He has been looking through his book and knows more about the
barometer than his teacher does.

'It consists,' the abbe continues, 'of a bent glass tube filled with
mercury, which rises and falls according to the weather. The shorter
leg of this tube is open; the other...the other...well, we'll see.
Here, Bastien, you're the tallest, get up on the chair and just feel
with your finger if the long leg is open or closed. I can't remember
for certain.'

Bastien climbs on the chair, stands as high as he can on tip-toe and
fumbles with his finger at the top of the long column. Then, with a
discreet smile spreading under the silky hairs of his dawning
moustache:

'Yes,' he says, 'that's it. The long leg is open at the top. There, I
can feel the hole.'

And Bastien, to confirm his mendacious statement, keeps wriggling his
forefinger at the top of the tube, while his fellow-conspirators
suppress their enjoyment as best they can.

'That will do,' says the unconscious abbe. 'You can get down, Bastien.
Take a note of it, boys: the longer leg of the barometer is open; take
a note of it. It's a thing you might forget; I had forgotten it
myself.'

Thus was physics taught. Things improved, however: a master came and
came to stay, one who knew that the long leg of the barometer is