The attempt to narrow the general discourse of the problem of error and to focus it on the specific problem of experimental error may be approached from different directions. One possibility is to establish a focusing process from the standpoint of history; such an approach requires a careful scrutiny of the history of science with a view to identifying the juncture when the problem of experimental error was properly understood and accounted for. In a study of this kind one would have to examine the evolution of the method of experimentation and related topics so that clear criteria would underlie the analysis.

It has long been recognized that unnecessary cruelty to animals was held to be morally wrong by many classical moralists and medieval scholastics, and was echoed repeatedly in the early-modern period, though not necessarily reflecting any particular concern for animals, but rather to indicate the supposed brutalizing effects on the human character. The prevalence of the more radical view that cruelty to animals was wrong regardless of human consequences has only been dealt with comparatively recently, in the pioneering work of Keith Thomas with regard to early-modern England. Thomas suggested that a remarkably constant and coherent argument underpinned the bulk of pamphleteering and preaching against animal cruelty in the period; man was entitled to domesticate animals and kill them for food and clothing but not to cause them unnecessary suffering. While wild animals could be killed for food or in self-defence, and game and vermin could be hunted, it was deemed wrong to kill only for pleasure. While this position could be found among Protestants of many different persuasions, the particular focus of successive campaigners changed over time. Preceding the Civil War the attack was concentrated on cock-fighting, bear-baiting and the ill-treatment of domestic animals; in the later seventeenth century it broadened out to include the caging of wild birds, brutal methods of slaughter, hare-hunting and vivisection.

As sociologists learn more about how scientific knowledge is created, they give historians the opportunity to rework their accounts from a more contextual perspective. It is relatively easy to do so in areas with large theoretical, cosmological or overtly ideological components. It is more difficult, but equally necessary, to open up very empirical accomplishments, and recent sociological analysis of the process of science gives us some interesting insights. This paper employs some of these on the apparently unpromising subject of the ‘discovery of secular magnetic variation’ in 1634 by the Gresham professor Henry Gellibrand.

Darwin is well known for his wondrously ambiguous rhetoric. The author who used an ‘entangled bank’ as his metaphor for Nature and its complex relationships built up the substance of his text from a corresponding entanglement of unresolved theoretical relations. Ambiguous positions, arguments that seem to fold in on themselves, vacillations, contradictions, and pluralities of explanation suffuse Darwin's science and its constituent metascience. The Origin abounds in ambiguities with regard to the technical features of evolutionary biology. But the domain of ambiguity I wish to address is Darwin's metaphysical stance. I want to approach the question of Darwin and secularization through what might be called the trope of ambiguity. My principle concern is with the origins of that ambiguity. These lie in the conflicting cultural and ideological resources Darwin used to construct the theory of natural selection.

The renowned notebook of the twelfth-century architect Villard de Honnecourt contains some deleted diagrams, which have been studied by Roland Bechmann. An infra-red photograph of a page revealing an erased drawing of a pointed arch is reproduced as Fig. 25, a redrawn diagram is given as Fig. 26 and an enhanced version (with supplementary constructions) is given as Fig. 27. That enhanced version includes a simple geometrical construction of a line AE, with the radius of each of the semi-circles labelled as R.