The model, from which this cut has been executed, is on the scale of two inches to one foot; so that the head of the harrow is three feet wide from one side of the bar to the other, externally. These bars are four inches square; five feet long; and, to prevent them from being split, they are contrived lengthwise, instead of being in a transverse direction. The mould-boards are four feet two inches in length, ten inches in depth, and two in thickness: they extend 11 inches beyond the bars, in order that the stones (which are brought to the surface by the teeth of the harrow) may be drawn into a smaller compass. These mould-boards are, farther, shod with an iron-bar, and lined with a plate of the same metal, to the height of the spot where they are marked black, in the cut above annexed; and such parts of this delineation, as are represented of a deeper colour, distinguish the iron from the wood-work. The teeth are one foot in length from the inferior side of the bars to their points, which ought to be steeled: they are 114 inch square, and are fixed by means of strong nuts and screws, with collars both on the upper and lower side of such bars.
Mr. Harriott's road-harrow is drawn by two horses abreast: the outside animal is led by a boy on that quarter; while the other horse walks in the proper path, and a man keeps the harrow steady by the handles; consequently they take one inside and one outside quarter in their progress, and the remaining two quarters in their return.
By this excellent machine, a man, boy, and two horses, may with ease repair three miles in length, in one day; harrowing down the quarters, and drawing the stones together, which are dropped into the ruts, by means of the mould-boards, in a more effectual manner than if they were stubbed in by a man. Lastly, the work is performed not only more expeditiously, but also at one-tenth part of the expence incurred, when the roads are repaired by manual labour.
In the 8th volume of the Repertory of Arts, &c. we meet with an account of a contrivance for preventing the wheels of carriages from making ruts in roads,
