44 An Essay on Rents. ; [JuLy, 
are joined to those of another, BB, in a direction cd, which is ho- 
rizontal, they are joined together in their horizontal directions, 
Ifa miner, in travelling downwards in the angular direction, al, 
of a rent, B, meet with another rent, A, having a reverse position, 
and whose upper side, fg, is horizontally joined to both sides of 
that part of the rent in which he is standing, then the part of the 
latter rent which is joined to the wnder side of the former rent, will 
join it, as at c, above the place where the part a J joins it on the 
opposite side. 
Let it be remembered that the strata are always lower on the up- 
per side than on the under side of every rent of this shape, then this 
separation of the rent B into parts will be easily accounted for. 
The lowest extremities of any one rent are generally situated in one 
stratum ; hence, as the matter of the formation contracted, these 
extremities of both parts of the separated rent would necessarily 
sink with the stratum that contains them; but this stratum, as well 
as those above it, sunk a greater distance on the upper side, than on 
the under side of the unseparated rent, and brought down the part 
of the separated rent which lies on the former side as much lower 
than that part of this rent on the latter side of the uwaseparated rent, 
as the strata are lower on this than on that side of the last rent. 
This ‘‘ want of apposition,” therefore, in the two parts of one 
of the joining rents which lie on opposite sides of the other is the 
effect of that unequal contraction of the matter which produced 
the rents, and is not caused by the action of a newer rent on an 
older, as has been generally supposed. 
In every junction where the unseparated rent is the larger, it is as 
old as, if not older than, the separated rent; but when it is the 
smaller, it is always the newer of the two joining rents. 1 would 
in both instances, however, be understood to mean, that the for- 
mation of these rents took place during the process of the matter’s 
consolidation ; and when J say one is older than the other rent, I 
only mean that the commencement of the formation of the older 
happened before that of the newer rent; and, not that any one rent 
was completely formed and filled before the formation of any other 
had commenced. 
2. Of angular Junetions. 
When two rents are joined together in their angular directions, 
they exhibit the appearance of fig. 3, Plate XXXV.; in which the 
parts, bg, hd, of one rent, A, are joined to another rent, BB, in 
a direction, 6 fg, which is parallel, or nearly so, to the angular 
direction of both rents. I will at present only describe the hori- 
zontal junctions of two rents that meet each other at nearly right 
angles; one of which, the unseparated rent, contains both kinds of 
the earthy tabular masses, and the other, or the separated rent, con- 
tains both of the earthy associated with the metallic tabular masses. 
If a miner, in travelling in the horizontal direction of a rent, a b, 
fig. 2, (which figure is a horizontal view of an angular junction of 
