used in photography, consists of a lighttight box having at one end an achromatic lens and at the other a ground-glass plate and a space in which a plateholder containing a sensitized plate can be placed. In order to regulate the amount of light passing through the lens and to increase the distinctness by cutting off the outside rays, the lens is provided with a series of diaphragms with different-sized openings. The camera is so constructed that the distance between its ends can be varied. By making this the proper distance the image is brought to a focus on the ground glass, then the sensitized plate is put in its place, and the exposure is made.

The plate is afterward developed by means of certain chemicals. This process reduces the silver salts in the film to a metallic condition, forming a dark layer wherever the light has acted. The salt that has not been acted upon by the light is dissolved out by putting the plate in a solution of hyposulphite of sodium, after which the plate is washed and dried. The plate is now a negative (Fig. 1), and prints can be made from it upon sensitized paper (Fig. 2)

Figure 3 shows a moving picture camera; Fig. 4, a machine for sending a photograph a long distance by wire.

IG. 539.-The Telestereograph Transmitter

 By this instrument, and a receiving apparatus, photographs can be sent by wire hundreds of miles in a few minutes, and are distinctly reproduced. The transmitting record is a photograph prepared in bas-relief on a revolving cylinder. A stylus connected to a telephone transmitter traces the record, the current varying with the height of the record. This variation in current is transformed at the receiving end into various gradations of a beam of light on a sensitized cylindrical plate, revolving like the first, and from this the picture is developed by the ordinary process. The picture at the left was received in New York from St. Louis by this apparatus in November was re 1920

اخر الاخبار

اخبار العتبة العباسية المقدسة

قسم التطوير يقيم دورة عن أخلاقيات المهنة للمنتسبين الجدد

تتضمن زيارة المراقد المقدسة في كربلاء.. معهد القرآن الكريم النسوي ينظم سفرة دينية لطالباته

المجمع العلمي يحتفي بذكرى ولادة الإمامين الباقر والهادي (عليهما السلام)

قسم الشؤون الفكرية يطلق فعاليات الأسبوع الثالث من برنامج البذرة الصالحة

المزيد

الآخبار الصحية

ثورة طبية.. الذكاء الاصطناعي يكشف سرطان الكلى في وقت قياسي

لتعزيز الطاقة والتغلب على التعب.. عليك بـ7 طرق بسيطة

لتحسين الهضم والتحكم في الشهية.. ما أفضل وقت لتناول التمر؟

خبراء يكشفون تأثير الاستحمام في الظلام على جودة النوم !

المزيد

الآخبار التكنلوجية

إزالة ثاني أكسيد الكربون من الغلاف الجوي.. ما دور المحيطات والبحار؟

نظائر الهيليوم مقياس لاكتشاف رواسب الذهب.. كيف ذلك؟

الصين تطلق أول ناقلة نفط خام ذكية في العالم تعمل بالميثانول

الزمن على المريخ أسرع من الأرض.. دراسة علمية تكشف الفوارق

المزيد

مواضيع ذات صلة

The Terrestrial Telescope

The Polariscope

The Simple Microscope

The Compound Microscope

The Astronomical Telescope

Galileos Telescope the Opera Glass

The Prism Binocular

The Eye as an Optical Instrument

The Blind Spot

The Adaptability of the Retina

The Invisible Spectrum

Fraunhofer Lines