A set of six blown glass Geissler tubes Unsigned, late 19th century Each of differing complex shaped tube design with loop terminals and spike electrodes within swollen chambers to each end, each 15cm (6ins) long, in original cardboard box; with a cold-cathode ion X-ray tube by Cuthbert Andrews, London, early 20th century, printed with indistinct trade label and numbered 113171 to the sphere, mounted on wooden stand secured by leather straps, 38cm (15ins) long; and a modern cathode-ray deflection tube, unsigned, 65cm (25.ins) long, (3). Geissler tubes were devised by the German physicist and glassblower Heinrich Geissler in 1857 as an early form of gas discharge demonstration apparatus designed to demonstrate the principles of electrical glow discharge. The X-ray tube was made by Cuthbert Andrews (1882-1972) who Andrews teamed up with C H F Müller, a German x-ray tube maker, to produce X-ray tubes from 1912. During the 1930's Andrews' company became the sole British makers of x-ray tubes and once World War II broke out an alternative manufacturing site was established outside London.