612 MR MILNE ON A REMARKABLE OSCILLATION OF THE SEA. 



salmon fishers on the SE. side of the bay stated, that on the same day their 

 nets were driven in one direction, and instantly after in an opposite one, 

 owing to a sudden flowing and retiring of the sea. 



At Baltasound (Shetland) Mr EDMONSTONE writes me, that he had been informed 

 of the oscillation having been seen in the harbour there on the 6th July, and 

 also on the day following, though in a less degree. 



" On the 6th July it was noticed between 10 and 12 A.M. The tide was 

 ebbing. A boat had grounded, and the men were preparing to get out (of 

 the boat ?), when the tide ran rapidly in, floated the boat again, and carried 

 it onwards to land several yards farther." 



" The horizontal distance that the water reached, was about 50 to 60 yards ; 

 the vertical about 3^ feet." 



"The flood retired again speedily to its first limit ; and this alternation went 

 on five or six times, perhaps oftener, for the observers did not wait until 

 they ascertained that all irregularity bad ceased." 



" The wind was NE. ; the weather dry and mild through that day and night. 

 The boats went off to the deep sea fishing, and experienced nothing unusual. 

 The sea was calm." 



" The appearances I have stated were noticed in other harbours and inlets in 

 this island. My accounts from Lerwick are as follows : ' The time the cir- 

 cumstance was first observed was noon, on 5th July, * low water or nearly so. 

 The first feature was a flowing or returning of the sea ; vertical depth about 

 3 feet ; ebbing and flowing repeated perhaps seven or eight times. Retiring 

 was the last feature. About ten or twelve minutes, might be the periods 

 between the different turns of the tide.' " 



At the Start Lighthouse (in the Orkneys) the oscillation appears to have been 

 noticed first at 3 A.M. on the 6th July. Mr LYALL, the lighthouse-keeper 

 there, states that " the flowing and ebbing continued for two days, but that 

 after 3 P.M. on the 7th July it diminished. The interval between the ebbing 

 and flowing, was from five to ten minutes. On the 6th July the sea was calm, 

 but on the 7fch July it was much agitated. On the 7th July, during the fore- 

 noon, some people were going to the cod fishing, who relate that their boats 

 were floated and grounded several times, by the rising and falling of the sea, 

 before they could get out. The same phenomenon was observed in Otterswick. 

 There was a great deal of thunder and rain on the night of the 5th July," * 



1 I think that there is a mistake here for the 6th July, for on the 5th July it was low water at 

 10 h 36' A.M., and on the 6th July at ll h 41' A.M. 



2 For this report, and all the others from lighthouse-keepers, quoted in the subsequent parts of 

 this paper, I am indebted to Mr STEVENSON, the engineer of the Northern Light Commissioners. And 

 I take this opportunity of acknowledging the readiness and liberality with which these authorities under- 

 took to obtain for me returns from all the lighthouse-keepers under their superintendence. 



