1. The table of initial discharge coefficients of diaphragms should be corrected by taking the coefficient value 0.646 (instead of 0.645) for the 0.35 modulus. 2. The functional dependence of the initial discharge coefficient on the modulus of flow-contraction devices, represented by a polynomial of the 4th degree, yields deviations from the accepted values not exceeding 0.13%. 3. In order to compose interpolation tables, it is convenient to approximate the function α=f(m) for diaphragms by three polynomials, and that for nozzles by two polynomials, each corresponding to a certain given interval of moduli. The error in such approximation does not exceed 0.06% for diaphragms, and 0.05% for nozzles. The use of these equations secures uniform results in the interpolation of coefficients.