- “The size of the baseball was standardized back in the 1860s. It was to weigh between 5 and 5.25 ounces, with a circumference between 9 and 9.25 inches. It was manufactured by winding yarn around a small core of cork, rubber, or similar material, then encasing the sphere in horsehide stained white with slightly raised red stitches.” Clearing the Bases (Schmidt, Mike;Waggoner, Glen) Kindle Location 1769-1771 (Clearing the Bases, Baseball)