334 Corres]3ondence — Professor O. A. J. Cole. 



a curve showing the relationship existing between the rise and fall 

 of the tide and that of the water in the well. From the position 

 of the well in question and its surroundings, possibly the ebbing 

 and flowing of the tide may produce the ebb and flow of water in 

 the well, but there are other ebbing and flowing wells so situate 

 that tidal variation can have on them no influence. Some few years 

 back I was staying at Buxton, and frequently walked to Castleton. 

 By the side of the road I noticed an ebbing and flowing well, but 

 the variations of condition did not assert themselves at stated or 

 defined times ; on the contrary, the changes were erratic. One 

 thing is certain, tides could here have no effect, since, as the crow 

 flies, the distance from the estuary of the Mersey, the nearest point 

 to the sea, is upwards of forty miles. How, then, can these variable 

 conditions be explained ? On the spot I could collect no infor- 

 mation. The theory I propounded was this. The district is Lower 

 Carboniferous Limestone, and, taking into account the results of 

 the chemical action of underground water, the internal composition 

 of the rocks becoine altered, large quantities are carried away, 

 with the result that subterranean tunnels and cavities are formed, 

 and if in the upper parts of this mountain limestone a spring or 

 springs exist, the overflow would find its way by tunnels into the 

 eroded cavities, from which it might be syphoned to the well below, 

 producing the changes which perplex the traveller. 



Caverns are abundant in the Carboniferous limestones. There 

 is the peak cavern at Castleton. The Victoria Cavern, at Settle, 

 Yorkshire, contains forms which favour my theory, since it has deep 

 shafts and caverns inclining inwards. There is also recorded a fissure 

 communicating with a basin in the limestone at Windy Knoll, near 

 Castleton. T. E. Knightlet. 



106, Cannon Street, E.G. 

 "^ imh, 1898. 



SACCAMMINA CARTERI AND NO DOS ARIA FUSULINIFORMIS, 

 Sir, — In consequence of the paper by Mr. F. Chapman, in the 

 Annals and Magazine of Natural History for March, 1898, in which 

 he so properly connects Saccammina Cartei'i with Nodosaria fusu- 

 liniformis of M'Coy, I have sought for the second type-specimen 

 referred to by M'Coy. It has now been placed in the wall -case 

 containing fossil Foraminifera in the Museum of Science and Art, 

 Dublin. It fully justifies Mr. Chapman's published conclusions, 

 which were based upon the Cambridge specimen. There seems 

 no doubt that we must now accept Saccammina fusidiniformis as 

 the name of this well-known species. Grenville A. J. Cole. 

 Science and Art Museum, Kildarb Street, Dublin. 

 May 2lst, 1898. 



BOULDERS OF SPILSBY SANDSTONE. 



Sir, — In his interesting note on a boulder of Spilsby Sandstone, 



at Wimpole, in Cambridgeshire (Geol. Mag., June, 1898, p. 267), 



Mr. Cowper Keed rightly observes that no block so large, and. 



bearing such a definite proof of its origin, has previously been 



