Volume 1

The sector on a quadrant, or, a treatise containing the description and use of four several quadrants; two small ones and two great ones, each rendred many wayes, both general and particular. Each of them accomodated for dyalling; for the resolving of all proportions instrumentally; and for the ready finding the hour and azimuth universally in the equal limbe. Of great use to seamen and practioners in the mathematicks / Written by John Collins accountant philomath. Also an appendix touching reflected dyalling [by J. Lyon] From a glass placed at any reclination.

  • Collins, John, 1625-1683.
Date:
1659
Catalogue details

Licence: Public Domain Mark

Credit: The sector on a quadrant, or, a treatise containing the description and use of four several quadrants; two small ones and two great ones, each rendred many wayes, both general and particular. Each of them accomodated for dyalling; for the resolving of all proportions instrumentally; and for the ready finding the hour and azimuth universally in the equal limbe. Of great use to seamen and practioners in the mathematicks / Written by John Collins accountant philomath. Also an appendix touching reflected dyalling [by J. Lyon] From a glass placed at any reclination. Source: Wellcome Collection.

    18/412
    A MOfc ijnincdiAte acccttttl of fhefe ^r6]eBions, ..'H* ■' ' HIrhcrto wc have accommodated our Difeourfe, to (hew how thefe Projections are derived from St$jlers Aftrolabc^and from the Horizontal Projection, of which neither Stefler fas to my knowledge) for I have only feen his 8 Book) nor the learned M. Oughtred^ give no pecu¬ liar Demonftration, as being particular examples of a general cafe, largely (as fuch) infilled on; and this wc have done for the accommodation of Inftrumcnt makers, to whom this Derivation may feem raoft fuitablc; whereas fuch a deduCi’on is not at all neceilary to the Demonftration of the Projections foderived^ . For in the Projection dcr ved from the inverfion of Shfier^ let the eye be fuppofed to be placed in the North Pole, projecting upon the Plain of the EquinoCtialjfuch Circles in the Sphere, as are deferibed in the Quadrant between the twoTropicks, quarter of which Proje^^i- on will be the lame with that on the Q^tacTranCy namely, one of thofe quarters between the South part of the Me¬ ridian and hour of fix, which will leave out all the out¬ ward part of the Almicantcrs between it and the Tropick of Ca}7cer> and in Head thereof* there is takcain fuch a like part of the deprefled Parallels to the Horizon be¬ tween the fame Hour of lix,^ and Tropick of Cafricorn^ ' which is the reverted tail; for the Parallels of Depreflion have the fame rcfpeCltoihc Tropick of Capricerff^ that the Parallels of Altitude have to the Tropick of and will work the fame in clFcCl. In like manner* the Eye in the other Projection may be