For a map to look well two things are all-important, neatness and clearness; both of these may nearly always be secured by drawing on a large scale, bearing in mind what has been said about crowding the detail, etc., and carefully considering how much reduction the original can stand. This last point is of vital importance, for an over-reduced map is an abomination; we have seen really good maps absolutely ruined by this stupid error. The inexperienced author should study the methods pursued by Prof. Yapp in Figure 37. For comparison, the simpler way adopted by Mr. Wilson may be studied (_Annals of Botany_, 1911, Vol. 25). [Illustration: Figure 37. A Map of the Fenland by Prof. Yapp. (_New Phytologist_, 1908, Vol. 7)] GRAPHS OR CURVES. Simple though it be, the plotting of a curve for reproduction requires thought and care. In the first instance, the curve is drawn on squared paper, and the question naturally arises--To what extent are the squares to be represented? If it be desired to reproduce all the lines, say the paper is ruled in millimetres, a half-tone may be employed, or all these lines can be ruled over in black ink where the reproduction by line block is possible. It is, however, seldom necessary to represent all the smallest squares; it will generally be found that the centimetre squares are sufficient. If the original be plotted on paper which is ruled in pale blue, it can be reproduced by line block without re-drawing, since the blue will photograph as white with the plates commonly used; all the essential lines and curves must, of course, be in black. If, however, the rulings of the squared paper are in red, yellow, or dark blue, a tracing must be made. The horizontal and vertical sides should be ruled with a broad black line, but the internal intersecting lines should be much thinner. The actual curve may be in a continuous line if one only be shewn on the graph; if more are drawn, then each must be different, the obvious variations being the thick continuous line ---- the thin continuous line ----, dashes either thick or thin ---- ---- ----, dots . . . . . , and finally combinations of dots and dashes ---- . ---- . ---- . Owing to the difficulty which some experience in drawing freehand a continuous line, the plot should be made twice the linear size of the intended reproduction. A good rule to follow in drawing lines is to keep the eye fixed on the point where the line is to end, the hand will then guide the pen in the right path, especially after a little practice. In many cases the ruler may be used, not only for straight but also for curved lines, for good curve rules may be purchased. In order that the figure may look neat, the lines should be of an even thickness throughout their length; this is easily accomplished by means of a ruling pen.