348 



Canadian Forestry Journal, September, 1919 



TREE WIRELESS" — A NEW APPLICATION 



Bp Douglas R. p. Coats, Montreal. 



No More Elaborate Towers and Expensive Aerials Liable to 

 Breakdown — Just Trees Themselves. 



An article of great interest to me as a 

 wireless man, but particularly so on account 

 of my experiences as demonstrator of radio- 

 lelegrapli equipment on the Canadian Forestry 

 Association's exhibition car last year, appears 

 in the "Electrical Experimenter" for July. 



In this article, Major-General Squier, Chief 

 Signal Officer, United States Army, describes 

 some experiments in which he has used growing 

 trees as radio "antennae" with remarkable suc- 

 cess. The layman who has seen wireless sta- 

 tions or pictures of them will have noticed the 

 high masts or towers and the elevated arrange- 

 ment of wires which have become so associated 

 in' our minds with wireless stations as to make 

 us think of their threatened existence — for sci- 

 ence is declaring them unnecessary -with the 

 same feelings of regret with which we note the 

 disappearance of revered landmarks. Radio 

 engineers, however, have been eyemg these pic- 

 turesque structures with entirely different sen- 

 sations, begrudging the cost of materials re- 

 quired in their construction and maintenance, 

 but objecting particularly to their prominence 

 where secrecy of location would be most desir- 

 able, for the average wireless mast simply will 

 not be "camouflaged!" 



In non-technical language, the prime func- 

 tion of the aerial is that of radiating energy 

 from the transmitter into space in the form of 

 aether waves, which, meeting aerial systems 

 at receiving stations elsewhere, can be ab- 

 sorbed and converted into audible signals. Gen- 

 erally speaking, the waves emitted from a sta- 

 tion are radiated fairly equally in all directions, 

 though m many cases aerials are constructed 

 with distinctly directional properties, that is to 

 say, the bulk of their energy may be propa- 

 gated so as to produce a much greater effect 

 on a receiver situated at the point. It is ob- 

 vious that if energy is radiated in all directions, 

 the amount absorbed by any one receiver must 

 be extremely small, and even where both trans- 

 mitting and receiving aerials are designed to 

 have strong directive properties one to the 

 other, the waste of energy is still so enormous 



as to necessitate elaborate aerial systems at each 

 station and the use of very delicate receivers 

 responsive to the feeblest currents. 



Amplifying Sound. 



Recent advances in receiving apparatus have 

 now revolutionized radio communication to 

 such an extent that we hear of signals quite 

 inaudible with types of receiver used only a 

 few years back being amplified several million 

 times so as to produce sounds of such intensity 

 as to permit the operator to place his head tele- 

 phones on the table, walk a hundred feet or 

 more away and still hear them! As a result of 

 these improvements the transmission range of 

 any given powered apparatus may be said to 

 have been increased, though not in the strictest 

 sense, for it is not so much that signals can be 

 made to go farther today with a given input 

 of power than hitherto, though this is also true, 

 but rather that the sensitiveness of receiving 

 instruments has been so increased as to permit 

 of their being detected at greater distance. 



With signals amplified as we are able to do 

 today, we can get along minus any receiving 

 aerial at all in many cases — unless a simple 

 loop of wire suspended in the operating room 

 may be called an aerial — with an arrangement 

 of buried wires such as was invented by a Mr. 

 Hughes in the States and used for communi- 

 cation with submarines, or with what may be 

 found most suitable for wireless in Canada's 

 forests -a "tree aerial" system as worked out 

 by Major-General Squier. 



How a Tree is Used. 



In his article he says that radio messages 

 have been received in America from England, 

 France, Germany and Italy by connecting a 

 wire attached to a nail driven into a tree! The 

 nail is driven near the top of the tree, and 

 the insulated wire is joined to a small piece of 

 wire netting laid on the ground beneath the 

 tree. "One of the best arrangements is found 

 to be an elevated tree terminal in the upper 

 part of the tree-top and an earth consisting 



