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Group II. - Class 4 - Expo Paris 1867

Group II. - Class 4 at the Exhibition Expo Paris 1867


The manufacturers of cameras are tending more and more to achieve two kinds of improvements, which consist on the one hand in reducing the material of travel cameras, and on the other hand in eliminating the hand of man wherever the automatic straightness of mechanics aided by electricity can be substituted for his skill.

In the midst of the various products in the showcases of Mr. Geymet and Mr. Alker, we noticed two innovations that are as important as they are ingenious. The first is a binocular which appears to be absolutely similar to those used in theatres.

Only if, with the binocular of which Mr. Octave Nicour is the inventor, and of which Mr. Gevmet and Mr. Alker are the only manufacturers, one looks at a landscape, one can see the whole of the city,
one looks at a landscape, one will see on one side the upside down landscape, as it is usually painted on the frosted plate of an ordinary lens, while on the other side, where the eye cannot penetrate, this same landscape will be fixed on a small photographic plate that has been previously introduced. With this small device, which does not weigh more than a kilogram and a quarter, including the accessories, one can look for any point of view with the eye and instantly, with a movement of the little finger, allow the light to perform the mysterious operation of reproduction: it is in a way the shorthand of the gaze.

For those whose hand is not sure enough, the manufacturers have established a light and convenient cane stand, on which the photographic binocular can be placed. Our engraving shows it in this position.

The photographic binoculars were built for the use of dry collodion.

However, ordinary collodion can be used, but the accessories required for wet collodion are contrary to the intention of the inventor, who wanted to create an essentially portable apparatus.

In our engraving we see, in addition to the binocular mounted on its stand, the drawing of the binocular itself in a larger proportion, and a graduated washer whose use we will indicate.

This washer is hollow; it has only one opening on the side wall which forms its thickness, and which is hermetically closed by a copper blade sliding with gentle friction between two grooves. In the interior of the disc there are fifty other grooves in which are placed as many mirrors / prepared with dry collodion. On the side of the binocular intended for photographic reproduction, there is an opening absolutely similar to the one we have just described when talking about the disc. The only difference is that the copper blade opens in the opposite direction, still with a gentle rubbing action.

The glass contained in the washer is brought to the opening by means of a regulating knob. In this state, one only has to slide the two copper blades of the binocular and the washer, making their openings coincide and pushing the apparatus towards the big end of the telescope. The two openings open at the same time, and the prepared glass slides quite naturally into the space provided for it opposite the objective contained in the binocular, and without suffering any premature alteration of light.

The shutter is then opened, and once the exposure has been made, all that is required to remove the printed glass is the reverse of the operation we have described, in order to introduce the glass before exposure to the light. The printed plates are then treated with the ordinary photographic developers in a laboratory equipped with yellow glasses.

Chemistry has now provided us with dry collodions that are not only fast, but also retain their sensitivity for nearly a month. The views obtained by the photographic binoculars are small enough for amateurs to keep a souvenir of their trip, and very good for enlarging.

I do not want to end the analysis of this interesting invention without saying a word about another invention which is entirely the work of the skilful builders of the
I do not want to end the analysis of this interesting invention without saying a word about another invention which is entirely the work of the skilful builders of the photographic binoculars: Messrs Geymet and Alker.

Electricity has been called upon to play a part here, in order to save the time of the man who is obliged to wait by the lens until the operation of the light is completed.

Everyone knows that the exposure time varies according to the intensity of the light, and that the operator's intelligence alone is capable of assessing it. Nevertheless, Mr. Geymet and Mr. Alker used electricity to regulate the exposure time and closed the shutter at the right moment when the action of the light was complete.
A loose needle, which is placed in a direction corresponding to the exposure time required by the intensity of the light, once placed in the position it must occupy during a certain period of the day, is simply turned, and at the same moment the lens is uncovered, a pendulum is set in motion, the print is made, the lens is closed, and finally a bell is set in motion, warning the operator that the po?e is finished.

This apparatus is made for exact experiments on the sensitivity of photographic products and various mixtures. It is also very advantageous - and this is a very important point - for reproductions which often require a long exposure time, as well as for meteorological observations for which the exposure is still long.

The showcases of Mr. Geymet and Mr. Alker also contain a host of interesting innovations which we cannot dwell on.

I will conclude by drawing the attention of visitors to some charming prints on gold, silver or bronze paper, or coated with brilliant colours, which admirably imitate, depending on the tones used, the old silver or gold illuminations so admired in the missals and books of the Middle Ages.

©L'Exposition Universelle de 1867 Illustrée