HUDLESTON AND DAVIS : EXCURSION. 
131 
It will thus be impossible for me to join you ; but I assure you 
in all honesty, that I regret it very much ; as an amateur geolo- 
gist learns a great deal from accompanying experts in the field. 
"The following notes may be of interest when you come 
into this parish, and may be new to you. Two years ago the 
Bradford Philosophical Institute came here to ascertain what 
becomes of the water of Malham Tarn after it disappears at the 
water-sinks south of the Tarn, The plan adopted was as follows : 
on the previous day I opened the sluice at the foot of the Tarn, 
and so lowered the water a foot below its normal level. Thus the 
beck running out of the Tarn became very low, almost dry, when 
we closed the sluice again, only allowing a mere trickle of water 
to run along the beck to keep the beck trout alive. On the next 
day we all compared watches, and then parties were placed to 
watch at the spring under Malham Cove and at Aire Head, the 
very strong spring which you will find marked on the one inch 
Ordnance Map, some 300 yards north-east of the farm house, 
called Kirkby Top, which is 800 yards south of Malham. Marks 
were placed in the water at each place. At 1 p.m. exactly, I 
let the tarn water out by the sluice, and it ran in a muddy stream, 
and with a rush down the beck to the water-sinks. The water- 
sinks were reached in 20 minutes ; and in 65 minutes from then 
the water began to rise at Aire Head ; in 5 minutes more the 
Aire Head was boiling up with a very turbid stream. The water 
at Malham Cove began to rise at 110 minutes from the time when 
the released tarn water reached the water-sinks, but did not rise 
much, nor was it turbid, so I infer that both Aire Head and Cove 
Springs are connected with the water sinks, but that a lower 
channel of a certain capacity communicates with Aire Head and 
another passage branching from it with the cove spring, which 
latter receives the tarn water when the Aire Head passage has 
become filled. The cove water in normal times probably comes 
from a water-sink in a pasture called Streets, south-west of the 
Tarn, but we have not been able to prove this. 
