A few short stretches of 4ft. 8½in. track are in use in Spain, but the majority of the lines are constructed to a gauge of one metre (3ft. 3½in.). In Russia, the railway tracks are built to a gauge of 5ft., and although between Russia and Germany carriages with telescopic axles have been experimented with in the effort to solve the vexed problem of through running, these have not turned out to be a success in actual practice. The convenience of the 4ft. 8½in. gauge is illustrated by the fact that no less than 70 per cent, of the world's railways are constructed to this gauge—a dimension originally determined by the width of the antiquated trucks employed on the old horse wagon-ways of North-east England. The remaining 30 per cent. of the world's railway trackage varies from 5ft. 6in. to 1ft. 3in. gauge.