Finally, the work of building the line approached completion, and it became necessary promptly to settle the long-deferred question of a method of applying motive-power. Some of the directors and their advisers still advocated the use of horses; many thought stationary hauling-engines preferable; and the remainder were, almost to a man, undecided. The locomotive had no outspoken advocate, and few had the slightest faith in it. George Stephenson was almost alone, and the opponents of steam had secured a provision in the Newcastle & Carlisle Railroad concession, stipulating expressly that horses should there be exclusively employed. The directors did, however, in 1828, permit Stephenson to put on the line a locomotive, to be used, during its construction, in hauling gravel-trains. A committee was sent, at Stephenson's request, to see the Stockton & Darlington engines, but no decided expression of opinion seems to have been made by them. Two well-known professional engineers reported in favor of fixed engines, and advised the division of the line into 19 stages of about a mile and a half each, and the use of 21 fixed engines, although they admitted the excessive first-cost of that system. The board was naturally strongly inclined to adopt their plan. Stephenson, however, earnestly and persistently opposed such action, and, after long debate, it was finally determined "to give the traveling engine a chance." The board decided to offer a reward of £500 for the best locomotive-engine, and prescribed the following conditions: 1. The engine must consume its own smoke. 2. The engine, if of 6 tons weight, must be able to draw after it, day by day, 20 tons weight (including the tender and water-tank) at 10 miles an hour, with a pressure of steam on the boiler not exceeding 50 pounds to the square inch. 3. The boiler must have two safety-valves, neither of which must be fastened down, and one of them completely out of the control of the engine-man. 4. The engine and boiler must be supported on springs, and rest on 6 wheels, the height of the whole not exceeding 15 feet to the top of the chimney. 5. The engine, with water, must not weigh more than 6 tons; but an engine of less weight would be preferred, on its drawing a proportionate load behind it; if of only 4-1/2 tons, then it might be put only on 4 wheels. The company to be at liberty to test the boiler, etc., by a pressure of 150 pounds to the square inch. 6. A mercurial gauge must be affixed to the machine, showing the steam-pressure above 45 pounds to the square inch. 7. The engine must be delivered, complete and ready for trial, at the Liverpool end of the railway, not later than the 1st of October, 1829. 8. The price of the engine must not exceed £550.