The practical draughtsman's book of industrial design and machinist's and engineer's companion : forming a complete course of mechanical, engineering and architectural drawing . orfrom a scale ; and also, as the name implies, fordividing lines and circles into equal parts. Forthis latter purpose, it is on the trial and errorsystem that they are employed, if at all. Dividersconsist of a pair of legs, pointed at one end, andjointed together at the other; the points, and aconsiderable portion of the leg, being of steel,whilst the shanks are of brass, German silver, or composition-metal. German si
The practical draughtsman's book of industrial design and machinist's and engineer's companion : forming a complete course of mechanical, engineering and architectural drawing . orfrom a scale ; and also, as the name implies, fordividing lines and circles into equal parts. Forthis latter purpose, it is on the trial and errorsystem that they are employed, if at all. Dividersconsist of a pair of legs, pointed at one end, andjointed together at the other; the points, and aconsiderable portion of the leg, being of steel,whilst the shanks are of brass, German silver, or composition-metal. German silver or composition-metal is to be preferred tobrass, as the latter gets soiled sooner, contracting a species ofgreasiness from the atmosphere and perspiration of the hand,accompanied by an unpleasant odour. The joint of the dividers,and of all compasses, must be made free from all cross play, orlateral looseness. The most ordinary kind are fastened simplyby a common screw. We have, indeed, seen some very ordinary BOOK OF INDUSTRIAL DESIGN. 187 5nes riveted together. The better kind have a steel pin passedthrough the leaves of the joint, upon which a flat brass or other. metal nut is. passed, at the further side. This nut haa two smallholes upon its face, for the introduction of the points of a turn-screw, to be met with in most sets of instruments. The joint-leaf of one leg of a pair of compasses is usually of steel, as thisarrangement gives a smoother action than when both sides of thejoint are of the same metal. The better kind are also made withtwo steel leaves on one side, which are introduced between threebrass ones on the other; but some have only one leaf on one side,and two on the other. A perfect compass-joint is a thing seldommet with, and draughtsmen are continually subject to annoyance,arising from the inequality of action of the joints of their com-passes. After someFiff-a little usage, these parts invariably im-bibe the bad habit ofan alternate tightnessand loose
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Keywords: ., bookcentury1800, booksubjectarchitecturaldrawing, booksubjectmec
