The course consists of two parts,—the one relating to surveying processes exclusively, the other to the uses made of the plans and maps prepared by such processes, for engineering purposes.
Under the first of these divisions the officers are practically instructed in astronomical, general, special, and reconnoitring surveying, including the accurate delineation of the inequalities of ground by levelling and by contours traced instrumentally, and also the giving reliefs to hill forms by sketching with the pen and drawing with the brush.
Under the second division they are exercised in the adaptation of works of fortification to contoured sites, and in the selection and survey of lines of communication by roads, railways, and canals, and in drawing up projects for their execution.
Astronomical Surveying.
The officers are taught the construction and use of astronomical instruments, and are practised in making observations with them. They study from published works and memoranda printed at the establishment, the most useful problems for finding the time, the latitude and longitude, the direction of the meridian, and the variation of the compass.
Examples of each problem are worked out by them from their own observations or from observations made in their presence.
The use of meteorological instruments and the reductions of the observations made with them are also practised.
General Survey.
As a preliminary exercise in drawing each officer constructs a plate of scales from data supplied to him. For particular information on the delicate and powerful instruments and apparatus which have been used in great national surveys, and which cannot be studied in the establishment observatory, the officers are referred to published works; and they are instructed in the adjustments, the unavoidable errors of construction, and the powers of the instruments put into their hands for the execution of their survey course.
The general survey comprises: