Then he reached out and tried to pull the outside shutter along in its own grooves.
"Stuck with a bit of ice," Dave reported.

"Harry, just bring the kettle." Darrin then poured some of the boiling water upon the sill, where the shutter stuck.

At his next effort the shutter moved.

Dave closed it and pegged it so securely that no trick from the outside could loosen that shutter.
This was done in turn to all the other windows.

Feeling secure now, the Grammar School boys found themselves drowsy.