Abstract: A generator for producing droplets of liquid by subjecting a confined body of such liquid to varying pressures at a given frequency and causing such liquid to issue from a discharge orifice first as a continuous stream and thereafter to break up into a succession of separate droplets. A particular use of the generator is to produce a controlled stream of ink droplets for the purpose of forming printed characters on documents. It accomplishes this object by making use of acoustic and ultransonic vibrations in a body of ink contained in a cavity of tapering dimensions having an ink intake passage and a discharge orifice, and causing periodic variations (or varicosities) in the hydraulic pressure at the discharge orifice which in turn causes the issuing stream of ink to break up into uniformly spaced apart fine droplets of ink.