Variations in rotation of the earth, results obtained with the dual-rate moon camera and photographic zenith tubes

1959 ◽  
Vol 11 ◽  
pp. 26-33
Author(s):  
Wm. Markowitz
Keyword(s):  
Seasonal Variation ◽  
Research Laboratory ◽  
Quartz Crystal ◽  
National Physical Laboratory ◽  
Naval Research ◽  
Love Number ◽  
The Earth ◽  
Physical Laboratory ◽  
Rotation Of The Earth ◽  
Irregular Variation

Comparison of photographic zenith tube (P.Z.T.) observations with time derived from quartz-crystal clocks during 1951 to 1955 and with cesium standards of frequency during 1955 to 1958 indicates that the seasonal variation is nearly the same from year to year. Lunar-tidal inequalities of semi-monthly and monthly periods with amplitudes of about 0S.001 each were found. A preliminary value of the Love number, k, is derived. Observations made since 1952 with the dual-rate moon position camera are used to derive ΔT = ET – UT. Comparison of the P.Z.T. observations and atomic standards at the National Physical Laboratory and the Naval Research Laboratory shows details of the irregular variation from 1955 to 1958.

Time and The Royal Society

2001 ◽  
Vol 55 (1) ◽  
pp. 9-27
Author(s):  
A. Cook
Keyword(s):  
Royal Society ◽  
Frequency Standard ◽  
National Physical Laboratory ◽  
The Sun ◽  
The Earth ◽  
Physical Laboratory ◽  
Astronomical Time ◽  
Rotation Of The Earth ◽  
Lord Kelvin ◽  
Atomic Time

Fellows of The Royal Society have been concerned with the definition and measurement of time from the first days of the Society. John Flamsteed, F.R.S., ‘Royal Astronomer’, showed that the rotation of the Earth was isochronous and that the length of the solar day varied with the season because the path of the Earth about the Sun was an ellipse inclined to the Equator of the Earth. In the 20th century, D.W. Dye, F.R.S., made quartz oscillators that replaced mechanical clocks, and L. Essen, F.R.S., brought into use at the National Physical Laboratory the first caesium beam frequency standard and advocated that atomic time should replace astronomical time as the standard. The Society supported the development of chronometers for use at sea to determine longitude, and Fellows used the electric telegraph to find longitude in India. Edmond Halley, F.R.S., estimated the age of the Earth from the saltiness of lakes and seas; Lord Kelvin, F.R.S., estimated the rate at which energy was being radiated from the Sun; and Lord Rutherford, F.R.S., showed how the ages of rocks and of the Earth could be found from decay of radioactive minerals in them.

James Dyson, 10 December 1914 - 22 January 1990

1991 ◽  
Vol 37 ◽  
pp. 150-174
Keyword(s):  
Binocular Vision ◽  
Research Laboratory ◽  
Scientific Work ◽  
National Physical Laboratory ◽  
Early Age ◽  
Great Satisfaction ◽  
Many Instruments ◽  
Physical Laboratory ◽  
Wrong Direction ◽  
The Many

James Dyson always reckoned that he had been a lucky person, actually paid to do just what he wanted to do, work in optics. He recalled that as a very small boy in his cot he had noticed that he could see through the slats of the cot, could see objects behind these slats (because, of course, of binocular vision); had been surprised to see images of passing vehicles - seen on the wall of his bedroom - apparently moving in the wrong direction; this was because a hole in the fan light acted as a pin-hole camera, and even at that age he worked out the reason for the strange movements. His father, a joiner and cabinet maker and artist with a strong flair for invention, had made a telescope for which he ground the mirrors; watching the telescope grow set ‘Jim’ firmly on the track of optical instrumentation, a track that he travelled fast and with distinction. His interest in the telescope led him to astronomy; at an early age he tried to calculate Jupiter’s orbit and thus became interested in mathematics, all his life he was never at a loss to calculate all he needed for the development of the many instruments he invented. In the Research Laboratory of the Associated Electrical Industries (AEI Ltd) he was in great demand, helping scientists in other disciplines to solve their problems by one or other of the instruments he devised, and in moving to the Optics Division of the National Physical Laboratory (NPL) he continued in the same vein. He was extremely happy in all his scientific work and gave great satisfaction to his colleagues by the cheerful way he helped them.

Conversaziones 1958

1958 ◽  
Vol 13 (2) ◽  
pp. 75-81
Keyword(s):  
Royal Society ◽  
Nuclear Power ◽  
National Physical Laboratory ◽  
Radio Emissions ◽  
Power Stations ◽  
Flexible Films ◽  
The Earth ◽  
Physical Laboratory ◽  
Accuracy Of Measurement ◽  
Topical Interest

Conversaziones were held this year on 15 May and 26 June, and in addition there was a further special conversazione on 15 July to celebrate the Darwin-Wallace centenary. An account of this special conversazione will be found on page 73. At the first conversazione, on 15 May, there were 27 exhibits and a film. An exhibit of much topical interest was that prepared by members of the Royal Society W orking Party on Radio Emissions from Earth Satellites, which showed how the tracks of the Russian earth satellites were plotted. The orbit of such a satellite is nearly, but not quite, fixed in space, and the earth rotates inside the orbit. Observations were made by both radio and radar, and much information about the ionosphere and upper atmosphere was obtained from the analysis of changes in the shape and position o f the satellites’ orbits. Dr J. C. Evans and Mr I. G. Morgan, Metrology Division, National Physical Laboratory, Teddington, exhibited a pneumatic instrument for accurately measuring the thickness of flexible films. Use of a pneumatic technique for this purpose has the advantage that the film is not compressed or in any way distorted while measurement of its thickness is being made, and results of an accuracy of the order of ± 10 micro-inches can be obtained. An exhibit on the properties of circular diffraction gratings was arranged by the Optical Section of the Research Laboratories of Associated Electrical Industries Ltd., Aldermaston. Particular emphasis was given to the ways in which such gratings may be used to measure straightness, which can be ascertained, by this means, to an accuracy of about in. per mile. Such minute accuracy of measurement has important technical applications, such as in the alignment of the bearings of the very large turbo-alternators now being built for nuclear power stations.

THE GRAVITY METER AS A GEODETIC INSTRUMENT

Geophysics ◽  
1950 ◽  
Vol 15 (1) ◽  
pp. 1-29 ◽  
Author(s):  
George Prior Woollard
Keyword(s):  
National Physical Laboratory ◽  
Base Stations ◽  
Absolute Gravity ◽  
Naval Research ◽  
Absolute Value ◽  
Office Of Naval Research ◽  
Physical Laboratory ◽  
The World ◽  
Before And After ◽  
The Absolute

A special Worden temperature compensated gravity meter having a range of 5,500 mgals, and a reading sensitivity of 0.1 mgal was used to tie together various primary gravity base stations around the world and to establish new stations. Air transport was used and in a 3 month period over 80,000 miles were flown. Thirty‐three pendulum stations were reoccupied involving a change in gravity of 3,800 mgals, and 125 gravity stations were established. The investigation demonstrated that this instrument could be used satisfactorily for long range geodetic work and the results appear to be the equal of good pendulum observations. Drift was corrected for on the basis of the drift rate established immediately before and after flights. Closures after correcting for drift averaged less than 0.4 mgals, and the closure for the world girdling loop was 0.33 mgals. The probable error based upon the gravity values at the reoccupied pendulum station was ±0.5 mgals. Reoccupation of the absolute gravity stations at the U. S. Bureau of Standards in Washington, D. C. and the National Physical Laboratory in Teddington, England, indicated an approximate 5 mgal error in these pendulum determinations. Indirect ties to the absolute gravity base in Potsdam, Germany, through the primary national gravity bases tied to it, indicated a 15 to 19 mgal error in the Potsdam absolute value. Most of the primary national gravity bases tied directly to Potsdam were found to agree among themselves to within 1 mgal, and the U. S. Bureau of Standards Absolute Base in Washington, D. C. to have a perfect connection within the limits of accuracy of the present measurements. This investigation was made under the auspices of the Office of Naval Research.

Progress in Laser Propagation in a Maritime Environment at the Naval Research Laboratory

2005 ◽  
Author(s):  
G. C. Gilbreath ◽  
W. S. Rabinovich ◽  
C. I. Moore ◽  
H. R. Burris ◽  
R. Mahon ◽  
...  
Keyword(s):  
Research Laboratory ◽  
Naval Research Laboratory ◽  
Naval Research ◽  
Laser Propagation ◽  
Maritime Environment

scholarly journals 75th Foundation Day of CSIR-National Physical Laboratory: Celebration of Achievements in Metrology for National Growth

MAPAN ◽  
2021 ◽  
Author(s):  
Sanjay Yadav ◽  
Goutam Mandal ◽  
V. K. Jaiswal ◽  
D. D. Shivagan ◽  
D. K. Aswal
Keyword(s):  
National Physical Laboratory ◽  
Physical Laboratory ◽  
National Growth
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