Forty-feet Reflecting Telescope. 335 
the ladders ; above this is another flat, with a termination 
of 16 inches at the top. 
The timber of the sides being tapering, a similar diminution 
of the flats and rounds has been attended to, especially as their 
size, in proportion to the sides, is far above what is generally 
used in building ladders. The flats and rounds are all made 
of solid English split oak. 
The lowest rounds are 2 inches thick in the middle, and if 
where they enter the sides. At the 21st round the thickness 
is if in the middle, and if at the shoulder. About the 31st 
round the thickness is if in the middle, and if at the shoulder, 
and this size is nearly preserved up to the end. Those parts 
of the rounds which enter the sides of the ladders have all been 
turned in a lathe, and are about f of an inch tapering, in order 
to fill the holes properly, which were also made a little tapering 
so as perfectly to answer the size of the rounds. 
The lowest flat, for a particular purpose in the erection of 
the ladders, which will be explained hereafter, is 4f inches by 
2. "The next, as far as the 10th, are 3f by if ; from the 11th 
to the 16th they are 2f by if; and from the 17th to the last 
2f by if inches. 
The two outside divisions of the ladders serve for mounting 
into the gallery, and therefore contain rounds as well as flats. 
The distance of the sides, the flat parts of which, as in com- 
mon ladders, are put facing each other, is 18 inches, and re- 
mains the same up to the end. But the two inside divisions, 
which have no rounds, are placed with the flat face outwards, 
and the distance between these faces being 2 feet 8 inches up 
to the top, the parallelism of these divisions is preserved out- 
side, while that of the mounting ladders is continued within. 
