The coloured decoration introduced in finishing the painting of the building is a subject which has been much discussed, and many suggestions have been made by persons generally received as authorities on the subject. The system adopted was proposed by Mr. Owen Jones, under whose active superintendence it has been carried out. That gentleman explained his reasons for its adoption, and the effect which he expected it to produce, in a lecture at the Institute of British Architects, on the 16th of December, 1850, some portions of which are submitted to our readers:-- "It is not necessary for me to describe the building, the painting of which we are now about to discuss, as it is well known to most of you by its marvellous dimensions, the simplicity of its construction, and the advantage which has been taken of the power which the repetition of simple forms will give in producing grandeur of effect; and I wish now to show that this grandeur may be still further enhanced by a system of colouring which, by marking distinctly every line in the building, will increase the height, the length, and the bulk. "The very nature of the material of which this building is mainly constructed, viz., iron, requires that it should be painted. On what principle shall we do this? Should we be justified in adopting a simple tint of white or stone colour, the usual method of painting iron? Now, it must be borne in mind that this building will be covered on the south side, and over the whole of the roof, with canvass, so that there can be but little light and shade. The myriads of similar lines, therefore, of which the building is composed, falling one before the other, would lose all distinctness, and form, in fact, one dull cloud overhanging the Exhibition. "A line of columns (as it may be seen even now at the building) would present the effect of a white wall, and it would be impossible, in the distance, to distinguish one column from another. This mode of painting would have the further disadvantage of rendering the building totally unconnected with the various objects it is to contain. "May the building be painted of a dark colour, like the roofs of some of our railway-stations? This, equally with the white method, would present one mass of indistinctness; the relief of the cast-iron would disappear, and each column and girder would present to the eye but a flat silhouette.