Abstract: A radiography apparatus comprises a radiation source which is arranged to supply radiation spectra of different energies. The apparatus also comprises a detector which can be adjusted for the radiation spectra so that a strong wavelength discrimination occurs in the measurement signals. In a detector comprising an ionization chamber, there is arranged an auxiliary electrode which can be adjusted in phase with the radiation source so that soft radiation of a soft source spectrum or hard radiation of a hard source spectrum is comparatively favored with respect to its contribution to the measurement signal.

Abstract: Remotely controlled electric printer, to which each character to be printed is applied as m groups of n bits, comprising a set of n rulers or print bars, the total thickness of which is equal to the height of said character or a line thereof, each character having a width of m bits. Electromagnetic means are provided capable of shifting the print bars transversely with respect to one another, and there is a cross bridge or anvil that can be moved along said bars. Paper or some other printing carrier is provided between the cross bridge anvil and the bars. The electromagnetic means are so arranged that they can shift the rulers or bars transversely with respect to one another in accordance with the n-bit groups so that the rulers thereby strike the paper against the cross bridge anvil.This anvil is stepped along the line in m equal steps for each character by a pawl and rack mechanism which also is operated electromagnetically by a separate electromagnetic means.