If it’s from his time as President, it may be secretarial or a stamp or autopen. Presidents stopped signing such documents early in the 19th century or they’d be spending every waking hour signing.
You know you got me wondering now.
It starts out “In testimony whereof, I, Calvin Coolidge Pres of U.S. have caused these letters to be made patent etc.etc. Given under my hand at the city of Washington the first day of August 1924
By the President____his signature
By Viola B Pugh, secretary
M. P. Leroy Recorder of the general land office
I don’t know if that means it was sighed by Viola or if he actually signed it himself. Your probably right he probably never signed himself.
I did a search for his signature and I think she must have signed for him. Oh well, another bursted bubble. I always thought it was his signature.:^)