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Proceedings of the Royal Society 
he gives an eight-place table of logarithms arranged in the compact 
manner now usually adopted. In the address to the reader, he 
speaks contemptuously of Adrian as “ Ylaq the Dutchman,” 11 from 
whose corrupt and imperfect copy,” &c. ; and in the introduction he 
describes a mode of computing logarithms which the innocent 
reader may believe to have been followed by the author of the 
book, but a collation shows that Ylacq’s misprints have been 
slavishly copied by the indignant Newton. 
It was not until 1794 that anything claiming to be a revision of 
the original table appeared ; this was the ten-place table given by 
G-eorg Yega in his “ Thesaurus Logarithmorum,” the arrangement 
being after the compact manner introduced by Newton. Yega 
gives a long list of corrections on Ylacq’s table, which by that 
time had become scarce, and it was generally understood that he 
had at least taken the precaution of adding up Ylacq’s differences 
in order to eliminate the misprints. But on collating the list of 
errors which I have just discovered in Ylacq, with Yega’s table, 
we are forced, however reluctantly, to the conclusion that Ylacq’s 
identical table had been used by the compositor of Yega’s pages. 
A review of the character of the errors will make this clear ; a list 
of them is subjoined, showing the logarithms true to fifteen places 
(the first five being omitted), the last group as it should have been 
in Ylacq, Ylacq’s corresponding five, and Yega’s last group of three. 
Of the forty-two errors shown in Ylacq, forty are last-place 
errors, such as we are considering; and two, marked with asterisks, 
are misprints, as is known by the circumstance that the adjoining 
differences are correct. As was to have been expected, all the 
final errors are copied by Yega, who never pretended to have made 
a new computation ; of the misprints one, a 9 for a 6, is 
corrected; but the other, 646 instead of 626, is retained. Not 
only so, among the final errors there are six belonging to numbers 
ending in 0 ; now these logarithms occur in the preceding part of 
the table, where they are correctly given, and yet these also, of 
easy detection, are retained by Yega. Thus, again, Yega is only 
Ylacq in a new and much more convenient form. 
The only work claiming to be an original computation of 
logarithms is that done in the Bureau du Cadastre, at the instance 
of the French Government. This unpublished work contains to 
