Everyone connected with the land, be he market gardener, nurseryman, or farmer, should make himself acquainted with the principles of land surveying and measuring in so far as they relate to his business. A knowledge of the art will not only be useful in itself but will prevent anyone from making serious miscalculations as to areas, and the quantities of produce to be obtained from them. Such ground operations as levelling, digging, trenching, draining, etc, can be measured up to a nicety, and the cost of the work estimated very closely in advance. In the case of wet or heavy land, a knowledge of surveying and levelling will enable the market gardener or farmer to decide without any possibility of mistake the lowest part of his land, towards which it may be advisable to run drains or to dig trenches or ditches for drainage purposes. If walls, fences, greenhouses, or buildings of any description are to be erected, it is advisable to go over the land - survey it - to discover the most suitable sites or levels for the intended operations. Mensuration is so closely bound up with surveying operations that a knowledge of it is indispensable, and will be found of great advantage. Thus, if it is desired to heat a glass structure that is intended for the cultivation of stove or greenhouse plants, a certain quantity of hot-water piping will be necessary to supply sufficient heat, according to the cubic capacity of the greenhouse. The cubic contents of any glasshouse or other building are easily arrived at by mensuration, and this knowledge enables one to know almost exactly the quantity of piping necessary for any particular house. In the same way the area or contents of any building or structure, pipes, boilers, tanks, water pots, flower pots, etc, may be found. And if repairs are necessary it will be easy to estimate the quantities of paint, putty, bricks, timber, etc, required.

In that branch of horticulture known as " landscape gardening", a goorl knowledge of land surveying and levelling, and mensuration, is almost essential; otherwise the "landscape artist" will have to employ the services of a professional surveyor whose knowledge of horticultural matters may be nil. The landscape gardener has often to deal with the laying out of large or small areas of land and water, and he may have to convert a level meadow into an undulating garden with lakes and ponds arranged for landscape effect. Work of this description entails a good deal of labour and expense, and if a man has' no knowledge of surveying or mensuration he may very easily underestimate or overestimate the cost of transforming a piece of land from one state into another.

Surveying chain showing brass markers in position.

Fig. 398. - Details of Surveying Chain. A, Handle; s, Swivel.