As the islands are narrow and mountainous there are no great rivers and none available for important navigation. None of the rivers exceed 200 miles in length. Although Japan is situated much further south than Great Britain, its northern extremity being in about the same latitude as Cornwall, its climate is, on the whole, not unlike that of this country. Of course the climate of such a mountainous country and one extending over 14 degrees of latitude varies considerably. That of the island of Yesso, for example, is in winter rigorous to a degree, a fact in some measure caused by a cold current which flows down its eastern shores from the Sea of Okohotsk. Professor Rein, who has given great attention to the matter of the Japanese climate, has remarked in reference thereto: "The climate of Japan reflects the characteristics of that of the neighbouring continent, and exhibits like that two great annual contrasts--a hot, damp summer and a cold relatively dry winter; these two seasons lie under the sway of the monsoons, but the neighbouring seas weaken the effects of these winds and mitigate their extremes in such a manner that neither the summer heat nor the cold of winter attain the same height in Japan as in China at the same latitudes. Spring and autumn are extremely agreeable seasons; the oppressive summer heat does not last long, and in winter the contrast between the nightly frosts and the midday heat, produced by considerable insulation but still more by the raw northerly winds, causes frequent chills, though the prevailing bright sky makes the season of the year much more endurable than in many other regions where the winter cold is equal. As a fact the climate of Japan agrees very well with most Europeans, so that people have already begun to look upon certain localities as climatic watering-places where the inhabitant of Hong Kong and Shanghai can find refuge from the oppressive heat of summer and invigorate his health." The mean annual temperature of Tokio is about 56 deg. The lowest temperature is in January or February, when the thermometer seldom falls below 25 deg., the highest in August, when it sometimes rises to 95 deg. or 100 deg. in the shade, the average being 82 deg. The Japanese suffer a good deal from the effects of the wintry weather, bronchial, chest, and rheumatic affections being prevalent. The dwellings of the people, somewhat flimsy in construction as they are, are not well adapted to withstand the effects of a low temperature. On the whole the people must be pronounced to be extremely healthy--a fact probably due to their scrupulous cleanliness, to the excellent ventilation of their houses, and, as regards those living in the towns, to the wide and well-kept streets where nothing offensive is allowed to remain. The country has, however, from time to time been subject to epidemics introduced from without, cholera and the plague having more than once carried death throughout the length and breadth of the land.