Being tolerably _au fait_ at these points of practice (for perfection can only result from long experience, whence come skill and judgment), it will be necessary that he bear in mind those rules for rightly effecting his purpose when his game is moving. He must shoot before an object that crosses his point of sight; high for a bird rising in its flight, or skimming the surface; between the ears of hares or rabbits running in a straight line from him,--being guided, of course, in every case, by the distance between him and the mark at which he aims. For example, if a bird range forty yards from him, calculating the ordinary velocity of its speed of wing, he may safely aim six inches before it. No fixed rules, however, can be laid down, where the casualties of powder, a dull or lively-shooting gun, high winds, and fifty other et ceteras, are opposed to a system. One principle he may always adopt with success, and that is, to fix his eyes on the mark he has selected, and fire _the instant_ the gun is brought to bear upon it. It is very difficult to say at what distance a bird may be which can be called a fair shot, because it rests with so many contingencies. Forty yards are generally considered as point-blank range, but it will often be found easier to bring down game at fifty than at thirty yards. The wind, as in cross shots, and various operating causes--all the result of temporary accident--must be taken into account. You will always have a better chance to kill long cross shots than those approaching or flying from you. It is very hard to do execution upon birds with a stern-chaser, and in coming towards you they present a surface off which shot is very apt to glance without penetrating. I have said nothing about the hold of his gun most convenient for the learner to accustom himself to, because, in whatever manner it may be put into his hands at first, he is sure, ultimately, to adopt a style of his own, arising from natural causes, or habits almost as forcible. The nearer it is placed to the guard, the less risk is run should a barrel burst. The grasp of the stock more forward affords the greatest facility in bringing the gun to bear upon its object, and more firmness of position.