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82 THE PHOTOGRAPHIC NEWS. LFEBRUARY 6, 1885. THE WENHAM GAS LAMP. In the days of wet collodion the idea of photography by the light of gas or that of an oil lamp would have been considered a very wild one, but the gelatino-bromide pro cess has changed all that; and instead of looking upon a gas flame as being next door to non-actinic from an every day worker’s point of view, it is nothing extraordinary for a photographer to regularly make portrait negatives and also his prints by gas light. Nearly five years ago (1880, p. 338) an account was given in the Photographic News of a visit to the studio of Mr. P. M. Laws at Newcastle-upon-Tyne, and our readers will remember how, by the aid of a Wigham burner of sixty-eight jets, Mr. Laws found no difficulty in making a carte negative with an exposure of eight seconds, or a cabinet negative in sixteen seconds. Mr. Law's simply uses a reflector something like a large Dutch oven lined with strips of mirror, and to diminish the glare he passes the light through a screen consisting of strips of blue glass set in a frame. Mr. F. H. Wenham, who is not only known as one of the early photographic workers, but as a pioneer in many im portant branches of industry, has recently devised a form of gas lamp by which a very much increased return of light can be obtained for the gas burned; and what is, perhaps, of more importance from a photographic point of view, the light is far whiter than when the gas is burned at any ordinary jet. The essential characteristic of the Wenham lamp is the heating of the air and gas before they react upon each other, and the following sectional diagram will show how A, air inlet; B, regenerator ; C, cylinder to convey heated air to burner through perforated discs; D, burner; E, flame; F, reflector; G, ring fastener; H, hinge ; J, ring to support dish ; K, glass dish ; L, chimney; M, gas supply pipe; N, heat disperser. the system is carried out. The part marked in the dia gram as the regenerator is a channelled and perforated plate of cast iron, which becomes considerably heated, and through the passages of which the air passes before reach ing the burner. The gas is warmed to some extent in passing through the tube, M, but still more during its passage through the part of the apparatus immediately over the burner, D ; the gas duct branching out into seve ral tubes at this point, and all of these tubes are in the stream of hot air as it comes from the cast iron regenera tor. A few data as to the performance of the lamp in com parison with an Argand burner will be interesting. Taking the light at an angle of 45 degrees with the vertical line, it was found that, in the case of the smaller Wenham lamp, a light equal to eight and a-half standard candles was obtained for each cubic foot of gas burned per hour; while, with the larger lamp, a much greater economy is realised, the light amounting to over eleven standard candles for each cubic foot of gas burned per hour. A trifle over two and a-half candles (2'6) is the re turn of light obtainable when gas (in each instance ordinary London gas, of 16-candle power for a burning rate of five feet per hour is referred to) is burned at an ordin ary argand burner. These results, which are the outcome of determinations made by Dr. Hopkinson, Mr. George Livesey, and Mr. F. W. Hartley, show a gain in lighting power of about four-fold by the use of the new burner: rather under four-fold in the case of the smaller size, and nearly five-fold in the case of the largest size. As far as we know, no exact trials have yet been made to determine the suitability of the light of the Wenham lamp for portraiture, but judging from a rough experiment made with Warnerke's actinometer, we should estimate that by using four of the large lamps with suitable re flectors, it would be possible to obtain a full-length portrait in from five to six seconds. The external appearance of the lamp may vary according to circumstances, but it is essentially a suspension lamp, and the following cut will give a good notion of a usual form, A being the stopcock regulating the supply of gas. For studio use the lamps might well hang on light cranes, the connection with the permanent gas fittings being made by flexible pipes. For printing on the new rapid paper, the lamp in ques tion appears to be extremely well adapted, as a large number of printing frames can be laid on a table so as to receive the unobstructed radiations from tbe lamp. It is also interesting to note that the production of prints on ordinary albumenized paper by the lamp in question is not altogether an impossibility, but an exposure of about twelve hours would probably be required.