But-- "Don't you know the position of attention, mister!" demanded Cadet Pratt, with feigned anger.

"Your hands should hang naturally at your sides, the little finger touching the seam of the trousers." Now, in this inverted position the hands "hung" anything but "naturally" at the sides.

In fact, Bert had to hold his hands up in the air in order to have the little fingers touch the seams of the trousers.
Standing on his head, in this fashion, without support, was something that taxed all of Mr.Dodge's athletic powers.

He had to try over again, more than a half a dozen times, ere he achieved a decent performance of this gymnastic feat.
"Now, let us see how good a soldier you are, mister," commanded Yearling Pratt, turning around upon Plebe Anstey.
Anstey's cheeks were just a bit pale, from suppressed anger, but he speedily mastered this novel way of standing at attention, and did it to the satisfaction of the hazers.
Then Dick and Greg did it, and rather better than either of their predecessors.

The old gym.