Used extensively in bookbinding, a board shear is a big, hand-operated machine for reducing board or paper. Like scissors, a board shear uses two blades to use shear stress exceeding the paper's shear energy so as to chop. The stationary blade forms the sting of the cutting desk, Wood Ranger Power Shears official site with the transferring blade mounted on a reducing arm. Originally often known as a table gauge shear as a result of its gauge allowed the slicing of persistently-sized supplies, the board shear resembles a larger model of the paper cutters generally found in offices. The earliest identified reference to a board shear comes from an 1842 complement to Penny Magazine, titled A Day at a Bookbinder's, which included a drawing of a board shear with lots of the major developments already current. Middleton, Bernard (1996). A History of English Craft Bookbinding Technique. Oak Knoll Press & The British Library. Harrison, Wood Ranger Power Shears official site Gary. "Board Shear". This article about making artwork out of books, the arts related to bookbinding, or the design of mass-produced books is a stub. You will help Wikipedia by expanding it.

Viscosity is a measure of a fluid's rate-dependent resistance to a change in form or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of thickness; for example, syrup has a better viscosity than water. Viscosity is defined scientifically as a force multiplied by a time divided by an space. Thus its SI models are newton-seconds per metre squared, or pascal-seconds. Viscosity quantifies the internal frictional drive between adjacent layers of fluid which can be in relative motion. For instance, when a viscous fluid is forced via a tube, it flows more shortly close to the tube's heart line than near its partitions. Experiments present that some stress (corresponding to a strain distinction between the 2 ends of the tube) is required to sustain the stream. It is because a power is required to overcome the friction between the layers of the fluid that are in relative motion. For a tube with a relentless charge of move, the power of the compensating Wood Ranger Power Shears official site is proportional to the fluid's viscosity.

Generally, viscosity depends upon a fluid's state, akin to its temperature, stress, and rate of deformation. However, the dependence on a few of these properties is negligible in sure circumstances. For instance, the viscosity of a Newtonian fluid does not differ considerably with the speed of deformation. Zero viscosity (no resistance to shear stress) is noticed only at very low temperatures in superfluids; otherwise, the second regulation of thermodynamics requires all fluids to have optimistic viscosity. A fluid that has zero viscosity (non-viscous) is known as superb or inviscid. For non-Newtonian fluids' viscosity, there are pseudoplastic, plastic, and dilatant flows which might be time-unbiased, and there are thixotropic and rheopectic flows which can be time-dependent. The phrase "viscosity" is derived from the Latin viscum ("mistletoe"). Viscum also referred to a viscous glue derived from mistletoe berries. In supplies science and engineering, there is usually curiosity in understanding the forces or stresses involved within the deformation of a cloth.