The photographic news

• Bandzählung: 35.1891
• Erscheinungsdatum: 1891
• Sprache: Englisch
• Signatur: F 135
• Vorlage: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: SLUB Dresden
• Rechtehinweis: Public Domain Mark 1.0
• URN: urn:nbn:de:bsz:14-db-id1780948042-189100009
• PURL: http://digital.slub-dresden.de/id1780948042-18910000
• OAI: oai:de:slub-dresden:db:id-1780948042-18910000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

522 THE PHOTOGRAPHIC NEWS. [July 24, 1891. that as the plunger works slowly down the red-hot mass, it is surrounded by smoky flames. It presently forces the cylinder into the well, and when the end of the stroke is reached, a stop piece is inserted through an opening in the upper part of the well, so as to arrest the edge of the cylinder while the reverse action of drawing out the plunger is proceeded with. Directly the finger is drawn out of the glove—in other words, immediately the plunger is raised out of the cylinder—the latter drops down below with a heavy thud, still in a red-hot condition. This operation of hot drawing is repeated again and again in rams of diminishing size until the cylinder assumes the diameter and length required. This hot drawing leaves the surface of the metal marked with longitudinal lines, not unlike the glacier scratches on a rock, albeit they are straighter and more regular. But the next operation not only obliterates these markings, and gives the metal a smooth surface like that of polished silver, but it also confers upon the material a homogeniety which it did not before possess, and with out which it would never bear the pressure which it is destined to withstand when finished. This operation consists in a final application of the hydraulic ram while the metal remains perfectly cold, instead of red- hot as in the previous eases. As a result of these various hydraulic operations, we have a perfectly formed cylinder closed at one end, and we now follow it into another department of the works, when its open end is once more brought in a furnace to a red heat. The object of this is to make the metal soft while the shoulder and neck of the vessel are formed. To accomplish this, the heated open end of the cylinder is laid horizontally upon a kind of semi-circular cradle, and is held there by tongs handled by two men. Another workman places over the open end a die of the form shown in fig. 4, and while the cylinder is slowly turned round in its cradle, two sledge hammers are brought down with frequent blows upon the die, closing in the end of the cylinder, but leaving a central hole as shown in fig. 5. Further operations reduce the opening still more until it is closed altogether, and a projec tion is formed as shown at fig. 6. This projection is now bored through, and the cylinder is ready for testing. The cylinder is submitted to a water test, the liquid being forced in until the gauge shows a pressure of two tons to the square inch. Cylinders have been known to give way under this ordeal, but without any dangerous consequences. The metal simply rips up, making a report at the moment of fracture as loud as a gun. The wonderful strength of the metal employed may be gauged by the circumstance that the walls of the cylinder designed to hold 100 feet of gas are only 1% of an inch in thickness. During the manufacture of the cylinder, as we have already indicated, much oil is used, and, so far as steel can be saturated with that fluid—in the popular sense —the metal is in that state. It is essential that this oil should be completely got rid of, and this is carefully done before the cylinder is charged with gas. Previous to such charging, the vessel has to be fitted with its valve. Of these valves there are three kinds, known respectively as the Brin, the Birmingham, and the Manchester. Each has its admirers, but we cannot here discuss their individual merits. The charging of the cylinder is brought about by a powerful pump having three cylinders so arranged that the compressed contents of the first cylinder are still further compressed in the second, and still more highly in the third. The filling of a 100-ft. cylinder occupies about half-an-hour. THE “OPTIMUS” WORKS. Br the above title the workshops of Messrs. Perken, Son, and Rayment may fairly be called, for “Optimus” is their well-known trade-mark, and it is evident to the most casual visitor that they make every possible effort to turn out “the best ” work. Such a visit did we pay to this enterprising firm a week back, and we saw much that was interesting, and work which involves the patient fashioning from the raw materials of such delicate instru ments as cameras, lenses, optical lanterns, and all the multifarious things which are constructed for the aid of the modern photographer, cannot fail to be of interest to the spectator. The premises occupied by this firm are very extensive, and comprise a series of workshops fitted with every appli ance for cabinet making, at Saffron Hill, and the main building at Hatton Garden, where the lenses are ground, and where various other operations are carried on with a large staff of workmen. Visiting first of all the cabinet works at Saffron Hill, we are shown, stored in the lower part of the premises, a large stock of —rood, which, how ever, represents only that required for present needs. On the second floor are cutters, vertical and horizontal, circular saws, and planing machines. It is here that the various parts of the cameras and wooden bodies of the lanterns are cut out—one can hardly say in the rough, for everything is done to guage, and the fine grooves, the rebates, and other shapes are cut to the greatest nicety, and far more accurately than they could be done by hand tools. The making of a camera is no longer, as it was twenty years ago, such a simple affair that any carpenter can turn one out. In those days, one box sliding within another with something like accuracy, and a screw to hold them together, was all that was either looked for or required. Rising fronts, swing-backs, leather bellows, rack-work, and all the other niceties of the present machine were undreamt of. But now that the camera has grown from this primitive form into what may be described as a deli cately adjusted philosophical instrument, a different race of workers has become necessary for its manufacture. With the old workmen have been discarded many of the | old tools, and, indeed, it would be difficult, if not impos-