Adam Field wrote: > Is the two wire method assuming the reference wire is at the outside > air ambient temperature? Otherwise, you have two unknowns cooling the > wire, the air flow rate and the temperature (and pressure) of that > air. You can look up "hot wire anemometer". These are existing devices but know= n to not be too accurate. For example, typhoon Paka in the Pacific in 1997 was first thought to have beat the previous land wind speed record of 231 miles/hour on Mt Washington in 1934. The Paka measurement was made with a hot wire anemometer, and was later determined not to have reliably indicate= d a record breaking speed. ******************************************************************** Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products (978) 742-9014. Gold level PIC consultants since 2000. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .