310 



KELVIN 



for model and for the meteorological analyser, now at work 

 in the Meteorological Office, is here before you. It has five 

 disk-globe-and-cylinders, and shafting geared for the ratio 

 1 : 2. Thus it serves to determine, from the deviation curve, 

 the celebrated "A B C D E" of the Admiralty Compass 

 Manual, this is to say, the coefficients in the harmonic ex- 

 pression 



A-f B sin 0+C cos + D sin 2 0-f-E cos 2 0. 

 for the deviation of the compass in an iron ship. 



The first instrument which I designed and constructed 

 for use as a Tide Predictor was described in the Catalogue 

 of the Loan Collection of Scientific Apparatus at South 

 Kensington in 1876; and the instrument itself was presented 



FIG. 133 Tide Predictor 



by the British Association to the South Kensington Museum, 

 where it now is. The second instrument constructed on the 

 same principle is in London, and is being worked under the 

 direction of Mr. Roberts, analysing the tides for the Indian 

 ports. The result of this work is these books (Tide Tables 

 for Indian Ports) in which we have, for the first time, 



