Before proceeding to carry out the works of any line of railway, it is necessary to prepare a complete plan and section of the line, showing the route to be followed and the position of the various curves, gradients, and principal works. Within certain limits, the course of the line may have to be slightly modified as the work proceeds, in consequence of ground turning out unfavourable, river-crossings treacherous, or of sites involving so many contingent alterations that it is found better to avoid them altogether. The route should, however, be so carefully studied out before completing the final plan and section, as to leave only minor deviations of line and level to be dealt with in the actual carrying out of the work. The promoters of lines in the United Kingdom obtain valuable assistance from the ordnance maps, which give full and reliable information regarding the position of all roads, rivers, and boundaries of counties, parishes, and townlands. In many parts abroad 4 local maps are scarce, and not always accurate, and engineers have to depend principally on their own surveys, and rely upon the resident local authorities for any particulars as to divisions of territory. On some of our great colonial plains, and out in the far west of America, a line may be laid out for miles without a single landmark to localize it on a plan; but careful setting out, and the relative levels of the ground and gradients, as shown on the section, will always indicate the correct position of any portion of the work. Both at home and abroad complete plans and sections of any proposed railway must be deposited with the proper Government authorities, and must be approved and sanctioned by them before permission can be obtained to proceed with the works. The regulations regarding the scale and general arrangement of these plans and sections vary in different countries, and are subject to modification from time to time. Each country has its own special enactments relative to the method of dealing with roads, rivers, streams, and public and private property proposed to be interfered with in the construction of any line, and a knowledge of these is absolutely necessary for the promoters of any new scheme, inasmuch as some of the requirements may, in certain instances, influence the precise route to be selected. The English Government has passed several Acts of Parliament setting forth the general conditions which must be complied with in the construction of any railway in the United Kingdom. These conditions, or standing orders, relate both to the acquirement of land and property, the size and description of works for public or private accommodation, and the inspection and official approval of the undertaking when completed. These fixed regulations are alike valuable to the promoters and to the public; the former are informed of the principal points with which the scheme must conform, and the latter know the limit of their legal demands.