Dr. Wolfred David Emelius Nelson was born on April 10, 1846, in Montreal, Quebec, grandson of Wolfred Nelson (1791-1863), a Montreal doctor and politician.

He was a physician, sanitation expert, and author. He was educated at McGill University and began his practice in Canada. In 1880, he moved to Panama for 5 years. He also spent years in South and Central America where he was collecting data on climatology and tropical diseases. In 1899, he moved to New York to practice. Dr. Nelson made yellow fever his special study and wrote exhaustively on this and other tropical diseases. In 1904, he went to Cuba as a special sanitary commissioner and for his work in the prevention of tropical diseases, Queen Isabella of Spain bestowed upon him the title of Commander of the Order. He was a member of the New York State Medical Society, the Natural History Society of Montreal, and was elected a fellow of the Royal Geographic Society in 1894. He was a founder of the Canadian Society of New York and a founder and president of the New York Graduates Society of McGill University.

In 1875, he married Frederika Woodbridge De Long (1853–). He died on January 15, 1913, in New York, New York.

James Nelson was born in 1830, in Belfast, Ireland.

In 1840, he was brought to Montreal, Quebec by his parents. After receiving his education in Montreal, he formed a partnership with John W. Hopkins in 1853 and two years later they invited Frederick Lawford, a talented young designer from London, England, to join them. Their firm Hopkins, Lawford & Nelson (1855-1859) can be credited with some of the outstanding examples of Gothic Revival and Renaissance Revival work erected in Canada. After the death of Lawford in 1866, Nelson continued to work alone or with Charles Ballard. In 1884, Nelson formed a partnership with Christopher Clift. One of their employees was H. Charles Nelson, son of James, who worked in their office as a draftsman. The firm was dissolved in December 1890 and Nelson worked under his own name until 1894 when his son joined him in a new partnership. That same year Nelson was elected President of the Province of Quebec Association of Architects and remained active in the profession until 1909.

In 1909, he moved to Arundel, Quebec, where he died on February 18, 1919.