US75493A - vogel - Google Patents

Description

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nveyzfar- /nesses- KM 45,0 w wg; j y '7 ll l r omas ravens co, muvo-umwwumafou n c DR. H. voert., or Banus, PRUss'iA, Assieme-'ro wnsoN AND' noon f or PHILADELPHM, PENNSYLVANIA.

Letters .Patent No. 75,493, dated llarch i0, 1868.

vIlllllltOVFlVlEN'I IN PHOTOMETERS.

ro ALLvwHoM rr MAY- eoNcERN;

Be it known that I, Dr. H. VOGEL, of Berlin", Prussia, have invented a new and improved Photometer; and- I do hereby declare that the-following is a full,.clcar, 'and exact description thereof, which will enable others skilled Jin the 'art-to make and use .the same, reference being had tothe accompanying drawings, forming part of this specification, in 'which-Q- Figure l represents a perspective viewof'my improved photcmeter. Figure 2 is longitudinal vertical sectio'n of the same. Figure' is a vertical transverse section of the same. Similar letters of reference indicate corresponding parts.

The object of this invention is to determine, with exaetness, -the time required for copying photographic. negatives. v i i i By the copyingprocess, positives are to be produced upon papier from a negative taken in the camera.v

For this' purpose a piece of very sensitive paper is placed upon the negative, and into the lightnin which" it remains until it has received the required impression fromv the negative. This impression is ei-thervdirectly visible or. is made visible by a separate process. If it is directly visible, it is easy to determine the lengtlrof time during which the paper and negative are to bc ezgposcd'to the light, as the progressief the copying process canbe easily noticed. But if the .process 'is invisible, it is imperatively necessary to determine beforehand the required length of time. If the right time has not been. chosen, itis impossible to correct the mistake. -But it is very difficult to determine the time, owing to the variations of the chemical ,intensity of daylight.' 'lfo overcome"thesediiculties is the object of my invention', by means .of which the necessary length of time for 'exposing any desired pieture in any desired weather to the light can at once be ascertained.

in the drawing, represents a box, made of wood or other suitable material, of suitp'ble size and shape, and providedwith a hinged lid, B, as shown. I The lid B consists of a wooden o r other frame, a, by which a ',iglass'plate, b, is held. On the under-side of this glass plate is secured a series'of'thin strips of paper, C, which are arranged in layers, each lower layer projecting beyond the edge of the layer aboveas is clearly shown in iig. 2, 'The, step system thuisl produced representen semi-transparent medium, the transparency of. -which decreases by degrees toward the thicker end. Black .figures upon the under side of the lower longest Vstrip of paper indicatethe' number of layers arranged above each such `gure, as will be clearly understood from figs. 1 and 2. AThe whole cover B, with the paper system on it. can be'folded down and fastened, by meansv offa small hook, c,-,or "other equivalent device. l

Within the box A is arranged a sliding false bottom, D, which is, by means of a springl or springs, E, pressed upward against the paper, C, as shown'ing. 2. Upon this false bottom are placed a number of sensitive-paper strips. -For this purpose I do not use silvered paper, which can only be preserved a short time, but paper' which has b'een saturated with alkaline ehromate, and which, as I have found, canvbe preserved'for four weeks; These paper strips are presscdrmly against the under side'oi` the paper, C, so as to fit well to the same. If this apparatus is then exposed to the light, the separate sections of the upper sensitive paper will be successively darkenedfrst that portion under No. 1, then that under No. 2, ofthe paper, C, and so forth. The paper will gradually become darker 'towards the thicker portion of the paper, C; the quicker, the more sensitive the paper is. Now it will be easy to recognize how far the chemical effect of the light has operated, :is the printed portions of the paper, C, do not let the light passvthro'cgh the paper, and will consequently leave that portion of the lower sensitive paper which is under thergure light, and these {ign'res vwill therefore remain light on the sensitive paper after the* same has been aiected by the light. If the box is then opened in a not very light room, the place, to which the light'has been able to atleet the chromo-paper will lbe easily ascertained, and the last ligure thus -produced oli-the paper will showhow many thicknesses of the paper, C, the light hasbeenable to pass through, during a given space of time, whichoccupies but a few seconds'.

With this device will be easy to indicate the correct timefor exposing a negative to the light, especially when thelnovel carbonprint'is employed; The instrument isexposed to the light atvthe same time as thenegativ'e whichis tobe copied, and if the instrument shows six degrees, the irst'quartr o f the negative is the required intensity. The 'same' is the correct degree for copying. j

covered; if eight, the-second; if ten, the third; and if twelve, the fourth. In vthis manner the sinjgle parts to 6, 8, 10,v and 12, have been copied. The picture is then developed, and notice is .taken which part .of it shows If a number of negatives are to beprinted, they are arranged according to their intensitygivhich is easily done by experts, and are then divided into three classes, so that they can be easilymanaged. I y

vThis apparatus ean also he used with good advantage for indicating the time of taking negatives in lthe camera from bodies. v

Having described my invention, what I claim as new, and desire to sechre by Letters Patent, is

1. The arrangement of the transparent paper strips C, which ar'e arranged in steps, and which -axe divided into sections, each section having an opaqte portion, substantially as herein shown and described.

2. The box A,when provided with a cover, B, 4having a glass' plate, b, and the step-formed paper C, and

with the sliding false bottom D pressed against `the paper C, by means of a spring, E, as set forth, :illv niade and operating substantially as herein shown and described.

3. 'lhe paper strips, saturated with alkaline'chromate, when they are applied lo a photometer, snbstantially as herein shown and described.

n The above speciiieatonuof my invention signed by me, thisv twentieth day :of November, 1867. l DB. 11.--VOGEL.

Witnesses:

v13. BnEKMNN, J. C. 'ScHAAnwcnrnm

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