The first order vectorial operator 'curl' occurs in many areas of applications, e.g. in electrodynamics, fluid mechanics (hydrodynamics), magnetohydrodynamics and elasticity theory. It is the purpose of this note to discuss a particular instance of 'curl' where a domain can be given to 'curl' so that it becomes a selfadjoint operator. The particular domain of selfadjointness under consideration is singled out by its relevance in applications. To establish this operator we initially consider 'curl' as an operator curl| •