Notes and Comments. 
107 
"below, are noteworthy, and in this, as in the question of the 
■strength of the road, the importance of complete sub-crust 
drainage is to be emphasized. (5) Water among solids 
which it does not wet acts as an insulator, and in the making of 
tar, pitch, asphalt, or bitumen, macadam should be rigorously 
eliminated before stones and binder are brought together. 
The feasibility of chemical drying by adding to the partially- 
dried stones a suitable proportion of quicklime or unslaked 
cement is suggested. Summarily it is concluded that for each 
and every road aggregate there is a characteristic optimum 
proportion of water, which for efficient service of road user, 
the road-maker cannot afford to disregard. 
‘ CLEAT ’ IN COAL SEAMS. 
In the Geological Magazine for February, Professor Kendall 
has a valuable contribution on the question of the extraordin- 
ary persistence of the direction of the ‘ cleat ’ in coal seams, 
which direction seems to be entirely independent of the joints 
in the beds either above or below. It seems remarkable 
that the importance of this feature appears to have been so 
much neglected by geologists. Professor Kendall suggests 
the following working hypothesis with regard to it. ‘ When 
our Coal-measures were first laid down they would consist 
of a series of incoherent sands and muds, and this uncompacted 
condition may have persisted for a very long period, so long as 
pressures were not excessive and no cementation took place ; 
even surviving considerable tectonic disturbances, if we may 
judge by the condition of the Bovey Tracey Beds. The peats, 
however, would be subject to changes dependent upon pro- 
cesses entirely innate ; the gradual loss of volatile constituents 
or at least the resolution of the carbon compounds into new 
groupings and the conversion of the mother-substance of the 
coal into lignite. This has happened, as Principal Clayden 
informs me, to the logs and trunks in the Bovey Tracey 
deposits, and I have observed the same thing in the coaly 
lenticles at Alum Bay. Professor J. J. Stevenson, in the 
latest of his brilliant and closely reasoned memoirs on the 
formation of coal-beds, cites two instances of Quaternary 
peats passing into lignite. In this condition the coal sub- 
stance would be brittle and liable to joint. Now, let a de- 
forming stress or strain be applied, or perhaps a wave or 
tremor sweep the country, and the sheet of brittle material 
would be shattered, while the unconsolidated sands and 
■clays would, of course, be unaffected.’ 
ICE-FLOWS IN THE TRENT BASIN. 
In the same journal Mr. R. M. Deeley points out that 
with regard to the drift deposits of the Trent Basin, ‘ their 
1914 April 1. 
