Volume 1

Methods of practical hygiene / translated by W. Crookes.

  • Karl Bernhard Lehmann
Date:
1893
Catalogue details

Licence: Public Domain Mark

Credit: Methods of practical hygiene / translated by W. Crookes. Source: Wellcome Collection.

    76/468 page 48
    r 7t s, where s is the shortest distance from the base and the vertex, measured on the mantle of the cone, and r is the radius of the base. The superficies of a sphere = 4 r2 ir. § 36. Determination of Cubic Space.—The contents of the regular bodies which are met with in hygienic operations may be simply measured if we know the length of their sides. Cube = s3. Prism (three-, four- [parallelopipedon], or many-sided, or with a round surface [cylinder]) always = g h, where g is the surface of the base and h is the height. If the prism is oblique, h is put for the vertical distance of the two parallel surfaces. Pyramids and Cones = ^0-, in which g is the surface of the L o base, h the perpendicular distance of the apex above it. Sphere = £ rz it. In all these cases it is indispensable that all the measures of length shall be expressed in one and the same scale—that is, all in metres, decimetres, centimetres, or millimetres. The result is then expressed correspondingly in square metres, square decimetres, square millimetres, or, as the case may be, in cubic metres, cubic centimetres, &c. Bub if one magnitude is, for instance, measured in centi- metres and the other in millimetres, on multiplying them an irrational result is obtained—a frequent error with beginners. § 37. The cubic contents of an irregular body (e.g., a boulder or a beet-root) is calculated by weighing it, and dividing the number thus obtained by the specific gravity, i.e., the weight of 1 cc. of the substance. But the specific gravity is mostly not sufficiently known, and to ascertain it its volume must be determined. The volume of a body is found by suspending it from a fine wire, and allowing it to be immersed in a glass of water previously tared and set upon the pan of a balance. The increase of weight of the glass of water in grammes expresses
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