Then, before they had had a chance to look around or feel at home, the conductor, who stood at the back, shouted, "Low bridge!" and everybody ducked their heads while the great bus went under the elevated railroad. Mary Jane felt, truly, as though she must be a person in a story book--Arabian Nights or something marvelous--because surely the things that were happening to her weren't _really_ happening. But after the elevated was passed, the bus rolled out onto Michigan Boulevard and Mary Jane settled herself comfortably in her front seat with her mother, smiled across the aisle to Alice and her father and began to feel really at home in her high perch. By the time the bus had turned northward and crossed the river, she began to feel that riding on the top of a bus was the thing she'd been wanting to do all her life. It was such fun to sit up high and watch the lake, so blue and beautiful in the sunshine, the trees just getting a tinge of green at the tips, the pretty houses that lined the parkway, the people--it seemed as everybody in Chicago must be out in their 'tother best clothes--and most of all, it was fun to watch the automobiles dart in and out of the crowd, around the bus and beside it, till Mary Jane was sure their driver must be some wonderful being to be able to manage so that everybody stayed alive! "Here, Mary Jane," said Mr. Merrill, interrupting Mary Jane's sight-seeing, "don't you want to pay your fare--Alice is paying ours." He slipped two dimes into her hand just as the conductor stepped to the front of the bus. Mary Jane wasn't quite sure what she was to do with the dimes till she noticed that the conductor had in his hand a queer-looking thing like a clock, only it had a hole in the top just the right size for a dime. Into that hole Mary Jane dropped a dime. And--"ding_ding_!" went a musical little bell somewhere in the "clock." Then she dropped the other dime. And again the bell sounded, "ding_ding_!" just as though it tried to say "Thank _you_!" that way. Alice then dropped her two dimes and Mary Jane had the fun of hearing the bell again. She thought she wouldn't do a thing but watch the conductor and listen to his bell all the time he collected fares, but just as he stepped back to get the next folks' money the bus passed in front of the queer old stone building with great tower that Mr. Merrill said was the city water works building, and of course that meant the girls wanted to hear about when it was built and hear again the story Mr. Merrill had started to tell them several evenings before about how the great Chicago fire started and how it burned up to this very spot they were now passing. Somehow, being at that place and seeing the one building that stood through the fire made the history stories seem very plain and there were a lot of questions to be asked and answered.