## mega- Quick reference

### A Dictionary of Weights, Measures, and Units

...[Gk: ‘great’] Symbol M-. Metric The 10 6 multiplier, e.g. 1 megajoule = 1 MJ = 10 6 J; contractable to meg- before a vowel, e.g. 1 megohm = 1 MΩ = 10 6 Ω. informatics . Sometimes 1 048 576 = 2 20 , but see mebi- then kibi-...

## poise Quick reference

### A Dictionary of Weights, Measures, and Units

...[ J. L. M. Poiseuille ; France 1799–1869 ] dynamic viscosity . Symbol P. Metric-c.g.s. Identically dyne⋅second per square centimetre (dyn⋅s⋅cm -2 ) = 10 -1 N⋅s⋅m -2 = 10 -1 Pa⋅s(= cm -1 ⋅g⋅s -1 in c.g.s. base terms). Hence • P⋅(g⋅cm -3 ) -1 = stokes for kinematic viscosity. The poise is a large unit for most purposes, water at 20°C having a viscosity of 10.020∼ mP and most free-flowing liquids typically being similar; gases are around 1 μP. There is no equivalent special term in the...

## gallon Quick reference

### A Dictionary of Weights, Measures, and Units

...L (0.832 674 2∼ BI gal). See Table 17(b). US-C dry There is no gallon for dry goods; see bushel . Table 17(a) BI, Australia, Canada, New Zealand, etc., SI US-C liq fl oz … … … … … 28.4∼ mL 0.961∼ oz 5 gill … … … … 142∼ mL 4.80∼ oz 20 4 pint … … … 568∼ mL 1.20∼ pt 40 8 2 quart … … 1.14∼ L 1.20∼ qt 160 32 8 4 gallon … 4.55∼ L 1.20∼ gal 2 peck 9.09∼ L 2.40∼ gal 8 4 bushel 36.4∼ L 9.61∼ gal For downward extension, see fluid ounce . Table 17(b) US-C for liquids SI liq oz … … … … … 29.6∼ mL 4 gill … … … … 118.∼ mL 16 4 pint … … … 473.∼ mL 32 8 2 quart … … 946.∼...

## apothecaries' scale Quick reference

### A Dictionary of Weights, Measures, and Units

...the UK, e.g. oz ap. Unlike the more usual avoirdupois scale with its pound of 16 ounces and 7 000 grains (making its ounce 437.5 gr), the apothecaries' scale, like the troy scale , has a pound of only 12 ounces each of 480 grains, giving a total of 5 760 grains, the grain being the one unit common to all three scales. The distinctive scale for apothecaries' units is shown in Table 2. Table 2 BI-apoth, US-C-ap Internat values: SI US-C-av grain … … … 64.8∼ μg 1 gr 20 scruple … … 1.30∼ g 20 gr 60 3 drachm, dram … 3.89∼ g 60 gr 480 24 8 ounce 31.1∼ g 1.10∼ oz...

## poiseuille Quick reference

### A Dictionary of Weights, Measures, and Units

...metre or kilogram per metre⋅second, = N⋅s⋅m -2 = Pa⋅s; there is no use of it else any equivalent term in the SI (= m -1 ⋅kg⋅s -1 in m.k.s. base terms). It has rarely been used outside of France. Even more than its predecessor, the poise of c.g.s., the poiseuille is a large unit for most purposes, water at 20°C having a viscosity of 1.002 0∼ mPl and most free-flowing liquids typically being similar, with gases being below 1...

## windchill (factor) Quick reference

### A Dictionary of Weights, Measures, and Units

...to reflect the greater freezing effect, particularly on hairless human skin and flesh, of low temperatures when accompanied by significant wind. The initial form consisted merely of subtracting the Fahrenheit temperature from the wind speed measured in miles per hour, e.g. a wind of 20 m.p.h. and a temperature of -30°F gave a windchill of 50, equatable with -50°F in calm conditions. The real effect is far from linearly additive in such a simple (and convenient) manner. Careful study has produced more complex formulations, convertible to a rate of heat loss...

## pound Quick reference

### A Dictionary of Weights, Measures, and Units

...g, so 1 kg = 2.204 622 62∼ lb. Bigg P. H. Nature 194, 719–21 (1962) Canada 1951 453.592 43 g, so 1 kg = 2.204 622 33∼ lb.Canada: An Act respecting Weights and Measures assented to 20 June 1951 BI 1898 By Order-in-Council it was declared that, on the basis of comparative measurement of the prototype pound and the international prototype kilogram, 1 kg = 2.204 622 3 lb, so 1 lb = 453.592 436∼ g (making the prototype pound obsolescent, but not displacing it). US-C 1893 Defined by the Mendenhall Order , = 1 / 2.20462234 kg = 1 / 453.5924277 ∼ g,...

## binary Quick reference

### A Dictionary of Weights, Measures, and Units

...Relating to anything having just two alternatives, or based on such (see below), in contrast with the steps of 10 and its powers for decimal and its compounds, of 12 for duodecimal , 16 for hexadecimal , 20 for vigesimal , 60 for sexagesimal , etc. In both the material and the electrical worlds, from the presence or absence of an item (e.g. a hole in a card, the on/off of electricity) to the north/south polarity of magnetism, the binary state is of widespread natural significance. Hence, although efforts to mimic decimal notation have been made, the...

## preferred numbers Quick reference

### A Dictionary of Weights, Measures, and Units

...R10″, precise sub-sets of the denser set for the same level of rounding, specifically every second and every fourth, starting at 10. Any such methodical subset can be used, e.g. R20′/3 (10‥40) for every third value of R20′ running from 10 to 40, i.e. the values 10, 14, 20, 28, 40. The USA has an equivalent standard used worldwide for electronic components, but with the number of steps binary multiples of 6 rather than of 5, ranging up to 192 steps. (It has also had a standard using fractions of an inch. Van Dyck A. Proc. Inst. Radio Engrs 24, 159–79...

## hundredweight Quick reference

### A Dictionary of Weights, Measures, and Units

...hundredweight ) in North America. See pound for more precise values, and Table 25 for scales. Table 25(a) BI, Australia, New Zealand SI lb … … … … 454.∼ g 14 stone … … … 6.35∼ kg 28 2 quarter … … 12.7∼ kg 112 8 4 hundredweight … 50.8∼ kg 2 240 20 ton 1016.∼ kg For downward extension, see ounce . Table 25(b) US-C, Canada SI lb … … … … 454.∼ g 25 quarter … … 11.3∼ kg 100 4 hundredweight … 45.4∼ kg 2 000 20 ton 907.∼ kg For downward extension, see ounce . The cwt was removed from official UK measures in 1985 .The UK Weights and Measures Act 1985 ...

## calorie Quick reference

### A Dictionary of Weights, Measures, and Units

...for any precise use, since the amount is dependent on starting temperature. This is denoted by a suffix, e.g. cal 15 denotes the rise from 14.5 to 15.5°C; cal mean denotes the mean per degree over the range 0 to 100°C. international steam calorie cal IT = 4.186 74∼ J, mean calorie cal mean = 4.190 02∼ J 4°C calorie cal 4 = 4.204 5∼ J (water at its densest) 15°C calorie cal 15 = 4.185 5∼ J (15°C = cool indoors) 20°C calorie cal 20 = 4.181 90∼ J (20°C = warm indoors) The cal 15 is usually meant by the mechanical equivalent of heat . The international steam...

## normalized Quick reference

### A Dictionary of Weights, Measures, and Units

...mathematics . Applied to numbers expressed as a mantissa multiplied by an exponential expression, e.g. 8.97∼ × 10 20 , the term applies to having the mantissa within some defined range. The above is identically 0.897∼ × 10 21 , 89.7∼ × 10 19 , 897.∼ × 10 18 , 0.089 7∼ × 10 22 , and any other of the unlimited equivalent variants. Clearly any non-zero number can be written such that the mantissa is within some pre-set range that spans, multiplicatively, the size of the base. For base 10, as in the above example, we can fix the range to be from 1...

## pitch Quick reference

### A Dictionary of Weights, Measures, and Units

... f 293.665∼ D 1.189 2∼ f 311.127∼ • (5 f /4 = 1.250 0 f ) 1.259 9∼ f 329.628∼ E (4 f /3 = 1.333 3∼ f ) 1.334 8∼ f 349.228∼ F 1.414 2∼ f 369.994∼ • (3 f /2 = 1.500 0 f ) 1.498 3∼ f 391.995∼ G 1.587 4∼ f 415.305∼ • (5 f /3 = 1.666 7∼ f ) 1.661 8∼ f 440. A 1.781 8∼ f 446.164∼ • (15 f /8 = 1.875 0 f ) 1.887 7∼ f 493.883∼ B (2 f /1 = 2 f ) 2.0 f 523.251∼...

## quantile Quick reference

### A Dictionary of Weights, Measures, and Units

...ten else 100, graduating conventionally from the smallest values of the statistic to the largest. Thus a member in the third quartile is larger than at least half the members and smaller than at least a quarter of the members; a member in the third decile is larger than at least 20% of the members and smaller than at least 70% of the members; a member in the third percentile is larger than at least 2% of the members and smaller than at least 97% of the members. The demarcation between the second and third quartile, the fifth and sixth decile and the 50th and...

## kilogram Quick reference

### A Dictionary of Weights, Measures, and Units

...of metre and other base, supplementary, and derived units. In such a context it is quite appropriate to indicate 1 gram as 10 -3 kg, 1 milligram as 10 -6 kg and so on. (But note that the use of powers that are not multiples of 3 is deprecated under the SI; 20 g can be written as 20 × 10 -3 kg, but is not acceptable as 2 × 10 -2 kg.) History The kilogram began, with the name grave , as merely the 1 000 multiple of the gram, that unit being originally defined as the mass of 1 cm 3 of pure water at its maximal volumic mass. However, the kilogram...

## equation of time Quick reference

### A Dictionary of Weights, Measures, and Units

...+1m32s -3m38s -51s 10 11 +7m38s +14m19s +10m18s +1m16s -3m40s -39s 11 12 +8m02s +14m20s +10m02s +1m00s -3m42s -27s 12 13 +8m25s +14m19s +9m46s +44s -3m44s -15s 13 14 +8m48s +14m18s +9m30s +29s -3m44s -3s 14 15 +9m10s +14m16s +9m13s +14s -3m44s +10s 15 16 +9m32s +14m13s +8m56s -01s -3m44s +23s 16 17 +9m52s +14m10s +8m39s -15s -3m43s +36s 17 18 +10m12s +14m06s +8m22s -29s -3m41s +49s 18 19 +10m32s +14m01s +8m04s -43s -3m39s +1m02s 19 20 +10m50s +13m55s +7m46s -56s -3m37s +1m15s 20 21 +11m08s +13m49s +7m28s -1m09s -3m34s +1m28s 21 22 +11m25s +13m42s +7m10s -1m21s...

## decibel Quick reference

### A Dictionary of Weights, Measures, and Units

...distinguishing label dBA but often just as dB, the reference is usually the threshold of human audibility, taken as sound of an amplitude (pressure) of 20 μPa and a frequency of 1 kHz. Sound sufficient to cause pain is of the order of 10 12 times as strong as the threshold, i.e. increased by 120 dB (to 120 dBA); http://www.npl.co.uk/npl/publications/acoustics/ chronic exposure to anything over 85 dBA (e.g. near non-sound-deadened pneumatic drills or within 1 000 m of a jet aircraft) can cause permanent hearing damage. If either low or high frequencies are...

## calendar Quick reference

### A Dictionary of Weights, Measures, and Units

...adjustment, proposed but yet to apply, and potentially to be varied because of the minutely changing length of the average day and average year, is to exclude from being leap years those years that are multiples of 4 000. This would leave the year overstated by about one day per 20 000 years. The occurrence of the northern spring equinox on or about 21 March is thus a deliberate feature of the Gregorian calendar, harking back to the Julian, but the original cause of any such arrangement is unclear. Since the tropical year equals 365.242 2∼ days, equal...

## in. Quick reference

### A Dictionary of Weights, Measures, and Units

...times was technically different in each of the UK, the USA, and Canada prior to the agreed international standard, Nature 183, 80–1 (1959) though mutual differences were less than 0.001%. Introduced in Canada in 1951 Canada: An Act respecting Weights and Measures assented to 20 June 1951 then in the UK, the USA, Australia, and New Zealand in 1959 (though in the UK not completely until 1964 ), the international value has the inch an integer multiple of a tenth of the millimetre, hence the foot, yard, etc., likewise. However, through a succession of ...

## particle size Quick reference

### A Dictionary of Weights, Measures, and Units

...1 and 10 / 3 to achieve an overall decimal progression.) Table 38 US sieve USDA U-W ϕ mm International British boulder boulder -12 4 096 cobble boulder -11 2 048 -10 1 024 -9 512 cobble -8 256 cobble 254 203.2 cobble -7 128 gravel 76.2 pebble -6 64 60 coarse pebble gravel -5 32 20 medium pebble -4 16 -3 8 6 fine pebble granule -2 4 10 very coarse sand very coarse sand -1 2 coarse sand coarse sand 18 coarse sand coarse sand 0 1 0.6 medium sand 35 medium sand medium sand 1 0.5 60 fine sand fine sand 2 0.25 0.2 medium sand fine sand very fine sand 3 0.125 140...