112 



EAKTHQUAKES. 



Fig. 20. 



Fig. 21. 



zontal as to vertical movements. Such a wall is shown in 

 fig. 20 : the dotted lines running through the openings, and 

 all similar lines parallel to the former, representing lines 



of weakness. If we 

 compare this with fig. 

 2 1 , we shall see that in 

 the case of a horizontal 

 movement ah or of a 

 vertical movement c d, 

 we should rather ex- 

 pect to find fractures 

 in a house built like 

 fig. 21 than in one 

 built like fig. 20. If, 

 however, these two buildings were shaken by a shock 

 which had an angle of emergence of about 45° in the 

 direction ef, the effects might be reversed. Usually, 

 however, and always in a town like Tokio which is visited 

 by shocks originating at a distance, the movements are 

 practically horizontal ones, and, therefore, buildings 

 erected on the principles illustrated by fig. 20 should be 

 much superior, so far as resisting earthquakes is concerned, 

 to buildings constructed in the ordinary manner, as in 

 fig. 21. Fractures following a vertical line of weakness are 

 show^n in the accompanying drawing, fig. 22, of the Church 

 of St. Augustin, at Manilla, shattered by the earthquakes 

 of 1880. 



The last House in a Row. — When an earthquake shock 

 enters a line of buildings, and proceeds in a direction 

 coincident with that of the buildings, we should expect 

 that the last of these houses, being unsupported on one 

 side, would be in the position of the last person in Tyndall's 

 row of boys. From this it would seem that the end house 

 in a row would show the greatest tendency to fly away 

 from its neighbours. If the last house stood upon the 



