510 Dr, Kidd’s Observations respecting 
on the same level with an area, about ten feet in breadth, 
which in part occupies the site of the ditch of the old t )wn 
and insulates a quadrangular projecting part of the whole 
building of the Museum. The laboratory itself is a single 
room sixty feet in length from east to west, and twenty-five 
in breadth; having an arched stone ceiling, the centre of which 
is seventeen feet above the level of the pavement. The walls 
of this room, which are nearly three feet in thickness, are con- 
structed of squared calcareous freestone, which I have reason 
to believe was dug from a quarry near Burford, and is tech- 
nically called Windrush stone, from the river of the same 
name. There are four windows in the upper part of the north 
side of the laboratory, formed in the curve of the arched ceil- 
ing; the dimensions of each of which are five feet by four 
and a half. 
There is no window either on the eastern or western side 
of the laboratory. 
On the south side there are two windows, one at each ex- 
tremity, looking into the area above described ; and these 
windows are placed at the usual distance from the ground, 
that is, about three feet: and all that part of the south side in- 
termediate to these two windows separates the laboratory from 
the quadrangular projecting part of the whole building of the 
Museum already mentioned. 
The saline efflorescence takes place most copiously on the 
north wall, and it occurs on various parts of it from nearly 
the level of the pavement to within three or four feet of the 
centre of the arched ceiling. It takes place also, though not 
so abundantly, on the east and west wails ; and also at the 
eastern and western extremity of the south wall; but it is 
