I shall not fatigue my reader with any further description: he must now try and make out the corresponding parts of the ground-plan and section for himself. But perhaps he may stumble at the threshold, not knowing what a section is; the term profile would have been better, for that means a vertical section. It may serve to convey an idea of a profile of a hill, if the reader will call to mind the appearance it would present in hazy weather, when nothing but the outline is visible; or, referring to the ground plan in plate XIII., let him conceive the hills there represented to be cut away from the dotted line, A B, so as to leave the face of the remaining parts of the hills perpendicular: this face would then present the exact appearance of the profile given in the plate.

By a little attention to what has been said above, I think the student will be able to comprehend the nature of a ground plan of hill features, with its corresponding section, as here shown.

METHODS OF SHADING HILLS, ETC.

The shading of hills may be performed by using a blacklead pencil, with a pen, by washes of Indian ink, or neutral tint, &c.

There are two modes of expressing inclinations of ground with the pen or lead pencil, distinguished as the vertical and horizontal manners. In this country, opinion is divided as to which method is the best for general purposes. The vertical mode, as already stated, assumes the pen strokes to represent such minute rills as water forms when trickling down the slope of a hill. The horizontal manner marks the contours of hills by waving lines, each line continuing on the same level while following every undulation of the ground; as, in some hilly parts of this country, sheep paths may be observed, often covering the entire faces of steep

F

declivities, at a few feet apart, and horizontally pursuing their windings. Plate XIV. shows the same hill, drawn in both the horizontal and vertical styles.

Mr. Burr, the Professor of Military Surveying at Sandhurst, showed me recently what I think a very ingenious and striking way of conveying a just idea of this style, by means of a model in plaster of Paris, representing some hilly ground. He had enclosed his model in a wooden box, which was then filled with water. A scale, divided into quarters of an inch, having been placed upright in the box, the water was allowed to run off through a hole near the bottom, by a quarter of an inch at a time, as indicated by his scale. At every successive fall of the water, he traced lines on the model, indicating the curves shown upon its surface by the successive lowering of the water. When the operation was completed, the surface of his model exhibited a number of lines, all of course perfectly horizontal; closing upon each other where the hills were steep, and diverging again where the slopes became more gentle. A model so prepared is easily represented on paper, and with great accuracy; and I cannot do better than recommend those who are desirous to obtain a thorough knowledge of ground, to consider the horizontal method with attention, as it reduces the delineation of hills to something of a fixed principle. In practice, either or both of the styles may be used at the pleasure of the draftsman, or as may be best suited to the nature of the ground he wishes to pourtray. The sketch in plate V. is a specimen of the horizontal manner of shading.

The vertical style of sketching hills used to be generally practised in the British service; so much so, that I do not think a single officer of the Royal Staff Corps employed the horizontal manner; but of late years the latter has been in favour at our military colleges, and now bids fair entirely to supersede the vertical method. A very able military sur