Born in Wappingers Falls, New York. Married Madgie Van Houton in 1884. They had three sons and a daughter.

He began as a coin dealer in 1873. Under his own name he conducted five auction sales 1876 to 1887. He had a habit of going to the Mint early each January and buying up the stock of unsold proof coins. He joined the dealership of J. W. Scott and cataloged many of their sales 1877 to 1886. In about 1888 he joined a partnership with Harlan P. Smith in the New York Coin and Stamp Company. Smith provided the financing and Proskey wrote the catalogs. When Smith died in 1903 Proskey bought his share. He continued to operate the New York Coin and Stamp Company. The business was continued after his death by his son David V. Proskey.

Editor of the Coin Collector's Journal for 12 years. He wrote a series of articles on large cent varieties for the CCJ. He issued a fixed price list of silver coins in 1878. He died at home in North Caldwell, New Jersey.

In 2017 he was inducted into the PCGS CoinFacts Coin Dealer Hall of Fame.

bio: Adams I obit: NUM 41 Oct 1928 page 616; ANAHist 425’ The E-Sylum 5/3/2021