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towards the Fire, I placed a triangular Piece of the 
fame Glafs with its Vertex towards the Fire nearly 
horizontal, but rather riling from the Fire} fo that 
its Bafe was a little higher than its Vertex > and upon 
it a Tube of Glafs, about 22 Inches long, and L of 
an Inch Diameter, near the Vertex and the Fire. 
This Tube receded from the Fire, moving about its 
Axis till it came to the Diflance of eight Inches } 
which is four Inches more than it receded the Day 
before upon the fame Piece of Coach-Glafs, before 
it was broke into this triangular Form. 
I was naturally led now to make ufe of two fup- 
porting Tubes, inftead of the triangular glafs Plane. 
Thefe were about eighteen Inches long each, and 1 ~ 
of an Inch in Diameter, and placed parallel to one 
another at the Didance of about two Inches, fo as 
to fupport the moving Tube near the Middle of ir. 
When very nearly horizontal by the Level, the fup- 
ported Tube moved from the Fire about its Axis to 
the Diflance of thirteen Inches : When the Supporters 
were a little raifed at their remote Ends, fo as mani* 
feftly by the Level to defeend towards the Fire, it 
receded to the Diftance of ten Inches, moving as be- 
fore about its Axis } but in this latter Cafe the Fire 
had declined a good deal j otherwife, probably, the 
Tube would have receded farther, tho' up-hill. 
The next Day, the fame Tube, when the fame 
fupporting Tubes were 8 “ Inches diftant from each 
other, receded nearly as before: When 12^ Inches 
from each other, it flood ftillj and when removed 
to the Diftance of i 6 ~- Inches, the fupported Tube 
very manifeftly changed its Motion, and went towards 
the 
