Online Encyclopedia


Online Encyclopedia
Originally appearing in Volume V25, Page 240 of the 1911 Encyclopedia Britannica.
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SLEEPER, a term used with many technical applications for a piece of timber, metal, &c., used as a support; in carpentry it is such a piece of timber laid on low cross walls as a plate to receive ground joists; in shipbuilding, a strengthening timber for the bows and stern frame; the most frequent use of the term is for a timber or steel support on which the chairs are fixed for carrying the rails on a railway; in America these are called" ties " (see RAILWAYS). The common explanation of the origin of the word is to connect it with " sleep," the timbers supposed to be lying at rest. The real source of the word is the Norv,egian sleip, a piece of timber used for dragging things over, a roller, especially used of timbers laid in a row in making a road. This word Skeat (Etymol. Diet., 1898) connects with " slab," a flat piece of stone or wood. The French term dormant is used in carpentry, but as part of the frame of a window or door. SLEEPING-SICKNESS (Trypanosomiasis), a remarkable parasitic disease, familiar among West African natives since the beginning of the 19th century, and characterized by protracted lethargy, fever and wasting. It is attributed to the trypanosoma gambiense, a parasite which was discovered in the frog by Gruby in 1847, and in 188o by Griffith Evans in horses afflicted with the disease called " surra " in India. In 1895 Surgeon-Major (afterwards Sir) D. Bruce found a trypanosoma similar to Evans's in cases of what was known in cattle as " tsetse-fly disease "; and though the trypanosoma had not then actually been found in man, Bruce suggested that this was akin to the human " sleeping-sickness " which had now extended into the Congo Free State, Uganda and elsewhere, and was causing great mortality, many Europeans having died of the disease. In 1903 Castelani found the trypanosoma in the cerebra-spinal fluid of human patients afflicted with the disease. The question of the pathology of " sleeping-sickness " was vigorously taken up, and in June 1907 an international conference was held in London for the purpose of organizing research on the subject. As was pointed out by Lord Fitzmaurice (18th of June), in his opening address, it was already accepted that trypanosoma gambiense was the cause of the disease, and it was even then " all but proved " that the parasite was conveyed by at least one species of tsetse fly (glossina palpalis), the distribution of which was limited to the neighbourhood of open water. It had further been ascertained, experimentally in animals, and therapeutically in man, that the infection once acquired could be controlled, to some extent, by various substances—arsenic, certain colours, dyes, in combinations of arsenic and colour dyes, e.g. atoxyland by mercury. It remained a question how far certain unascertained factors were at work in the spread of the disease, and for this purpose the British government invited the co-operation of all the powers interested in tropical Africa in considering certain problems, annual or biennial conferences being suggested, and the formation of a central bureau, in order to organize the research. These problems were: (I) to determine whether the tsetse fly (glossina palpalis) was a direct or indirect conveyor of the parasite; (2) whether the parasite underwent necessary developmental changes in the tsetse fly; (3) if so, whether the developed germs were conveyed by the original fly or its larva when arrived at the imago stage; (4) how long an infected glossina palpalis remained infected; (5) whether other species of glossina were concerned; (6) the geographical distribution and habits of the fly; (7) whether and how far the spread of infection was the work of any of the vertebrate fauna (other than man); (8) to suggest preventive methods for exterminating the glossina, or protecting uninfected districts by segregation or otherwise; (9) to study the therapeutics of the disease. In the history of modern pathology, this organization of research in respect of " sleeping-sickness " must hold an important place as the application of state effort on behalf of the advancement of science. (See NEUROPATHOLOGY and PARASITIC DISEASES.)
End of Article: SLEEPER
SLEEP (0. Eng. slcepan; Ger. schlafen; cf. Lat. lab...
SLEET (either from Nor. sletta, of the same meaning...

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