Fear seems so much the parent of superstition, that I attribute this saying to the women, who, as mothers, have usually a superstitious dread not only of evil spirits, but also of the evil eye of mortals towards their young ones. When, some twenty years ago, I was told by a Kentish countryman that the church bell was tolled to drive away evil spirits from a departing soul, I supposed the man to be profanely jocose; but since then I have travelled much in this country and on the Continent, and have seen enough to satisfy me that superstition prevails comparatively less in Asia than in Europe and the pages of "N. & Q." abundantly corroborate the opinion. H. N. * * * * * PHOTOGRAPHIC CORRESPONDENCE. _Stereoscopic Angles._--I am concerned that my definition and solution of stereoscopic angles (a misnomer, for it should be _space_) in "N. & Q.," with subsequent illustrations, have not satisfied MR. SHADBOLT, as I am thus obliged to once more request room in your pages, and this time for a rather long letter. When I asserted that my method is the only correct one, it behoved me to be prepared to prove it, which I am, and will now do. It seems that MR. SHADBOLT has not a knowledge of perspective, or, with a little reflection and trifling pains in linear demonstration on paper, he might have convinced himself of the accuracy of my method. It were well, then, to inform MR. SHADBOLT, that in perspective, planes parallel to the plane of delineation (in this case, the glass at back of camera) have no vanishing points; that planes at right angles to plane of delineation have but one; and that planes oblique have but one vanishing point, to the right or left, as it may be, of the observer's eye. This premised, let the subject be a wall 300 feet in length, with two abutments of one foot in front and five feet in projection, and each placed five feet from the central point of the wall, which is to have a plinth at its base, and a stone coping at top. On a pedestal four feet high, two feet wide, and six feet long, exactly midway betwixt the abutments, let an ass be placed, a boy astride him, a bag drawn before the boy, who holds up a long stick in line with the ass, &c., that is, facing the observer. The right distance for the observer's place is 450 feet. If the cameras be placed two inches and a half apart, on one line parallel to the wall, the stereographs will be in true perspective for the _two_ eyes, that is, all the planes at right angles to the plane of delineation will have _two_ vanishing points, which, being merely two inches and a half apart, will, in the stereoscope, flow easily into one opposite the eye; whilst the plinth, coping, and all lines parallel to them, will be perfectly horizontal; and the two pictures would create in the mind just such a conception as the same objects would if seen by the eyes naturally. This would be stereoscopic, true to nature, true to art, and, I affirm, correct.