TRANSACTIONS. 87 
The underlying strata over a wide area round Dumfries is 
Permian Breccia, covered over with boulder clay of a somewhat 
friable nature. The Breccia stands out at Cluden Mills, the Craigs, 
and other places. All are familiar with the Permian sandstone of 
Locharbriggs and other quarries in the county, but from the soft 
character of the stone, it does not retain marks of glaciation at 
exposed places so well as harder rocks. 
A striking feature of the locality, as of nearly the whole of 
the Scottish Lowlands, is the rolling character of the country ; the 
green knolls, and rampart-looking ridges usually called “ kames,” 
composed of stones of all sizes, gravel, and sand. It is admitted 
that these mounds cannot be clearly accounted for, but Professor 
James Geikie is of opinion that they point to abundant streams of 
running water discharged across the country from the rapid melt- 
ing of snow and ice, to a “ pluvial period,” or after the Ice Age 
“Great Thaw” spoken of by Sir Charles Lyall. 
N.B.—It may be noticed here, that Dr Croll and others, who 
have made calculations for the eccentricities of the orbit of the 
earth and other planets, used Leverrier’s Formula in making their 
calculations. In conversation with Dr Young, Professor of Geology 
in the University of Glasgow, he hinted to me that the formula 
was not reliable. If this were true, it is obvious that the conclu- 
sions as to the last period of high eccentricity might be erroneous. 
In these circumstances I thought it would be well to make enquiry 
at the highest authority whether the formula was reliable or not. 
Dr Chinnock very kindly, in the interests of the Society, and on 
my own account, wrote to the Astronomer Royal making the 
enquiry. The courteous reply received from Greenwich Observa- 
tory is herewith given in full. It will be seen that Leverrier’s 
Formula cannot be considered unreliable for the Zas¢ Glacial Epoch, 
which is all that we have under consideration. When every 
allowance is made it does not appear that the period covered by 
the epoch, as calculated by Dr Croll and others, can be very far 
out. 
J. W. 
Rovyat OBSERVATORY, GREENWICH, 
Lonvon, 8.E., 1890, Sept. 19. 
Dr E. J. Curynocg, 
Drax Sir, 
Leverrier’s Formula for the eccentricities 
of the orbit of the earth and other planets have been computed with 
great care, but the calculations are rather complicated, and independ- 
