wooden construction, 347. There were in addition, 309 small bridges, most of them wooden, which were classified as private bridges.

Of the 583 city bridges, 69 were shaken down by the earthquake shocks and 289 were destroyed by the ensuing fire. The destruction of these bridges seriously hindered communication and transportation at a most critical time and seriously impeded the rescue of those trapped by the flames. Many of the steel bridges had wooden floors;

Kiyosu-Bashi, a suspension bridge across the Sumida River, has a central span of 300 feet. The suspension system consists of manganese-steel eyebars, and the bridge rests on pneumatic caissons. The completed structure will cost 2,500,000 yen.

this proved to be a fatal defect, causing the destruction of bridges which would otherwise have remained undamaged.

As a result of the lessons learned through the calamity the bridgebuilding program was realized to be a vital part of reconstruction work and an essential to any system providing for safety during similar emergencies in the future. The first consideration in bridge design was obviously that of safety against fire and earthquake damage; the second was that of esthetic appearance, in view of the efforts being made to create in Tokyo a model imperial capital.

This two-hinged arch bridge with 167-foot spans and a total length of 507 feet will be completed during the present year. The total construction cost is 1,600,000 yen. Two-hinged arch bridges showed great resistance to earthquake shocks and are considered very satisfactory for this district.

Hijiri Bridge is an imposing reinforced-concrete arch spanning a canal. It has a total length of 93 meters and a width of 22 meters. The street shown is one located and built since the earthquake. The large building in the right background is the Russian cathedral, partially destroyed in the earthquake of 1923.

This structure, one of the most noteworthy of the present bridges across the Sumida River, has a central span of 330 feet, a total length of 600 feet, and a width of more than 72 feet. It is an arch bridge with suspended roadway. Horizontal reactions are cared for by tie-rods at the bottom. The bridge has cantilever side spans and stands on pneumatic caissons, the deepest of which is nearly 90 feet below low water. The structure contains 4,000 tons of steel and cost 2,800,000 yen. It has a considerable factor of safety against earthquake forces. An American engineering firm rendered notable service in its supervision of the construction of the caissons and piers.

Of the entire program of 117 bridges to be built by the Reconstruction Bureau in the city of Tokyo, including the 6 bridges over the Sumida River, 37 have been completed, 30 are under construction, and 39 have been completely designed; thus the bridge program is estimated to be 60 per cent complete. Of the estimated expenditure of 32,000,000 yen, 20,000,000 yen has already been expended. The percentage of completion and the amounts of money shown as expenditure for street construction include bridge-construction costs and percentage of completion. Of the 34 bridges being constructed in the city of Yokohama by the Reconstruction Bureau, 14 have been completed, 13 are under construction, and 5 others are completely designed. Figures 22 and 23 give some details of interest in connection with the various structures.

It is of interest to note that in some construction American equipment has been used. An American locomotive crane was used on one structure; compressors and pneumatic riveters are almost entirely of American make; about 80 per cent of the concrete mixers are also of American make. In general it may be said that concrete mixers of Japanese manufacture are used in the smaller sizes up to about 8 cubic feet capacity, and American mixers are used for greater capacities. As the 8-cubic-foot size is in greatest demand, Japanese manufacturers make a considerable number of these, but even in this size there is a great demand for American mixers. This is due in considerable measure to the fact that operators and contractors have become accustomed to using American mixers and are acquainted with their efficiency and results, and some insist on them in preference to other makes.

It is also interesting to note that a considerable amount of American steel-sheet piling was used in the construction of these bridges. Competition is extremely keen between American sheet piling and the less efficient, lighter, and cheaper European steel-sheet piling. It is often impossible to remove and redrive European steel-sheet piling, while with the heavier American forms this is generally done.

In connection with pneumatic caissons and piers for three of the largest of these bridges, it may be worthy of remark that an American engineering firm was retained to cooperate with the Japanese authorities and did notable work.

PARKS

Parks are considered an important element in aiding cities against loss of life from the fires which inevitably follow severe earthquakes. They are essential as places of refuge and are very useful in impeding the progress of sweeping conflagrations. Moreover, their value in any city under normal conditions as places of beauty, as recreation centers, and as open spaces contributing generally to the health and enjoyment of the populace, is fully realized by the Japanese.

The area of parks in Tokyo before the earthquake of 1923 was 750,000 tsubo (625 acres). The new program calls for additional parks of an aggregate area of 110,000 tsubo (90 acres). Three parks of some extent will be provided by the Reconstruction Bureau and 50 small ones will be provided by the city.

The construction of the 50 small parks by the city of Tokyo is a special feature of the city's reconstruction scheme. The authorities desired to have a park or playground in the immediate vicinity of each of the 117 primary schools in the destroyed districts of Tokyo.