Known in his lifetime as a medical and theological writer, he was also responsible in his capacity as physician to Michael Faraday for the term "electrode", a fact not known until well into the 20th century.
His father was rector of the parish, and died before Nicoll was two years old; his mother was Ann, daughter of George Hatch of Windsor.
[2] In 1806 Nicoll became a student at St George's Hospital, and in 1809 received the diploma of membership of the College of Surgeons of England.
[2] Nicoll began to write aon medicine in the London Medical Repository in 1819; his first separate publication, Tentamen Nosologicum had already appeared there, a general classification of diseases based upon their symptoms.
The History of the Human Œconomy appeared in 1819, and suggests a general physiological method of inquiry in clinical medicine.
This was first read before an association of physicians in Ireland on 6 December 1819; he proposed that erethism of the cranial brain is due to impressions on the anticerebral extremities of nerves, but this theory went beyond his actual observations.