Hygrothermographs
In 1990, two original manuscripts of famous piano works written by Wolfgang Amadeus Mozart in 1784 and 1785 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” and the “Sonata in C Minor” were expected to sell for over a million dollars at auction. Anyone can go online and print any number of famous documents like Mozart’s works or the U.S. Constitution. They are worth the paper and the bit of ink it takes to create the copy. The originals are priceless and 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 and any moisture. Museum curators and others who oversee artifacts and documents have a keen interest in the HVAC systems that maintain the building’s environment. The relative humidity must be between 40% and 55% with an allowable 3% daily fluctuation. Temperatures must be between 65° F and 75° F with an allowable 5° daily variance. Filtration systems must pass a test called the ASHRAE Dust Spot Efficiency Test to remove a certain level of particulates. One instrument that helps monitor temperature and relative humidity at the same time is called a hygrothermograph. They produce circular charts that track conditions for any given period be it 24 hours or even a year. I doubt that I will ever own an authentic Mozart manuscript, but I may need a hygrothermograph to monitor the HVAC performance in my son’s bedroom. He has a collection of hip-hop “classics” that could be worth something in 250 years.