k = 0 of which each term is larger than each term of defies (4). The latter, however, converges absolutely, since undex the summation sign we have a 8essel function of imaginary argument (Idx)). Therefore, series (4) converges even more rapidly, which was to be proved. Let q(z, r), an arbitraxy analytic function of its own coordinates, be the assigned value of temperatuxe on the lateral surface of the cylinder r = b (x = 1). We define the function S from (4) in the form of a series,