Communication with the reconnoitring squadrons can practically never be carried out by wireless telegraphy. Here efforts must be made to work with the light-signal apparatus,[7] or to employ cyclists or relay lines to facilitate and accelerate the service of transmission. A combination of all these means, and the use of the cavalry telegraph, if need be, will be found advisable. In friendly country the population can often be used to keep up communication or to send messages. The employment of single cyclists or motor-cars is, on the other hand, not advisable. Without taking into account the fact that they are tied to the roads, and, having no fighting value, will often fall an easy prey to the enemy, technical defects occur so often in the machines that they cannot be classed as a reliable means of communication, particularly in hostile country. Should the distance between the reconnoitring squadrons and the main body become very great, or if circumstances arise which render direct communication between them too long a matter, or if it is desired to provide several avenues of communication, a collecting station can be formed for reports: this will keep up connection, and must be secured by a detachment of sufficient strength. It is erroneous to assume that such collecting stations must always be used. They often operate very unfavourably, especially when armies are on the move, as they are for the most part very local, and then do more harm than good. If there is a sufficient number of apparatus at disposal, and if the collecting stations are sufficiently secured, an effort should be made to establish wireless communication from them to the rear--a cipher being of course used to prevent the enemy learning the contents of messages. Otherwise the various means available must be suited to the particular case, and used in combination. The system of communications thus forms a complicated machine, formed of technical and natural methods of transmission of great variety, that will be difficult to maintain in an efficient state, especially when an army is on the move. It is obvious that these difficulties must be augmented during the change of reconnoitring zones or the relief of reconnoitring squadrons. It will often be worth while to establish the system of intelligence in a new direction, while the available apparatus and telegraphs are still in part maintained on the old lines. Only some "system of auxiliaries" will meet these difficulties; only troops to whom this service has been entrusted down to the smallest detail will be able to discover these auxiliaries and properly employ them. Otherwise the service of information must miscarry. 2. _Reconnoitring Squadrons_