d. i |17. Fig. 8 is a perspective view show- 18. We have here used in Fig. 8 three ing the manner of applying the twist and rules simply for the convenience of illus- parallel rules of Fig. 7. 15 11 6, is the tration. In practice, many may be used. ■extradosal helix whose exact length and Sometimes… … voussoir treated. However, enough of these should always be used to exactly determine the warped helicoids. 19. This method of determining the that of its parts, 15 11 and 11 6, are warped helicoids will overcome Professor taken from the development (Fig. 6), Hyde's objection to the ordinary method…
Engineering
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