Hangings had usually been carried out by untrained county sheriffs, but when electrocution was introduced in New York, the first in the world ever to adopt it, it was felt that a trained electrician should be hired to operate the chair.
Davis also held patents on certain features of the electric chair and trained two of his successors, Robert G. Elliott and John Hulbert, who served as his assistants during executions.
Since Sing Sing became the only prison in the state to house a death row and execution chamber, about a week before an electrocution was scheduled to be carried out, the warden would send a letter to the state electrician to notify him.
State electrician Robert G. Elliott, who executed nearly 400 inmates in six states, including New York, developed an electrocution technique that came to be known as the "Elliott method" and was subsequently used by all of his successors in Sing Sing.
[3] In brackets is the time period during which each state electrician, when his name is known, actively performed executions.