40 W. Pengelly on the Red Sandstones, 
A B C D be a series of parallel beds dipping towards B at the 
angle ABD, and forming a cliff section on a coast the trend 
of which coincides with the direction of the inclination of the beds, 
and which is represented by the plane of the paper. From A 
draw AD perpendicular to BD. It is obvious that the thick- 
ness of each bed is measured by that portion of the line A D 
which traverses it, and that therefore the total thickness of 
the section is the line A D, which, since A D B is a right- 
angled triangle, is equal to A B X sine z. B. Thus if A B is 
4 miles and the angle B contains 30^, then, since the sine of 30® 
= ^, the thickness of the beds = 4 miles X ^ = 2 miles. 
It was shown in my second paper* that from Goodrington 
Sands, Torbay, to the Straight Point, the mean dip of the forma- 
tion is 15® 30' towards N. 44® 30' E. (true), or in the direction of 
the latter from the former point ; and that, measured in a straight 
line the distance is fifteen miles ; so that, calculated in the manner 
just explained and with the assumptions previously mentioned, 
the thickness of this part of the formation would amount to fully 
four miles. 
The amounts and directions of the dips from the Straight 
Point to Charton Bay is shown in the following table : — 
LOCALITIES. 
DIPS. 
AMOUNTS. 
DIEECTIONS. 
Between Straight Point and Budleigh Salterton 
,, Budleigh Salterton and the Otter . . 
„ Weston Mouth and Beer Head 
9° 
5" 
7P 
79 
3° 
6° 
2© 
N. 66° E. (mag.) 
43° „ 
„ 37° „ „ 
M 180° „ 
„ 125° „ „ 
u 128° „ 
„ 120° „ „ 
5i° 
„ ioo« „ „ 
* «• Transactions," 1862-3, page 30. 
