On the History of Gunter's Scale and the Slide Rule During the Seventeenth CenturyCajori, Florian
History
On the History of Gunter's Scale and the Slide Rule During the Seventeenth Century
Cajori, Florian
Slide-rule
Hence from the forme, I have called it a Ring, and Grammelogia by
annoligie of a Lineary speech; which Ring, if it were projected in the
convex unto two yards Diameter, or thereabouts, and the line Decupled, it
would worke Trigonometrie unto seconds, and give proportionall numbers
unto six places only by an ocular inspection, which would compendiate
Astronomicall calculations, and be sufficient for the Prosthaphaeresis of
the Motions: But of this as God shall give life and ability to health and
time.
The unnumbered page following page 22 contains the patent and copyright on
the instrument and book:
Whereas Richard Delamain, Teacher of Mathematicks, hath presented vnto Vs
an Instrument called Grammelogia, or The Mathematicall Ring, together
with a Booke so intituled, expressing the use thereof, being his owne
Invention; we of our Gracious and Princely favour have granted unto the
said Richard Delamain and his Assignes, Privilege, Licence, and
Authority, for the sole Making, Printing and Selling of the said
Instrument and Booke: straightly forbidding any other to Make, Imprint,
or Sell, or cause to be Made, or Imprinted, or Sold, the said Instrument
or Booke within any our Dominions, during the space of ten yeares next
ensuing the date hereof, upon paine of Our high displeasure. Given under
our hand and Signet at our Palace of Westminster, the fourth day of
January, in the sixth yeare of our Raigne.
Delamain’s later designs, and directions for using his instruments
In the Appendix of Grammelogia III, on page 52 is given a description of an
instrument promised near the end of Grammelogia I:
That which I have formerly delivered hath been onely upon one of the
Circles of my Ring, simply concerning Arithmeticall Proportions, I will
by way of Conclusion touch upon some uses of the Circles, of Logarithmall
Sines, and Tangents, which are placed on the edge of both the moveable
and fixed Circles of the Ring in respect of Geometricall Proportions, but
first of the description of these Circles.
First, upon the side that the Circle of Numbers is one, are graduated on
the edge of the moveable, and also on the edge of the fixed the
Logarithmall Sines, for if you bring 1. in the moveable amongst the
Numbers to 1. in the fixed, you may on the other edge of the moveable and
fixed see the sines noted thus 90. 90. 80. 80. 70. 70. 60. 60. &c. unto
6.6. and each degree subdivided, and then over the former divisions and
figures 90. 90. 80. 80. 70. 70. &c. you have the other degrees, viz. 5.
4. 3. 2. 1. each of those divided by small points.
Secondly, (if the Ring is great) neere the outward edge of this side of
the fixed against the Numbers, are the usuall divisions of a Circle, and
the points of the Compasse: serving for observation in Astronomy, or
Geometry, and the sights belonging to those divisions, may be placed on
the moveable Circle.
Public-domain text, read in full here on John Shaqi.
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