This pH meter was made in 1946 by Cambridge Scientific Instrument Co. Ltd. in London. The company was founded in 1881 and the owner eventually became Horace Darwin, the youngest son of the famous scientist Charles Darwin. It is a portable version that can be used on-site in many different situations. A similar instrument was used by the Chemistry Department of what is now the University of Cambridge. The science of pH measurement began in the 1910s and was further developed in 1926. The pH meter is an electronic scientific instrument used to determine the pH measurements of a solution accurately; the amount of acid and alkaline in it This measurement can have many other applications helping to maintain the appropriate balance for a particular result. For example, it can measure the pH of pharmaceutical medications, soil, swimming pool water and hair shampoos. This Cambridge portable electronic pH instrument was made in 1946 by a company specialising in scientific instruments. It is an early example of much smaller devices used today in many different fields including medicine, and the preservation and conservation of shipwreck artefacts. Flagstaff Hill Maritime Museum and Village's Curator uses a pH meter today in the conservation process of a historic cannon that was recovered from the 1839 wreck of the vessel 'Children'.Scientific instrument, electric Cambridge Portable pH Meter in a polished wooden box with compartments, fold-out doors, and leather carry handle. Includes blue covered Instruction manual with a 'Certificate of Test' inside, and chemicals. Electrodes mounted in compartment. The lid is separate from the base, attached by pins and hinges. A plate inside the lid gives instructions for 'Preparation for Use'. Made by the Cambridge Instrument Company, London, in 1946.Printed on plate: "Cambridge Instrument Co. Ltd, 13 Grosvenor Place, London, S.W.1' Certificate dated: "6-3- 46" (1946)flagstaff hill, warrnambool, maritime museum, maritime village, great ocean road, shipwreck coast, ph meter, cambridge scientific instrument co. ltd, horace darwin, cambridge university, ph balance, scientific instrument, ph measurement