 His book, "A History of Slavery and Serfdom" was extremely successful, being translated into eleven languages and serving as a textbook till the 1920s.He also wrote the entries on sumptuary laws and slavery in the 9th, 10th and 11th editions of the "Encyclopædia Britannica".Ingram was active in the fields of mathematics, archaeology, the classics, economics, etymology, law, literature, medieval manuscripts, poetry, religious speculation and Shakespearean criticism.