Volume 1

Jugoslavia / by Alice Garnett [and others].

  • Great Britain. Naval Intelligence Division.
Date:
1944-1945
Catalogue details

Licence: Public Domain Mark

Credit: Jugoslavia / by Alice Garnett [and others]. Source: Wellcome Collection.

    420/444 (page 320)
    CONVERSION TABLES METRIC AND BRITISH UNITS It is customary to think of the ‘ metre’ and the ‘ yard ’ as representing unalterable units of length. This is not so. The metre was originally intended to be the 10,000,000th part of the earth’s meridional quadrant. But the accurate determina- tion of this length proved to be extremely difficult—partly for technical reasons, and partly because of different conceptions of the ‘ figure of the earth ’. In view of these difficulties it became necessary to define the length of the metre in terms of suitable metal bars measured under specified conditions of temperature, pressure, humidity, etc. Similar standard bars were also used to define the length of other units such as the yard. As all these metallic standards are subject to change, conversion tables differ according to the date of comparison between different bars. The tables that follow are based on the comparison between the yard and the metre made in 1895. This made 1 metre equivalent to 39°370113 in. Metric System: List of Prefixes Deca means ten times. Deci means a tenth part of. Hecto means a hundred times. Centi means a hundredth part of. Kilo means a thousand times. Milli means a thousandth part of. In abbreviations the Decametre, etc., is Dm., and the decimetre, etc., dm. Note on ‘ Nautical’, ‘ Geographical’ and ‘ Statute’ miles A British ‘ nautical mile ’ is the length of the minute of the meridian at any given latitude, and is therefore a variable unit. It is given in feet for Clarke’s 1880 spheroid by the formula 60771°I — 30°7 cos 2 Lat. This is the sea mile of the scale of latitude and distance of the Admiralty Charts. From the above formula it will be found to vary from 6,046-4 ft. at the equator to 6,107°8 ft. at the poles, being 6,077°1 ft. at latitude 45°. The so-called ‘ international nautical mile’ of 1,852 m. or 6,076 ft. is the length of the minute of the meridian at latitude 45° on the international spheroid. This corresponds to the 6,077 ft. for Clarke’s spheroid. A ‘ geographical mile’ is a fixed unit, being defined by some as the length of a minute of the equator and by others as that of the minute of the meridian at latitude 45°. According to the former definition its value on Clarke’s spheroid is 6,087 ft. and according to the latter 6,077 ft. The round figure 6,080 is usualy adopted for the purposes of ordinary navigation. The British ‘ statute mile ’ measures 5,280 ft. List OF CONVERSION ‘TABLES PAGE 1. Length : ‘ : : 4 ‘ : : “ ‘ ‘ . 2a 2. Area . $ : : , f : j ‘ : . a 3. Yield per ke Vives P ; : ; ; : ; : : . saa 4. Volume and Capacity . ’ : ‘ . ; : : ; - sae 5. Weight . é ; : , : ; ‘ z ‘ : . 2a 6. ‘Temperature : Equivalents of Fahrenheit and Centigrade Scales . . sa 7. Pressure : Equivalents of Millibars, Millimetres of Mercury, and Inches of Mercury at 32° F. in Latitude ans 3 : : 324 329