SEA-FISHERIES LABORATORY. 341 



slow, and the tanks require to be cleaned out only at 

 very long intervals. The result is the production of an 

 effluent which, if the tanks are properly worked, is almost 

 clear, is non-putrescible, and which does not cause a 

 nuisance. The effluent after leaving the septic tanks 

 passes into an underground storage culvert which has a 

 storage capacity of 800,000 gallons. At the outlet end of 

 this storage culvert is a penstock chamber and a chamber 

 provided with a tidal valve. The culvert discharges into 

 a 24-inch iron pipe, the liquid in which is under pressure 

 from the head of sewage in the culvert. The culvert was 

 designed to remain full, or partially full, of effluent for 

 nine hours, and to discharge in three hours. In actual 

 practice the sewer outfall is opened three hours after, and 

 closed four hours before high water. 



The main outfall sewer runs out over the sands to 

 a point at Seldom Seen Skear at the low-water mark of 

 spring tides and there discharges. At Morecambe the 

 duration of the ebb is much greater than that of the flood. 

 At spring tides the flood lasts for 3 hours and 15 minutes 

 on the average, and at the neaps for 4 hours and 45 

 minutes. Extensive float experiments were carried out 

 to determine how far the sewage would be carried by the 

 ebb before the tide turned.* Drift bottles, and large 

 wooden floats provided with flags so that their movement 

 could be observed, were used. The information derived 

 from these float tests showed that the sewage would be 

 carried well out to sea before the turn of the tide, and 

 would not return to Morecambe. Many of the bottles 



* The Engineer's report is: — "From information derived from 

 the float tests on the 10th February, and 16th and 23rd March, 1897, 

 and between 25th of August and the 3rd September last (1898), there 

 is no doubt that the best point of discharge is at " Seldom Seen," a 

 point on the north side of the fishing baulks lying north of the Battery 

 Inn. At this point the tide at half-ebb would be sufficient to carry 

 away the sewage coming from Morecambe far out to sea before the tide 

 turned." 



