The semicircle on a sector in two books. Containing the description of a general and portable instrument; whereby most problems (reducible to instrumental practice) in astronomy, trigonometry, arithmetick, geometry, geography, topography, navigation, dyalling, &c. are speedily and exactly resolved. By J. T.

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Title: The semicircle on a sector in two books. Containing the description of a general and portable instrument; whereby most problems (reducible to instrumental practice) in astronomy, trigonometry, arithmetick, geometry, geography, topography, navigation, dyalling, &c. are speedily and exactly resolved. By J. T.
Author: Taylor, John, 1666 or 7-1687.
Publication: London :: printed for William Tompson, bookseller at Harborough in Leicestershire,; 1667.
Rights/Permissions: To the extent possible under law, the Text Creation Partnership has waived all copyright and related or neighboring rights to this keyboarded and encoded edition of the work described above, according to the terms of the CC0 1.0 Public Domain Dedication (http://creativecommons.org/publicdomain/zero/1.0/). This waiver does not extend to any page images or other supplementary files associated with this work, which may be protected by copyright or other license restrictions. Please go to http://www.textcreationpartnership.org/ for more information.
Subject terms: Mathematics -- Early works to 1800.; Navigation -- Early works to 1800.; Dialing -- Early works to 1800.
Cite this Item: "The semicircle on a sector in two books. Containing the description of a general and portable instrument; whereby most problems (reducible to instrumental practice) in astronomy, trigonometry, arithmetick, geometry, geography, topography, navigation, dyalling, &c. are speedily and exactly resolved. By J. T." In the digital collection Early English Books Online. https://name.umdl.umich.edu/A64223.0001.001. University of Michigan Library Digital Collections. Accessed May 18, 2024.

Pages

Sect. 2.

To describe an erect, direct South Dial. See Fig. 10.

Draw ABCD. a rect-angle parallello∣gram. Then make AE=EB=CF=FD=cos. of your latitude. And EF=AC=BD=sine of your latitude. Enter CF. in tang. 45. and lay down FK=FL=tang. 15. and FI=FM= tang. 30. Again, enter AC. in tang. 45. and lay down AG=BO=15. and AH=BN=tang. 30. with a ruler draw the lines EG. EH. EC. EF. EK. for the hour lines of 7. 8. 9. 10. 11. in the morning. and EO. EN. ED. EM. EL. for 5. 4. 3. 2. 1. afternoon, the line AEB. is for six and six. The line EF. for twelve.

The description of a direct North-Dial differs nothing from this, only the hour lines from Sun rise to six in the morning, and from six in the evening, until Sun set, must be placed thereon, by drawing the respective morning and evening hours beyond the cen∣ter as in the horizontal. See Fig. 11.