The carpet designer and colourist must have strict regard for the limitations of his medium, and in particular the limitations of pitch and of colour. He must know how to employ in the most effective manner, thirty shades or three, and what treatment is best for a floral design or an Oriental, in a fine or a coarse pitch. Of course, the same laws of colour harmonies and contrasts hold good for the carpet colourist, as for the artist in any other branches of applied art; but the carpet artist has his own particular problems, such as those that have been indicated, and such as arise, for instance, from the fact that carpets have wool surfaces and lie on the floor, and therefore bear quite a different relation to the decoration of a room than curtains or ceilings. Carpet colourings, apart from plains, may be analysed into self-colour effects, two-colour effects, and effects of three or more colours. Self-colour or tone-on-tone effects adapt themselves more easily to a scheme of decoration than carpets containing contrasted colours. It seems to be a fact that the carpet is about the last thing to be thought of in a scheme of decoration. It need not be discussed whether it ought to be so or not. The walls, curtains, tiles, etc., are decided upon before the question of the colour of the carpet arises. In such a case, if a harmonious effect is to be ensured, there may be little choice left in the matter; and a self-coloured carpet may be either the easiest way out of the difficulty, or an artistic necessity. Certainly it is easier to furnish to; and, if it does mean a certain want of ambition in the decorative scheme, it is simple and satisfying. Self-coloured carpets are also eminently suitable for small rooms, especially bed-rooms, on the one hand, and for theatres and music halls on the other, perhaps because one colour is more restful than several. The number of shades used varies from two to five, according to the simplicity or boldness of the design. More than five are certainly undesirable, as it becomes impossible to get steps of shades without approaching a white at the top and a black at the bottom; and, indeed, some of the most effective self-colours are made in three shades only. Two-tone effects of contrasted colours are not greatly used. They are sometimes employed in small designs, with two colours only, or three (one and a contrasting pair), but more often in bold designs of the Empire, Adam, or Wedgwood style, with three or four shades of one colour, upon a ground, or working against a pair of shades, of another; but effective combinations on these lines are rare. By far the largest proportion of carpets made are multi-coloured; and nearly every style and fabric is adaptable to treatment in this way.