[1] It is here proper to observe that the term _wireless_ telegraphy, as applied to electrical systems, is misleading, since it implies the absence of wires; whereas in all systems wires are used. But since it is generally understood that by wireless telegraphy is meant telegraphy without _metal connections_, and because the more improved methods lessen more and more the amount of wire used, the phrase has been allowed to stand. About the same date a Scotchman, James Bowman Lindsay of Dundee, a man as rich in intellectual attainments as he was pecuniarily poor, sent signals in a similar manner across the River Tay. In September, 1859, Lindsay read a paper before the British Association at Dundee, in which he maintained that his experiments and calculations assured him that by running wires along the coasts of America and Great Britain, by using a battery having an acting surface of 130 square feet and immersed sheets of 3000 square feet, and a coil weighing 300 lbs., he could send messages from Britain to America. Want of money prevented the poor scholar of Dundee from carrying out his experiments on a large enough scale to obtain public support. He died in 1862, leaving behind him the reputation of a man who in the face of the greatest difficulties made extraordinary electrical discoveries at the cost of unceasing labour; and this in spite of the fact that he had undertaken and partly executed a gigantic dictionary in fifty different languages! [Illustration: _M. Marconi’s Travelling Station for Wireless Telegraphy._] The transmission of electrical signals through matter, metal, earth, or water, is effected by _conduction_, or the _leading_ of the currents in a circuit. When we come to deal with aërial transmission, _i.e._ where one or both wires are replaced by the ether, then two methods are possible, those of _induction_ and Hertzian waves. To take the induction method first. Whenever a current is sent through a wire magnetism is set up in the ether surrounding the wire, which becomes the core of a “magnetic field.” The magnetic waves extend for an indefinite distance on all sides, and on meeting a wire _parallel_ to the electrified wire _induce_ in it a _dynamical_ current similar to that which caused them. Wherever electricity is present there is magnetism also, and _vice versâ_. Electricity--produces magnetism--produces electricity. The invention of the Bell telephone enabled telegraphers to take advantage of this law.