 Even in the late 19th century , the islanders could communicate with the rest of the world only by lighting a bonfire on the summit of Conachair and hoping a passing ship might see it , or by using the " St Kilda <unk> " . This was the invention of John Sands , who visited in 1877 . During his stay , a shipwreck left nine Austrian sailors marooned there , and by February supplies were running low . Sands attached a message to a <unk> salvaged from the Peti <unk> and threw it into the sea . Nine days later it was picked up in Birsay , Orkney , and a rescue was arranged . The St Kildans , building on this idea , would fashion a piece of wood into the shape of a boat , attach it to a bladder made of sheepskin , and place in it a small bottle or tin containing a message . Launched when the wind came from the north @-@ west , two @-@ thirds of the messages were later found on the west coast of Scotland or , less conveniently , in Norway . 
