Measurement of Length 21 



be 22 yds. long, if the pitch were actually laid out by means of 

 such a tape-measure ? 



3. A tennis court is 78 ft. long and 36 ft. wide. How many 

 metres does the marker travel in marking out the lines around the 

 outer edge of the court ? If the radius of the marking-wheel is 

 3| in., how many times does the wheel revolve in whitening one 

 long edge ? 



4. The minute hand of a clock is 4" long and the hour hand 

 2". In how many hours will the tip of the minute hand have 

 travelled a mile and how many times must the hour hand travel 

 round the clock-face before its tip has covered the same distance ? 



5. An ebony ruler is 10" long and has a diameter of 1". How 

 many feet of string must be wound around the ruler, with the coils 

 just touching, to cover it with a layer of string from end to end, 

 the diameter of the string being 0'1" ? 



6. Write a clear description of the method you would adopt 

 in determining the thickness of the material of a coffee-pot. 



7. What is a *' vernier " ? How would you construct a vernier 

 for use with a foot-rule divided into tenths of an inch, so as to obtain 

 measurements to the nearest hundredth of an inch ? 



CHAPTER II 



MEASUREMENT OF AREA AND VOLUME 



15. Before dealing with the units of area, and the 

 methods used in measuring areas, we must know 

 exactly what is meant by an area. The area of a 

 figure is the size of the surface bounded by the line 

 or lines which make up the sides of the figure. In this 

 book we shall only deal with areas all points of which 

 lie in the same plane, i.e. with areas marked out on 

 a flat .surface. Thus each square in Fig. 7 is a plane 

 figure, as long as the page is kept flat, but if the page 



