To warn ships of their presence in a dense fog, the Cromartyshire used a Norwegian Pattern Foghorn:
Norwegian Pattern Foghorn
A sailor on watch carried the valise size box to the bow, cranked several times until a loud mournful sound penetrated the mist.
To hear what the crew of both the Cromartyshire and La Bourgogne actually heard at 4:56 a.m. on 4 July 1898 click here