For straight lines the ruling pen should be employed. In this implement, the nibs, as in the pen compasses are provided with a screw, by means of which the pen can be adjusted to form thick or thin lines as required. Care should be taken in the adjustment; for the thinnest line the points should only be in contact. If screwed too tightly the nibs may be bent and would have to be re-set. There is a limit to the thickness of line in individual ruling pens, which are made in varying sizes for fine or bold work. Bow and ruling pens should never be filled to the full capacity, as they are then liable to flood and blot the work. It is better also to charge the pen with the filler, which is usually provided with the ordinary liquid ink, or a brush; otherwise blotting may result. If the pen is filled by dipping, the nibs should be wiped dry on each occasion on the external faces. In use the ruling pen should be held as vertical as possible, with the nibs perfectly parallel to the edge of T or set square, any divergence from the vertical might result in a curve instead of the straight line required. If the nibs are at an angle with the ruling edge, the ink will not flow freely, and there is also a tendency to cut the surface. _Proportional Compass_ Another instrument of great use, though not so commonly in request, is the proportional compass, by means of which drawings are enlarged or reduced. It consists of two shanks furnished with points at each end, the shanks being slotted out centrally to form a slide. The adjustment is accomplished by a set screw which also forms a pivot, which, set at any of the marked divisions, assures the given proportion. _Tracings_ Tracing paper is largely in request, not only as a means of repeating details and units by transferring, but when copies of a drawing are required. It can be obtained in rolls varying in width, forty inch being generally useful, and in different surfaces, rough and smooth, the former being good for pencil work--the smooth being more suitable for ink tracings. When tracings of a more durable character are required they are made on linen, which for this purpose has a highly glazed surface on which the ink will not always run equally. This can be rectified by lightly rubbing the surface with French chalk and by adding a little ox gall to the ink. The latter is a useful agent in counteracting any greasiness of surface and is often necessary in colour work. _Conclusion_ The stimulus of competition is always healthy, and the necessity to attract has resulted generally in raising the standard, notably in forms of advertisement. The designer has not only to keep pace with modern conditions, but in some phases of work has also to anticipate future demand.