(ii) Unless service targets are closely watched while aiming, the firer will be apt to lose them altogether, or see them as a blurred image at the moment of firing, with consequent loss of fire effect. For this reason it is of great importance that recruits should, from the earliest stage of their training, be taught to aim at service targets _with the eye focussed on the target_, and not on the foresight. If early stages of instruction were confined to the aiming at the bull’s-eye target, the fault of focussing the eye on the foresight in aiming might be contracted owing to the distinct nature of this mark, which makes it possible to aim at it with the eye fixed on the foresight. (See Appendix, VII., para. 2.) Section =18=.--Triangle of Error. =1.= The following method of recording a triangle of error will be employed to test proficiency in aiming, and to demonstrate the errors which will arise from inaccuracies. =2.= The rifle will be placed on an aiming-rest, and pointed at a sheet of blank white paper, fixed to any convenient object at a distance of about 10 yards from the muzzle. A second aiming-rest should be used to steady the head in aiming. =3.= A marker will hold an aiming-disc flat on the paper, the front facing the instructor. The instructor will align the sights on it correctly, and its position on the paper will then be marked by a dot made with a pencil passed through the hole in its centre. =4.= Each man in succession will then be called up and ordered to look along the sights, but without touching the rifle, and when he has satisfied himself as to the correctness of the aim, the disc will be removed. It will then be replaced on the paper as before, and moved at his direction until the lower edge of the bull’s-eye is brought into the line of sight, when its position will be marked as before. This operation will be repeated three times in the case of each man, and the points thus fixed will be joined in such a way as to form a triangle. [Illustration: B. _Horizontal_ A. _Vertical_ =Fig. 14.=--TRIANGLE OF ERROR] =5.= The position of these points in relation to the _instructor’s aim_ will expose any constant error in aiming. If the recruit’s aim is below that of the instructor, it shows that he has taken too full a sight; if above, that his sighting has been too fine; if to the right, that the foresight was on the left of a perpendicular drawn through the centre of the notch; if to the left, _vice versa_. =6.= The position of the points in regard _to one another_ will show _inconsistency_. If the triangle is formed so that its greatest side lies vertically on the paper, it proves that the soldier’s principal fault is inconsistency in respect of _the amount of foresight taken up into the line of sight_ (Fig. 14, A); if the greatest side of the triangle lies horizontally it shows that his principal error is _inaccurate centring of the foresight_ (Fig. 14, B).