The aphemetric compass : an instrument for measuring the degree of discriminative power, as regards contactile impressions, enjoyed by the skin and mucous membranes in certain affections of the nervous system / by John W. Ogle, M.D.

  • John Ogle
Date:
[1859]
Catalogue details

Licence: Public Domain Mark

Credit: The aphemetric compass : an instrument for measuring the degree of discriminative power, as regards contactile impressions, enjoyed by the skin and mucous membranes in certain affections of the nervous system / by John W. Ogle, M.D. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    from each other, whilst at the same time the distances between them are simultaneously and clearly indicated (a process which greatly aids rapid observation) is preeminently convenient. Again, its value is enhanced by the fact that it may be used much more freely than the instruments (formed of a straight piece of metal) already spoken of for measuring contactile dis- criminative power, in the measurement about the joints, or wrists, or feet, where an irregularity or considerable convexity of the surface obtains. I must allow that, as regards its application, this instrument which I have had made docs not quite possess sufficient range of measuring power, as it is not quite able to measure five inches of the surface; but of course this defect is easily remedied in future instruments of the kind.* In conclusion, I cannot help saying, that although the appli- cation of Professor Weber's physiological discovery to clinical and pathological purposes is most admii'able and interesting, yet it has not been found by me to be so very extensively practical as might have been supposed. I have made use of it as a means of diagnosis in very many instances, which I need not now detail, and in numerous cases, owing to the peculiar mental condition attendant upon the cause of the sensory paralysis which was under investigation, I have found that the perceptions and the statements of the patient could not be at all considered trust- worthy. The complication of intellectual weakness with the pathological interference as regards sensory and motor paralysis, and the natural obtuseness when in health, and want of habit, in attending precisely to any sensations whatever, or in explain- ing any sensations of which the mind may be cognisant, (met with so often, especially among hospital patients,) have not infre- quently rendered this mode of diagnosis and prognosis by means of the aphemetrical compass perfectly nugatory. Add to this * I have given to this instrument the name aphemetric compass, rather than the neater and more euphonious one of scsthe.-^iometer, inasmuch as I was desirous that its designation should be one carrying its own meaning with it as much as possible. The word rcsthesiometer would of course apply to an instrument intended to measure the degree of any kind of sensation whatever, whereas the title aphemetric cnmpass only has reference to the sense of contact, and in a more accurate Avay than aBsthesiometer indicates the use and application of this instrument. This instrument obtains favour also, I was glad to find, with others than phy- siologists and physicians. One skilled in mechanics and mathematical appliances spoke in a highlj' favourable way of its future use for quickly and accuratelj'reduc- ing geometrical distances in the construction of plans, engineering diagrams, &c.; and of its serving, in a superior manner, the purpose of the calipers in ordinary use. Perhaps, if the limbs of the compass were somewhat arched, this intention of geometrical mensuration would, by making it useful in the case of solid bodies, &c., render it still more generally available.
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