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better known as Sibt al-Maridini, includes an introduction, 20 sections, and a conclusion. The treatise discusses a range of issues in astronomy, surveying, and mathematics. It describes the sine quadrant and parallel circles, and explains how to measure the width of a river, the angle of a star, the depth of a well, or the height of a mountain.
A quadrant is an instrument used to measure angles up to 90°. Different versions of this instrument could be used to calculate various readings, such as longitude , latitude , and time of day . Its earliest recorded usage was in ancient India in Rigvedic times by Rishi Atri to observe a solar eclipse.
The size of a book is generally measured by the height against the width of a leaf, or sometimes the height and width of its cover. [2] A series of terms is commonly used by libraries and publishers for the general sizes of modern books, ranging from folio (the largest), to quarto (smaller) and octavo (still smaller).
The actual, physical height of any given portion of the font depends on the user-defined DPI setting, current element font-size, and the particular font being used. To make style rules that depend only on the default font size, another unit was developed: the rem. The rem «rem unit», or root-em, is the font size of the root element of the ...
The frame of a sextant is in the shape of a sector which is approximately 1 ⁄ 6 of a circle (60°), [2] hence its name (sextāns, sextantis is the Latin word for "one sixth"). "). Both smaller and larger instruments are (or were) in use: the octant, quintant (or pentant) and the (doubly reflecting) quadrant [3] span sectors of approximately 1 ⁄ 8 of a circle (45°), 1 ⁄ 5 of a circle (72 ...
The book-cutting machine works with three knives and uses the knife-cut principle. The knife-cut principle operates with only one knife per edge which cuts against a rubber surface. This surface supports the cut force. The three-knife-trim is performed in one step. The block is aligned and fixed by the pressure bar.
The point was first established by the Milanese typographer, Francesco Torniella da Novara (c. 1490 – 1589) in his 1517 alphabet, L'Alfabeto.The construction of the alphabet is the first based on logical measurement called "Punto," which corresponds to the ninth part of the height of the letters or the thickness of the principal stroke.
The mural quadrant at the Royal Observatory, Greenwich, in east London. Ptolemy's mural quadrant at Alexandria. This instrument is also referred to as a plinth. [6] The obsolete constellation Quadrans Muralis represents a mural quadrant. The mural quadrant at the Mannheim Observatory in Germany. [7] This is another of John Bird's instruments.