunition does not vary materially. In case we were at war, a single action might cause us to expend in a few hours as much as half a dozen quarterly peace allowances. There is a certain average number of days that a ship of a particular class is under way in a year, and the difference between that number and 365 is, of course, the measure of the length of time she is at anchor or in harbour. Expenditure of coal and of some important articles of engineers' stores depends on the relation between the time that she is stationary and the time she is under way. It should be particularly noted that the distinction is not between time at anchor and time at sea, but between time at anchor and 'time under way.' If a ship leaves her anchorage to run an engine-trial after refit, or to fire at a target, or to adjust compasses, or to go into dock--she burns more coal than if she remained stationary. These occasions of movement may be counted in with the days in which the ship is at sea, and the total taken as the number of days under way. It may be assumed that altogether these will amount to six or seven a month. In time of war the period under way would probably be much longer, and the time spent in expectation of getting under way in a hurry would almost certainly be considerable, so that expenditure of coal and machinery lubricants would be greatly increased.