'I intended to have given a figure to show the results of the pressure of the weight of all the leafage on a great lateral bough in modifying its curves, the strength of timber being greatest where the leverage of the mass tells most. _But I find nobody ever reads things which it takes any trouble to understand, so that it is no use to write them._' In a higher tone he had once announced the aim and principle of his book, claiming for it a difference from most books, and 'a chance of being in some respects better for the difference, in that it had not been written either for fame, or for money, or for conscience' sake, but of necessity.' 'I saw an injustice done and tried to remedy it. I heard a falsehood taught and was compelled to deny it. Nothing else was possible to me.' In that good time there was no question as to whether people would or would not take the trouble to understand. They were taught what the teacher deemed to be true, and the risk was on their own heads if they neglected the teaching. It was of use to write then, intelligibly or unintelligibly, truly and wholly; but this was before Mr. Ruskin had strayed very much from his road, or broken off, breathless and worn out, from a journey, doubled by aberrations, rendered wearisome by the most wilful wandering, and stopped at last,--not perfected. In extenuation of the delay in the completion of the work, the author pleads his many employments during five years:--his book on the _Elements of Drawing_; his addresses at Manchester, and his examination, 'with more attention than they deserved,' of some of the theories of political economy referred to in those addresses; the Manchester Exhibition, 'chiefly in its magnificent Reynolds' constellation;' a visit to Scotland, to look at Dunblane and Jedburgh, and other favourite sites of Turner's; and the arrangement of the Turner drawings, the property of the nation, for the trustees of the National Gallery. To this last task Mr. Ruskin set himself with characteristic enthusiasm. In the lower room of the National Gallery, when he began his work, there were 'upwards of nineteen thousand pieces of paper drawn upon by Turner in one way or other,'--many on both sides, some with four, five, or six subjects on each side,--'some in chalk, which the touch of the finger would sweep away, others in ink rotted into holes, others eaten away by damp and mildew, and falling into dust at the edges, in cases and bags of fragile decay, others worm-eaten, some mouse-eaten, many torn halfway through, numbers doubled (quadrupled I should say) into four, being Turner's favourite mode of packing for travelling; nearly all rudely flattened out from the bundles in which Turner had finally rolled them up and squeezed them into his drawers in Queen Anne Street' In the edges of these flattened bundles lay the 'dust of thirty years' accumulation, black, dense, and sooty.' With two assistants, Mr. Ruskin was at work,