=2. Methods of Ranging.=--(i) The principal means of ranging are--(_a_) Judging distance by eye; (_b_) observation of fire; (_c_) use of instruments such as the mekometer and the one-man range-finder. There are several auxiliary methods of ranging such as back-reckoning, use of maps, information obtained from aircraft, artillery or machine-guns, sound and flash, cross-bearings, etc., which may be used occasionally or in exceptional cases. (ii) Observation of fire, when possible, is an effective means of ranging. If uncertainty exists as to elevation, it is better to underestimate than to overestimate the range. If it is necessary to fire at ranges beyond 1,000 yards, and observation is not possible, or the situation demands that some effect should be produced, quickly combined sights may be employed. In all cases every available means should be employed to find correct ranges. _No available means of ascertaining ranges should ever be neglected, if time and opportunity allow them to be used._ =3. Reconnaissance as an Aid to Ranging.=--As already stated, range-finding will as a rule be in progress before fire is opened, and the rapid reconnaissance of any ground on which a fire-fight is likely to take place should provide information of the greatest value to company officers responsible for the direction of fire. In preparing a defensive position, there is usually ample time for ascertaining ranges, and for using range-marks (Sec. 40, para. 5) and preparing range-cards (Sec. 40, para. 1). =4. Training of Officers and N.C.O.’s.=--As fire is controlled at longer ranges, practice in judging distance is more necessary for officers and non-commissioned officers than for the private soldier. Soldiers who show aptitude in judging short distances by eye should, however, be given training with their leaders at judging longer distances. These men may also be selected for training in the use of range-finding instruments and in the duties of observers (Sec. 42, para. 9). =5. Reduction of Errors by Training.=--Officers and non-commissioned officers, by constant practice, will reduce their mean error in judging distance from about 20 per cent. of the correct distance to about 10 per cent., but much depends on the local conditions to which the observer is accustomed. With thorough training the mean error of private soldiers in judging distances within 800 yards should not exceed 100 yards. Special attention should be paid to men whose mean errors exceed this distance, with a view to discovering the cause and reducing the error. =6. Effect of Strange Conditions.=--Serious errors must be expected in judging under strange conditions of ground and atmosphere. Exercises in judging distance must therefore be carried out before, as well as during, military operations in unfamiliar country. Section =37=.--Judging Distances by Eye.