Forty-feet Reflecting Telescope. 375 
about two-tenths of an inch, and being bent at rectangles, that 
part which is held down to the tube, and to the ten bars, 
keeps it steady, while that in the other direction serves as a 
ring, both to strengthen and confine the aperture. It pro- 
jects about three inches all around, and leaves an opening of 
4 feet 4 inches to the mouth of the telescope. 
The loop of suspension stands across the tube, and receives 
a round bar of iron, shaped as in fig. 35. which is left at li- 
berty to take its own position. To the places a b are hung 
two double pulleys, and at c, a single one; all turning upwards 
to meet the upper set of pulleys. 
"On the top of the stand, and round the centre beam, passes 
a ring of iron, 4 inches broad, and 1 inch thick, which con- 
tains a loop resembling that on the point of suspension at the 
telescope. This also receives a round iron bar, bent as in fig. 
3 6. and supports three double pulleys at d ef. 
Nothing can obstruct the motion of a tackle' more than the 
friction of the ropes against each other ; and as the utmost 
ease was required in the action of my pulleys, it was particu- 
larly necessary to guard against a defect of that kind. Ano- 
ther inconvenience was to be avoided, still more pernicious 
than the friction of the tackle. When pulleys are set, two, 
three, or four in a row, side by side, they will incline one way 
when the weight is drawn up, and another when it is let down. 
This may easily occasion an accident, which in the case of my 
large telescope must have been exceedingly troublesome, and 
probably in the end proved fatal ; for by the side inclination 
of the set, a rope will sometimes slip out of its place ; espe- 
cially as my ropes are well soaked in melted tallow to preserve 
them from moisture. This in summer will occasion dust to 
3C 2 
