This instrument was made after 1855 when Marc François Secretan went into business on
his own, and before 1901 when the Smithsonian purchased it from Anthony J. Gies,
Commissioner of Streets and Drainage in Manila, for use in the Pan American Exhibition. It is
similar to the instrument that Secretan called a repeating theodolite. The horizontal circle is
silvered, graduated to 10 minutes, and read by four verniers and two magnifiers to 20 seconds;
the vertical circle is silvered, graduated to 15 minutes, and read by two double verniers to 30
L'Industrie Française des Instruments de Précision, Catalogue (Paris, 1901-1902), pp. 247-252.