14 Domestic Science 



round the circumference. If we assume that each 

 little bit of circumference measured by one step of 

 the dividers is straight 1 , the number of steps multi- 

 plied by 2 is the number of millimetres in the circum- 

 ference of the circle. 



Repeat this measurement, having first set the points 

 of the dividers 5 mm. apart, and compare the length 

 thus obtained with that previously found. 



Fig. 4. 



Exercise for Student. 

 How do you account for any difference noted ? 



Draw two other circles with radii 4 cm. and 6 cm. 

 respectively. Measure the lengths of their circum- 

 ferences as above. 



1 This assumption involves an error which is appreciable unless the 

 length of a " step " is very small when compared with the length of the 

 circumference, or, in other words, unless the number of steps required 

 to go completely round the circumference is very large. 



