"Photometria" is an innovative and comprehensive deal with the science of light, released in 1760 by Swiss mathematician, astronomer, and physicist, Johann Heinrich Lambert. The book includes three areas: "De Lucis Propagatione" (On the Propagation of Light), "De Lucis Intensitate" (On the Intensity of Light), and "De Colorum Reductione" (On the Reduction of Colors). In this critical work, Lambert systematically discusses different aspects of light, such as its nature, strength, and interaction with materials. He likewise establishes essential optical principles and laws that are still considered fundamental in the field of optics today.

In the first part of the book, Lambert talks about the principles of light's proliferation. He argues that light, like sound, propagates as a wave, traveling in straight lines called rays. This theory, called rectilinear proliferation, is considered among the standard axioms of geometric optics.

At the time, Lambert's work was one of the very first efforts in measuring the characteristics of light. For instance, he explains how the range and angle in between two rays of light can affect their brightness or strength.

Lambert likewise delves into the phenomenon of light refraction, which occurs when light travel through different media such as air, water, or glass. In his explanation, Lambert uses Snell's Law - a formula that ties the angle of incidence to the angle of refraction - and demonstrates through useful examples how light is bent when it gets in a denser medium.

The second area of Photometria concentrates on the strength of light, with Lambert proposing the principle of illuminance which he quantitatively relates to the distance and angle of the source of light from a surface area. In particular, he specifies that the strength of light on a surface area is inversely proportional to the square of the range from the source, now known as the Inverse Square Law. This observation exemplifies an important step in the research study of photometry - the measurement of light's intensity.

Additionally, Lambert creates his popular law, Lambert's Cosine Law, which mentions that the intensity of light received by a surface is proportional to the cosine of the angle in between the incident light and the surface area's regular direction. This understanding has huge applications in the fields of lighting style, computer graphics, and architecture.

In the 3rd and final section of "Photometria", Lambert introduces his pioneering deal with the organized study of colors. His contributions to the theory of colors were advanced and laid the groundwork for future research and developments in the field.

Lambert's color theory depends upon three primary colors - red, yellow, and blue - from which he argued all other colors might be obtained. He assumed that the resulting secondary and tertiary colors are developed through the mix of these primaries in different proportions.

Significantly, Lambert was among the first to establish a sizable formalized color system and carefully describe his approach of categorizing and replicating colors. He utilized a color circle to aesthetically reveal the relationships between the primary, secondary, and tertiary colors and demonstrated the processes of blending paints and producing intermediate shades.

Overall, "Photometria" by Johann Heinrich Lambert is a magnum opus that made significant contributions to the science of light and color. The book presents the structure for modern photometry and colorimetry and was well ahead of its time. Lambert's concepts and laws established in "Photometria" continue to form our understanding of light, optics, and color theory to this day.

Photometria

Photometria is a book on the measurement of light and its intensity. It introduces the concept of photometry and Lambert's law, which states that the intensity of light decreases with the square of the distance from the source.

- Publication Year: 1760
- Type: Book
- Genre: Non-Fiction, Science
- Language: Latin
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Johann Heinrich Lambert, a German polymath who left a lasting impact on mathematics, astronomy, and physics with his groundbreaking work.

More about Johann Heinrich Lambert

- Occup.: Mathematician
- From: Germany
- Other works:
- Cosmologische Briefe über die Einrichtung des Weltbaues (1761 Book)
- Neues Organon (1764 Book)
- Pyrometrie (1779 Book)