"The shell is blown,
And the devil is flown."
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 promised, 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.
Now, let the same subject be treated by Professor Wheatstone's method, when the cameras would be eighteen feet apart. Situated thus, if placed on one line, and that parallel to the wall, the extreme end at the right could not be seen by the camera at the left, and vice versâ; so that they must radiate from the centre when the glass at back of camera would be oblique to the wall, and the plinth, coping, top and bottom of pedestal, would have two vanishing points, at opposite sides of the centre, or observer's eye; both sides of the ass, both the legs of boy, and two heads to the drum would be visible; whilst the two sides of pedestals would have each a vanishing point, serving for all lines parallel to them. But these vanishing points would be so far apart that they could not, in the stereoscope, flow into one: the result would be, that the buttresses would be wider at back than in front, as would also the pedestal, while the stick held by the boy would appear like two sticks united in front. This would be untrue to nature, false to art, preposterously absurd, and I pronounce it to be altogether erroneous.
This being the case with a long distance, so must it be with shorter distances, modified in exact proportion to the diminution of space between the cameras, &c. For, let the object be a piece of wood three feet long, four inches wide, and six inches deep, with a small square piece one inch and six inches high, placed upright exactly on a line from end to end of the three feet (that is, one at each end) and midway between the sides. Let this arrangement be placed across another piece of wood three or four feet long, which will thus be at right angles to the piece at top. By my method all will be correct—true to nature and to art, and perfectly stereoscopic: whilst by the radial method (recommended by Mr. Shadbolt), with two feet space for cameras, there would be the top piece divided at the farther end, where there would be two small upright pieces instead of one; and this because the two vanishing points could not, in stereoscope, flow into one: whilst the lower piece of wood would have two vanishing points at opposite sides. This, then, being untrue to nature, untrue in art, in short, a most absurd misrepresentation, I pronounce to be utterly wrong. I have made the space two feet between cameras in order to show how ridiculous those pictures might become where there is an absence of taste, as, by such a person, two or ten feet are as likely to be taken as any less offensively incorrect.