THE IMPRESSIONS RESULT FROM SOME ACTION WITHOUT CONTACT
It remains for us to discover the natural law which has produced these impressions, which are something more than stains.
We have pointed out the grave defects which there must be in all impressions made by contact which attempt to reproduce the natural image of a delicately moulded subject. We shall try to learn what sort of action other than direct contact has influenced the production of the impressions on the Shroud of Turin.
Every painting represents things not as they are in reality, but as they appear when projected on a flat surface. Impressions by simple contact cannot produce this effect. Yet this is what we find on the Shroud of Turin.
Take any solid object—a sphere, a cube—no matter what. Suspend it in the air and look at it from underneath. Draw it in this position ; the drawing has the same form as the projection of the object on a horizontal plane. In other words, if from a number of points on our object we let fall the same number of weighted threads, these threads will mark out in plan a figure which is the projection of the suspended object. The drawing will be identical with this projection if it is the same size as the object produced.
If we make the drawing smaller, it will not be the same size, but will be in strict proportion to it.
It is not easy to draw from below an object suspended overhead, but our argument holds good from whatever position we look at an object.
We will only deal as yet with objects of little depth. If our drawing has to represent numerous concave objects on different planes we shall have to consider not only the laws of projection, but also those of perspective. It is enough that every picture represents a fragment of nature reproduced upon a flat surface.
So much for the outline ; but we have yet to consider the shading by which this outline, though flat, shall be made to resemble rounded or hollowed forms.
Here we have no fixed rules. All depends on the way the light falls on the object. We must endeavour to give faithfully the relative shadows as our eyes see them. The portions which receive the rays of light directly will be more highly illumined than the parts which fall away from the light. In like manner the concave surfaces will be darker than the convex.
Let us examine the back of a hand held quite straight with the fingers close together, so that the light falls full upon it. The moulding of the fingers will be as we have described, and the hollows between the fingers will be in dark shadow, deepening where the fingers come in contact.
These facts are familiar to every one, and there is no need to enter into longer explanations of what is lacking in the case of contact-prints. The representation of the head on the Holy Shroud cannot be a print made in this way.
In Plate in. the head looks as if the concave and convex surfaces had been projected on a plane, that is to say drawn or photographed. The modelling is almost as if the light had been from the front. I say almost because some parts seem shaded as if the light came from above, but I shall allude to these further on. This head, then, may be said to be almost the equivalent of a drawing, or even of an ordinary photograph taken through a lens. Yet we know that it is not a drawing, and if it is something of the nature of a photograph it is certainly not an ordinary one. We are speaking now of the head converted to the positive. Let us look at it as it is actually seen on the cloth (Plates n. and iv.). Here we see it projected on a plane, but with all the modelling reversed. The convex portions are the darkest, the hollows are the lightest, just as if it were printed by contact.
But note this difference, a most important one. There is no distortion in the features, and the modelling, though it seems elementary, is yet so correct that the head, in its positive aspect, looks like a drawing by a good artist.
We are nearing the solution of our problem, or at least the partial solution, and shall shortly understand the physical characteristics of the impression on the Holy Shroud.
In the first place it really is a sort of imprint or impression, and it conforms to the general rules of impressions. On the one hand, if the cloth is stretched flat, it will rest only on prominent parts of the body ; on the other hand, if the cloth is not flat, if it is wrapped round the body, it will come in contact with the different planes of the body successively, and the impression will be thus greatly distorted.
In the case in point, if we look for the sides of the face, the shoulders, the ears, the neck, we shall not find them— we must conclude that the linen has not touched those parts. On the other hand, in the front view of the figure, the calves, and also the ankles, which coincide approximately with the lower edge of the photograph, bear evident traces of wrapping. Thus the impression is distorted in the one instance by too much contact, and in the other by too little.
But the figures are produced by some more delicate process than simple contact, since in many parts of the body, and notably on the face, the modelling is excellent.
In the front view of the figure there is no deformation of the parts where the linen lay in approximately one plane.
But if nevertheless in these very places there is also shaded modelling, as in a drawing, it must indicate that on this stretched linen a projection has taken place. Some emanation from the body has acted on the linen, and since the hollows on the Shroud are less vigorously reproduced than the raised portions it must be admitted that this something worked with less intensity in proportion as the distance from the body increased.
Is not the law which this something followed simply the law of distance which governs all natural phenomena ? Under this law effect increases or decreases as the square of the distance, in more or less degree, dependent upon attendant conditions.
In the present case it is indeed hard to determine with what rapidity the unknown action took place between the body and the Shroud; the main point is that we can assert that the action diminished in proportion as the distance of the body from the Shroud increased. We may almost affirm that the decrease was rapid, as the cloth has evidently not received any impression from certain portions of the face and body, no doubt those from which it was too far distant. Thus it is that before making any detailed examination we are able to assert that the impressions are negatives, because the raised parts of the body are reproduced strongly while the hollows have given fainter impressions in proportion to their distance from the cloth.
A print by simple contact, we have seen, produces a negative impression, but a very rough and coarse negative.
In order that the body should act on the cloth, actual contact—no matter how slight—is required. The print on the Holy Shroud is a still more perfect negative, because the image has been also in part produced without contact. Nevertheless we do not pretend that this negative is as true a one as if it had been taken by means of a lens.
To sum up : an impression has been formed on the Shroud. The figure produced is not to be called a photograph, because light has had no part in forming it. In the language of science it is the result of action at a distance (that is to say without contact); geometrically speaking it is a projection. In short, we have before us the equivalent of a rough sketch which has been shaded negatively.
Later on we will argue what name chemical science may give to this impression.