3^0 Dr. Herschei/s Description of a 
flat, or half way up. The upper end is secured with an iron, 
as in fig. 10. through the loop of which passes a strap-bolt 
that holds it at the same time with the triangular brace, which 
will be described, to the ladders. The lower end is strap-bolted 
down upon the beams, as in fig. 11. 
The two long side- bracing poles are supported each by two 
less poles, which meet them at one half and one quarter of 
their length from the bottom ; or at a height opposite to the 
5th and 10th flats of the ladders. Those poles which meet 
the great ones in the middle are placed with their lower ends 
upon the middle beam at 19 and 20 ; and the shortest rest at 
21 and 22. They add very materially to the steadiness of 
the frame in the east and west, or lateral direction ; at the 
bottom they are also fastened by strap-bolts as in fig. 11. and 
at the top by loops, as in fig. 10. They may also be seen in 
%. 1. 
The next braces we are to describe are those of the sides of 
the ladders, and these it will be seen by fig. 13. are of so simple 
a nature, that a bare inspection of their representation will be 
sufficient. The size of the horizontal pieces is 6 inches by 3-t; 
but those which are parallel to the ladders, and are of no other 
use than to keep the rest in their places, or as it were brace- 
bracers, are only 3^ by 2-^. 
Besides these there are three sets of braces, which serve to 
confine the poles to their stations. The highest set meets 
the side brace of fig. 13. at the 13th flat. The next meets 
the middle brace at the 10th flat, and both these make with 
the here mentioned side braces a triangle, in the vertex of 
which is inclosed the large pole that is braced by them. At 
the 3th flat a third- set of braces, which incloses the two small 
