Al-Khazini in on the development of hydrostatic balance and its functionality

The significance of this chapter is to review the main contributions of al-Khazini in physics and scientific instruments. The methodology adopted in this chapter includes review of available and reliable literatures and data collected from library and internet sources. The main focus of the chapter is to present the work done by previous Muslim scientists on hydrostatics in the determinations of specific gravies of liquid, precious stones, metals and the hydrostatic balance designed and constructed by al-Khazini. Studies have shown that AI-Biruni and AI-Khazini performed the first scientific experimentations in areas of statics and dynamics; this is particularly for determination of specific weights, such as those based on the "theory of balances and weighing". The strict definition for a specific weight is given by AI-Khazini in "The Book of the Balance of Wisdom" and the reminder of the book is devoted to the description of various balances, beginning with balance attributed to Archimedes, proceeding through balances developed by Muslim scholars and concluding with an exhaustive description of the balance which al-Khazini calls "The Balance of Wisdo

Review Article: Gas and vapor sorption measurements using electronic beam balances

The beam balance is one of the oldest known measuring instruments. Until the 20th century, balances had been the most sensitive and precise instruments used for scientific measurements. The original balances used a beam supported at the center with pans hung from cords on both ends. The modern electronic beam balances still resemble those original designs; however, the resolution, accuracy, and capabilities have been significantly improved. This review provides a short introduction to the history of beam balances followed by a detailed description of three gravimetric microbalances manufactured by Hiden Isochema for measuring gas and vapor sorption in a variety of materials

Lines of Credit and Consumption Smoothing: The Choice between Credit Cards and Home Equity Lines of Credit

The author models the choice between credit cards and home equity lines of credit (HELOCs) within a framework where consumers hold lines of credit as instruments of consumption smoothing across state and time. Flexible repayment schemes for lines of credit induce risk-averse consumers with sufficiently high discount rates to underinsure and hold lines of credit instead as a buffer, even when they have access to full and fair insurance markets. Weighing the fixed upfront fees and higher default costs of HELOCs against the advantages of low and income-tax-deductible interest payments, the author finds a threshold level of potential borrowing belowwhich consumers prefer to use credit cards exclusively. Above that threshold, consumers decide touse HELOCs and consolidate all outstanding credit card debt into them; however, a rising probability of default and the resulting loss of equity in the home will put an upper bound on the potential HELOC borrowing that will prevent full debt consolidation.Credit and credit aggregates

An investigation of the behavior of outgassed molecules in thermal vacuums

The objective is to understand how surfaces outgas and how outgassed substances subsequently condense on other surfaces. Preliminary tests produced calculated mass losses that were found to be in reasonable agreement with mass losses determined by weighing the sample before and after testing on analytical balances. However, using test materials with various molecular properties showed characteristic variations in the ratios of calculated total mass loss to experimental loss. These variations indicate that for some molecules energetic barriers to absorption and desorption can exist between outgassed molecules and the surfaces on which they condense

The precision measurement of mass

A method has been described for obtaining the density of air quickly without resort to measurement of the prevailing atmospheric conditions and with accuracy sufficient to enable the correction for the buoyancy of air on a weighing to be made to better than one part per million. The method involves the weighing in air in quick succession of two objects, a hollow cylinder of stainless steel (density 0.5 g./cm.(\u273)) and a solid counterweight of equal mass and area in the form of a stainless steel tube (density 8.11 g./cm.(\u273)). The densities of these objects have been obtained from the volume as determined by high-precision hydrostatic weighing and by measurements of the dimensions and from the mass as determined by weighing in an actual vacuum ( vacuum weighing bottle ). The density of air obtained by weighing this absolute density cylinder and counterweight has been compared to the density calculated from measurements of the atmosphere, made at the same time in a constant temperature room ((+OR-)0.075(DEGREES)) and with high-precision instruments, of the barometric pressure and temperature and gravimetric determination of water and carbon dioxide contents. The density of air determined by the cylinder was 3.4 parts per thousand greater than that calculated from the prevailing conditions. Possible explanations for the discrepancy have been examined with particular reference to the oxygen content of the atmosphere; the discrepancy is left unexplained but it is recommended that for the high-precision measurement of mass that the density of air be measured with a cylinder such as the one described;A method has been proposed for the high-precision determination of the oxygen content of the atmosphere;Modifications of the Mettler single-pan balances have been described to increase capacity and sensitivity and eliminate electrostatic effects;It has been proposed to replace the International Kilogram with a kilogram mass of a corrosion-resistant stainless steel the surface of which has been rendered nonpolar by chemical treatment and to subdivide the kilogram in an actual vacuum using a set of weights constructed on the basis of the Fibonacci sequence. Fabrication of such a set of weights has been started. A mathematical theory has been developed for the calibration of this set in which advantage is taken of the numerous possible cross checks on the experimental work afforded by the characteristics of the Fibonacci numbers

Reflections on a Measurement of the Gravitational Constant Using a Beam Balance and 13 Tons of Mercury

In 2006, a final result of a measurement of the gravitational constant $G$ performed by researchers at the University of Z\"urich was published. A value of G=6.674\,252(122)\times 10^{-11}\,\mbox{m}^3\,\mbox{kg}^{-1}\,\mbox{s}^{-2} was obtained after an experimental effort that lasted over one decade. Here, we briefly summarize the measurement and discuss the strengths and weaknesses of this approach.Comment: 13 pages, 5 figures accepted for publication in Phil. Trans. R. Soc.