The effect of _distance_:--When the bullet is fired from a distance, but with full effect, the hole is clean cut and presents the characteristics enumerated above. When the bullet is ‘spent’, the osseous injury at the point of impact is usually of a more extensive character than when the bullet possesses a higher degree of velocity. When fired at close quarters the damage incurred from the impact of the bullet is increased by the force of the forwardly driven air and gas. The skull suffers proportionately, the scalp being severely lacerated, burnt, and circumferentially ingrained with powder, the bone extensively comminuted, and the brain severely lacerated. The effect of _size and shape_ of the bullet:--The effects produced on the skull in relation to the size and shapes of the bullet are so obvious as to require no description. The nature of the bullet must also be taken into consideration, whether of the soft-nosed variety, expansile, &c. The effect of the _angle of impact_:--The lesion produced by the bullet varies according as to whether the bullet glances across the vault or strikes the bone at right angles. In the former case a ‘gutter’ fracture may result, varying in degree and associated brain complication according to the angle of impact. In the latter case the skull is penetrated or perforated. The effect of the _position of the bullet_ at the moment of impact:--The bullet, at the moment of impact, may be so changed in position--head-over-heels, ricochet, &c.--that the skull may be struck by its long axis instead of by its nose. In such cases, the wound of entry will be more extensive than under ordinary circumstances. It is obvious, therefore, that many factors require consideration in estimating the extent of the osseous lesion and the nature of the complications existent in any given case. Due allowance must also be paid to other factors entering into the case, more especially in relation to the weapon used--pistol, revolver, gun, &c. =Injury to the bone.= The various injuries to bone may be classified as follows:-- Fractures limited to the external table. Fractures limited to the internal table. Gutter fractures. The complete fractures produced by a penetrating wound. The complete fractures produced by a perforating wound. =Fractures limited to the external table.= Fractures of this nature are of exceedingly rare occurrence. They are produced by a bullet which strikes the skull in such an oblique direction that the scalp and external table are torn away (‘gutter’ fractures), or by a bullet which, directed against the outer wall of the frontal sinus, possesses sufficient force to comminute the outer wall of that sinus, but, from loss of momentum, is incapable of penetrating further.