PECULIARITY IN THE TIDES. 21 



the customary expression is, there are four hours' 

 flood, four hours' ebb, and four hours' standing water. 

 This peculiarity is seen with most distinctness at the 

 time of spring-tide, but is liable to some variation 

 from the influence of winds, &c. The water, more- 

 over, does not lie for four hours, exactly at the same 

 level ; since there is more or less of a secondary tide, 

 called the Gulder, which soon after the lowest ebb 

 rises a little, and commonly falls again (but not in- 

 variably) towards the end of the four hours of standing 

 water. This continuance of the recess of tide is very 

 useful to the naturalist, since it allows him to prose- 

 cute his examinations for a much longer period at 

 once ; though, as a per contra, the long exposure to 

 the air being more than some animals and plants 

 could bear, they are compelled to reside at a lower 

 level, and hence the low-water line around Weymouth 

 is less rich in species than on other coasts where it 

 is uncovered only a few minutes at each tide. 



COLLECTING SEA-WEEDS. 



The first point to be attended to, is the procuring 

 of living sea-weeds, the vegetable element in the com- 

 bination which is displayed in an Aquarium- And 

 this must naturally be the first thing, whether we 

 are stocking a permanent tank, or merely coUeQting 

 specimens for temporary examination, as we cannot 

 preserve the animals in health for a single day, except 

 by the help of plants to re-oxygenate the exhausted 

 water. By their means, however, nothing is easier 

 than to have an Aquarium on almost as small a 

 scale as we please ; and any visitor to the, sea- side. 



