Notes on the use of propagation of error formulas

Th e " la w of propagation o[ error" is a tool th a t physical sc ienti s ts have co nve nie ntly and fre qu en tly used in th e ir work for ma n y years, yet an adeq uate refere nce is diffi c u lt to find. In thi s paper an expository rev ie w of thi s topi c is prese nte d , partic ularly in the li ght of c urre nt prac ti ces a nd interpretation s. Examp les on t he acc uracy of th e approximations are give n. The reportin g of th e un ce rtainti es of final res ults is di sc ussed .