24 U. S. COAST AND GEODETIC SURVEY 



which can be wound upon the float-wire drum, which is approxi- 

 mately 30 feet. 



53. Record paper. — The record paper for the portable automatic 

 tide gage (fig. 22) consists of sheets with special cross-section rulipg. 

 These sheets are 7 inches wide and 19.7 inches long allowing for a 

 ^-inch overlap, the ruled portion being 19.2 inches long to corre- 

 spond to the circumference of the record cylinder. The coordinate 

 lines ruled parallel to the short edge of the paper provide for the time 

 scale, and those parallel to the long edge provide for the height scale. 



54. The time scale is uniformly 0.4 inch to the hour and the hour 

 lines are so spaced. The hour spaces are subdivided by lighter lines 

 into six equal parts to represent 10-minute intervals. The length of 

 each sheet is sufficient to include 48 hours which are numbered in two 

 sets from (midnight) to 23 (11 p. m.). The height scale ruling 

 varies according to the scale with which the gage is to be operated as 

 indicated by the table on page 23, proAdsions being made for five 

 different scales. For the smallest scale, 1 : 45, the sheets are ruled for 

 feet and half-feet, but for all other scales the foot spaces are sub- 

 divided into five parts, each representing 0.2 foot. Printed on the 

 margin of each sheet is a note indicating the height scale of the paper 

 and the correct gears to be used with the same. 



55. Originally the paper provided with the gage was finished with 

 ordinary sizing for use with pencil or ink, neither of which was 

 entirely satisfactory. The difficulty with the use of ink was due to 

 the large changes in humidity to which a tide station is exposed. 

 Because of the effect of excessive moisture on ordinary record paper 

 it was found impossible to obtain an ink which would give satisfac- 

 tory results under all conditions. To overcome this difficulty there is 

 now used a wax-coated paper on which the record is traced by a 

 stylus which removes the wax coating leaving exposed a colored 

 paper beneath. 



56. Float wire. — The wire used for this gage may be either phos- 

 phor-bronze or nickel-chromium. Size No. 28, American wire gage, 

 IS required to fit the grooved thread on the float drum. This is a 

 little finer than that used for the standard tide gage. 



57. Float. — The float (13, fig. 11) designed for use with the port- 

 able tide gage is a hollow brass cylinder 314 inches in diameter and 15 

 inches long. It is weighted with shot to float with the upper end 

 about 31/^ inches above the surface in sea water or about I/2 inch above 

 the surface in kerosene. The float was especially designed for use 

 in a Sy2- or 4-inch float well. The gage may also be operated with a 

 larger diameter float in a larger well. 



58. Float pipe. — There is furnished with the gage a short section 

 of 4-inch pipe 7 inches long (2, fig. 11). The upper end is machined 

 to fit into the socket in the base of gage and is secured to the latter 

 by two screw hooks (27, fig. 13) which engage in small rectangular 

 holes near the top end of the pipe. The lower end is threaded to 

 form a union with additional lengths of pipe required for the float 

 well. The gages were formerly designed for use with a 3i/^-inch 

 pipe, and in order to adapt the earlier gages for use with a 4-inch 

 float well reducing couplings are necessary. 



59. Intake coupling. — A conical intake coupling (16, fig. 11) is 

 furnished as one of the regular accessories to the portable tide gage. 

 This is installed with the apex of the cone downward. The cylindri- 



