LAND RADIO EQUIPMENT.
- Spark sets, sending and receiving (three types).
- Continuous-wave Army radio telegraph sets (three types).
- Radio telephone set (one type).
- Tank radio telegraph set (one type).
- T. P. S. (earth telegraphy) (four types).
- Wavemeters.
- Battery-charging sets.
- Radio operating and repair trucks.
- Miscellaneous special equipment.
AIRPLANE RADIO EQUIPMENT.
- Interphone sets (for use of two to five persons).
- Radio telephone sets (three types).
- Radio telegraph sets (three types).
- Direction-finding radio-receiving set (one type).
The magnitude of the production of special items involved may be gathered from such figures of expenditures as the following:
| For vacuum tubes | $1,650,600 |
| For storage batteries | 5,315,350 |
| For dry batteries | 602,470 |
| For battery charging sets | 1,524,400 |
These are, of course, only some of the items. The total production authorized was valued at approximately $45,000,000.
The remarkable development and improvement of military radio equipment which has taken place under the direction of the Signal Corps during the last 18 months will undoubtedly materially change the system of Army communications and even the tactical use of military equipment and personnel. A typical example of this development is the airplane radio telephone, described elsewhere, the use of which has made possible the "voice-commanded air squadron." The military value of an air squadron has been enormously increased by virtue of this device, which enables the squadron commander to direct the movements of the individual airplanes in any manner which circumstances may require.
Certain other radio devices recently perfected, the nature of which can not be revealed, will undoubtedly affect the tactical use of troops to such an extent as to make certain kinds of radio equipment as indispensable to the operations of military units as the rifle or the machine gun.