View source for Vertical Pendulum Tilt Meter

From Bidston Observatory

← Vertical Pendulum Tilt Meter

You do not have permission to edit this page, for the following reason:

---

You can view and copy the source of this page.

"The Observatory’s two levels of cellars and other features made it especially suited for calibrating chronometers under controlled conditions of temperature and seismic vibrations."<ref name="stephen">Stephen Pickles, A brief history of Bidston Observatory, 2016 http://www.bidstonobservatory.org.uk/a-brief-history-of-bidston-observatory/</ref> "[A] new activity commenced in '''1897''' with the installation in the cellars of a seismograph. This was the first of a series of seismographs of different designs that followed."<ref name="baker">Bidston Observatory: Earth Tides and Ocean Tide Loading, Trevor F. Baker, 2 November 2016 http://www.bidstonobservatory.org.uk/earth-tides/</ref> Reading and changing the seismographic records was part of the daily routine in Bidston Observatory.<ref>Joyce Scoffield, ''Bidston Observatory, The Place and the People''. p172</ref> "In '''1900''' Bidston obtained its own <u>Milne-Seismograph</u>. and tables of its observations were published from '''1901'''." <ref>Joyce Scoffield, ''Bidston Observatory, The Place and the People''. p149</ref> "The Dock Board felt that 'meteorological observations could be taken with equal accuracy elsewhere' and the Dock Board's 'interest in the unfelt tremors of the earth was not immediate'."<ref>Joyce Scoffield, ''Bidston Observatory, The Place and the People''. p150</ref> [[File:Milne.jpg|thumb|none|Tone Harikaw with her husband, seismologist Prince Boris Galitzin and John Milne (center) in 1910.]] "In '''1910''', observations were made <u>using instruments designed by Sir George Darwin, Sir Horace Darwin and others</u> to determine the yielding of the land to the load of tidal water, now called the ‘ocean loading effect’."<ref name="baker"></ref> ''Could this be the <u>Prof J. A. Ewing’s Seismograph</u> produced by Horace Darwin?''<ref>https://www.christs.cam.ac.uk/horace-darwin-1851-1928</ref> "As a result of the successful tests with the <u>Claustral Pendulum</u>, Bidston acquired a <u>Graf-Askania vertical pendulum</u> of its own, and installed it after modification." <ref>Joyce Scoffield, ''Bidston Observatory, The Place and the People''. p328</ref> Claustral Pendulum = encased pendulum? A 'Graf-Askania vertical pendulum' or 'gravimeter' or 'Askania vertical pendulum tiltmeter' measures tilt through changes in gravity (which is linked to measuring tidal load but I do not understand yet how). "New tidal tilt observations were made in the Bidston cellar in the '''1930s'''. Doodson and Corkan ('''1934''') used a <u>Milne-Shaw seismometer</u> for one month of observations. In '''1934''', funds were used from a Cambridge mathematics prize that was awarded to Proudman to purchase a <u>new Milne-Shaw seismometer</u>. Beginning in March '''1935''', one year of observations of the north-south tilt were made using this instrument (Corkan, 1939)."<ref name="baker"></ref> "Geoff Lennon made further observations of the north-south tilt at Bidston using the <u>Milne-Shaw seismometer</u> between '''1952''' and '''1954'''. For the International Geophysical Year 1957-1958 there were increased efforts to make observations of Earth tides around the world."<ref name="baker"></ref> "In the Bidston cellar, <u>modified Milne-Shaw seismometers</u> were used to measure the tilts in both the north-south and east-west directions from July '''1957''' to December '''1958''' (Lennon, 1959)."<ref name="baker"></ref> "The Bidston cellar provided a useful test site for comparing various tiltmeters, before installation in the tunnel at Llanrwst."<ref name="baker"></ref> [[File:Glasses.jpg|thumb|none|Photograph of a scientist with tiltmeter in situ, installed in the cellar of BOAC (2021)]] [[File:Milne-Shaw.gif|thumb|none|A Milne–Shaw seismograph in use at 'the Honolulu station' in Hawaii. (b) is the same instrument as shown in (a), but with the cover on. [https://prd-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/full_width/public/thumbnails/image/Preserving%20Historic%20Earthquake%20Records-%206.gif USGS]]] [[File:Plinth.jpg|thumb|none|Bedrock connection plinth (current situation, BOAC, 2021)]] [[File:North.jpg|thumb|none|The plinth on which the tiltmeter was installed, is oriented on the North-South axis (2021)]] ''The Milne-Shaw Tilt Meter (or maybe there was more than one?) was transferred to the University of Aberdeen in '''1997'''''. "The NSA (National Seismographic Archive) holds the <u>ex-Bidston Milne-Shaws</u>, examples of modern Willmore instruments, and probably the only Jaggar shockrecorder in existence."<ref>''Historical Seismological Observatories in the British Isles'', British Geological Survey, 1999 http://www.earthquakes.bgs.ac.uk/hazard/pdf/wl9913.pdf</ref> [[category: Instruments]] [[category: Stories]]

Return to Vertical Pendulum Tilt Meter.