94 



HYDROGRAPHICAL SURVEYING [chap. iv. 



Checking 

 Scale by 

 Angles. 



Preserva- 

 tion of 

 Scale. 



Useful 

 Hints for 

 Sketch- 

 ing. 



It is well for a beginner to commence by taking some rough 

 angles to check his scale, or, until he is used to it, he will 

 probably have one part of his view two or three times as big 

 as the other, which is confusing afterwards, although the proper 

 angles will be written against the prominent objects when the 

 sketch is finished. 



Always put the most distant outline on the paper first, as 

 it is far easier to keep the scale uniform if this Is done. 



Begin on the extreme left of your view, or if it is an all- 

 round view, choose a point, in the direction least required, to 

 be the left, and always work to the right. 



If the sketch is too long for one double page of the sketch- 

 book, when the right-hand end of it is reached, turn over, 

 and turn 1 or 2 inches of the last page down, so as to show 

 on the fresh page ; this will give a commencement for the 

 part to follow, and the sketch will be continuous. 



Commence by settling whereabouts on the paper some two 

 well-defined points of the distance are to be, and use these 

 after as a scale from which to measure by eye the proper 

 position of everything else. 



If taking angles to assist correct drawing, as suggested 

 above, a scale for the sketch must be decided on, say about 

 J inch to a degree, but this will vary according to the com- 

 plication of the sketch. If no divided scale is at hand, mark 

 the edge of a strip of paper by eye, which will answer the 

 purpose perfectly. 



Take an angle from some definite point of the distance on 

 the extreme left to some other, say about 20° to its right. 

 Make a dot for the first object, lay the scale or strip of paper 

 on the sketch, and dot again at the proper number of degrees, 

 and at the proper height, with regard to difference of altitude, 

 for the second object. Other angles can be taken to other 

 objects between these, and the view sketched in between these 

 dots, commencing as already said with the outhne most distant, 

 and therefore highest in the sketch. 



In sketching for this purpose, it is well to rather exaggerate 

 the height of objects, as, where there are hills, range upon 

 range, or many objects, as houses, trees, etc., at different 

 altitudes, they wiU get so crowded up as to make the sketch 

 difficult to decipher, unless this course is adopted. 



