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THE PHOTOGRAPHIC NHWS, Vol. XXIX. No. 1378.—January 30, 1885. CONTENTS. PAGE Printing by Electric Light 65 Heat Measurers and Photography 66 At Home.—“With Mr. Matthew Whiting at Wandsworth.”... 67 The Intensification of Gelatine Plates. By Arnold Spiller ...68 ’Cycling and Photography in Winter. By Henry Sturmey, Editorof “The’Cyclist.” 70 A Dictionary of Photography 71 Notes 71 Patent Intelligence 73 PAGE Notes of an Amateur Photographic Trip in 1884. By Matthew Whiting 74 A Portable Lamp for Tourists. By T. G. 75 Reflecting Telescopes for Photography. By A. Ainslie i Common 76 Correspondence 76 I Proceedings 78 I Talk 80 Answers to Correspondents 80 PRINTING BY ELECTRIC LIGHT. When, a few years ago, the question of the electric light came so prominently before the public, photographers— almost without exception—began to look forward with confidence to the halcyon days when they would be inde pendent of daylight for all photographic operations. How far their expectations have been fulfilled in this country is pretty well known. Portraiture by electric light is becoming an every-day affair. In the process of enlarging, the arc light is becoming more and more popular ; but as regards the ordinary work of printing little has been done, although it has, from time to time, been proved that a print on albumenized paper may be got by the aid of the electric light. Still, as each winter nears, and we in London are plunged into the gloom of never-ending fog, we cannot help turning eyes of yearning in the direction of the electric light, thinking of it in connection with print ing. That the same holds in Germany is shown by an article in a recent number of the Pholographische Wochen- Walt. Moreover, it is evident that the Editor of the Wochenblatt takes a tolerably hopeful view of the matter. We quote from the article referred to :— “ By any who consider how the light is reduced during our winter months, often for weeks together, by yellow fogs or thick clouds, it will not be denied that, particularly in our climate, there will in the future be many establishments set apart for the sole purpose of printing or photographic copying by the electric light.’’ If the Editor of the Wochenblatt imagines that he can 1'4 for Germany a monopoly of “ yellow fogs or thick clouds, we think he is vastly mistaken. We have always considered that London excelled in that particular direction. It may be remembered that, in treating of the subject of silver printing by the electric light in the News some time ago, we mentioned that we had found difficulty from the fact that, if we placed the printing-frame so near the light that printing went on tolerably rapidly, the heat was great. This fact is borne out by the Editor of the Wochenblatt, who says that in experiments which he had made, when “ the printing-frame was brought to a distance of one metre from an arc light, the heat was so great that, not only was there danger of the breaking of the negative, but that many kinds of varnish were so softened that the print stuck fast to the negative.” Herr Himley has recently been experimenting in various ways with a view to overcoming the difficulty of the excessive heating referred to, and the article in the Wochenblatt, which we have already mentioned, is chiefly taken up with accounts of these experiments. An inte resting table is given wherein are shown the results as regards time taken, for printing and incret se of tempera ture when, on the one hand, there is used a white reflector with matt surface, on the other Herr Hauptmann Himley’s “ diffuser.” W e can scarcely afford space to reproduce the table as it stands, but we may briefly sum up the results which it shows. The experiments were all performed at the distance of one metre from the light. The actinic strength of the light was estimated by Vogel’s photometer, freshly sensi tized albumenized paper being used, all pieces for testing being cut from the same sheet. In the first set of experiments with the reflector a single arc light giving “ at the most favourable estimate ” 1,200 candle light, and absorbing 2 hp., was used. In the second set, with the diffuser, two lights, giving each the same candle power as that used in the first, and each absorb ing the same power, were used. With the single light and the reflector the time required to bring out No. 17 on the photometer was 80 minutes. In the meantime the temperature at the photometer was raised through nearly 20° Fahr. With the double light and the “ diffuser ” the time taken to get the same number on the photometer was 145 minutes, whilst the temperature waa raised through only 449 F. Comparing the results to be seen here with those got with what is described as “ exceptionally good winter day light,” we find that in the case of the sunlight 18± on the photometer was brought out with an exposure of 95 minutes. From this we may assume that with an arc light of, say, 1,000 candles and a white reflector, we may print at a dis tance of a metre about as rapidly as in very good sunlight in winter. Comparing again the results got with the reflector and the diffuser, we see that, although heating is decreased by the diffuser more than proportionately to the actinism, the latter is also very materially reduced. In the exact proportion of 29 to 8, if we make allowance for the two lights in the one case, the one in the other. Against this we have to place the fact that the diffuser illuminates a considerably larger area than does the re flector. The reflector iliuminates, it appears, an area of only '96 square metres, whilst the diffuser illuminates an area of 288 square metres. If, therefore, our work is on so large a scale that we can make use of the whole area of nearly three square metres—somewhat over 30 square feet —we very nearly make up, in the case of the diffuser, by the extra number of the frames which we may place in the light, for the longer exposure which we have to give, while we have the advantages of a scarcely appreciable increase in temperature in place of a very decided heating. Himley’s “diffuser” is described and illustrated on page 5 of our present volume.