1 dram= 1.772 grams
1 ounce = 16 drams
1 pound = 16 ounces= 7,000 grains
1 stone = 14 pounds
1 hundredweight = 112 pounds (US 100 pounds)
1 short ton= 0.907 tonne = 2,000 pounds
1 (long) ton = 20 hundredweight = 2,240 pounds

Troy Weight (Precious Metals) 
24 grains = 1 pennyweight 
20 pennyweights = 480 grains = 1 ounce 
12 ounces = 5760 = grains = 1 pound 

Apothecaries' Weight 
20 grains = 1 scruple 
3 scruples = 1 dram 
8 drams = 1 ounce 
12 ounces = 5760 grains = 1 pound 

  Archaic and less frequently used linear measure 
3 hands = 1 foot 
1 span 9 inches 
1 rod, pole or perch = 16.5 feet 
40 poles = 1 furlong  
8 furlongs = 1 mile
320 rods = 1 mile 
3 miles = 1 league
 
Nautical miles and Knots
10 cables = 1 nautical mile
6080 feet = 1 nautical mile
1 Knot = 1.151 mph 
The nautical mile is defined as the average distance on the earth's surface
 corresponding to an angle of 1 minute of arc. A speed of one nautical miles 
per hour is known as the knot. The International Nautical mile is accepted 
by the Royal Navy (1970) as being equal to 1852 metres.  As the earth is 
not a perfect sphere, but is an oblate spheroid, the distance corresponding 
to one minute of arc will vary depending on location. The value of 6080 feet 
is a compromise and is the value as measured at some point in the English 
channel