W.E. Heitland (1847-1935), After Many Years: A Tale of Experiences & Impressions Gathered in the Course of an Obscure Life
(Cambridge: Cambridge University Press, 1926), pp. 75-76 (at Shrewsbury):
The normal punishments formed a sort of tariff thus
(1) Penal Marks or 'Penals.' The unit was 50 lines from Paradise Lost. These had to be shewn up on Saturday, and each Monday the place for beginning was given out for the week, so that one could not write them on Sunday. The Punishments-master saw to this, and he sometimes accepted a number of Penals less than that due, on the ground of better handwriting.
(2) Two Penals = one 'Detention.' A Detention consisted in your being kept in half an hour after Second Lesson, from 12 to 12 30. You were supposed to spend the time learning by heart a fixed portion of the Latin Grammar, written in Latin as was then the fashion. On Tuesdays those 'detained' during the week were called up to repeat this to the Headmaster. Failure implied further punishment, but a tolerant management made this result rare.
(3) Two Detentions = one 'Idle List.' Idle List consisted in your being kept in for an hour at least,
compelled to bring work and do it then and there.
But you had no further liability once the period
The detentive forms of punishment were both
evils, but the 'Detentions' had no redeeming merit
whatever. An old penalty of solitary confinement
in a sort of dark cage had ceased to be used in my
time, but there were traditions of its use not many
years before. The cage, Butlerian (or earlier?) still
stood in the Fifth Form room. I do not remember
gating as a Shrewsbury punishment. Flogging was
done with a 'birch' of broom-twigs. A monitor was
in attendance to lift the culprit's shirt. It was the
right thing for him to place himself so that the more
pungent ends of the birch caught his trousered leg
and minimized the designed effect. The ceremony
was of rare occurrence. As a sincere and final
penalty it had its merits.
Hat tip: Alan Crease.