146 



NATURE 



[November ;o. nn i 



other appreciably until their distance apart is less than 

 ()'8 of their length, and that this influence is becoming 

 very noticeable when the distance apart is o'6 of their 

 length. It was also found that, with the models in any 

 given position, the forces involved varied as the resist- 

 ance of the models, i.e. for these speeds roughly with 

 the square of the velocity as theory would lead us to 

 expect. 



The variations of the forces as one model was 

 moved to varying fore and aft positions relative to the 

 other (keeping the lateral distance the same) showed 

 the very strong tendency which any model had to cant 

 into the stern of the other model which it was over- 

 taking, how this tendency to cant changed, as the 

 models were brought abreast each other, to a strong 

 sheer of each model towards the other, and, finally, 

 when one model was shifted so that its bow was 

 well forward of the bow of the other, it had a strong 

 desire to cant away from the latter. This is all much 

 the same as the consideration of our two ovals has 

 led us to expect, and goes to show that passing vessels, 

 even in deep water, arc liable to exert strong forces 

 upon each other. If they are moving at approximately 

 equal speeds in the same direction, i.e. if the forces 

 are maintained for a considerable time, then these 

 forces will tend to produce erratic movements of the 

 ships, requiring careful navigation if a collision is to 

 be avoided. 



No experiments have been made up to the present 

 to test this suction or interference in shallow water, 

 except those made recently at the National Experiment 

 Tank at Teddington in connection with the Hawke 

 and Olympic collision ; but the general reasoning- 

 already given is good ground for supoosing^ that such 

 influence would be preatly matrnified as a vessel 

 passed from deep to shallow water. 



THE CENTRAL EUROPE EARTHQUAKE. 

 NOVEMBER 16, 1911. 



ON the night of November 16, at 10.25, western 

 Germany, eastern France, and Switzerland were 

 rudely shaken bv an earthquake of exceptional in- 



eurthquake was marked by ii^... .iwu. ..L.^u. .,u*j4 ... 

 Berlin. Everywhere terror-stricken people "rushed" 

 from their houses, and at Ebingen 500 of its inhabi- 

 tants gathered round a fire during the night and 

 recounted their weird experiences. 



It is difficult to reconcile these descriptions of wide- 

 spread ruin with the fact that there does not appear 

 to have been a single casualty. One thing about 

 which we can be certain is that the earthquake was 

 felt eastward to Erfurth, westwards to Nancy, and 

 southwards to Milan. At least 17,000 square miles 

 of Central Europe received a shaking perceptible 

 the greater number of its inhabitants. Outside t 

 area it was recorded by many seismographs. Wheti 

 the disturbance was or was not recorded in very c 

 tant places largely depends upon the character of • 

 instrument employed to record teleseismic moti' 

 Experience has shown that seismographs recording; 

 photographically pick up these effects at greater dis- 

 tances from an epicentral area than those whi' '■ 

 register mechanically. 



The accompanying seismogram of east and v.' 

 motion, as recorded in the Isle of Wight, shows ti 

 the disturbance commenced at gh. 27m. 30s., ;i 

 reached a maximum two minutes later. The inf 

 ence from this is that the origin was 5 degrees or 3 

 geographical miles distant. That it was a near earth- 

 quake is also indicated by the rapidity of the vibm- 

 tions. At the distance indicated we reach the up; 

 part of the Rhine Valley, a district from Frankfi 

 through Bale to Constance, well known to s- 

 mologists as an earthquake-producing region. Ii 

 popular sense the upper part of this is a valley, ' 

 from the manner in which it originated it is sometin 

 referred to by geologists as a graben, or piece 

 territory that has fallen downwards between t 

 faults. In this instance one of these faults bord. ; - 

 the Vosges and the other the Black Forest. It is .. 

 tectonic displacement along which adjustments fr' ■ 

 time to time have taken place, each of which rej ; 

 sented a relief of strain and was accompanied h\ 

 shaking. One well-known paper solemnly informs 

 readers that this earthquake was of Teutonic nriL. . 



"SrlT 



v^'w.vw;wMv>' 



ten?iiy. At Frankfort-on-Main houses were cracked. 

 In Freiburg, Stuttgart, Munich, Miilhausen, and in 

 other towns, chimneys and roofs were damaged. The 

 valley of the Upper Rhine was shaken throughout its 

 length. At Constance two colossal statues fell from 

 the Post Office upon the pavement. According to 

 reports in the daily papers, walls were split, church 

 spires were wrecked, roofs were shattered, people w-ere 

 "thrown out of their beds," telephone and telegraph 

 communications were destroyed, and the path of the 



NO. 2196, VOL. 88] 



and, considering the country in which it was made, t 

 statement may be regarded as correct. 



At present it cannot be said with certainty that tl 

 disturbance originated from the chief of these tectoi 

 lines or from one of their numerous offshoots. 1 

 the right and the left of the Rhine Valley the count: 

 is cracked through and through with many mir 

 fractures, a sudden movement on any one of whi 

 might be capable of producing all that has be 

 observed. J. Milne. 



