A PROPOSED DIP PROTRACTOR 491 



and a circular arc may be used for the dip-curve. For the low- 

 angles as shown on the protractor in Fig. 1 the tangents are so 

 nearly proportional to the angles that the spacing intervals depart 

 from equality by an inappreciable amount only. There should be 

 no difficulty in reading required dip angles to the nearest two or 

 three minutes of arc with the protractor as shown, and several 

 protractors might prpvide for the whole range up to ninety degrees 

 for those requiring the higher angles. 



