1851 Great Exhibition: Official Catalogue: Class X.: Chadburn Brothers
259. CHADBURN BROTHERS, Sheffield and Liverpool — Manufacturers.
Specimens of glass in the rough state, suitable for spectacles.
Glass, cut round and oval, ready for cementing on the blocks.
A block of glasses ready for grinding, being plane or parallel.
A block of glasses ground to the required radius. The focus of the glass depending on the radius of the lap in which they are ground.
A lap, 12 inches radius; glasses when ground on both sides in it, are 12 inches focus.
A block of glasses, ground and polished, ready to be taken off.
Tool used for polishing the glasses.
A block of concave glasses finished; being cemented in the lap, they are ground hollow.
Glasses ready for fitting into spectacles. The exhibitors grind 750 dozen per week, on the average.
Provisionally registered portable barometer. The improvement consists in making the cistern of glass (which is covered) with a flexible cover, which can be pressed down, so as to prevent the mercury oscillating when the barometer is carried about or packed for travelling.
Optical lenses, of various kinds.
Spectacles—reading and magnifying glasses, etc.
Opera glasses and small telescopes.
Day or night ship and signal telescopes.
Large and portable achromatic telescopes.
Simple and compound microscopes.
Magic lanterns and views.
Camera-obscuras and diagonal mirrors.
Agricultural and surveyors' levels, etc.
Horse-shoe and other magnets.
Steam and vacuum gauges.
Barometers, etc.
Garden and window syringes.
Galvano-electric machines.
Ship's berth or side illuminators and ventilators.
Working models of steam-engines, etc.
Craig's charactograph.