Roman Numerals

The primary symbols are I 1, V 5, X 10, L 50, C 100, D 500, M 1,000. If a lesser symbol is placed to the right of a greater, its value is added to that of the greater; if it placed to the left, its value is subtracted. Small subtractions from large values are avoided (e.g. 99 is XCIX not IC). Roman numerals may appear in lower case (i, v, x, l, c, d, m), but the practice of printing e.g. viij for viii is now archaic. The sequences IIII, XXXX, and CCCC are occasionally used instead of the usual forms (for example, on old clock faces).

1 I

2 II

3 III

4 IV

5 V

6 VI

7 VII

8 VIII

9 IX

10 X

11 XI

12 XII

13 XIII

14 XIV

15 XV

16 XVI

17 XVII

18 XVIII

19 XIX

20 XX

21 XXI

30 XXX

40 XL

49 XLIX

50 L

60 LX

70 LXX

80 LXXX

90 XC

99 XCIX

100 C

101 CI

144 CXLIV

200 CC

400 CD (or CCCC)

500 D

900 CM (or DCCCC)

1000 M

1900 MCM (or MDCCCC)

1995 MCMXCV

1999 MCMXCIX

2000 MM

 

 

Weights, Measures, and Units

Conversion factors are not exact unless so marked.

1. British and American, with Metric Equivalents

Linear Measure

1 inch = 25.4 millimetres exactly

1 foot = 12 inches = 0.3048 metre exactly

1 yard = 3 feet = 0.9144 metre exactly

1 (statute) mile = 1.609 kilometres

= 1,760 yards

1 int. nautical mile = 1.852 kilometres exactly

= 1.150779 miles

Square Measure

1 square inch = 6.45 sq. centimetres

1 square foot = 9.29 sq. decimetres

= 144 sq. in.

1 square yard = 0.836 sq. metre

= 9 sq. ft

1 acre = 4,840 sq. yd = 0.405 hectare

1 square mile = 259 hectares

= 640 acres

Cubic Measure

1 cubic inch = 16.4 cu. centimetres

1 cubic foot = 0.0283 cu. metre

= 1,728 cu. in.

1 cubic yard = 27 cu. ft = 0.765 cu. metre

Capacity Measure

British

1 fluid oz = 0.0284 litre

= 1.8047 cu. in.

1 gill = 5 fluid oz = 0.1421 litre

1 pint = 20 fluid oz = 0.568 litre

= 34.68 cu. in.

1 quart = 2 pints = 1.136 litres

1 gallon = 4 quarts = 4.546 litres

1 peck = 2 gallons = 9.092 litres

1 bushel = 4 pecks = 36.4 litres

American dry

1 pint = 33.60 cu. in. = 0.550 litre

1 quart = 2 pints = 1.101 litres

1 peck = 8 quarts = 8.81 litres

1 bushel = 4 pecks = 35.3 litres

American liquid

1 pint = 16 fluid oz = 0.473 litre

= 28.88 cu. in.

1 quart = 2 pints = 0.946 litre

1 gallon = 4 quarts = 3.785 litres

Avoirdupois Weight

1 grain = 0.065 gram

1 dram = 1.772 grams

1 ounce = 16 drams = 28.35 grams

1 pound = 16 ounces = 0.4536 kilogram (0.45359237 exactly)

= 7,000 grains

1 stone = 14 pounds = 6.35 kilograms

1 hundredweight = 50.80 kilograms

= 112 pounds

1 short ton = 0.907 tonne

= 2,000 pounds

1 (long) ton = 1.016 tonnes

= 20 hundredweight

2. Metric, with British Equivalents

Linear Measure

1 millimetre = 0.039 inch

1 centimetre = 10 mm = 0.394 inch

1 decimetre = 10 cm = 3.94 inches

1 metre = 100 cm = 1.094 yards

1 kilometre = 1,000 m = 0.6214 mile

Square Measure

1 square centimetre = 0.155 sq. inch

1 square metre = 1.196 sq. yards

= 10,000 sq. cm

1 are = 119.6 sq. yards

= 100 square metres

1 hectare = 100 ares = 2.471 acres

1 square kilometre = 0.386 sq. mile

= 100 hectares

Cubic Measure

1 cubic centimetre = 0.061 cu. inch

1 cubic metre = 1.308 cu. yards

= 1,000,000 cu. cm

Capacity Measure

1 millilitre = 0.002 pint (British)

1 centilitre = 10 ml = 0.018 pint

1 decilitre = 10 cl = 0.176 pint

1 litre = 1000 ml = 1.76 pints

1 decalitre = 10 l = 2.20 gallons

1 hectolitre = 100 l = 2.75 bushels

1 kilolitre = 1,000 l = 3.44 quarters

Weight

1 milligram = 0.015 grain

1 centigram = 10 mg = 0.154 grain

1 decigram = 100 mg = 1.543 grains

1 gram = 1000 mg = 15.43 grains

1 decagram = 10 g = 5.64 drams

1 hectogram = 100 g = 3.527 ounces

1 kilogram = 1,000 g = 2.205 pounds

1 tonne (metric ton) = 0.984 (long) ton

= 1,000 kg

 

3. Temperature

Fahrenheit: water boils (under standard conditions) at 212° and freezes at 32°.

Celsius or Centigrade: water boils at 100° and freezes at 0°.

Kelvin: water boils at 373.15 K and freezes at 273.15 K.

To convert Centigrade into Fahrenheit: multiply by 9, divide by 5, and add 32.

To convert Fahrenheit into Centigrade: subtract 32, multiply by 5, and divide by 9.

To convert Centigrade into Kelvin: add 273.15.

°F °C °C °F

(approx.) (exact.)

-40 -40 -40 -40

-10 -23 -10 -14

0 -18 0 32

10 -12 10 50

20 -7 20 68

30 -1 30 86

40 4 40 104

50 10 50 122

60 16 60 140

70 21 70 158

80 27 80 176

90 32 90 194

100 38 100 212

4. Power Notation

This expresses concisely any power of 10 (any number that is formed by multiplying or dividing ten by itself), and is sometimes used in the dictionary.

102 (ten squared) = 10 × 10 = 100

103 (ten cubed) = 10 × 10 × 10 = 1,000

104 = 10 × 10 × 10 × 10 = 10,000

1010 = 10,000,000,000 (1 followed by ten noughts)

10-2 = 1/102 = 1/100 = 0.01

10-10 = 1/1010 = 1/10,000,000,000

6.2 × 103 = 6,200

4.7 × 10-2 = 0.047

 

5. The Metric Prefixes

Abbreviations Factors

deca- da 10

hecto- h 102

kilo- k 103

mega- M 106

giga- G 109

tera- T 1012

peta- P 1015

exa- E 1018

deci- d 10-1

centi- c 10-2

milli- m 10-3

micro- m 10-6

nano- n 10-9

pico- p 10-12

femto- f 10-15

atto- a 10-18

 

6. SI Units

Base units

Physical quantity Name Abbreviation

or symbol

length metre m

mass kilogram kg

time second s

electric current ampere A

temperature kelvin K

amount of substance mole mol

luminous intensity candela cd

Supplementary units

Physical quantity Name Abbreviation

or symbol

plane angle radian rad

solid angle steradian sr

Derived units with special names

Physical quantity Name Abbreviation

or symbol

frequency hertz Hz

energy joule J

force newton N

power watt W

pressure pascal Pa

electric charge coulomb C

electromotive force volt V

electric resistance ohm O

electric conductance siemens S

electric capacitance farad F

magnetic flux weber Wb

inductance henry H

magnetic flux density tesla T

luminous flux lumen lm

illumination lux lx

 

7. Binary Notation

Only two digits (0 and 1) are used, and the position of each digit in a number indicates a power of two. For example, two is written as 10 (2 + 0), five as 101 (22 + 0 + 1), ten as 1010 (23 + 0 + 2 + 0 = 8 + 2), and one hundred as 1100100 (26 + 25 + 0 + 0 + 22 + 0 + 0 = 64 + 32 + 4).

1 1

10 2

11 3

100 4

101 5

110 6

111 7

1000 8

1001 9

1010 10

1011 11

1100 12

1101 13

1110 14

1111 15

10000 16

10001 17

10010 18

10011 19

10100 20

10101 21

10110 22

10111 23

11000 24

11001 25

11010 26

11011 27

11100 28

11101 29

11110 30

11111 31

100000 32

 

 

The Chemical Elements

(in order of atomic number)

hydrogen H 1

helium He 2

lithium Li 3

beryllium Be 4

boron B 5

carbon C 6

nitrogen N 7

oxygen O 8

fluorine F 9

neon Ne 10

sodium Na 11

magnesium Mg 12

aluminium Al 13

silicon Si 14

phosphorus P 15

sulphur S 16

chlorine Cl 17

argon Ar 18

potassium K 19

calcium Ca 20

scandium Sc 21

titanium Ti 22

vanadium V 23

chromium Cr 24

manganese Mn 25

iron Fe 26

cobalt Co 27

nickel Ni 28

copper Cu 29

zinc Zn 30

gallium Ga 31

germanium Ge 32

arsenic As 33

selenium Se 34

bromine Br 35

krypton Kr 36

rubidium Rb 37

strontium Sr 38

yttrium Y 39

zirconium Zr 40

niobium Nb 41

molybdenum Mo 42

technetium Tc 43

ruthenium Ru 44

rhodium Rh 45

palladium Pd 46

silver Ag 47

cadmium Cd 48

indium In 49

tin Sn 50

antimony Sb 51

tellurium Te 52

iodine I 53

xenon Xe 54

caesium Cs 55

barium Ba 56

lanthanum La 57

cerium Ce 58

praseodymium Pr 59

neodymium Nd 60

promethium Pm 61

samarium Sm 62

europium Eu 63

gadolinium Gd 64

terbium Tb 65

dysprosium Dy 66

holmium Ho 67

erbium Er 68

thulium Tm 69

ytterbium Yb 70

lutetium Lu 71

hafnium Hf 72

tantalum Ta 73

tungsten W 74

rhenium Re 75

osmium Os 76

iridium Ir 77

platinum Pt 78

gold Au 79

mercury Hg 80

thallium Tl 81

lead Pb 82

bismuth Bi 83

polonium Po 84

astatine At 85

radon Rn 86

francium Fr 87

radium Ra 88

actinium Ac 89

thorium Th 90

protactinium Pa 91

uranium U 92

neptunium Np 93

plutonium Pu 94

americium Am 95

curium Cm 96

berkelium Bk 97

californium Cf 98

einsteinium Es 99

fermium Fm 100

mendelevium Md 101

nobelium No 102

lawrencium Lr 103

All these elements and their symbols are listed alphabetically in the main part of the dictionary.

All the elements heavier than bismuth (no. 83) are radioactive; all those heavier than uranium (no. 92) have only been produced artificially. The names given above for elements up to 103 are in standard use. Names for elements 104 and above are not yet standardized and have been the subject of controversy:

provisional name suggested names

104 unnilquadium kurchatovium, rutherfordium, (dubnium)

105 unnilpentium hahnium, nielsbohrium, (joliotium)

106 unnilhexium seaborgium, (rutherfordium)

107 unnilseptium (bohrium)

108 unniloctium (hahnium)

109 ? (meitnerium)

The IUPAC provisional names are based on the atomic number and are formed from the numerical roots nil = 0, un = 1, bi = 2, etc. The bracketed names are under consideration by IUPAC; the others have been in informal use.

Chemical Notation

The formula for a compound indicates the number of atoms of each element present in each molecule of the compound: e.g. a molecule of water (H2O) contains two atoms of hydrogen and one of oxygen. The formula for an ionic compound indicates the proportions of the constituent elements, e.g. common salt (NaCl) contains equal proportions of sodium and chloride ions. Formulae for more complex compounds may indicate the manner of combination of the atoms in a molecule: e.g. ethanol (ethyl alcohol) may be represented as CH3CH2OH.

PERIODIC TABLE OF CHEMICAL ELEMENTS

IA IIA IIIB IVB VB VIB VIIB - VIII - IB IIB IIIA IVA VA VIA VIIA 0

(H) He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

Cs Ba La1 Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

Fr Ra Ac2 Unq Unp Unh Uns Uno

1Lanthanides La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

2Actinides Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

Major Divisions of Geological Time

Era Period Epoch Duration

Quaternary Holocene 100,000 bp to present

Pleistocene 2 mya-100,000 bp

Cenozoic Tertiary Pliocene 5-2 mya

Miocene 24-5 mya

Oligocene 38-24 mya

Eocene 55-38 mya

Palaeocene 65-55 mya

Cretaceous 144-65 mya

Mesozoic Jurassic 213-144 mya

Triassic 248-213 mya

Permian 286-248 mya

Carboniferous 360-286 mya

Palaeozoic Devonian 408-360 mya

Silurian 438-408 mya

Ordovician 505-438 mya

Cambrian 590-505 mya

Precambrian 4,600-590 mya

(bp = before present; mya = millions of years ago)

All figures are approximate and based on currently available evidence.

 

The Beaufort Scale of Wind Speed

Equivalent speed at

10m above ground

Beaufort Knots Kilometres Description of conditions

number per hour

0 <1 <1 Calm - smoke rises vertically; sea like a

mirror.

1 1-3 1-6 Light air - smoke drifts; ripples on sea.

2 4-6 7-12 Light breeze - wind felt on face, leaves rustle, vanes moved by wind; small wavelets on sea.

3 7-10 13-19 Gentle breeze - leaves and small twigs in constant motion, light flags extend; wave crests begin to break.

4 11-16 20-30 Moderate breeze - dust and loose paper raised, small branches move; fairly frequent white horses at sea.

5 17-21 31-39 Fresh breeze - small trees sway, crested waves on inland waters; moderate waves at sea.

6 22-27 40-50 Strong breeze - large branches move, telegraph wires whistle; foaming crests and some spray at sea.

7 28-33 51-62 Near gale - whole trees in motion, inconvenience felt in walking against wind; foam at sea begins to be blown into streaks.

8 34-40 63-74 Gale - twigs broken off trees, walking upright difficult; wave crests break into spindrift.

9 41-47 75-87 Strong gale - chimney pots and slates moved; high waves at sea with rolling crests and dense spray.

10 48-55 88-102 Storm - trees uprooted, considerable structural damage; sea appears white with high overhanging waves and streaks of dense foam.

11 56-63 103-117 Violent storm - very rare on land, causing widespread damage; sea covered in foam patches, with waves high enough to hide medium-sized vessels and with crests blown into froth, visibility affected.

12 >=64 >=118 Hurricane - sea completely white, with driving spray, the air filled with foam and spray, visibility seriously impaired.

The use of the terms ‘gale’ and ‘storm’ is not completely standardized.

1