Report on the Trials of Implements at Readinj. 
687 
it was put together green and damp. The stack was a round 
one, on a 20-foot bottom. The flue was formed with 9-inch 
socketed earthenware pipes laid in the ground, and the shaft 
was made by a wooden cage about (3 feet high and 21 inches 
square. 
On the 24th, before the stack was completed, the heat 
on the N.E. was 132', and the fan was set to work. The 
power employed was a 4-horse-power vertical engine, made by 
Messrs. Hindley, of Bourton (the same engine which had been 
used for the dynamometer trials). The strap, running from a 
30-foot fly-wheel on to a 3-foot pulley, gave a speed of about 
1400 revolutions per minute ; subsequently this was increased 
to 1800 revolutions. The fan was worked for one hour and 
twenty minutes ; and again, after an interval of forty minutes, 
for forty minutes, making in all two hours' work. This had 
the effect of reducing the average temperature about 23'. 
On the 26th the fan was worked for six hours without pro- 
ducing any appreciable effect. As the water which was dis- 
charged from the fan was very dirty, one of the Judges 
suggested to Mr. Greening's representative that perhaps there 
was a leakage somewhere ; and another Judge, putting his 
hand above one of the joints of the socketed pipes which formed 
the flue, found a strong indraught of air. This defect was 
remedied, but on the 27th and 28th, though the fan was worked 
for five and a quarter hours on the first of these days, and almost 
throughout the day on the 28th, the temperature on the N. 
and S.E. continued to rise until, at 4 P.M. on the latter 
day, the heat had reached 150' and 142° at these two points. 
The observations of the temperature of this stack were only 
approximate, as Mr. Greening used some of his " One-and-x\ll " 
harvest-saving thermometers. In these instruments the niceties 
of graduation are dispensed with. Mr. Greening, sagelv 
divining that it would be useless to give an ordinary labourer 
instructions to commence exhausting at so many degrees, 
and to cease exhausting when the thermometer reached x 
degrees, marks his thermometer on the face of it with express 
directions : " Commence Exhausting for Hay," " Cease Ex- 
hausting," " Firing-point," &c., just as Fahrenheit marked his 
thermometer with "Freezing" and "Boiling" points, — with 
perhaps this difference, that the latter based his scale upon 
accurate observation and experience. The directions given 
on the " One-and-AU " thermometer, with the temperatures 
at which they are fixed, are believed to be as follows: — 
"Firing-point," 212'; "Commence Exhausting (Hay)," 120'; 
" Cease for Hay," " Commence for Corn," 80' ; " Cease 
Exhaust (Corn)," 60'. 
It must be observed that all the other exhibitors of fans had 
