Isinglass is a synonym for any transparent material that is used to bring sunlight indoors while providing protection from the wind, rain and cold.
Originally referred to as Mica Windows as Mica was the mineral used by the Romans to create lightweight, flexible and transparent window covering, Mica windows were in fact the earliest form of windows in the United States. Because these thin sheets were transparent, they were called isinglass windows.
The Model T Ford of the 1920&30's was open on the sides with a detachable, canopy roof. The canopy had no windows, however, because using glass windows would make the car too heavy, the manufacturers began making celluloid windows they called isinglass curtains.
Today, isinglass curtains are the vinyl windows zipped into the canvas tops used on a motorboat. These curtains can be rolled up and stored when the boat is in dry dock or when the weather is nice and not needed. However, they can then easily be unrolled and zipped into place any time "
there's a change in the weather."