"Is San Francisco the only city where they have those cars?" asked Harriet. "Oh, no," answered Grandma. "They have them now in several of the other large cities. San Francisco was the first city to have them. The hills there are so steep that it was out of the question to use horses. Something had to be invented, and Andrew S. Hallidie planned this system which has been used successfully ever since 1873." "Weren't there any people in those days who thought the cable cars were dangerous, Mother?" asked Harriet's father slyly. "Oh, dear me, yes," replied his mother. "The gripman himself lost his courage, I remember, on one of the very first trips and stopped his car at the top of his first steep hill. He got off the car and said that, as he had a wife and children, he did not think it would be right for him to take the car down such a hill. The passengers said it was not a case of right or wrong but a case of being scared, and they insisted upon his getting on again and taking them to their journey's end." "There goes another electric car, Grandma!" said Harriet who was looking out the window. "It goes a good deal faster than a horse car, doesn't it?" "I should think it did," answered Grandma, "In contrast with travel on horse cars, going as fast as that must seem like flying. How can it be possible to get power enough to drive a big car like that!" "It comes right along that overhead wire," answered Harriet's father. "Oh, yes, I know that from what I have read," continued Grandma. "And it is conducted to the car along that long iron rod which runs from the overhead wire to the car. What is it you call that?" "The trolley," said Mr. Lewis. "Then what really happens after the electricity has reached the car?" "This current of electricity runs to those cylinders in front of the motorman. Then it is where it can be controlled. By the turning of a crank the motorman can turn on the power to start the motor and drive the car ahead, or he can shut it off and make the car stand still. Just as steam power turns the wheels of the locomotive, so electric power turns the wheels of these cars." "It is very mysterious after all," said Grandma. "It certainly is," assented her son. "Oliver Wendell Holmes says it is like witchcraft. Have you read his poem which says: 'Since then on many a car you'll see A broomstick, plain as plain can be; On every stick there's a witch astride-- The string, you see, to her leg is tied!'" Grandma and Harriet laughed. "How fast are these cars going?" asked Grandma. "About ten miles an hour including the stops. Probably the rate without stops is about fifteen miles," answered Mr. Lewis. "There never could be power enough in electricity to drive the car much faster than that, I suppose?" said Grandma.