XXX 



apparent cause the tide will commence to 

 rush into the harbour day and niuht with 

 great force, until the water at Strahan and 

 the Gordon has risen from 8ft. to some- 

 times oft., then it will start to ebb out 

 with great velocity, sometimes ebbing for 

 two or ihree days, with just a slight check 

 at high water of the sea. Seafaring people 

 say that when Hood tide is pouring into 

 the harbour bad weather is api^roaching, 

 although at times it does so and no bad 

 weather follows. It is true, however, that 

 rough weather from the N.W. makes a 

 strong inrush of the tide, causing the 

 water to rise very high in the lagoon, and 

 impounding the' fresh water poured into 

 it by the rivers, and as soon as the gale 

 veers to the AV. and S."\V. the impounded 

 water ebbs out with astonishing velocity 

 and force, notwithstanding that the gale 

 is unabated in strength. About the 26th 

 of October, ISOT, during a moderate gale at 

 N. W. the flood tide poured into the harbour 

 day and night for two or three days, till it 

 filled up at Strahan 5ft. above ordinary 

 level. The gale then increased to a heavy 

 gale at W., and the harbour gave signs of 

 ebbing ; then it ble^v a very heavy gale at 

 ^V.S.W. with a mountainous sea and tre- 

 mendous breakers in the ofHng. Imme- 

 diately the lagoon started to ebb in 

 earnest, and on the evening of the 30th 

 there was the most furious ebb tide I ever 

 saw — the water roared in a cataract be- 

 tween Entrance Island and the Peninsula, 

 and I do not think any steamer could 

 have stemmed it. At 1 o'clock in the 

 morning the ebo slackened, but at 8 a.m. 

 it was still ebbing strongly. In the after- 

 noon there was a repetition of the previous 

 violent ebb, but not so strong ; and next 

 day the ebb was exhausted, although the 

 S.W. gale had abated very little. This 

 was a great gale, which lasted over a 

 week ; during its heiaht I was astonished 

 at the immense height of the breakers, 

 and tried to fix the position of a line of 

 heavy rollers with a sextant. When fine 

 weather came I \vent in a steam launch to 

 about the place where the breakers had 

 been, and found there over GUft. of water. 

 Here I noticed what is often observed at 

 both Greymouth and Westport— that the 

 heavier the gale is apparently so much the 

 smoother is the bar ; the case being that in 

 a strong gale the waves are all broken up 

 in deeper water outside, and those which 

 reach the bar are moderately small waves. 

 At any rate, during the height of this gale 

 the steamer Australia came in over the bar 

 without any trouble, although it was a 

 marvel to me how she ran through the 

 lines of immense breakers outside the 

 bar, and this part of her performance I did 

 not see. 



Returning to the curious action of the 

 tide in Macquarie Harbour, it may be ob- 

 served that this great tidal backwater 



acts like a sort of gauge, or barometer, ta 

 show up pulsations in the sea which could 

 not otherwise be detected. Recent careful 

 observations in the Lake of Geneva h.-jve 

 shown that the surface of the lake rises 

 and falls in a very mysterious manner, 

 sometimes at one end and then at the 

 other, sometimes in the middle and not at 

 the sides. This has been supposed to be 

 due at times to local winds, or to varia- 

 tions in the pressure of the air, even to 

 part of the lake being covered with cloud 

 and part not so covered, or to the passing 

 of a distant steamer ; but. in the absence 

 of any of these supposed causes, the 

 phenomenon remains unexplained. Now, 

 if a lake acts like this, how much more 

 may we suppose the sea to be liable to the 

 same effects, which may help to explain 

 the mysterious ebbing and flowing in 

 Macquarie Harbour, often without appa- 

 rent cause, when the harbour is seen to be 

 ebbing out while the tide is rising, and 

 flowing in when the tide is falling, or at 

 times a powerful flood tide rushes in with- 

 out any reason given from the sea tides, or 

 fi'om any apparent change in the weather. 



Another interesting although wed- 

 known eftect is seen in this harbour, called 

 the throttling of the tides. In still weather, 

 when no abnormal action is taking place, 

 a rise of tides at the Heads of, say, 2ft. Gin. 

 will raise the water at Strahan or the 

 Gordon only about 1ft., so that the water in 

 the lagoon neither rises so high nor falls so 

 low as it does in the sea. This happens 

 because the sea cannot get over the bar 

 and the shallow parts near the en- 

 trance in time to fill up the harbour 

 before the tide begins to fall, and, 

 contrariwise, the water cannot get out 

 quick enough before the tide at sea begins^ 

 to rise. If the bar and the channel 

 through the shoals were considerably 

 deepened, the throttling of the tides woulp 

 be greatly lessened, with the ettect of 

 causing still more sea water to pass in and 

 out, and so increasing the scour ; in Grey- 

 mouth, New Zealand, after the completion 

 of the breakwaters, and the bar had 

 deepened from 6ft. or Sft. to 22ft., it 

 was found that the low water level at 

 two miles from the entrance had fallen 

 nearly 4ft., while the H.W. level re- 

 mained the same. After noticing the 

 strength of the currents which flow in 

 and o\it of Macquarie Harbour, it is to be 

 observed that there is absolutely no 

 current one way or the other in the 

 harbour : the body of water is so deeT> 

 and large that however violently the 

 tides, even when combined with great 

 floods in the rivers, may be rushing out 

 into the sea, the body of the water in the 

 harbour is quite still, its function being 

 confined to simply rising and falling in 

 surface level. 



The bar at Macquarie Harbour is 



I 



