3. The depth of the beaten zone of the machine gun is small as compared with that of collective rifle fire. This makes the effect of small errors in sighting for elevation proportionately greater. A section of machine guns cannot therefore be relied upon to make its fire effective when first opening fire, at distances beyond about 1,000 yards. If observation of fire is possible, elevation may be rapidly corrected, and the fire of the two guns may in that case be very effective up to 2,000 yards, or up to the limit of observation. If there is no observation it will be necessary to employ several guns and expend a large quantity of ammunition in order to obtain adequate assurance of effect beyond about 1,000 yards. 4. By massing the machine guns of a brigade the assurance of fire effect at ranges beyond 1,000 yards is increased, and it is easier to control and direct fire. At shorter ranges massed machine guns may form a conspicuous target, and the control of more than two guns then becomes difficult. Occasions will, however, often arise when the massed guns of a brigade can be brought into action in a well-concealed position within the limits of effective rifle range. Under such circumstances massed guns may produce great effect both in attack and defence. 5. The general considerations which govern the selection of a target for machine guns are--its tactical importance, its range, and its vulnerability. Machine guns should seldom engage artillery with direct fire beyond effective rifle range, for in such circumstances superiority of fire will always rest with the artillery if the machine guns are located. Within effective range machine guns, if concealed, should inflict considerable loss on artillery, while oblique fire may be usefully employed up to the limits of long rifle range. Engagements with thin lines of skirmishers should be avoided unless the range is accurately known, as the risk of disclosing the position of the gun and the expenditure of ammunition involved will rarely be justified by results. 6. It is very important that fire should not be opened until there is a reasonable probability of obtaining the desired result. A section commander must have a thorough knowledge of the capabilities of his guns to enable him to decide when he is justified in opening fire. 7. Machine guns should as a rule only open fire upon targets which are sufficiently large and dense to promise an adequate return for the ammunition expended. Special circumstances may, however, warrant the opening of fire upon less favourable targets. When a machine-gun commander has decided to open fire, the ammunition necessary to secure the results sought should be expended without hesitation. 8. If there is no satisfactory indication of effect, and no special justification for firing at long range exists, it will usually be better to withdraw from action and to await opportunities for effective intervention.