1887. ‘Death of Blue Billy,’ in Chamb. Jour., Dec. 17, p. 812. Blue
Billy is the technical name given to the lime rendered foul in the
purification of the gas.
Blue Blanket, subs. (common).—1. The sky. This simile is an old one;
Defoe’s use of it may probably have been suggested by Shakspeare’s
‘blanket of the dark’ (Macbeth, I., v.).
c. 1720. Defoe, Hist. of Devil, quoted in N. and Q., 7 S., ii.,
289; see also 7 S., ii., 492. We must be content till we come on
the other side the blue blanket, and then we shall know the whole
story.
1877. Greenwood, Under the Blue Blanket. The vagrant brotherhood
have several slang terms for sleeping out in a field or meadow. It
is called ‘snoozing in Hedge Square’; ‘dossing with the daisies’;
and ‘lying under the blue blanket.’
The French say, ‘coucher à l’hotel de l’Etoile,’ i.e., ‘to sleep at the
Star Hotel’; while in the Fourbesque, or Italian cant, heaven or the
sky is termed copertore, a covering or blanket.