It is called a “dark lantern”. In the days before electric lights, this was like a modern flash light that can be turned on and off, by opening the shutter.
One could keep the candle lit, even while one wanted to creap along unseen in the dark, because lucifer matches weren't all that easy to come by either.
Once again, I get to quote from Dickens - In Ch. 39 of The Pickwick Papers, Mr. Pickwick brings such a lantern along on a night time clandestine escapade with amusing results
It was at this stage of the undertaking that Mr. Pickwick, with many smiles and various other indications of great self-satisfaction, produced from one of his coat pockets a dark lantern, with which he had specially provided himself for the occasion, and the great mechanical beauty of which he proceeded to explain to Mr. Winkle, as they walked along, to the no small surprise of the few stragglers they met.
‘I should have been the better for something of this kind, in my last garden expedition, at night; eh, Sam?’ said Mr. Pickwick, looking good-humouredly round at his follower, who was trudging behind.
‘Wery nice things, if they’re managed properly, Sir,’ replied Mr. Weller; ‘but wen you don’t want to be seen, I think they’re more useful arter the candle’s gone out, than wen it’s alight.’
Mr. Pickwick appeared struck by Sam’s remarks, for he put the lantern into his pocket again, and they walked on in silence.
‘Down here, Sir,’ said Sam. ‘Let me lead the way. This is the lane, Sir.’
Down the lane they went, and dark enough it was. Mr. Pickwick brought out the lantern, once or twice, as they groped their way along, and threw a very brilliant little tunnel of light before them, about a foot in diameter. It was very pretty to look at, but seemed to have the effect of rendering surrounding objects rather darker than before.
At length they arrived at the large stone. Here Sam recommended his master and Mr. Winkle to seat themselves, while he reconnoitred, and ascertained whether Mary was yet in waiting.
After an absence of five or ten minutes, Sam returned to say that the gate was opened, and all quiet. Following him with stealthy tread, Mr. Pickwick and Mr. Winkle soon found themselves in the garden. Here everybody said, ‘Hush!’ a good many times; and that being done, no one seemed to have any very distinct apprehension of what was to be done next.
‘Is Miss Allen in the garden yet, Mary?’ inquired Mr. Winkle, much agitated.
‘I don’t know, sir,’ replied the pretty housemaid. ‘The best thing to be done, sir, will be for Mr. Weller to give you a hoist up into the tree, and perhaps Mr. Pickwick will have the goodness to see that nobody comes up the lane, while I watch at the other end of the garden. Goodness gracious, what’s that?’
‘That ‘ere blessed lantern ‘ull be the death on us all,’ exclaimed Sam peevishly. ‘Take care wot you’re a-doin’ on, sir; you’re a-sendin’ a blaze o’ light, right into the back parlour winder.’
‘Dear me!’ said Mr. Pickwick, turning hastily aside, ‘I didn’t mean to do that.’
‘Now, it’s in the next house, sir,’ remonstrated Sam.
‘Bless my heart!’ exclaimed Mr. Pickwick, turning round again.
‘Now, it’s in the stable, and they’ll think the place is afire,’ said Sam. ‘Shut it up, sir, can’t you?’
‘It’s the most extraordinary lantern I ever met with, in all my life!’ exclaimed Mr. Pickwick, greatly bewildered by the effects he had so unintentionally produced. ‘I never saw such a powerful reflector.’
‘It’ll be vun too powerful for us, if you keep blazin’ avay in that manner, sir,’ replied Sam, as Mr. Pickwick, after various unsuccessful efforts, managed to close the slide…"
etc etc.
edit to add: complete e-text of that memorable work of Dickens
Jamais l'or n'a perdu la plus petite occasion de se montrer stupide. -Balzac
