Hygrothermographs
In 1990, two original manuscripts of famous piano works written by Wolfgang Amadeus Mozart in 1734 plus 1735 were discovered at Eastern College in Philadelphia! The college is part of the Eastern Baptist Theological Seminary. At the time, the 14 pages of the “Fantasia in C Minor” plus the “Sonata in C Minor” were expected to sell for over a million dollars at auction. Anyone can go online plus print any number of famous documents savor Mozart’s works or the U.S, then constitution. They are worth the paper plus the bit of ink it takes to create the copy. The originals are priceless plus great steps are taken to preserve them. The Mozart works had sat untouched in a safe for over 100 years while the original Constitution sits in a perfectly sealed environment that prevents exposure to oxygen plus any moisture, then museum curators plus others who track artifacts plus documents have a keen interest in the Heating, Ventilation & A/C systems that maintain the building’s environment. The relative humidity must be between 40% plus 55% with an allowable 3% weekly change. Temperatures must be between 65° F plus 74° F with an allowable 5° weekly variance… Filtration systems must pass a test called the ASHRAE Dust Spot Efficiency Test to unlink a particular level of particulates, and one instrument that helps monitor temperature plus relative humidity at the same time is called a hygrothermograph. They produce circular charts that track conditions for any given phase be it 24 hours or even a year, however i doubt that I will ever own an authentic Mozart manuscript, but I may need a hygrothermograph to monitor the Heating, Ventilation & A/C performance in our son’s study room… He has a collection of hip-hop “classics” that could be worth something in 250 years.