« PředchozíPokračovat »
The union of these two discoveries so accelerated the process as to render it no longer difficult to take portraits from life with every description of camera. Thus, we find that salts of silver, which, when used by themselves, were but little affected by light, greatly accelerated the most sensitive of homogeneous preparations. Mr. Talbot reduced his salts of silver either to a chloride or a bromide, to prevent the further action of light, and yet either or both of these when mixed in small quantities with preparations previously regarded as being very sensitive, were found to quicken the process to a very considerable extent. With the discoveries of Goddard and Claudet the Daguerreotype process attained its greatest progress, as far as the quickness of the process is concerned. It has, however, connected with it, some objection that further stimulated the Photographer to pursue the science in other directions. The Daguerreotype picture was unsuited for various purposes, to which photography is now applied. The reflection from those parts representing shade, requires that the tablet should be held at a certain angle to the line from which the light proceeds. They are unsuitable for being introduced into books or albums.
About the same time I succeeded in taking photographs on glass, but the process was slow and tedious, because no developing process unconnected with Daguerreotype had yet been discovered.*
Next to Daguerre, Mr. Fox Talbot introduced the develop
In the Manual of Photography, page 94, Professor Hunt thus describes my process:-"Mr. Towson employed glass plates, prepared in this manner, with "much success. The mode adopted by that gentleman was, to have a box the "exact size of the plate, in the bottom of which was a small hole; the glass was "placed over the bottom, and the mixed solution, just strong enough to be milky, "of salt and silver poured in. As the fluid finds its way slowly around the edges "of the glass, it filters out, separating the fine precipitate which is left behind "on the surface of the plate." I may add that this precipitate, when dry, adheres firmly to the surface of the glass; which, previously to being placed in the camera, was dipped into a bath of a solution of nitrate of silver.
ing process. In 1841 he invented the Calotype, which at that period, next to Daguerreotype, was the most sensitive; but Calotype, as it now exists, has been improved by the discoveries of Mr. Cundell, whose process appeared in the London and Edinburgh Philosophical Magazine for May, 1844. About the same time Hunt discovered his Ferrotype, which to a considerable extent has brought down the science of Photography to the present day.
The great value of this discovery was the developing power of the photosulphate of iron. This, notwithstanding the improvements that have been discovered during the subsequent twenty years, still remains in use and may be regarded as one of the greatest discoveries in connexion with Photography, as it is now in practice, that was made at that early period.
The prepared paper on which positive photographs are now printed from the negative, may be regarded as amongst the earliest of those practised by the English School of Photography. Fox Talbot in 1834 prepared a paper very similar to those now in use for printing from negatives; and when in 1839 the hyposulphite of soda was employed for the purpose of fixing the picture, little remained for future discovery, except by varying the solution, by which the paper is prepared, so as to quicken the process and improve the tone of colour, and the manufacture of paper expressly for photographic purposes.
Since the period we have referred to in this paper, great progress has, however, been made in producing negatives of far greater value than any of those known at that period. These improvements have principally been founded on the use of collodion, the invention of Mr. Archer and Mr. Fry.*
It is greatly to be regretted that we cannot determine whether the collodion process had its origin with Fry or Archer. This defect in the history of the discoveries made subsequently to those described in this paper, arose from the fact that neither Archer nor Fry published his invention until after it had been practised by others. It is, however, very probable that both these gentlemen made this discovery independent of each other.
In this paper it has not been attempted to enter into any details, but merely to trace the foundation of Photography, which was laid in the five years commencing with 1839, after which period I have had but little practical acquaintance with the science.
The history of the progress of the science and the art of Photography, affords a striking illustration of the gradual manner in which many interesting discoveries are developed. After the publication of the discoveries of Daguerre, for a short period a feeling of universal astonishment was excited. But this gradually subsided; whilst, at the same time, Photography, as a science, was progressing. In 1850 the writer of the article, Photogenic Drawings," in the Penny Cyclopædia says, "Now that the first novelty has worn off, “the interest taken by the public in the discovery has greatly "diminished." Six years subsequently, in the supplement to the same work, after describing the progress that had since been attained, the writer remarks,† "Of an art so new, it would be "premature to attempt to enumerate the advantages." And so to the present time, new appliances of the art are continually being brought into operation; and we may now say that there scarcely exists a family within the pale of the civilized members of the human race, that is not, to some extent, indebted to the Photographic art. Several sciences have also received its aid, Astronomy and Archæology amongst the number; and from time to time we still hear of some new application of this valuable and interesting art. As a science its resources have been more slowly developed, but may ultimately be found of equal value.
See volume xviii, page 113.
+ See first supplement, article " Photography," volume xii, page 420.
CUP-CUTTINGS AND RING-CUTTINGS
ON THE CALDER STONES NEAR LIVERPOOL.
By Professor J. Y. Simpson, M.D. (Edinburgh),
(READ 12TH JANUARY, 1865.)
LATELY the attention of archæologists has been strongly called to cup and ring sculpturings on stones and rocks in various parts of Great Britain and Ireland. The lapidary surfaces are not smoothed or hewn in any way to receive the sculpturings. The sculpturings themselves consist of incised cuttings of various forms. The principal or generic types, however, hitherto observed are the following:
1. Hollow rounded excavations or cups-varying from one to three or four inches in diameter; but shallow in proportion to their breadth.
2. Cups of the preceding type encircled by one incised ring. 3. Cups surrounded by a series of concentric and enlarging complete rings.
4. Cups with an enclosing ring or series of rings but the rings rendered incomplete by a straight radial groove or channel traversing them from the centre to the circumference. 5. Similar series of concentric rings without a central cup;
6. Series of encircling rings made by a spiral line or volute. These lapidary archaic cuttings have now been found in many different localities; and in some localitics in great abundance. On rocks and monoliths on the banks of the Add in Argyllshire, I have counted nearly two hundred ring and cup cuttings, in a district about six or eight miles long and two or three miles in breadth. Above three hundred groups
of the lapidary circles have been discovered within the last few years within the county of Northumberland alone.
The cup and ring cuttings have been discovered in a variety of relations or positions. I have seen them sculptured on the surfaces of rocks in situ; on large stones placed inside and outside the walls of old British cities and camps; on blocks used in the construction of the olden dwellings and strongholds of archaic living man; on the interior of the chambered sepulchres and kistvaens of the archaic dead; on monoliths and on cromlechs; and repeatedly in Scotland on megalithic or so-called "Druidical" circles.
The Calder Stones near Liverpool afford a very interesting and remarkable example of these cup and ring carvings upon this last variety of stones-or, in other words, upon the stones of a small megalithic circle. Some of the Calder Stones afford ample evidence of modern chiselling, as remarked by its sharpness and outray figurings. But in addition to these there are cut upon them-though in some parts greatly faded away-sculpturings of cups and concentric rings exactly similar to those existing in various parts of England and Scotland. These archaic carvings upon the Calder Stones are remarkable not only from their perfect and entire similarity to the sculptures found elsewhere; but still more so from the fact that we have here presented upon a single circle, almost every known and recognised type of these cuttings; thus affording one strong proof among many others that the cup and ring cuttings are all of one class of art and of one origin, though somewhat diverse in form and type.
The Calder circle is about six yards in diameter. It consists of five stones which are still upright, and one that is fallen.
I have received, for example, from my friend Dr. Wyse, a sketch of a sculptured stone obtained from an ancient "weem or underground house in Forfarshire, where some of the lapidary circles are so precisely similar in appearance to those on the inner surface of the largest Calder Stone, that, though the two stones are hundreds of miles apart, they look as if they had been carved by the same hand, and had met, too, with the same form of disintegration.