A wonderful scientist, faded in the heyday of creative forces, Nicholas . Evgrafovich Kochin belongs to the Soviet era . His first work was published in 1923. Numerous studies by H. E. Kochin devoted to fundamental problems of theoretical meteorology, gas dynamics, hydromechanics of ideal liquid, wave theory, nonlinear oscillations of differential equations. His works are distinguished by the depth of analysis and clarity of mechanical representations; mathematical conclusions are carried out with exceptional strictness and completeness; if necessary, the solution is brought to numerical results. Classical works N. E. Cochin is a major contributor to Russian scientific literature. The first volume of the essays includes research by H. E. Kochin in the field of dynamic meteorology, in the second - works on hydrodynamics, aerodynamics and wave theory, in applied and theoretical mechanics and in mathematics.