39. Why is a knowledge of drawing essential to a workman? What is the difference between a photograph, or a perspective sketch, and a working drawing? What is the object of a working drawing?

40. How many views of an object are generally necessary? State exceptions. Describe the mental process by which a draftsman determines the different views of an object.

41. Read and explain a working drawing. Describe sections, and the methods of indicating them. Describe and explain the purpose of breaks in a drawing.

42. What is the purpose of a center line?

43. How are radical dimensions shown?

44. Should the workman scale a dimension which is indicated by figures? How do draftsmen generally change a drawing if it is necessary? How much attention should be paid to explanatory notes upon a drawing ?

45. How should a workman think of measurements when scaling? What are the usual scales? Why are not 1/2" and 1" scales generally used upon woodwork? What is the scale commonly used upon plans and elevations of medium-sized buildings? What scales are used for details? Mention cases in which full-sized details are made. Describe and demonstrate the process of using the scale. Demonstrate the method employed in using an ordinary rule for scaling.

46. Describe the tools used in mechanical drawing. Demonstrate the use of the different instruments to obtain various results. What tools should be used to guide a pencil in drawing a line? Why not use a rule?