A little piece of history has been placed up for auction recently. It is a letter from Alexander Graham Bell to his father, with a drawing of his plans for the telephone.
Bell writes in the letter, postmarked from Washington DC, on December 30, to his parents that he is â€˜quite troubled by your account of the lightning accident at Tutelo Heights. The accident shows that the earth terminals of your telephone line are defective for the current found a shorter path to the ground through two of your poles than by the proper path'.
And he goes on to draw a remarkable diagram - two telephones - showing the correct mechanical assemblage to ensure proper function and, above all, safety.