Ernest Grosjean (1844 - 1936) published "Pièces pour orgue ou harmonium", a set of 56 pieces in two volumes, in 1902. The first volume contains 33 easy pieces, that can be played without the use of pedals. The Invocation is a modest lyrical piece, that can be beautifully coloured with slightly different registrations on two manuals. The give it an extra punch I double the bass notes in the middle section on the pedals.
Score available here: http://partitura.org/index.php/ernest-grosjean-invocation