6
Fact 1
Privileged with knowledge of the Latin language, Vlacq gets acquainted with
Briggs' Arithmetica Logarithmica at the age of 25; he is not so sure about his own
mathematical abilities, and consults some mathematicians or arithmeticians,
including De Decker, on the potential usefulness of a fully completed "Great
Table". His business instinct tells him that publishing a table for the European
continent, in a living language like French or Dutch, with a full range of numbers
of 1 to 100,000 - without a gap - and swiftly executed by suppressing some
precision from Briggs' 14 decimals in the calculations, could be a worthwile and
profitable investment. His conscience does not trouble him with possible
plagiarism because, in his introduction to [3], Briggs has actually invited others to
execute the calculations to resolve the gap in his Arithmetica Logarithmica. But
Vlacq did not inform Briggs of his plan (which Briggs also had asked in his
invitation); in the preface to his own publication [6], he describes in detail the
above-mentioned motives for his approach, adding the altruistic remark this would
ensure "sufficient copies to be available for this country, and also in an other
language than Latin".
Facts 2, 3 and 4
Vlacq's business sense also makes him legally contract partners for the project,
and obtain copyright ("Privilegie") from the authorities ("Staten Generaal") to
publish the "Great Table", for 10 years.
What May Actually Have Happened: Fact and Fiction
When we try to image the full story of Vlacq and De Decker, we might agree on
the following scenario, which agrees with the facts above.
The surprising aspect of fact 7 is that the one known copy of Tweede dee! van de
Nieuwe Teikonst was discovered only in 1920, see [22]. This means that before
1920 all research on early tables was based on incomplete information, resulting
today in a state of confusion: some people claim that De Decker was literally the
first to print a complete logarithmic "Great Table" of 1 to 100,000, because of fact
7. Others, having used research results from before 1920, still believe Vlacq was
the first. And then we have the majority who give credit for the "Great Table" to
both Dutchmen equally, given the compelling argument:
Without either of the two, the "Great Table" would not have materialised in
Gouda. Vlacq provided the first initiative, his business sense, translation of
Briggs' texts from Latin, some part of the calculations, the new
trigonometrical tables and the successful academic 1628 edition [6] of the
"Great Table" as part II of Briggs' work, while De Decker did the major part
of the calculations and finalised the "Great Table" proper, although his
commerce-oriented 1627 edition [5] did not reach the public.
