In "The Adventures of the Speckled Band," what are the three odd things that Sherlock Holmes noticed in Julia's room?

The first odd items in what was Julia's room are the bell
pull which has no apparent connection and the ventilator which, instead of being
connected to the outside, is placed on the wall of the adjoining
bedroom-

“They
seem to have been of a most interesting character—dummy bell-ropes, and ventilators
which do not
ventilate."

Holmes has
anticipated these two elements, and the third clue helps him reach his conclusion to the
mystery. It is the positioning of the bed in the chamber which is the final
clue-

“It was
clamped to the floor. Did you ever see a bed fastened like that
before?”