A treatise on surveying and navigation: uniting the theoretical, the practical, and the educational features of these subjects (1852)
Robinson, Horatio N[elson], 1806-1867. [from old catalog] · Cincinnati, J. Ernst · leaf 26
s 30°, then the line AHplaced on a scale, will represent the tangent of 30° to the radius CA,and thus any other tangent can be laid down on the same scale. The scale of chords and sines, as well as the scale of equal parts,are to be found on the SECTOR. The sector is commonly made of ivory, and… … The figure before us represents one side of a sector with the planescale only upon it. More than one scale can be put on to a side,but we represent but one to avoid confusion. The scale must be alike on both arms — and it must commenceexactly at the joint — hence when near the center the different…
Surveying · Navigation
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