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A Kelvin bridge, also called a Kelvin double bridge and in some countries a Thomson bridge, is a measuring instrument used to measure unknown electrical resistors below 1 ohm. It is specifically designed to measure resistors that are constructed as four terminal resistors.
John "Iron-Mad" Wilkinson (1728 – 14 July 1808) was an English industrialist who pioneered the manufacture of cast iron and the use of cast-iron goods during the Industrial Revolution. He was the inventor of a precision boring machine that could bore cast iron cylinders, such as cannon barrels [ 1 ] and piston cylinders used in the steam ...
This did not allow for precision, especially in cutting iron, so screw threads were usually made by chipping and filing (that is, with skilled freehand use of chisels and files). Nuts were rare; metal screws, when made at all, were usually for use in wood. Metal bolts passing through wood framing to a metal fastening on the other side were ...
Four-point measurement of resistance between voltage sense connections 2 and 3. Current is supplied via force connections 1 and 4. In electrical engineering, four-terminal sensing (4T sensing), 4-wire sensing, or 4-point probes method is an electrical impedance measuring technique that uses separate pairs of current-carrying and voltage-sensing electrodes to make more accurate measurements ...
The best-known bridge circuit, the Wheatstone bridge, was invented by Samuel Hunter Christie and popularized by Charles Wheatstone, and is used for measuring resistance. It is constructed from four resistors, two of known values R 1 and R 3 (see diagram), one whose resistance is to be determined R x, and one which is variable and calibrated R 2.
In manufacturing, threading is the process of creating a screw thread.More screw threads are produced each year than any other machine element. [1] There are many methods of generating threads, including subtractive methods (many kinds of thread cutting and grinding, as detailed below); deformative or transformative methods (rolling and forming; molding and casting); additive methods (such as ...
The earliest rail chairs, made of cast iron and introduced around 1800, were used to fix and support cast-iron rails at their ends; [2] they were also used to join adjacent rails. [ 35 ] In the 1830s rolled T-shaped (or single-flanged T parallel rail ) and I-shaped (or double-flanged T parallel or bullhead ) rails were introduced; both required ...
A Flinders bar is a vertical soft iron bar placed in a tube on the fore side of a compass binnacle. The Flinders bar is used to counteract the vertical magnetism inherent within a ship and is usually calibrated as part of the process known as swinging the compass , where deviations caused by this inherent magnetism are negated by the use of ...