(iv) =Reasons for Estimates.=--Each observer should be asked by the instructor to give reasons for his estimate of distance to guard against the habit of rough guessing. To train observers in the habit of taking into account every factor which will help them to judge distance, the instructor should consider and explain the effects of local conditions and other factors which affect judging the distance of each object he indicates after the class have made their estimates. Ample time should at first be allowed for judging distance, but as progress is made the time should be limited. The above exercises must include instruction in estimating lateral distances. _Rough guessing is never to be allowed._ =5. Aids to Judging Distance by Eye.=--(i) The class should be trained in various methods of assisting the eye when the distance of objects is especially difficult to estimate approximately. For example, a maximum and minimum estimate of the distance may be made, and the mean taken as correct. Half the distance from the object may be estimated with the aid, if possible, of some feature of ground, and double may be taken as correct. When the object is partly hidden in a fold of ground, or when it is of unknown size, distance from it may be estimated with the help of some object of known size, such as a natural feature of the ground or a human figure which may be near it. (ii) Other rough methods which will assist them in judging distance approximately may be explained to the men. For instance, the foresight of the rifle _when correctly aligned_ will be approximately equal to the height of a standing figure at 400 yards. The width of an ordinary pencil held horizontally at arm’s length before the eye will cover an upright figure at 200 yards, and the lead at its thick part will cover a standing figure at 600 yards. =6. Tests in Judging Distance by Eye=--(i) =Directions regarding Tests.=--In every company, and at depôts, in addition to instructional exercises, at least one test in judging the distances of four objects will be held for all ranks in every three months, the distances of the objects being between 200 and 800 yards. All company officers, non-commissioned officers, and those men who are in possession of badges for judging distance, will also be tested once in every three months under regimental arrangements in judging the distances of four objects between 200 and 1,400 yards. Brigade commanders and officers commanding districts will issue such orders as may be necessary for exempting non-commissioned officers and men from these tests, but every officer and sergeant who would command a company or smaller unit on mobilization should attend four tests annually in judging distance up to 1,400 yards.