THE UNDERGROUND WATERS OF NORTH-WEST YORKSHIRE. 
9 
and Aire Head confirms the experiment of the rise on the first 
and second days." 
The investigators considered the connection of the Smelt 
Mill with the Cove " sufficiently refuted by their analyses," 
since their table showed the hardness of the water at the 
Cove to be 10-8 as compared with 13 1 at the Smelt Mil], 
and they regarded a loss of 2-3 in hardness in passing through 
a mile and three quarters of limestone strata impossible, besides 
which "the volume of the Smelt Mill Sike was not a twentieth 
that of the Cove Stream." They thought "Pike Daw still less 
likely to be the source of the Cove waters," but to probably 
drain "to a lower j^oint in the river." 
They agreed with a suggestion of Professor Boyd Dawkins"^ 
that a water-cave of greater or less extent probably existed 
behind Malham Cove. 
Before these experiments Mr. Leather, C.E., had tried flush- 
ing the Tarn stream and reported his results to Mr. Tate. He 
considered his experiments "proved conclusively that the water 
flowing out at the foot of the Cove is not the water which sinks 
into the ground and disappears some distance above the Cove. 
The water comes out at Aire Head." 
At the British Association Meeting in 1890, at Leeds, 
Professor Sylvanus Thompson, F.R.S.,! reported having intro- 
duced one and a quarter pounds of uranin into one of the 
Malham Tarn Sinks, but without any result within three hours 
at Aire Head, or anything distinctive at Malham Cove, and he 
concluded either there was a considerable body of water at some 
intermediate spot between the water-sink and the Cove, or that 
the Aire Head spring communicated with some other water-sink 
than that marked on the Ordnance Survey maps. 
In the handbook prepared for the same meeting. Professor 
L. C. Miall, F.R.S., says that when the Tarn waters are suddenly 
*"Cave Hunting" (1874). 
t British Association Report, 1890. 
