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546 THE PHOTOGRAPHIC NEWS. [AtGUST 28, 1885. lopment was much such an operation as toning ordinary prints. Fixing and washing were done much after the same fashion, and then the negatives were squeezeed down on very slightly oiled glass plates and allowed to dry, when they could be stripped off, and were quite flat. In order a soft paraflin (vaselin) is used, it suflices to merely rub a little on the back of the negative. All these yield satis factory prints, and there was nothing whatever in their appearance to indicate that the negatives had not been taken on glass plates. Before passing on to a detailed de scription of the roller slide, we may point out that each instrument is numbered, so that if any modification in the pattern should take place, the owner can get extra parts suited to his own slide by merely quoting the number. Figures 1 to 5 show some of the details of construction. F is the spool or roller, clothed with the stock of paper already wound on a wooden roller, the ends of this roller being so centred that it is quite impossible to put it in at the wrong end of the slide, or at the right end in a re versed position. H is the receiving roller or clamping spool, to which the free end of the paper is attached by a very simple device, and in running its course over the flat table, E, the paper actuates the two rollers, I and I', one of which acts as a measuring roller, and perforates the paper near the edges at each revolution. At each revolu tion of the measuring roller a distinct click takes place, this being provided for by a very simple piece of mechan ism, and when four ticks have been heard, one knows that all is ready for a fresh exposure. W and W are rollers which trail on the main spools, in order to prevent any escapement or unwinding of the paper while it is being manipulated with a free end. The general structure of the mechanism is built up on two light girders of cast brass, one of which is shown in plan by figure 3, while the frame system of two girders and the connecting pillars is connected to the back-board D by two pairs of spring bolts (one pair shown in fig. 4), which can act either as hinges or bolts, so that either end of the system can be tilted up, as shown by the dotted portions of fig. 3. Fig. 6 shows the holder with the case partly raised, fig. 7 the movement with the case removed, and fig. 8 the move ment raised for changing the spool. To fill the holder, the movement is raised as in fig. 8, the spool of negative paper inserted in its place under the brake or trailing roller, and fastened with the thumb screw on the side of the frame, the pawl g, fig. 2, on the tension barrel, is thrown off, the band on the spool broken, when sufficient paper is drawn out to reach over the bed or table to the reel; the movement is shut down, fastened to the back, and raised at the opposite or reel end; the to render them transparent, some were dipped into hot castor oil, as recommended by the Eastman Co. ; others were treated on the back with Mr. Ayres’ mixture of equal volumes of castor oil and ether, applied cold ; while a third series were treated with paraffin. When the hard paraffin or paraffin wax is used, it is necessary to melt it, but when paper is then drawn over the guide-roll and "slipped under the clamp on the red, and the reel turned*sulliciently to give the clamp a hold on the paper. Now, throw in the pawl on the tension drum, and put on the tension by turning the tension barrel over to the left until the paper is taut; shut down the movement and put on the case,