$66 Dr. Herschei/s Description of a 
table was built for its support, which grew in size as the sheet 
advanced, till when finished, it was as large as the whole of it. 
In the formation of the sheet, cramping irons, seaming bars, 
setting tools, and claw-screws, such as are represented in the 
figures 22, 23, 24, 25, and 2 6, were made in great number, to 
confine and stretch the parts as they were seamed together. 
The small single sheets of which this large one is composed, 
are 3 feet 10 inches long, and about 23^- inches broad. Their 
thickness is less than the 36th part of an inch ; or, what will 
be a more precise measure, a square foot of it weighs about 
fourteen ounces. They are joined so, that the middle of a 
whole one always butts against the seam of the preceding two, 
in the manner of brick-work, where joints are crossed by 
bricks above and below. 
When the whole sheet was formed, which was done in a 
convenient barn not far from my house, the sides were cut 
perfectly parallel, and afterwards bent over at the ends in con- 
trary directions, as in fig. 21. to be ready to receive each 
other. A number of broad hooks, such as were proper for 
grasping the sides of the sheet, with loops at the other end for 
cords to go through, see fig. 22. were now prepared with their 
necessary tackle. 
Twelve pulleys were fastened about 11 feet high, on move- 
able beams, that might be drawn together ; six on each side. 
The sheet was now taken up, by occasioning all the corded 
hooks to be drawn at the same time, and while it was kept 
suspended our large table was taken to pieces. Another kind 
of support was now put under the middle of the sheet to re- 
ceive it. The form of this was that of an hollow segment, or 
quarter of a cylinder, cut lengthways, to the extent of a few 
