THREE:As the boys rode along, their attention was drawn to some tall ladders that rose above the buildings, and they eagerly asked the Doctor what those ladders were for. They could not see the use of climbing up in the air and then coming down again; and, altogether, the things were a mystery to them. A few words explained the matter. The ladders were nothing more nor less than fire-lookouts, and were elevated above the buildings so that the watchmen could have an unobstructed view. A bell was attached to each ladder, and by means of it a warning-signal was given in case of a threatened conflagration. Fires are frequent in Tokio, and some of them have done immense damage. The city is mostly built of wood; and when a fire breaks out and a high wind is blowing, the result is often disastrous to an enormous extent.The mint at Osaka is one of the most noted enterprises which the government of Japan has undertaken, and likewise one of the most successful. When it was founded it was under foreign supervision, and the most of the employ��s were from Europe; but year by year the Japanese have learned how to conduct its machinery, and have relieved the foreigners of the labor of managing it. The direction is Japanese, and so are the heads of the departments, and the employ��s from highest to lowest. When the mint was established, the machinery for it was imported from Europe, but at present it is all made by the Japanese, in their own factory attached to the mint.