Great question. The research I did show's that the ball size and weight has not changed since the late 1800's. I found this information on the following website www.npl.uiuc.edu/~a-nathan/pob/evolution.html. I hope it helps and enjoy. Charles
In 1854 the weight of a Baseball could be between 5 1/2 to 6 1/2 ounces. The size of the ball was 2 3/4 to 3 1/2 inches in diameter. This would make the circumference of the ball to be between 8 5/8 to 11 inches. In 1872 the weight of the ball was changed to be not less than 5 ounces and not more than 5 1/4 ounces. The size was also change to not less than 9 inches to not more than 9 1/4 inches in circumference. This would make the diameter of the ball to be between 2 7/8 to 2 15/16 inches. This is still the size of the ball being used today.
9"- 5 oz."Lemon Peal" Baseballs were one of the first style of baseball used. ten inches in circumference and weighing 5.25 ounces these baseballs were commonly used between 1850 -1860. In 1859 the rules stated that a ball must weigh 5.75 to 6 ounces and measure 9.75 to 10 inches in circumference. Two years later, the ball specifications were changed to 5.5 to 5.75 ounces and 9.5 to 9.75 inches in circumference. By the 1870's the "Figure 8" stitched baseballs were used similar to the baseball used today. The official size and weight of today's baseball is 9" circumference - 5 oz. the same as it was in the 1950's. -Steven KeyManChat with our AI personalities
A regulation sized baseball used by MLB is 5 to 5 1/4 ounces in weight and 9 to 9 1/4 inches in circumference.