With the coin now in production, Barber monitored the rate at which dies were expended, as it was the responsibility of his Engraver's Department to supply all three mints with working dies. On March 11, 1913, he wrote to Landis that the dies were being used up three times faster than with the Liberty Head nickel. His department was straining to produce enough new dies to meet production. In addition, the date and denomination were the points on the coin most subject to wear, and Landis feared the value on the coin would be worn away. Barber made proposed revisions, which Fraser approved after being sent samples. These changes enlarged the legend "FIVE CENTS" and changed the ground on which the bison stands from a hill to flat ground. According to data compiled by numismatic historian David Lange from the National Archives, the changes to what are known as Type II nickels (with the originals Type I) actually decreased the die life. The new Treasury Secretary, William G. McAdoo, wanted further changes in the coin, but Fraser had moved on to other projects and was uninterested in revisiting the nickel. The thickness of the numerals in the date was gradually increased, making them more durable; however the problem was never addressed with complete success, and even many later-date Buffalo nickels have the date worn away.