The advantages of this recorder are: (1) It is suitable for both 

 laboratory studies and sea-wave recordings; (2) this type of recorder 

 responds well to waves of all frequencies and can follow the rise and 

 fall of the water surface with negligible error; and (3) the performance 

 of the capacitance-wire electrode is fairly reliable and comparatively 

 free from the action of the sea water. 



c. Resistance wire wave staff 



This instrument was built for the Hydrographic Office by the 

 Atlantic Research Corporation. The component parts, shown in Figure 

 VII- 3, consist of an oscillator, a vacuum tube voltmeter, a recording 

 milliammeter, and a continuous length of Chromel wire which is strung 

 through a telescopic stainless steel tube. The resistance of the Chromel 

 wire changes linearly as the sea water moves up and down its length. 

 A full scale deflection equivalent to 1 5 feet of wave height is possible 

 on the recorder. 



Since the diameter of the wire is small, the sea water tends to drain 

 off rapidly as the trough of a wave passes the gauge. Thus, the a wetting n 

 problem which has troubled the operation of other fixed wave gauges 

 in the past is overcome. This instrument is in successful use by the 

 Hydrographic Office on one of the Texas Towers. 



D. CONCLUSIONS AND RECOMMENDATIONS 



Ocean surface waves may vary from very short capillary waves 

 (ripples) to very long tsunamis (waves generated by submarine earth- 

 quakes). Of great practical importance to the Hydrographic Office are 

 those wave groups whose periods range from 1 to 30 seconds. This 

 Office currently is investigating the properties of such waves by 

 measuring them with bottom pressure recorders, floating measuring 

 devices, fixed wave staffs, and air-borne instruments; such data are 

 useful to the study of undersea warfare problems. Further wave data 

 also are required to study the behavior of undersea weapons and to 

 check the theories that are used in wave forecasting. Some of the 

 instruments described in this Section are in active use whereas others 

 are still in the test and developmental stages. 



1. Bottom pressure instruments 



Of the various bottom pressure wave recorders that have been 

 discussed in this Section, the Wiancko pressure measuring system, 

 the Mark I, Mod 4 acoustic system, and the Mark IX shore wave 

 recorder all have stood the test of time. Of these three instrument 



VII- 14 



