...remained relatively unchanged to this day, with only a few modern additions. To create a blown glass object, the glassworker blows air through a metal pipe, expanding molten glass by slowly forcing in a small amount of air. This is possible because of the atomic structure of hot glass – when heated, the atoms are held together by chemical bonds in a random and chaotic network, causing the hot glass to remain in a viscous state and slowly harden as it cools, therefore facilitating its expansion due to air. There are two techniques that modern glassworkers use, free-blowing and mold-blowing, and each utilizes a metal pipe in the creation process. In free-blowing, the glassworker blows many short and quick breaths of air into a molten shape of glass which has been wrapped around the end of a blowpipe – this is known as a “gather.” (Habatat Galleries, 2018) The short bursts of air form an elastic skin on the interior of the glass, to effectively cool the inside of the glass at the same rate as the outside of the glass cools naturally, in order for the inside and outside to reach a uniform texture. Once this has been achieved, the glassworker spins, manipulates, and swings the blowpipe to reach the desired shape. Skilled artists are able to create nearly any shape or form with this method, but despite sounding relatively simple, this is very difficult to achieve, as the glassworker must simultaneously rotate and swing the blowpipe while blowing through the pipe to maintain the temperature...
Words: 1698 - Pages: 7
...The History of Thermostats By Spring Quarter 2014 THE HISTORY OF THERMOSTATS Definition of a thermostat; A thermostat is a component of a control system which senses the temperature of an area so the area's temperature is maintained near a desired setpoint. The name is derived from the Greek words thermos or "hot" and statos or "a standing". Cornelius Drebble (1572-1634), a Dutch engraver and glassworker, invented the first thermostat in the early 1600’s, which was the first the automatic temperature control device. The thermostat was spawned from an elaborate toy he designed which operated on the basis of changes in the atmospheric pressure and temperature. The thermostat was created for a chicken and duck egg incubator and was the first mercury device that would hold the temperature constant. Around the same time frame, Drebble also invented the first self-regulating oven damper that was also mercury controlled. As the temperature went up, the damper would be closed by a primitive mercury switch. When the temperature cooled, the mercury would contract and open the damper adding oxygen to increase the fire. Before thermostats, the only way we could control the temperature of a home was to manually open or close the fireplace damper/ flu or open a window to regulate heat. Albert Butz, (1849-1905) was a Swiss born inventor, businessman and the father of the modern automated control industry, made a resemblance of today’s thermostat in 1885. It had an electric...
Words: 1179 - Pages: 5
...blowing, glassmakers have been making use of the same instruments to figure, control, and decorate liquid glass, in fact the essential innovation of non industrial glassmaking and the apparatus utilized have not changed. [1] Current suggestions about manufacturing in the ancient world indicate that glass was produced from raw materials in large primary batches and handed out as raw lumps or ingots to secondary workshops where it was formulated into vessels and other artefacts. The batch would consist of a mixture of fresh glass and cullet (glass collected for recycling). These materials would usually be made up of a range of compositions, which would be homogenized upon melting to give a characteristic composition for the batch. [10] The glassworkers would start off by introducing lumps or ingots of fresh primary glass and replenish the melting pot with cullet as time goes by. Due to this, each cullet batch which is added would modify the composition of the glass being worked. With regards to the technique of blowing glass, the glass maker makes use of a blowpipe, used to gather liquid glass, and blows through the pipe so as to inflate the object. In order to support the artifact in the glass furnace, a strong metal pole is known as a pontil is connected to the base of the vessel, and is cut off and polished after firing is done. Wooden pieces, jacks, and shears are used to shape an article. The gaffer controls the shape and thickness by warming the parison at the heater and...
Words: 1573 - Pages: 7
...Labor Unions in the United States Posted Mon, 2010-02-01 17:21 by Anonymous Gerald Friedman, University of Massachusetts at Amherst Unions and Collective Action In capitalist labor markets, which developed in the nineteenth-century in the United States and Western Europe, workers exchange their time and effort for wages. But even while laboring under the supervision of others, wage earners have never been slaves, because they have recourse from abuse. They can quit to seek better employment. Or they are free to join with others to take collective action, forming political movements or labor unions. By the end of the nineteenth century, labor unions and labor-oriented political parties had become major forces influencing wages and working conditions. This article explores the nature and development of labor unions in the United States. It reviews the growth and recent decline of the American labor movement and makes comparisons with the experience of foreign labor unions to clarify particular aspects of the history of labor unions in the United States. Unions and the Free-Rider Problem Quitting, exit, is straightforward, a simple act for individuals unhappy with their employment. By contrast, collective action, such as forming a labor union, is always difficult because it requires that individuals commit themselves to produce "public goods" enjoyed by all, including those who "free ride" rather than contribute to the group effort. If the union succeeds, free riders...
Words: 10531 - Pages: 43
