SEA-FISHERIES LABORATORY. 133 



show, on the whole, the greatest differences in mean temperature 

 at the two light vessels in question, though the exceptional 

 nature of the conditions is not so strikingly shown as in the 

 dates of the minima. Now it has been suggested that the 

 general weather conditions act on the coastal strip of water 

 between tide marks* to a much greater extent than on the 

 water of the sea ; but the change in temperature of the banks 

 then acts on the sea (in some years, in the past, Morecambe 

 Bay has had much ice on the banks in the winter months). 

 This effect of the banks on the coastal sea- water is also shown 

 by the rapid rise in sea-temperature in 1907, during February 

 and March, when there was abundant sunshine and an air- 

 temperature higher than the normal for this time of year. 



There are, however, many factors which are bound to 

 affect the temperature of the sea in such an area as Morecambe 

 Bay. These conditions must be very complex, and it can 

 only be during spells of exceptional weather, when one or a few 

 factors predominate, that it is possible to trace out connections 

 such as we are anxious to elucidate. 



The heating and cooling of the sea- water in the Morecambe 

 Bay area must, however, be largely influenced by the flowing 

 and ebbing of the tides over about 100 square miles of sand, 

 uncovered every twelve hours. Now, since the spring tides 

 cover and uncover a larger area of sand-banks than do the 

 neaps, it was thought possible that there might be a correlation 

 between the deviations from the mean sea-temperature (as based 

 on the ten-daily averages) and the succession of neaps and 

 springs. Morecambe Bay Light Vessel is about 16 miles distant 

 from the mouth of the Bay, and its position is such that it is 

 not far from the main course of the floods and ebbs. (The 

 tide from the north part of the Bay, however, streams north 

 and south along Walney, and does not pass close to the ship.) 

 There is a mass of water, however, flowing past the ship, for nine 



* Which is, of course, enormous in Morecambe Bay. 



