312 



THE POPULAR SCIENCE MONTHLY. 



quite overturned, as appears to have happened to the stud-mill at Hay- 

 ward, California (Fig. 8). 



In any building which may be affected by an earthquake, we have 

 to consider the vibration of a number of parts, the periods of which, 

 if they were independent of each other, would be different. On ac- 

 count of this difference in period, while one portion of a building is 



Fig. 6. Chtjbch of St. Aitgustin, Manila. Earthquakes op July 18-20, 1880. 



endeavoring to move toward the right, another is pulling toward the 

 left, and either the bonds which join them or the parts themselves will 

 be strained or broken. This was illustrated by many of the chimneys 

 in the houses at Yokohama, which, in the earthquake of February 20, 

 1880, were shorn off just above the roof. Since then, builders have 

 learned to let chimneys pass freely through the roof without coming 

 in contact with any of the main timbers. 



In trying to make structures earthquake-proof, we may build our 

 house weak and flexible, so that the shock shall pass over it as the 

 wind over a reed, or we may attempt to make it stronger than the 

 shock. The native Japanese houses, with their flexible framing, are 

 built on the former plan ; some of the European houses essay the 



