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had the rough model made which I show here this evening. 
Each side of this box or room is made of thin layers of 
cotton wool sewn between two pieces of cloth, with a glass 
in front, which serves equally as door and window. A coni- 
cal-shaped piece made of stout paper is pasted to a square 
frame at its base, which tits against one end of the room. 
An ordinary glass funnel is placed in this cone with its stem 
passing through the apex which is firmly tied round it, 
and an india-rubber tube communicating with a pair of 
bellows is put on the end of the stem : the large end of the 
funnel is covered with a thin layer of cotton wool placed 
between two pieces of cloth, and the whole fixed round the 
funnel edge by means of an elastic band. When the window 
at the other end of the room is opened and the bellows 
worked, a current of air passes through a layer of cotton 
wool placed between two pieces of cloth on the mouth of the 
funnel and then through that at the end of the room, moves 
bodily along the room and escapes at the window, little or 
no special currents or draughts being apparently produced. 
This I observed by previously filling the room with fumes. 
The force of the air, by passing through the two layers of 
cotton wool, was evidently equally distributed throughout 
the whole area of the room. My first experiment with 
this arrangement was made by simply working the bel- 
lows for about twenty minutes to endeavour to drive 
the impure air, with • its floating particles and spores, 
out of the room by passing into it the filtered air from 
the bellows; then boiling one-half of some flour paste 
in a basin inside the room for a minute or two, and 
lastly, closing the window with the glass, the other half 
of the paste being boiled in a similar basin and left outside 
exposed to the ordinary or contaminated air. After a few 
days the difference between the two pastes was very marked, 
the surface of the one left outside the room was completely 
covered with fungus, whereas, only 4 or 5 little specks of 
