Quote
Portsea Island is a flat fertile country, about sixteen miles in circumference, joined to the main land by a stone bridge of one arch, called Portsbridge, three miles and a half from Portsmouth, where there is a small garrison; the land in this island is esteemed as good as any in the kingdom: there are several good farms on it, consisting chiefly of arable land, some meadow and pasture, these hardly ever fail of yielding very plentiful crops.
— Author unknown (1790) A New Portsmouth Guide; Being a Description of the ancient and present State of the Place. J. Breadhower, Portsmouth. source
Todo
There’s a good sketch of the bridge, contemporaneous with the viewing platform being built at the Coach and Horses.