Iuhps La Commission Des Instruments

SCIENTIFIC INSTRUMENT COMMISSION o/«*« IUHPS 1.1 LA COMMISSION DES INSTRUMENTS SCIENTIFIQUES <fcUIHPS Title / litre Sir William Logan's Petrographic Microscope? Author / Auteur Peter H. von Bitter Affiliation / Affiliation Department of Palaeobiology, Royal Ontario Museum Address / Adresse 100 Queen's Park Toronto ON M5S 2C6 Canada Abstract / Resume A petrographic microscope with rotating stage signed Nachet, 17 rue St. Saverin, Paris, in the collections of the Geological Survey of Canada, has, in recent years, been identified and publicized as having belonged to and been used by Sir William Logan, the founding director of that organization. This interpretation of ownership and/or use by Logan seems unlikely. 1) Although polarizing features began to be added to microscopes in the 1830 s and 1840s and 2) H. Clifton Sorby, F. E. Zirkel and others pioneered the study of the optical characteristics of minerals in thin rock sections in the mid-1800s and 3) M. Des Cloizeaux developed a polarizing mineralogical microscope as early as 1864, the modern petrographic microscope with a rotating stage was not constructed by R. Fuess of Berlin for H. Rosenbusch until 1873. Jean Alfred Nachet (1831-1908), famous Parisian instrument maker, probably adapted the ideas that were being disseminated by the mineralogical community of Germany and France in the 1870s to develop a petrographic microscope with unique Nachet design features. That this development did not take place until the mid- to late 1870s is shown by the 1876 publication date of Rosenbusch's design, by the earliest published descriptions of Nachet s petrographic microscope dated 1880 and 1881, and by the fact that the earliest available Nachet sales catalogue to show petrographic microscopes was for the year 1881. Sir William Logan resigned from the Geological Survey of Canada in 1869 at the age of 70 and died in 1875. SCIENTIFIC INSTRUMENT COMMISSION «/«« IUHPS 1.2 LA COMMISSION DES INSTRUMENTS SCIENTIFIQUES deUOJPS Title / litre A 19th Century Surveyor's Compass Author / Auteur I.E. Kennedy and Mark MacKenzie Affiliation / Affiliation resp.: University of Saskatchewan and Saskatchewan Western Development Museum Address / Adresse Saskatoon, Saskatchewan Canada Abstract / Resume During the 19th century, surveying in many regions of Canada was carried out with a surveyor's compass (circumferentor) and chain. A number of surveyors could not afford either the more expensive engineer's level or an engineer's transit. Scientists in the latter half of the century became aware of and concerned with the inherent errors associated with the field use of the surveyor's compass. W.B. lack at Fredericton and W.F. King at Ottawa established "standards laboratories" to assist surveyors in overcoming some of the difficulties associated with the use of.the compass in the field. The number of circumferentors to be found today in Canada s museums is not excessive. Prior to 1980, the late Dr. B .W. Currie made a gift to the Physics Department, University of Saskatchewan, of an early 19th century surveyor's compass. A limited conservation treatment is required for this compass before displaying it to the public as an artifact. This circumferentor was designed and manufactured as a practical instrument for use in field surveying. A close examination of this compass yields details of small volume production of utilitarian scientific instruments of the early 19th century. Physical scars and marks may be the result of field repairs. The combination of organic hair in the sighting reticules, as well as the materials used in the degree dial and jewel bearing, broadens the composite materials nature of this artifact and places constraints on the preservative treatments considered feasible. Contamination on the needle in the form of finger print patterns is an example of "patina vile" which should be removed and stabilized. The best process for doing so may jeopardize future field trials of this artifact. Such considerations must be evaluated prior to finalizing conservation treatment. Though relatively simple, the treatment will be decided upon by assessing the academic potential offered by this compass, along with its eventual curatorial exhibit possibilities. SCIENTIFIC INSTRUMENT COMMISSION <>/*« IUHPS 1.3 LA COMMISSION DBS INSTRUMENTS SCIENTIFIQUES </«UIHPS Title / Titre Direct and Indirect Methods of Measurements: Invention and Development of the Analytical Plotter in Canada. Author / Auteur Teodor I. Blachut Affiliation / Affiliation National Research Council of Canada (retired) Address / Mresse 61 Rothwell Dr. Gloucester ON K1)7G7 Canada Abstract / Resume When discussing measurements we usually have in mind direct measurements in "natural space". This means that, using appropriate tools, we perform measurements of the actual object to establish its form and dimensions. In many cases the object may be very complex and direct measurements may not provide a satisfactory answer, e.g. the human body. Precise determination of its shape through direct measurements is almost impossible. Other examples of difficulties in direct measurement includes an object that is changing shape, is in motion, or is inaccessible, e.g. steep mountains, clouds, wave, etc.. Applicability of direct measurements is therefore very limited. Indirect measurements are made when a physical or abstract model of the actual object is submitted to precise measurements. I am referring to techniques and processes that together constitute the discipline of Photogrammetry. The main application of photogrammetry is in mapping. However, the definition of photogrammetry as "the use of aerial photographs for mapping" is wrong and damaging to photogrammetry. Rather, the construction of virtual or physical models is based on the use of photographic images of precisely known geometry. The instruments used for measurements or plotting of the models require very high accuracy, i.e. of the order of single microns (micro- millimetres). Analogue plotters. Characteristics, performance and limitations. Reaching the limit of practical possibility. Analytical photogrammetry. To overcome the limitations of the analogue instruments the historical concept of analogue solutions was abandoned and an analytical plotter, based on computations was developed at the National Research Council (Ottawa). In this instrument the basic inputs are known constants and coordinates of points corresponding in stereo photographs, observed and measured in the instrument. This represented a real breakthrough in photogrammetric technique and marks a new era in further development in the field. Only a few characteristics will be mentioned: use of any images as long as they are geometrically well defined (arbitrary geometric characteristic of cameras), basic operations based on the judgment of an operator are replaced by mathematical computations (partial automation), time of these operations drastically reduced, errorless transfer of parameters, enormous simplification of instruments, unlimited possibility in introducing corrections including corrections for constant instrumental errors, choice of reference surface, type of projection, etc. SCIENTIFIC INSTRUMENT COMMISSION o/nu IUHPS 1.4 LA COMMISSION DES INSTRUMENTS SCIENTIFIQUES ifaUIHPS Title / Titre Surveying in the Cold War Author / Auteure Deborah Jean Warner Affiliation / Affiliation National Museum of American History, Smithsonian Institution Address / Adresse 5128 NMAH, Smithsonian Institution Washington, DC, 20560 USA Abstract / Resume As World War II came to an end, many people became aware that only a small portion of the Earth's landmass had been surveyed with the accuracy needed for economic development, military preparedness, and scientific understanding. The need to know the exact size and shape of the Earth increased with the introduction of intercontinental missiles, artificial satellites, and planned flights to the Moon in the 1960s. Americans responded to this need in many ways, and with massive amounts of funding. The U.S. Coast & Geodetic Survey initiated a first-order transcontinental traverse of the United States, agencies in the various states sponsored the control surveys needed for the Interstate Highway Act of 1956, and the U. S. Army Engineers and the Army Map Service conducted and/or sponsored third-order surveys of many remote areas of the globe. At the same time that government leaders were facing this rising demand for ever more precise surveys, even in areas where the terrain was rough or the temperatures extreme, scientists and engineers (often with the help of public funds) were revolutionizing instruments used to accomplish these tasks. One important set of the new ground-based instruments were those which measured distances electronically (that is, with visible light, microwaves, lasers, or infrared radiation). I will discuss these EDMs as both products and tools of the Cold War, suggesting ways in which the technologies were related to other products of the military-industrial complex, and indicating some of the new tasks to which they were applied. SCIENTIFIC INSTRUMENT COMMISSION »/*« IUHPS 2.1 LA COMMISSION DES INSTRUMENTS SCIENTIFIQUES ifeUIHPS Title/ Titre 'Spirit of Place': geographical implications of the English provincial instrument trade, 1760-1850 Author / Auteure Alison Morrison-Low Affiliation / Affiliation National Museums of Scotland and the University of York Address / Mresse Chambers Street Edinburgh EH 1 1JF Scotland Abstract / Resume Although London remained the largest

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