It- 



I 



248 



llErOKT- 



884. 



quake came the smoked surface on wliicli the recoi'd ought to have been 

 written had been removed. 



Although I varied the adjustments of the iustvumeut in a variety of 

 manners, I was unable to destroy this tendency to wander. The only 

 cxplaniition which I can offer of the phenomena, is that it is either due to 

 a settlement taking place in the column, which from the nature of the 

 motion is unlikely, or that it was due to actual chauges in the level of the 

 soil. 



Ah final resort the point of suspension of the conicnl pendulums was 

 brought sufficiently forwards to give them a definitely stable position, 

 since which all earthquakes which have occurred have been successfully 

 recorded. Although I have in this manner destroyed the sensibility of 

 the instrument, I mny remark that it is sufficiently sensitive to give a 

 daily u:cord of the tiring of a time gun, situated mf)re than 100 ^-ards 

 distant. Tiie intervening ground is hard and full of excavations. 



Hitherto, I have not had time to analyse the various records which 

 have been obtained, and am therefore compelled for the present to reserve 

 any report npon them. Mr. Gray is, I am pleased to say. constructing 

 two new seismographs. These are so ai'ranged that they will record, 

 either slow tips in tliu soil or earthquakes, the diagiwus being nuide with 

 ink on a strip of paper. 



Fapcrimcnis on a Bnildiinj io rr.<!!<l I'JartlKpiake iiiolion. 



I have previously drawn attention to the great difference in the 

 effects which moderately strong earthquakes have producetl upon 

 European and on Japanese types of buildings, the former being more or 

 less shattered whilst the latter escape without any apparent damage, lu 

 the one case we have a building of brick and mortar firndy attached by 

 its foundations to the shaking earth, whilst in the other we have a light 

 wooden structure resting loosely on boulders. If the former is of a type 

 fur which patents have been granted, where iron hoops and tie rods 

 together with all the devices which give strength and solidity have been 

 employed, it certainly resists the eff'ects of disturbances which have , 

 shattered buildings of ordinary construction. An important objection 

 to dwellings of this order is their great expense. 



With the above considerations before one, and with a knowledge that, 

 the chief motion in the majority of earthquakes in this country is the 

 horizontal component, I have erected for experimental jjurposes a small 

 building resting on four cast-iron balls. 



The building, which measures 20 feet by II' feci, is constructed of 

 timber with a suingle roof, plaster walls and ceiling of laths and paper. 

 The balls rest on cast-ii-on plates with sancer-liko edges tixed on tho 

 heads of piles. Above the balls and attached to the building are cast- 

 iron plates, slightly concave but otherwise similar to those below. From 

 the records of instruments placed in the building, it would appear that at 

 the time of the earthquake there is a dow back and forth motion, bnt 

 that all the sndih'ii motion or fhorli has been destroyed. Thus far the 

 building or rather its foundations have proved successful in eliminating 

 the destriujtive element of motion. 



I am now exporimenting on the foundations by using flat phttes, and 

 by giving such frictional resistances to movement that the buildiii'^' may 

 become astatic. If this is successful, as I trust it will be, although devices 



