50 U. S. COAST AND GEODETIC SURVEY 



screw which has forced the pencil arm downward and caused the 

 pencil point to dig into the paper. The softening of the paper by 

 damp weather may be a contributing factor. See paragraphs 129-131 

 for cleaning pencil screw. An improper adjustment of the hour- 

 marking device whereby the tripping rod presses too tightly against 

 the tripping hook may also result in a tear. A tear along the datum 

 line suggests too great a pressure, too hard a pencil, or a broken pen- 

 cil point. A tear along the line of prick points at the margin of the 

 paper may result from too heavy a tension weight or too strong a 

 resistance from the tension springs acting upon the supply roll of 

 paper. A torn margin may result from an improper alinement when 

 the tide roll is installed on the gage. 



153. Failure to trace curve. — Sometimes sections of the tide curve 

 will be missing without any apparent cause. Assuming the pencil 

 point to be unbroken, if the missing section occurs on a falling tide, it 

 is probably the result of a dirty pencil screw which has lifted the 

 pencil off of the paper temporarily. In some cases the pencil arm 

 may be thrown entirely back away from the paper and remain there 

 until returned to its proper position by the observer. The obvious 

 remedy is the cleaning of the pencil screw in accordance with para- 

 graphs 129-131. If the entire tide curve is tery faint, a pencil with 

 softer lead should be used. 



154. Distortion of tide curve. — A series of steps in the record or a 

 flattening at the times of high or low water is most frequently caused 

 by t. dirty pencil screw and this should be given first attention when 

 the trouble arises. An irregular distortion m the tide curve may also 

 result from the same cause. In very cold weather, a distortion of 

 the curve may be caused by the presence of ice in the float well. Ice 

 collected on the inside wall of the well may impede the movement of 

 the float without stopping it completely, thus causing an irregular 

 movement. See paragraphs 71-72 for precautions against freezing. 

 If ice has already formed in the well a liberal use of salt or hot water 

 is helpful in freeing the float. If an insufficient quantity of kerosene 

 has been placed in the well as a precaution against freezing it is possi- 

 ble for ice to form below the kerosene. See also the following 

 paragraph. 



155. Clogged float well. — A clogged float well is evidenced by a 

 consistently smooth tide curve regardless of any roughness in the 

 water outside. As a clogged well causes a lag in the record which 

 greatly impairs its value, it is important that the observer be especially 

 watchful for any indications of this trouble in order that it may be 

 remedied without delay. Unless the surface of the outside water is 

 quite smooth, there should always be a perceptible short period wave 

 oscillation in the record with an amplitude increasing in proportion 

 to the roughness of the outside water. Whenever there is any evi- 

 dence of the float well being clogged, the observer should follow the 

 instructions in paragraphs 132-135 for clearing the intake. In 

 localities where the clogging occurs frequently, the observer should 

 adopt the practice of clearing the intake at regular intervals. 



INSPECTION OF TIDE STATION 



156. In making an inspection of a primary tide station note should 

 be made of the following matters and a report of the conditions found 

 forwarded to the office in form 681, report — tide station. Informa- 



