The Amateur Mechanic's Workshop; A Treatise Containing Plain and Concise Directions for the Manipulation of Wood and Metals. Including Casting, Forging Brazing, Soldering, and Carpentry

The Amateur Mechanic's Workshop; A Treatise Containing Plain and Concise Directions for the Manipulation of Wood and Metals. Including Casting, Forging Brazing, Soldering, and Carpentry

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1874 edition. Excerpt: ...the angles at the point where they cut equal four right angles." Take the small triangle E C D. The angles at C and D are each 45 (half the right angles at the corners of the square), then if it is true that the three angles of a triangle are together equal to two right angles, the angle at E must be a right angle (for we have taken from the triangle the two angles C and D, each of 45, and together 90 or one right angle, and so the one lefc must be the other), and we might take in turn each of the four small triangles in the same way, and thus should find at the point E, four right angles, as stated. It will thus appear that it is easy in many cases to draw two lines at a desired angle by very simple means--namely, with the ordinary two-foot rule and compasses alone. If an angle of 60 is required, it is only necessary to make a triangle of three equal sides, which is readily constructed as follows: Draw a line A B, Fig 120, six (any number of) inches in lengih, open a pair of compasses to that width and with one point at A, describe with the other an arc (part of a circle) as shown. Do the same from the other end of the line, and it will be found that the second arc cuts the first, and from the point at which they cut each other draw lines to the ends of that first drawn. You now have a triangle with equal sides, and each angle of 60. Divide the base line exactly in half and draw a line as dotted. This will divide the top angle into two exactly equal; you now, therefore, have an angle of 30. At the point D, too, you have thus raised a line, D C, perpendicular, or at right angles to A B, each angle at D being 901, and thus another useful lesson in Geometry has been learnt. Similarly, that useful angle of 45 has been shown to be obtained by...show more

Product details

  • Paperback | 56 pages
  • 189 x 246 x 3mm | 118g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 123653672X
  • 9781236536723