of Edinburgh, Session 1874-75. 581 
have been extended to 14 figures for the first ten thousand num- 
bers, whose logarithms had been computed to 19 places at the 
Bureau du Cadastre.” All the mystery lies here. MM. Letellier 
et Gruy^tant were not calculators of the second section, and they 
confined themselves to the comparison of the work of Briggs with 
that which was done by the computers in the Bureau du Cadastre, 
who, like them, belonged to the third section. 
We know that Legendre has published in his “ Treatise on 
Elliptic Functions ” the logarithms of all prime numbers from 1 to 
10,000, as obtained from the calculations made at the Bureau du 
Cadastre. 
The following errata does not contain the errors printed at page 
xxx. of the Thesaurus Logarithmorum Completus; it is taken for 
granted that the errors pointed out by the author have been already 
corrected on the computer’s copy. 
Eeply to M. Lefort’s Observations. By Edward Sang. 
From M. Lefort’s opening sentence it appears that he had only 
recently received the copy of my remarks which had been posted 
to him on 22d December. Perhaps on this account M. Lefort has 
been hurried in the perusal of my paper, and so has fallen into 
several mistakes as to my meaning. These will be apparent to 
any one who peruses the writings, and I shall pass them over 
entirely, confining myself to the very few points which are essen- 
tial to the subject in hand. The only extraneous matter to which 
I shall allude is this, that while M. Lefort has obviously and justly 
been desirous of upholding the dignity of the Grrandes Tables du 
Cadastre, he has, in the true spirit of an inquirer after truth, 
clearly and faithfully exhibited even those points which press 
most sorely on his own position. 
While disclaiming any intention to enter into the controversy 
opened by “Nature,” he at once plunges into it in support of the 
thesis enunciated by the non nemo of that periodical — “Almost 
all the errors found by Mr Sang by means of this table are among 
those there given by Lefort, and any one who chooses can, without 
much expenditure of trouble, render his copy of Ylacq all but free 
