The Harmonic Analysis of Tidal Observations 319 



1876 is in the South Kensington Museum in London. Similar machines have 

 been built later by the Government of the Indies, by France (Michel-Morot, 

 1908, p. 394), by the USA (1918) and by Germany (Rauschelbach, 1924, 

 p. 285). The latest machine, which can take care of 62 partial tides, has been 

 completed in Germany in 1938. The construction of all these machines is 

 based essentially upon the following features. System of gearing by means 

 of which shafts representing the different components are made to rotate 

 (see Figs. 128 and 129) with angular speeds proportional to the actual speeds 

 of the components; then, a system of cranks and sliding frames for obtaining 

 harmonic motion. Then, summation chains connecting the individual com- 

 ponent elements, by means of which the sums of the harmonic terms are 

 transmitted to the recording device. Furthermore, there is a system of dials 

 and pointer for indicating in a convenient manner the height of the tide for 

 successive instants of time and also the time of the high and low waters. 

 Furthermore, a tide curve of graphic representation of the tide automatically 

 constructed by the machine. To set the harmonic constants, the registration 

 of the time and height of about 1400 high and low waters in print for a year 

 requires approximately 10-15 h according to the complexity of the tides 

 in the locality concerned (see Shureman, 1924, p. 123). 



