HERTFORDSHIRE NATURAL HISTORY SOCIETY. 
XX? 
one end of which, went down the well and terminated in a plumber’s 
ordinary hollow ten-inch copper hall' floating on the water; the 
other end being only a few feet long, and terminating in a counter¬ 
poise. As the water rose and fell, the chain moved up and down, 
and a little pointer fixed on the part of the chain opposite the post 
pointed to the feet and tenths of a foot marked on the post. The 
sea-level, or national ordnance datum, was obtained from an ad¬ 
jacent ordnance bench-mark conjoined with the corresponding 
figures on the "Watford sheet of the ordnance map. He would he 
happy to show the simple apparatus to anybody at any time. Water 
flowed into his well very slowly, hence there was a temporary fall 
in the level after each pumping, hut his household drew so small 
an amount that the water again reached the maximum height within 
24 hours, so that records, even if he took them daily, would he 
thoroughly trustworthy. 
Mr. S. Monckton White said that there seemed to he a difference 
in the different parts of the county. He had a well at St. Albans 
about 50 feet deep. About three years ago there was so little 
water in it that he had to sink an artesian well and to put in a 
pipe much deeper, and he had had more water in 1888 and 1889 
than for the previous four years. 
Dr. Brett said that observations made by Mr. George Wailes at 
the London Orphan Asylum showed nearly the same results as 
those stated by Professor Attfield. Presuming the water to he 
distributed in the way Stephenson stated, they might consider 
Odsey as being situated at the top of a cup, and Watford at the 
bottom. He thought therefore they might expect a greater varia¬ 
tion in the water-level in the wells at Odsey.* The Rev. James 
Clutterhuck, who was the father of hydro-geology, once told him 
that it takes an inch of rain to saturate the ground, or, so to speak, 
lay the dust, after the summer. 
The Chairman expressed the hope that Professor Attfield would 
communicate to them exact particulars as to his observations. He 
did not know how far they might feel the effect of the borings in 
the valley of the Colne, hut in his neighbourhood the question was 
becoming rather serious, and he was not at all certain whether, if 
Professor Attfield’s well had been in the Lea valley, he would not 
have found a considerable difference. He might suggest that the 
series of borings in the Lea valley might even affect the water- 
level as far as Royston. He knew several wells and even ditches 
that had been drained dry, and several streams that used to be 
•water-cress beds also now dry, and the only cause that he could 
assign for it was the taking of the water for the supply of London. 
* The true explanation of the greater variation in the water-level in the 
Chalk at a distance from a river than close to one, has been pointed out by Dr. 
John Evans. It is that the surface of the .saturated portion of the Chalk is 
an inclined plane sloping to the nearest point of -discharge. By the side of a 
stream with springs rising in its bed the variation in the water-level will he 
practically nil, hut the. difference between the level, in dry and wet seasons will 
increase with the distance from the point'of discharge.— Ed. 
vol vi.—PART VII. 
c 
