614 EEPORT 1881, 



FRIDAY, SEPTEMBER 2. 



The following Papers were read : — 



1. On the Ivjluence of Barometric Pressure on the Discharge of Water from 

 Sprinys. By Baldwin Latham, M.Inst.G.E., F.G.8., F.M.8. 



The author of this paper mentioned that it was alleged, by some of the long- 

 establisihed millers on the chalk streams, that they were able to foretell the ap- 

 pearance of rainfall from a sensible increase in the volume of water flowino- down 

 the stream before the period of rainfall. He had, therefore, undertaken a series 

 of observations to investigate the phenomena, and he found, in settino- up o-au^es 

 on the Bourne flow in the Caterham Valley, near Croydon, in the spring of this 

 year (1881), and selecting periods when there was no rain to vitiate the results, 

 _that_ whenever there was a rapid fall in the barometer, there was a correspond- 

 ing increase in the volume of water flowing, and with a rise of the barometer, 

 there was a diminution in the flow. The fluctuations in the flow of the Croy- 

 don Bourne, due to barometric pressure, had at one period exceeded half a 

 million gallons per day. The gaugings of deep wells also confirmed these 

 observations ; for where there was a large amount of water held by capillarity in 

 the .strata above the water-line, at that period of the year when the w^ells became 

 sensitive and the flow from the strata was sluggish,' a fall in the barometer co- 

 incided with a rise in the water-line, and under conditions of high barometric 

 pressure the water-line was lowered. Percolating gauges also gave similar evi- 

 dence, for after percolation had ceased and the filter was apparently dry, a rapid 

 fall of the barometer occurring, a small quantity of water passed from the perco- 

 lating gauges. The conclusion arrived at was, that atmospheric pressure exercises 

 a marked influence upon the escape of water from springs. The increase in the 

 flow of the water was attributed to the expansion and escape of the gases held by 

 the water under low barometric pressure, which caused the water to escape more 

 freely, while with high barometric pressure tliere was a condensation and inward 

 How of the gases which led to a retardation in the flow of the water. 



2. Glacial Sections at TorJc, and their relation to the later deposits. By 

 J. Edmund Clark, B.A., B.Sc, F.0.8. 



General Relation.— The York area chiefly consists of Glacial beds, which form 

 the high ground and cover the various extensive low tracts more or less remote 

 from theOuse. Glacial depressions have been filled up with brick-earths, and, 

 in exceptional cases, peat-beds. Where the river channel is narrowed below the 

 city, the crests of the banks are capped with gravels reaching on the left bank 

 below the river-level. 



Peff<-Se<fs.— Campleshon Pond and part of St. Paul's Square are peat-beds 

 where depressions were elevated above the levels covered with brick-earth. The 

 same explanation may apply to the peat at Messrs. Backhouse's nurseries. But 

 Askham Bog, li miles long by ^ a mile broad, at the far end of the Hob Moor 

 deposits, seems to be over a depression so deep and remote that the clay deposits 

 only partly filled it. Near Ouse Bridge a peat-bed 50 feet down, at Brett's 

 Brewery, has been called Interglacial ; but the beds above it cannot positively 

 be asserted to be Glacial ; for at the waterworks similar beds appear, in which 

 plant-roots were detected 20 feet down. The beds are warpy brick earths, with 

 some sand in the latter case. 



Brick-earths.— At the Harrogate Signals, \ mile further north, the junction of 

 the upper beds with Glacial (or probably Glacial) beds is seen; but the change is 

 almost insensible, although very soon true boulder clays are exposed. The junction 

 was seen better during the construction of the Foss Islands railway, the brick- 

 clays at the edge pi the marsh resting against an uneven surface of boulder clay, 

 whilst for some distance an average of 5 feet of brick-earth covers a surface con- 

 sisting of uneven boulder clay, half planed down and the hollows filled with sand. 



