La Scala Graduum Caloris de Newton. Una simulación numérica

Sir Isaac Newton, in the Scala graduum Caloris, published in 1701, presented a scale with “the degree of heat” of the bodies which extended the measurements far beyond the values available at that time. To determine it, Newton followed two paths. The first was by using an expansion thermometer with linseed oil as the liquid, whose measurements followed an arithmetical progression, but its maximum was limited by the inflammation of the oil. The second using a completely new method, which consisted of measuring the cooling times of a body previously heated in a small kitchen fire, and relating these times to the temperatures according to a new law, which gave rise to a new scale that followed a geometric progression. Both scales were partially overlapped, allowing him to extend the arithmetic measurements up to more than six times the water boiling point. This new law is known as Newton’s Cooling Law. Here, we intend to carry out a numerical simulation of the hot body cooling process, conjecturing the instruments he may have used and the environmental conditions in which it took place. All this following what Newton himself reflects in his article. We will end with some reflections on the law, which we believe he enunciated in an integral manner.Sir Isaac Newton, en la Scala graduum Caloris, publicada en 1701, presentaba una escala “con el grado de calor” de los cuerpos que extendía las medidas muy por encima de los valores disponibles en la época. Para determinarla, Newton siguió dos caminos. El primero usando un termómetro de dilatación con aceite de linaza como líquido, cuyas medidas seguían una progresión aritmética, pero cuyo máximo estaba limitado por la inflamación del aceite. El segundo, por un método completamente nuevo, que consistía en medir los tiempos de enfriamiento de un cuerpo previamente calentado en una pequeña cocina de carbón, y relacionar esos tiempos con las temperaturas según una nueva ley, lo que daba lugar a una escala que seguía una progresión geométrica. Ambas escalas se solapaban parcialmente, lo cual le permitió extender las medidas aritméticas hasta más de seis veces el punto de ebullición del agua. Esa nueva ley se conoce como “Ley de enfriamiento Newton”. Aquí, pretendemos realizar una simulación numérica del proceso de enfriamiento del cuerpo caliente, conjeturando los instrumentos que pudo haber usado y las condiciones ambientales en que se realizó. Todo ello siguiendo lo que el propio Newton refleja en su artículo. Se terminará con unas reflexiones sobre la ley, que estimamos que la enunció en forma integral

Se analiza la teoría de Jorge Juan sobre la resistencia fluídica, tal como la expone en el Examen

The Jorge Juan theory on fluid resistance is analysed as stated in the Examen Marítimo. The theoretical basis and applications are studied, these range from flat plates to ship hull and sails. The article concludes with a revision of what Juan considers to be its experimental basis and possible forerunners of his theory are traced.<br><br>Se analiza la teoría de Jorge Juan sobre la resistencia fluídica, tal como la expone en el Examen Marítimo. Se estudian las bases teóricas y sus aplicaciones, desde placas planas hasta cacos y velas de buques. Se concluye con una revisión de lo que Juan considera sus fundamentos experimentales y se rastrean los posibles antecedentes de su teoría

The genesis of fluid mechanics, 1640-1780

Fluid Mechanics, as a scientific discipline in a modern sense, was established between the last third of the 17th century and the first half of the 18th one. This book analyses its genesis, following its evolution along two basic lines of research, which have been named the "problem of resistance" and the "problem of discharge". This approach highlights the existence of a remarkable experimental aspect in the aforementioned research lines, together with their link with problems of a practical nature, such as ballistics, hydraulics, fluid-using machines or naval theory. On the other hand, although previous studies usually present fluid mechanics from the point of view of mathematics, this is complemented here by an engineering viewpoint; gathering attempts made in the beginnings of fluid mechanics to see if the theory was capable of productive application in practical terms. This is nothing unusual in a time where the quality of knowledge and skill is measured largely by its usefulness. (c) Universidad Nacional de Education a Distancia, La Génesis de la Mecanica de los Fluidos (1640-1780) ISBN 84-362-3439-1