LUALk WATKU IN IIKUTS. 7 



At some places small hollows were seen in or at the side of the 

 channel, -whicli are probably swallow-holes, and a quarter of a mile 

 north of Mimms Hall was a pool, where the stream from Potter's 

 Bar joins. 



The chief swallow-hole, or rather set of swallow-holes, in this 

 upper part of the valley, is a tliird of a mile north of Mimms Hall, 

 where there is a sharp bend in the stream-channel, so that a little 

 cliif has been cut on the eastern side. Here the water was sinking 

 in slowly at various spots on May 2, but on June 9 the place was 

 dry. Under ordinary circumstances a great deal of water must 

 find its way into the Chalk here. 



Half a mile north of Mimms Hall there was a pool in 

 June ; but before getting to this several holes were seen in the 

 channel. 



After crossing the county -boundary at Warren Gate, nearly three 

 quarters of a mile below Mimms Hall, the channel was found to be 

 grassed for a little way, and then, rather more than half-way from 

 Warren Gate to Abdale House, there is a well-marked swallow- 

 hole, which, being a little way east of the channel, acts only when 

 the stream overflows. It is to be noted that on the six-inch 

 Ordnance Map (Herts, Sheet 40) this part is called Water End, 

 as well as the hamlet just north, to which probably the name 

 should be confined. 



At the true Water End, as I take it, some of the swallow-holes 

 are definitely marked on the Ordnance Map, but there are many 

 others : indeed, the open tract between Water End and Potterell's 

 Park seems to have been specially set aside for the manufactm'e of 

 swallow-holes, the ground being pitted by them, and several being 

 well-marked funnels down into the Chalk. These were dry on 

 June 9, 1893; though at one place, just south of the footpatli 

 a little N.N.E. of the Old Maypole, I saw some liquid, which, 

 however, was not water but sewage, not exactly an advantageous 

 addition to underground water. 



Below this I have seen no swallow-holes, and did not follow 

 much of the diy channel, but my former colleague, Mr. A. G. 

 Cameron, has noted that on November 1, 1891, there was no water 

 northward of North Mimms Church, and on a visit with him in 

 July, 1896, the stream seemed to start where the channel crosses 

 the parish-boundary at Colney Heath. 



Turning now to side-streams on the right bank, in that from 

 Potter's Bar I found in May, 1896, three wee hollows, which maybe 

 sink-holes, just above the narrow marsh north-east of Warrengate 

 Farm, whilst just southward, along the hedge across the marsh to 



