184 
TATE : SOURCE OF RIVER AIRE. 
than the Cove from the " Watersinks," and 117 feet lower, 
yet the water liberated from the Tarn reached Airehead 38 
minutes sooner than it reached Malham Cove. This will be 
better understood if we observe what occurred above the 
" Watersinks," in the open stream. On the second day, the 
waters, having a widespread and shallow channel, required 
seven minutes longer to travel the comparatively level half 
mile between the Tarn and the Sinks than they needed on 
the preceding day, when the channel was practically limited 
and deeper. In like manner, the difference in contour of the 
two subterranean passages, connecting respectively the sink 
which supplies the Cove and the sink whose contents flow to 
Airehead, will explain the delay in question. A broad but 
shallow watercourse to the Cove, with a narrow and deep 
fissure to Airehead, will meet all the requirements of the 
case. 
The theory that Malham Cove is supplied by the stream 
which disappears at the Streets Smelt Mills is sufficiently re- 
futed by our analyses. It is impossible to believe that water, 
flowing undiluted through a mile and three quarters of lime- 
stone strata, should during its voyage lose between two and 
three degrees of hardness, as must be the case if these two 
streams are continuous. The Airehead water (Appendix C) 
receives surface drainage. Besides, the volume of the Smelt 
Mills syke is not a twentieth that of the Cove stream. 
Pike Daw is still less likely to be the source of the Cove 
waters. It lies one mile W. 20° S. of the Cove, all the inter- 
vening strata dipping to the south, and conducting the 
drainage off Pike Daw to a lower point in the river. 
We may therefore fairly conclude that Malham Tarn, 
with its feeders draining Fountains Fell, is the natural source 
of the River Aire. We must not forget, however, that the 
surrounding area is honeycombed with joints, fissures, or 
watercourses, ramifying far away to the north where the lime- 
