摘要:

Measurement science has been one of the major interests of the NPL since the creation of the Laboratory in 1900. This article gives a historical review of NPL work on the establishment, maintenance and improvement of the basic standards of measurement for mechanics, electro-magnetics, thermometry, photometry and radiology. Many early NPL standards and essential components of classioal measuring equipment have now been assembled into a permanent collection for preservation at the Laboratory and illustrations of some items in this collection are reproduced in the article.

ISSN:0010-7514    

DOI:10.1080/00107516808204397

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A new determination of the constant of gravitation is being prepared, more than 30 years after the previous one. The reasons for undertaking a new determination are outlined and the methods that have been adopted in the past are reviewed. The design of the new determination, which incorporates a number of refinements of principle and execution, is discussed.

ISSN:0010-7514    

DOI:10.1080/00107516808204398

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The rotation of the plane of linearly polarized light by an optically-active medium arises from a difference between the refractive indices of the medium for left- and right-circularly polarized light. The circular birefringence is related to a circular dichroism, which is exhibited by all molecules which are not superposable on their mirror image and exist as laevo- and dextro-rotatory isomers. The circular dichroism of a dissymmetric molecule in a particular absorption region originates from an electronic transition with collinear electric and magnetic dipole moments, corresponding to the displacement of a molecular valency electron through a helical path by the absorption of radiation. The right- or left-handed form of the helical path depends upon the molecular structure, and the absolute stereochemical configuration of dissymmetric molecules may be determined by comparing their circular dichroism spectra with the calculated rotational strengths. In addition the polarization direction of an electric moment and the magnitude of a magnetic moment of an electronic transition in a dissymmetric molecule may be derived from circular dichroism measurements.

ISSN:0010-7514    

DOI:10.1080/00107516808204399

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

For almost a hundred years the diffraction grating has been among the most important of scientific tools. The methods of ruling gratings for use in all regions of the spectrum from the soft x-ray region to the infra-red are described. The properties of ideal and imperfect gratings are considered and an account of present-day scientific and industrial uses is given.

ISSN:0010-7514    

DOI:10.1080/00107516808204400

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The first part considers the theory of the liquid state, discusses the influence of quantum effects on liquid beheviour, and introduces the dimensionless quantum parameterA* which expresses their relative importance. The second part surveys the experimental results for the chief physical properties of liquid rare gases (and also of liquid methane). The observed quantities have been ‘reduced’ for comparison purposes to dimensionless numbers, each being divided by an appropriate parameter of its own dimensions.

ISSN:0010-7514    

DOI:10.1080/00107516808204401

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Field Theoretical Methods in Many Body Systems. By D. P. Kirzhnits. Translated by A. J. Meadows and edited by D. M Bruck. (Pergamon Press, 1967.) [Pp. Wi+394.] £5 10s.

ISSN:0010-7514    

DOI:10.1080/00107516808204402

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107516808204403

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor