In the late 1890s, deteriorating health forced Engelhardt to give up personal observing, and he gave all his equipment to Kazan University, of which his friend and fellow astronomer Dmitri Dubyago was rector.

Engelhardt was awarded an honorary doctorate by Kazan University in 1889, and in 1890 he was made a corresponding member of the Russian Academy of Sciences.

Later, at the request of the critic Vladimir Stasov (a law school classmate), Engelhardt published his memoirs of Glinka and the composer Alexander Dargomyzhsky.

Engelhardt's correspondence with leading cultural figures (Glinka, Stasov, Franz Liszt, G. Bulow) is considered of historical value.

By decision of the XIV Congress of the International Astronomical Union, the Moon crater Engel'gardt was named in Engelhardt's honor.