Suche löschen...
The photographic news
- Bandzählung
- 24.1880
- Erscheinungsdatum
- 1880
- Sprache
- Englisch
- Signatur
- F 135
- Vorlage
- Hochschule für Grafik und Buchkunst Leipzig
- Digitalisat
- Hochschule für Grafik und Buchkunst Leipzig
- Digitalisat
- SLUB Dresden
- Lizenz-/Rechtehinweis
- Public Domain Mark 1.0
- URN
- urn:nbn:de:bsz:14-db-id1780948042-188000001
- PURL
- http://digital.slub-dresden.de/id1780948042-18800000
- OAI-Identifier
- oai:de:slub-dresden:db:id-1780948042-18800000
- Sammlungen
- Fotografie
- LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
- Bemerkung
- Exemplar unvollständig: Seite 1-82 in der Vorlage nicht vorhanden
- Strukturtyp
- Band
- Parlamentsperiode
- -
- Wahlperiode
- -
- Bandzählung
- No. 1143, July 30, 1880
- Digitalisat
- SLUB Dresden
- Strukturtyp
- Ausgabe
- Parlamentsperiode
- -
- Wahlperiode
- -
-
Zeitschrift
The photographic news
-
Band
Band 24.1880
-
- Ausgabe Ausgabe I
- Ausgabe Ausgabe I
- Ausgabe Ausgabe I
- Ausgabe Ausgabe I
- Ausgabe Ausgabe I
- Ausgabe Ausgabe I
- Ausgabe Ausgabe 83
- Ausgabe Ausgabe 85
- Ausgabe Ausgabe 97
- Ausgabe Ausgabe 109
- Ausgabe Ausgabe 121
- Ausgabe Ausgabe 133
- Ausgabe Ausgabe 145
- Ausgabe Ausgabe 157
- Ausgabe Ausgabe 169
- Ausgabe Ausgabe 181
- Ausgabe Ausgabe 193
- Ausgabe Ausgabe 205
- Ausgabe Ausgabe 217
- Ausgabe Ausgabe 229
- Ausgabe Ausgabe 241
- Ausgabe Ausgabe 253
- Ausgabe Ausgabe 265
- Ausgabe Ausgabe 277
- Ausgabe Ausgabe 289
- Ausgabe Ausgabe 301
- Ausgabe Ausgabe 313
- Ausgabe Ausgabe 325
- Ausgabe Ausgabe 337
- Ausgabe Ausgabe 349
- Ausgabe Ausgabe 361
- Ausgabe Ausgabe 373
- Ausgabe Ausgabe 385
- Ausgabe Ausgabe 397
- Ausgabe Ausgabe 409
- Ausgabe Ausgabe 421
- Ausgabe Ausgabe 433
- Ausgabe Ausgabe 445
- Ausgabe Ausgabe 457
- Ausgabe Ausgabe 469
- Ausgabe Ausgabe 481
- Ausgabe Ausgabe 493
- Ausgabe Ausgabe 505
- Ausgabe Ausgabe 517
- Ausgabe Ausgabe 529
- Ausgabe Ausgabe 541
- Ausgabe Ausgabe 553
- Ausgabe Ausgabe 565
- Ausgabe Ausgabe 577
- Ausgabe Ausgabe 589
- Ausgabe Ausgabe 601
- Ausgabe Ausgabe 613
- Ausgabe Ausgabe 625
- Register Index 631
-
Band
Band 24.1880
-
- Titel
- The photographic news
- Autor
- Links
- Downloads
- Einzelseite als Bild herunterladen (JPG)
-
Volltext Seite (XML)
THE PHOTOGRAPHIC NEWS. JULY 30, 1880.] 363 the true meridian (which angle is technically called declin ation, or, popularly, variation of the compass), and inclined at an angle with the horizon of about 674° (technically called the dip), and would be subject to diurnal changes, both right and left and up and down, as well as permanent changes of position from year to year. The value of the declination in the year 1840 was about 23 3°, and that of the dip was 69°. In practice, the declination magnet is suspended so as to be horizontal, and the changes right and left will be the same as in the inclined position ; and the investigation of the diurnal changes of the dip are found by the use of two magnets, one called the horizontal force magnet, and the other the vertical force magnet. By combining the results found by the use of these magnets the variations of the dip are known. A horizontal revolving cylinder will register the con tinuous records of both declination and of horizontal force. The continuous record of vertical force necessitates the use of a vertical revolving cylinder. Atmospheric Pressure. The continuous record of atmospheric pressure is obtained by means of a syphon barometer; on the mer cury, in the lower leg, is placed a glass float, partly im mersed in the mercury; to the float is attached a vertical rod, supported by a horizontal bar which carries a vertical plate of mica having a small horizontal slit; through this slit the light of a lamp falls on a cylindrical lens, and from thence to the photographic paper. The scale of the barometer is about four inches on the paper to a change of one-inch in the reading of the baro meter, and these changes, being vertical, can be registered on the same cylinder as that devoted to the vertical force. .Spontaneous Earth Currents. It is well known that spontaneous galvanic currents are almost always passing in the earth, and are at times very powerful, and frequently troublesome in telegraph offices. These earth currents are registered at Greenwich by means of photography. There are two wires crossing each other near the Observatory; these wires, from an earth connec tion at the Royal Observatory, extend in two directions nearly at right angles to each other to considerable dis tances from the Observatory, where they again make earth connection. Two magnetic needles, one for each wire, each suspended by a hair, so as to vibrate horizontally within a galvanometer, are placed respectively in the courses of the two wires. A current of one kind, in either wire, causes the corresponding needle to turn itself in one direction ; a current of the opposite kind, in the other direction. To the carrier of each magnet is fixed a small plane mirror, which receives all the motions of the maguet. The. light of a gas lamp passes through a small aperture, and shines upon the mirror. A spot of light is thus formed upon the photographic paper wrapped upon the cylinder. Dry and Wet Bulb Thermometers for Temperature of the Air and Evaporation. These of necessity must be out of doors, and their bulbs open to all changes of temperature and humidity. The bulb of the thermometer employed as wet bulb is kept moist by the capillary passage of water along cotton lamp wicks leading from a vessel of water. The bulbs are eight inches in length, and their centres about four feet above the ground. A vertical revolving cylinder and the carrying time piece are mounted on a stand measuring thirty inches by twelve, suppotted by four legs; the stems of the dry and wet bulb thermometers pass up through the table and between the lenses and the adjacent surfaces of the cylinder ; the long cylindrical bulbs are sufficiently below the stand to be freely influenced by the currents of air, and, at the same time, to remain wholly unaffected by the heat of the lamps, which are placed on wooden supports at each end of the stand, at such a height that the flame may be opposite the middle of the photographic paper on the cylinder. As it is impossible to superpose two registers of these instruments on the same paper, which may be done with out inconvenience when the jndication consists of a dark line only, as in the photographs of the barometer and the magnetometers, the time-piece is so constructed that the hour hand makes half a revolution in twenty-five hours. By this arrangement the two halves of the paper surrounding the cylinder give respectively a perfect record of the two instruments. The glass cylinder is covered by a concentric cylindrical zinc case, having slits on opposite sides corresponding to the stems of the instru ments, which are capable of being closed by sliding doors ; by these means the cylinder, protected by its case, may be carried to or from the room in which the photographic manipulations are conducted without any risk of exposure to light. The whole apparatus is also covered by a wind and water-tight zinc case which rests on the stand, and is divided into separate compartments for the lamps by a partition towards each end for the purpose of more com pletely isolating the thermometers from the heat produced by their combustion. The cylindrical arrangement above described, so obviously desirable in enabling the two thermometric instruments to be registered by one apparatus and on one piece of paper, was at first open to a grave objection, which has, however, subsequently been entirely removed. This has been effected by placing fine wires opposite to each degree across the aperture in the scale frame, through which the light is transmitted to the stem of the instru ment. By these wires a minute portion of the exposed paper is protected from light, and thus the darkened portion of the register is traversed by a series of parallel lines corres ponding with the scale of the thermometer. In order to remove any ambiguity in the reading of this scale, a coarser wire is placed at every ten degrees, and an additional coarse wire at the points 22°, 54°, 76", and 98°; as one of these points may always be made to appear on the register, the relative position of the extra coarse wire will determine the points of the scale which it represents. It is very evident that the apparatus must afford some ready method of marking the time-scale on the paper—that is, of identifying any given epoch of time with the indi cations of the register. This is effected by closing at any two known times the sliding doors of the cylindrical case for five minutes, and then re-opening them. Two undarkened lines will be observed on the paper, corres ponding to the known time. The scales of the thermometers in use have about 80° to one inch, from the registers of which the temperature may be easily read. Of this scale, a space of about 608 may be illuminated at one time, and in order that the temperature indicated may always be within the field, the thermometers are capable of being raised or lowered by a screw, so as to bring the mean temperature of the season nearly opposite the middle of the paper ; thus there is no probability that the record of any unusual and extreme changes of temperature will be lost. Uniform rotatory motion is given to the cylinders by the action of clock-work ; for two of the cylinders, which revolve in twenty-four hours, and for the thermometer cylinder, which revolves in fifty hours, the axis is placed opposite to the centre of the chronometer, and a fork at the end of the hour-hand takes hold of a winch fixed to the plate of the cylinder. For the horizontal cylinders the plane of the chronometer work is vertical, for the vertical cylinders it is horizontal. The cylinders employed for the declination and horizontal force registers, for the vertical force and barometer registers, and for the earth current registers, are 11} inches high, and 144 inches in cir- I cumference; those for the thermometers are 10 inches ' high, and 19 inches in circumference.
- Aktuelle Seite (TXT)
- METS Datei (XML)
- IIIF Manifest (JSON)