Thacher's cylindrical slide-rule in fitted mahogany box; base marked "Keuffel & Esser Co. N.Y. 4012 3328"
Loga calculator (cylindrical slide rule) patented by Daemen-Schmid, Zurich Loga calculator (cylindrical slide rule) patented by Daemen-Schmid
"Rouleau" calculator, no.16, with waterproof cover (a cylindrical slide rule) "Rouleau" calculator 1920
