Here is some additional information on the original lyrics I found at: http://www.vesuvioinrete.it/funicolare/e_funicolare_funiculi.htm with the picture of the title page of the sheet music and midi file
The song was written by journalist Peppino Turco and was set by Luigi Denza in 1880. They drew the inspiration from the inauguration of the first funicular of Mt.Vesuvius. They composed this music in few hours, and in spite of that the song met with success. The famous melody was sang the first time in the rooms of Quisisana Hotel in Castellammare di Stabia. Turco and Denza presented it to the Piedigrotta's day in the same year. The success roused contributed to diffuse Neapolitan song in the world and to recall a lot of tourists.
Original text - Neapolitan dialect
Aieressera, oi' ne', me ne sagliette, tu saie addo'? Addo' 'stu core 'ngrato cchiu' dispietto farme nun po'! Addo' lo fuoco coce, ma si fuie te lassa sta! E nun te corre appriesso, nun te struie, 'ncielo a guarda'!... Jammo 'ncoppa, jammo ja', funiculi', funicula'!
Ne'... jammo da la terra a la montagna! no passo nc'e'! Se vede Francia, Proceta e la Spagna... Io veco a tte! Tirato co la fune, ditto 'nfatto, 'ncielo se va.. Se va comm' 'a lu viento a l'intrasatto, gue', saglie sa'! Jammo 'ncoppa, jammo ja', funiculi', funicula'!
Se n' 'e' sagliuta, oi' ne', se n' 'e' sagliuta la capa giĆ ! E' gghiuta, po' e' turnata, po' e' venuta... sta sempe cca'! La capa vota, vota, attuorno, attuorno, attuorno a tte! Sto core canta sempe nu taluorno Sposammo, oi' ne'! Jammo 'ncoppa, jammo ja', funiculi', funicula'! Do you know where I got on, yesterday evening, baby? Where this ungrateful heart can't be spiteful to me more! Where the fire burns, but if you run away it let you go! And it doesn't run after you, doesn't tire you, looking at sky!... Let go on, let go, let go, funiculi', funicula'!
English language text
We go from the ground to the mountain, baby! Without walking! You can see France, Procida and Spain... I see you! Pulled by a rope, no sooner said than done, we go to the skies.. We go like the wind all of a sudden, go up, go up! Let go on, let go, let go, funiculi', funicula'!
The head has already got on, baby, got on! It has gone, then returned, then come... It is still here! The head turns, turns, around, around, around you! This heart always sings one of these days Get married to me, baby! Let go on, let go, let go, funiculi', funicula'!