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[June 6,18611 Ju THE PHOTOGRAPHIC NEWS. 272 subject and treatment are far from artistic, and evidently un fitted for the panoramic lens ; others again, such as the general landscapes (deducting for faults of inexperience), have a breadth of effect and completeness totally unobtainable by aid of any other form of lens. I was well aware before com mencing operations of its unfitness for rendering pure architec ture ; but I wished to satisfy myself, by experiment, of the ex tent of error and distortion arising from the necessary curva- tion of the glass. On examining the specimens you will observe that, except in cases were a straight row of houses runs across the plate, the horizontal curvature is quite inappreciable by the eye, and I can vouch for it that for ordinary landscapes the effect is apparently perfectly natural. I now proceed to the principal object of this paper, viz., the practical details. My short experience of a few days will not warrant me in saying that my mode of procedure may not be considerably modified by future practice and improvement in the apparatus. On the latter point I have some suggestions to make, which will fall in their proper place at the close of this paper. It would have been more satisfactory to myself, and probably to you, could I have been able to lay before you a larger number of specimens; but it was impossible for me to get together more than eleven plates, on all of which I took pictures once, and some twice. Failures are awkward things to deal with in any way. I shall not detail mine ; but if the instructions and precautions about to be given seem in some respects too minute, you may be assured they are for the pur pose of avoiding failures experienced by myself. The Camera and Lens.—The camera having two spirit levels fixed at right angles on its upper surface—a plan, by-the-bye, I should like to seo introduced into all cameras—is readily adjusted to the level. The lens when unscrewed in the middle should be filled with distilled or boiled spring water. If ordi nary water be used the consequence will be that, in the course of an hour or so, the air contained in the water agglomerating into a multitude of little bubbles will adhere most obstinately to the inside surface of the lens, and cause irregular refraction and confusion in the image. Care also should be taken that the stop inside the lens—an ingenious contrivance called, I think, the “ butterfly stop,” from its not bearing the most dis tant resemblance to that insect—be adjusted with its longer axis quite horizontal: this is in the direction of the greater length of the plate. Cleaning the Plates.—The plates should be ground or roughed on the surface all round, to the distance of about 1 inch from the edge. This may readily and quickly be done by filing a rectangular notch in a piece of copper—an old penny piece will do very well—and rubbing along the edge with some rather coarse emery powder and water. The collodion will hold on to this rough part with great tenacity, and prevent, what is other wise most inevitable, the total destruction of the film during some part of the after process. The thorough cleaning of the surface, is a much more difficult operation than with plate-glass, arising probably from it being originally unpolished. Never theless, the fact is certain, and recourse must often be had to strong solution of soda, and afterwards nitric or sulphuric acid, to remove the last traces of dirt. In all cases, when the plate has once been varnished, strong acid will bo required to remove impurities from the rough edge of the glass. A padded cushion for the purpose of polishing is sold along with the apparatus; but I have found it more convenient to dispense with this, and in one hand, covered with chamois skin, to hold the plate and polish with the other. Coating the Plate.—The collodion should possess no glutinous or contractile properties, and still contain a large proportion of alcohol to allow the film to set slowly, and thus give more time for coveringly the plate evenly. The operation will scarcely be intelligible from a mere description. I hold the plate in the left hand balanced on the tips of the fingers and steadied by the thumb of the same hand resting with gentle pressure against the corner. Pour on that end a body of collodion suffi cient (but notin great excess) to cover the whole: then with a tremulous motion of the hand, which prevents streaks, and by gradually tilting the held end, direct the wave of collodion evenly and slowly till it reaches the other end. At the moment of its arrival there, pour off the excess from the corner into the bottle; but this must be done very quickly, and the plate turned back into its original vertical position, otherwise ridges will be formed diagonally across, and will be very conspicuous in the finished negative. Excite in the usual way. The time of exposure seems to me to be rather less than that nearly jaleff immer beuse srfaei which larger, larger rent t becomi larger hut th: gain, i tion fo Plat to the are shr the pla no left fect-l A varit image Bhich limited over t other r Mat Barket Allie hedif Frame, interpo there v the shi Cushior Coverec a simp Inc these i are off a lens my she wll,I photog 1, 4agno ? f iou itrule light, "hich "ant 0 . Sue by the agni Kema especi r <dne. Burpa Photo ctrios of 40( mnente graph Hans Piesol server Muni Naple M. — — required for Ross’s 44-inch single lens. The longest expo® under a rather dull leaden sky, was 20", and the shortest.® 1 ^ more favourable circumstances, 2" or less—in fact, as fasts could open and close the shutter. Still you will observe" latter cases very considerable detail in the dark green" ground, and the driving clouds in the distance show their “ line and shading very distinctly. The Development.—First, with pyrogallic acid.—Dilute AC grain-to-the-ounce-of-water solution of pyrogallic acid witll or five times its bulk of water, which pour over the plate M same manner as the collodion was applied. Tilt it backy3 and forwards till the picture has begun to develop evenlI over. A stronger solution, with a few drops of nitrate ofs solution added, may then be applied without danger of si and uneven development, until the requisite intensity has" obtained. Second development, with iron.—In some of my prelinla experiments I developed with pyrogallic acid, and would WI continued to do so from choice had not my collodion contD a pretty strong proportion of bromide, which I find contrl2 much to slowness and thinness of negative with that develf I had no alternative, then, but to use an iron salt; * under any circumstances, it is rather difficult to cover flat plate always evenly with that solution, the difticul"l much increased in the case of a curved surface. I have," fore, devised and constructed, very roughly as you see, aZ of rocking dish of gutta percha, the bottom having the % curve as the plates. Two ounces of about a fifteen-grain” solution poured into this was amply sufficient for one neg The plate, gently dropped in and quickly rolled about.) develop very evenly. The iron solution thus used need 108 thrown away, but with the addition of another ounce or82% serve over and over again without any seeming badetf The negative may now be washed gently; intensified t proper degree with pyrogallic acid and silver; fixed a usual way, by pouring on and off a saturated solution of and, finally, well washed. It was occasionally inconvenient for mo to intensify i diately after the iron development, on account of scard' water, and for other reasons. Under such circumstanWa fixed with hypo, after the application of the iron develv partly washed, and then stowed the plates away in the 003 future treatment at home when more at leisure. I 40a sure but this mode of re-development gives a more vi8 picture than the other, provided the iron developer has 3 long enough to bring out all the details ; it is, at alle more convenient for field-work. It requires groat some precautions, but may be safely done in the fol i ’ manner:— After drying and slightly warming the plate by tK apply with a camel’s-hair brush Soehnee or other varn I round the edge to the depth of one-eighth inch or thero taking care to fasten in the same way the edges of all ind cracks or rents in the film. This prevents water, 80’ finding its way underneath the collodion, and renden strong and adhesive that the plate may now be washed • danger and intensified to any extent with pyrogallic ac" silver. A I Having thus detailed, I hope clearly enough to be,! stood, the manipulations I have found to bo theb24 insuring good negatives, I would now suggest some ina ments in the apparatus which will make this object moro . attainable. E With respect to the lens and camera nothing betten for their purpose could possibly be devised. They are Pa The former, being only rather over five inches focus.v exquisite definition to the very edge of a rectang"ag 9,44} inches, comprehending an angle of about 10546600 and the camera is in every way well fitted for giving effedv, enormous angle. In one of the specimens on the “ Pulteney Bridge ”—I had the curiosity to measure ti « included after trimming the print for mounting, ,p‘ rather over 97° and is of course pretty nearly the sat other cases. Ji K On the other hand the material of the bath—gutta" is apt to contaminate the nitrate of silver (especially Ij) weather) with organic matter. I do not see any foed 0 difficulty in constructing receptacles of glass covents X externally with gutta-percha ; or, indeed, what prey 6 ” " I from being cast in sold glass ? I object also to its shage sides, as you may observe, are arcs of two concentric
