A pantograph is a mechanical linkage connected in a manner based on parallelograms so that the movement of one pen, in tracing an image, produces identical movements in a second pen. If a line drawing is traced by the first point, an identical, enlarged, or miniaturized copy will be drawn by a pen fixed to the other. Using the same principle, different kinds of pantographs are used for other forms of duplication in areas such as sculpture, minting, engraving, and milling.
A galvanometer is an electromechanical instrument used for detecting and indicating an electric current. A galvanometer works as an actuator, by producing a rotary deflection of a pointer, in response to electric current flowing through a coil in a constant magnetic field. Early galvanometers were not calibrated, but improved devices were used as measuring instruments, called ammeters, to measure the current flowing through an electric circuit.
Benjamin Banneker was a free African-American almanac author, surveyor, landowner and farmer who had knowledge of mathematics and natural history. Born in Baltimore County, Maryland, to a free African-American woman and a former slave, Banneker had little or no formal education and was largely self-taught. He became known for assisting Major Andrew Ellicott in a survey that established the original borders of the District of Columbia, the federal capital district of the United States.
A graphics tablet is a computer input device that enables a user to hand-draw images, animations and graphics, with a special pen-like stylus, similar to the way a person draws images with a pencil and paper. These tablets may also be used to capture data or handwritten signatures. It can also be used to trace an image from a piece of paper which is taped or otherwise secured to the tablet surface. Capturing data in this way, by tracing or entering the corners of linear polylines or shapes, is called digitizing.
Duplicating machines were the predecessors of modern document-reproduction technology. They have now been replaced by digital duplicators, scanners, laser printers and photocopiers, but for many years they were the primary means of reproducing documents for limited-run distribution. The duplicator was pioneered by Thomas Edison and David Gestetner, with Gestetner dominating the market up until the late 1990s.
Charles Willson Peale was an American painter, soldier, scientist, inventor, politician and naturalist. He is best remembered for his portrait paintings of leading figures of the American Revolution, and for establishing one of the first museums in the United States.
A scale or balance is a device to measure weight or mass. These are also known as mass scales, weight scales, mass balances, weight balances.
The parallel motion is a mechanical linkage invented by the Scottish engineer James Watt in 1784 for the double-acting Watt steam engine. It allows a rod moving practically straight up and down to transmit motion to a beam moving in an arc, without putting significant sideways strain on the rod.
A swingarm, or "swinging arm" (UK), originally known as a swing fork or pivoted fork, is a single or double sided mechanical device which attaches the rear wheel of a motorcycle to its body, allowing it to pivot vertically. The main component of the rear suspension of most modern motorbikes and ATVs, it holds the rear axle firmly, while pivoting to absorb bumps and suspension loads induced by the rider, acceleration, and breaking.
Watt's linkage is a type of mechanical linkage invented by James Watt in which the central moving point of the linkage is constrained to travel on a nearly straight line. It was described in Watt's patent specification of 1784 for the Watt steam engine.
A chart recorder is an electromechanical device that records an electrical or mechanical input trend onto a piece of paper. Chart recorders may record several inputs using different color pens and may record onto strip charts or circular charts. Chart recorders may be entirely mechanical with clockwork mechanisms, electro-mechanical with an electrical clockwork mechanism for driving the chart, or entirely electronic with no mechanical components at all.
The Kitchen rudder is the familiar name for "Kitchen's Patent Reversing Rudders", a combination rudder and directional propulsion delivery system for relatively slow speed displacement boats which was invented in the early 20th century by John G. A. Kitchen of Lancashire, England. It turns the rudder into a directional thruster, and allows the engine to maintain constant revolutions and direction of drive shaft rotation while altering thrust by use of a control which directs thrust forward or aft. Only the rudder pivots; the propeller itself is on a fixed shaft and does not.
A jack is a mechanical lifting device used to apply great forces or lift heavy loads. A mechanical jack employs a screw thread for lifting heavy equipment. A hydraulic jack uses hydraulic power. The most common form is a car jack, floor jack or garage jack, which lifts vehicles so that maintenance can be performed. Jacks are usually rated for a maximum lifting capacity. Industrial jacks can be rated for many tons of load.
A balanced-arm lamp, sometimes called a floating arm lamp, is a lamp with an adjustable folding arm which is constructed such that the force due to gravity is always counteracted by springs, regardless of the position of the arms of the lamp. Many lamp brands as well as other devices, such as drawing boards, use this principle.
Technical lettering is the process of forming letters, numerals, and other characters in technical drawing. It is used to describe, or provide detailed specifications for, an object. With the goals of legibility and uniformity, styles are standardized and lettering ability has little relationship to normal writing ability. Engineering drawings use a Gothic sans-serif script, formed by a series of short strokes. Lower case letters are rare in most drawings of machines.
Astronomical rings, also known as Gemma's rings, are an early astronomical instrument. The instrument consists of three rings, representing the celestial equator, declination, and the meridian.
A physiognotrace is an instrument, designed to trace a person's physiognomy to make semi-automated portrait aquatints. It was invented in France in 1783–84 and popular for some decades. The sitter climbed into a wooden frame, sat and turned to the side to pose. A pantograph connected to a pencil produced within a few minutes a "grand trait", a contour line on a piece of paper. With the help of a second scaling down pantograph, the basic features of the portrait were transferred from this sheet in the form of dotted lines to a copper plate which had previously been prepared with a ground for etching. One week later the sitter received an etched plate and twelve little prints. Not only this device, but also the aquatint prints, are called physionotraces.
A trammel of Archimedes is a mechanism that generates the shape of an ellipse. It consists of two shuttles which are confined ("trammelled") to perpendicular channels or rails and a rod which is attached to the shuttles by pivots at fixed positions along the rod.
A leg mechanism is a mechanical system designed to provide a propulsive force by intermittent frictional contact with the ground. This is in contrast with wheels or continuous tracks which are intended to maintain continuous frictional contact with the ground. Mechanical legs are linkages that can have one or more actuators, and can perform simple planar or complex motion. Compared to a wheel, a leg mechanism is potentially better fitted to uneven terrain, as it can step over obstacles.
A five-bar linkage is a two degree-of-freedom mechanism that is constructed from five links that are connected together in a closed chain. All links are connected to each other by five joints in series forming a loop. One of the links is the ground or base. This configuration is also called a pantograph, however, it is not to be confused with the parallelogram copying linkage pantograph.
