It is worthy of note that Coggeshall’s slide rule book, The Art of
Practical Measuring, was reviewed in the Acta eruditorum, anno 1691, p.
473; hence Leupold’s description[37] of the rectilinear slide rule in his
Theatrum arithmetico-geometricum, Leipzig, 1727, Cap. XIII, p. 71, is not
the earliest reference to the rectilinear rule found in German
publications. The above date is earlier even than Biler’s reference to a
circular slide rule in his Descriptio instrumenti mathematici universalis
of 1696.
Two noted slide rules for gauging were described by Tho. Everard,
Philomath, in his Stereometry made easie, London, 1684. He designates his
lines by the capital letters A, B, C, D, E. On the first instrument, A on
the rule, and B and C on the slide, have each two radiuses of numbers, D
has only one, while E has three. The second rule is described in an
Appendix; it is one foot long, with two slides enabling the rule to be
extended to 3 feet.
Everard’s instruments were made in London by Isaac Carver who, soon after,
himself wrote a sixteen-page Description and Use of a New Sliding Rule,
projected from the Tables in the Gauger’s Magazine, London, 1687, which was
“printed for William Hunt” and bound in one volume with a book by Hunt,
called The Gauger’s Magazine, London, 1687. This appears to be the same
William Hunt who later brought out descriptions of his own of slide rules.
The instrument described by Carver “consists of three pieces, two whereof
are moveable to be drawn out till the whole be 36 inches long.” It has
several non-logarithmic graduations, together with logarithmic lines marked
A, B, C, D, of which A, B, C are “double lines,” and D a “single line” used
for squares and square roots. It is designed for the determination of the
vacuity of a “spheroidal cask lying,” a “spheroidal cask standing,” and a
“parabolical cask lying.”
Another seventeenth century writer on the slide rule is John Atkinson, whom
we have mentioned earlier. He says:[38] “The Lines of Numbers, Sines and
Tangents, are set double, that is, one on each side, as the middle piece
slides: which middle piece is so contrived, to slip to and fro easily, to
slide out, and to be put in any side uppermost, in order to bring those
Lines together (or against one another) most proper for solving the
Question, wrought by Sliding-Gunter.”
The data presented in this article show that, while the earliest slide
rules were of the circular type, the later slide rules of the seventeenth
century were of the rectilinear type.[39]
January 12, 1915.