The letterhead is from:
"United States Land Office
W. C. Child, Register.
Sol Star, Receiver."
Dated July 19 1873. The letter reads:
"Thos B Gray
In Montanian of July 17th you will find a 'notice to miners' application of Charles Hapgood to enter the NE4 [northeast quarter] of SE4 & SE4 of NE4 Dec 14 [? 3S 1W]. Hearing as to character of said land before Isdell[?] Aug 16/73. At which place you will appear & put in your protest [&?] give such testimony as will be necessary to show the mineral character
Perhaps a farmer has claimed the land that Mr. Gray already has a mining claim for.