when charles dickens visited us in 1840, he was truly blown away by high water pressure on the fourth floor of the hotel he was staying in. nowhere in europe had he experienced that. this technology was doing something to support the life and the growth of the city. philadelphia, throughout the 19th century, was the major industrial city of the united states. all of these industries used water from this system. and it served as a prototype for many american cities, including pittsburgh and new york. man: new york city went to philadelphia and said, "you know, we're thinking of developing a hudson river water supply -- what do you suggest we do?" and they said, "we've had "a lot of problems on the schuylkill. "don't go to the hudson river. go to the upland and work by gravity." and that's what new york city did. they first went to the hudson highlands, but 150 years later, it went to the delaware highlands. and really diverted the water that normally went to philadelphia to new york city. i don't think they anticipated that. narrator: the majority of new york city's drinking water come

. >> jimmy: yeah, charles dickens.s. know what i'm saying? but -- >> jimmy: "i got you, charles." yeah, yeah. i think we should go into business together on something. >> we should. plus you got this -- the show. we can have product placement. we can sell "late night" jimmy mugs. [ laughter ] >> jimmy: right? >> you mind if i have some of your water? [ laughter ] >> jimmy: no, please, you -- of course you can have some of my water. absolutely. it's straight vodka, by the way. yeah, it's -- no, yeah. >> i thought you said you didn't use drugs, jimmy. [ laughter ] >> jimmy: something is good in there. it's pretty good. i have a couple ideas. i have a couple ideas. i have one idea -- i have two ideas. maybe you can shoot them down. one is called "pool stool." yeah. [ light laughter ] we might have to change the name, but what you do is you put -- [ laughter ] they're just stools that are weighted that you put in a pool, in case you want to sit in the pool and hang out. >> oh, inside the pool? >> jimmy: yeah, i want to sit