TELEGRAPHY ACROSS SPACE. 245 



impedance coil. By this means the oscillations can be accurately 

 tuned. The receiving apparatus is also tuned ; in fact, each apparatus 

 is made to operate both as emitter and as receiver in turn, as required. 

 Lodge has also modified the arrangements of the coherer circuits, to 

 render them more certain of operation, no local current being allowed 

 to pass through the coherer until after it had been affected by the 

 waves. He has, in fact, thoroughly redesigned the sending and 

 receiving instruments upon a rational basis, so that they shall be both 

 less sensitive to stray impulses and more sensitive to properly attuned 

 waves. The results obtained with these have not yet been made public ; 

 but employing a siphon recorder as the receiving instrument,remarkable 

 precision of signaling has been attained. Further developments in this 

 direction will doubtless be awaited with much interest. Meantime, in 

 other countries, the United States, Russia, and France, other experi- 

 menters are at work. Any account given at the present time will 

 therefore be necessarily incomplete. 



In passing finally from a review of that which has already been 

 attained to that which may reasonably be contemplated as within 

 reach of attainment in the near future, I have no wish to assume the 

 role of the prophet. Still less would I desire to emulate the example 

 of the imaginative litterateur who, whether his name be Jules Verne 

 or H. Gr. Wells, stimulates the public curiosity by amazing speculations, 

 and in doing so renders the disservice that the public so stimulated is 

 made less capable than before of distinguishing between that which is 

 and that which is not within the bounds of reasonable possibility. 



It has been shown that there are three general methods of trans- 

 mitting electric siguals across space. All of them require base lines 

 or base areas. The first, conduction, requires moist earth or water as 

 a medium, and is for distances of less than 3 miles the most effective 

 of the three. The second, induction, is not dependent upon earth or 

 water, but will equally well cross air or dry rock. The third, electric- 

 wave propagation, requires no medium beyond that of the ether of 

 space, and is, indeed, interfered with by interposing things, such as 

 masts and trees. Given proper base lines or base areas, given adequate 

 methods of throwing electric energy into the transmitting system and 

 sufficiently sensitive instruments to pick up and translate the signals, 

 it is possible, in my opinion, to so develop each of the three methods 

 that by any one of them it will be possible to establish electric 

 communication between England and America across the intervening 

 space. It is certainly possible either by conduction or by induction ; 

 whether by waves I am somewhat less certain. Conduction might 

 very seriously interfere with other electric agencies, since the waste 

 currents in the neighborhood of the primary base line would be very 

 great. It is certainly possible either by conduction or induction to 

 establish direct communication across space with either the Cape or 

 India or Australia (under the same assumptions as before) and at a far 



