1880.] representation of logical propositions. 59 



therefore the eye cannot conveniently gather them up into single 

 groups. In fact such a plan almost necessarily leads to that 

 primitive arrangement proposed by J. C. Lange, and mentioned at 

 the outset of this paper. Whatever elegance logical diagrams 

 can possess, and whatever aid they can give to the mind through 

 the sense of sight, seem thus to be forfeited. 



My own conviction is very decided that all introduction of 

 considerations such as these should be avoided as tending to 

 confound the domains of Logic and mathematics ; of that which 

 is, broadly speaking, qualitative, and that which is quantitative. 

 The compartments yielded by our diagrams must be regarded 

 solely in the light of being bounded by such and such figures, 

 as lying inside or outside such and such lines. We must abstract 

 entirely from all consideration of their relative magnitude, as 

 we do of their actual shape, and trace no more connection between 

 these facts and the logical extension of the terms which they 

 represent than we do between this logical extension and the size 

 and shape of the letter symbols, A and B and C. 



On the beds at Headon Hill and Golwell Bay in the Isle of 

 Wight. By E. Tawney, M.A., Trinity College, and H. Keeping 

 of the Woodwardian Museum. 



The authors upheld the work of the Geological Survey, and of 

 the late E. Forbes in this district, maintaining the correctness of 

 the Survey Memoirs on the Isle of Wight and of their Horizontal 

 and Vertical sections (except in the case of a few minor details). 

 These however have been lately written against by Prof. Judd 

 {Quart. Joum. Geol. Soc. xxxvi. p. 137), who disputes their identi- 

 fications and stated succession of the beds in Totland and Colwell 

 Bay ; introducing two new series — a marine and a freshwater — at 

 Headon Hill, in addition to those which have been universally 

 accepted for the last quarter of a century. 



Prof. Judd's section differs materially from that of the Geo- 

 logical Survey as regards the position of the marine series known as 

 the "Middle Headon," or "Middle marine;" this series he places 

 at the sea-level near Widdick Chine at the N.E. corner of Headon 

 Hill. Consequently between the top of the marine bed and that of 

 the Bembridge limestone, there would be on this theory 250 feet 

 of beds, for such is the altitude of the cottage on the Warren mark- 

 ing the summit of the Bembridge limestone. The authors however 

 dissent from this, and argue that the thickness stated must be 

 reduced by about 105 feet; viz. the altitude of the top of the Mid- 

 dle Headon at this point: this 105 feet of beds — another freshwater 

 and another marine — have no existence in fact, and in Prof. Judd's 



