We have thus briefly reviewed the development of our railways to show what they are, and how they came to be what they are, before describing the processes of building, in order that the reasons may be clearly understood why we do certain things, and why we fail to do other things which we ought to do. In the building of a railway the first thing is to make the surveys and locate the position of the intended road upon the ground, and to make maps and sections of it, so that the land may be bought and the estimates of cost be ascertained. The engineer's first duty is to make a survey by eye without the aid of instruments. This is called the "reconnoissance." By this he lays down the general position of the line, and where he wants it to go if possible. Great skill, the result of long experience, or equally great ignorance may be shown here. After the general position of the line, or some part of it, has been laid down upon the pocket map, the engineer sends his party into the field to make the preliminary survey with instruments. In an old-settled country the party may live in farm-houses and taverns, and be carried to their daily work by teams. But a surveying party will make better progress, be healthier and happier, if they live in their own home, even if that home be a travelling camp of a few tents. With a competent commissary the camp can be well supplied with provisions, and be pitched near enough to the probable end of the day's work to save the tired men a long walk. When they get to camp and, after a wash in the nearest creek, find a smoking-hot supper ready--even though it consist of fried pork and potatoes, corn-bread and black coffee--their troubles are all forgotten, and they feel a true satisfaction which the flesh-pots of Delmonico's cannot give. One greater pleasure remains--to fill the old pipe, and recline by the camp-fire for a jolly smoke. [Illustration: Engineers in Camp.] A full surveying party consists of the front flag-man, with his corps of axe-men to cut away trees and bushes; the transit-man, who records the distances and angles of the line, assisted by his chain-men and flag-men; and lastly the leveller, who takes and records the levels, with his rod-men and axe-men. The chief of the party exercises a general supervision over all, and is sometimes assisted by a topographer, who sketches in his book the contours of the hills and direction and size of the watercourses. One tent contains the cook, the commissary, and the provisions; another tent or two the working party, and another the superior engineers, with their drawing instruments and boards. In a properly regulated party the map and profile of the day's work should be plotted before going to bed, so as to see if all is right. If it turns out that the line can be improved and easier grades got, or other changes made, now is the time to do it.