Glacier Montanvert was the common name in the 18th century for a portion of the Alps glacier, now known as Mer de Glace, on the northern slopes of the Mont Blanc massif. Alternative spellings of Montanvert include Montainvert and Montvers. The Glacier Montanvert was a popular tourist destination of European travellers and is referenced in numerous travel writings and novels of the time.
Wikipedia

A One Day  Journey from Chamouny:

Bædeker Switzerland (1877) Route 53 page 222 & 223