The machinist and tool maker's instructor, containing an easy method of calculating and laying out difficult work in the machine shop .. (1896)
Genung, Edward. [from old catalog] · New York [Press of J. B. Savage, Cleveland] · leaf 145
t of the angle BOB. In the table of secants we findopposite 21° 48 the decimal 1.077, which, multiplied by theradius 3% = 4.0387, or say 4.039 for the length O B, asshown. Now as A C is always at right angles to B O, then wehave a right angled triangle A O B, figures 12 and 13. In thelatter figure… … THE MACHINIST AND TOOL MAKERS INSTRUCTOR. 141 below the pitch line, forming two separate right angled trian-gles : the one above the pitch line for finding the angle to turnthe pinion, and the one below the pitch line for finding theangle to cut the teeth. As A C is 90° from O B and the length is…
Machinery
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![An illustration from Athanasii Kircheri e Soc. Jesu Mundus subterraneus, : in XII libros digestus; quo divinum subterrestris mundi opificium, mira ergasteriorum naturae in eo distributio, verbo [Pantamorphon] protei regnum, uniuersae denique naturae majestas & divitiae summa rerum varietate exponuntur, abditorum effectuum causae acri indagine inquisitae demonstrantur, cognitae per artis & naturae conjugium ad humanae vitae necessarium usum vario experimentorum apparatu, necnon novo modo & ratione applicantur (1678)](https://img.insideoutlibrary.com/img/200/ia-athanasiikircher00kirc_4-77-0.webp)
