A transport one cannot contain — Peep-Show

A sixpence at a Show and Diagram hint the answer. Like most of Dickinson's poems, it's hard to catch her mind without solving the riddle first. She used peep-show as base to develop another view unacceptable in her days. With sixpence, God watches the peep-show of our world.

A transport one cannot contain ¹
May yet a transport be－
Though God forbid it lift the lid－
Unto its Ecstasy!

A Diagram－of Rapture! ⁵
A sixpence at a Show－
With Holy Ghosts in Cages!
The Universe would go!

(F.212/J.184)

[1] transport one cannot contain:: peep-shows on a caravan cannot contain true objects. Peep-show:: a small exhibition of pictures, etc., viewed through a magnifying lens inserted in a small orifice _{(OED 1851)}.
[2] transport:: ecstasy of watching the peep-show.
[3] God:: a powerful man, owner of the show.
[5, 6] Diagram, Show:: a hint on peep-show.
[7] Holy Ghosts:: drawings.
[8] Universe, go:: our living world runs as a show for God.

There are two kinds of peep-shows, which we call 'back-shows' and 'caravan-shows.' The caravan-shows are much larger than the others, and are drawn by a horse or a donkey. . . . The scenes of them carawan shows is mostly upon recent battles and murders. They have a green-baize curtain at the back, which shuts out them as don't pay. . . . The back-shows are peep-shows that stand upon trussels, and are so small as to admit of being carried on the back. The scenery is about 18 inches to 2 foot in length, and about 15 inches high. . . . I've 'Napoleon's Return from Helba.' ─ London Labour and the London Poor (1861)