Practical engineering drawing and third angle projection, for students in scientific, technical and manual training schools and for ... draughtsmen .. (1897)
Willson, Frederick Newton, 1855-1939 · Princeton, N.J., The author · leaf 48
tude G X toward the focus. If astring of length G X be fastened at G, stretched tight from G to any point B, by putting a pencilat B, then the remainder B X swung around and the end fastened at F, it is then, evidently, asfar from B to F as it is from B to the directrix; and that relation will… … 127. For the hyperbola, (Fig. 82), the construction is identical with the i^receding, except thatthe string fastened at / runs down the hypothenuse and equals it in length. 128. Referring back to Fig. 35, it will be noticed that the focus and directrix of the jjarabolaare there omitted; but the…
Mechanical drawing · Lettering
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
