606 MISCELLANEOUS PAPERS. 



licioiis persons. Under such conditions every etalou would sooner or 

 later become too long and require sliorteuing. 



Respecting the ancient toise of the masons there are two contradict, 

 ory stories. On December 1, 1714, La Hire showed to the French 

 Academy what he characterized as "a very ancient instrument of 

 mathematics, which has been made by one of our most accomplished 

 workmen with very great care, where the foot is marked, and which has 

 served to reestablish the toise of the Ohatelet, as I have been informed 

 by our old mathematicians."* Forty-four years later, on July 29, 1758, 

 La Condamiue stated to the Academy that " We know only by tradition 

 that to adjust the length of the new standard, the width of the arcade 

 or interior gate of the grand pavilion, which served as an entrance 

 to the old Louvre, on the side of the rue Fromenteau, was used. This 

 opening, according to the plan, should have been twelve feet wide. Half 

 of it was taken to fix the length of the new toise, which thus became 

 five lines shorter than the old one."t Of these two contradictory state- 

 ments that of La Hire seems altogether most trustworthy, and the 

 ordinary rules of evidence indicate that it should be accepted to the 

 exclusion of the other. 



In 1(508 the etalon of the new toise,.since known as the toise-etalon 

 du Chdtelet, was fixed against the wall at the foot of the staircase of 

 the grand Chatelet de Paris, by whom or at what season of the year 

 is not known. Strange as it now seems, this standard (very roughly 

 made, exposed in a public place for use or abuse by everybody, 

 liable to rust, and certain to be falsified by constant wear) was actually 

 used for adjusting the toise of Picard, that of Cassini, the toise of Peru 

 and of the North, that of La Caille, that of Mairan — in short, all the 

 toises employed by the French in their geodetic operations during the 

 seventeenth and eighteenth centuries. The lack of any other recog- 

 nized standard made the use of this one imperative; but the French 

 academicians were well aware of its defects and took precautions to 

 guard against them. 



The first toise copied from the etalon of the Chatelet for scientific 

 purposes was that used by Picard in his measurement of a degree of 

 the meridian between Paris and Amiens. | It was made about the 

 year 1668, and would doubtless have become the scientific standard of 

 France had it not unfortunately disappeared before the degree measure- 

 ments of the eighteenth century were begun. The second toise copied 

 from the etalon of the Chatelet for scientific purposes was that used by 

 Messrs. Godin, Bouguer, and La Condamiue for measuring the base of 

 their arc of the meridian in Peru. This toise, since known as the toise 

 du Perou, was made by the artist Langlois under the immediate direc- 

 tion of Godin in 1735, and is still preserved at the Paris Observatory.§ 

 It is a rectangular bar of polished wrought iron, having a breadth of 

 1.58 English inches and a thickness of 0,30 of an inch. All the other 



* 2, p. 395. 1 17, p. 484. t fi, Art. 4, p. 15. ^ 17 p. 487, and 53, p. C. 2. 



