SCIENCE. 
409 
4 APRIL 4, 1884. | 
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——— = 
lantic coast, since the diurnal components in 
these are very small. 
It would be impossible, in this short sketch, 
to give any idea of the theory and construc- 
tion of the machine. These, however, will 
be contained in an appendix to the report 
of the superintendent of the U.S. coast and 
geodetic survey for 1883. 
The efficiency of the machine is in general 
very satisfactory. The results given by it 
have been compared both with computation 
and observation. In a comparison with one 
