Among these may be mentioned the inaccuracy of soundings obtained in depths of less than a hundred fathoms even when a special shoal water device was used; the likelihood of inherent erroneous soundings due to the principles of the instrument; and the personal error, because the accuracy of depth measurements depended on the skill of the operator.


Erroneous soundings. — These may be due to errors in the recorded depths, errors in reducing the soundings, or the soundings may not be in their true positions. Owing to the fact that there is little opportunity to check the various field operations as they are performed, the verifier of the smooth sheet must watch for all abnormal soundings which may constitute errors. Examples are: depth curves out of harmony with others in the locality; bad crossings; shoal soundings where none should be expected; deep soundings in shoal areas.

www.thsoa.org/pdf/hm1942/hm143c.pdf

Based on circumstantial evidence (other headlines).


FYI: According to www. mijnwoerdenbook (web address below):

G: Sondierung, Pellen, Bohren
EN: probing, prospecting by borings or trial pits, boring, test boring, sounding

suggestion


Drucksonde
Bohreinheit
Probentranport
Sonderprobe