It is a double-barrelled gun, but you must use your eyes for bullets, instead of leaden balls.

See!"-- and he took a fine pair of field-glasses from the case, moved the screw a little, and held them before Dodo's eyes--"what do you see down there in the grass ?" "Why, it's a Robin, but how big it looks! Every feather shows by itself, and it has white rings round its eyes like spectacles.

I never saw them before, I'm sure." Then, as the Doctor handed the glasses to Nat, Dodo looked in her lap, expecting to find the bird there instead of a hundred feet away.
"This is jolly!" cried Nat, taking a peep and passing the glasses to Rap, who put them to his eyes, gave a little "ah," and looked through them until the Doctor said, "That will do now.

Olive shall keep the glasses, and whenever you children want them she will give them to you; but you must be careful never to scratch them or rub your fingers over the lenses at either end.

With this magnifying instrument you will be able to see the shape of beaks and wings, and many color markings you would never notice otherwise.