372 Proceedings of the Royal Society 
tional part from 100,000 to 108,000 printed in Hutton, gave rise 
to the idea of carrying the table onwards even so far as to one 
million. Although the bulk of such a table appears to be an 
objection, and the turning of so many leaves a toil, the ease to the 
habitual computer of finding at once the number of which he is in 
search is so great as far to outweigh the opposite considerations. 
Thus, though working only to five places, we prefer to use the 
extensive seven-place tables rather than to take up Lalande’s 
small volume; and so, while working to seven places, we should 
gladly avail ourselves of a nine-place million table, the construction 
of which I proposed to myself, notwithstanding the vast amount of 
the labour. 
The first idea was to interpolate from tables already published, 
but this was opposed by the feeling of dependency on the accuracy 
of the previous calculations. On examining the sources of our 
information on denary logarithms, it became apparent that the 
original work of Henry Briggs (1620), carried on in the laborious 
way indicated to him by John Nepair in his u Constructio,” is the 
only foundation ; and that the completion of the canon by Adrian 
Ylacq (1628) was the last of the original labour that has been 
bestowed on this matter so essential to the progress of exact 
knowledge. 
The more convenient methods of calculation developed by the 
progress of logistics have come, as it were, too late to be of service. 
It is indeed surprising that, after the lapse of two hundred and fifty 
years, we are still relying on the unchecked calculations of Briggs 
and Ylacq; that among so many generations of scientific men 
there has not been zeal enough to effect a revision of the canon. 
Even on the supposition that Vlacq’s logarithms are true in the 
last place, the attempt to interpolate between them would lead to 
frequent uncertainty in the seventh place. In order to form an 
extensive table of seven-place logarithms true in the last figure, we 
should have to carry our original computations at least five steps 
farther. 
Thus I came to perceive the necessity of making the whole 
computation anew. From time to time I took up the work to lay 
it down in alarm at its magnitude, for years of labour only seemed 
to make a beginning ; but about 1849 I happened to obtain a copy 
