Voltaire's contribution to the spread of newtonianism—I. letters from england: Les lettres philosophiques

Part I: In early middle life Voltaire had a considerable interest in science, provoked by a visit to London and by learning at close range of the work of men like Newton and Locke, which had developed in a more scientific direction than that of the Cartesianism then current and almost universal in France. With courage, and to the chagrin of his own countrymen, Voltaire advocated the empirically based work or Natural Philosophy of Newton. He published a thin volume known as the Letters from England, 1733 or Les Lettres Philosophiques in 1734, which brought him into conflict with the officialdom of France and then exile. We describe and discuss the contents and background of this very influential book and entertain some comments made about it, then and since. For us, the philosopher John Locke here comes to play a larger role in this subject than he normally assumes in discussions of Newtonianism. We endeavour to show too the roles played by Jacques Rohault and Samuel Clarke.Part II: Resting on Part I we discuss Voltaire's larger volume of 1738, on Elements of Newton's Philosophy. Mme Emilie du Châtelet (or Chastelet) was enormously influential in the writing of it and indeed is often credited as having been truly a co-author. She made a translation of Newton's Principia which was posthumously and openly published for her in 1759, by Clairaut, 10 years after her death. Mme du Châtelet and Voltaire were greatly responsible for spreading Newton's views in France; wrote Miller in [1(a)], “... he conquered the mind of the Continent by popularising Newton”. We review the translation of the Elements, its reception, and again describe the background of the period. Our subject is a little-known story that might well have been an entertaining and timely lecture for students of mechanics three years ago on the occasion of the tercentenary of the Principia [1(b)].     

Long rod penetration models—Part II. Extensions to the hydrodynamic theory of penetration

The modified hydrodynamic theory of penetration is extended to take account of the transient, plastic-wave dominated and after-flow phases of penetration. It is also indicated how a more detailed flow field model of the primary phase of penetration leads to the modified Bernoulli equation and a relationship between the dynamic yield strength and the strength factors R_t and Y_p. The effect of the decelerative motion on the modified Bernoulli equation is also briefly examined. Finally, the theory is compared with experimental results of previous papers.     

An approach to the displacement analysis of spatial mechanisms—II : Mechanisms with High Degree Equations

The method of displacement analysis introduced in Part I of the work is shown applied here to 5- and 6-link mechanisms that yield 8th degree input-output equations. The derivation for 6-link 5R-C mechanisms is also indicated, to the extent of showing that extraneous roots are avoided.     

The response of wire rope strands to axial tensile loads—Part II. Comparison of experimental results and theoretical predictions

Carefully instrumented tests were performed on straight single steel strands of seven-wire construction subjected to axial loads and with various end restraints. The strands have a practical range of lay angles between 9.2 and 17.0° with core and helical wire diameters of 3.94 and 3.73 mm, respectively. A mathematical model of a strand was developed to explore the change of helix angle under load, Poisson ratio effects in wires, wire flattening under interwire pressure and the effect of friction between the core and helical wires. A companion article (Part II) [Int. J. Mech. Sci. 29, 621–636 (1987)] compares the theoretical predictions with previously published analytical work and with the corresponding experimental results reported in this article.     

The plane-strain general yielding of notched members due to combined axial force and bending—II: Deep circular notches

The slip-line fields proposed by Green for the plane-strain general yielding of notched plates in pure bending are generalized to provide solutions for notched plates subjected to combined axial force and bending. Deep symmetrical circular notches and single circular notches are considered. For notched plates subjected to arbitrary combinations of axial force and bending, two constraint factors are obtained, T₁ due to the axial force and M₁ due to the bending moment. These constraint factors are shown to have characteristic relationships on the T₁−M₁ plane for the single notched plate and the symmetrically notched plate. The derivations of these general yielding loci are described in detail and the statical and kinematical limitations of the slip-line fields are discussed. Finally it is demonstrated that the corresponding strain-rate vectors are normal to these loci and that, therefore, these loci can be regarded as plastic potentials.     

The application of heat‐deproteinization to the morphological study of cortical bone: A contribution to the knowledge of the osteonal structure

Observation of heat‐deproteinized cortical bone specimens in incident light enabled the high definition documentation of the osteonal pattern of diaphyseal Haversian bone. This prompted a study to compare these images with those revealed by polarized light microscopy, carried out either on decalcified or thin, undecalcified, resin‐embedded sections. Different bone processing methods can reveal structural aspects of the intercellular matrix, depending on the light diffraction mode: birefringency in decalcified sections can be ascribed to the collagen fibrils orientation alone; in undecalcified sections, to both the ordered layout of collagen and the inorganic phase; in the heat‐deproteinized samples, exclusively to the hydroxyapatite crystals aggregation mode. The elemental chemical analysis documented low content of carbon and hydrogen, no detectable levels of nitrogen and significantly higher content of calcium and phosphorus in heat‐deproteinized samples, as compared with dehydrated controls. In both samples, the X‐ray diffraction (XRD) pattern did not show any significant difference in pattern of hydroxyapatite, with no peaks of any possible decomposition phases. Scanning electron microscopic (SEM) morphology of heat‐deproteinized samples could be documented with the fracturing technique facilitated by the bone brittleness. The structure of crystal aggregates, oriented in parallel and with marks of time periods, was documented. Comparative study of deproteinized and undecalcified samples showed that the matrix inorganic phase did not undergo a coarse grain thermal conversion until it reached 500°C, maintaining the original crystals structure and orientation. Incident light stereomicroscopy, combined with SEM analysis of deproteinized bone fractured surfaces, is a new enforceable technique which can be used in morphometric studies to improve the understanding of the osteonal dynamics. Microsc. Res. Tech. 79:691–699, 2016. © 2016 Wiley Periodicals, Inc.     

The application of Chace's vector equations to the computer generation of Burmester curvesL'Application des equations vectirielles de chase a la generation par ordinateur des courbes de Burmester

A vector method for the generation of Burmester curves by computer is described. It is based on the graphical method due to L. Burmester and applies Chace's vector equations (Case 1 and Case 3) for solving vector triangles. Stevensen's VECTOR and CHACE subroutine subprograms are used in the computer program. An application of the program to the problem of guiding the boom of a front loader is discussed.