A Victorian lacquered brass compound monocular field microscope Unsigned, circa 1870 The tube with moulded collar and rack-and pinion focus adjustment sliding within a sleeve decoratively pierced to form twin supports, enclosing stage with slide apertures to each side and incorporating helical retention spring, on moulded ring base, in original mahogany box with six objective lenses, forceps, tweezers and other accessories including six prepared bone sliders, (lacking eyepiece and mirror), the box 27cm (10.5ins) wide; with a cased glass set of hydrometers, Negretti and Zambra, London, late 19th century, comprising eleven blown glass floats each with mercury filled bulb beneath ovoid air chamber and cylindrical stem enclosing a calibrated ivorine scale inscribed TEMP 60 and signed NEGRETTI & ZAMBRA LONDON to verso, in original velvet and silk lined fitted mahogany box with a Fahrenheit scale mercury-tube thermometer and a test-tube, the box 27.5cm (10.75ins) wide (2). The hydrometers in the current lot are by Negretti & Zambra who are recorded in Banfield, Edwin BAROMETER MAKERS AND RETAILERS 1660-1900 as being established in 1850 when a partnership between Enrico Negretti and Joseph Warren Zambra was formed. The firm became one of the most prolific makers of scientific instruments and continued trading well into the 20th century.