166 ANNUAL, REPORT SMITHSONIAN INSTITUTION, 1908, 



Marconi, on June 2, 1896, filed a provisional specification " showing 

 two forms of apparatus, one similar to Lodge's 1894 apparatus using 

 ungrounded aerials for both sending and receiving and the other for 

 use " when transmitting through the earth or water " substantially 

 identical with Lodge's 1894 and PopofF's 1895 apparatus, with tapper 

 back, etc., and the receiving antenna only being grounded. 



Soon after, in July, 1896, Marconi arrived in England and made 

 a number of experiments for the English post-office at Salisbury 

 Plain and elsewhere, using ungrounded aerials and parabolic reflec- 

 tors and succeeded in reaching nearly 2 miles. 



On March 2, 1897, Marconi filed the complete specification in which 

 was included a statement that the transmitting antenna also could 

 be grounded. 



Lodge filed a jDrovisional specification '' showing radiating spheres, 

 but no antenna, on May 10, 1897. The complete specification filed on 

 February 5, 1898, shows as one form both antennae grounded and also 

 the use of an inductance wound in the form of a coil for the purpose 

 of diminishing the rate of damping of the waves. 



So far as is known little work was done in America during this 

 period. The writer made some experiments in 1896 and in conjunc- 

 tion with two of his students, Messrs. Bennett and Bradshaw, did 

 considerable work on receivers of various types in the fall of 1896 

 and spring of 1897, the results of which were incorporated in a 

 thesis.'' 



Return to First Principles and Foundation, on Lines Antithet- 

 ical TO Old, of New or Sustained Oscillation Non microphonic 

 Receiver Method (1898). 



Up to the year 1898, as may be seen from the above, the develop- 

 ment of wireless telegraphy had proceeded along a single line. In 

 that year, however, an entirely new method of wireless telegraphy 

 was developed, characterized by a return to first principles, the aban- 

 donment of the previously used methods and by the introduction of 

 methods in almost every respect their exact antitheses. 



While the coherer is of more or less interest theoretically it is not 

 adapted for use for telegraphic purposes. Responding as it does to 

 voltage rises above a certain limit, it does not discriminate between 

 impulses of different characters, and is therefore peculiarly suscep- 

 tible to interfering signals and atmospheric disturbances, and the 

 operation of coherer systems can not be guaranteed during the sum- 



« Marconi, Great Britain patent No. 120.39, 1896. 

 » Lodge, Great Britain patent No. 11575, 1897. 

 <' Western University of Pennsylvania, May, 1897. 



