1815.) An Essay on Rents. 45 
two rents) whose under side is on his right hand, meet with the up- 
per side, c J, of an unseparated rent, then that part of the separated 
rent, ed, which lies on the other side of the unseparated rent, is 
always a given distance, d, to his left hand. Let fig. 3. repre- 
sent the angular direction of such a junction as the man sees it 
when he looks towards the unseparated rent in the direction ab, 
fig. 2. Uc isthe upper side, and di the under side of the unsepa- 
rated rent. The dotted lines d A represent the angular figure of the 
separated rent on the under side, and the lines ) fg the same figure 
of this rent on the upper side of the separated rent. Suppose the 
line id represent a stratum on the under side of the unseparated 
rent, then the line 7 f will represent the same stratum on the up- 
per side of this rent. Again, let the line 4% represent the stratum 
in which the lowest extremity, i, of the separated rent on the under 
side of the unseparated rent is situated, then the line g will be the 
same stratum, and one that contains the lowest extremity of the 
former rent on the upper side of the latter rent. Nowa line, df, 
drawn from d, down the rent B B, at right angles to its horizontal 
direction c J, will pass through the point f, and a similarly disposed 
line, drawn from the point A, will pass through the point g; hence 
the part fg is equal to the part hd, and both make a similar angle 
with the perpendicular line g c; but the top of the part fg isa 
given distance below the top of the part hd; this distance 1s equak 
to that which the strata are lower on the upper than on the under 
side of the unseparated rent. Continue the rent g f upwards in its 
natural direction, till it reaches the line Jc, say at J: at that place 
it is the distance J d from the other part of the rent. This hori- 
zontal distance between the two parts of the separated rent, is 
caused entirely by the strata sinking lower on the upper than on the 
under side of the unseparated rent, and carrying down with them 
the separated rent on that side lower than the strata carry its oppo- 
site part on this side of the rent; for it is evident that, if the stra- 
tum g be elevated to hk, and the stratum Lf to di, the part of the 
separated rent, fg, will be directly opposite the part, hd, of the same 
‘rent. ' 
The unseparated rent in all junctions has hitherto, for the fol- 
lowing reasons, been considered the newer rent. The tabular 
masses in the unseparated rent preserve their usual arrangement 
opposite the ends of the separated rent, while these masses in the 
latter rent end against the side of the former rent; hence the se- 
parated rent must first have been formed and supplied with its con- 
tents, then another or unseparated rent produced across the rent, 
which, of course, would separate it, and which, in consequence of 
being formed the last, would not have its contents disturbed oppo- 
site that rent which it crossed. But such an arrangement of mat- 
ters in rents at these junctions does not, by any means, warrant 
this conclusion! For, if the separated rent be the older, the ta- 
bular masses in it must have been in such a state of solidity, that 
when the formation of the unseparated rent commenced, they could 
