"Are you sure?" asked Mrs. Simpson, one of the ladies in charge of the children. "Oh, yes, ma'am. There's no danger," declared the man. He had jumped from his seat and was looking at the floor of the bridge under the front wheels of the truck. "Keep quiet, every one!" ordered Mr. Blake, one of the gentlemen who had agreed to help the ladies look after the children. "Don't scream or cry, and move as quietly as you can. The easier you move the less danger there will be. The bridge hasn't quite broken in two yet." But it was in grave danger of doing that, as Mr. Blake saw, and he was fearful that a bad accident would soon happen. However, the thing to do now was to get all the children off the truck, over the bridge, and safe on solid ground. After that it might be possible to get the truck over and keep on to the picnic. One by one the children, including the Bobbsey twins, started to get off the truck. They moved as carefully as they could, for they felt that they were like skaters on thin ice. The least quick movement might break something. The truck that had gotten safely over the bridge had come to a stop, and children and grown folks were piling off it to see what they could do to save those in danger on the broken bridge. And while the work of rescue is going on I will take a moment or two to tell my new readers something about the Bobbsey twins. Those of you who have read the other books in this series do not need to be introduced to Bert, Nan, Flossie and Freddie. Those were the names of the four children. Bert and Nan were the older twins, and Flossie and Freddie the younger. You are first told about them in the book called "The Bobbsey Twins," and in that you learn that the Bobbsey family, consisting of Mr. and Mrs. Richard Bobbsey and their four children, lived in Lakeport, an eastern city on the shore of Lake Metoka, where Mr. Bobbsey had a lumber business. In the family, though not exactly members of it, were Dinah, the jolly, fat, colored cook, and Sam Johnson, her husband. Then we must not forget Snap, the dog, and Snoop, the big cat. Following the first book are a number of volumes telling of the adventures of the Bobbsey twins. They went to the country to visit Uncle Daniel, and at the seashore they had fun at the home of Uncle William. After that the Bobbseys enjoyed a trip in a houseboat, they journeyed to a great city, camped on Blueberry Island, saw the sights of Washington and even sailed to sea. As if this was not enough Mr. and Mrs. Bobbsey took their children on a western trip among the cowboys, and just before the present story opens Bert and Nan, with Flossie and Freddie, had come back from Cedar Camp, where they had had some exciting adventures. Now it was summer again, and one of the first delights of that season was the Sunday school picnic which had started off so well but which seemed likely now to end in an accident.