"LET'S go to the Tower on top of a 'bus," clamoured the little girls, and it did not take long for them to scramble up on to the first one that came along. "It is so nice and wobbly," they declared, "and the people in the streets seem so far below." If one gets a seat just back of the driver, who is generally a jovial good fellow, he will tell you a lot about London, as he drives along, for these drivers are a sociable class of men. It is wonderful to see them guiding the big clumsy 'buses through the mass of people and vehicles of all kinds--costers' carts, automobiles, big lumbering wagons, and hansom cabs flitting about like busy flies. As often as not you will see a wagon, with a big load of hay, nearly blocking up the street, and next to it a stylish carriage with footmen in livery. Oh, you can see almost anything in the London streets. But the picturesque old omnibuses are soon to disappear, and automobile 'buses are to take their places. I must tell you what a coster is. Costers are people who go to the great London market, called Covent Garden, and buy cheap vegetables and fruits and flowers, and sell them in the poorer parts of the city. The coster men dress in velveteen suits trimmed with rows and rows of pearl buttons, which they call "pearlies." They are very proud of these costumes. The women wear bright, gaudily coloured dresses, and very big hats, covered with feathers. They hawk their wares about in barrows or little carts, drawn by such a tiny donkey (a "moke" as the costers call it), that you wonder how he is able to pull a whole family of costers as well as a big load of vegetables, as they often do. "Edith, that is St. Paul's Cathedral just ahead of us; you can see its big dome for miles around, and now we are in the old part of London," explained Miss Winton. "Just beyond is Bunhill Fields, where Daniel Defoe who wrote that immortal children's story--'Robinson Crusoe'--is buried. A plain shaft or obelisk rises above his grave, and not so very long ago the children of England were asked to give a penny each toward building this monument to the memory of the author of their favourite story-book. Many children responded and enough money was raised for the purpose. You will see that the inscription on it tells the story." The little girls were much impressed, and Edith said she would tell Clarence and Eleanor about it, as they had just been reading about Robinson Crusoe and his desert island. "Are not the 'Beefeaters' splendid?" said Adelaide, as they passed through the old gateway into the Tower of London. "There is the one, Miss Winton, who talked with mamma and me the last time we were here. I believe he remembers me and is coming this way. He had a tame raven which he showed us. See, Edith, there are a number of ravens flying about; they make their home among the old buildings, and the keepers feed them."