146 Transactions. 
Art. XXI.—On the Wave Phenomena observed in Lyttelton Harbour, 15th 
August, 1868. By Captain Frep. D. Gizson, Chief Harbour Master. 
[Read before the Philosophical Institute of Canterbury, 9th September, 1868. ] 
THE evening of the 14th August was calm and clear, the aneroid stood 
29°90. An unusual stillness prevailed during the night. 
At 3.30 a.m., the tide being half-ebb, the water suddenly receded from 
the harbour, rushing past the shipping lying in the stream, and vessels 
anchored near the entrance of the harbour, at a supposed velocity of twelve 
knots. The water continued falling until 4.30 a.m., when the end of the 
breakwater was dry, at which position the average depth at low water is 15 
feet. At the before-mentioned hour, with a loud roar, a wave of about 
8 feet in height rushed up the harbour with great velocity, and at 4.50 the 
water was within 3 feet of the railway level; in other words, 3 feet above 
the highest spring tide, having risen 25 feet perpendieular in twenty minutes. 
The water at about 5 a.m. rapidly receded the second time, and at 6 the 
bottom was again visible beyond the end of the Government jetty; at 7:15 
it again rushed up in the form of a heavy ground swell, and rose rapidly to 
16 feet, and immediately commenced to fall again. At 9.30 the inner end of 
the screw-pile jetty was dry, when the reaction again took place, the water 
returning with even more velocity than at 7 a.m., until it resumed the level 
of high-water springs. Off in the stream, the water was very thick and 
discoloured, boiling up as it were from the bottom. 
At 10.15 the water rushed out with the same force for about half an hour, 
and rose again shortly after 11 a.m. to 18 feet; throughout the remainder 
of the day the water rose and fell without any regularity, sometimes at the 
rate of 3 feet per hour. Aneroid, 30:5. 
During the whole of Sunday, the 16th, there was no regularity of tide, 
the water ebbed and flowed three times in six hours; at 2.16 p-m., the proper 
time of high water, there was 172 feet, and after ebbing an hour; it rose 
again to about 17 feet at 4.15. : 
Aneroid, 30°10, stationary ; weather calm and clear; water very thick, 
and continuing to boil up in large eddies. 
Monday and Tuesday, the 17th and 18th, tides still very irregular, flowing 
one foot higher, and ebbing one foot and a half lower than the usual springs. 
Wednesday, 19th, nothing unusual perceptible. 
