1) Mix butter, eggs, & sugar together thoroughly.
2) Sift flour, cream of tartar, soda & salt together, add to above mixture.
3) Chill dough 2-3 hours, then roll into balls the size of small walnuts.
4) Roll in cinnamon / sugar mixture.
5) Bake at 400 degrees 8-10 min, on greased cookie sheets.