374 HYDROGRAPHIOAL SURVEYING [chap. xvii. 



on to the former. A careful tracing having been made of the 

 working sheet, it is placed on to the fair sheet, so that the 

 points all correspond, and by means of transfer paper is traced 

 on to the fair sheet, and inked in. 



Great care is requisite, in transferring in this manner, that 

 the tracing does not move from its proper position, and heavy 

 weights must be used to prevent it from doing so. Errors have 

 often crept in from careless transferring and want of proper 

 examination and comparison afterwards. 



In working with the method recommended by the writer — 

 viz., each assistant's work plotted and inked on to his own 

 separate board, and all then placed on one tracing — the final 

 sheet can either be the original on which all the points have 

 been plotted, if that has been kept clean enough ; or a sheet 

 may be pricked through, as mentioned above, for the purpose ; 

 but in either case only one complete chart will be made, the 

 general tracing sufficing to show whether the work of different 

 assistants has met, and what is wanted to complete. 



This, or these (as in a large sheet there will be several tracings 

 for different parts), will be the tracing used for making the 

 final chart in this case. 



These tracings should not be too large, as they are apt to 

 get distorted. For fine Avork it is desirable to make small 

 tracings on paper for the special work of transferring. 



This chart will also be the work of one hand, who will, after 



transferring outline, soundings, etc., from the general tracings, 



have the original little bits before liim while inking in ; these 



little bits having been taken off their boards, and so reduced, 



by having superfluous paper cut off, as to be handy to lay on 



the sheet. 



Original By washing off the field boards, the paper will have become 



Zi^^'^ distorted and contracted, but not to a sufficient degree to inter- 

 Sheets. " 



fere with the small detail of sinuosity of the coast, which is what 



we mainly Avant for them. Everything will have been traced on 



the general tracings before the paper has been removed, and care 



must be taken that this is so, as it cannot be done afterwards. 



"Points" In whatever manner the final chart is sent in to the office, 



all " points " must be distinctly marked on it, especially main 



points. These latter are often distinguished by the triangle 



which means theodolite station, and in surveys where the 



to be 

 Shown 



