Mechanical drawing self-taught: comprising instructions in the selection and preparation of drawing instruments. Elementary instruction in practical mechanical drawing. Together with examples in simple geometry and elementary mechanism, including screw threads, gear wheels, mechanical motions, engines and boilers (1889)
ntersection is termedthe axis of the ellipse. In an ellipse there are two points situated upon the (34 MECHANICAL DRAWING SELF-TAUGHT. line representing the major axis, and which are termedthe foci when both are spoken of, and a focus whenone only is referred to, foci simply being the pluralof… … Fig- 75- fine twine is passed ; a pencil point, C, is then placedin the loop and pulled outwards, to take up the slackof the twine. The pencil is held vertical and movedaround, tracing an ellipse as shown. Now it is obvious, from this method of construction,that there will be at every point in the…
Mechanical drawing
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