THE UNSTABLE EARTH

Dominion, Volume 7, Issue 2162, 30 May 1914, Page 6

THE UNSTABLE EARTH

CATCHING AN EARTHQUAKE ON THE WING.

ourmg to pifrgre&s of pjoutlily ■ ■meeting of tfas Philosophical Society the President fDr. Hector) announced that Messrs, Stewart and Dr.ll, two Victoria students, had made Bomo interesting respecting i-lio- earthfffaks. of February 8* ana", oao of them would report. ' Mr. Dail sail tliafc in the course of a Series of observations which involved tho very accurate measurement, of the distance between marks on two heavy ■.a yery 'interesting result was obtained. The pillars were sunk at. a distance of four chains apart, in the KTou'n.d to the north, of the fctsl- ■ lege buildings. Half of the observations wore ffiada on February i and tv and "half 011 February 9 and 10. A rather severe earthquake shock occurred on Sunday, February 8.. It was found, on comparing the results of tho two sets of observations mado before and after the earthquake that the measurements indicated a .permanent displacement of tho pillars relative to each other. The distattco between them vSaii'' decreased by .0367 cenii;n«tro (about ono-seventieth of an inch), with- a. probable, error in tho length of measure- / ment of .0033 or.dn«rtentl} oC.tho. dispteeement found. This ' displacement ■amounted to approximately 1-20?),000th part of His to.fri{ distance between tiio pillars. Professor Laby said tliat tho mcasuro consisted of brass* blocks set. in concrete pillars, and these had been erected by the Public Works Department for. testing stool tapes. It was not tlie. greatness or the differenoo that had been\ tested which made »tho obsorva- ■ t'ioft important, but that it should be so httlo after suoh a disturbance. / It was suggested to tho professor that had there occurred no variation at all tho observation would have been of still moro importance. "'Exa'ctlj so," said Profcss'or Labv, "after such a severe shock." .

Speaking more generally on earth, movement/; Mr. Thos. Humphries, lute-SBrvfeyor-G'ene'ral. stated that interesting variations -liatl 'oCGUrreil in ifew. Plymouth.. Tho line of Wife town had been voir carefully laid out by the. surveyors cr th<> Nor Zealand liah'J Company. in 1810 or Ifi-il. They had foi- ■ lowed what was railed tho "Devon liiie."; which sireicfied asftfv out into the country for Soino twelve miles. These who .know New' Plymouth worn aware' that the Post Office, v.'iis oh 0.110 : hi!i ( and tho centre of, tho town was in n hollow, where, the Tluitqlri Strf-a.ni flowed, ur.d Liardet Street intersected tlio main street (Devon Street) ftn t-ho opftosiio hill. It- had heen found tlmt betweenlßll and 1-870 tho o^r.tro 1 of tHie line which was clearly marked with a standard had moved 'tliree feet, seaward, and looking from ojio lri!"l to tho other quito a bulgo was percept- : ilifo in the centre. Ho did not know if that movement. Tiad' been caused bv the earthquakes of IK6S, hut was rjiiilier illcliiiod to believe that tho earth had slipped over its papa foundation. ■