The Harold C. Ernst Collection of Portable Sundials

A catalog of sundials from the Harold C. Ernst Collection of Portable Sundials, and a handy reference book on the subject of portable sundials. The sundial is the most ancient scientific instrument to come down to us unchanged. As such it is deserving of a better position in life than that of an ornament. It has played a vital part in the life of man for many thousands of years, and even today it serves us well where the mechanical watch fails. The authors particularly draw attention to the system of classifying, labeling, and cataloging sundials, described in Chapter II. This is the first attempt to bring order out of confusion in sundials

Reconstruction of vertical and L-shaped ancient Egyptian sundials and methods for measuring time

The article presents the results of the study of design features of vertical and L-shaped ancient Egyptian sundials. With the help of astronomical methods were developed their models, based on which the reconstruction of a sundial was held. Also, the original scheme is a simple way to fairly precise of measurement of time with them has been developed. Large urgency of the task due to the lack of similar models and schemes to date. Model offered by us, which describes the vertical sundial, is a vertical sundial, with a sloping gnomon, which takes into account latitude of area. It is based on the assumption of the existence in ancient Egypt representations about an hour (and a half hour) of equal duration throughout the day, does not depend on the time of year. Offered by us model is characterized by marking hour lines from 6 to 12 hours after each hour. From 12 to 12.5 hours produced displacement in the markup of hour lines on half an hour, then the markup is repeated every hour. As a consequence, the reconstruction of the vertical sundials, we have developed and proposed a model that describes the design features and operation of the L-shaped sundials of two types. They had to work together with the inclined gnomon, like vertical sundials or directly with vertical sundials. In this case, L-shaped sundials can complement vertical sundials, providing an opportunity to read the caption to hour markers and interpret the indications of vertical sundials because vertical sundials inscription missing. The article also describes explanation of the inscriptions from the tomb of Seti I, long intriguing researchers. It is proved that the inscription contains the length of the intervals between adjacent markers L-shaped sundial of the second type, where the first interval corresponds to a half of hour. Keywords: sundial, model, astronomical methods, archaeoastronomy, ancient Egypt.Comment: Coefficient in the formula 2 rectified on page

Diplomatic devices : the social lives of foreign timepieces in late sixteenth- and early seventeenth-century Japan

The present paper explores the social lives of European timepieces as a particular set of objects in late sixteenth- and early seventeenth-century Japan, when the archipelago first encountered the “Southern Barbarians” from Portugal and Spain. Rather than viewing them solely as instruments of time measurement or as decorative objects, I discuss clocks as actors that moved within networks of exchange primarily between Europe and Japan, but also, significantly, within East Asia and Japan itself. Along their trajectory, these devices assumed shifting and at times contradictory meanings for various actors; this is particularly true in view of the fundamental clash between European and Japanese systems of time-reckoning, which essentially rendered early European-style mechanical clocks ‘timeless’ in Japan, with its equinoctial system of variable hours. For Jesuit missionaries and foreign emissaries who brought these early devices to Japan, they were timekeepers, objects of ecclesiastical use, paragons of European ingenuity, and above all diplomatic tools that granted access and established connections with the Japanese ruling elite. For the Japanese, by contrast, these global objects assumed meaning within their highly developed local gift-culture as desirable novelty items, particularly within the socially volatile environment of the unification of the country under Tokugawa control. My contention is that these microhistories of exchange help us understand why mechanical clocks did not have the same ‘revolutionary’ effect on time-reckoning in Japan as they did in Europe; the social lives of these objects strikingly illustrate the power imbalances in diplomatic negotiations that made Japan impervious to coercion by the European powers

Copernicus's Heliograph at Olsztyn -- the 500th Anniversary of a Scientific Milestone

Exactly 500 years ago, Nicolaus Copernicus drew a lattice of lines on a panel above the doorway to his rooms at Olsztyn Castle, then in the Bishopric of Warmia. Although its design has long been regarded as some kind of reflecting vertical sundial, the exact astronomical designation of the lines and related measuring techniques remained unknown. Surprisingly, Copernicus did not refer to his new observational methods in his principal work, \textit{De Revolutionibus}. A data analysis of a 3D model of the panel has, at last, solved the mystery: Copernicus created a new type of measuring device -- a heliograph with a non-local reference meridian -- to precisely measure ecliptic longitudes of the Sun around the time of the equinoxes. The data, 3D model and modeling results of our analysis are open access and available in the form of digital (Jupyter) notebooks

Vortexje - An Open-Source Panel Method for Co-Simulation

This paper discusses the use of the 3-dimensional panel method for dynamical system simulation. Specifically, the advantages and disadvantages of model exchange versus co-simulation of the aerodynamics and the dynamical system model are discussed. Based on a trade-off analysis, a set of recommendations for a panel method implementation and for a co-simulation environment is proposed. These recommendations are implemented in a C++ library, offered on-line under an open source license. This code is validated against XFLR5, and its suitability for co-simulation is demonstrated with an example of a tethered wing, i.e, a kite. The panel method implementation and the co-simulation environment are shown to be able to solve this stiff problem in a stable fashion.Comment: 13 pages, 8 figure

'BioNessie(G) - a grid enabled biochemical networks simulation environment

The simulation of biochemical networks provides insight and understanding about the underlying biochemical processes and pathways used by cells and organisms. BioNessie is a biochemical network simulator which has been developed at the University of Glasgow. This paper describes the simulator and focuses in particular on how it has been extended to benefit from a wide variety of high performance compute resources across the UK through Grid technologies to support larger scale simulations

Extended Lifetime in Computational Evolution of Isolated Black Holes

Solving the 4-d Einstein equations as evolution in time requires solving equations of two types: the four elliptic initial data (constraint) equations, followed by the six second order evolution equations. Analytically the constraint equations remain solved under the action of the evolution, and one approach is to simply monitor them ({\it unconstrained} evolution). The problem of the 3-d computational simulation of even a single isolated vacuum black hole has proven to be remarkably difficult. Recently, we have become aware of two publications that describe very long term evolution, at least for single isolated black holes. An essential feature in each of these results is {\it constraint subtraction}. Additionally, each of these approaches is based on what we call "modern," hyperbolic formulations of the Einstein equations. It is generally assumed, based on computational experience, that the use of such modern formulations is essential for long-term black hole stability. We report here on comparable lifetime results based on the much simpler ("traditional") $\dot g$ - $\dot K$ formulation. We have also carried out a series of {\it constrained} 3-d evolutions of single isolated black holes. We find that constraint solution can produce substantially stabilized long-term single hole evolutions. However, we have found that for large domains, neither constraint-subtracted nor constrained $\dot g$ - $\dot K$ evolutions carried out in Cartesian coordinates admit arbitrarily long-lived simulations. The failure appears to arise from features at the inner excision boundary; the behavior does generally improve with resolution.Comment: 20 pages, 6 figure