Forty-feet R fleeting Telescope. 3 6g 
broad. They were shaped red hot upon a concave tool, which 
had the required curvature and angle of the slips. The pieces 
were long enough to form a complete quadrant of the circle, 
with the ends sufficiently projecting to be seamed together. 
Before they were joined the sides received another bending, 
as in fig. 30. which was given them by tools of a proper con- 
vexity. A back was next prepared, consisting of a slip of iron 
turned up at both sides, and also bent to the circle, as in fig. 
31. Last of all, the four quadrants having been put together, 
and a back put round them, the whole was firmly seamed to- 
gether, so as to resemble a hollow triangular bar made into a 
hoop or ring, of a proper diameter to go closely into the tube, 
so as to keep it extended, and braced to the cylindrical form. 
A section of the ring with the bottom seam not quite pressed 
down, in order to shew, it better, is represented in fig. 32. 
One of these rings was put into the middle of every one of 
the small sheets, which brought them to about 23 inches from 
each other. They were carried in edgeways, and afterwards 
turned about and forced into their respective places. In order 
to get them in, as they were all obliged to go in from one side, 
there was substituted, in the room of the circular arches, a 
kind of temporary props, like fig. 33. that could be easily re- 
moved, one at a time, and were narrow enough at a b to pass 
through the hoops while they advanced ; and as soon as a ring 
was in its proper place, no further support became necessary. 
In this manner we secured the cylindrical form of the tube ; 
and as soon as this was accomplished, we had every thing re- 
moved from within and without, and began to give the tube 
three or four good coats of paint, inside as well as outside ; in 
