it was just a public noose -- nuissance, you might say, and pratches a health hazard. so people were excited to find new forms of transportation. and they came up with one we're all familiar with, the cable car. so here on the left you'll see a cable car next to the horse car on the right. the cable car was a great leap forward because it cut the horses out of the equation. cable cars were a lot more energy efficient. they were very popular in cities all across the united states, including chicago. and they really took over in san francisco because cable cars could climb hills were horses couldn't, opening up development in parts of the city where before there hadn't been any. but cable cars had their drawbacks, too. a cablecar can only go nine miles an hour, as fast as the cable under the street pulling it. cables have a hard time pulling backwards, changing direction, investing in the infrastructure to put the cable in the street is very costly. so you have a lot of upfront costs. if a company wanted to run just one cable car, they had to start up the power house to