( 4 Z ) 
18 Inches Diameter round the Axis, juft where the 
Pipe is inferred into the Cafe, whereby the Pipe 
communicates with all the Cavities 5 and as the 
Wheel is turn’d fwiftly round, the Air which comes 
from the fick Room, is taken in at the Center of the 
Wheel, and driven to the Circumference, fo as to 
go out with great Swiftnefs at the Blowing* Pipe B, 
fix’d to the faid Circumference. 
As the foul Air is drawn away from the fick. 
Rooms, the Air in the neighbouring Apartments 
will gradually come into the Room through the 
fmaileft PafTages : Eut there is a Contrivance to 
apply the Pipes which go to the fick Room to the 
Blowing-Pipe 8, while the Sucking-Pipe receives its 
Air only from the Room where the Machine (lands.. 
By this means frefli Air may be driven into the fick 
Room after the foul has been drawn out. 
This Machine would be of great ufe in allHofpi- 
tals, and in Prifons : It would aifo ferve very well 
to convey warm or cold Air into any diftant Room ; 
nay, to perfume it iufenfibly, upon occafion. 
Fig. 2. Reprefents the Infide of the Flat of the 
Wheel which is fartheit from the Handle,, and next 
to the Sucking-Pipe. 
1, 2, 3, 4. Reprefents the Cavity or Hole which 
receives the Air round the Axis, having about it a 
circular Plate of Iron to hold all firm ; which Plate 
is made faft to the Wood and to the Iron Crofs that 
has the Axis in it. 
ggg-> Denotes, by a prick’d Circle, a narrow Ring 
of thick Blaokettiog, which (byprefling againfl the 
outfide Cafe, whilft it is fix’d to the ouefide of the 
Flat of the Wheel) makes the PafTage into the 
Wheel tight. _ H H H, is 
