^4 *Ihe Irish Naturalists January, 



one-sixth to allow for the effects of three consecutive dry years. As a 

 general guide it was stated that the estimate of the amount of percolation 

 in Britain was from one -fourth to one -fifth of the rainfall, though in some 

 districts it was much lower. The methods in use for the gauging of streams 

 and the estimation of evaporation and percolation were described, and 

 the changes in form and level of the plane of saturation or " water-table ' 

 discussed. 



Experimental work on the flow of water in limestone rocks which was 

 carried out by the speaker in the Ingleborough distri:t of Yorkshire, 

 under the auspices of the British Association and the Yorkshire Geological 

 Society, was dealt with and the general conclusions arrived at were 

 described. A discussion followed, in which R. "Welch, W, Gray, S. A. 

 Bennett, G. Donaldson, and the Chairman took part. 



DUBLIN NATURALISTS' FIELD CLUE. 



June 24. — Excursion to Rye Water, Leixlip. — A small party 

 travelled to Lucan by the electric tram and walked to Leixlip through the 

 Vesey Demesne. In the demesne a pit excavated in the river -gravels was 

 examined, and the conductor, J. de W. Hindi, pointed out the presence 

 of far -travelled boulders from the north of Ireland, and also of shell 

 fragments which indicated that these river-gravels had been derived from 

 the Glacial drift. From Leixlip the Canal was reached at Cole's bridge and 

 the party then walked along the north bank to Rye Water. Heavy rain 

 was now fall ng, and it was found impossible to do any botanical work, 

 but the general geological features of Rye Water were pointed out, and a 

 interesting formation of calc-sinter was examined. The party then 

 returned to Lexlip by road. 



September 9. — Excursion to Malahide. — About 20 members 

 travelled to Malahide under the leadership of J. Bayley Butler, M.A., M.B., 

 for the purpose of dredging the Sound for marine animals ; this th?y did 

 for 2\ hours, but, with the exception of a few nudibranchs collected by 

 N. Colgan, M.R.I. A., nothing of special interest was found. They re- 

 turned to town by the 5.30 p.m. train, 



October 7. — Excursion to Avondale, Co. Wicklow, — Fifteen 

 members left Harcourt Street station at 10.15 a.m., for the Avondale 

 Forestry Station, and upon arriving at Rathdrum, walked out to Avondale, 

 where they were met by J. Black and A. C. Forbes. Fortunately the 

 weather, which had been very bad in the morning, cleared up in the 

 afternoon, and enabled the members to inspect the various experimental 

 plots which are now beginning to form objects of interest to the forester 

 and arboriculturist. The effects of a severe frost experienced on June 15th, 

 when the exposed thermometer fell to 12^ F. below freezing point, were 

 still visible on Spruce, Douglas Fir, Spanish Chestnut, and other species, 

 but apart from this, the growth of most trees during the summer had been 

 good in spite of the severe drought which had characterised the season 

 of 1911. Avondale House, with its museums, class-rooms, &c., was seen» 



