This is essentially the same as Mason's pattern where one thermometer is kept wet by means of a water soaked sock covering one bulb and the other kept dry. The evaporation of water from the sock has the effect of lowering the temperature reading on the wet thermometer and the difference against the dry thermometer is used to calculate relative humidity of the air.Negretti & Zambra were a leading name in the production of meteorological and scientific instruments. Their early affiliation with Admiral Fitzroy and his developments in meteorology and with the RNLI made them a household name within the British Isles. Throughout their long and esteemed history they exhibited at all British and worldwide industrial fairs and became makers to both Queen Victoria and Edward VII and their contributions to scientific development in the second half of the Nineteenth Century cannot be underestimated. They continued to service the general public and the scientific community alike until the late 1960's whereafter they focused solely on the aviation industry in numerous guises until its eventual liquidation in the year 2000. A sad end to a hundred and fifty years of quality manufacturing. This is a somewhat unusual example of its style although the Negretti & Zambra hygrometer appeared in various forms within all their catalogues through the decades of their existence. It should be noted from the images that the wet thermometer scale has a crack across its width where it has been screwed to the backboard. This is a common complaint caused by movement of the wood and the rigidity of the screws over the years. It is, however, stable and remains perfectly secure. Jason Clarke Antiques are happy to discuss carriage, condition or for any other queries, alternatively, you can also message us and we will endeavour to come back to you as soon as possible.
This item is in the category "Antiques\Science/Medicine\Scientific Instruments". The seller is "jason750_1" and is located in this country: GB. This item can be shipped to United Kingdom.