Tube, having fixed in the common Focus of the two 
Glades, four threads eroding one another in the Center* 
under Angles of 45 Degrees. This Tube he firmly fix’d 
to the Plain of a Mural Arch, which had been for above 
30 Years immoveably cemented to the Wall of the 
Royal Obfervatory , to which he chofe to ' -fix it, becaufe 
of the great Solidity thereof, and its being therefore 
the lefs liable to lhake ; and that after having flood 
30 Years, there was no fear of its fettling any further in 
the fpace of one Year ; befides, that it was eafy to per- 
ceive if any fuch alteration fhould happen to ir. 
Having therefore fix’d his three Foot Tube as above, 
fo that, about the beginning of April, 17 14* New Stile , 
( I luppofe, becaufe then Sirius was in Square to the 
Sun') the Star being exadtly in the Meridian , pad over 
the Center of the Tube, he obferved that ^n the 20th 
of April the Star touched the Horizontal Thread with 
its under edge, being apparently all above it, in the 
inverting Tube, but really below. On the 15th of May, 
and 6th of June , it pad again by the Center. On June 
the 27th it appeared a little under, and on Jul) the 9th 
it was found to touch the under part of the Thread. On 
Ottober the 5th it again pad by the Center; but on De- 
cember the 19th, it touched the upper part of the Thread* 
January the x 8th, 1715. being the colded Day of that 
Winter, it pad exadly by the Center; and on the 27th 
of March , and the 1 ft of April, it almod touched the 
upper fide of the Horizontal Thread, from which it 
feem’d a little feparated. But on June the 7 th, it pad 
a little under the Center ; and on June the 29th, the 
Sun being then in conjunction with Sirius , it pad under 
the Thread, fo as to touch it with its upper edge. 
Whence it appears, that in the fpace of the whole Year, 
there had been no other variation of the Meridian Alti- 
tude of Sirius, than the breadth of the Thread, which 
appear’d 
