THRJ MICRO-ORGANISMS PRESENT IN THE ATMOSPHERE. 
151 
Addendum. 
(Added April 19, 1887.) 
The following experiments, made by this new method on St. Paid’s Cathedral, may 
be recorded as further illustrations of the accuracy of the process. The experiments 
were made on November 19, 1886, the air being examined on the Golden Gallery, 
which is at the top of the dome; on the Stone Gallery, which encircles the base of the 
dome ; and in the Churchyard at the bottom of the Cathedral. 
St. Paul’s, Golden Gallery. —November 19, 1886. Wind due S., strong. Roads wet, 
pavement dry. 1.10 to 2.20 p.m. 9 0- 7 C. The air was aspirated through three 
tubes alternately. 
No. 1 . Volume of air= 18 litres. 
Construction of plugs. — (a) Sugared glass-wool. 
(f) Sugared glass-wool and sugar-powder. 
Rate. —3‘3 strokes per minute. (Tube exposed 19 minutes.) 
8 moulds. 
Colonies in flasks. — (a) 18 
(b) 0 . 
0 liq. 
No. 2. Volume of air—21 litres. 
Construction of jilugs. —(a) Glass-wool. 
( b ) Sugared glass-wool and sugar-powder. 
Rate. —5 strokes per minute. (Tube exposed 18 minutes.) 
s-y 1 • ■ n 1 . . F14 moulds. 
Colonies m flasks.— (a) 23 
0 liq. 
(b) 0. 
No. 3. Volume of air= 18 litres. 
Construction of plugs. —( a) Glass-wool. 
(b) Sugared glass-wool and sugar-powder. 
Rate. —6'6 strokes per minute. (Tube exposed 10 minutes.) 
sy i • • n i / \ ^ r 15 moulds. 
Colonies m flasks. — (a) 20- 
0 liq. 
(b) 0. 
Control-tube exposed 75 minutes. 
Colonies in flask. —1 (mould). 
Stone Gallery. — November 19, 1886. 2.56 p.m. to 3.52 p.m. 10°'5 C. 
No. 1 . Volume of air — 1 2 litres. 
