30 
force only extended over a comparatively short period, but long 
enough to prove that the Fremantle tides were extremely interesting 
from a scientific point of view and called for a series of observations 
extending over many complete years before a correct interpretation 
of their numerous anomalies could be given. In spite of this, how- 
ever, on the discontinuance of the Admiralty work nothing further 
in the way of tide-recording was attempted for many years. 
In 1900, following on recommendations by Captain Irvine, the 
Chief Harbour Master, and by Mr. Cooke, the Government 
Astronomer, a number of Bailey’s tide recorders were purchased 
and in the course of time gauges were established at Fremantle, 
Bunbury, and Albany, and later on at Port Hedland. For a long 
time the records from these gauges were stored away and put to 
no use — the result showed what a mistake this was. 
In 1911, however, a very progressive step was taken — the ap- 
pointment of a computer to undertake the compilation of these 
records. The work was commenced at the Observatory under my 
supervision, owing to absence of Mr. Cooke who was at the time in 
England. A start was made on the Fremantle figures, which, as it 
turned out, were the only ones that had been properly kept. When 
the records from the other ports came to be examined at the 
Observatory, it was found for various reasons that it was impossible 
to obtain satisfactory readings from them. 
This was much to be deplored and only proves how essential it 
is that constant and expert supervision should be kept over work 
of this nature. The figures obtained from the Fremantle records for 
the years 1908 to 1912 were compiled and finally treated according 
to the method of harmonic analysis proposed by Sir George Darwin 
and the one now universally adopted. A brief explanation of this 
method and the results of the analyses appear at the end of this 
paper. 
The Port Hedland Tide Gauge and Records. 
As already mentioned, the records taken at the above port were 
found to be valueless, not only on account of the number of breaks 
in the records, but because the scale of the Bailey tide gauge was 
far too small and proved quite inadequate for the registration of 
such a wide range of tide as is experienced at Port Hedland. It 
was therefore decided to have a gauge of more suitable design con- 
structed, and Messrs. Jones & Co., of Perth, under the supervision 
of Mr. Yeates, of the Observatory, were entrusted with the work. 
The new gauge — a photograph of which is reproduced (vide 
Plate IX., Fig. 1) — departs somewhat from the usual form 
of tide-recording instrument, in that it is the pencil, and 
not the drum, which is operated by clock-work. The drum 
itself is directly attached to the tide-float and turns back- 
wards and forwards as the float rises and falls with the 
tide. In order to eliminate wave action the float is free to pass 
up and down an enclosed cylinder which at Port Hedland consists 
