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pin-hole, and therefore the intensity of the light from the sun’s disc was equal to (126 X 420) about 53,000 times that of a candle-flame. This is more than three times the value found by Arago for the intensity of the light from the sun’s disc as compared with that from a candle-flame; so much for a Glasgow December sun! The '09 cm. diameter of the pin-hole, of the Glasgow obser vation, subtends," at 230 centimetres distance, an angle of 1'2556 of a radian ; which is 23'7 times the sun’s diameter (1/108 of a radian). But at 230 cm. distance the sunlight through the pinhole amounted to 126 times the York moonlight (which was 1 candle at 233 cm. distance). Hence the Glasgow sunlight was [(23-7)2 X 126 times or] 71,000 times the York moonlight. We cannot, therefore, be very far wrong in esti mating the light of full moon as about one-seventy-thousandth of the sunlight, anywhere on the earth. This, however, is a comparison which, because of the probably close agreement of the tints of the two lights, can probably be made with minute accuracy ; and we must therefore not be satisfied with so very rough an approximation to the ratio at this 70,000. A lime light, or magnesium light, or electric arc-light, carefully made and re-made with very exactly equal brilliance, for each separate observation of sunlight and moonlight, might be used, for intermediary. Zotes, Switzerland is to have a photographic exhibition this year; it will be open from May till September. Dr. Liesegang has favoured us with an early copy of his new edition of “ Die Bromsilber Gelatine.’’ The work has been most carefully prepared, and is well up to date. A goodly collection of photographs connected with pisciculture will form part of the International Fisheries Exhibition which is to be opened at South Kensington on May 12 by the Queen. The late Mr. Crawshay, of Cyfarthfa Castle, collected during his lifetime a most valuable series of photographs of trout and salmon in English rivers, which he presented, we remember, to Frank Buckland. This, if still complete, would be an interesting addition to the Fisheries Exhibition. MM. Goupil et Cie., of Paris, are said to have purchased a wonderful secret process—a wet collodion method, so we are told—which permits them to reproduce paintings in the camera far more perfectly than by the old method. Certainly, the copies of paintings recently issued by MM. Goupil represent magnificent photographic work ; still, we much doubt its being simply due to a modified collodion process. As photographers are more interested than most people in the sun, they may like to know some details of the working of a railway to that luminary, which Professor Young, of Princeton College, has calculated, en attendant the realisation of the scheme. He says: “ Take a railroad from the earth to the sun, with a train running 40 miles an hour, without stops, and it would take about 265 years and a little over to make the journey.” As to the fare, the learned Professor, calculating at the modest rate of a halfpenny per mile, estimates it at £193,700. You would have to be a millionaire, therefore, to take tickets for your wife and family. An entirely new explosive is said to have been used in damaging the Government Offices at Westminster, and as novel exploding agents appear regularly about once a week, we may be permitted to say that it is not the material, but only the name, that is new in nineteen cases out of twenty. Examined critically, the new explosive generally turns out to be the photographer’s old friend guncotton, or that insidious liquid nitro-glycerine, or a permutation or com bination of these two. And as nitro-glycerine and gun cotton are both nitro-compounds, and practically the same — the one being produced by the action of nitric acid on a solid (cotton), and the other by the action of nitric acid on a liquid (glycerine)—it follows that whatever the grandiose names invented for the novelties, they all turn on the same chemical pivot. One word more on the subject of the Westminster explosion. The whole affair has been most grossly exaggerated. Excepting the broken glass, which can scarcely be called a national calamity, the damage done amounts to the destruction of a stone window-sill, the wrecking of a small room in the basement, and serious damage to an apartment overhead. When we get news papers illustrated by photography which will let the public see the truth for themselves, we suspect the sensational articles in our dailies will be at a discount. Sometime back we described how M. Janssen proposed to employ photography to measure the light intensity of heavenly bodies, and we published, too, in these columns, a criticism on the method by Mr. Plener. M. Janssen judges of the luminosity by the density of the photographic image produced. The first results of the French astron omer have now been communicated to the Academy of Sciences, the light of the full moon, of the comet of 1881, &c., having been under examination. M. Janssen’s method is based on the principle of photometry, that the intensities of two light-sources are in the inverse ratio of the time they take to perform the same photographic work, or the time taken to produce the same depth of tint on two sensitive films of a like nature. In the last century, it was the parsons who were treated as menials, the chaplain, if permitted to dine at table, being expected to leave with the pudding. Now-a-days, apparently, it is the man with a scientific training who comes in for indignities, judging from the following advertisement, which the Chemiker Zeitung quotes, for an “academically-educated chemist, fully acquainted with the manufacture of sugar, who can undertake in summer coppersmith’s work, or supervise teams of draught oxen.” It is not so long ago that the Chemical News contained an advertisement for a capable man to undertake commercial analysis, and “ to wait at table.” We doubt the wisdom of making a small instantaneous camera in the form of a revolver, as M. Enjalbert has done. Of course a camera pistol is harmless enough in itself, but most people have got the idea into their heads that it is