While working on the Rutland & Burlington railroad in Cavendish, Vermont, with his former physics teacher Hosea Doton,[3] he was the first physician to treat railroad contractor Phineas Gage after Gage survived accidentally blasting a tamping iron through his jaw and skull while setting an explosive charge.

There he began practicing medicine with his brother-in-law, Dr. Samuel White Thayer, who had graduated from the same medical college in Woodstock and had married Cornelia's sister Sarah in 1841.

[7] Together Williams and Thayer were civically active in the village of Northfield forming an Odd Fellows lodge and establishing a new Episcopal Church congregation in 1851.

While in Northfield he became close friends with Isaac B Howe and John C. Gault, engineers with the Vermont Central & Canada railroad.

[11] This temporarily split up the three friends as Williams took Gault with him to Chicago while Howe stayed in Northfield to get married and tie up a number of business dealings.

[13] By 1861 Howe was brought to Clinton to take over control of the Iowa roads and the following year the CI&N and CR&MR railroads were leased by the Galena completing the plan.

In July 1864 a grand consolidation took place where a small and little-known Chicago & Northwestern railroad was organized to assume control of the Galena in Illinois as well as its leased roads in Iowa, including the Mississippi bridge and ferry at Clinton, and a lucrative charter to Council Bluffs.

[1] On 17 June 1861, Cornelia Williams' brother, Officer Nehum M Platt, was shot and killed accidentally by Union troops during a demonstration in St. Louis.