2026. Inclined fruit-walls seem to have been first suggested, about the beginning of the eighteenth century, by N.F.De Douillier, F.R.S., an able mathematician, author of a work entitled. Fruit-walls improved by inclining them to the Horizon, &c. Some walls were formed at Belvoir Castle on this plan, which Switzer informs us he went to see, but found them damp, and the trees liable to be injured by perpendicular frosts. De Douillier's work, as being the production of a speculative theorist (he was tutor to the Marquess of Tavistock), appears to have been rejected by Miller, Switzer, Lawrence, and the designers of gardens of that day, but it is replete with ingenuity and mathematical demonstration, and well illustrates the importance of sloping walls where they are to be protected by glass or gauze. In a communication to the Horticultural Society (vol. iv. p. 140.), by Stoffels, gardener at Mechlin, he states, 'that he had an opportunity of comparing the effect of a sloping and perpendicular wall in the same garden, for the growth of peach trees, and that the result was greatly in favour of the former.'
