Advance franking seal of office "Imperial Director of post office German East Africa" (Morogoro), two-line cancel "franked / with 7 1/2 H. " violet, with railway mail "midland train ZUG 20 b 29.4.16" to Dar es Salaam with arrival postmark, rare Indian cover, vertical archive fold, at the bottom opened, expertized Bothe and Jäschke-Lantelme BPP