“ Sixteen machines with alleged diagnostic and curative capabilities had been shipped in interstate commerce. Leaflets describing the uses of the machine had been shipped at a separate time. The Court of Appeals, 164 F.2d 245, had held that the separate shipments of the machines a d leaflets precluded a conclusion that the leaflets had accompanied the device in interstate commerce, and therefore the transaction was outside the reach of the Act. We reversed the Court of Appeals and held that the separate shipment of the machines and leaflets constituted a single interrelated activity. ”