He was also responsible for several technical innovations of Morse's system, particularly the first sending key, which Vail invented,[2] and improved recording registers and relay magnets.

Vail was born in Morristown, New Jersey, where his father was an entrepreneur and industrialist who built the Speedwell Ironworks into one of the most innovative iron works of its time.

He enrolled in New York University to study theology in 1832, where he was an active and successful student and a member of the Eucleian Society, graduating in 1836.

[1] Visiting his alma mater on September 2, 1837, Vail happened to witness one of Samuel Morse's early telegraph experiments.

After having secured his father's financial backing, and being a skilled machinist, Vail refined Morse's crude prototype telegraph to make it suitable for public demonstration and commercial operation.

The first successful completion of a transmission with this system was at the Speedwell Iron Works on January 6, 1838, across two miles (3 km) of wire.

Over the next few months Morse and Vail demonstrated the telegraph to Philadelphia's Franklin Institute, members of Congress, and President Martin Van Buren and his cabinet.

Vail retired from the telegraph operations in 1848 and moved back to Morristown, where he spent his last ten years researching genealogy.