Preheat the oven to 400`F.

In a large bowl, mix together the sugar, butter, shortening and eggs in large bowl.

Once they're well combined, stir in flour, cream of tartar, baking soda and salt.

Pinch off about a rounded teaspoon of dough at a time, and roll them into balls.

Mix together the 1/4 cup sugar and the cinnamon for rolling. Roll the balls in the cinnamon-sugar mixture until the outside is coated with a layer of cinnamon and sugar.

Place the cookie balls about 2 inches apart on an ungreased cookie sheet.

Bake the cookies for about 8 to 10 minutes.

Let the cookies cool for a couple minutes on the cookie sheet, then move them carefully to a cooling rack to finish cooling.