CHAP. IV.] SKETCH 95 



The great thing in a sketch is to place objects fairly cor- important 

 rectly with regard to each other horizontally considered ; e.g., observe, 

 if there is a hill with a point nearly underneath it, take care 

 that the latter is drawn on the correct side of the hill, right or 

 left. Nothing is more calculated to confuse anybody plotting 

 angles from a sketch, than to find that an object drawn ap- 

 parently to one side of another object has an angle which 

 shows it should have been on the other side. Doubt is at 

 once thrown on the angle, when it is probably the drawing of 

 the sketch which is incorrect. 



When the sketch is finished resume the theodolite, using Descrip- 

 the same zero, and mark the angles on the sketch itself, noting objects in 

 what the object is, when it may be doubtful, as for instance — Sketch. 

 Chimney of red house. Right of two fir-trees. Big white boulder, 

 etc. See example of sketch attached. 



Views of distant land intended for reproduction on the pub- Views, 

 hshed chart should be drawn very accurately to scale, both 

 vertically and horizontally, from sextant angles. A con- 

 venient scale for horizontal angles in a long sketch is 0-2 inch 

 to a degree, and for vertical angles 0-3 inch, or even larger. 

 In sketches for leading marks, and where the portion of coast 

 embraced is not large, the scale sliould be larger. The posi- 

 tion from which a sketch is taken should always be noted 

 upon it. 



Photography may often usefully be employed if circum- 

 stances are favourable. 



Views are very valuable for picking up the land and identify- 

 ing landmarks shown on the chart, but the positions from 

 which they are taken should be carefully considered ; if not 

 taken from a sufficient distance seaward, they may be not 

 worth engraving. The requirements of the navigator must be 

 remembered. 



PREPARATION FOR CALCULATING THE 

 TRIANGULATION. 



It is well that a true bearing be obtained between two A Bearing 

 distant stations before plotting ; but the method of doing this for "orien- 

 will be described under observations, and as far as absolute tation of 



Chart 



necessity goes, a good compass bearing from a shore station is 



