Read Ebook: Scientific American Supplement No. 460 October 25 1884 by Various

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I venture to claim for this method of detecting fire-damp among other advantages: 1. The detecter, on account of its size, can be placed in a break in the roof where an ordinary lamp--even a small Davy--could not be put, and a purer sample of the suspected atmosphere is obtained than would be the case even a few inches below the level of the roof, 2. The obtaining and testing of a sample in the manner above described takes away the possibility of an explosion, which might be the result if a lamp with a defective gauze were placed in an explosive atmosphere. No one knows how many explosions have not been caused by the fire-trier himself. This will now be avoided. 3. The lamp can be kept in a pure atmosphere while the sample is obtained by the detecter, and at a greater height than the flame in a safety-lamp could be properly distinguished. The test can afterward be made in a safe place, at some distance from the explosive atmosphere; and, owing to the vacuum formed, the ball has been carried a mile or more without the gas escaping. 4. The detecter supplies a better knowledge of the condition of the working places, especially in breaks and cavities in the roof; which latter, with the help of a nozzle and staff, may be reached to a height of ten feet or more, by the detecter being pressed against the roof and sides, or by the use of a special form of detecter. 5. Being able at will to force the contents of the detecter on to the flame, the effects of an explosion inside the lamp need not be feared. 6. The use of the detecter will permit the further protection of the present tin shield lamp, by an extra thickness of gauze, if such addition is found advantageous in resisting an increased velocity. 7. In the Mueseler, Stephenson, and other lamps, where the flame is surrounded by glass, there is no means of using the wire for shot firing. The detecter tube, although protected by two thicknesses of gauze, admits of this being done by the use of a special form of valve turned by the mouthpiece of the detecter. The system of firing shots or using open lamps in the same pit where safety lamps are used is exceedingly objectionable; still, under certain conditions shots may be fired without danger. Whether safety lamps or candles are used, it is thought the use of the detecter will afford such a ready means of testing that more examinations will be made before firing a shot, thereby insuring greater safety. 8. In testing for gas with a safety lamp there is a fear of the light being extinguished, when the lamp is suddenly placed in a quantity of gas, or in endeavoring to get a very small light; this is especially the case with some kinds of lamps. With the detecter this is avoided, as a large flame can be used, which is considered by some a preferable means of testing for small quantities; and the test can be made without risk. Where gas is present in large quantities, the blue flame at the end of the test tube will be found a further proof. This latter result is produced by the slightest compression of the ball. As regards the use of the detecter with open lights, several of the foregoing advantages or modifications of them will apply. Instead of having to use the safety lamp as at present, it is thought that the working place will be more frequently examined, for a sample of the suspected atmosphere can be carried to a safe place and forced on to the naked light, when, if gas be present, it simply burns at the end of the mouthpiece like an ordinary gas jet. There are other advantages, such as examining the return airways without exposing the lamp, etc., which will be apparent, and become of more or less importance according to the conditions under which the tests are made.

In conclusion, I wish to paint out that the practice adopted at some collieries, of having all the men supplied with the most approved lamp is not a safe one. If the strength of a chain is only equal to the weakest link, it may be argued that the safety of a mine is only equal to that of the most careless man or most unsafe lamp in it. If, therefore, the deputies, whose duty it is to look for gas and travel the most dangerous parts of the mine, are obliged to use the Davy on account of its sensitiveness, may it not be said that, as their lamps are exposed equally with the workmen's to the high velocities of air, they are the weak links in the safety of the mine? For the reasons given, I venture to submit that the difficulties and dangers I have mentioned will be largely reduced, if not wholly overcome, by the use of the fire-damp detecter.

CAMERA ATTACHMENT FOR PAPER PHOTO NEGATIVES.

In computing the weight of the various items for a photographic tour, the glass almost invariably comes out at the head of the list, and the farther or longer the journey, so much more does the weight of the plates stand out pre-eminent; indeed, if one goes out on a trip with only three dozen half-plates, the glass will probably weigh nearly as much as camera, backs, and tripod, in spite of the stipulation with the maker to supply plates on "thin glass."

Next in importance to glass as a support comes paper, and it is quite easy to understand that the tourist in out of the way parts might be able to take an apparatus containing a roll of sensitive paper, when it would be altogether impracticable for him to take an equivalent surface of coated glass, and in such a case the roller slide becomes of especial value.

The remarkable similarity of such a slide to the automatic printing-frame described last week will strike the reader; and, like the printing-frame, it possesses the advantage of speed in working--no small consideration to the photographer in a distant, and possibly hostile, country.

Fine paper well sized with an insoluble size and coated with a sensitive emulsion is, we believe, the very best material to use in the roller slide; and such a paper might be made in long lengths at a very low price, a coating machine similar to that constructed for use in making carbon tissue being employed. We have used such paper with success, and hope that some manufacturer will introduce it into commerce before long. But the question suggests itself, how are the paper negatives to be rendered transparent, and how is the grain of the paper to be obliterated? Simply by pressure, as extremely heavy rolling will render such paper almost as transparent as glass, a fact abundantly demonstrated by Mr. Woodbury in his experiments on the Photo-Filigrane process, and confirmed by some trials which we have made.

INSTANTANEOUS PHOTO SHUTTER.

SULPHUROUS ACID.--EASY METHOD OF PREPARATION FOR PHOTOGRAPHIC PURPOSES.

In the illustration given above, A and B are two bottles, both of which can be closed tightly with corks. A hole is made in the cork in the bottle, A, a little smaller than the glass tube which connects A and B. It is filed out with a rat-tail file until it is large enough to admit the tube very tightly. The tube may be bent easily, by being heated over a common fish-tail gas burner or over the top of the chimney of a kerosene lamp, so as to form two right angles, one end extending close to the bottom of the bottle B as shown.

Having fitted up the apparatus, about two ounces of hyposulphite of soda are placed in the bottle A, while the bottle B is about three-fourths filled with water--distilled or melted ice water is to be preferred; some sulphuric acid--about two ounces--is now diluted with about twice its bulk of water, by first putting the water into a dish and pouring in the acid in a steady stream, stirring meanwhile. It is well to set the dish in a sink, to avoid any damage which might occur through the breaking of the dish by the heat produced; when cool, the solution is ready for use and may be kept in a bottle.

The cork which serves to adapt the bent tube to the bottle A is now just removed for an instant, the other end remaining in the water in bottle B, and about two or three ounces of the dilute acid are poured in upon the hyposulphite, after which the cork is immediately replaced.

Sulphurous acid is now evolved by the action of the acid on the hypo, and as the gas is generated it is led as a series of bubbles through the water in the bottle B as shown. The air space above the water in bottle B soon becomes filled by displacement with sulphurous acid gas, which is a little over twice as heavy as air; so in order to expedite the complete saturation of the water, it is convenient to remove the bottle A with its tube from bottle B, and after having closed the latter by its cork or stopper, to agitate it thoroughly by turning the bottle upside down. As the sulphurous acid gas accumulated in the air space over the water is absorbed by the water, a partial vacuum is created, and when the stopper is eased an inrush of air may be noted. When, after passing fresh gas through the liquid for some minutes, no further inrush of air is noted on easing the stopper as before described after agitating the bottle, it may be concluded that the water is thoroughly saturated with sulphurous acid and is strong enough for immediate use. More gas can be generated by adding more dilute sulphuric acid to the hypo until the latter is decomposed; then it should be thrown aside, and a fresh charge put in the bottle. On preparing the solution it is well to set the bottles on the outside ledge of the window, or in some other open situation where no inconvenience will result from the escape of the excess of sulphurous gas as it bubbles through the water.

The solution of sulphurous acid, if preserved at all, ought to be kept in small bottles, completely filled and perfectly closed; but as it is very easy to saturate a considerable quantity of water with sulphurous acid gas in a short time, there is but little inducement to use a solution which may possibly have become weakened by keeping.

Care should be taken not to add too much dilute acid to the hypo at a time, else excessive effervescence will occur, and the solution will froth over the top of the bottle.

THE NATIONAL MONUMENT AT ROME.

The height and size of the monument were not determined on, nor was the exact location, and the competitors had full liberty in relation to the artistic character of the monument, and it was left for them to decide whether it should be a triumphal arch, a column, a temple, a mausoleum, or any other elaborate design. This great liberty given to the competitors was of great value and service to the monument commission, as it enabled them to decide readily what the character of the monument should be but it was a dangerous point for the artists, at which most of them foundered. The competition was resultless. Two prizes were given, but new designs had to be called for, which were governed more or less by a certain programme issued by the committee.

In place of the Piazza de Termini, a square extending from the church of St. Maria degli Angeli to the new Via Nazionale, to which preference was given by the competitors, the heights of Aracoeli were chosen. The monument was to be erected at this historic place in front of the side wall of the church, with the center toward the Corso, high above the surrounding buildings. The programme called for an equestrian statue of the King located in front of an architectural background which was to cover the old church walls, and was to be reached by a grand staircase.

Even the result of this second competition was not definite, but as the designers were guided by the programme, the results obtained were much more satisfactory. The commission decided not to award the first prize, but honored the Italian architects Giuseppi Sacconi and Manfredo Manfredi, and the German Bruno Schmitz, with a prize of ,000 each; and requested them to enter into another competition and deliver their models within four months, so as to enable the commission to come to a final decision. On June 18, the commission decided to accept Sacconi's design for execution, and awarded a second prize of ,000 to Manfredi.

Manfredi's design shows a handsomely decorated wall in place of the gallery, and in front of the wall an amphitheater is arranged, in the center of which the equestrian statue is placed. Bruno Schmitz' design shows a rich mosaic base supporting an Ionic portico, from the middle of which a six column Corinthian "pronaos" projects, which no doubt would have produced a magnificent effect in the streets of Rome.

ON THE EVOLUTION OF FORMS OF ORNAMENT.

The statement that modern culture can be understood only through a study of all its stages of development is equally true of its several branches.

Let us assume that decorative art is one of these. It contains in itself, like language and writing, elements of ancient and even of prehistoric forms, but it must, like these other expressions of culture, which are forever undergoing changes, adapt itself to the new demands which are made upon it, not excepting the very arbitrary ones of fashion; and it is owing to this cause that, sometimes even in the early stages of its development, little or nothing of its original form is recognizable. Investigations the object of which is to clear up this process of development as far as possible are likely to be of some service; a person is more likely to recognize the beauties in the details of ornamental works of art if he has an acquaintance with the leading styles, and the artist who is freed from the bondage of absolute tradition will be put into a better position to discriminate between accidental and arbitrary and organic and legitimate forms, and will thus have his work in the creation of new ones made more easy for him.

Hence I venture to claim some measure of indulgence in communicating the results of the following somewhat theoretical investigations, as they are not altogether without a practical importance. I must ask the reader to follow me into a modern drawing-room, not into one that will dazzle us with its cold elegance, but into one whose comfort invites us to remain in it.

The simple stucco ceiling presents a central rosette, which passes over by light conventional floral forms into the general pattern of the ceiling. The frieze also, which is made of the same material, presents a similar but somewhat more compact floral pattern as its chief motive. Neither of these, though they belong to an old and never extinct species, has as yet attained the dignity of a special name.

The walls are covered with a paper the ornamentation of which is based upon the designs of the splendid textile fabrics of the middle ages, and represents a floral pattern of spirals and climbing plants, and bears evident traces of the influence of Eastern culture. It is called a pomegranate or pine-apple pattern, although in this case neither pomegranates nor pine-apples are recognizable.

Similarly with respect to the pattern of the coverings of the chairs and sofas and of the stove-tiles; these, however, show the influence of Eastern culture more distinctly.

The carpet also, which is not a true Oriental one, fails to rivet the attention, but gives a quiet satisfaction to the eye, which, as it were, casually glances over it, by its simple pattern, which is derived from Persian-Indian archetypes , and which is ever rhythmically repeating itself .

The floral pattern on the dressing-gown of the master of the house, as well as on the light woolen shawl that is thrown round the shoulders of his wife, and even the brightly colored glass knicknacks on the mantel-piece, manufactured in Silesia after the Indian patterns of the Reuleaux collection, again show the same motive; in the one case in the more geometrical linear arrangement, in the other in the more freely entwined spirals.

Now you will perhaps permit me to denominate these three groups of patterns that occur in our new home fabrics as modern patterns. Whether we shall in the next season be able, in the widest sense of the word, to call these patterns modern naturally depends on the ruling fashion of the day, which of course cannot be calculated upon .

I beg to be allowed to postpone the nearer definition of the forms that occur in the three groups, which, however, on a closer examination all present a good deal that they have in common. Taking them in a general way, they all show a leaf-form inclosing an inflorescence in the form of an ear or thistle; or at other times a fruit or a fruit-form. In the same way with the stucco ornaments and the wall-paper pattern.

The Cashmere pattern also essentially consists of a leaf with its apex laterally expanded; it closes an ear-shaped flower-stem, set with small florets, which in exceptional cases protrude beyond the outline of the leaf; the whole is treated rigorously as an absolute flat ornament, and hence its recognition is rendered somewhat more difficult. The blank expansion of the leaf is not quite unrelieved by ornament, but is set off with small points, spots, and blossoms. This will be thought less strange if we reflect on the Eastern representations of animals, in the portrayal of which the flat expanses produced by the muscle-layers are often treated from a purely decorative point of view, which strikes us as an exaggeration of convention.

One cannot go wrong in taking for granted that plant-forms were the archetypes of all these patterns. Now we know that it holds good, as a general principle in the history of civilization, that the tiller of the ground supplants the shepherd, as the shepherd supplants the hunter; and the like holds also in the history of the branch of art we are discussing--representations of animals are the first to make their appearance, and they are at this period remarkable for a wonderful sharpness of characterization. At a later stage man first begins to exhibit a preference for plant-forms as subjects for representation, and above all for such as can in any way be useful or hurtful to him. We, however, meet such plant-forms used in ornament in the oldest extant monuments of art in Egypt, side by side with representations of animals; but the previous history of this very developed culture is unknown. In such cases as afford us an opportunity of studying more primitive though not equally ancient stages of culture, as for instance among the Greeks, we find the above dictum confirmed, at any rate in cases where we have to deal with the representation of the indigenous flora as contradistinguished from such representations of plants as were imported from foreign civilizations. In the case that is now to occupy us, we have not to go back so very far in the history of the world.

The deciphering and derivation of such forms as these is naturally enough more difficult; in the case of most of them we are not even in possession of the most necessary preliminaries to the investigation, and in the case of others there are very important links missing . In proportion as the representation of the plant was a secondary object, the travesty has been more and more complete. As in the case of language, where the root is hardly recognizable in the later word, so in decorative art the original form is indistinguishable in the ornament. The migration of races and the early commercial intercourse between distant lands have done much to bring about the fusion of types; but again in contrast to this we find, in the case of extensive tracts of country, notably in the Asiatic continent, a fixity, throughout centuries, of forms that have once been introduced, which occasions a confusion between ancient and modern works of art, and renders investigations much more difficult. An old French traveler writes: "J'ai vu dans le tr?sor d'Ispahan les vetements de Tamerlan; ils ne different en rien de ceux d'aujourd'hui." Ethnology, the natural sciences, and last, but not least, the history of technical art are here set face to face with great problems.

In the case in point, the study of the first group of artistic forms that have been elaborated by Western art leads to definite results, because the execution of the forms in stone can be followed on monuments that are relatively not very old, that are dated, and of which the remains are still extant. In order to follow the development, I ask your permission to go back at once to the very oldest of the known forms. They come down to us from the golden era of Greek decorative art--from the fourth or fifth century B.C.--when the older simple styles of architecture were supplanted by styles characterized by a greater richness of structure and more developed ornament. A number of flowers from capitals in Priene, Miletus, Eleusis, Athens , and Pergamon; also flowers from the calathos of a Greek caryatid in the Villa Albani near Rome, upon many Greek sepulchral wreaths, upon the magnificent gold helmet of a Grecian warrior --these show us the simplest type of the pattern in question, a folded leaf, that has been bulged out, inclosing a knob or a little blossom . This is an example from the Temple of Apollo at Miletus, one that was constructed about ten years ago, for educational purposes. Here is the specimen of the flower of the monument to Lysicrates at Athens, of which the central part consists of a small flower or fruits .

The form passes over into Roman art. The larger scale of the buildings, and the pretensions to a greater richness in details, lead to a further splitting up of the leaf into acanthus-like forms. Instead of a fruit-form a fir-cone appears, or a pine-apple or other fruit in an almost naturalistic form.

Such remains of pictorial representation as are still extant present us with an equally perfect series of developments. The splendid Graeco-Italian vessels, the richly ornamented Apulian vases, show flowers in the spirals of the ornaments, and even in the foreground of the pictorial representations, which correspond exactly to the above mentioned Greek relief representations.

The Pompeian paintings and mosaics, and the Roman paintings, of which unfortunately very few specimens have come down to us, show that the further developments of this form were most manifold, and indeed they form in conjunction with the Roman achievements in plastic art the highest point that this form reached in its development, a point that the Renaissance, which followed hard upon it, did not get beyond.

Thus the work of Raphael from the loggias follows in unbroken succession upon the forms from the Thermae of Titus. It is only afterward that a freer handling of the traditional pattern arose, characterized by the substitution of, for instance, maple or whitethorn for the acanthus-like forms. Often even the central part falls away completely, or is replaced by overlapping leaves. In the forms of this century we have the same process repeated. Schinkel and Botticher began with the Greek form, and have put it to various uses; Stuler, Strack, Gropius, and others followed in their wake until the more close resemblance to the forms of the period of the Renaissance in regard to Roman art which characterizes the present day was attained .

Now, what plant suggested this almost indispensable form of ornament, which ranks along with the acanthus and palmetta, and which has also become so important by a certain fusion with the structural laws of both?

The inflorescence corresponds almost exactly to the ornament, but the multipartite leaf has also had a particular influence upon its development and upon that of several collateral forms which I cannot now discuss. The shape of the leaf accounts for several as yet unexplained extraordinary forms in the ancient plane-ornament, and in the Renaissance forms that have been thence developed. It first suggested the idea to me of studying the plant attentively after having had the opportunity five years ago of seeing the leaves in the Botanic Gardens at Pisa. It was only afterward that I succeeded in growing some flowers which fully confirmed the expectations that I had of them .

The leaf in dracunculus has a very peculiar shape; it consists of a number of lobes which are disposed upon a stalk which is more or less forked . If you call to your minds some of the Pompeian wall decorations, you will perceive that similar forms occur there in all possible variations. Stems are regularly seen in decorations that run perpendicularly, surrounded by leaves of this description. Before this, these suggested the idea of a misunderstood perspective representation of a circular flower. Now the form also occurs in this fashion, and thus negatives the idea of a perspective representation of a closed flower. It is out of this form in combination with the flower-form that the series of patterns was developed which we have become acquainted with in Roman art, especially in the ornament of Titus' Thermae and in the Renaissance period in Raphael's work.

The attempt to determine the course of the first group of forms has been to a certain extent successful, but we meet greater difficulties in the study of the second.

It is difficult to obtain a firm basis on which to conduct our investigations from the historical or geographical point of view into this form of art, which was introduced into the West by Arabico-Moorish culture, and which has since been further developed here. There is only one method open to us in the determination of the form, which is to pass gradually from the richly developed and strongly differentiated forms to the smaller and simpler ones, even if these latter should have appeared contemporaneously or even later than the former. Here we have again to refer to the fact that has already been mentioned, to wit, that Oriental art remained stationary throughout long periods of time. In point of fact, the simpler forms are invariably characterized by a nearer and nearer approach to the more ancient patterns and also to the natural flower-forms of the Araceae. We find the spathe, again, sometimes drawn like an acanthus leaf, more often, however, bulged out, coming to be more and more of a mere outline figure, and becoming converted into a sort of background; then the spadix, generally conical in shape, sometimes, however, altogether replaced by a perfect thistle, at other times again by a pomegranate. Auberville, in his magnificent work "L'Ornement des Tissus," is astonished to find the term pomegranate-pattern almost confined to these forms, since their central part is generally formed of a thistle-form. As far as I can discover in the literature that is at my disposal, this question has not had any particular attention devoted to it except in the large work upon Ottoman architecture published in Constantinople under the patronage of Edhem Pasha. The pomegranate that has served as the original of the pattern in question is in this work surrounded with leaves till it gives some sort of an approach to the pattern. Whoever has picked the fruit from the tender twigs of the pomegranate tree, which are close set with small altered leaves, will never dream of attributing the derivation of the thorny leaves that appear in the pattern to pomegranate leaves at any stage of their development.

It does not require much penetration to see that the outline of the whole form corresponds to the spathe of the Araceae, even although in later times the jagged contour is all that has remained of it, and it appears to have been provided with ornamental forms quite independently of the rest of the pattern. The inner thistle-form cannot be derived from the common thistle, because the surrounding leaves negative any such idea. The artichoke theory also has not enough in its favor, although the artichoke, as well as the thistle, was probably at a later time directly pressed into service. Prof. Ascherson first called my attention to the extremely anciently cultivated plant, the safflor , a thistle plant whose flowers were employed by the ancients as a dye. Some drawings and dried specimens, as well as the literature of the subject, first gave me a hope to find that this plant was the archetype of this ornament, a hope that was borne out by the study of the actual plant, although I was unable to grow it to any great perfection.

In the days of the Egyptian King Sargo this plant was already well known as a plant of cultivation; in a wild state it is not known . In Asia its cultivation stretches to Japan. Semper cites a passage from an Indian drama to the effect that over the doorway there was stretched an arch of ivory, and about it were bannerets on which wild safran was painted.

The importance of the plant as a dye began steadily to decrease, and it has now ceased to have any value as such in the face of the introduction of newer coloring matters . Perhaps its only use nowadays is in the preparation of rouge .

But at a time when dyeing, spinning, and weaving were, if not in the one hand, yet at any rate intimately connected with one another in the narrow circle of a home industry, the appearance of this beautiful gold-yellow plant, heaped up in large masses, would be very likely to suggest its immortalization in textile art, because the drawing is very faithful to nature in regard to the thorny involucre. Drawings from nature of the plant in the old botanical works of the sixteenth and seventeenth centuries look very like ornamental patterns. Now after the general form had been introduced, pomegranates or other fruits--for instance, pine-apples--were introduced within the nest of leaves.

Into the detailed study of the intricacies of this subject I cannot here enter; the East-Asian influences are not to be neglected, which had probably even in early times an effect upon the form that was assumed, and have fused the correct style of compound flowers for flat ornament with the above-mentioned forms, so as to produce peculiar patterns; we meet them often in the so-called Persian textures and flat ornaments .

We now come to the third group of forms--the so-called Cashmere pattern, or Indian palmetta. The developed forms, which, when they have attained their highest development, often show us outlines that are merely fanciful, and represent quite a bouquet of flowers leaning over to one side, and springing from a vessel , must be thrown to one side, while we follow up the simpler forms, because in this case also we have no information as to either the where or the when the forms originated.

Here again we are struck by resemblances to the forms that were the subjects of our previous study, we even come across direct transitional forms, which differ from the others only by the lateral curve of the apex of the leaf; sometimes it is the central part, the spadix, that is bent outward, and the very details show a striking agreement with the structure of the aroid inflorescence, so much so that one might regard them as actually copied from them.

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