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Ue Pqotogruphir Achs, Mlobember 5, 1880. PHOTOGRAPHY IN AND OUT OF THE STUDIO. PzoroarapuINQ by ARTIVICIAL Light—PHOSPHORESOENCE and FLUOREOENCE—Actinometers. Photoriraphing by Artificial Light.—Dining the dismal weather we have had for m arly two months, the thoughts of most photographers must have turned to the question of the possibility of a ready and economical means of producing photographs by artificial light. There are hosts of methods, it is true, from the electric light down to the “secret” by which, for the small sum of twenty-four stamps, the inventor will divulge the process and guarantee its perfect success. The Luxograph light is being worked commercially, and so is ordinary gas, as effectually demonstrated by Mr. Laws. Still the mass of photographers know very little about the powers of artificial lights, though it is within the experience of everycne that something of the kind would be an inestim able boon and “put money in the purse.” The success which has attended the technical meetings of the South London Photographic Society suggests that an evening might be profitably spent in the demonstration of the possi bility of using artificial light in an ordinary photographic business. A few weeks ago we gave a description of Mr. J. W. Swan’s electric lamp, and since then Mr. Swan has de livered a most interesting lecture on the subject. In the description which we gave of Mr. Swan’s lamp, the illumi nating material was incandescent carbon. Carbon, however, has always had the drawback of a too-ready combustibility, and therefore experimenters have always sought to substitute some other substance. We notice that Mr. Swan in his lecture stated that he now uses a better material than car bonised cardboard. An advance has distinctly been made, as Mr. Swan, with his usual deliberate care, can be relied upon as one who would not make a statement publicly unless he were prepared to verify it. London photographers, we are certain, are anxious to know something practically of Mr. Swan’s electric lamp, and certainly if artificial light is needed anywhere, it is needed in the most smoky city in the world. If it bo not possible to have a “ technical ” meeting of the kind we have suggested above, could not Mr. Swan be persuaded to deliver his lecture before the Photo graphic Society ? The interest felt in the subject is intense, and we can safely prophecy a crowded attendance. Phosphorescence and Fluorescence.—The phenomena of the fluorescence and phosphorescence of certain substances, such as Balmain’s paint, are not clearly understood, but recent experiments would go to show that, while few sub stances phosphoresce— that is to say, retain and emit the light imparted to them—nearly every substance is capable of fluorescing, though the rays given forth may be so faint as to be practically invisible. Mr. Lewis Wright, in a series of interesting letters which have appeared in a scientific contemporary, draws attention to this point, and goes on to say that phosphorescence, as shown by Balmain’s paint, ought to be clearly linked with fluoresence, a coincidence which was felt to be necessary by Becquerel, who constructed a “ phosphoscope,” by which the illumi nated fluorescent substance can be rapidly removed from the light ; he thus found they retained luminosity for a calculable time. Mr. Wright further alludes to Pro fessor Tyndall’s experiments on the subject, and describes an apparatus by which fluorescence and phosphorescence were clearly demonstrated to be united. This apparatus consisted of a square iron lantern, which had on one side a perpendicular slit reaching from the bottom almost to the top of the lantern. Outside the slit was mounted, on axles, a cylinder driven by a grooved pulley and stout cords forming a double system of multiplying wheels, so as to give swift rotation. This cylinder was painted with ura nium the saltsof which fluoresce green, and made to revolve rapidly, the light coming through the slit being supplied by the electric light, though, as Mr. Wright points out, the magnesium light would do nearly as well. It is obvious that a person standing on what, for the sake of explanation, may be called the reverse side of the revolving cylinder, would, supposing it were not phosphorescent, find it per fectly dark, simply because it would act as a screen in cut ting off the light comirg through the slit. This, however, is not the case. The cylinder, under these circumstances, becomes perfectly luminous, giving forth the characteristic green light. Thus, as the writer of the letters remarks, fluorescence is linked on to phosphorescence, and though all fluorescent substances will not show this, with our present experimental means there can be little doubt that it is only a question of degree and of powers of observa tion. The subject is certainly a very fascinating one, and is well worthy of investigation. By the way, what has become of Balmain’s paint? The experiments made were wonderfully successful, but has any real practical use been made of it ? The experience of any one who has put it to practical use would be worth hearing. Actinometers.—A valuable hint to those who use actino meters is conveyed in the experiments of Mace andNicati, who, a few monthsago, indicated to the French Academy a method of comparing lights of different colours as to in tensity. From a series of experiments they have now come to the following conclusions :—1. In all cases, the maximum intensity in the solar spectrum is in the yellow—very near line D (as generally accepted). The intensity decreases very quickly on either side of this point. 2. The percep tion of blue and violet diminishes much more slowly, with diminished illumination, than that of less refrangible colours. Also, from the extreme red to the green of wave length about 0-5 inches, the law of distribution of inten sity remains absolutely the same, whatever the illumi nation (green being merely observational). 3. Between eyes equally capable of discerning colours there are very sensible differences. The last proposition is the one to which we would draw attention. In the use of all actino meters dependent upon gradations of tint or varying in tensity of light, the differences which exist in the human eye must always be borne in mind. Of course, if an accu rate scale be set up in the first instance, by experiment, these differences are not of much importance. But it is evident that no experience of one person can be said to re present that of another, and hence the necessity of per sonal calculation when using actinometers. o At Nome, AT SARONY SQUARE, SCARBOROUGH. A journey of nearly 500 miles, undertaken for the sole pur pose of visiting a studio, is no little matter, even in these days of fast through trains and comfortable carriages; but we may say at the outset that a peep at the Sarony estab lishment at Scarborough is well worth a few hours’ hard travelling. In any case, we fear it would be hopeless to enlist the sympathies of the reader in our behalf; for, after all, a couple of days spent at the queen of watering- places during warm autumn weather, just as the outbursts of sunshine are getting few and far between, and it behoves one to make the most of them, can scarcely be termed a grave hardship. We shall say nothing, therefore, of our swift journey down north, of a two hours’ halt at York for dinner, and a peep at the Minster ; its massive roof so clearly lit that every trait and niche in the white stone is plainly visible, and its magnificent windows—espe cially “ The Five Sisters of York,” endeared to us by Dickens’ charming legend—which are among the finest in the world. Nor shall we enlarge on our first glance at Scarborough, as we looked down upon it at night, from the high cliffs, and saw below the glittering lights of the Spa Gardens, the curved quay studded with lanterns, the illumi nated bridge and grand hotel opposite and far away at th®