ON THE HARMONIC ANALYSIS OF TIDAL OBSERVATIONS. 35 
Third Report of the Committee, consisting of Professors G. H. 
Darwin and J. C. Apams, for the Harmonic Analysis of Tidal 
Observations. Drawn wp by Professor G. H. Darwin. 
I. Recorp or WoRK DURING THE PAST YEAR. 
THe edition of the computation forms referred to in the second report is 
now completed, and copies are on sale with the Cambridge Scientific 
Instrument Company, St. Tibbs’ Row, Cambridge, at the price of 2s. 6d. 
each. Some copies of the first report, in which the theory and use of 
these forms are explained, are also on sale at the same price. A few 
copies of the computation forms have been sent to the librarians of some 
of the principal Scientific Academies of Europe and America.! 
In South Africa, Mr. Gill, at the Cape, and Mr. Neison, at Natal, are 
now engaged in reducing observations with forms supplied from this 
edition. 
A memorial has been addressed to the Government of the Dominion of 
Canada, urging the desirability of systematic tidal observation, and the 
publication of tide-tables for the Canadian coasts. There seems to be 
good hope that a number of tide-gauges will shortly be set up on the 
_ Atlantic and Pacific coasts, and in the Gulf of the St. Lawrence. The 
observations will probably be reduced according to the methods of the 
British Association, and the predictions made with the instrument of the 
Indian Government. 
Major Baird has completed the reduction of all the tidal results obtained 
at the Indian stations to the standard form proposed in the Report of 1883, 
and Mr. Roberts has similarly reduced a few results read before the 
Association by Sir William Thomson and Captain Evans in 1878. All 
these are now being published in the ‘ Proceedings of the Royal Society,’ 
in a paper by Major Baird and myself. 
A large number of tidal results have been obtained by the United States 
Coast Survey, and reduced under the superintendence of Professor Ferrel. 
Although the method pursued by him has been slightly different from that 
of the British Association, it appears that the American results should be 
comparable with those at the Indian and European ports. Professor 
Ferrel has given an assurance that this is the case; nevertheless, there 
appears to be strong internal evidence that, at some of the ports, some 
of the phases should be altered by 180°. The doubt thus raised will 
probably be removed, and the paper before the Royal Society will 
afford a table of reference for all—or nearly all—the results of the 
harmonic method up to the date of its publication. 
The manual of tidal observation promised by Major Baird is now com- 
pleted, and will be published shortly. This work will explain fully all 
the practical difficulties likely to be encountered in the choice of a station 
for a tide-gauge, and in the erection and working of the instrument. 
Major Baird’s great experience in India, and the success with which the 
operations of which he has had charge have been carried out, render his 
" Namely, the Royal Societies of London and Edinburgh, the Royal Irish Aca- 
demy, the Academies of Paris, Berlin, and Vienna, the United Coast Survey, and the 
Cambridge Philosophical Society. 
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