Telegraphy is a technique of sending textual messages upto long distances by using symbolic codes. It was helpful in military operations. The technology was invented during 1820s. But interestingly, this technology has been discussed in our Vedas which were written in Vedic times during (1500-1000 BCE).
RigVeda 1.119.10
RigVeda 1.119.10
युवं पेदवे पुरुवारमश्विना स्पृधां श्वेतं तरुतारं दुवस्यथः Ι
शर्यैरभिद्युं पृतनासु दुष्टरं चर्कृत्यमिन्द्रमिव चर्षणीसहम् II
हे अश्विनी कुमारो! तुमने युद्ध में शत्रु पर विजय पाने वाले इंद्र के समान शत्रुओं पर विजय प्राप्त करने वाले, बलशाली श्वेत अश्व को पेदु के निमित्त प्रदान किया Ι
शर्यैरभिद्युं पृतनासु दुष्टरं चर्कृत्यमिन्द्रमिव चर्षणीसहम् II
हे अश्विनी कुमारो! तुमने युद्ध में शत्रु पर विजय पाने वाले इंद्र के समान शत्रुओं पर विजय प्राप्त करने वाले, बलशाली श्वेत अश्व को पेदु के निमित्त प्रदान किया Ι
अश्विनी = Bipolar Forces
श्वेत अश्व = White metal
The science of telegraphy is based on using a pure white metal(श्वेत अश्व) which are good conductor of electricity and possess the bipolar forces(अश्विनी). British fine art traders used to use the term "White Metal" for silver metal. White metal is also termed for the alloys which may include antimony, tin, lead, cadmium, bismuth and zinc. By the help of Bipolar forces(अश्विनी), you can make telegraphic apparatus. It is necessary for operations of military. But it should be used with precautions.