THE purpose of this paper is to illustrate some of the consequences of neglecting historical method when studying and writing the history of science. For in such a task history, quite as much as science, must be given its due. The reason is obvious. Whatever else it may be, the history of science is first of all a field of history. To cultivate it effectively, historical scholarship is indispensable. As in any serious historical enterprise, the most essential tools are accordingly (...) systematic bibliography, external and internal criticism, and historiography, by which is here meant the logical organization of historical data and the writing of history. (shrink)

Leeuwenhoek's observations relating to animal population, though scattered through many letters written during a period of over forty years, when seen in toto, were important contributions to the subject now known as animal demography. He maintained enough contact with other scientists to have received encouragement and some helpful suggestions, but the language barrier and the novelty of doing microscopic work forced him to be resourceful, inventive, and original. His multifarious investigations impinged upon population biology before he discovered a direct interest (...) in it. He devised methods for estimating numbers of animalcules, and then he went on to estimate the population of the world. His interest in reproduction was an important avenue by which he approached the subject of reproductive capacity. Other important approaches were his studies of growth, longevity, and life histories. He discovered relationships between aspects of the life history, longevity, and reproductive capacity of several species of insects, notably calanders, scavenger flies, crane flies, aphids, and lice. An important feature of these investigations were the arithmetical calculations which he made of reproductive potentials. In spite of several limitations, these calculations were an important innovation to the study of animal population. In his later years, his investigations came more and more within the sphere of ecology. He made the first significant observations on food chains. It is especially interesting that fish were the subject of these observations, because it was not until the latter half of the nineteenth century that scientists realized that fish ultimately depend upon phytoplankton.These accomplishments did not pass unnoticed. Although Leeuwenhoek never synthesized his scattered observations concerning population, his originality and perception were appreciated by outstanding biologists of the eighteenth century. The important discussions of population biology by Réaumur, Buffon, and Bonnet all derived inspiration and assistance from the writings of Leeuwenhoek.73 This ingenious Fellow of the Royal Society, “by detecting through diligent application and scrutiny the mysteries of Nature and the secrets of natural philosophy,”74 became one of the founders of animal demography. (shrink)

The years between 1660 and 1800 were important ones in the study of light. For most of the period the work, especially in this country, was largely dominated by the theories advanced by Newton; unfortunately the protagonists of these theories were much more rigid in their approach than was Newton himself. There was, in effect, almost a century of ‘rear-guard actions’ to maintain the corpuscular theory at all costs.Fortunately, the advance of geometrical optics and the design of optical instruments was (...) not retarded to a very great degree by this partisan approach. The workers in these fields were not, as a rule, too involved in speculation, and worked largely empirically.Some of the modifications to the original corpuscular theory are interesting. Attempts were made to explain, with varying degrees of success, total internal reflection, dispersion, interference effects, diffraction and phosphorescence. Considerable speculation about the velocity of light occurred in connection with these topics. At the same time, wave theories never completely died out and, although they were not developed until the early part of the nineteenth century, their influence was felt even in this country. (shrink)

As early as 1670 Isaac Barrow and Isaac Newton, at Cambridge, were aware of the production of astigmatism by oblique pencils of rays on a spherical lens. Thomas Young and G. B. Airy independently discovered ocular astigmatism. By viewing the image of objects reflected on the anterior surface of the cornea, the cornea may be examined for any defects of its surface . The corneal “reflex” had been examined as early as 1619 by Christoph Scheiner, and as a “clinical” test, (...) by using a candle flame, by David Brewster . An instrument for examining the anterior surface of the cornea for the detection of abnormality was first invented by Henry Goode of Cambridge University. Antonio Plácido, formerly credited with the invention, independently invented a keratoscope in 1880. Correspondence of Plácido and Emile Javal reveals that Placido invented the photo-keratoscope, formerly attributed to Allvar Gullstrand in Sweden. Javal is credited with the first description of the application of a photo-keratoscope in a specific case of ocular abnormality. (shrink)