An analysis is presented of the characteristics of a magnetometer which uses an amorphous-metal ribbon as its primary sensing element and which operates by modulating the magnetostrictive strain. Magnetic fields at the second harmonic of the modulation frequency are identified as capable of significantly degrading the magnetometer performance. A second-harmonic field is measured and its contribution to the noise is estimated.

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Selection of co-belonging fragments from the numerous ceramic findings of an archaeological excavation remains a difficult process of questionable effectiveness, based exclusively on the experience and patience of the conservators. While the screening of the fragments is a central prerequisite and the most important stage of the process of vase reconstruction, established methods based on scientific criteria and guaranteed efficiency for the detection of co-belonging ceramic fragments suggested in the bibliography, do not exist. On the contrary, for methods dealing with the assembly of vases from co-belonging fragments, which is a secondary process that can be done more easily and effectively in an empirical way, there exist numerous studies based on fragment morphology. However, even these are also not implemented because of the time requirements, sheer volume and complexity of the proposed methods, in order for them to be applicable in practice. The proposed methods in this paper are based on thermoremanent magnetization (A/m), which is calculated from the weak magnetic field measurements by a fluxgate-sensor/magnet apparatus forming a three-dimensional orthogonal system. Experimental measurements from fragments of 6 vases show that the magnetization magnitude of co-belonging fragments display similar values, despite the magnetic anisotropy of the ceramic material, since these belong to vases that are made of the same clay and fired under the same conditions. This is the criterion for finding ceramic fragments of the same vase from archaeological excavations. The thermoremanent magnetism directionality of fragments, which is aligned along the geomagnetic field at the same place and time during the vase firing process, as it is configured by their rotational symmetry, defines the position of the fragments on the body of the 6 vases. The shape of the original vase can be reconstructed when only a few non adjacent fragments are available. The proposed measurement apparatus can be used for the construction of a useable portable magnetometer specialized for ceramic surface measurements to achieve the above objectives.

The directional total emittance E' of coated float glass (fluorindoped tin oxide coating 300 nm thick) and uncoated float glass was measured at 283 K and in the angular range 10" to 84". The direct method was employed in which the radiation emitted by the sample was measured using a broad-band Golay detector. A novel scheme of discriminating against unwanted radiation allows fractional uncertainties of f 1% or better (1 s.d.) to be achieved. The uncoated glass, the directional total emittance of which can be calculated accurately, was used to test the apparatus, and the difference between the measured and the calculated values waa found to be not greater than f 1%, fractional, for angles less than €40". * * *We are grateful to P. G. T. OWENS of Pilkington Glass Limited, UK, for providing the coated-glass sample and its spectral reflectance data, and also for his interest in our work. We also acknowledge F. J. J. CLARKE of the National Physical Laboratory UK, who obtained the spectral reflectance of our reference, and are grateful for his valuable help.