Thomas A.Watson was his assistant, and both Bell and Watson lived nearby, in two cheap little bedrooms.

The rent of the workshop and bedrooms, and Watson's wages of nine dollars a week, were being paid by Sanders and Hubbard.
Consequently, when Bell returned from Washington, he was compelled by his agreement to devote himself mainly to the musical telegraph, although his heart was now with the telephone.

For exactly three months after his interview with Professor Henry, he continued to plod ahead, along both lines, until, on that memorable hot afternoon in June, 1875, the full TWANG of the clock-spring came over the wire, and the telephone was born.
From this moment, Bell was a man of one purpose.

He won over Sanders and Hubbard.

He converted Watson into an enthusiast.