He was too hopelessly invisible to carry any weight with strangers.
The assistance of Mabel would not be of much value. The police?
Before they could be got and the getting of them presented
difficulties the burglars would have cleared away with their sacks
of silver.

Gerald stopped and thought hard; he held his head with both hands
to do it. You know the way the same as you sometimes do for
simple equations or the dates of the battles of the Civil War.

Then with pencil, note-book, a window-ledge, and all the
cleverness he could find at the moment, he wrote: "You know the
room where the silver is. Burglars are burgling it, the thick door is
picked. Send a man for police. I will follow the burglars if they get
away ere police arrive on the spot."

He hesitated a moment, and ended "From a Friend this is not a
sell."

This letter, tied tightly round a stone by means of a shoelace,
thundered through the window of the room where Mabel and her
aunt, in the ardour of reunion, were enjoying a supper of unusual
charm stewed plums, cream, sponge-cakes, custard in cups, and
cold bread-and-butter pudding.

Gerald, in hungry invisibility, looked wistfully at the supper before
he threw the stone. He waited till the shrieks had died away, saw
the stone picked up, the warning letter read.