H.B. SELBY & CO., SCIENTIFIC APPARATUS & LABORATORY EQUIPMENT
his advertising cover for H.B. Selby & Co. at 393 Swanston St., Melbourne has the blue 3d Submarine Telephone Communication to Tasmania stamp postmarked with a roller cancel dated 25 May 38 and is addressed to Difco Laboratory, a Michigan-based manufacturer of microbiology media and supplies in Detroit, USA. The reverse shows a figure of an aneroid barometer (Figure 1). This cover intrigued me, as the Selby company was well