The Biblioteca Barbarini of Rome possesses four armillary spheres, all appearing to be of the early seventeenth century. A description of two of these, neither signed nor dated, it has not been possible to obtain; two are the work of J. Paolo Ferreri, the one constructed in the year 1602 according to the brief record “Jo. Paulus Ferrerius f. f. an. 1602,” and the other in the year 1624 being inscribed “Fᵉᵒ gio. Paulo Ferreri Roⁿᵒ** ano 1624.” Professor Uzielli has given to the author the information that these are of brass, having each a graduated horizon circle supported by four half circles which in turn rest on a single brass column. Through this horizon circle passes an adjustable meridian circle 39 cm. in diameter, which is graduated and which supports other movable circles, such as the colures carrying the polar circles, the tropics, which are graduated, and the ecliptic, a broad band inclined 23-1/2 degrees to the equator, likewise graduated and engraved with the names of the months and of the constellations of the zodiac. Within the circles of each of these spheres, placed at what may be called their common center, is a small solid sphere to serve as a representation of a terrestrial globe but without geographical details. There appear to be but slight differences in the construction of these two armillary spheres, the one of 1624 having certain circles which are slightly smaller than are the corresponding ones on that of earlier date. From the same source it is learned that the artist, Tito Lessi of Florence, possesses an armillary sphere signed and dated “Lud: ˢ Sem: ˢ Bon: Fac: A. D. MDCXII,” near which is a representation of a coat of arms with a dragon. The sphere is of brass, the diameter of its greatest circle being 63 cm. We know nothing of the Ludovico referred to as the maker, but who, as is noted, was a Bolognese. The same artist, as we are informed, likewise possesses another unsigned and undated armillary sphere which presumably is of the early seventeenth century.