This method is frequently adopted in combined schemes of heating and ventilating; the fresh air is warmed by being passed over their surfaces previously to being admitted through the gratings into the room.
This opisthodomus was completely fenced in with bronze gratings; and the excavators believe it to have been adapted for use as an adytum (shrine).
The houses, built of stone and whitewashed, are square, substantial, flat-topped buildings, presenting to the street bare walls, with a few slits protected by iron gratings in place of windows.
It is true that in 1823 Fraunhofer, inspired by his observations upon gratings, had very nearly hit the mark.'
Abbe published a somewhat more complete investigation, also founded upon the phenomena presented by gratings.