190 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1919. 
NEW TYPE OF APPARATUS. 
Experience in the operation of the above type of wireless telephone 
apparatus indicated the desirability of certain improvements, par- 
ticularly along the following lines: 
Reduction in the size of the apparatus units to better 
adapt them to installation in the restricted space available 
on certain types of airplanes. 
Use of very much shorter wave lengths to make possible 
the substitution of antenne which would not interfere with 
the use of the airplane and which would likewise reduce the 
amount of radio interference which would be experienced on 
the western front. 
Accordingly, a new type of set was developed during the summer 
of 1918, the essential elements of which are illustrated in plates 5 
and 6. Practical trials of this equipment have not proceeded suffi- 
ciently to indicate the superiority of this set from the standpoint of 
its use by the aviator. Its superiority, however, from the standpoint 
of installation is self-evident. 
WIRELESS VERSUS WIRE TELEPHONY. 
Any prophecy as to the future of the wireless telephone art should 
take due account of fundamental differences between wire and wire- 
less telephony. While it is conceivable, though not probable, that 
improvements in directive radiation may be evolved which will cause 
the greater part of the waves radiated from a wireless station to 
choose a particular path, rather than to be spread broadcast, as at 
present, there will always be a far more definite and restricted path 
for wire telephone signals than for wireless signals. As a result, it 
may be safely predicted that wireless telephony is not apt to supersede 
wire telephony in any of the fields now occupied by the latter. The 
application of wireless telephony to new fields, where wire telephony 
is either impossible or impractical from economic considerations, will 
furnish abundant opportunity for service of the greatest value. A 
combination of wire and wireless telephony, each in its own field, 
may result ultimately in a telephone system covering the civilized 
world. 
COMMERCIAL FIELD. 
To the average person the most interesting commercial application 
of wireless telephony is transoceanic, such as is suggested by the long- 
distance experiments mentioned above. While the scientific aspects 
of the question are such that the development of suitable apparatus 
for effecting reliable commercial service between such points as New 
