weight) of cement was transported to the tunnel from Hull. During August 1838, James Wood, the chairman of the Manchester and Leeds Railway, laid the first brick in a ceremony. The original contractors were Evans, Stewart and Copeland. At the peak of construction, a workforce of between 800 and 1,250 men and boys was active, aided by about 100 horses and 13 stationary steam engines, which were used to remove material from the shafts. The bedrock was hewn using physical strength and hand tools, illuminated only by candlelight. At an early stage of track laying, the rails were laid directly onto excavated rock, but conventional wooden sleepers were also used. The spoil was used for other purposes, including in the construction of Blackpool Promenade. Alignment of the tunnel was achieved by drilling 14 vertical shafts to provide survey points. When the tunnel was complete, two shafts were sealed and the remaining 12 were retained as ventilation. The ventilation shafts were up to deep. During the tunnel's service life, No.6 was sealed after rock falls. Progress on construction was slower than expected; the bedrock and blue shale through which it was bored proved to be harder to excavate than anticipated. In March 1839, because of slow progress, the original contractors were dismissed and George Stephenson took over, after which the pace of work increased until a strike of the bricklayers occurred in March 1840. The last brick was laid on 9 December 1840. Summit Tunnel should have opened on New Year's Eve 1840; but the opening was delayed after the discovery of a defective invert, from one end which had displaced the central track drain. After repairs, the tunnel was officially opened by Sir John Frederick Sigismund Smith, the government inspector of railways on 1 March 1841. Summit Tunnel cost £251,000 and the loss of 41 lives. The cost was far greater than the railway company expected. The southern portal of the tunnel was grade II listed in 1986. Incidents The tunnel closed for the first eight months of 1985 following a fire that generated sufficient heat to vitrify sections of its outer brickwork. The build up of heat in the surrounding ground led to a 'false spring'; many plants produced flowers and buds as the warm soil triggered new growth. Damage to the tunnel lining was minimal which was attributed to heated gases from the fire escaping through the ventilation