Variation of the Altitude of the Mercurial Cylinder, which at 
moft is hardly three Inches, may be made as diitingiiiihabie , as 
if it were three Foot, or three Yards, or as much more , as is 
defired. 
The manner hereof is vifible enough by Figure I: where A 
B C reprefents the Tube, which may be either Blunt, or with 
a Head, as A B C ( by which latter lhape, more room is allow’d 
for any remainder of Air, to expand the better. ) This is to be 
filled with Quickfilver,and inverted as commonly; but into a 
VefFel of Stagnant Mercury, made after the fafhion of 1 K, that 
is, having its (ides about | or 4 inches high, and the Cavity of it 
equally big both above and below ; and if it can be ( befides 
that part, which is fill’d by the end of the Mercuriall Tube,that 
Hands in it ) of equal capacity with the hollow of the Cane about 
B : For then the Quickfilver rifing as much in the hollow of I, 
as it defeenefs at B 5 the difference of the height in the Receiver I, 
will be juft half the ufual difference. And if the receiving Vefftil 
IK have a bigger Cavity, the difference will be !efs,but if Jefs 3 'the 
difference will be greater : But, whether the difference be here- 
by made bigger or lefs, Tfs no great matter, fince by the con- 
trivance of the Wheel and Index ( which is more fully deferibed 
in the Preface to the Micrography ) the leaft variation may be 
made as fenfible as is defired, by diminiQiing the bignefs of the 
Cylinder F, and lengthening the Index E G, according to the 
Proportion requifite. 
An Account 
Of Four Suns, which very lately appear dinV ranee, and' 
of two Raine-bows, unufually pofited, feen in the fame 
Kingdom^ fomewhat longer ago.e . 
Thefe Phenomena are thought worthy to be inferted here, for 
the Speculation of the Curious in thofe Kingdoms 5 as they were 
pubiifht in the French Journal des $ caverns, of May 10.1666, v/d 
The 9 th of April oi this prefent year, about half an liotir paft 
rune, there appear’d three, Circles in die sky. One of them was 
very great, a little interrupted, and white every where,, without 
the: 
