For large structures in which wood cannot be used, strongly reënforced concrete is well adapted, for it has in general the same advantages as steel with somewhat reduced elasticity, but with a more effective binding together of the parts. This requirement of thorough bracing and tying together of the several parts of a building causes it to vibrate, not as many pendulums, but as one body. If met, it removes largely the danger from racking strains, and for small structures particularly it is the requirement which is most easily complied with. For such buildings it is therefore necessary that the framework should be built in a close network with every joint firmly braced and with all parts securely tied together. Especial attention should be given to the fastenings of floor and partition ends. The house shown in Fig. 85 could not have been subjected to heavy shocks, for though the walls are thrown down, the floors and partitions have been left near their original positions. [Illustration: FIG. 86.—Building wrecked at San Mateo, California, during the late earthquake. The heavy roof and upper floor, acting as a unit, have battered down the upper walls (after J. C. Branner).] This tendency of the walls, floors, partitions, and roof to act as individual units in the vibration, is one that must be reckoned with and be met by specially effective bracing and tying at the junctions. Otherwise these larger parts of the structure may act like battering rams to throw over the walls or portions of them (Fig. 86). READING REFERENCES FOR CHAPTERS VII AND VIII General works:— JOHN MILNE. Seismology. London, 1898, pp. 320. C. E. DUTTON. Earthquakes in the Light of the New Seismology. Putnam, New York, 1904, pp. 314. A. SIEBERG. Handbuch der Erdbebenkunde. Braunschweig, 1904, pp. 362. COUNT F. DE MONTESSUS DE BALLORE. Les Tremblements de Terre, Géographie Séismologique. Paris, 1906, pp. 475; La Science Séismologique. Paris, 1907, pp. 579. WILLIAM HERBERT HOBBS. Earthquakes, an Introduction to Seismic Geology. Appleton, New York, 1907, pp. 336. C. G. KNOTT. The Physics of Earthquake Phenomena. Clarendon Press, Oxford, 1908, pp. 283. E. RUDOLPH. Ueber Submarine Erdbeben und Eruptionen, Beiträge zur Geophysik, vol. 1, 1887, pp. 133-365; vol. 2, 1895, pp. 537-666; vol. 3, 1898, pp. 273-536. Descriptive reports of some important earthquakes:— C. E. DUTTON. The Charleston Earthquake of August 31, 1886, 9th Ann. Rept. U. S. Geol. Surv., 1889, pp. 203-528. B. KOTÔ. On the Cause of the Great Earthquake in Central Japan, 1891, Jour. Coll. Sci. Imp. Univ., Tokyo, Japan, vol. 5, 1893, pp. 295-353, pls. 28-35. JOHN MILNE and W. K. BURTON. The Great Earthquake of Central Japan. 1891, pp. 10, pls. 30. R. D. OLDHAM. Report on the Great Earthquake of 12th June, 1897, Mem. Geol. Surv. India. Vol. 29, 1899, pp. 379, pls. 42.