The most delicious cookie in the world and the easiest (and most fun) to make. The kids love to help! I got the recipe from my mother eons ago, probably when I got married and have been making them ever since.
In a large bowl, mix together the butter, 1 1/2 cups sugar, and the eggs.
In a separate bowl, mix cream of tartar, soda, salt, and flour. Gradually add to first mixture.
Once thoroughly mixed and no more flour is visible, form small balls, about the size of a walnut. Mix the 4 Tbsp. sugar and the cinnamon together in small bowl. Roll the balls in the mixture, careful to cover all sides.
Place the cookie balls on a large cookie sheet about 2" apart. I usually get 20 on each cookie sheet. DO NOT FLATTEN BALLS! They will flatten themselves perfectly. Bake at 375º for 10 minutes.