[ 34i ] 
I. Two Letters from the Rev. Mr. Granville 
Wheler, F. R. S. to the Prefident, con- 
cerning a rotatory Motion of Glafs Tubes 
about their Axes, when placed in a certain 
' Manner before the Fire. 
I. 
SIR, London , Mar. zS. 17+50 
Read on March \ BOUT four Years ago, Mr. Charles 
\ 7 ff. Pf + Or me, of Ajbby de la Zouch in 
/ Jg^ Leicefterjhire, acquainted me, 
That, in drying his glafs Tubes for his diagonal Baro- 
meters (which for fome Years he has continued to 
make in much greater Perfection than any other Per- 
fon that I know of in England *)> he had obferved a 
rotatory Motion about their Axes , and at the fame 
time a progreilive one towards the Fire. He was fo 
obliging then as to promife at any time to fhew 
me the Experiment; but other Bulinefs intervening, 
I (till deferred accepting his Offier; having the lefs 
Curioiity to fee it, as I imagined the Motions were 
occafioned by the Draught of Air up the Chimney, 
aflifted by the Weight of the inclining Tube. But 
a little above a Year ago, making fome Stay at Ajhby, 
upon repeating his Olfer, I went to fee the 
Experiment, which anfwered fully to his De- 
feription: The Tubes, which were about four Feet 
long, and half an Inch over, moving at fix or 
eight Inches Diftance from the Fire, not only pro- 
greflively, and about their Axes along the Side- 
Wall they lean’d again!!, but along the Front -Wall 
X x of 
One of which Mr. Wheler mad.: a Prefent of to ih: Royal See 
