8 
THE UNDERGROUND WATERS OF NORTH-WEST YORKSHIRE. 
pebbles at Aire Head." Twenty -five minutes later (5.50) the 
stream, 4 feet wide, had risen at its junction with the Aire 
4J inches ; later in the evening it rose to nearly a foot. 
Up to 5.45, one hour and forty-five minutes after leaving 
the Tarn, there was no change at Malham Cove, but on return- 
ing after dinner (time not stated) the Cove Stream, 31| feet 
wide, had risen two inches. 
At 10 p.m. the Tarn sluices were closed again, "all but an 
inch or so to keep the fish down stream alive." 
Next day, at 1 p.m., the sluices were opened again. Owing 
to the diminished volume of the stream between the Tarn and 
the sinks the water was 25 minutes in reaching the sinks, 
instead of 18 as on the previous day. The Aire Head Spring 
was afiected at 2.32, being 1 hour 32 minutes against 
1 hour 25 minutes the previous day, so that, allowing for the 
7 minutes lost before the water-sinks were reached, the results 
were the same on both days as between the sinks and 
Aire Head. By 5 p.m. the water at Aire Head had risen 
13 inches. 
The Cove on this day was affected at 3.10, that is 38 
minutes after Aire Head. "At 3.15 it had risen ^ inch; at 
3.20 1 inch; at 3.35 1 inch; at 4.5 2 inches; at 4.45 2h inches; 
and by 5.30 the stream had risen 2| inches, its outlet being 
31 J feet wide." 
On the third day "the water was permitted to flow freely 
from the Tarn during the day, and the high-water level was 
maintained both at Malham Cove and Aire Head. At 5 o'clock 
the Tarn sluices were closed again as before." 
On the fourth day "the streams at the Cove and Aire 
Head gradually subsided, and by noon the water at the Cove 
stood J inch below its normal level. At 5.45 p.m. the water 
in the Tarn had not quite risen again to the level of the sill 
of the overflow, so that this sinking of the outflow at the Cove 
