IIII. To find the suns Altitude by a back ob∣servation,
Skrew the Turning sight to the leg cen∣ter,
The triangular quadrant, or, The quadrant on a sector being a general instrument for land or sea observations : performing all the uses of the ordinary sea instruments, as Davis quadrant, forestaff, crosstaff, bow, with more ease, profitableness, and conveniency, and as much exactness as any or all of them : moreover, it may be made a particular and a general quadrant for all latitudes, and have the sector lines also : to which is added a rectifying table to find the suns true declination to a minute or two, any day or hour of the 4 years : whereby to find the latitude of a place by meridian, or any two other altitudes of the sun or stars / first thus contrived and made by John Brown ...
About this Item
- Title
- The triangular quadrant, or, The quadrant on a sector being a general instrument for land or sea observations : performing all the uses of the ordinary sea instruments, as Davis quadrant, forestaff, crosstaff, bow, with more ease, profitableness, and conveniency, and as much exactness as any or all of them : moreover, it may be made a particular and a general quadrant for all latitudes, and have the sector lines also : to which is added a rectifying table to find the suns true declination to a minute or two, any day or hour of the 4 years : whereby to find the latitude of a place by meridian, or any two other altitudes of the sun or stars / first thus contrived and made by John Brown ...
- Author
- Brown, John, philomath.
- Publication
- [London] :: To be sold at [his, i.e. Brown's] house, or at Hen. Sutton's ...,
- 1662.
- Rights/Permissions
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- Subject terms
- Quadrant.
- Dialing.
- Mathematical instruments.
- Cite this Item
-
"The triangular quadrant, or, The quadrant on a sector being a general instrument for land or sea observations : performing all the uses of the ordinary sea instruments, as Davis quadrant, forestaff, crosstaff, bow, with more ease, profitableness, and conveniency, and as much exactness as any or all of them : moreover, it may be made a particular and a general quadrant for all latitudes, and have the sector lines also : to which is added a rectifying table to find the suns true declination to a minute or two, any day or hour of the 4 years : whereby to find the latitude of a place by meridian, or any two other altitudes of the sun or stars / first thus contrived and made by John Brown ..." In the digital collection Early English Books Online. https://name.umdl.umich.edu/A29764.0001.001. University of Michigan Library Digital Collections. Accessed May 3, 2024.
Pages
Page 9
(or center to the degrees on the move∣able leg) and put one of the object sights, in the hole by 00. on the outer edge of the crosse peece, and set the edge of it just against the stroke of 00, or you may use the sliding object sight and set the edge or the middle of that, to the stroke of 00, as you shall Judge most convenient; and the horizon sight to the moveable leg, then observe in all respects as with a Davis qua∣drant, till looking through the small hole of the horizon sight, you see the crosse bar and button, in the turning sight, cut the horizon: and at the same instant the sha∣dow of the edge or middle of the object or shadow sight, fall on the middle of the turning sight, by sliding the horizon sight higher or lower, then the middle stroke of the horizon sight, shall cut on the move∣able leg, the suns true altitude required. As f〈…〉〈…〉t stay at 50 degrees, then is the sun 50 degrees above the horizon.