_Brewster on the Use of Two Eyes._—As the novice who has not devoted much thought to the subject of shooting, will be apt to feel some surprise at the idea of the use of both eyes being recommended in taking aim, the liberty will be assumed of quoting a paragraph from the writings of Sir David Brewster, offering it as evidence in substantiation of the foregoing position. In his able work on the Stereoscope he says: “When we look with both eyes open at a sphere, or any other solid object, we see it by uniting into one two pictures—one as seen by the right, and the other as seen by the left eye. If we hold up a thin book perpendicularly, and midway between both eyes, we see distinctly the back of it and both sides with the eyes open. When we shut the right eye, we see with the left eye the back of the book and the left side of it; and when we shut the left eye, we see with the right eye the back of it and the right side. The picture of the book, therefore, which we see with both eyes, consists of two dissimilar pictures united, namely, a picture of the back and left side of the book as seen by the left eye, and a picture of the back and right side of the book as seen by the right eye.” This argues that the sportsman who closes one eye at the time of taking aim at an away-going bird, really has a very imperfect view of it—but half a picture, as it were—hence the aim could not possibly be so perfect as in case where the picture was rendered more distinct by the use of both eyes, in accordance with the clear explanation of Sir David, who goes on to state: “But though we see with one eye the direction in which any object or point of an object is situated, we do not see its position or the distance from the eye at which it is placed. In monocular vision we learn from experience to estimate all distances, but particularly great ones, by various tests, which are called the _criteria_ of distance, but it is only with both eyes that we can estimate with anything like accuracy the distance of objects not far from us. “The most important advantage which we derive from the use of two eyes is to enable us to see distance, or a third dimension in space. That this vision is not the result of experience as monocular vision is, is obvious from the fact that distance is seen as perfectly by children as by adults; and it has been proved by naturalists that animals newly-born appreciate distance with the greatest correctness.” _Dougall’s Reasoning._—Mr. Dougall says, in his “Shooting Simplified,” that “A thorough good gun will knock over a hare running broadside, with four or five shots at seventy yards distance, but full elevation must be taken, and the gun fired with the head well raised and the eyes kept steady on the aim, _not_ taking sight along the rib, with the eye well down behind the breech, as has been erroneously recommended.