DECEMBER 17, 1897. ] 
It is curious that hills and apparent ob- 
structions fail to obstruct. The reason is 
probably the fact that the lines of force 
escape these hills. When the ether is en- 
tangled in matter of different degrees of in- 
ductivity the lines are curved, as in fact they 
are in light. Fig 4 shows how a hill is vir- 
Fie. 4. Diagram illustrating the way in which hills 
are bridged by the electric waves. 
tually bridged over by these lines, and con- 
sequently some electric waves fall on the 
relay. Weather seems to have no influence 
—rain, fogs, snow and wind avail nothing. 
The wings in Fig. 2 may be removed. 
One pole can be connected with earth, and 
the other extended up to the top of the 
mast, or fastened to a balloon by means of 
a wire. The wire and balloon or kite cov- 
ered with tin foil becomes the wing. In 
Aluminium Wire 
SPRL CO 
vs 
Fie. 5. Diagram of Marconi connections when 
using pole or kite. 
SCIENCE. 
895 
this case one pole of the transmitter must 
also be connected with the earth. This is 
shown by Fig. 5. 
There are some apparent anomalies that 
have developed themselves during the ex- 
periments. Mr. Marconi finds that his re- 
lay acts even when it is placed in a perfectly 
closed metallic box. This is the fact that 
has given rise to the rumor that he can 
blow up aniron-clad ship. This might be 
true if he could plant his properly tuned 
+ receiver in the magazine of an enemy’s ship. 
Many other funny things could be done if 
this were possible. I remember in my 
childhood that Captain Warner blew up a 
ship at a great distance off Brighton. How 
this was done was never known, for his 
secret died shortly afterwards with him. 
It certainly was not by means of Marconi’s 
relay. 
The distance to which signals have becn 
sent is remarkable. On Salisbury Plain 
Mr. Marconi covered a distance of four 
miles. Inthe Bristol Channel this has been 
extended to over eight miles, and we have 
by no means reached the limit. It is inter- 
esting to read thesurmises of others. Half 
a mile was the wildest dream.* 
It is easy to transmit many messages in 
any direction at the same time. It is only 
necessary to tune the transmitters and re- 
ceivers to the same frequency or ‘note.’ I 
could show this here, but we are bothered 
by reflection from the walls. This does not 
happenin openspace. Tuning is very easy. 
It is simply necessary to vary the capacity 
of the receiver, and this is done by increas- 
* “Unfortunately at present we cannot detect the 
electro-magnetic waves more than 100 feet from their 
source.’? Trowbridge, 1897, What is Electricity, p. 
256. 
“‘T mention 40 yards because that was one of the . 
first out-of-door experiments, but I should think that 
something more like half a mile was nearer the limit 
ofsensibility. However, this isa rash statement not 
at present verified.’’? Oliver Lodge, 1894, The Work 
of Hertz, p. 18. 
