There are two charts in McFerrin's "The Piano -- Its Acoustics" for Fand C. For wet 50 and dry 70 F it gives 19%. For wet 45 and dry 70 it gives 3%. It goes down to 1 %. (p132) The temp range is from 41 to 80 F. They are readings for the sling type hygrometers with 10 feet per second air speed. It doesn't say anything about stationary wet-dry bulb units. The source is given as "relative humidity tables for use with Taylor Hygrometers. A "leaflet" is mentioned, "What is this thing called Humidity?" Taylor if still in business they might be on the web. No formula was mentioned to obtain the values for the readings. So it looks like it would have to be hand copied into a spread sheet. This book (McFerrin) is still sold by supply houses so is much cheaper to buy spending the time to copy the data into a spread sheet, and besides you get a ton of useful information, like tension formulas, inharmonicity formulas, bass string tension formulas, American, English and Metric wire sizes. If someone has formulas that could be used in a spread sheet I will be glad to set one up complete with input boxes and a record keeping section; as a favor for the CAUT list. ---ric
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