of Edinburgh , Session 1874 - 75 . 425 
read to the Academy on the 25th May 1857, and entitled “ Note 
snr les erreurs que contient une des Tables de Logarithmes de 
Callet, par M. F. Lefort,” shows its author to possess every claim 
to our confidence and respect as a computer. The indication of 
wholesale errors in Callet’s twenty-place table (copied also into 
Hutton’s) is invaluable, as preventing farther mistake, and as 
showing the absolute need for a revision of our most trusted tables. 
The second paper is in vol. xlvi., and was occasioned by remarks 
on the presentation to the Library of the Institute of a manuscript 
copy of the great tables which had been in the possession of Prony 
himself. It was presented by Prony’s heirs, at the meeting of the 
Academy, on Monday the 17th May 1858. 
In the course of remarks after the presentation, M. Elie de 
Beaumont expressed his opinion that the best means of preserving 
the work would be to print it ; and M. Leverrier, drawing attention 
to M. Lefort’s labours, spoke as if a doubt exist even as to the 
whereabouts of the veritable original calculations. 
At the next meeting, that of the 24th May 1858, the note above men- 
tioned was read, entitled, ‘‘Note sur les deux exemplaires manuscrits 
des G-randes Tables logarithmiques et trigonometriques, calculees au 
Bureau du Cadastre, sous la direction de Prony ; par M. F. Lefort.” 
I regret that the length of this most remarkable and most 
valuable memoir precludes its reproduction here. As, however, 
the “ Comptes Rendu s” are very widely distributed, a verification 
of my remarks upon it is within the reach of many. The note 
refers almost exclusively to the logarithmic part of the tables. 
It tells us that the great work was accomplished by a staff of 
computors, divided into three sections ; the first section consist- 
ing of four or five geometers, whose business was to do the purely 
analytical part, and to calculate certain fundamental numbers ; the 
second section was formed of seven or eight calculators acquainted 
with analysis : they made calculations directly from the formulae 
arranged by the first section. The third section contained seventy 
to eighty persons having a very slight acquaintance with mathe- 
matics, whose business was to perform the additions and subtrac- 
tions prescribed by the second section. 
We have here a little army, with its generals and lieutenants, 
M. Prony himself being commander-in-chief. Lefort does not 
