In view of the peculiarly advantageous circumstances detailed in the previous chapter, the British subsidy scheme is from the pecuniary point of view less imposing, and from the practical point of view far more comprehensive than any other scheme yet attempted elsewhere. The British War Department favours in general the use of vehicles intended to carry in active service useful loads of about three tons, but as the machines also have to take four men and a considerable quantity of kit and stores, they correspond to ordinary industrial vehicles of four tons capacity. There is a parallel, but much smaller, requirement, for 30-cwt. vehicles corresponding to the ordinary commercial two tonner and capable of higher speeds than are desirable with heavier machines. These lighter cars are intended for use behind mobile and fast-moving troops, while the heavier type are for the service of the infantry, and for the carriage of ammunition supplies. In each case, the total amount of subsidy paid is from £110 to £120. A portion of this takes the form of a cash payment when the vehicle is accepted, while the remainder is an annual payment spread over a period of three years, and is conditional on periodical inspection revealing the satisfactory condition of the machine subsidised. The agreement also provides that in the event of the War Department desiring to commandeer the vehicle in time of war, a very liberal price shall be paid to the owner, this price being of course dependent to some extent on the age of the machine. The correct amount is arrived at by deducting from the first cost of the car a certain regular percentage intended to represent the depreciation in value during every half year of normal service. After this deduction has been made, the resulting figure is increased by an agreed percentage of itself, the final result being that the price paid for any car under about two years old is very near, if not quite equal, to the original first cost. The first move made in the direction of a subsidy scheme in Great Britain dates back to 1908. At that time it was believed that light steam tractors best filled military requirements, and a number of these were registered, the nominal payment of £2 per annum being made to their owners. The industrial petrol vehicle was at this time passing out of its period of probation, and it was not long before the military authorities came to the conclusion that it represented a more useful type, in view of the nature of the particular emergencies against which they were chiefly called upon to guard. The ordinary steam-propelled vehicle was open to certain objections, the principle of which is the fact that its carrying capacity of fuel and water is limited, and the latter must necessarily be replenished at fairly frequent intervals. This is no great drawback in commercial work, but might be a very serious matter indeed in times of war, when men and horses have a prior claim on a possibly limited water supply.