This article reports an experimental investigation on the disintegration of cylindrical jets through a study of the stability curve. We are interested mainly in the behavior of low-velocity jets in order to understand the development of the critical point, the first maximum on the stability curve. The experimental results obtained for a jet of water under varying ambient pressures show that the critical point is not due to the effect of the aerodynamic forces for our working conditions. A detailed comparison. with other experimental measurements and with predictions deduced from models available in the literature is carried out and suggests a classification of the jet behavior according to the ratio rho(G)*/rho(G), where the critical density rho(G)* is a new jet parameter that is a function of the Ohnesorge number and of the length-to-diameter nozzle ratio. A new modification of Weber's equation is suggested here in order to predict the critical velocity in any situation. The Hew model, tested for the experimental situations studied in the present article, calculate critical velocity in good agreement with the experimental measurements.