To carry out investigations in the region of the remote ultraviolet radiation of the Sun outside the atmosphere we developed a two-channel diffraction spectrometer. In carrying out its construction the following requirements and considerations were borne in mind. 1. The absence of any materials, which are transparent for the greater part of the remote ultraviolet, makes it impossible to use filters and compels us to use a concave diffraction grating for the spectral expansion. With this it is necessary to employ as photoreceivers secondary electronic multipliers (VEU) of an open type. 2. It is necessary to carry out measurements by means of comparison with some standard radiation (in an energy sense). It is very advisable to use for this purpose continuous solar radiation, which is well known and constant as regards time, in the interval of wavelength 1700-2000 A. 3. For selecting the emission line to be examined in the presence of the background we may use a scanning of the spectrum on a small part around this line. 4. The illumination of the aperture of the instrument by the Sun’s radiation is carried out with the help of a following system. It is advisable to reject the idea of guiding the whole spectrometer, since this requires a considerable expenditure of energy, and to follow the Sun with a light mirror, made from melted quartz and covered with a fine film of thorium dioxide. This permits us to reduce the necessary means of supply but at the same time it brings about some additional loss of light. 5. The electronic recording part of the instrument must work both with the weakest and also with the strongest light flows. This requirement issues from the following considerations. The intensities of the measured lines are known very approximately and their magnitudes may fluctuate within rather wide limits. Thus, for example, the data of various authors(1-4) about the intensity of the line 1303.8 A differ by almost ten times, and for the measurement of its magnitude with an accuracy of ten per cent the system must measure light currents in a span reaching three orders. In addition, the change in the coefficient of reflection of the following mirror with the change of the angle of incidence and the low accuracy of determination of the effectiveness of the optical elements of the instrument in the region of the spectrum which is being investigated may lead to a difference between the light flux, falling on the photo receiver, and that calculated by as much as ten times. Also we cannot rule out the possibility of measurement of the sensitivity of the photoreceiver itself together with its electronic circuit . All this leads to the necessity of making a recording scheme, by the method of making measurements in the range not less than lo5 with maximum value of the flux 10 erg/cm2 x se& for all emission lines. Finally, it is necessary to have in view the investigation of changes in emission with time, which, for example, for a solar outburst may lead to fluctuations of current ten to a hundred times as much.