556	NIOHOLLS'S   SEAMANSHIP   AND   NAUTICAL  KNOWLEDGE
EXAMPLES FOR EXERCISE.
I.	The external and internal diameters of  a steel tube 14 feet long
are 12 inches and 10 inches respectively, find (1) the volume of the
enclosed space, (2) the volume of the steel forming the tube, (3) the
weight of the tube, the specific gravity of steel being 7-84
2. An awning is 25 feet long and 15 feet wide, find its area and the
length of the rope round its edges.
3 A jib is laid flat on deck. The foot measures 20 feet long and
the length from foot to head, measured perpendicular to the foot, is 40
feet. Required the number of square yards of canvas in the sail.
 4.	A boat's standing lugsail has the following measurements:—
Head 10 feet, luff 8 feet, foot 12 feet, after leach 16 feet, diagonal from
throat to clew 14 feet.    What is the area of the lugsail?
 5.	A prohibited area, triangular in shape, is marked ofi in a harbour
by three buoys, A, B and C.    The distance from A to C is 300 yards,
from B to C 400 yards, and the horizontal sextant angle at buoy C
subtended by the buoys A and B is 45°.    Required the area of the
enclosed space.
 6.	Find the surface area of a rectangular case measuring 6 feet
long, 3 feet broad and 2«5 feet deep.
 7.	Find the surface area of an oil drum 2 feet high, its diameter
being 1 foot.
 8.	Find the total surface area of a wedge of  height 3 feet, slant
length 5 feet, base length 4 feet, breadth 2 feet.
 9.	Find the volume of a tank 10 feet long, 8 feet broad and 20 feet
deep     How many gallons of fresh water will it hold?
10. Find the volum* of a cylinder whose  length  is   12  feet  and
diameter 6 feet.    Refer to the figure of a cylinder.
II.	Find the gallons of fresh water contained in a barrel 3 feet long
whose bilge diameter is 2 feet and head diameter 1J feet.
 12.	A wedge-shaped heap of coal is piled up in a ship's hold against
a bulkhead to a height of 10 feet and extending along the ceiling for
15 feet, the breadth being 30 feet.    Find how many tons there are,
assuming 42 cubic feet to the ton.
 13.	A ship sails a circular course round a point and maintains a
constant distance of 4 miles from it until the point alters its bearing 49°.
Required the distance sailed.