For facility of carrying on the works, reliable bench marks, or reduced level stations, must be established at convenient distances along the route of the line, and from these and the fixed chain-pegs the correct line of formation level can be checked from time to time as the work proceeds. For ordinary earth or clay cuttings, the usual tools are picks and iron crow-bars for loosening, or _getting_ the material, and shovels for filling into barrows, carts, or waggons. For heavy earthworks, steam excavators are now largely employed. Great improvements have been made in this class of machinery, in the way of perfecting the method of excavating lifting, and filling the material into the earth-waggons. In nearly all rock cuttings the greater portion of the material has to be taken out, or loosened, by blasting with gunpowder, dynamite, or other explosive. The number and extent of the charges will depend upon the nature of the rock and its stratification, and also on its position 67 as regards proximity to buildings or residential property. Where the rock is loose, or disintegrated, the pieces can generally be readily separated by picks and bars without having to resort to any great extent of blasting. [Illustration: Fig. 57, 58, 59, 60, 61, 62, 63, 64, 65, 66] The first of the material excavated in the cuttings is generally conveyed in wheelbarrows to form the commencement of the adjoining embankments. When the wheeling distance becomes too far for economical barrow work, ordinary carts or three-wheeled carts, sometimes termed _dobbin carts_, are brought into operation where the cuttings and embankments are light; but where the earthwork is heavy, both in excavation and filling, a service or temporary road of light rails and sleepers is usually laid down to carry strong _tip_ earth-waggons. For moderate distances these waggons are hauled by horses, but for distances over three-eighths of a mile a small locomotive is more speedy and economical. Fig. 57 shows one form of dobbin cart; the wheels are made with good broad tyres, so as not to sink too deep into the soft ground, and the body being attached to the framework by a pivot or trunnion on each side, can be readily tilted over, and the earth tipped out, by releasing the holding-down catch. Where the ground is soft and wet, or of a very loose sandy nature, the work of hauling these dobbin carts is very heavy on the horses, and in such cases it soon becomes an advantage to lay down a service road of rails and sleepers. This service road is formed of light rails manufactured for the purpose, or old, worn rails no longer fit for main-line work, spiked down on to rough transverse wooden sleepers. The end of the embankment in course of formation, and where the earth is being tipped, is termed the _tip head_. Two or more roads are required at the tip head to form the embankment to its full width. Fig. 58 gives a sketch plan of a service road near the tip head. The width is shown as