Microscope Museum

Collection of antique microscopes and other scientific instruments

Microscope 560 (Casartelli; folding linen tester; late 19^th century to the early 20^th century)

Guiseppe Luigi Casartelli (1823 – 1900) emigrated as a child from Italy to Liverpool, England, joining a relative’s scientific instrument firm business. He changed his name to Joseph Louis Casartelli and later moved to Manchester where he established himself as a manufacturer of optical equipment, trading at 43 Market Street for many years. Around 1850, Casartelli produced microscopes, telescopes and other optical devices. By the 1870s-80s, Casartelli’s business focussed on supplying the heavy industries of Manchester, including fittings for steam engines, mining equipment and optical instruments for the fabric industry. One of Casartelli’s sons, Joseph Henry, was made a partner of the company and the business became “J. Casartelli and Son” in 1896. Casartelli’s business moved to 18 Brown Street, Manchester in 1922, acquired the business of another family member in Liverpool in 1929, but was liquidated during the Great Depression in 1933. Parts of the business continued under different ownerships, including the Liverpool business as ‘J. Casartelli & Son (Liverpool)’ (later ‘Casartelli Instruments Ltd.’, in 1984, which closed in 1989), and the original business became ‘J. Casartelli & Son Ltd.’ (and then ‘John Casartelli (M/c) Ltd.’ in 1939). Microscope 560 is a folding linen tester, or linen prover, engraved with “6 MILL, Casartelli, Manchester”. The instrument should be dated from the late 19th century to the early 20th century and would be used for counting threads in fabrics (the number of threads per unit of length provides evidence of a higher quality of cloth). These instruments fold flat for storing and transport and form a 'C' shape when in use. The earliest forms have a simple standard opening on the base, but later versions have this opening marked with calibrations of some kind. These types of linen testers have been made and sold by many companies since at least the early 19th century and were rarely signed by their makers or retailers (Figure 1).

Figure 1. Folding linen testers engraved in the catalogues of several companies: (A) Palmer (1840); (B) Negretti and Zambra (1859); (C, D) William McAllister (1867); (E, F) Negretti and Zambra (1870s e 1885); (G) James Queen (1870 and 1872); (H) Ernest Goldbacher (1879); (I) B. Kahn & Son (c. 1890); (J) Bausch and Lomb (1892); (K) Arthur Thomas (1914); (L) Bausch and Lomb (1914); (M) A. Clarkson & Co (1920s); (N) Emille Deyrolle (1931); and (O, P, Q) Gallenkamp (c. 1939)