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302 THE PHOTOGRAPHIC NEWS. [April 17, 1891. jet, which, as I mentioned before, had a. flat (slit-like) opening. So I at once ordered a pair of interchangeable jets suitable for the ether light. They arrived, and since that time the saturator, as well as the jets, have done their duty I never have a blow-up or a pop, and always get a very good light for polariscope and microscope. I learnt subsequently that Mr. Ives has also taken to the zig-zag circuit, but, if I am well informed, not before the year 1888, whereas I had already, towards the end of 1887, made a canal of this form to my tank. Ives’s patent, I am told, dates from 1882, and his im provement for the zig-zag from 1888. Scott’s saturators came out in 1890. If these dates are correct, neither of them can claim the priority of invention, either for the stuffed saturator or for the zig-zag canal on the one hand, nor for applying heat to the saturator on the other hand. Previous to them there was Herr von Kalkow, whose saturator was described in 1878, and I myself used a zig zag canal as early as 1887 on the top of a layer of porous material. I quote these dates as they may interest you, as I have no pecuniary interest in the matter at all. If the ether light is not generally used, I think it is in consequence of its being associated with that ill-bearing name, " mixed jet.” If so, help can be brought with very little loss of light. I have designed a bloiv-throwjh jet which is well adapted for the ether light. This same jet gives also a most brilliant light when two bags are used. It stands somewhat between the usual blow-through and the mixed jet, but two bags are necessary (see fig. 3). A and B are two ordinary nipples, of which A projects above B by about six millimetres (one-quarter inch). Both have equal bore of one millimetre (one-twenty-fourth of an inch). The A nipple makes an angle of 35°, and the B nipple one of 65° with the horizontal CD. From the point where the B nipple touches the A nipple, a small groove is worked into the under part of the A nipple, reaching to the point of the burner. I think it would be worth your while to have such a jet made, so that you could for yourself form an opinion of its merits. This form of jet is very advantageous for those demonstrators who would like a better light than is obtainable with the ordin ary blow-through, and yet would not like to use a mixed jet. With owe bag for the oxygen and the gas from the main supply the jet is not suitahle, but when two bags are used with a weight of one and a half hundredweight to begin with, the jet gives a light very near to that by the ordinary mixed jet. I should very much like to see such a jet worked with two cylinders, of which, as yet, I have no experience. With the ether the jet is safer than the mixed jet, be cause the vapour and the oxygen are kept separate till the igniting point is reached, and another advantage is that the peculiar construction causes the hydrogen element to heat the oxygen nipple, and the heated oxygen increases the intensity of the light. CRYSTAL PALACE INTERNATIONAL PHOTO GRAPHIC EXHIBITION. First Notice. Tins Exhibition, which nominally opened on Monday last, was, after the manner of exhibitions, not nearly ready for public inspection on the opening day. Some of the apparatus stalls were unoccupied, while at others the tapping of hammers and screeching of planes told of fixtures not yet in a fixed position. So far as the apparatus section is concerned, the present Exhibition bears unfavourable comparison with that of two years ago, when from one end of the nave to the other the floor of the building was covered with the ex hibits of our foremost manufacturers. This year about one-sixth of the same space is occupied with apparatus, and, although one or two leading firms put in an appear ance, the majority are conspicuous by their absence. A visitor to the Exhibition held here in 1888 or 1889, and who afterwards came to that of 1891, might think that, perhaps, the trade had combined to boycot the scheme ; but such is not the case. It is a simple matter of that consideration of the three letters, £ s. d., towards which most things human have to filter down. In a word, the manufacturers say that it does not pay them to exhibit at Sydenham ; if it did, they would, of course, go there. But when goods have to be carried to and fro, an assistant taken from his ordinary work to be on duty at the Palace each day, and rent for space paid, there is little or no margin left for profit on any business which may be done. The Crystal Palace authorities would do well to look the matter fairly in the face, and see whether they cannot another year offer better inducements to our leading firms to exhibit their goods. To many people the apparatus is more attractive than the pictures, and they go to an ex hibition like this principally to see what novelties there may be in the market. Visitors to Sydenham this year who have such proclivities will most certainly be dis appointed; but it is as well to remember the salutary adage, “Audi alteram partem," and the other side say that if exhibitors would rent smaller spaces, and would take good care to put them in charge of pushing assistants, they would have no reason to regret their outlay. But although the apparatus is not as plentiful as one could wish, we may certainly say that never has a better collection of photographs been seen at the Crystal Palace ; and we are able to say this at a time when many of the pictures expected are not yet in their places; for, by an unfortunate misunderstanding, some two hundred pictures are detained at Liverpool. The date of the Palace Exhibition was so fixed that its opening should just tread on the heels of the closing day at the Liverpool Exhibition, so that many of the pictures shown at the latter place could be packed and sent to Sydenham direct. But this wise arrangement was suddenly knocked on the head by the resolve of the Liverpool people to keep the doors of their suecessful Exhibition open for an extra