. The practical draughtsman's book of industrial design, and machinist's and engineer's drawing companion: forming a complete course of mechanical, engineering, and architectural drawing. . • metal, sufficiently large to allow ofa conical aper-ture, B, corre-sponding with therequired cone ofa pointed leadpencil. One sideof this projectionis slotted to re-ceive the cutting edge of the small knife, c, which is attached tothe inclined portion, d, of the metal block by the screw, e, passingthrough a slot in the knife. A short projection,^, is formed uponthe knife for the convenience of adjustment,
. The practical draughtsman's book of industrial design, and machinist's and engineer's drawing companion: forming a complete course of mechanical, engineering, and architectural drawing. . • metal, sufficiently large to allow ofa conical aper-ture, B, corre-sponding with therequired cone ofa pointed leadpencil. One sideof this projectionis slotted to re-ceive the cutting edge of the small knife, c, which is attached tothe inclined portion, d, of the metal block by the screw, e, passingthrough a slot in the knife. A short projection,^, is formed uponthe knife for the convenience of adjustment, and when set, it isheld in position by the two set-screws, g. A small handle isscrewed into the block at h, from behind, for the convenience ofholding the instrument when in use, and the end of this handle ishollowed to receive the small projection, f, on the knife, c, for thefacility of holding it when detached for the purpose of sharpeningthe edge. An adjustable guide, i, is secured by the pinchmg-screw, J, by one end, beneath the block, and is furnished vsdth twoarms, k, jointed on to the end of the rod of the guide, for em-bracing the pencil, l, during the cutting Fig. 2. In usmg this instrument, the pencil is simply passed betweenthe two guide-arms, K, and its end is inserted in the conical hole, is then turned round between the finger and thumb, and theknife-edge coming into contact with the end to be sharpened,quiekly pares off the material. By this simple apparatus an ex-cellent point is given to the pencil in a very short time, savingthe draughtsman from all the troubles and inconveniences ofblunt penknives and fractured lead. A mathematical drawing-pen consists of a pair offlat, tapered steel-blades, fixed to a handle of ivoryor ebony. The ink is contained between the blades^and flows out from between the points, the thicknessof line produced being dependent on the distanceasunder of the points, which distance is regulated bya pinching-screw. In or
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Keywords: ., bo, bookcentury1800, bookdecade1850, booksubjectmechanicaldrawing
