730 PROF. J. W. JUDD ON THE NATURE AND RELATIONS OF 
sham, M.Inst.C.E., and his son, my former pupil, Mr. Collett 
Homersham, F.G.S., for studying the beds as they were succes- 
sively passed through. This task has been rendered the more easy 
by my residence in the immediate neighbourhood of the well. 
Fortunately I found, upon inquiry, that the records of the previous 
work had been so admirably kept, and the series of specimens 
obtained was so complete, that I had no difficulty whatever in 
recognizing the limits of the Tertiaries, Chalk, Upper Greensand, 
and Gault with the greatest exactness. Further than this, I had 
the good fortune to obtain evidence of the existence of remarkable 
‘* junction-beds,” which enabled me to define the limits of those 
great divisions of the Chalk-series which have been established 
by the paleontological studies of that formation during the last 
twenty years. 
The cores obtained from this well during the earlier stages of 
the work have neither the great diameter nor the length of those 
obtained when boring is carried on by the diamond rock-drill ; 
but I am convinced that for the purpose of the geologist the evi- 
dence supplied by the specimens obtained at Richmond was far 
more valuable than that which would be yielded by boring with a 
crown set with diamonds. In the latter case, as has been so well 
pointed out by Mr. H. J. Eunson, F.G.8.*, though very perfect 
cores are obtained from the hardest rocks, yet, in part through the 
grinding of one section of a core upon another, and in part through 
the action of the powerful current of water forced down the bore- 
hole, large portions of the softer deposits are washed away and 
lost. Mr. Eunson shows, in the case of a boring near Northamp- 
ton, executed with the diamond rock-drill, that where soft and hard 
rocks alternate, the cores brought to the surface represented in some 
eases only 64 per cent. of the depth bored. 
In the case of the Richmond boring, satisfactory cores of the 
harder beds were procured, and, what is of more importance, samples 
of all the beds passed through, soft and hard alike, were brought to 
the surface in the shell-pump. 
The specimens obtained were treated by various methods, according 
to their characters, in the geological laboratory of the Normal 
School of Science and Royal School of Mines. The harder rocks 
had thin slices cut from them for microscopic examination; the 
softer ones were broken up by water or by the action of frost, and 
all microscopic organisms in them carefully extracted by sifting and 
sorting. Wherever it was thought necessary, the specimens were 
submitted to partial chemical examination or to complete analysis. 
In giving the results of this series of studies, I shall confine 
myself to the statement of such observations as appear to throw 
new light upon important geological questions. 
Ill. Tae Tertiary StTrRata. 
The upper portion of the well was made some years ago; but a 
series of carefully selected specimens of the beds passed through has 
* «Minutes of Proc, Inst. Ciy. Eng.’ vol. lxxiv. pp. 274 and 281. 
